William N. Levine, MD

ABSTRACT

There is a paucity of evidence describing the types and rates of postoperative complications following total shoulder arthroplasty (TSA). We sought to analyze the complications following TSA and determine their effects on described outcome measures.

Using discharge data from the weighted Nationwide Inpatient Sample from 2006 to 2010, patients who underwent primary TSA were identified. The prevalence of specific complications was identified using the International Classification of Diseases, 9th Revision, Clinical Modification (ICD-9-CM) codes. The data from this database represent events occurring during admission, prior to discharge. The associations between patient characteristics, complications, and outcomes of TSA were evaluated. The specific outcomes analyzed in this study were mortality and length of stay (LOS).

A total of 125,766 patients were identified. The rate of complication after TSA was 6.7% (8457 patients). The most frequent complications were respiratory, renal, and cardiac, occurring in 2.9%, 0.8%, and 0.8% of cases, respectively. Increasing age and total number of preoperative comorbidities significantly increased the likelihood of having a complication. The prevalence of postoperative shock and central nervous system, cardiac, vascular, and respiratory complications was significantly higher in patients who suffered postoperative mortality (88 patients; 0.07% mortality rate) than in those who survived surgery (P < 0.0001). In terms of LOS, shock and infectious and vascular complications most significantly increased the length of hospitalization.

Postoperative complications following TSA are not uncommon and occur in >6% of patients. Older patients and certain comorbidities are associated with complications after surgery. These complications are associated with postoperative mortality and increased LOS.

Continue to: Total shoulder arthroplasty...

Total shoulder arthroplasty (TSA) provides a predictably high level of satisfaction with survival as high as 92% at 15 years.¹ As implant instrumentation and surgical technique and understanding have improved, the frequency of TSAs being performed has also increased.² Although there are enough data on long-term surgical complications following TSA,^1,3-6 there is a paucity of evidence delineating the incidence and types of postoperative complications during hospitalization. Several current issues motivate the improved understanding of TSA, including the increasing number of TSAs being performed, the desire to improve quality of care, and the desire to create financially efficient healthcare.

The purpose of this study is to detail the postoperative complications that occur following TSA using a large national database. Specifically, our goals are to determine the incidence and types of complications after shoulder arthroplasty, determine the patient factors that are associated with these complications, and evaluate the effects of these complications on postoperative in-hospital mortality and length of stay (LOS). Our hypothesis is that there would be a correlation between specific patient factors and complications and that these complications would adversely correlate to patient postoperative outcomes.

METHODS

DESIGN

We conducted a retrospective analysis of TSAs captured by the Nationwide Inpatient Sample (NIS) database between 2006 and 2010. The NIS is the largest all-payer inpatient database that is currently available to the public in the United States.⁷

The NIS is a part of the Healthcare Cost and Utilization Project funded by the Agency for Healthcare Research and Quality (AHRQ) and the US Department of Health and Human Services. The NIS database is designed to approximate a 20% sample of US hospitals and the patients they serve, including community, academic, general, and specialty-specific hospitals such as orthopedic hospitals.⁷ The 2010 update of the NIS database contains discharge data from 1051 hospitals across 45 states, with a representative sample of >39 million inpatient hospital stays.⁷ The NIS database and its data sources have been independently validated and assessed for quality each year since 1988.⁸Furthermore, comparative analysis of multiple database elements and distributions has been validated against standard norms, including the National Hospital Discharge Survey.⁹ The NIS database has been used in numerous published studies.^2,10,11

PATIENT SELECTION

The yearly NIS databases from 2006 to 2010 were compiled. Patients aged ≥40 years who underwent a TSA were identified using the International Classification of Diseases, 9th Revision (ICD-9), procedural code 81.80. Exclusion criteria were patients with a primary or a secondary diagnosis of humeral or scapular fracture, chronic osteomyelitis, rheumatologic diseases, or evidence of concurrent malignancy (Figure 1).

Native to NIS are patient demographics, including age, sex, and race. Patient comorbidities as described by Elixhauser and colleagues¹² are also included in the database.

Continue to: OUTCOMES...

 

 

OUTCOMES

The primary outcome of this study was a description of the type and frequency of postoperative complications of TSA. To conduct this analysis, we queried the TSA cohort for specific ICD-9 codes representing acute cardiac, central nervous system, infectious, gastrointestinal, genitourinary, postoperative shock, renal, respiratory, surgical, vascular, and wound complications. The ICD-9 codes used to identify complications were modeled according to previous literature on various surgical applications and were further parsed to reflect only acute postoperative diagnoses^13-15(see the Appendix for the comprehensive list of ICD-9 codes).

Two additional outcomes were analyzed, including postoperative mortality and LOS. Postoperative mortality was defined as death occurring prior to discharge. We calculated the average LOS among the complication and the noncomplication cohort.

STATISTICAL ANALYSIS

Patient demographics and target outcomes of the study were analyzed by frequency distribution. Where applicable, the chi-square and the Student’s t tests were used to confirm the statistical difference for dichotomous and continuous variables, respectively. Multivariate regressions were performed after controlling for possible clustering of the data using a generalized estimating equation following a previous analytical methodology.^16-20 The results are reported with odds ratios and 95% confidence intervals where applicable, all statistical tests with P ≤ 0.05 were considered to be significant, and all statistical tests were two-sided. We conducted all analyses using SAS, version 9.2 (SAS Institute).

RESULTS

From 2006 to 2010, a weighted sample of 141,973 patients was found to undergo a TSA. After applying our inclusion and exclusion criteria, our study cohort consisted of 125,766 patients (Figure 1).

Continue to: OVERALL TSA COHORT DEMOGRAPHICS...

 

 

OVERALL TSA COHORT DEMOGRAPHICS

The average age of the TSA cohort was 69.4 years (standard deviation [SD], 21.20), and 54.1% were females. The cohort had significant comorbidities, with 83.3% of them having at least 1 comorbidity at the time of surgery. Specifically, 31.3% of the patients had 1 comorbidity, 26.5% had 2 comorbidities, and 25.4% had ≥3 comorbidities. Hypertension was the most common comorbidity present in 66.2% of patients, and diabetes was the second most common comorbidity with a prevalence of 16.8%.

COMPLICATION COHORT DEMOGRAPHICS

An overall postoperative complication rate of 6.7% (weighted sample of 8457 patients) was noted in the overall TSA cohort. The TSA cohort was dichotomized into patients who suffered at least 1 complication (weighted, n = 8457) and patients undergoing routine TSAs (weighted, n = 117,308). The average age was significantly higher in the complication vs routine cohort (71.38 vs 69.27 years, P < 0.0001). Similarly, there were significantly more comorbidities (2.51 vs 1.71, P < 0.0001) in the complication cohort.

COMPLICATIONS

We noted a complication rate of 6.7% (weighted sample of 8457 patients). A single complication was noted in 5% of these patients, whereas 1.3% and 0.4% of the patients had 2 and ≥3 complications, respectively. Respiratory abnormalities (2.9%), acute renal failure (0.8%), and cardiac complications (0.8%) were the most prevalent complications after TSA. The list of complications is detailed in Figure 2. Logistic regression analysis of patient characteristics predicting complications showed that advanced age (odds ratio [OR], 2.1 in those aged ≥85 years) and increasing number of comorbidities (≥3; OR, 3.5) were most significant in predicting complications (all P < 0.0001) (Figure 3). Despite the ubiquity of hypertension in this patient population, it was not a significant predictor of complication (OR, 0.9); in contrast, pulmonary disorders (OR, 5.1) and fluid and electrolyte disorders (4.0) were most strongly associated with the development of a postoperative complication after surgery (Figure 4).

EFFECT OF COMPLICATIONS ON LOS

The average length of hospitalization was 2.3 days (95% confidence interval, 2.22-2.25) among the entire cohort. The average LOS was longer in the complication cohort (3.9 days) than in patients who did not have a complication (2.1 days, P < 0.0001). Of the specific complications noted, hemodynamic shock (11.8 days); infectious, most commonly pneumonia (7.6 days); and vascular complications (6.9 days) were associated with the longest hospitalizations. This result is summarized in Figure 5.

MORTALITY

An overall postoperative (in-house) mortality rate of 0.07% was noted (weighted, n = 88). Comparison between the patient cohort that died vs those who survived TSA resulted in significant differences in the rates of complications. Complications that were most significantly different between the cohorts included cardiac (60.47% vs 0.75%, P < 0.0001), postoperative shock (26.61% vs 0.04%, P < 0.0001), and respiratory complications (43.1% vs 2.8%, P < 0.0001). It is important to note that the overall rate of postoperative shock was exceedingly low in the TSA cohort, but it was highly prevalent in the mortality cohort, occurring in 26.61% of patients. A summary of the mortality statistics is presented in Figure 6.

Continue to: DISCUSSION...

 

 

DISCUSSION

TSA continues to be associated with high levels of satisfaction;¹ as a result, its incidence is increasing.² As our understanding and efficiency improves nationally, it is imperative that we determine the short-term and longer-term outcomes and complications. In addition, the factors that may affect prognosis must be elucidated to provide a more individualized and effective standard of care. To date, most of the outcome studies of TSA have evaluated long-term outcomes and specific implant-related complications.^1,5,6,21,22 Our intent was to evaluate the complications that occur in the postoperative period and their effect on unique “patient care” outcomes. With knowledge of these complications and the predisposing factors, we can better assess patients, risk-stratify, and provide appropriate guidelines.

We noted that complications occurring after TSA are not uncommon, with >6% of patients suffering a postoperative complication. In this study, the number of complications noted was associated with worse patient outcomes. In addition, we noted that patients undergoing a TSA have a significant burden of comorbidities; however, hematologic and fluid disorders (eg, iron deficiency anemia, pulmonary circulatory disorders, and fluid imbalances) were most important in predicting postoperative complications.

Increased LOS in the hospital after TSA was associated with the occurrence of complications. Of all noted complications, shock and infectious and vascular complications led to the longest hospitalizations. Hospital-acquired pneumonia was the most common infectious etiology, while pulmonary embolism and deep vein thrombosis were the most consistent vascular complications. Although seldom studied in the TSA population, a similar finding has been noted in patients after THA. O’Malley and colleagues,²³ using the American College of Surgeon’s National Surgical Quality Improvement Program database, identified independent factors that were associated with complications and average prolonged LOS. They noted that the occurrence of major complications was associated with a prolonged LOS. Some, but not all the major complications, included organ space infection, cardiac events, pneumonia, and venous thromboembolic events.²³ Therefore, attempts to limit the amount of time spent in hospitals and control the associated costs must focus on managing the incidence of complications.

Postoperative mortality after TSA was uncommon, occurring in 0.07% of the patients in this study. The low incidence of mortality noted in this study is probably related to the fact that our data represent mortality, whereas in the hospital and, unlike most mortality studies, it does not account for patient demise that may occur in the months after surgery. Other reports have noted that mortality occurs in <1.5% of these patients.^24-28 Singh and colleagues²⁵ observed in their evaluation of perioperative mortality after TSA a mortality rate of 0.8% with 90 days after 4380 shoulder replacements performed at their institution. Using multivariate analysis, they were able to identify associations between mortality and increasing American Society of Anesthesiology (ASA) class and Charlson Comorbidity Index. These results in relation to ours would indicate that the majority of patients who die after shoulder arthroplasty do so after initial discharge. Although we could not determine a causal relationship between mortality and patient comorbidities, we noted that certain complications strongly correlated with mortality. In patients who died, there was a relatively high incidence of cardiac (60.5%) and respiratory (43.1%) complications. Similarly, although postoperative shock was almost nonexistent in the patients who survived surgery (0.04%), it was much more common in the patients who suffered mortality (26.6%).

This study is not without limitations. Data were extracted from a national database, therefore precluding the inclusion of specific details of surgery and functional assessment. Inherent to ICD-9 coding, we were unable to assess the exact detail and severity of complications. For instance, we cannot be certain what criteria were used to define “acute renal failure” for each patient. This study is retrospective in nature and therefore adequate randomization and standardization of patients is not possible. Similarly, the nature of the database may not allow for exacting our inclusion and exclusion criteria. However, the large sample size of the patient population lessens the chance of potential biases and type 2 errors. Prior to October 2010, reverse shoulder arthroplasty was coded under the ICD-9procedural code 81.80 as TSA. Therefore, there is some overlap between TSA and reverse shoulder arthroplasty in our data. Reverse shoulder arthroplasty is now coded under ICD-9 procedural code 81.88. It is possible that results may differ if reverse shoulder arthroplasty were excluded from our patient cohort. This can be an area of future research.

CONCLUSION

Although much is known about the long-term hardware and functional complications after TSA, in this study, we have attempted to broaden the understanding of perioperative complications and the associated sequelae. Complications are common after TSA surgery and are related to adverse outcomes. In the setting of healthcare changes, the surgeon and the patient must understand the cause, types, incidence, and outcomes of medical and surgical complications after surgery. This allows for more accurate “standard of care” metrics. Further large-volume multicenter studies are needed to gain further insight into the short- and long-term outcomes of TSA.

ABSTRACT

There is a paucity of evidence describing the types and rates of postoperative complications following total shoulder arthroplasty (TSA). We sought to analyze the complications following TSA and determine their effects on described outcome measures.

Using discharge data from the weighted Nationwide Inpatient Sample from 2006 to 2010, patients who underwent primary TSA were identified. The prevalence of specific complications was identified using the International Classification of Diseases, 9th Revision, Clinical Modification (ICD-9-CM) codes. The data from this database represent events occurring during admission, prior to discharge. The associations between patient characteristics, complications, and outcomes of TSA were evaluated. The specific outcomes analyzed in this study were mortality and length of stay (LOS).

A total of 125,766 patients were identified. The rate of complication after TSA was 6.7% (8457 patients). The most frequent complications were respiratory, renal, and cardiac, occurring in 2.9%, 0.8%, and 0.8% of cases, respectively. Increasing age and total number of preoperative comorbidities significantly increased the likelihood of having a complication. The prevalence of postoperative shock and central nervous system, cardiac, vascular, and respiratory complications was significantly higher in patients who suffered postoperative mortality (88 patients; 0.07% mortality rate) than in those who survived surgery (P < 0.0001). In terms of LOS, shock and infectious and vascular complications most significantly increased the length of hospitalization.

Postoperative complications following TSA are not uncommon and occur in >6% of patients. Older patients and certain comorbidities are associated with complications after surgery. These complications are associated with postoperative mortality and increased LOS.

Continue to: Total shoulder arthroplasty...

Total shoulder arthroplasty (TSA) provides a predictably high level of satisfaction with survival as high as 92% at 15 years.¹ As implant instrumentation and surgical technique and understanding have improved, the frequency of TSAs being performed has also increased.² Although there are enough data on long-term surgical complications following TSA,^1,3-6 there is a paucity of evidence delineating the incidence and types of postoperative complications during hospitalization. Several current issues motivate the improved understanding of TSA, including the increasing number of TSAs being performed, the desire to improve quality of care, and the desire to create financially efficient healthcare.

The purpose of this study is to detail the postoperative complications that occur following TSA using a large national database. Specifically, our goals are to determine the incidence and types of complications after shoulder arthroplasty, determine the patient factors that are associated with these complications, and evaluate the effects of these complications on postoperative in-hospital mortality and length of stay (LOS). Our hypothesis is that there would be a correlation between specific patient factors and complications and that these complications would adversely correlate to patient postoperative outcomes.

METHODS

DESIGN

We conducted a retrospective analysis of TSAs captured by the Nationwide Inpatient Sample (NIS) database between 2006 and 2010. The NIS is the largest all-payer inpatient database that is currently available to the public in the United States.⁷

The NIS is a part of the Healthcare Cost and Utilization Project funded by the Agency for Healthcare Research and Quality (AHRQ) and the US Department of Health and Human Services. The NIS database is designed to approximate a 20% sample of US hospitals and the patients they serve, including community, academic, general, and specialty-specific hospitals such as orthopedic hospitals.⁷ The 2010 update of the NIS database contains discharge data from 1051 hospitals across 45 states, with a representative sample of >39 million inpatient hospital stays.⁷ The NIS database and its data sources have been independently validated and assessed for quality each year since 1988.⁸Furthermore, comparative analysis of multiple database elements and distributions has been validated against standard norms, including the National Hospital Discharge Survey.⁹ The NIS database has been used in numerous published studies.^2,10,11

PATIENT SELECTION

The yearly NIS databases from 2006 to 2010 were compiled. Patients aged ≥40 years who underwent a TSA were identified using the International Classification of Diseases, 9th Revision (ICD-9), procedural code 81.80. Exclusion criteria were patients with a primary or a secondary diagnosis of humeral or scapular fracture, chronic osteomyelitis, rheumatologic diseases, or evidence of concurrent malignancy (Figure 1).

Native to NIS are patient demographics, including age, sex, and race. Patient comorbidities as described by Elixhauser and colleagues¹² are also included in the database.

Continue to: OUTCOMES...

 

 

OUTCOMES

The primary outcome of this study was a description of the type and frequency of postoperative complications of TSA. To conduct this analysis, we queried the TSA cohort for specific ICD-9 codes representing acute cardiac, central nervous system, infectious, gastrointestinal, genitourinary, postoperative shock, renal, respiratory, surgical, vascular, and wound complications. The ICD-9 codes used to identify complications were modeled according to previous literature on various surgical applications and were further parsed to reflect only acute postoperative diagnoses^13-15(see the Appendix for the comprehensive list of ICD-9 codes).

Two additional outcomes were analyzed, including postoperative mortality and LOS. Postoperative mortality was defined as death occurring prior to discharge. We calculated the average LOS among the complication and the noncomplication cohort.

STATISTICAL ANALYSIS

Patient demographics and target outcomes of the study were analyzed by frequency distribution. Where applicable, the chi-square and the Student’s t tests were used to confirm the statistical difference for dichotomous and continuous variables, respectively. Multivariate regressions were performed after controlling for possible clustering of the data using a generalized estimating equation following a previous analytical methodology.^16-20 The results are reported with odds ratios and 95% confidence intervals where applicable, all statistical tests with P ≤ 0.05 were considered to be significant, and all statistical tests were two-sided. We conducted all analyses using SAS, version 9.2 (SAS Institute).

RESULTS

From 2006 to 2010, a weighted sample of 141,973 patients was found to undergo a TSA. After applying our inclusion and exclusion criteria, our study cohort consisted of 125,766 patients (Figure 1).

Continue to: OVERALL TSA COHORT DEMOGRAPHICS...

 

 

OVERALL TSA COHORT DEMOGRAPHICS

The average age of the TSA cohort was 69.4 years (standard deviation [SD], 21.20), and 54.1% were females. The cohort had significant comorbidities, with 83.3% of them having at least 1 comorbidity at the time of surgery. Specifically, 31.3% of the patients had 1 comorbidity, 26.5% had 2 comorbidities, and 25.4% had ≥3 comorbidities. Hypertension was the most common comorbidity present in 66.2% of patients, and diabetes was the second most common comorbidity with a prevalence of 16.8%.

COMPLICATION COHORT DEMOGRAPHICS

An overall postoperative complication rate of 6.7% (weighted sample of 8457 patients) was noted in the overall TSA cohort. The TSA cohort was dichotomized into patients who suffered at least 1 complication (weighted, n = 8457) and patients undergoing routine TSAs (weighted, n = 117,308). The average age was significantly higher in the complication vs routine cohort (71.38 vs 69.27 years, P < 0.0001). Similarly, there were significantly more comorbidities (2.51 vs 1.71, P < 0.0001) in the complication cohort.

COMPLICATIONS

We noted a complication rate of 6.7% (weighted sample of 8457 patients). A single complication was noted in 5% of these patients, whereas 1.3% and 0.4% of the patients had 2 and ≥3 complications, respectively. Respiratory abnormalities (2.9%), acute renal failure (0.8%), and cardiac complications (0.8%) were the most prevalent complications after TSA. The list of complications is detailed in Figure 2. Logistic regression analysis of patient characteristics predicting complications showed that advanced age (odds ratio [OR], 2.1 in those aged ≥85 years) and increasing number of comorbidities (≥3; OR, 3.5) were most significant in predicting complications (all P < 0.0001) (Figure 3). Despite the ubiquity of hypertension in this patient population, it was not a significant predictor of complication (OR, 0.9); in contrast, pulmonary disorders (OR, 5.1) and fluid and electrolyte disorders (4.0) were most strongly associated with the development of a postoperative complication after surgery (Figure 4).

EFFECT OF COMPLICATIONS ON LOS

The average length of hospitalization was 2.3 days (95% confidence interval, 2.22-2.25) among the entire cohort. The average LOS was longer in the complication cohort (3.9 days) than in patients who did not have a complication (2.1 days, P < 0.0001). Of the specific complications noted, hemodynamic shock (11.8 days); infectious, most commonly pneumonia (7.6 days); and vascular complications (6.9 days) were associated with the longest hospitalizations. This result is summarized in Figure 5.

MORTALITY

An overall postoperative (in-house) mortality rate of 0.07% was noted (weighted, n = 88). Comparison between the patient cohort that died vs those who survived TSA resulted in significant differences in the rates of complications. Complications that were most significantly different between the cohorts included cardiac (60.47% vs 0.75%, P < 0.0001), postoperative shock (26.61% vs 0.04%, P < 0.0001), and respiratory complications (43.1% vs 2.8%, P < 0.0001). It is important to note that the overall rate of postoperative shock was exceedingly low in the TSA cohort, but it was highly prevalent in the mortality cohort, occurring in 26.61% of patients. A summary of the mortality statistics is presented in Figure 6.

Continue to: DISCUSSION...

 

 

DISCUSSION

TSA continues to be associated with high levels of satisfaction;¹ as a result, its incidence is increasing.² As our understanding and efficiency improves nationally, it is imperative that we determine the short-term and longer-term outcomes and complications. In addition, the factors that may affect prognosis must be elucidated to provide a more individualized and effective standard of care. To date, most of the outcome studies of TSA have evaluated long-term outcomes and specific implant-related complications.^1,5,6,21,22 Our intent was to evaluate the complications that occur in the postoperative period and their effect on unique “patient care” outcomes. With knowledge of these complications and the predisposing factors, we can better assess patients, risk-stratify, and provide appropriate guidelines.

We noted that complications occurring after TSA are not uncommon, with >6% of patients suffering a postoperative complication. In this study, the number of complications noted was associated with worse patient outcomes. In addition, we noted that patients undergoing a TSA have a significant burden of comorbidities; however, hematologic and fluid disorders (eg, iron deficiency anemia, pulmonary circulatory disorders, and fluid imbalances) were most important in predicting postoperative complications.

Increased LOS in the hospital after TSA was associated with the occurrence of complications. Of all noted complications, shock and infectious and vascular complications led to the longest hospitalizations. Hospital-acquired pneumonia was the most common infectious etiology, while pulmonary embolism and deep vein thrombosis were the most consistent vascular complications. Although seldom studied in the TSA population, a similar finding has been noted in patients after THA. O’Malley and colleagues,²³ using the American College of Surgeon’s National Surgical Quality Improvement Program database, identified independent factors that were associated with complications and average prolonged LOS. They noted that the occurrence of major complications was associated with a prolonged LOS. Some, but not all the major complications, included organ space infection, cardiac events, pneumonia, and venous thromboembolic events.²³ Therefore, attempts to limit the amount of time spent in hospitals and control the associated costs must focus on managing the incidence of complications.

Postoperative mortality after TSA was uncommon, occurring in 0.07% of the patients in this study. The low incidence of mortality noted in this study is probably related to the fact that our data represent mortality, whereas in the hospital and, unlike most mortality studies, it does not account for patient demise that may occur in the months after surgery. Other reports have noted that mortality occurs in <1.5% of these patients.^24-28 Singh and colleagues²⁵ observed in their evaluation of perioperative mortality after TSA a mortality rate of 0.8% with 90 days after 4380 shoulder replacements performed at their institution. Using multivariate analysis, they were able to identify associations between mortality and increasing American Society of Anesthesiology (ASA) class and Charlson Comorbidity Index. These results in relation to ours would indicate that the majority of patients who die after shoulder arthroplasty do so after initial discharge. Although we could not determine a causal relationship between mortality and patient comorbidities, we noted that certain complications strongly correlated with mortality. In patients who died, there was a relatively high incidence of cardiac (60.5%) and respiratory (43.1%) complications. Similarly, although postoperative shock was almost nonexistent in the patients who survived surgery (0.04%), it was much more common in the patients who suffered mortality (26.6%).

This study is not without limitations. Data were extracted from a national database, therefore precluding the inclusion of specific details of surgery and functional assessment. Inherent to ICD-9 coding, we were unable to assess the exact detail and severity of complications. For instance, we cannot be certain what criteria were used to define “acute renal failure” for each patient. This study is retrospective in nature and therefore adequate randomization and standardization of patients is not possible. Similarly, the nature of the database may not allow for exacting our inclusion and exclusion criteria. However, the large sample size of the patient population lessens the chance of potential biases and type 2 errors. Prior to October 2010, reverse shoulder arthroplasty was coded under the ICD-9procedural code 81.80 as TSA. Therefore, there is some overlap between TSA and reverse shoulder arthroplasty in our data. Reverse shoulder arthroplasty is now coded under ICD-9 procedural code 81.88. It is possible that results may differ if reverse shoulder arthroplasty were excluded from our patient cohort. This can be an area of future research.

CONCLUSION

Although much is known about the long-term hardware and functional complications after TSA, in this study, we have attempted to broaden the understanding of perioperative complications and the associated sequelae. Complications are common after TSA surgery and are related to adverse outcomes. In the setting of healthcare changes, the surgeon and the patient must understand the cause, types, incidence, and outcomes of medical and surgical complications after surgery. This allows for more accurate “standard of care” metrics. Further large-volume multicenter studies are needed to gain further insight into the short- and long-term outcomes of TSA.

ABSTRACT

There is a paucity of evidence describing the types and rates of postoperative complications following total shoulder arthroplasty (TSA). We sought to analyze the complications following TSA and determine their effects on described outcome measures.

Using discharge data from the weighted Nationwide Inpatient Sample from 2006 to 2010, patients who underwent primary TSA were identified. The prevalence of specific complications was identified using the International Classification of Diseases, 9th Revision, Clinical Modification (ICD-9-CM) codes. The data from this database represent events occurring during admission, prior to discharge. The associations between patient characteristics, complications, and outcomes of TSA were evaluated. The specific outcomes analyzed in this study were mortality and length of stay (LOS).

A total of 125,766 patients were identified. The rate of complication after TSA was 6.7% (8457 patients). The most frequent complications were respiratory, renal, and cardiac, occurring in 2.9%, 0.8%, and 0.8% of cases, respectively. Increasing age and total number of preoperative comorbidities significantly increased the likelihood of having a complication. The prevalence of postoperative shock and central nervous system, cardiac, vascular, and respiratory complications was significantly higher in patients who suffered postoperative mortality (88 patients; 0.07% mortality rate) than in those who survived surgery (P < 0.0001). In terms of LOS, shock and infectious and vascular complications most significantly increased the length of hospitalization.

Postoperative complications following TSA are not uncommon and occur in >6% of patients. Older patients and certain comorbidities are associated with complications after surgery. These complications are associated with postoperative mortality and increased LOS.

Continue to: Total shoulder arthroplasty...

Total shoulder arthroplasty (TSA) provides a predictably high level of satisfaction with survival as high as 92% at 15 years.¹ As implant instrumentation and surgical technique and understanding have improved, the frequency of TSAs being performed has also increased.² Although there are enough data on long-term surgical complications following TSA,^1,3-6 there is a paucity of evidence delineating the incidence and types of postoperative complications during hospitalization. Several current issues motivate the improved understanding of TSA, including the increasing number of TSAs being performed, the desire to improve quality of care, and the desire to create financially efficient healthcare.

The purpose of this study is to detail the postoperative complications that occur following TSA using a large national database. Specifically, our goals are to determine the incidence and types of complications after shoulder arthroplasty, determine the patient factors that are associated with these complications, and evaluate the effects of these complications on postoperative in-hospital mortality and length of stay (LOS). Our hypothesis is that there would be a correlation between specific patient factors and complications and that these complications would adversely correlate to patient postoperative outcomes.

METHODS

DESIGN

We conducted a retrospective analysis of TSAs captured by the Nationwide Inpatient Sample (NIS) database between 2006 and 2010. The NIS is the largest all-payer inpatient database that is currently available to the public in the United States.⁷

The NIS is a part of the Healthcare Cost and Utilization Project funded by the Agency for Healthcare Research and Quality (AHRQ) and the US Department of Health and Human Services. The NIS database is designed to approximate a 20% sample of US hospitals and the patients they serve, including community, academic, general, and specialty-specific hospitals such as orthopedic hospitals.⁷ The 2010 update of the NIS database contains discharge data from 1051 hospitals across 45 states, with a representative sample of >39 million inpatient hospital stays.⁷ The NIS database and its data sources have been independently validated and assessed for quality each year since 1988.⁸Furthermore, comparative analysis of multiple database elements and distributions has been validated against standard norms, including the National Hospital Discharge Survey.⁹ The NIS database has been used in numerous published studies.^2,10,11

PATIENT SELECTION

The yearly NIS databases from 2006 to 2010 were compiled. Patients aged ≥40 years who underwent a TSA were identified using the International Classification of Diseases, 9th Revision (ICD-9), procedural code 81.80. Exclusion criteria were patients with a primary or a secondary diagnosis of humeral or scapular fracture, chronic osteomyelitis, rheumatologic diseases, or evidence of concurrent malignancy (Figure 1).

Native to NIS are patient demographics, including age, sex, and race. Patient comorbidities as described by Elixhauser and colleagues¹² are also included in the database.

Continue to: OUTCOMES...

 

 

OUTCOMES

The primary outcome of this study was a description of the type and frequency of postoperative complications of TSA. To conduct this analysis, we queried the TSA cohort for specific ICD-9 codes representing acute cardiac, central nervous system, infectious, gastrointestinal, genitourinary, postoperative shock, renal, respiratory, surgical, vascular, and wound complications. The ICD-9 codes used to identify complications were modeled according to previous literature on various surgical applications and were further parsed to reflect only acute postoperative diagnoses^13-15(see the Appendix for the comprehensive list of ICD-9 codes).

Two additional outcomes were analyzed, including postoperative mortality and LOS. Postoperative mortality was defined as death occurring prior to discharge. We calculated the average LOS among the complication and the noncomplication cohort.

STATISTICAL ANALYSIS

Patient demographics and target outcomes of the study were analyzed by frequency distribution. Where applicable, the chi-square and the Student’s t tests were used to confirm the statistical difference for dichotomous and continuous variables, respectively. Multivariate regressions were performed after controlling for possible clustering of the data using a generalized estimating equation following a previous analytical methodology.^16-20 The results are reported with odds ratios and 95% confidence intervals where applicable, all statistical tests with P ≤ 0.05 were considered to be significant, and all statistical tests were two-sided. We conducted all analyses using SAS, version 9.2 (SAS Institute).

RESULTS

From 2006 to 2010, a weighted sample of 141,973 patients was found to undergo a TSA. After applying our inclusion and exclusion criteria, our study cohort consisted of 125,766 patients (Figure 1).

Continue to: OVERALL TSA COHORT DEMOGRAPHICS...

 

 

OVERALL TSA COHORT DEMOGRAPHICS

The average age of the TSA cohort was 69.4 years (standard deviation [SD], 21.20), and 54.1% were females. The cohort had significant comorbidities, with 83.3% of them having at least 1 comorbidity at the time of surgery. Specifically, 31.3% of the patients had 1 comorbidity, 26.5% had 2 comorbidities, and 25.4% had ≥3 comorbidities. Hypertension was the most common comorbidity present in 66.2% of patients, and diabetes was the second most common comorbidity with a prevalence of 16.8%.

COMPLICATION COHORT DEMOGRAPHICS

An overall postoperative complication rate of 6.7% (weighted sample of 8457 patients) was noted in the overall TSA cohort. The TSA cohort was dichotomized into patients who suffered at least 1 complication (weighted, n = 8457) and patients undergoing routine TSAs (weighted, n = 117,308). The average age was significantly higher in the complication vs routine cohort (71.38 vs 69.27 years, P < 0.0001). Similarly, there were significantly more comorbidities (2.51 vs 1.71, P < 0.0001) in the complication cohort.

COMPLICATIONS

We noted a complication rate of 6.7% (weighted sample of 8457 patients). A single complication was noted in 5% of these patients, whereas 1.3% and 0.4% of the patients had 2 and ≥3 complications, respectively. Respiratory abnormalities (2.9%), acute renal failure (0.8%), and cardiac complications (0.8%) were the most prevalent complications after TSA. The list of complications is detailed in Figure 2. Logistic regression analysis of patient characteristics predicting complications showed that advanced age (odds ratio [OR], 2.1 in those aged ≥85 years) and increasing number of comorbidities (≥3; OR, 3.5) were most significant in predicting complications (all P < 0.0001) (Figure 3). Despite the ubiquity of hypertension in this patient population, it was not a significant predictor of complication (OR, 0.9); in contrast, pulmonary disorders (OR, 5.1) and fluid and electrolyte disorders (4.0) were most strongly associated with the development of a postoperative complication after surgery (Figure 4).

EFFECT OF COMPLICATIONS ON LOS

The average length of hospitalization was 2.3 days (95% confidence interval, 2.22-2.25) among the entire cohort. The average LOS was longer in the complication cohort (3.9 days) than in patients who did not have a complication (2.1 days, P < 0.0001). Of the specific complications noted, hemodynamic shock (11.8 days); infectious, most commonly pneumonia (7.6 days); and vascular complications (6.9 days) were associated with the longest hospitalizations. This result is summarized in Figure 5.

MORTALITY

An overall postoperative (in-house) mortality rate of 0.07% was noted (weighted, n = 88). Comparison between the patient cohort that died vs those who survived TSA resulted in significant differences in the rates of complications. Complications that were most significantly different between the cohorts included cardiac (60.47% vs 0.75%, P < 0.0001), postoperative shock (26.61% vs 0.04%, P < 0.0001), and respiratory complications (43.1% vs 2.8%, P < 0.0001). It is important to note that the overall rate of postoperative shock was exceedingly low in the TSA cohort, but it was highly prevalent in the mortality cohort, occurring in 26.61% of patients. A summary of the mortality statistics is presented in Figure 6.

Continue to: DISCUSSION...

 

 

DISCUSSION

TSA continues to be associated with high levels of satisfaction;¹ as a result, its incidence is increasing.² As our understanding and efficiency improves nationally, it is imperative that we determine the short-term and longer-term outcomes and complications. In addition, the factors that may affect prognosis must be elucidated to provide a more individualized and effective standard of care. To date, most of the outcome studies of TSA have evaluated long-term outcomes and specific implant-related complications.^1,5,6,21,22 Our intent was to evaluate the complications that occur in the postoperative period and their effect on unique “patient care” outcomes. With knowledge of these complications and the predisposing factors, we can better assess patients, risk-stratify, and provide appropriate guidelines.

We noted that complications occurring after TSA are not uncommon, with >6% of patients suffering a postoperative complication. In this study, the number of complications noted was associated with worse patient outcomes. In addition, we noted that patients undergoing a TSA have a significant burden of comorbidities; however, hematologic and fluid disorders (eg, iron deficiency anemia, pulmonary circulatory disorders, and fluid imbalances) were most important in predicting postoperative complications.

Increased LOS in the hospital after TSA was associated with the occurrence of complications. Of all noted complications, shock and infectious and vascular complications led to the longest hospitalizations. Hospital-acquired pneumonia was the most common infectious etiology, while pulmonary embolism and deep vein thrombosis were the most consistent vascular complications. Although seldom studied in the TSA population, a similar finding has been noted in patients after THA. O’Malley and colleagues,²³ using the American College of Surgeon’s National Surgical Quality Improvement Program database, identified independent factors that were associated with complications and average prolonged LOS. They noted that the occurrence of major complications was associated with a prolonged LOS. Some, but not all the major complications, included organ space infection, cardiac events, pneumonia, and venous thromboembolic events.²³ Therefore, attempts to limit the amount of time spent in hospitals and control the associated costs must focus on managing the incidence of complications.

Postoperative mortality after TSA was uncommon, occurring in 0.07% of the patients in this study. The low incidence of mortality noted in this study is probably related to the fact that our data represent mortality, whereas in the hospital and, unlike most mortality studies, it does not account for patient demise that may occur in the months after surgery. Other reports have noted that mortality occurs in <1.5% of these patients.^24-28 Singh and colleagues²⁵ observed in their evaluation of perioperative mortality after TSA a mortality rate of 0.8% with 90 days after 4380 shoulder replacements performed at their institution. Using multivariate analysis, they were able to identify associations between mortality and increasing American Society of Anesthesiology (ASA) class and Charlson Comorbidity Index. These results in relation to ours would indicate that the majority of patients who die after shoulder arthroplasty do so after initial discharge. Although we could not determine a causal relationship between mortality and patient comorbidities, we noted that certain complications strongly correlated with mortality. In patients who died, there was a relatively high incidence of cardiac (60.5%) and respiratory (43.1%) complications. Similarly, although postoperative shock was almost nonexistent in the patients who survived surgery (0.04%), it was much more common in the patients who suffered mortality (26.6%).

This study is not without limitations. Data were extracted from a national database, therefore precluding the inclusion of specific details of surgery and functional assessment. Inherent to ICD-9 coding, we were unable to assess the exact detail and severity of complications. For instance, we cannot be certain what criteria were used to define “acute renal failure” for each patient. This study is retrospective in nature and therefore adequate randomization and standardization of patients is not possible. Similarly, the nature of the database may not allow for exacting our inclusion and exclusion criteria. However, the large sample size of the patient population lessens the chance of potential biases and type 2 errors. Prior to October 2010, reverse shoulder arthroplasty was coded under the ICD-9procedural code 81.80 as TSA. Therefore, there is some overlap between TSA and reverse shoulder arthroplasty in our data. Reverse shoulder arthroplasty is now coded under ICD-9 procedural code 81.88. It is possible that results may differ if reverse shoulder arthroplasty were excluded from our patient cohort. This can be an area of future research.

CONCLUSION

Although much is known about the long-term hardware and functional complications after TSA, in this study, we have attempted to broaden the understanding of perioperative complications and the associated sequelae. Complications are common after TSA surgery and are related to adverse outcomes. In the setting of healthcare changes, the surgeon and the patient must understand the cause, types, incidence, and outcomes of medical and surgical complications after surgery. This allows for more accurate “standard of care” metrics. Further large-volume multicenter studies are needed to gain further insight into the short- and long-term outcomes of TSA.

ABSTRACT

The objective of this study is to determine the reproducibility and feasibility of using 3-dimensional (3-D) computer simulation of proximal humerus fracture computed tomography (CT) scans for fracture reduction. We hypothesized that anatomic reconstruction with 3-D models would be anatomically accurate and reproducible.

Preoperative CT scans of 28 patients with 3- and 4-part (AO classification 11-B1, 11-B2, 11-C1, 11-C2) proximal humerus fractures who were treated by hemiarthroplasty were converted into 3-D computer models. The displaced fractured fragments were anatomically reduced with computer simulation by 2 fellowship-trained shoulder surgeons, and measurements were made of the reconstructed proximal humerus.

The measurements of the reconstructed models had very good to excellent interobserver and intraobserver reliability. The reconstructions of these humerus fractures showed interclass correlation coefficients ranging from 0.71 to 0.93 between 1 observer and from 0.82 to 0.98 between 2 different observers. The fracture reduction was judged against normal proximal humerus geometry to determine reduction accuracy.

The 3-D modeling techniques used to reconstruct 3- and 4-part proximal humerus fractures were reliable and accurate. This technique of modeling and reconstructing proximal humerus fractures could be used to enhance the preoperative planning of open reduction and internal fixation or hemiarthroplasty for 3- and 4-part proximal humerus fractures.

The treatment of proximal humerus fractures is influenced by multiple factors, including patient age, associated injuries, bone quality, and fracture pattern. Three- and 4-part fractures are among the more severe of these fractures, which may result in vascular compromise to the humeral head, leading to avascular necrosis. Surgical goals for the management of these fractures are to optimize functional outcomes by re-creating a stable construct with a functional rotator cuff by open reduction and internal fixation (ORIF), hemiarthroplasty with tuberosity ORIF, or reverse shoulder replacement. Achieving a good outcome following hemiarthroplasty is dependent on many factors, including anatomic tuberosity healing and component positioning.^1,2,3 Repairing the greater tuberosity in a near-anatomic position has been shown to greatly affect the results of hemiarthroplasty for fracture.^3,4

Continue to: Three-dimensional (3-D) modeling...

METHODS

After Institutional Review Board approval was obtained, we reviewed the medical records of consecutive patients with a diagnosis of proximal humeral fracture and the treatment codes for hemiarthroplasty from 2000 to 2013. Inclusion criteria included 3- and 4-part fractures (AO classifications 11-B1, 11-B2, 11-C1, 11-C2). CT scans with insufficient quality to differentiate bone from soft tissue (inadequate signal-to-noise ratio) were excluded from the study. A total of 28 patients with adequate CT scans met the criteria for inclusion in this study.

The CT scan protocol included 0.5-mm axial cuts with inclusion of the proximal humerus in the Digital Imaging and Communications in Medicine format. These CT scans were converted into patient-specific 3-D computer models of the shoulder using Mimics software (Materialise Inc.). The use of this software to produce anatomically accurate models has previously been verified in a shoulder model.^6,7 The tuberosity fragments were then individually separated from each other using the voxel-selecting capabilities of 3-D software and manipulated with translation and rotation for anatomic reduction (Figures 1A-1D, Figure 2).

The de-identified anatomically reconstructed shoulder models were then uploaded into Materialise’s Magics rapid prototyping software, and a user-defined humeral Cartesian coordinate system was defined with anatomic landmarks as reference points to standardize the position of each model (Figure 3).^8,9 

A series of measurements were made on these models to assess the validity and reliability of the reassembly. The bicipital groove at the anatomic neck was used to measure humeral head version as described by Kummer and colleagues.¹⁰ The head-shaft angle, humeral head-greater tuberosity distance, humeral head-bicipital groove angle, and posterior and medial humeral head offset were measured directly on the reconstructed humerus.

Continue to: Two fellowship-trained shoulder...

STATISTICS

The measured dimensions of the 28 reassembled proximal humeri models were averaged across all trials between the 2 fellowship-trained surgeons and compared with the range of normal dimensions of a healthy proximal humerus using the 2 one-sided tests (TOST) method for equivalence between 2 means given a range. The interobserver and intraobserver reliabilities were quantified using the interclass correlation coefficient. An excellent correlation was defined as a correlation coefficient >0.81; very good was defined as 0.61 to 0.80; and good was defined as 0.41 to 0.60.

RESULTS

Of the patients studied, 9 (32.1%) were male, and the average age at the time of CT scanning was 72 years. Of the 28 patients with fracture, 18 (64.2%) had 3-part fractures (AO classifications 11-B1, 11-B2), and 10 (35.8%) had 4-part fractures (AO classifications 11-C1, 11-C2). When examining the location of the intertubercular fracture line, we found that 13 (46.4%) fractures went through the bicipital groove. Of the remaining fracture lines, 9 (32.1%) extended into the greater tuberosity and 6 (21.4%) extended into the lesser tuberosity.

All users were able to reconstruct all 28 fractures using this technique. The average measured dimensions fell within the range of dimensions of a normal healthy proximal humerus specified in the literature to within a 95% confidence interval using the TOST for equivalence, in which we compared measured values with ranges reported in the literature (Table).^11,12,13 

Table. Dimensions of Proximal Humerus Geometry

The reconstructions of these humerus fractures showed intraclass correlation coefficients ranging from 0.71 to 0.93 in 1 observer and interclass correlation coefficients from 0.82 to 0.98 between 2 different observers (Table).

DISCUSSION

This study demonstrates that it is feasible to reliably and accurately reconstruct the original anatomy of the proximal humerus by using 3-D computer modeling of proximal humerus fractures. Poor outcomes after hemiarthroplasty for proximal humerus fractures are mostly related to tuberosity malpositioning, resorption, or failure of fixation and resultant dysfunction of the rotator cuff.^14,15,16 These studies highlight the importance of accurate tuberosity reduction during surgical care of these fractures.

Continue to: The 3-D computer model...

Overreduction of greater tuberosity to create cortical overlap with the lateral shaft may be used to promote bony union. As a result of this distalization, there may be extra strains placed on the rotator cuff, making the patient more prone to rotator cuff tear, as well as improperly balancing the dynamic stabilizers of the shoulder. Poor clinical outcomes in hemiarthroplasty for proximal humerus fractures have been correlated with a greater tuberosity placed distal relative to the humeral head by 1 cm in a study² and by 2 cm in another.³

This study has several limitations. The first is the assumption that our injured patients had preinjury proximal humerus geometry within the range of normal dimensions of a healthy humerus. Unfortunately, because we were unable to obtain CT scans of the contralateral shoulder, we had to use standard proximal humerus geometry as the control. Another limitation, inherent in the technique, is that only cortical and dense trabecular bone was modeled, so that comminuted or osteoporotic bone was not well modeled. This study did not correlate the findings from these models with clinical outcomes. A prospective study is needed to evaluate the impact of this 3-D modeling on fracture reductions and clinical outcomes.

This study demonstrates that patient-specific modeling of proximal humerus fracture 3-D CT scans may help surgeons reliably and accurately reconstruct fractures. This technique may have utility in the preoperative planning of tuberosity fracture reduction and hemiarthroplasty. It gives surgeons the ability to visualize fracture fragments, and the process of reconstructing the fragments may help surgeons understand the required maneuvers for reduction at the time of surgery. This technique also provides dimensions of the patient’s native humerus, thus potentially improving the anatomic accuracy of the reduction or hemiarthroplasty reconstruction. With the new trend toward patient-specific instrumentation, this study also provides a means of planning the size of the humeral prostheses as well as the version relative to the biceps groove and intertubercular fracture line.

CONCLUSION

This study demonstrates the feasibility of using 3-D computer modeling of complex proximal humerus fractures in anatomic reconstruction. These techniques of computer-simulated 3-D models are valid and reliable. We believe that this technique of modeling and reconstructing proximal humerus fractures could be used to enhance the preoperative planning of hemiarthroplasty for 3- and 4-part proximal humerus fractures by providing improved understanding of the patient’s native humeral geometry and tuberosity reduction.

ABSTRACT

The objective of this study is to determine the reproducibility and feasibility of using 3-dimensional (3-D) computer simulation of proximal humerus fracture computed tomography (CT) scans for fracture reduction. We hypothesized that anatomic reconstruction with 3-D models would be anatomically accurate and reproducible.

Preoperative CT scans of 28 patients with 3- and 4-part (AO classification 11-B1, 11-B2, 11-C1, 11-C2) proximal humerus fractures who were treated by hemiarthroplasty were converted into 3-D computer models. The displaced fractured fragments were anatomically reduced with computer simulation by 2 fellowship-trained shoulder surgeons, and measurements were made of the reconstructed proximal humerus.

The measurements of the reconstructed models had very good to excellent interobserver and intraobserver reliability. The reconstructions of these humerus fractures showed interclass correlation coefficients ranging from 0.71 to 0.93 between 1 observer and from 0.82 to 0.98 between 2 different observers. The fracture reduction was judged against normal proximal humerus geometry to determine reduction accuracy.

The 3-D modeling techniques used to reconstruct 3- and 4-part proximal humerus fractures were reliable and accurate. This technique of modeling and reconstructing proximal humerus fractures could be used to enhance the preoperative planning of open reduction and internal fixation or hemiarthroplasty for 3- and 4-part proximal humerus fractures.

The treatment of proximal humerus fractures is influenced by multiple factors, including patient age, associated injuries, bone quality, and fracture pattern. Three- and 4-part fractures are among the more severe of these fractures, which may result in vascular compromise to the humeral head, leading to avascular necrosis. Surgical goals for the management of these fractures are to optimize functional outcomes by re-creating a stable construct with a functional rotator cuff by open reduction and internal fixation (ORIF), hemiarthroplasty with tuberosity ORIF, or reverse shoulder replacement. Achieving a good outcome following hemiarthroplasty is dependent on many factors, including anatomic tuberosity healing and component positioning.^1,2,3 Repairing the greater tuberosity in a near-anatomic position has been shown to greatly affect the results of hemiarthroplasty for fracture.^3,4

Continue to: Three-dimensional (3-D) modeling...

METHODS

After Institutional Review Board approval was obtained, we reviewed the medical records of consecutive patients with a diagnosis of proximal humeral fracture and the treatment codes for hemiarthroplasty from 2000 to 2013. Inclusion criteria included 3- and 4-part fractures (AO classifications 11-B1, 11-B2, 11-C1, 11-C2). CT scans with insufficient quality to differentiate bone from soft tissue (inadequate signal-to-noise ratio) were excluded from the study. A total of 28 patients with adequate CT scans met the criteria for inclusion in this study.

The CT scan protocol included 0.5-mm axial cuts with inclusion of the proximal humerus in the Digital Imaging and Communications in Medicine format. These CT scans were converted into patient-specific 3-D computer models of the shoulder using Mimics software (Materialise Inc.). The use of this software to produce anatomically accurate models has previously been verified in a shoulder model.^6,7 The tuberosity fragments were then individually separated from each other using the voxel-selecting capabilities of 3-D software and manipulated with translation and rotation for anatomic reduction (Figures 1A-1D, Figure 2).

The de-identified anatomically reconstructed shoulder models were then uploaded into Materialise’s Magics rapid prototyping software, and a user-defined humeral Cartesian coordinate system was defined with anatomic landmarks as reference points to standardize the position of each model (Figure 3).^8,9 

A series of measurements were made on these models to assess the validity and reliability of the reassembly. The bicipital groove at the anatomic neck was used to measure humeral head version as described by Kummer and colleagues.¹⁰ The head-shaft angle, humeral head-greater tuberosity distance, humeral head-bicipital groove angle, and posterior and medial humeral head offset were measured directly on the reconstructed humerus.

Continue to: Two fellowship-trained shoulder...

STATISTICS

The measured dimensions of the 28 reassembled proximal humeri models were averaged across all trials between the 2 fellowship-trained surgeons and compared with the range of normal dimensions of a healthy proximal humerus using the 2 one-sided tests (TOST) method for equivalence between 2 means given a range. The interobserver and intraobserver reliabilities were quantified using the interclass correlation coefficient. An excellent correlation was defined as a correlation coefficient >0.81; very good was defined as 0.61 to 0.80; and good was defined as 0.41 to 0.60.

RESULTS

Of the patients studied, 9 (32.1%) were male, and the average age at the time of CT scanning was 72 years. Of the 28 patients with fracture, 18 (64.2%) had 3-part fractures (AO classifications 11-B1, 11-B2), and 10 (35.8%) had 4-part fractures (AO classifications 11-C1, 11-C2). When examining the location of the intertubercular fracture line, we found that 13 (46.4%) fractures went through the bicipital groove. Of the remaining fracture lines, 9 (32.1%) extended into the greater tuberosity and 6 (21.4%) extended into the lesser tuberosity.

All users were able to reconstruct all 28 fractures using this technique. The average measured dimensions fell within the range of dimensions of a normal healthy proximal humerus specified in the literature to within a 95% confidence interval using the TOST for equivalence, in which we compared measured values with ranges reported in the literature (Table).^11,12,13 

Table. Dimensions of Proximal Humerus Geometry

The reconstructions of these humerus fractures showed intraclass correlation coefficients ranging from 0.71 to 0.93 in 1 observer and interclass correlation coefficients from 0.82 to 0.98 between 2 different observers (Table).

DISCUSSION

This study demonstrates that it is feasible to reliably and accurately reconstruct the original anatomy of the proximal humerus by using 3-D computer modeling of proximal humerus fractures. Poor outcomes after hemiarthroplasty for proximal humerus fractures are mostly related to tuberosity malpositioning, resorption, or failure of fixation and resultant dysfunction of the rotator cuff.^14,15,16 These studies highlight the importance of accurate tuberosity reduction during surgical care of these fractures.

Continue to: The 3-D computer model...

Overreduction of greater tuberosity to create cortical overlap with the lateral shaft may be used to promote bony union. As a result of this distalization, there may be extra strains placed on the rotator cuff, making the patient more prone to rotator cuff tear, as well as improperly balancing the dynamic stabilizers of the shoulder. Poor clinical outcomes in hemiarthroplasty for proximal humerus fractures have been correlated with a greater tuberosity placed distal relative to the humeral head by 1 cm in a study² and by 2 cm in another.³

This study has several limitations. The first is the assumption that our injured patients had preinjury proximal humerus geometry within the range of normal dimensions of a healthy humerus. Unfortunately, because we were unable to obtain CT scans of the contralateral shoulder, we had to use standard proximal humerus geometry as the control. Another limitation, inherent in the technique, is that only cortical and dense trabecular bone was modeled, so that comminuted or osteoporotic bone was not well modeled. This study did not correlate the findings from these models with clinical outcomes. A prospective study is needed to evaluate the impact of this 3-D modeling on fracture reductions and clinical outcomes.

This study demonstrates that patient-specific modeling of proximal humerus fracture 3-D CT scans may help surgeons reliably and accurately reconstruct fractures. This technique may have utility in the preoperative planning of tuberosity fracture reduction and hemiarthroplasty. It gives surgeons the ability to visualize fracture fragments, and the process of reconstructing the fragments may help surgeons understand the required maneuvers for reduction at the time of surgery. This technique also provides dimensions of the patient’s native humerus, thus potentially improving the anatomic accuracy of the reduction or hemiarthroplasty reconstruction. With the new trend toward patient-specific instrumentation, this study also provides a means of planning the size of the humeral prostheses as well as the version relative to the biceps groove and intertubercular fracture line.

CONCLUSION

This study demonstrates the feasibility of using 3-D computer modeling of complex proximal humerus fractures in anatomic reconstruction. These techniques of computer-simulated 3-D models are valid and reliable. We believe that this technique of modeling and reconstructing proximal humerus fractures could be used to enhance the preoperative planning of hemiarthroplasty for 3- and 4-part proximal humerus fractures by providing improved understanding of the patient’s native humeral geometry and tuberosity reduction.

ABSTRACT

The objective of this study is to determine the reproducibility and feasibility of using 3-dimensional (3-D) computer simulation of proximal humerus fracture computed tomography (CT) scans for fracture reduction. We hypothesized that anatomic reconstruction with 3-D models would be anatomically accurate and reproducible.

Preoperative CT scans of 28 patients with 3- and 4-part (AO classification 11-B1, 11-B2, 11-C1, 11-C2) proximal humerus fractures who were treated by hemiarthroplasty were converted into 3-D computer models. The displaced fractured fragments were anatomically reduced with computer simulation by 2 fellowship-trained shoulder surgeons, and measurements were made of the reconstructed proximal humerus.

The measurements of the reconstructed models had very good to excellent interobserver and intraobserver reliability. The reconstructions of these humerus fractures showed interclass correlation coefficients ranging from 0.71 to 0.93 between 1 observer and from 0.82 to 0.98 between 2 different observers. The fracture reduction was judged against normal proximal humerus geometry to determine reduction accuracy.

The 3-D modeling techniques used to reconstruct 3- and 4-part proximal humerus fractures were reliable and accurate. This technique of modeling and reconstructing proximal humerus fractures could be used to enhance the preoperative planning of open reduction and internal fixation or hemiarthroplasty for 3- and 4-part proximal humerus fractures.

The treatment of proximal humerus fractures is influenced by multiple factors, including patient age, associated injuries, bone quality, and fracture pattern. Three- and 4-part fractures are among the more severe of these fractures, which may result in vascular compromise to the humeral head, leading to avascular necrosis. Surgical goals for the management of these fractures are to optimize functional outcomes by re-creating a stable construct with a functional rotator cuff by open reduction and internal fixation (ORIF), hemiarthroplasty with tuberosity ORIF, or reverse shoulder replacement. Achieving a good outcome following hemiarthroplasty is dependent on many factors, including anatomic tuberosity healing and component positioning.^1,2,3 Repairing the greater tuberosity in a near-anatomic position has been shown to greatly affect the results of hemiarthroplasty for fracture.^3,4

Continue to: Three-dimensional (3-D) modeling...

METHODS

After Institutional Review Board approval was obtained, we reviewed the medical records of consecutive patients with a diagnosis of proximal humeral fracture and the treatment codes for hemiarthroplasty from 2000 to 2013. Inclusion criteria included 3- and 4-part fractures (AO classifications 11-B1, 11-B2, 11-C1, 11-C2). CT scans with insufficient quality to differentiate bone from soft tissue (inadequate signal-to-noise ratio) were excluded from the study. A total of 28 patients with adequate CT scans met the criteria for inclusion in this study.

The CT scan protocol included 0.5-mm axial cuts with inclusion of the proximal humerus in the Digital Imaging and Communications in Medicine format. These CT scans were converted into patient-specific 3-D computer models of the shoulder using Mimics software (Materialise Inc.). The use of this software to produce anatomically accurate models has previously been verified in a shoulder model.^6,7 The tuberosity fragments were then individually separated from each other using the voxel-selecting capabilities of 3-D software and manipulated with translation and rotation for anatomic reduction (Figures 1A-1D, Figure 2).

The de-identified anatomically reconstructed shoulder models were then uploaded into Materialise’s Magics rapid prototyping software, and a user-defined humeral Cartesian coordinate system was defined with anatomic landmarks as reference points to standardize the position of each model (Figure 3).^8,9 

A series of measurements were made on these models to assess the validity and reliability of the reassembly. The bicipital groove at the anatomic neck was used to measure humeral head version as described by Kummer and colleagues.¹⁰ The head-shaft angle, humeral head-greater tuberosity distance, humeral head-bicipital groove angle, and posterior and medial humeral head offset were measured directly on the reconstructed humerus.

Continue to: Two fellowship-trained shoulder...

STATISTICS

The measured dimensions of the 28 reassembled proximal humeri models were averaged across all trials between the 2 fellowship-trained surgeons and compared with the range of normal dimensions of a healthy proximal humerus using the 2 one-sided tests (TOST) method for equivalence between 2 means given a range. The interobserver and intraobserver reliabilities were quantified using the interclass correlation coefficient. An excellent correlation was defined as a correlation coefficient >0.81; very good was defined as 0.61 to 0.80; and good was defined as 0.41 to 0.60.

RESULTS

Of the patients studied, 9 (32.1%) were male, and the average age at the time of CT scanning was 72 years. Of the 28 patients with fracture, 18 (64.2%) had 3-part fractures (AO classifications 11-B1, 11-B2), and 10 (35.8%) had 4-part fractures (AO classifications 11-C1, 11-C2). When examining the location of the intertubercular fracture line, we found that 13 (46.4%) fractures went through the bicipital groove. Of the remaining fracture lines, 9 (32.1%) extended into the greater tuberosity and 6 (21.4%) extended into the lesser tuberosity.

All users were able to reconstruct all 28 fractures using this technique. The average measured dimensions fell within the range of dimensions of a normal healthy proximal humerus specified in the literature to within a 95% confidence interval using the TOST for equivalence, in which we compared measured values with ranges reported in the literature (Table).^11,12,13 

Table. Dimensions of Proximal Humerus Geometry

The reconstructions of these humerus fractures showed intraclass correlation coefficients ranging from 0.71 to 0.93 in 1 observer and interclass correlation coefficients from 0.82 to 0.98 between 2 different observers (Table).

DISCUSSION

This study demonstrates that it is feasible to reliably and accurately reconstruct the original anatomy of the proximal humerus by using 3-D computer modeling of proximal humerus fractures. Poor outcomes after hemiarthroplasty for proximal humerus fractures are mostly related to tuberosity malpositioning, resorption, or failure of fixation and resultant dysfunction of the rotator cuff.^14,15,16 These studies highlight the importance of accurate tuberosity reduction during surgical care of these fractures.

Continue to: The 3-D computer model...

Overreduction of greater tuberosity to create cortical overlap with the lateral shaft may be used to promote bony union. As a result of this distalization, there may be extra strains placed on the rotator cuff, making the patient more prone to rotator cuff tear, as well as improperly balancing the dynamic stabilizers of the shoulder. Poor clinical outcomes in hemiarthroplasty for proximal humerus fractures have been correlated with a greater tuberosity placed distal relative to the humeral head by 1 cm in a study² and by 2 cm in another.³

This study has several limitations. The first is the assumption that our injured patients had preinjury proximal humerus geometry within the range of normal dimensions of a healthy humerus. Unfortunately, because we were unable to obtain CT scans of the contralateral shoulder, we had to use standard proximal humerus geometry as the control. Another limitation, inherent in the technique, is that only cortical and dense trabecular bone was modeled, so that comminuted or osteoporotic bone was not well modeled. This study did not correlate the findings from these models with clinical outcomes. A prospective study is needed to evaluate the impact of this 3-D modeling on fracture reductions and clinical outcomes.

This study demonstrates that patient-specific modeling of proximal humerus fracture 3-D CT scans may help surgeons reliably and accurately reconstruct fractures. This technique may have utility in the preoperative planning of tuberosity fracture reduction and hemiarthroplasty. It gives surgeons the ability to visualize fracture fragments, and the process of reconstructing the fragments may help surgeons understand the required maneuvers for reduction at the time of surgery. This technique also provides dimensions of the patient’s native humerus, thus potentially improving the anatomic accuracy of the reduction or hemiarthroplasty reconstruction. With the new trend toward patient-specific instrumentation, this study also provides a means of planning the size of the humeral prostheses as well as the version relative to the biceps groove and intertubercular fracture line.

CONCLUSION

This study demonstrates the feasibility of using 3-D computer modeling of complex proximal humerus fractures in anatomic reconstruction. These techniques of computer-simulated 3-D models are valid and reliable. We believe that this technique of modeling and reconstructing proximal humerus fractures could be used to enhance the preoperative planning of hemiarthroplasty for 3- and 4-part proximal humerus fractures by providing improved understanding of the patient’s native humeral geometry and tuberosity reduction.

Take-Home Points

• The authors have developed a total shoulder glenoid prosthesis that conforms with the humeral head in its center and is nonconforming on its peripheral edge.
• All clinical survey and range of motion parameters demonstrated statistically significant improvements at final follow-up.
• Only 3 shoulders (1.7%) required revision surgery.
• Eighty-six (63%) of 136 shoulders demonstrated no radiographic evidence of glenoid loosening.
• This is the first and largest study that evaluates the clinical and radiographic outcomes of this hybrid shoulder prosthesis.

Fixation of the glenoid component is the limiting factor in modern total shoulder arthroplasty (TSA). Glenoid loosening, the most common long-term complication, necessitates revision in up to 12% of patients.^1-4 By contrast, humeral component loosening is relatively uncommon, affecting as few as 0.34% of patients.⁵ Multiple long-term studies have found consistently high rates (45%-93%) of radiolucencies around the glenoid component.^3,6,7 Although their clinical significance has been debated, radiolucencies around the glenoid component raise concern about progressive loss of fixation.

Since TSA was introduced in the 1970s, complications with the glenoid component have been addressed with 2 different designs: conforming (congruent) and nonconforming. In a congruent articulation, the radii of curvature of the glenoid and humeral head components are identical, whereas they differ in a nonconforming model. Joint conformity is inversely related to glenohumeral translation.⁸ Neer’s original TSA was made congruent in order to limit translation and maximize the contact area. However, this design results in edge loading and a so-called rocking-horse phenomenon, which may lead to glenoid loosening.^9-13 Surgeons therefore have increasingly turned to nonconforming implants. In the nonconforming design, the radius of curvature of the humeral head is smaller than that of the glenoid. Although this design may reduce edge loading,¹⁴ it allows more translation and reduces the relative contact area of the glenohumeral joint. As a result, more contact stress is transmitted to the glenoid component, leading to polyethylene deformation and wear.^15,16

Dual radii of curvature are designed to augment joint stability without increasing component wear. Biomechanical data have indicated that edge loading is not increased by having a central conforming region added to a nonconforming model.¹⁷ The clinical value of this prosthesis, however, has not been determined. Therefore, we conducted a study to describe the intermediate-term clinical and radiographic outcomes of TSAs that use a novel hybrid glenoid component.

Materials and Methods

This study was approved (protocol AAAD3473) by the Institutional Review Board of Columbia University and was conducted in compliance with Health Insurance Portability and Accountability Act (HIPAA) regulations.

Patient Selection

At Columbia University Medical Center, Dr. Bigliani performed 196 TSAs with a hybrid glenoid component (Bigliani-Flatow; Zimmer Biomet) in 169 patients between September 1998 and November 2007. All patients had received a diagnosis of primary glenohumeral arthritis as defined by Neer.¹⁸ Patients with previous surgery such as rotator cuff repair or subacromial decompression were included in our review, and patients with a nonprimary form of arthritis, such as rheumatoid, posttraumatic, or post-capsulorrhaphy arthritis, were excluded.

Operative Technique

For all surgeries, Dr. Bigliani performed a subscapularis tenotomy with regional anesthesia and a standard deltopectoral approach. A partial anterior capsulectomy was performed to increase the glenoid’s visibility. The inferior labrum was removed with a needle-tip bovie while the axillary nerve was being protected with a metal finger or narrow Darrach retractor. After reaming and trialing, the final glenoid component was cemented into place. Cement was placed only in the peg or keel holes and pressurized twice before final implantation. Of the 196 glenoid components, 168 (86%) were pegged and 28 (14%) keeled; in addition,190 of these components were all-polyethylene, whereas 6 had trabecular-metal backing. All glenoid components incorporated the hybrid design of dual radii of curvature. After the glenoid was cemented, the final humeral component was placed in 30° of retroversion. Whenever posterior wear was found, retroversion was reduced by 5° to 10°. The humeral prosthesis was cemented in cases (104/196, 53%) of poor bone quality or a large canal.

After surgery, the patient’s sling was fitted with an abduction pillow and a swathe, to be worn the first 24 hours, and the arm was passively ranged. Patients typically were discharged on postoperative day 2. Then, for 2 weeks, they followed an assisted passive range of motion (ROM) protocol, with limited external rotation, for promotion of subscapularis healing.

Clinical Outcomes

Dr. Bigliani assessed preoperative ROM in all planes. During initial evaluation, patients completed a questionnaire that consisted of the 36-Item Short Form Health Survey^19,20 (SF-36) and the American Shoulder and Elbow Surgeons²¹ (ASES) and Simple Shoulder Test²² (SST) surveys. Postoperative clinical data were collected from office follow-up visits, survey questionnaires, or both. Postoperative office data included ROM, subscapularis integrity testing (belly-press or lift-off), and any complications. Patients with <1 year of office follow-up were excluded. In addition, the same survey questionnaire that was used before surgery was mailed to all patients after surgery; then, for anyone who did not respond by mail, we attempted contact by telephone. Neer criteria were based on patients’ subjective assessment of each arm on a 3-point Likert scale (1 = very satisfied, 2 = satisfied, 3 = dissatisfied). Patients were also asked about any specific complications or revision operations since their index procedure.

Physical examination and office follow-up data were obtained for 129 patients (148/196 shoulders, 76% follow-up) at a mean of 3.7 years (range 1.0-10.2 years) after surgery. Surveys were completed by 117 patients (139/196 shoulders, 71% follow-up) at a mean of 5.1 years (range, 1.6-11.2 years) after surgery. Only 15 patients had neither 1 year of office follow-up nor a completed questionnaire. The remaining 154 patients (178/196 shoulders, 91% follow-up) had clinical follow-up with office, mail, or telephone questionnaire at a mean of 4.8 years (range, 1.0-11.2 years) after surgery. This cohort of patients was used to determine rates of surgical revisions, subscapularis tears, dislocations, and other complications.

Radiographic Outcomes

Patients were included in the radiographic analysis if they had a shoulder radiograph at least 1 year after surgery. One hundred nineteen patients (136/196 shoulders, 69% follow-up) had radiographic follow-up at a mean of 3.7 years (range, 1.0-9.4 years) after surgery.

Statistical Analysis

Statistical analysis was performed with Stata Version 10.0. Paired t tests were used to compare preoperative and postoperative numerical data, including ROM and survey scores. We calculated 95% confidence intervals (CIs) and set statistical significance at P < .05. For qualitative measures, the Fisher exact test was used. Survivorship analysis was performed according to the Kaplan-Meier method, with right-censored data for no event or missing data.²⁵

Results

Clinical Analysis of Demographics

In demographics, the clinical and radiographic patient subgroups were similar to each other and to the overall study population (Table 2). Of 196 patients overall, 16 (8%) had a concomitant rotator cuff repair, and 27 (14%) underwent staged bilateral shoulder arthroplasties.

Clinical Analysis of ROM and Survey Scores

Operative shoulder ROM in forward elevation, external rotation at side, external rotation in abduction, and internal rotation all showed statistically significant (P < .001) improvement from before surgery to after surgery. Over 3.7 years, mean (SD) forward elevation improved from 107.3° (34.8°) to 159.0° (29.4°), external rotation at side improved from 20.4° (16.7°) to 49.4° (11.3°), and external rotation in abduction improved from 53.7° (24.3°) to 84.7° (9.1°). Internal rotation improved from a mean (SD) vertebral level of S1 (6.0 levels) to T9 (3.7 levels).

All validated survey scores also showed statistically significant (P < .001) improvement from before surgery to after surgery. Over 5.1 years, mean (SD) SF-36 scores improved from 64.9 (13.4) to 73.6 (17.1), ASES scores improved from 41.1 (22.5) to 82.7 (17.7), SST scores improved from 3.9 (2.8) to 9.7 (2.2), and visual analog scale pain scores improved from 5.6 (3.2) to 1.4 (2.1). Of 139 patients with follow-up, 130 (93.5%) were either satisfied or very satisfied with their TSA, and only 119 (86%) were either satisfied or very satisfied with the nonoperative shoulder.

Clinical Analysis of Postoperative Complications

Of the 178 shoulders evaluated for complications, 3 (1.7%) underwent revision surgery. Mean time to revision was 2.3 years (range, 1.5-3.9 years). Two revisions involved the glenoid component, and the third involved the humerus. In one of the glenoid cases, a 77-year-old woman fell and sustained a fracture at the base of the trabecular metal glenoid pegs; her component was revised to an all-polyethylene component, and she had no further complications. In the other glenoid case, a 73-year-old man’s all-polyethylene component loosened after 2 years and was revised to a trabecular metal implant, which loosened as well and was later converted to a hemiarthroplasty. In the humeral case, a 33-year-old man had his 4-year-old index TSA revised to a cemented stem and had no further complications.

Table 4 compares the clinical and radiographic outcomes of patients who required subscapularis repair, capsular shift, or implant revision with the outcomes of all other study patients, and Figure 3 shows Kaplan-Meier survivorship.

Postoperative Radiographic Analysis

Glenoid Component. At a mean of 3.7 years (minimum, 1 year) after surgery, 86 (63%) of 136 radiographically evaluated shoulders showed no glenoid lucencies; the other 50 (37%) showed ≥1 lucency. Of the 136 shoulders, 33 (24%) had a Lazarus score of 1, 15 (11%) had a score of 2, and only 2 (2%) had a score of 3. None of the shoulders had a score of 4 or 5.

Humeral Component. Of the 136 shoulders, 91 (67%) showed no lucencies in any of the 8 humeral stem zones; the other 45 (33%) showed 1 to 3 lucencies. Thirty (22%) of the 136 shoulders had 1 stem lucency zone, 8 (6%) had 2, and 3 (2%) had 3. None of the shoulders had >3 periprosthetic zones with lucent lines.

Discussion

In this article, we describe a hybrid glenoid TSA component with dual radii of curvature. Its central portion is congruent with the humeral head, and its peripheral portion is noncongruent and larger. The most significant finding of our study is the low rate (1.1%) of glenoid component revision 4.8 years after surgery. This rate is the lowest that has been reported in a study of ≥100 patients. Overall implant survival appeared as an almost flat Kaplan-Meir curve. We attribute this low revision rate to improved biomechanics with the hybrid glenoid design. 

Symptomatic glenoid component loosening is the most common TSA complication.^1,26-28 In a review of 73 Neer TSAs, Cofield7 found glenoid radiolucencies in 71% of patients 3.8 years after surgery. Radiographic evidence of loosening, defined as component migration, or tilt, or a circumferential lucency 1.5 mm thick, was present in another 11% of patients, and 4.1% developed symptomatic loosening that required glenoid revision. In a study with 12.2-year follow-up, Torchia and colleagues³ found rates of 84% for glenoid radiolucencies, 44% for radiographic loosening, and 5.6% for symptomatic loosening that required revision. In a systematic review of studies with follow-up of ≥10 years, Bohsali and colleagues²⁷ found similar lucency and radiographic loosening rates and a 7% glenoid revision rate. These data suggest glenoid radiolucencies may progress to component loosening.

Degree of joint congruence is a key factor in glenoid loosening. Neer’s congruent design increases the contact area with concentric loading and reduces glenohumeral translation, which leads to reduced polyethylene wear and improved joint stability. In extreme arm positions, however, humeral head subluxation results in edge loading and a glenoid rocking-horse effect.^{9-13,17,29-31} Conversely, nonconforming implants allow increased glenohumeral translation without edge loading,¹⁴ though they also reduce the relative glenohumeral contact area and thus transmit more contact stress to the glenoid.^16,17 A hybrid glenoid component with central conforming and peripheral nonconforming zones may reduce the rocking-horse effect while maximizing ROM and joint stability. Wang and colleagues32 studied the biomechanical properties of this glenoid design and found that the addition of a central conforming region did not increase edge loading.

Additional results from our study support the efficacy of a hybrid glenoid component. Patients’ clinical outcomes improved significantly. At 5.1 years after surgery, 93.5% of patients were satisfied or very satisfied with their procedure and reported less satisfaction (86%) with the nonoperative shoulder. Also significant was the reduced number of radiolucencies. At 3.7 years after surgery, the overall percentage of shoulders with ≥1 glenoid radiolucency was 37%, considerably lower than the 82% reported by Cofield7 and the rates in more recent studies.^3,16,33-36 Of the 178 shoulders in our study, 10 (5.6%) had subscapularis tears, and 6 (3.4%) of 178 had these tears surgically repaired. This 3.4% compares favorably with the 5.9% (of 119 patients) found by Miller and colleagues37 28 months after surgery. Of our 178 shoulders, 27 (15.2%) had clinically significant postoperative complications; 18 (10.1%) of the 178 had these complications surgically treated, and 9 (5.1%) had them managed nonoperatively. Bohsali and colleagues²⁷ systematically reviewed 33 TSA studies and found a slightly higher complication rate (16.3%) 5.3 years after surgery. Furthermore, in our study, the 11 patients who underwent revision, capsular shift, or subscapularis repair had final outcomes comparable to those of the rest of our study population.

Our study had several potential weaknesses. First, its minimum clinical and radiographic follow-up was 1 year, whereas most long-term TSA series set a minimum of 2 years. We used 1 year because this was the first clinical study of the hybrid glenoid component design, and we wanted to maximize its sample size by reporting on intermediate-length outcomes. Even so, 93% (166/178) of our clinical patients and 83% (113/136) of our radiographic patients have had ≥2 years of follow-up, and we continue to follow all study patients for long-term outcomes. Another weakness of the study was its lack of a uniform group of patients with all the office, survey, complications, and radiographic data. Our retrospective study design made it difficult to obtain such a group without significantly reducing the sample size, so we divided patients into 4 data groups. A third potential weakness was the study’s variable method for collecting complications data. Rates of complications in the 178 shoulders were calculated from either office evaluation or patient self-report by mail or telephone. This data collection method is subject to recall bias, but mail and telephone contact was needed so the study would capture the large number of patients who had traveled to our institution for their surgery or had since moved away. Fourth, belly-press and lift-off tests were used in part to assess subscapularis function, but recent literature suggests post-TSA subscapularis assessment can be unreliable.³⁸ These tests may be positive in up to two-thirds of patients after 2 years.³⁹ Fifth, the generalizability of our findings to diagnoses such as rheumatoid and posttraumatic arthritis is limited. We had to restrict the study to patients with primary glenohumeral arthritis in order to minimize confounders.

This study’s main strength is its description of the clinical and radiographic outcomes of using a single prosthetic system in operations performed by a single surgeon in a large number of patients. This was the first and largest study evaluating the clinical and radiographic outcomes of this hybrid glenoid implant. Excluding patients with nonprimary arthritis allowed us to minimize potential confounding factors that affect patient outcomes. In conclusion, our study results showed the favorable clinical and radiographic outcomes of TSAs that have a hybrid glenoid component with dual radii of curvature. At a mean of 3.7 years after surgery, 63% of patients had no glenoid lucencies, and, at a mean of 4.8 years, only 1.7% of patients required revision. We continue to follow these patients to obtain long-term results of this innovative prosthesis.

Take-Home Points

• The authors have developed a total shoulder glenoid prosthesis that conforms with the humeral head in its center and is nonconforming on its peripheral edge.
• All clinical survey and range of motion parameters demonstrated statistically significant improvements at final follow-up.
• Only 3 shoulders (1.7%) required revision surgery.
• Eighty-six (63%) of 136 shoulders demonstrated no radiographic evidence of glenoid loosening.
• This is the first and largest study that evaluates the clinical and radiographic outcomes of this hybrid shoulder prosthesis.

Fixation of the glenoid component is the limiting factor in modern total shoulder arthroplasty (TSA). Glenoid loosening, the most common long-term complication, necessitates revision in up to 12% of patients.^1-4 By contrast, humeral component loosening is relatively uncommon, affecting as few as 0.34% of patients.⁵ Multiple long-term studies have found consistently high rates (45%-93%) of radiolucencies around the glenoid component.^3,6,7 Although their clinical significance has been debated, radiolucencies around the glenoid component raise concern about progressive loss of fixation.

Since TSA was introduced in the 1970s, complications with the glenoid component have been addressed with 2 different designs: conforming (congruent) and nonconforming. In a congruent articulation, the radii of curvature of the glenoid and humeral head components are identical, whereas they differ in a nonconforming model. Joint conformity is inversely related to glenohumeral translation.⁸ Neer’s original TSA was made congruent in order to limit translation and maximize the contact area. However, this design results in edge loading and a so-called rocking-horse phenomenon, which may lead to glenoid loosening.^9-13 Surgeons therefore have increasingly turned to nonconforming implants. In the nonconforming design, the radius of curvature of the humeral head is smaller than that of the glenoid. Although this design may reduce edge loading,¹⁴ it allows more translation and reduces the relative contact area of the glenohumeral joint. As a result, more contact stress is transmitted to the glenoid component, leading to polyethylene deformation and wear.^15,16

Dual radii of curvature are designed to augment joint stability without increasing component wear. Biomechanical data have indicated that edge loading is not increased by having a central conforming region added to a nonconforming model.¹⁷ The clinical value of this prosthesis, however, has not been determined. Therefore, we conducted a study to describe the intermediate-term clinical and radiographic outcomes of TSAs that use a novel hybrid glenoid component.

Materials and Methods

This study was approved (protocol AAAD3473) by the Institutional Review Board of Columbia University and was conducted in compliance with Health Insurance Portability and Accountability Act (HIPAA) regulations.

Patient Selection

At Columbia University Medical Center, Dr. Bigliani performed 196 TSAs with a hybrid glenoid component (Bigliani-Flatow; Zimmer Biomet) in 169 patients between September 1998 and November 2007. All patients had received a diagnosis of primary glenohumeral arthritis as defined by Neer.¹⁸ Patients with previous surgery such as rotator cuff repair or subacromial decompression were included in our review, and patients with a nonprimary form of arthritis, such as rheumatoid, posttraumatic, or post-capsulorrhaphy arthritis, were excluded.

Operative Technique

For all surgeries, Dr. Bigliani performed a subscapularis tenotomy with regional anesthesia and a standard deltopectoral approach. A partial anterior capsulectomy was performed to increase the glenoid’s visibility. The inferior labrum was removed with a needle-tip bovie while the axillary nerve was being protected with a metal finger or narrow Darrach retractor. After reaming and trialing, the final glenoid component was cemented into place. Cement was placed only in the peg or keel holes and pressurized twice before final implantation. Of the 196 glenoid components, 168 (86%) were pegged and 28 (14%) keeled; in addition,190 of these components were all-polyethylene, whereas 6 had trabecular-metal backing. All glenoid components incorporated the hybrid design of dual radii of curvature. After the glenoid was cemented, the final humeral component was placed in 30° of retroversion. Whenever posterior wear was found, retroversion was reduced by 5° to 10°. The humeral prosthesis was cemented in cases (104/196, 53%) of poor bone quality or a large canal.

After surgery, the patient’s sling was fitted with an abduction pillow and a swathe, to be worn the first 24 hours, and the arm was passively ranged. Patients typically were discharged on postoperative day 2. Then, for 2 weeks, they followed an assisted passive range of motion (ROM) protocol, with limited external rotation, for promotion of subscapularis healing.

Clinical Outcomes

Dr. Bigliani assessed preoperative ROM in all planes. During initial evaluation, patients completed a questionnaire that consisted of the 36-Item Short Form Health Survey^19,20 (SF-36) and the American Shoulder and Elbow Surgeons²¹ (ASES) and Simple Shoulder Test²² (SST) surveys. Postoperative clinical data were collected from office follow-up visits, survey questionnaires, or both. Postoperative office data included ROM, subscapularis integrity testing (belly-press or lift-off), and any complications. Patients with <1 year of office follow-up were excluded. In addition, the same survey questionnaire that was used before surgery was mailed to all patients after surgery; then, for anyone who did not respond by mail, we attempted contact by telephone. Neer criteria were based on patients’ subjective assessment of each arm on a 3-point Likert scale (1 = very satisfied, 2 = satisfied, 3 = dissatisfied). Patients were also asked about any specific complications or revision operations since their index procedure.

Physical examination and office follow-up data were obtained for 129 patients (148/196 shoulders, 76% follow-up) at a mean of 3.7 years (range 1.0-10.2 years) after surgery. Surveys were completed by 117 patients (139/196 shoulders, 71% follow-up) at a mean of 5.1 years (range, 1.6-11.2 years) after surgery. Only 15 patients had neither 1 year of office follow-up nor a completed questionnaire. The remaining 154 patients (178/196 shoulders, 91% follow-up) had clinical follow-up with office, mail, or telephone questionnaire at a mean of 4.8 years (range, 1.0-11.2 years) after surgery. This cohort of patients was used to determine rates of surgical revisions, subscapularis tears, dislocations, and other complications.

Radiographic Outcomes

Patients were included in the radiographic analysis if they had a shoulder radiograph at least 1 year after surgery. One hundred nineteen patients (136/196 shoulders, 69% follow-up) had radiographic follow-up at a mean of 3.7 years (range, 1.0-9.4 years) after surgery.

Statistical Analysis

Statistical analysis was performed with Stata Version 10.0. Paired t tests were used to compare preoperative and postoperative numerical data, including ROM and survey scores. We calculated 95% confidence intervals (CIs) and set statistical significance at P < .05. For qualitative measures, the Fisher exact test was used. Survivorship analysis was performed according to the Kaplan-Meier method, with right-censored data for no event or missing data.²⁵

Results

Clinical Analysis of Demographics

In demographics, the clinical and radiographic patient subgroups were similar to each other and to the overall study population (Table 2). Of 196 patients overall, 16 (8%) had a concomitant rotator cuff repair, and 27 (14%) underwent staged bilateral shoulder arthroplasties.

Clinical Analysis of ROM and Survey Scores

Operative shoulder ROM in forward elevation, external rotation at side, external rotation in abduction, and internal rotation all showed statistically significant (P < .001) improvement from before surgery to after surgery. Over 3.7 years, mean (SD) forward elevation improved from 107.3° (34.8°) to 159.0° (29.4°), external rotation at side improved from 20.4° (16.7°) to 49.4° (11.3°), and external rotation in abduction improved from 53.7° (24.3°) to 84.7° (9.1°). Internal rotation improved from a mean (SD) vertebral level of S1 (6.0 levels) to T9 (3.7 levels).

All validated survey scores also showed statistically significant (P < .001) improvement from before surgery to after surgery. Over 5.1 years, mean (SD) SF-36 scores improved from 64.9 (13.4) to 73.6 (17.1), ASES scores improved from 41.1 (22.5) to 82.7 (17.7), SST scores improved from 3.9 (2.8) to 9.7 (2.2), and visual analog scale pain scores improved from 5.6 (3.2) to 1.4 (2.1). Of 139 patients with follow-up, 130 (93.5%) were either satisfied or very satisfied with their TSA, and only 119 (86%) were either satisfied or very satisfied with the nonoperative shoulder.

Clinical Analysis of Postoperative Complications

Of the 178 shoulders evaluated for complications, 3 (1.7%) underwent revision surgery. Mean time to revision was 2.3 years (range, 1.5-3.9 years). Two revisions involved the glenoid component, and the third involved the humerus. In one of the glenoid cases, a 77-year-old woman fell and sustained a fracture at the base of the trabecular metal glenoid pegs; her component was revised to an all-polyethylene component, and she had no further complications. In the other glenoid case, a 73-year-old man’s all-polyethylene component loosened after 2 years and was revised to a trabecular metal implant, which loosened as well and was later converted to a hemiarthroplasty. In the humeral case, a 33-year-old man had his 4-year-old index TSA revised to a cemented stem and had no further complications.

Table 4 compares the clinical and radiographic outcomes of patients who required subscapularis repair, capsular shift, or implant revision with the outcomes of all other study patients, and Figure 3 shows Kaplan-Meier survivorship.

Postoperative Radiographic Analysis

Glenoid Component. At a mean of 3.7 years (minimum, 1 year) after surgery, 86 (63%) of 136 radiographically evaluated shoulders showed no glenoid lucencies; the other 50 (37%) showed ≥1 lucency. Of the 136 shoulders, 33 (24%) had a Lazarus score of 1, 15 (11%) had a score of 2, and only 2 (2%) had a score of 3. None of the shoulders had a score of 4 or 5.

Humeral Component. Of the 136 shoulders, 91 (67%) showed no lucencies in any of the 8 humeral stem zones; the other 45 (33%) showed 1 to 3 lucencies. Thirty (22%) of the 136 shoulders had 1 stem lucency zone, 8 (6%) had 2, and 3 (2%) had 3. None of the shoulders had >3 periprosthetic zones with lucent lines.

Discussion

In this article, we describe a hybrid glenoid TSA component with dual radii of curvature. Its central portion is congruent with the humeral head, and its peripheral portion is noncongruent and larger. The most significant finding of our study is the low rate (1.1%) of glenoid component revision 4.8 years after surgery. This rate is the lowest that has been reported in a study of ≥100 patients. Overall implant survival appeared as an almost flat Kaplan-Meir curve. We attribute this low revision rate to improved biomechanics with the hybrid glenoid design. 

Symptomatic glenoid component loosening is the most common TSA complication.^1,26-28 In a review of 73 Neer TSAs, Cofield7 found glenoid radiolucencies in 71% of patients 3.8 years after surgery. Radiographic evidence of loosening, defined as component migration, or tilt, or a circumferential lucency 1.5 mm thick, was present in another 11% of patients, and 4.1% developed symptomatic loosening that required glenoid revision. In a study with 12.2-year follow-up, Torchia and colleagues³ found rates of 84% for glenoid radiolucencies, 44% for radiographic loosening, and 5.6% for symptomatic loosening that required revision. In a systematic review of studies with follow-up of ≥10 years, Bohsali and colleagues²⁷ found similar lucency and radiographic loosening rates and a 7% glenoid revision rate. These data suggest glenoid radiolucencies may progress to component loosening.

Degree of joint congruence is a key factor in glenoid loosening. Neer’s congruent design increases the contact area with concentric loading and reduces glenohumeral translation, which leads to reduced polyethylene wear and improved joint stability. In extreme arm positions, however, humeral head subluxation results in edge loading and a glenoid rocking-horse effect.^{9-13,17,29-31} Conversely, nonconforming implants allow increased glenohumeral translation without edge loading,¹⁴ though they also reduce the relative glenohumeral contact area and thus transmit more contact stress to the glenoid.^16,17 A hybrid glenoid component with central conforming and peripheral nonconforming zones may reduce the rocking-horse effect while maximizing ROM and joint stability. Wang and colleagues32 studied the biomechanical properties of this glenoid design and found that the addition of a central conforming region did not increase edge loading.

Additional results from our study support the efficacy of a hybrid glenoid component. Patients’ clinical outcomes improved significantly. At 5.1 years after surgery, 93.5% of patients were satisfied or very satisfied with their procedure and reported less satisfaction (86%) with the nonoperative shoulder. Also significant was the reduced number of radiolucencies. At 3.7 years after surgery, the overall percentage of shoulders with ≥1 glenoid radiolucency was 37%, considerably lower than the 82% reported by Cofield7 and the rates in more recent studies.^3,16,33-36 Of the 178 shoulders in our study, 10 (5.6%) had subscapularis tears, and 6 (3.4%) of 178 had these tears surgically repaired. This 3.4% compares favorably with the 5.9% (of 119 patients) found by Miller and colleagues37 28 months after surgery. Of our 178 shoulders, 27 (15.2%) had clinically significant postoperative complications; 18 (10.1%) of the 178 had these complications surgically treated, and 9 (5.1%) had them managed nonoperatively. Bohsali and colleagues²⁷ systematically reviewed 33 TSA studies and found a slightly higher complication rate (16.3%) 5.3 years after surgery. Furthermore, in our study, the 11 patients who underwent revision, capsular shift, or subscapularis repair had final outcomes comparable to those of the rest of our study population.

Our study had several potential weaknesses. First, its minimum clinical and radiographic follow-up was 1 year, whereas most long-term TSA series set a minimum of 2 years. We used 1 year because this was the first clinical study of the hybrid glenoid component design, and we wanted to maximize its sample size by reporting on intermediate-length outcomes. Even so, 93% (166/178) of our clinical patients and 83% (113/136) of our radiographic patients have had ≥2 years of follow-up, and we continue to follow all study patients for long-term outcomes. Another weakness of the study was its lack of a uniform group of patients with all the office, survey, complications, and radiographic data. Our retrospective study design made it difficult to obtain such a group without significantly reducing the sample size, so we divided patients into 4 data groups. A third potential weakness was the study’s variable method for collecting complications data. Rates of complications in the 178 shoulders were calculated from either office evaluation or patient self-report by mail or telephone. This data collection method is subject to recall bias, but mail and telephone contact was needed so the study would capture the large number of patients who had traveled to our institution for their surgery or had since moved away. Fourth, belly-press and lift-off tests were used in part to assess subscapularis function, but recent literature suggests post-TSA subscapularis assessment can be unreliable.³⁸ These tests may be positive in up to two-thirds of patients after 2 years.³⁹ Fifth, the generalizability of our findings to diagnoses such as rheumatoid and posttraumatic arthritis is limited. We had to restrict the study to patients with primary glenohumeral arthritis in order to minimize confounders.

This study’s main strength is its description of the clinical and radiographic outcomes of using a single prosthetic system in operations performed by a single surgeon in a large number of patients. This was the first and largest study evaluating the clinical and radiographic outcomes of this hybrid glenoid implant. Excluding patients with nonprimary arthritis allowed us to minimize potential confounding factors that affect patient outcomes. In conclusion, our study results showed the favorable clinical and radiographic outcomes of TSAs that have a hybrid glenoid component with dual radii of curvature. At a mean of 3.7 years after surgery, 63% of patients had no glenoid lucencies, and, at a mean of 4.8 years, only 1.7% of patients required revision. We continue to follow these patients to obtain long-term results of this innovative prosthesis.

Take-Home Points

• The authors have developed a total shoulder glenoid prosthesis that conforms with the humeral head in its center and is nonconforming on its peripheral edge.
• All clinical survey and range of motion parameters demonstrated statistically significant improvements at final follow-up.
• Only 3 shoulders (1.7%) required revision surgery.
• Eighty-six (63%) of 136 shoulders demonstrated no radiographic evidence of glenoid loosening.
• This is the first and largest study that evaluates the clinical and radiographic outcomes of this hybrid shoulder prosthesis.

Fixation of the glenoid component is the limiting factor in modern total shoulder arthroplasty (TSA). Glenoid loosening, the most common long-term complication, necessitates revision in up to 12% of patients.^1-4 By contrast, humeral component loosening is relatively uncommon, affecting as few as 0.34% of patients.⁵ Multiple long-term studies have found consistently high rates (45%-93%) of radiolucencies around the glenoid component.^3,6,7 Although their clinical significance has been debated, radiolucencies around the glenoid component raise concern about progressive loss of fixation.

Since TSA was introduced in the 1970s, complications with the glenoid component have been addressed with 2 different designs: conforming (congruent) and nonconforming. In a congruent articulation, the radii of curvature of the glenoid and humeral head components are identical, whereas they differ in a nonconforming model. Joint conformity is inversely related to glenohumeral translation.⁸ Neer’s original TSA was made congruent in order to limit translation and maximize the contact area. However, this design results in edge loading and a so-called rocking-horse phenomenon, which may lead to glenoid loosening.^9-13 Surgeons therefore have increasingly turned to nonconforming implants. In the nonconforming design, the radius of curvature of the humeral head is smaller than that of the glenoid. Although this design may reduce edge loading,¹⁴ it allows more translation and reduces the relative contact area of the glenohumeral joint. As a result, more contact stress is transmitted to the glenoid component, leading to polyethylene deformation and wear.^15,16

Dual radii of curvature are designed to augment joint stability without increasing component wear. Biomechanical data have indicated that edge loading is not increased by having a central conforming region added to a nonconforming model.¹⁷ The clinical value of this prosthesis, however, has not been determined. Therefore, we conducted a study to describe the intermediate-term clinical and radiographic outcomes of TSAs that use a novel hybrid glenoid component.

Materials and Methods

This study was approved (protocol AAAD3473) by the Institutional Review Board of Columbia University and was conducted in compliance with Health Insurance Portability and Accountability Act (HIPAA) regulations.

Patient Selection

At Columbia University Medical Center, Dr. Bigliani performed 196 TSAs with a hybrid glenoid component (Bigliani-Flatow; Zimmer Biomet) in 169 patients between September 1998 and November 2007. All patients had received a diagnosis of primary glenohumeral arthritis as defined by Neer.¹⁸ Patients with previous surgery such as rotator cuff repair or subacromial decompression were included in our review, and patients with a nonprimary form of arthritis, such as rheumatoid, posttraumatic, or post-capsulorrhaphy arthritis, were excluded.

Operative Technique

For all surgeries, Dr. Bigliani performed a subscapularis tenotomy with regional anesthesia and a standard deltopectoral approach. A partial anterior capsulectomy was performed to increase the glenoid’s visibility. The inferior labrum was removed with a needle-tip bovie while the axillary nerve was being protected with a metal finger or narrow Darrach retractor. After reaming and trialing, the final glenoid component was cemented into place. Cement was placed only in the peg or keel holes and pressurized twice before final implantation. Of the 196 glenoid components, 168 (86%) were pegged and 28 (14%) keeled; in addition,190 of these components were all-polyethylene, whereas 6 had trabecular-metal backing. All glenoid components incorporated the hybrid design of dual radii of curvature. After the glenoid was cemented, the final humeral component was placed in 30° of retroversion. Whenever posterior wear was found, retroversion was reduced by 5° to 10°. The humeral prosthesis was cemented in cases (104/196, 53%) of poor bone quality or a large canal.

After surgery, the patient’s sling was fitted with an abduction pillow and a swathe, to be worn the first 24 hours, and the arm was passively ranged. Patients typically were discharged on postoperative day 2. Then, for 2 weeks, they followed an assisted passive range of motion (ROM) protocol, with limited external rotation, for promotion of subscapularis healing.

Clinical Outcomes

Dr. Bigliani assessed preoperative ROM in all planes. During initial evaluation, patients completed a questionnaire that consisted of the 36-Item Short Form Health Survey^19,20 (SF-36) and the American Shoulder and Elbow Surgeons²¹ (ASES) and Simple Shoulder Test²² (SST) surveys. Postoperative clinical data were collected from office follow-up visits, survey questionnaires, or both. Postoperative office data included ROM, subscapularis integrity testing (belly-press or lift-off), and any complications. Patients with <1 year of office follow-up were excluded. In addition, the same survey questionnaire that was used before surgery was mailed to all patients after surgery; then, for anyone who did not respond by mail, we attempted contact by telephone. Neer criteria were based on patients’ subjective assessment of each arm on a 3-point Likert scale (1 = very satisfied, 2 = satisfied, 3 = dissatisfied). Patients were also asked about any specific complications or revision operations since their index procedure.

Physical examination and office follow-up data were obtained for 129 patients (148/196 shoulders, 76% follow-up) at a mean of 3.7 years (range 1.0-10.2 years) after surgery. Surveys were completed by 117 patients (139/196 shoulders, 71% follow-up) at a mean of 5.1 years (range, 1.6-11.2 years) after surgery. Only 15 patients had neither 1 year of office follow-up nor a completed questionnaire. The remaining 154 patients (178/196 shoulders, 91% follow-up) had clinical follow-up with office, mail, or telephone questionnaire at a mean of 4.8 years (range, 1.0-11.2 years) after surgery. This cohort of patients was used to determine rates of surgical revisions, subscapularis tears, dislocations, and other complications.

Radiographic Outcomes

Patients were included in the radiographic analysis if they had a shoulder radiograph at least 1 year after surgery. One hundred nineteen patients (136/196 shoulders, 69% follow-up) had radiographic follow-up at a mean of 3.7 years (range, 1.0-9.4 years) after surgery.

Statistical Analysis

Statistical analysis was performed with Stata Version 10.0. Paired t tests were used to compare preoperative and postoperative numerical data, including ROM and survey scores. We calculated 95% confidence intervals (CIs) and set statistical significance at P < .05. For qualitative measures, the Fisher exact test was used. Survivorship analysis was performed according to the Kaplan-Meier method, with right-censored data for no event or missing data.²⁵

Results

Clinical Analysis of Demographics

In demographics, the clinical and radiographic patient subgroups were similar to each other and to the overall study population (Table 2). Of 196 patients overall, 16 (8%) had a concomitant rotator cuff repair, and 27 (14%) underwent staged bilateral shoulder arthroplasties.

Clinical Analysis of ROM and Survey Scores

Operative shoulder ROM in forward elevation, external rotation at side, external rotation in abduction, and internal rotation all showed statistically significant (P < .001) improvement from before surgery to after surgery. Over 3.7 years, mean (SD) forward elevation improved from 107.3° (34.8°) to 159.0° (29.4°), external rotation at side improved from 20.4° (16.7°) to 49.4° (11.3°), and external rotation in abduction improved from 53.7° (24.3°) to 84.7° (9.1°). Internal rotation improved from a mean (SD) vertebral level of S1 (6.0 levels) to T9 (3.7 levels).

All validated survey scores also showed statistically significant (P < .001) improvement from before surgery to after surgery. Over 5.1 years, mean (SD) SF-36 scores improved from 64.9 (13.4) to 73.6 (17.1), ASES scores improved from 41.1 (22.5) to 82.7 (17.7), SST scores improved from 3.9 (2.8) to 9.7 (2.2), and visual analog scale pain scores improved from 5.6 (3.2) to 1.4 (2.1). Of 139 patients with follow-up, 130 (93.5%) were either satisfied or very satisfied with their TSA, and only 119 (86%) were either satisfied or very satisfied with the nonoperative shoulder.

Clinical Analysis of Postoperative Complications

Of the 178 shoulders evaluated for complications, 3 (1.7%) underwent revision surgery. Mean time to revision was 2.3 years (range, 1.5-3.9 years). Two revisions involved the glenoid component, and the third involved the humerus. In one of the glenoid cases, a 77-year-old woman fell and sustained a fracture at the base of the trabecular metal glenoid pegs; her component was revised to an all-polyethylene component, and she had no further complications. In the other glenoid case, a 73-year-old man’s all-polyethylene component loosened after 2 years and was revised to a trabecular metal implant, which loosened as well and was later converted to a hemiarthroplasty. In the humeral case, a 33-year-old man had his 4-year-old index TSA revised to a cemented stem and had no further complications.

Table 4 compares the clinical and radiographic outcomes of patients who required subscapularis repair, capsular shift, or implant revision with the outcomes of all other study patients, and Figure 3 shows Kaplan-Meier survivorship.

Postoperative Radiographic Analysis

Glenoid Component. At a mean of 3.7 years (minimum, 1 year) after surgery, 86 (63%) of 136 radiographically evaluated shoulders showed no glenoid lucencies; the other 50 (37%) showed ≥1 lucency. Of the 136 shoulders, 33 (24%) had a Lazarus score of 1, 15 (11%) had a score of 2, and only 2 (2%) had a score of 3. None of the shoulders had a score of 4 or 5.

Humeral Component. Of the 136 shoulders, 91 (67%) showed no lucencies in any of the 8 humeral stem zones; the other 45 (33%) showed 1 to 3 lucencies. Thirty (22%) of the 136 shoulders had 1 stem lucency zone, 8 (6%) had 2, and 3 (2%) had 3. None of the shoulders had >3 periprosthetic zones with lucent lines.

Discussion

In this article, we describe a hybrid glenoid TSA component with dual radii of curvature. Its central portion is congruent with the humeral head, and its peripheral portion is noncongruent and larger. The most significant finding of our study is the low rate (1.1%) of glenoid component revision 4.8 years after surgery. This rate is the lowest that has been reported in a study of ≥100 patients. Overall implant survival appeared as an almost flat Kaplan-Meir curve. We attribute this low revision rate to improved biomechanics with the hybrid glenoid design. 

Symptomatic glenoid component loosening is the most common TSA complication.^1,26-28 In a review of 73 Neer TSAs, Cofield7 found glenoid radiolucencies in 71% of patients 3.8 years after surgery. Radiographic evidence of loosening, defined as component migration, or tilt, or a circumferential lucency 1.5 mm thick, was present in another 11% of patients, and 4.1% developed symptomatic loosening that required glenoid revision. In a study with 12.2-year follow-up, Torchia and colleagues³ found rates of 84% for glenoid radiolucencies, 44% for radiographic loosening, and 5.6% for symptomatic loosening that required revision. In a systematic review of studies with follow-up of ≥10 years, Bohsali and colleagues²⁷ found similar lucency and radiographic loosening rates and a 7% glenoid revision rate. These data suggest glenoid radiolucencies may progress to component loosening.

Degree of joint congruence is a key factor in glenoid loosening. Neer’s congruent design increases the contact area with concentric loading and reduces glenohumeral translation, which leads to reduced polyethylene wear and improved joint stability. In extreme arm positions, however, humeral head subluxation results in edge loading and a glenoid rocking-horse effect.^{9-13,17,29-31} Conversely, nonconforming implants allow increased glenohumeral translation without edge loading,¹⁴ though they also reduce the relative glenohumeral contact area and thus transmit more contact stress to the glenoid.^16,17 A hybrid glenoid component with central conforming and peripheral nonconforming zones may reduce the rocking-horse effect while maximizing ROM and joint stability. Wang and colleagues32 studied the biomechanical properties of this glenoid design and found that the addition of a central conforming region did not increase edge loading.

Additional results from our study support the efficacy of a hybrid glenoid component. Patients’ clinical outcomes improved significantly. At 5.1 years after surgery, 93.5% of patients were satisfied or very satisfied with their procedure and reported less satisfaction (86%) with the nonoperative shoulder. Also significant was the reduced number of radiolucencies. At 3.7 years after surgery, the overall percentage of shoulders with ≥1 glenoid radiolucency was 37%, considerably lower than the 82% reported by Cofield7 and the rates in more recent studies.^3,16,33-36 Of the 178 shoulders in our study, 10 (5.6%) had subscapularis tears, and 6 (3.4%) of 178 had these tears surgically repaired. This 3.4% compares favorably with the 5.9% (of 119 patients) found by Miller and colleagues37 28 months after surgery. Of our 178 shoulders, 27 (15.2%) had clinically significant postoperative complications; 18 (10.1%) of the 178 had these complications surgically treated, and 9 (5.1%) had them managed nonoperatively. Bohsali and colleagues²⁷ systematically reviewed 33 TSA studies and found a slightly higher complication rate (16.3%) 5.3 years after surgery. Furthermore, in our study, the 11 patients who underwent revision, capsular shift, or subscapularis repair had final outcomes comparable to those of the rest of our study population.

Our study had several potential weaknesses. First, its minimum clinical and radiographic follow-up was 1 year, whereas most long-term TSA series set a minimum of 2 years. We used 1 year because this was the first clinical study of the hybrid glenoid component design, and we wanted to maximize its sample size by reporting on intermediate-length outcomes. Even so, 93% (166/178) of our clinical patients and 83% (113/136) of our radiographic patients have had ≥2 years of follow-up, and we continue to follow all study patients for long-term outcomes. Another weakness of the study was its lack of a uniform group of patients with all the office, survey, complications, and radiographic data. Our retrospective study design made it difficult to obtain such a group without significantly reducing the sample size, so we divided patients into 4 data groups. A third potential weakness was the study’s variable method for collecting complications data. Rates of complications in the 178 shoulders were calculated from either office evaluation or patient self-report by mail or telephone. This data collection method is subject to recall bias, but mail and telephone contact was needed so the study would capture the large number of patients who had traveled to our institution for their surgery or had since moved away. Fourth, belly-press and lift-off tests were used in part to assess subscapularis function, but recent literature suggests post-TSA subscapularis assessment can be unreliable.³⁸ These tests may be positive in up to two-thirds of patients after 2 years.³⁹ Fifth, the generalizability of our findings to diagnoses such as rheumatoid and posttraumatic arthritis is limited. We had to restrict the study to patients with primary glenohumeral arthritis in order to minimize confounders.

This study’s main strength is its description of the clinical and radiographic outcomes of using a single prosthetic system in operations performed by a single surgeon in a large number of patients. This was the first and largest study evaluating the clinical and radiographic outcomes of this hybrid glenoid implant. Excluding patients with nonprimary arthritis allowed us to minimize potential confounding factors that affect patient outcomes. In conclusion, our study results showed the favorable clinical and radiographic outcomes of TSAs that have a hybrid glenoid component with dual radii of curvature. At a mean of 3.7 years after surgery, 63% of patients had no glenoid lucencies, and, at a mean of 4.8 years, only 1.7% of patients required revision. We continue to follow these patients to obtain long-term results of this innovative prosthesis.

Take-Home Points

• Guidelines regarding glenoid component size selection for primary TSA are lacking.
• Intraoperative in situ glenoid sizing may not be ideal.
• 3-D digital models may be utilized for preoperative templating of glenoid component size in primary TSA.
• 3-D templating that allows for superior-inferior, anterior-posterior, and rotational translation can lead to consistent and reproducible templating of glenoid component size.
• 3-D templating may reduce the risks of implant overhang, peg penetration, and decreased stability ratio.

In 1974, Neer¹ introduced the shoulder prosthesis. In 1982, Neer and colleagues² found significant improvement in shoulder pain and function in patients with glenohumeral osteoarthritis treated with the Neer prosthesis. Since then, use of total shoulder arthroplasty (TSA) has increased. Between 1993 and 2007, TSA use increased 319% in the United States.³ Long-term outcomes studies have found implant survivorship ranging from 87% to 93% at 10 to 15 years.⁴

Although TSA is a successful procedure, glenoid component failure is the most common complication.^5-10 Outcomes of revision surgery for glenoid instability are inferior to those of primary TSA.¹¹ Recent research findings highlight the effect of glenoid size on TSA complications.¹² A larger glenoid component increases the stability ratio (peak subluxation force divided by compression load).¹² However, insufficient glenoid bone stock, small glenoid diameter, and inability to fit a properly sized reamer owing to soft-tissue constraints may lead surgeons to choose a smaller glenoid component in order to avoid peg penetration, overhang, and soft-tissue damage, respectively. Therefore, preoperative templating of glenoid size is a potential strategy for minimizing complications.

Templating is performed for proximal humeral components, but glenoid sizing typically is deferred to intraoperative in situ sizing with implant-specific targeting guides. This glenoid sizing practice arose out of a lack of standard digital glenoid templates and difficulty in selecting glenoid size based on plain radiographs and/or 2-dimensional (2-D) computed tomography (CT) scans. However, targeting devices are sporadically used during surgery, and intraoperative glenoid vault dimension estimates derived from visualization and palpation are often inaccurate. Often, rather than directly assess glenoid morphology, surgeons infer glenoid size from the size and sex of patients.¹³

Three-dimensional (3-D) CT can be used to accurately assess glenoid version, bone loss, and implant fit.^14-19 We conducted a study to determine if 3-D digital imaging can be consistently and reproducibly used for preoperative templating of glenoid component size and to determine if glenoid sizes derived from templating correlate with the sizes of subsequently implanted glenoids.

Materials and Methods

This retrospective study was conducted at the Center for Shoulder, Elbow, and Sports Medicine at Columbia University Medical Center in New York City and was approved by our Institutional Review Board. Included in the study were all patients who underwent primary TSA for primary glenohumeral osteoarthritis over a 12-month period. Patients were required to have preoperative CT performed according to our study protocol. The CT protocol consisted of 0.5-mm axial cuts of the entire scapula and 3-D reconstruction of the scapula, glenoid, glenohumeral articulation, and proximal humerus. Patients were excluded from the study for primary TSA for a secondary cause of glenohumeral osteoarthritis, inflammatory arthritis, connective tissue disease, prior contralateral TSA, and prior ipsilateral scapula, glenoid, and proximal humerus surgery. Ultimately, 24 patients were included in the study.

CT data were formatted for preoperative templating. The CT images of each patient’s scapula were uploaded into Materialise Interactive Medical Image Control System (Mimics) software. Mimics allows 3-D image rendering and editing from various imaging modalities and formats. The software was used to create the 3-D scapula models for templating. Prior studies have validated the anatomical precision of 3-D models created with Mimics.²⁰

Mimics was also used to digitize in 3-D the glenoid components from the Bigliani-Flatow Shoulder System (Zimmer Biomet). Glenoid components of 3 different sizes (40 mm, 46 mm, 52 mm) were used. (The Bigliani glenoid component was digitized, as this implant system was used for primary TSA in all 24 patients.) Each glenoid component was traced in 3-D with a Gage 2000 coordinate-measuring machine (Brown & Sharpe) and was processed with custom software. The custom software, cited in previous work by our group,¹⁷ created the same coordinate system for each scapula based on anatomical reference points. These digitized 3-D images of glenoid components were uploaded with the digitized 3-D scapulae derived from patients’ CT scans to the Magics software. Magics allows for manipulation and interaction of multiple 3-D models by creating electronic stereolithography files that provide 3-D surface geometry.

Three fellowship-trained shoulder surgeons and 4 shoulder fellows templated the most appropriately sized glenoid component for each of the 24 patients. At the time of templating, the surgeon was blinded to the size of the glenoid implant used in the surgery. In Magics, each scapula was positioned in 3-D similar to how it would appear with the patient in the beach-chair position during surgery. In both study arms, surgeons selected the largest component that maximized the area of contact while avoiding peg penetration of the glenoid vault or component overhang. In addition, surgeons were instructed to correct glenoid version to as near neutral as possible with component positioning but were not permitted to remove glenoid bone stock to correct deformity. All surgeons based placement of the glenoid component on the patient’s actual bone stock and not on osteophytes, which are readily appreciable on 3-D CT.

In study arm 1, the 3-D view of the glenoid was restricted to the initial view in the beach-chair position. The surgeon then manipulated the 3-D glenoid component template across a single 2-D plane, either the superior-inferior plane or the anterior-posterior plane, over the surface of the 3-D glenoid (Figure 1).

In study arm 2, surgeons were permitted to rotate the 3-D glenoid template and scapula in any manner (Figure 2).

Interobserver agreement was determined by comparing prosthetic glenoid component size selection among all study surgeons, and intraobserver agreement was determined by comparing glenoid size selection during 2 sessions separated by at least 3 weeks.

After each trial, the order of patients’ scapula images was randomly rearranged to reduce recall bias. Kappa (κ) coefficients were calculated for interobserver and intraobserver agreement. Kappas ranged from −1.0 (least agreement) to +1.0 (complete agreement). A κ of 0 indicated an observer selection was equivalent to random chance. The level of agreement was categorized according to κ using a system described by Landis and Koch²¹ (Table 1).

Results

The group of 24 patients consisted of 15 men and 9 women. Mean age was 70.3 years (range, 56-88 years). Primary TSA was performed in 14 right shoulders and 10 left shoulders. Of the 24 patients, 20 (83%) had a 46-mm glenoid component implanted, 3 male patients had a 52-mm glenoid component implanted, and 1 female patient had a 40-mm glenoid component implanted.

Study Arm 1: Glenoid Templating Based on 2 df 

In study arm 1, overall intraobserver agreement was substantial, as defined in the statistical literature.²¹ Among all surgeons who participated, intraobserver agreeement was 0.76 (substantial), 0.60 (substantial), and 0.58 (moderate) for the 40-mm, 46-mm, and 52-mm glenoid components, respectively (overall κ = 0.67, substantial agreement). Trial 1 interobserver agreement was 0.56 (moderate) (P < .001), 0.25 (fair) (P < .001), and 0.21 (fair) (P < .001) for the 40-mm, 46-mm, and 52-mm glenoid components, respectively (overall κ = 0.36, fair agreement) (P < .001), and trial 2 interobserver agreement was 0.58 (moderate) (P < .001), 0.18 (poor) (P = .003), and 0.24 (fair) (P <.001) for the 40-mm, 46-mm, and 52-mm glenoid components, respectively (overall κ = 0.32, fair agreement) (P < .001). In study arm 1, therefore, trials 1 and 2 both showed fair interobserver agreement.

Study Arm 2: Glenoid Templating Based on 6 df

In study arm 2, a mean correlation of 0.42 (moderate agreement) was found between glenoid component size in 3-D templating and the glenoid component size ultimately selected during surgery (Table 3).

In study arm 2, overall intraobserver agreement was moderate. Among all surgeons who participated, intraobserver agreement was 0.80 (excellent), 0.43 (moderate), and 0.47 (moderate) for the 40-mm, 46-mm, and 52-mm glenoid components, respectively (overall κ = 0.58, moderate agreement). Trial 1 interobserver agreement was 0.75 (substantial) (P < .001), 0.39 (fair) (P < .001), and 0.50 (moderate) (P < .001) for the 40-mm, 46-mm, and 52-mm glenoid components, respectively (overall κ = 0.54, moderate agreement) (P < .001), and trial 2 interobserver agreement was 0.66 (substantial) (P < .001), 0.28 (fair) (P = .003), and 0.40 (moderate) (P < .001) for the 40-mm, 46-mm, and 52-mm glenoid components, respectively (overall κ = 0.43, moderate agreement) (P < .001). 

Discussion

Our results showed that 3-D glenoid templating had reproducible intraobserver and interobserver agreement. Overall intraobserver agreement was substantial (κ = 0.67) for study arm 1 and moderate (κ = 0.58) for study arm 2. Interobserver agreement was fair for trials 1 and 2 (κ = 0.36 and 0.32) in arm 1 and moderate for trials 1 and 2 (κ = 0.54 and 0.43) in arm 2.

Intraobserver and interobserver agreement values, particularly in study arm 2, which incorporated rotation (6 df), are consistent with values in commonly used classification systems, such as the Neer system for proximal humerus fractures, the Frykman system for distal radius fractures, and the King system for adolescent idiopathic scoliosis.^22-30 Sidor and colleagues²⁷ found overall interobserver agreement of 0.50 and overall intraobserver agreement of 0.66 for the Neer system, and Illarramendi and colleagues²⁴ found overall interobserver agreement of 0.43 and overall intraobserver agreement of 0.61 for the Frykman system.

In study arm 2, overall interobserver and intraobserver agreement was moderate. A higher level of surgeon agreement is unlikely given the lack of well-defined parameters for determining glenoid component size. Therefore, glenoid size selection is largely a matter of surgeon preference. More research is needed to establish concrete guidelines for glenoid component size selection. Once guidelines are adopted, interobserver agreement in templating may increase.

In both study arms, the component that surgeons selected during templating tended to be smaller than the component they selected during surgery. In study arm 1, 32% of patients had a smaller component selected based on computer modeling, and 7% had a larger component selected. In study arm 2, the difference was narrower: 27% of patients had a smaller component selected during templating, and 16% had a larger component selected. A statistically significant difference (P < .001) in templated and implanted component sizes was found between men and women: Templated glenoid components were smaller than implanted components in 53% of women and larger than implanted components in 33% of men. Differences between templated and implanted components may be attributable to visualization differences. During templating, the entire glenoid can be visualized and the slightest peg penetration or component overhang detected; in contrast, during surgery, anatomical constraints preclude such a comprehensive assessment.

Differences in agreement between templated and implanted glenoid components suggest that the size of implanted components may not be ideal. In this study, the distribution of the templated glenoid sizes was much wider than that of the implanted glenoid sizes. During templating, each glenoid component can be definitively visualized and assessed for possible peg penetration and overhang. Visualization allows surgeons to base glenoid size selection solely on glenoid morphology, as opposed to factors such as patient sex and height. In addition, interobserver and intraobserver agreement values for the 40-mm glenoid component were considerably higher than those for components of other sizes, indicating that the 40-mm component was consistently and reproducibly selected for the same patients. Hence, templating may particularly help prevent peg penetration and component overhang for patients with a smaller diameter glenoid.

More research on 3-D templating is warranted given the results of this study and other studies.^12,17,31 Scalise and colleagues³¹ found that, in TSA planning, surgeons’ use of 2-D (vs 3-D) imaging led them to overestimate glenoid component sizes (P = .006). In our study, the glenoid size selected during 3-D templating was, in many cases, smaller than the size selected during surgery. In order to avoid peg penetration and glenoid overhang, anecdotal guidelines commonly used in glenoid size selection, likely was the driving force in selecting smaller glenoid components during templating. Although anterior, superior, and inferior glenoid overhang typically can be assessed during surgery, posterior overhang is more difficult to evaluate. Three-dimensional modeling allows surgeons to determine optimal glenoid component size and position. In addition, intraoperative evaluation of glenoid component peg penetration is challenging, and peg penetration becomes evident only after it has occurred. During templating, however, surgeons were able to easily assess for peg penetration, and smaller glenoid components were selected.

A limitation of this study is that intraoperative glenoid version correction or peg containment was not quantified. More research is needed on the relationship between glenoid size selection and component overhang and peg penetration. Another limitation was use of only 1 TSA system (with 3 glenoid sizes, all with inline pegs); reliability of 3-D templating was not evaluated across different component designs. Last, given the absence of guidelines for glenoid component size selection, there was surgeon bias in preoperative templating and in intraoperative selection of glenoid size. Surgeons had differing opinions on the importance of maximizing the contact area of the component and correcting glenoid deformity and version.

Our study results showed that preoperative 3-D templating that allows for superior-inferior, anterior-posterior, and rotational translation was consistent and reproducible in determining glenoid component size, and use of this templating may reduce the risks of implant overhang, peg penetration, and decreased stability ratio. These results highlight the possibility that glenoid component sizes selected during surgery may not be ideal. More research is needed to determine if intraoperative glenoid size selection leads to adequate version correction and peg containment. The present study supports use of 3-D templating in primary TSA planning.

Take-Home Points

• Guidelines regarding glenoid component size selection for primary TSA are lacking.
• Intraoperative in situ glenoid sizing may not be ideal.
• 3-D digital models may be utilized for preoperative templating of glenoid component size in primary TSA.
• 3-D templating that allows for superior-inferior, anterior-posterior, and rotational translation can lead to consistent and reproducible templating of glenoid component size.
• 3-D templating may reduce the risks of implant overhang, peg penetration, and decreased stability ratio.

In 1974, Neer¹ introduced the shoulder prosthesis. In 1982, Neer and colleagues² found significant improvement in shoulder pain and function in patients with glenohumeral osteoarthritis treated with the Neer prosthesis. Since then, use of total shoulder arthroplasty (TSA) has increased. Between 1993 and 2007, TSA use increased 319% in the United States.³ Long-term outcomes studies have found implant survivorship ranging from 87% to 93% at 10 to 15 years.⁴

Although TSA is a successful procedure, glenoid component failure is the most common complication.^5-10 Outcomes of revision surgery for glenoid instability are inferior to those of primary TSA.¹¹ Recent research findings highlight the effect of glenoid size on TSA complications.¹² A larger glenoid component increases the stability ratio (peak subluxation force divided by compression load).¹² However, insufficient glenoid bone stock, small glenoid diameter, and inability to fit a properly sized reamer owing to soft-tissue constraints may lead surgeons to choose a smaller glenoid component in order to avoid peg penetration, overhang, and soft-tissue damage, respectively. Therefore, preoperative templating of glenoid size is a potential strategy for minimizing complications.

Templating is performed for proximal humeral components, but glenoid sizing typically is deferred to intraoperative in situ sizing with implant-specific targeting guides. This glenoid sizing practice arose out of a lack of standard digital glenoid templates and difficulty in selecting glenoid size based on plain radiographs and/or 2-dimensional (2-D) computed tomography (CT) scans. However, targeting devices are sporadically used during surgery, and intraoperative glenoid vault dimension estimates derived from visualization and palpation are often inaccurate. Often, rather than directly assess glenoid morphology, surgeons infer glenoid size from the size and sex of patients.¹³

Three-dimensional (3-D) CT can be used to accurately assess glenoid version, bone loss, and implant fit.^14-19 We conducted a study to determine if 3-D digital imaging can be consistently and reproducibly used for preoperative templating of glenoid component size and to determine if glenoid sizes derived from templating correlate with the sizes of subsequently implanted glenoids.

Materials and Methods

This retrospective study was conducted at the Center for Shoulder, Elbow, and Sports Medicine at Columbia University Medical Center in New York City and was approved by our Institutional Review Board. Included in the study were all patients who underwent primary TSA for primary glenohumeral osteoarthritis over a 12-month period. Patients were required to have preoperative CT performed according to our study protocol. The CT protocol consisted of 0.5-mm axial cuts of the entire scapula and 3-D reconstruction of the scapula, glenoid, glenohumeral articulation, and proximal humerus. Patients were excluded from the study for primary TSA for a secondary cause of glenohumeral osteoarthritis, inflammatory arthritis, connective tissue disease, prior contralateral TSA, and prior ipsilateral scapula, glenoid, and proximal humerus surgery. Ultimately, 24 patients were included in the study.

CT data were formatted for preoperative templating. The CT images of each patient’s scapula were uploaded into Materialise Interactive Medical Image Control System (Mimics) software. Mimics allows 3-D image rendering and editing from various imaging modalities and formats. The software was used to create the 3-D scapula models for templating. Prior studies have validated the anatomical precision of 3-D models created with Mimics.²⁰

Mimics was also used to digitize in 3-D the glenoid components from the Bigliani-Flatow Shoulder System (Zimmer Biomet). Glenoid components of 3 different sizes (40 mm, 46 mm, 52 mm) were used. (The Bigliani glenoid component was digitized, as this implant system was used for primary TSA in all 24 patients.) Each glenoid component was traced in 3-D with a Gage 2000 coordinate-measuring machine (Brown & Sharpe) and was processed with custom software. The custom software, cited in previous work by our group,¹⁷ created the same coordinate system for each scapula based on anatomical reference points. These digitized 3-D images of glenoid components were uploaded with the digitized 3-D scapulae derived from patients’ CT scans to the Magics software. Magics allows for manipulation and interaction of multiple 3-D models by creating electronic stereolithography files that provide 3-D surface geometry.

Three fellowship-trained shoulder surgeons and 4 shoulder fellows templated the most appropriately sized glenoid component for each of the 24 patients. At the time of templating, the surgeon was blinded to the size of the glenoid implant used in the surgery. In Magics, each scapula was positioned in 3-D similar to how it would appear with the patient in the beach-chair position during surgery. In both study arms, surgeons selected the largest component that maximized the area of contact while avoiding peg penetration of the glenoid vault or component overhang. In addition, surgeons were instructed to correct glenoid version to as near neutral as possible with component positioning but were not permitted to remove glenoid bone stock to correct deformity. All surgeons based placement of the glenoid component on the patient’s actual bone stock and not on osteophytes, which are readily appreciable on 3-D CT.

In study arm 1, the 3-D view of the glenoid was restricted to the initial view in the beach-chair position. The surgeon then manipulated the 3-D glenoid component template across a single 2-D plane, either the superior-inferior plane or the anterior-posterior plane, over the surface of the 3-D glenoid (Figure 1).

In study arm 2, surgeons were permitted to rotate the 3-D glenoid template and scapula in any manner (Figure 2).

Interobserver agreement was determined by comparing prosthetic glenoid component size selection among all study surgeons, and intraobserver agreement was determined by comparing glenoid size selection during 2 sessions separated by at least 3 weeks.

After each trial, the order of patients’ scapula images was randomly rearranged to reduce recall bias. Kappa (κ) coefficients were calculated for interobserver and intraobserver agreement. Kappas ranged from −1.0 (least agreement) to +1.0 (complete agreement). A κ of 0 indicated an observer selection was equivalent to random chance. The level of agreement was categorized according to κ using a system described by Landis and Koch²¹ (Table 1).

Results

The group of 24 patients consisted of 15 men and 9 women. Mean age was 70.3 years (range, 56-88 years). Primary TSA was performed in 14 right shoulders and 10 left shoulders. Of the 24 patients, 20 (83%) had a 46-mm glenoid component implanted, 3 male patients had a 52-mm glenoid component implanted, and 1 female patient had a 40-mm glenoid component implanted.

Study Arm 1: Glenoid Templating Based on 2 df 

In study arm 1, overall intraobserver agreement was substantial, as defined in the statistical literature.²¹ Among all surgeons who participated, intraobserver agreeement was 0.76 (substantial), 0.60 (substantial), and 0.58 (moderate) for the 40-mm, 46-mm, and 52-mm glenoid components, respectively (overall κ = 0.67, substantial agreement). Trial 1 interobserver agreement was 0.56 (moderate) (P < .001), 0.25 (fair) (P < .001), and 0.21 (fair) (P < .001) for the 40-mm, 46-mm, and 52-mm glenoid components, respectively (overall κ = 0.36, fair agreement) (P < .001), and trial 2 interobserver agreement was 0.58 (moderate) (P < .001), 0.18 (poor) (P = .003), and 0.24 (fair) (P <.001) for the 40-mm, 46-mm, and 52-mm glenoid components, respectively (overall κ = 0.32, fair agreement) (P < .001). In study arm 1, therefore, trials 1 and 2 both showed fair interobserver agreement.

Study Arm 2: Glenoid Templating Based on 6 df

In study arm 2, a mean correlation of 0.42 (moderate agreement) was found between glenoid component size in 3-D templating and the glenoid component size ultimately selected during surgery (Table 3).

In study arm 2, overall intraobserver agreement was moderate. Among all surgeons who participated, intraobserver agreement was 0.80 (excellent), 0.43 (moderate), and 0.47 (moderate) for the 40-mm, 46-mm, and 52-mm glenoid components, respectively (overall κ = 0.58, moderate agreement). Trial 1 interobserver agreement was 0.75 (substantial) (P < .001), 0.39 (fair) (P < .001), and 0.50 (moderate) (P < .001) for the 40-mm, 46-mm, and 52-mm glenoid components, respectively (overall κ = 0.54, moderate agreement) (P < .001), and trial 2 interobserver agreement was 0.66 (substantial) (P < .001), 0.28 (fair) (P = .003), and 0.40 (moderate) (P < .001) for the 40-mm, 46-mm, and 52-mm glenoid components, respectively (overall κ = 0.43, moderate agreement) (P < .001). 

Discussion

Our results showed that 3-D glenoid templating had reproducible intraobserver and interobserver agreement. Overall intraobserver agreement was substantial (κ = 0.67) for study arm 1 and moderate (κ = 0.58) for study arm 2. Interobserver agreement was fair for trials 1 and 2 (κ = 0.36 and 0.32) in arm 1 and moderate for trials 1 and 2 (κ = 0.54 and 0.43) in arm 2.

Intraobserver and interobserver agreement values, particularly in study arm 2, which incorporated rotation (6 df), are consistent with values in commonly used classification systems, such as the Neer system for proximal humerus fractures, the Frykman system for distal radius fractures, and the King system for adolescent idiopathic scoliosis.^22-30 Sidor and colleagues²⁷ found overall interobserver agreement of 0.50 and overall intraobserver agreement of 0.66 for the Neer system, and Illarramendi and colleagues²⁴ found overall interobserver agreement of 0.43 and overall intraobserver agreement of 0.61 for the Frykman system.

In study arm 2, overall interobserver and intraobserver agreement was moderate. A higher level of surgeon agreement is unlikely given the lack of well-defined parameters for determining glenoid component size. Therefore, glenoid size selection is largely a matter of surgeon preference. More research is needed to establish concrete guidelines for glenoid component size selection. Once guidelines are adopted, interobserver agreement in templating may increase.

In both study arms, the component that surgeons selected during templating tended to be smaller than the component they selected during surgery. In study arm 1, 32% of patients had a smaller component selected based on computer modeling, and 7% had a larger component selected. In study arm 2, the difference was narrower: 27% of patients had a smaller component selected during templating, and 16% had a larger component selected. A statistically significant difference (P < .001) in templated and implanted component sizes was found between men and women: Templated glenoid components were smaller than implanted components in 53% of women and larger than implanted components in 33% of men. Differences between templated and implanted components may be attributable to visualization differences. During templating, the entire glenoid can be visualized and the slightest peg penetration or component overhang detected; in contrast, during surgery, anatomical constraints preclude such a comprehensive assessment.

Differences in agreement between templated and implanted glenoid components suggest that the size of implanted components may not be ideal. In this study, the distribution of the templated glenoid sizes was much wider than that of the implanted glenoid sizes. During templating, each glenoid component can be definitively visualized and assessed for possible peg penetration and overhang. Visualization allows surgeons to base glenoid size selection solely on glenoid morphology, as opposed to factors such as patient sex and height. In addition, interobserver and intraobserver agreement values for the 40-mm glenoid component were considerably higher than those for components of other sizes, indicating that the 40-mm component was consistently and reproducibly selected for the same patients. Hence, templating may particularly help prevent peg penetration and component overhang for patients with a smaller diameter glenoid.

More research on 3-D templating is warranted given the results of this study and other studies.^12,17,31 Scalise and colleagues³¹ found that, in TSA planning, surgeons’ use of 2-D (vs 3-D) imaging led them to overestimate glenoid component sizes (P = .006). In our study, the glenoid size selected during 3-D templating was, in many cases, smaller than the size selected during surgery. In order to avoid peg penetration and glenoid overhang, anecdotal guidelines commonly used in glenoid size selection, likely was the driving force in selecting smaller glenoid components during templating. Although anterior, superior, and inferior glenoid overhang typically can be assessed during surgery, posterior overhang is more difficult to evaluate. Three-dimensional modeling allows surgeons to determine optimal glenoid component size and position. In addition, intraoperative evaluation of glenoid component peg penetration is challenging, and peg penetration becomes evident only after it has occurred. During templating, however, surgeons were able to easily assess for peg penetration, and smaller glenoid components were selected.

A limitation of this study is that intraoperative glenoid version correction or peg containment was not quantified. More research is needed on the relationship between glenoid size selection and component overhang and peg penetration. Another limitation was use of only 1 TSA system (with 3 glenoid sizes, all with inline pegs); reliability of 3-D templating was not evaluated across different component designs. Last, given the absence of guidelines for glenoid component size selection, there was surgeon bias in preoperative templating and in intraoperative selection of glenoid size. Surgeons had differing opinions on the importance of maximizing the contact area of the component and correcting glenoid deformity and version.

Our study results showed that preoperative 3-D templating that allows for superior-inferior, anterior-posterior, and rotational translation was consistent and reproducible in determining glenoid component size, and use of this templating may reduce the risks of implant overhang, peg penetration, and decreased stability ratio. These results highlight the possibility that glenoid component sizes selected during surgery may not be ideal. More research is needed to determine if intraoperative glenoid size selection leads to adequate version correction and peg containment. The present study supports use of 3-D templating in primary TSA planning.

Take-Home Points

• Guidelines regarding glenoid component size selection for primary TSA are lacking.
• Intraoperative in situ glenoid sizing may not be ideal.
• 3-D digital models may be utilized for preoperative templating of glenoid component size in primary TSA.
• 3-D templating that allows for superior-inferior, anterior-posterior, and rotational translation can lead to consistent and reproducible templating of glenoid component size.
• 3-D templating may reduce the risks of implant overhang, peg penetration, and decreased stability ratio.

In 1974, Neer¹ introduced the shoulder prosthesis. In 1982, Neer and colleagues² found significant improvement in shoulder pain and function in patients with glenohumeral osteoarthritis treated with the Neer prosthesis. Since then, use of total shoulder arthroplasty (TSA) has increased. Between 1993 and 2007, TSA use increased 319% in the United States.³ Long-term outcomes studies have found implant survivorship ranging from 87% to 93% at 10 to 15 years.⁴

Although TSA is a successful procedure, glenoid component failure is the most common complication.^5-10 Outcomes of revision surgery for glenoid instability are inferior to those of primary TSA.¹¹ Recent research findings highlight the effect of glenoid size on TSA complications.¹² A larger glenoid component increases the stability ratio (peak subluxation force divided by compression load).¹² However, insufficient glenoid bone stock, small glenoid diameter, and inability to fit a properly sized reamer owing to soft-tissue constraints may lead surgeons to choose a smaller glenoid component in order to avoid peg penetration, overhang, and soft-tissue damage, respectively. Therefore, preoperative templating of glenoid size is a potential strategy for minimizing complications.

Templating is performed for proximal humeral components, but glenoid sizing typically is deferred to intraoperative in situ sizing with implant-specific targeting guides. This glenoid sizing practice arose out of a lack of standard digital glenoid templates and difficulty in selecting glenoid size based on plain radiographs and/or 2-dimensional (2-D) computed tomography (CT) scans. However, targeting devices are sporadically used during surgery, and intraoperative glenoid vault dimension estimates derived from visualization and palpation are often inaccurate. Often, rather than directly assess glenoid morphology, surgeons infer glenoid size from the size and sex of patients.¹³

Three-dimensional (3-D) CT can be used to accurately assess glenoid version, bone loss, and implant fit.^14-19 We conducted a study to determine if 3-D digital imaging can be consistently and reproducibly used for preoperative templating of glenoid component size and to determine if glenoid sizes derived from templating correlate with the sizes of subsequently implanted glenoids.

Materials and Methods

This retrospective study was conducted at the Center for Shoulder, Elbow, and Sports Medicine at Columbia University Medical Center in New York City and was approved by our Institutional Review Board. Included in the study were all patients who underwent primary TSA for primary glenohumeral osteoarthritis over a 12-month period. Patients were required to have preoperative CT performed according to our study protocol. The CT protocol consisted of 0.5-mm axial cuts of the entire scapula and 3-D reconstruction of the scapula, glenoid, glenohumeral articulation, and proximal humerus. Patients were excluded from the study for primary TSA for a secondary cause of glenohumeral osteoarthritis, inflammatory arthritis, connective tissue disease, prior contralateral TSA, and prior ipsilateral scapula, glenoid, and proximal humerus surgery. Ultimately, 24 patients were included in the study.

CT data were formatted for preoperative templating. The CT images of each patient’s scapula were uploaded into Materialise Interactive Medical Image Control System (Mimics) software. Mimics allows 3-D image rendering and editing from various imaging modalities and formats. The software was used to create the 3-D scapula models for templating. Prior studies have validated the anatomical precision of 3-D models created with Mimics.²⁰

Mimics was also used to digitize in 3-D the glenoid components from the Bigliani-Flatow Shoulder System (Zimmer Biomet). Glenoid components of 3 different sizes (40 mm, 46 mm, 52 mm) were used. (The Bigliani glenoid component was digitized, as this implant system was used for primary TSA in all 24 patients.) Each glenoid component was traced in 3-D with a Gage 2000 coordinate-measuring machine (Brown & Sharpe) and was processed with custom software. The custom software, cited in previous work by our group,¹⁷ created the same coordinate system for each scapula based on anatomical reference points. These digitized 3-D images of glenoid components were uploaded with the digitized 3-D scapulae derived from patients’ CT scans to the Magics software. Magics allows for manipulation and interaction of multiple 3-D models by creating electronic stereolithography files that provide 3-D surface geometry.

Three fellowship-trained shoulder surgeons and 4 shoulder fellows templated the most appropriately sized glenoid component for each of the 24 patients. At the time of templating, the surgeon was blinded to the size of the glenoid implant used in the surgery. In Magics, each scapula was positioned in 3-D similar to how it would appear with the patient in the beach-chair position during surgery. In both study arms, surgeons selected the largest component that maximized the area of contact while avoiding peg penetration of the glenoid vault or component overhang. In addition, surgeons were instructed to correct glenoid version to as near neutral as possible with component positioning but were not permitted to remove glenoid bone stock to correct deformity. All surgeons based placement of the glenoid component on the patient’s actual bone stock and not on osteophytes, which are readily appreciable on 3-D CT.

In study arm 1, the 3-D view of the glenoid was restricted to the initial view in the beach-chair position. The surgeon then manipulated the 3-D glenoid component template across a single 2-D plane, either the superior-inferior plane or the anterior-posterior plane, over the surface of the 3-D glenoid (Figure 1).

In study arm 2, surgeons were permitted to rotate the 3-D glenoid template and scapula in any manner (Figure 2).

Interobserver agreement was determined by comparing prosthetic glenoid component size selection among all study surgeons, and intraobserver agreement was determined by comparing glenoid size selection during 2 sessions separated by at least 3 weeks.

After each trial, the order of patients’ scapula images was randomly rearranged to reduce recall bias. Kappa (κ) coefficients were calculated for interobserver and intraobserver agreement. Kappas ranged from −1.0 (least agreement) to +1.0 (complete agreement). A κ of 0 indicated an observer selection was equivalent to random chance. The level of agreement was categorized according to κ using a system described by Landis and Koch²¹ (Table 1).

Results

The group of 24 patients consisted of 15 men and 9 women. Mean age was 70.3 years (range, 56-88 years). Primary TSA was performed in 14 right shoulders and 10 left shoulders. Of the 24 patients, 20 (83%) had a 46-mm glenoid component implanted, 3 male patients had a 52-mm glenoid component implanted, and 1 female patient had a 40-mm glenoid component implanted.

Study Arm 1: Glenoid Templating Based on 2 df 

In study arm 1, overall intraobserver agreement was substantial, as defined in the statistical literature.²¹ Among all surgeons who participated, intraobserver agreeement was 0.76 (substantial), 0.60 (substantial), and 0.58 (moderate) for the 40-mm, 46-mm, and 52-mm glenoid components, respectively (overall κ = 0.67, substantial agreement). Trial 1 interobserver agreement was 0.56 (moderate) (P < .001), 0.25 (fair) (P < .001), and 0.21 (fair) (P < .001) for the 40-mm, 46-mm, and 52-mm glenoid components, respectively (overall κ = 0.36, fair agreement) (P < .001), and trial 2 interobserver agreement was 0.58 (moderate) (P < .001), 0.18 (poor) (P = .003), and 0.24 (fair) (P <.001) for the 40-mm, 46-mm, and 52-mm glenoid components, respectively (overall κ = 0.32, fair agreement) (P < .001). In study arm 1, therefore, trials 1 and 2 both showed fair interobserver agreement.

Study Arm 2: Glenoid Templating Based on 6 df

In study arm 2, a mean correlation of 0.42 (moderate agreement) was found between glenoid component size in 3-D templating and the glenoid component size ultimately selected during surgery (Table 3).

In study arm 2, overall intraobserver agreement was moderate. Among all surgeons who participated, intraobserver agreement was 0.80 (excellent), 0.43 (moderate), and 0.47 (moderate) for the 40-mm, 46-mm, and 52-mm glenoid components, respectively (overall κ = 0.58, moderate agreement). Trial 1 interobserver agreement was 0.75 (substantial) (P < .001), 0.39 (fair) (P < .001), and 0.50 (moderate) (P < .001) for the 40-mm, 46-mm, and 52-mm glenoid components, respectively (overall κ = 0.54, moderate agreement) (P < .001), and trial 2 interobserver agreement was 0.66 (substantial) (P < .001), 0.28 (fair) (P = .003), and 0.40 (moderate) (P < .001) for the 40-mm, 46-mm, and 52-mm glenoid components, respectively (overall κ = 0.43, moderate agreement) (P < .001). 

Discussion

Our results showed that 3-D glenoid templating had reproducible intraobserver and interobserver agreement. Overall intraobserver agreement was substantial (κ = 0.67) for study arm 1 and moderate (κ = 0.58) for study arm 2. Interobserver agreement was fair for trials 1 and 2 (κ = 0.36 and 0.32) in arm 1 and moderate for trials 1 and 2 (κ = 0.54 and 0.43) in arm 2.

Intraobserver and interobserver agreement values, particularly in study arm 2, which incorporated rotation (6 df), are consistent with values in commonly used classification systems, such as the Neer system for proximal humerus fractures, the Frykman system for distal radius fractures, and the King system for adolescent idiopathic scoliosis.^22-30 Sidor and colleagues²⁷ found overall interobserver agreement of 0.50 and overall intraobserver agreement of 0.66 for the Neer system, and Illarramendi and colleagues²⁴ found overall interobserver agreement of 0.43 and overall intraobserver agreement of 0.61 for the Frykman system.

In study arm 2, overall interobserver and intraobserver agreement was moderate. A higher level of surgeon agreement is unlikely given the lack of well-defined parameters for determining glenoid component size. Therefore, glenoid size selection is largely a matter of surgeon preference. More research is needed to establish concrete guidelines for glenoid component size selection. Once guidelines are adopted, interobserver agreement in templating may increase.

In both study arms, the component that surgeons selected during templating tended to be smaller than the component they selected during surgery. In study arm 1, 32% of patients had a smaller component selected based on computer modeling, and 7% had a larger component selected. In study arm 2, the difference was narrower: 27% of patients had a smaller component selected during templating, and 16% had a larger component selected. A statistically significant difference (P < .001) in templated and implanted component sizes was found between men and women: Templated glenoid components were smaller than implanted components in 53% of women and larger than implanted components in 33% of men. Differences between templated and implanted components may be attributable to visualization differences. During templating, the entire glenoid can be visualized and the slightest peg penetration or component overhang detected; in contrast, during surgery, anatomical constraints preclude such a comprehensive assessment.

Differences in agreement between templated and implanted glenoid components suggest that the size of implanted components may not be ideal. In this study, the distribution of the templated glenoid sizes was much wider than that of the implanted glenoid sizes. During templating, each glenoid component can be definitively visualized and assessed for possible peg penetration and overhang. Visualization allows surgeons to base glenoid size selection solely on glenoid morphology, as opposed to factors such as patient sex and height. In addition, interobserver and intraobserver agreement values for the 40-mm glenoid component were considerably higher than those for components of other sizes, indicating that the 40-mm component was consistently and reproducibly selected for the same patients. Hence, templating may particularly help prevent peg penetration and component overhang for patients with a smaller diameter glenoid.

More research on 3-D templating is warranted given the results of this study and other studies.^12,17,31 Scalise and colleagues³¹ found that, in TSA planning, surgeons’ use of 2-D (vs 3-D) imaging led them to overestimate glenoid component sizes (P = .006). In our study, the glenoid size selected during 3-D templating was, in many cases, smaller than the size selected during surgery. In order to avoid peg penetration and glenoid overhang, anecdotal guidelines commonly used in glenoid size selection, likely was the driving force in selecting smaller glenoid components during templating. Although anterior, superior, and inferior glenoid overhang typically can be assessed during surgery, posterior overhang is more difficult to evaluate. Three-dimensional modeling allows surgeons to determine optimal glenoid component size and position. In addition, intraoperative evaluation of glenoid component peg penetration is challenging, and peg penetration becomes evident only after it has occurred. During templating, however, surgeons were able to easily assess for peg penetration, and smaller glenoid components were selected.

A limitation of this study is that intraoperative glenoid version correction or peg containment was not quantified. More research is needed on the relationship between glenoid size selection and component overhang and peg penetration. Another limitation was use of only 1 TSA system (with 3 glenoid sizes, all with inline pegs); reliability of 3-D templating was not evaluated across different component designs. Last, given the absence of guidelines for glenoid component size selection, there was surgeon bias in preoperative templating and in intraoperative selection of glenoid size. Surgeons had differing opinions on the importance of maximizing the contact area of the component and correcting glenoid deformity and version.

Our study results showed that preoperative 3-D templating that allows for superior-inferior, anterior-posterior, and rotational translation was consistent and reproducible in determining glenoid component size, and use of this templating may reduce the risks of implant overhang, peg penetration, and decreased stability ratio. These results highlight the possibility that glenoid component sizes selected during surgery may not be ideal. More research is needed to determine if intraoperative glenoid size selection leads to adequate version correction and peg containment. The present study supports use of 3-D templating in primary TSA planning.

Take-Home Points

• Hockey is a high-speed collision sport with one of the highest injury rates among all sports.
• Use of a helmet with visors or full-face shields significantly reduces the risk for eye injury.
• Broken portions of teeth should be found and placed in a protective medium such as saline, saliva, or milk for transport.
• A player with unresolved concussion symptoms should not be allowed to return to the ice.
• Shoulder dominance, which determines stick grip, is an important consideration in the treatment of shoulder instability in an ice hockey player.

On a surface of ice in Windsor, Nova Scotia in the middle of the 19th century, the modern game of ice hockey evolved.¹ A blend of hurley, a Gaelic sport, and lacrosse, from the native Mi’kmaq culture, the sport of ice hockey gained rapidly in popularity throughout Canada and is now the country’s national sport. Hockey quickly spread to the United States and then Europe. It is presently played in 77 countries across the world.²

Hockey players can reach speeds of up to 48 km (~30 miles) per hour on razor-sharp skates on an ice surface surrounded by rigid plastic composite boards topped with plexiglass.³ They use sticks made of wood, aluminum, or a composite material to advance a 6-ounce vulcanized rubber puck on the opposing goal, and this puck sometimes reaches speeds over 160 km (~100 miles) per hour. Older, male players are allowed to make physical contact with their opposing counterparts to separate them from the puck (body-checking). Not surprisingly, the potential risk for injury in hockey is high. At the 2010 Winter Olympics, men’s ice hockey players had the highest rate of injury of any other competitors there—more than 30% were affected.⁴

Evaluation and Management of Common Hockey Injuries

Eye Injuries

Although eye injuries are less common than musculoskeletal injuries and concussions in hockey, they are a serious risk for recreational and competitive players alike. Furthermore, recovery may be difficult, and eye injuries can have serious lifelong consequences.⁸ In hockey, the most commonly reported eye injuries are periorbital contusions and lacerations, hyphema, corneal and conjunctival abrasions, orbital fractures, and ruptured globes (Table 2).^9,10

As a contact sport, hockey often involves high-impact, blunt-force trauma. The trauma in hockey results from collisions with other players, the boards, hockey sticks, and pucks. It is therefore not surprising that the most common ocular injuries in this sport are periorbital contusions. Although most contusions cause only mild swelling and ecchymosis of the soft tissues around the eye, there is potential for serious consequences. In a Scandinavia study, Leivo and colleagues¹⁰ found that 9% of patients who sustained a periocular contusion also had a clinically significant secondary diagnosis, such as retinal tear or hemorrhage, eyelid laceration, vitreous hemorrhage, or retinal detachment. Although the study was hospital-based, and therefore biased toward more severe cases, its findings highlight the potential severity of eye injuries in hockey. Furthermore, the study found that the majority of players who sustained blunt trauma to the eye itself required lifelong follow-up because of increased risk for glaucoma. This is particularly true for hyphema, as this finding indicates significant damage to intraocular tissues.¹⁰Players can also sustain fractures of the orbital bones, including orbital blowout fractures. Typical signs and symptoms of blowout fractures include diplopia, proptosis or enophthalmos, infraorbital hypoesthesia, painful and decreased extraocular movement (particularly upgaze), and palpable crepitance caused by sinus air entering the lower eyelid.¹¹ If orbital fracture is suspected, as it should be in any case in which the injured player experiences pain with eye movement or diplopia, the player should be referred to the ED for computed tomography (CT) and ophthalmologic evaluation.¹² Continued participation seriously risks making the injury much worse, particularly should another impact occur. In addition, given the impact needed to cause orbital fractures, consideration must be given to the potential for a coexisting concussion injury.

Severe direct trauma to the eye—from a puck, a stick, or a fist—can result in a ruptured globe, a particularly serious injury that requires immediate surgical attention. Signs and symptoms of a ruptured globe are rarely subtle, but associated eyelid swelling or laceration may obscure the injury, delaying proper diagnosis and treatment. More obvious signs include severely reduced vision, hemorrhagic chemosis (swelling) of the conjunctiva, and an irregular or peaked pupil. If a rupture or any significant intraocular injury is suspected, it is crucial to avoid applying any pressure to the globe, as this can significantly worsen the damage to the intraocular tissues. Use of a helmet with protective shields and cages attached markedly reduces the risk for such injuries.¹³All eye injuries require prompt assessment, which allows for appropriate management and prevention of secondary damage.¹⁴ Initial evaluation of a patient with ocular trauma should begin with external examination for lacerations, swelling, or orbital rim step-off deformity. The physician should also check visual acuity in order to assess for significant vision impairment (counting fingers or reading a sign in the arena; confrontation visual fields). This should be done before attending to any periocular injuries, with the uninjured side serving as a control. Next, the physician should assess the extraocular eye movements as well as the size, shape, and reactivity of the pupils. Particular attention should be paid to detecting any deficit in extraocular movement or irregularity in pupil size, shape, or reactivity, as such findings are highly suggestive of serious injury to the globe.¹³ Hyphema (blood in anterior chamber of eye anterior to pupil) should be suspected if vision is reduced and the pupil cannot be clearly visualized. However, a bright red clot is not always apparent at time of injury or if the amount of blood is small. An irregular pupil, or a pupil that does not constrict well to light, is also a red flag for serious contusion injury to the eye, and requires ophthalmologic evaluation. It is important to keep in mind that blunt trauma severe enough to produce hyphema or an irregular and poorly reactive pupil is often associated with retinal damage as well, including retinal edema or detachment.

Minor injuries (eg, small foreign bodies, minor periocular contusions and lacerations) can often be managed rink-side. Foreign bodies not embedded in the cornea, but lodged under the upper eyelid, can sometimes be removed by everting the eyelid and sweeping with a moistened cotton swab or using diffuse, sterile saline irrigation.¹¹ Corneal abrasions generally cause severe pain, photophobia, and tearing and are easily diagnosed with use of topical fluorescein and a blue light. A topical anesthetic can be extremely helpful in this setting, as it allows for proper pain-free evaluation, but should never be used in an ongoing manner for pain relief. Small lacerations of the brow can be sutured with 5-0 or 6-0 nylon or closed with 2-Octyl cyanoacrylate tissue adhesive (Dermabond). Eyelid lacerations, unless very small, are best managed by an ophthalmologist; care must be taken to rule out injury to the deeper orbital tissues and eye. If serious injury is suspected, or the eye cannot be appropriately evaluated, it should be stabilized and protected with a protective shield or plastic cup, and the player should be transferred to an ED for appropriate ophthalmologic evaluation.¹³Most eye injuries are accidental, caused by sticks or deflected pucks, but 18% are acquired in fights.⁸ Use of visors or full-face cages effectively minimizes the rate of eye injuries.^8,13,15,16 In a cohort study of 282 elite amateur ice hockey players, the risk of eye injury was 4.7 times higher in players without face protection than in players who used half-face shields; there were no eye injuries in players who used full-face protection.¹³ For visors to prevent eye injury, they must be positioned to cover the eyes and the lower edge of the nose in all projections.¹⁰

Dental Injuries

The incidence and type of facial and dental injuries depend directly on the type of face protection used.^11,17,18 In a study of face, head, and neck injuries in elite amateur ice hockey players, Stuart and colleagues¹³ found game-related injury rates of 158.9 per 1000 player-hours in players without face protection, 73.5 in players who used half-face shields, and 23.2 in players who used full-face shields. Players who wore full-face shields had facial, head, and neck injury rates of only 23.2 per 1000 player-game hours.¹³ Other studies clearly support the important role face shields play in lowering injury risk in hockey. Face and head injuries account for 20% to 40% of all hockey-related injuries,^3,16,19 and dental injuries up to 11.5%.²⁰ In a study from Finland, Lahti and colleagues¹⁹ found that over a 2-year period, 479 hockey players sustained injuries, including 650 separate dental injuries. The most commonly diagnosed dental injury was an uncomplicated crown fracture, and the most common cause was a hit with a hockey stick, which accounted for 52.7% and 40.3% of dental injuries in games and practices, respectively.¹⁹

In the management of dental fractures, the broken portions of teeth should be found and placed in a transportation-protective medium, such as saline, saliva, or milk,¹⁶ which can improve functional and esthetic replacement outcomes.^21,22 Loose pieces of teeth should not be left in the player’s mouth. The residual tooth should be stabilized and exposure to air and occlusion limited. Dental fractures can affect the enamel, the enamel and dentin structures (uncomplicated fracture), or enamel, dentin, and pulp (complicated).²³ Fractures involving only the enamel do not require urgent dental evaluation. Dentin or pulp involvement may cause temperature and air sensitivity.²³ If a tooth is air-sensitive, the player should be referred to a specialist immediately.¹¹

Direct trauma can cause instability without displacement (subluxation) or complete displacement of the tooth from its alveolar socket (avulsion).²³ An avulsed tooth should be handled by the crown to avoid further damage to the root and periodontal ligament.^16,24 The tooth should be rinsed gently with saline and reimplanted in its socket, ideally within 5 to 10 minutes,²³with the athlete biting down gently on gauze to hold the tooth in place. A 1-mL supraperiosteal infiltration of 1% or 2% lidocaine hydrochloride (1:100,000 epinephrine) can be given into the apex of the tooth being anesthetized (Figure 1).

Concussions

A concussion is a “complex pathophysiological process affecting the brain, induced by traumatic biomechanical forces.”²⁵ Concussion is largely a functional disturbance instead of a structural injury, owing to the rotational and/or shearing forces involved. Many studies have identified concussion as the most common type of injury in all of youth hockey.²⁶ Concussions account for up to 19% of all injuries in men’s collegiate hockey.³

Concussion can be challenging to diagnose on the ice. The most important factor in concussion management is symptom reporting by the athlete.²⁷ Despite significant efforts in education and awareness, student athletes, especially hockey players, withhold reporting a possible concussion.²⁸ Reasons for underreporting include fear of letting down other players and coaches, thinking the injury is not severe enough to warrant evaluation, and fear of losing standing with the current team or future teams.²⁸

Cervical Spine Injuries

Whereas American football is associated with a higher annual number of nonfatal catastrophic neck injuries, hockey has a 3 to 6 times higher incidence of cervical spine injuries and spinal cord damage.^38,39 A Canadian Ice Hockey Spinal Injuries Registry review of the period 2006 to 2011 identified 44 cervical spine injuries, 7.3 per year on average.⁴⁰ Severe injury, defined as complete motor and sensory loss, complete motor loss and incomplete sensory, or complete motor loss, occurred in 4 (9.1%) of the 44 injured players. In hockey, a major mechanism of cervical spine injury is an axial load to the slightly flexed spine.³⁹ Of 355 hockey-related cervical spine injuries in a Canada study, 95 (35.5%) were caused by a check from behind.^40,41 The Canadian neurosurgeons’ work led to rule changes prohibiting checks from behind, and this prohibition has reduced the incidence of cervical spine injuries in ice hockey.^38,40

Team physicians should be comfortable managing serious neck and spine injuries on the ice. Initial evaluation should follow the standard ABCs (airway, breathing, circulation). The physician places a hand on each side of the head to stabilize the neck until the initial examination is complete. The goal is to minimize cervical spine motion until transportation to the hospital for advanced imaging and definitive treatment.³⁷ The decision to remove or leave on the helmet is now controversial. Hockey helmets differ from football helmets in that their chinstraps do not afford significant cervical stabilization, and the helmets have less padding and cover less of the head; in addition, a shockingly high percentage of hockey players do not wear properly fitting helmets.³⁷ In one study, 3-dimensional motion analysis of a hockey player during the logroll technique showed less transverse and sagittal cervical plane motion with the helmet removed than with the helmet (properly fitting or not) in place; the authors recommended removing the helmet to limit extraneous cervical spine motion during the technique.³⁷ However, 2 other studies found that helmet removal can result in significantly increased cervical spine motion of the immobilized hockey player.^42,43Recommendation 4 of the recently released interassociation consensus statement of the National Athletic Trainers’ Association reads, “Protective athletic equipment should be removed before transport to an emergency facility for an athlete-patient with suspected cervical spine instability.”⁴⁴ This represents a shift from leaving the helmet and shoulder pads in place. For ice hockey players with suspected cervical spine injury, more research is needed on cervical motion during the entire sequence—partial logrolls, spine-boarding, placement of cervical collar before or after logroll, and different immobilization techniques for transport.³⁷

The athlete must be carefully transferred to a spine board with either logroll or lift-and-slide. Although an extrication cervical collar can be placed before the spine board is placed, the effectiveness of this collar in executing the spine-board transfer is not proven.⁴⁵ When the player is on the spine board, the head can be secured with pads and straps en route to the hospital.

Return-to-Play Criteria for Cervical Spine Injuries There is no clear consensus on return-to-play guidelines for cervical spine injuries in athletes.⁴⁶

Shoulder Injuries

For hockey players, the upper extremity traditionally has been considered a well-protected area.⁴⁸ However, shoulder pads are considerably more flexible in hockey than in football and other collision sports. In addition, hockey gloves allow a fair amount of motion for stick handling, and the wrist may be in maximal flexion or extension when a hit against the boards or the ice occurs. Open-ice checking, board collisions, and hockey stick use have been postulated as reasons for the high incidence of upper extremity injuries in hockey. Researchers in Finland found that upper extremity injuries accounted for up to 31% of all hockey injuries.⁴⁹ More than 50% of these injuries resulted from checking or board collisions. Furthermore, study findings highlighted a low rate of injury in younger players and indicated the rate increases with age.^49,50

In hockey players, the acromioclavicular (AC) joint is the most commonly injured shoulder structure.⁵¹ The mechanism of injury can be a board collision or an open-ice hit, but most often is a direct blow to the shoulder. The collision disrupts the AC joint and can sprain or tear the coracoclavicular ligaments. The Rockwood classification is used to categorize AC joint injuries (Figure 2).

Summary

Hockey is a high-speed collision sport with one of the highest injury rates among all sports. Physicians caring for youth, amateur, and senior hockey teams see a range of acute head, neck, and shoulder injuries. Although treatment of eye injuries, dental injuries, and concussions is not always considered orthopedic care, an orthopedic surgeon who is covering hockey needs to be comfortable managing these injuries acutely. Quality rink-side care minimizes the impact of the injury, maximizes the functional result, and expedites the safe return of the injured player back to the ice.

Am J Orthop. 2017;46(3):123-134. Copyright Frontline Medical Communications Inc. 2017. All rights reserved.

Take-Home Points

• Hockey is a high-speed collision sport with one of the highest injury rates among all sports.
• Use of a helmet with visors or full-face shields significantly reduces the risk for eye injury.
• Broken portions of teeth should be found and placed in a protective medium such as saline, saliva, or milk for transport.
• A player with unresolved concussion symptoms should not be allowed to return to the ice.
• Shoulder dominance, which determines stick grip, is an important consideration in the treatment of shoulder instability in an ice hockey player.

On a surface of ice in Windsor, Nova Scotia in the middle of the 19th century, the modern game of ice hockey evolved.¹ A blend of hurley, a Gaelic sport, and lacrosse, from the native Mi’kmaq culture, the sport of ice hockey gained rapidly in popularity throughout Canada and is now the country’s national sport. Hockey quickly spread to the United States and then Europe. It is presently played in 77 countries across the world.²

Hockey players can reach speeds of up to 48 km (~30 miles) per hour on razor-sharp skates on an ice surface surrounded by rigid plastic composite boards topped with plexiglass.³ They use sticks made of wood, aluminum, or a composite material to advance a 6-ounce vulcanized rubber puck on the opposing goal, and this puck sometimes reaches speeds over 160 km (~100 miles) per hour. Older, male players are allowed to make physical contact with their opposing counterparts to separate them from the puck (body-checking). Not surprisingly, the potential risk for injury in hockey is high. At the 2010 Winter Olympics, men’s ice hockey players had the highest rate of injury of any other competitors there—more than 30% were affected.⁴

Evaluation and Management of Common Hockey Injuries

Eye Injuries

Although eye injuries are less common than musculoskeletal injuries and concussions in hockey, they are a serious risk for recreational and competitive players alike. Furthermore, recovery may be difficult, and eye injuries can have serious lifelong consequences.⁸ In hockey, the most commonly reported eye injuries are periorbital contusions and lacerations, hyphema, corneal and conjunctival abrasions, orbital fractures, and ruptured globes (Table 2).^9,10

As a contact sport, hockey often involves high-impact, blunt-force trauma. The trauma in hockey results from collisions with other players, the boards, hockey sticks, and pucks. It is therefore not surprising that the most common ocular injuries in this sport are periorbital contusions. Although most contusions cause only mild swelling and ecchymosis of the soft tissues around the eye, there is potential for serious consequences. In a Scandinavia study, Leivo and colleagues¹⁰ found that 9% of patients who sustained a periocular contusion also had a clinically significant secondary diagnosis, such as retinal tear or hemorrhage, eyelid laceration, vitreous hemorrhage, or retinal detachment. Although the study was hospital-based, and therefore biased toward more severe cases, its findings highlight the potential severity of eye injuries in hockey. Furthermore, the study found that the majority of players who sustained blunt trauma to the eye itself required lifelong follow-up because of increased risk for glaucoma. This is particularly true for hyphema, as this finding indicates significant damage to intraocular tissues.¹⁰Players can also sustain fractures of the orbital bones, including orbital blowout fractures. Typical signs and symptoms of blowout fractures include diplopia, proptosis or enophthalmos, infraorbital hypoesthesia, painful and decreased extraocular movement (particularly upgaze), and palpable crepitance caused by sinus air entering the lower eyelid.¹¹ If orbital fracture is suspected, as it should be in any case in which the injured player experiences pain with eye movement or diplopia, the player should be referred to the ED for computed tomography (CT) and ophthalmologic evaluation.¹² Continued participation seriously risks making the injury much worse, particularly should another impact occur. In addition, given the impact needed to cause orbital fractures, consideration must be given to the potential for a coexisting concussion injury.

Severe direct trauma to the eye—from a puck, a stick, or a fist—can result in a ruptured globe, a particularly serious injury that requires immediate surgical attention. Signs and symptoms of a ruptured globe are rarely subtle, but associated eyelid swelling or laceration may obscure the injury, delaying proper diagnosis and treatment. More obvious signs include severely reduced vision, hemorrhagic chemosis (swelling) of the conjunctiva, and an irregular or peaked pupil. If a rupture or any significant intraocular injury is suspected, it is crucial to avoid applying any pressure to the globe, as this can significantly worsen the damage to the intraocular tissues. Use of a helmet with protective shields and cages attached markedly reduces the risk for such injuries.¹³All eye injuries require prompt assessment, which allows for appropriate management and prevention of secondary damage.¹⁴ Initial evaluation of a patient with ocular trauma should begin with external examination for lacerations, swelling, or orbital rim step-off deformity. The physician should also check visual acuity in order to assess for significant vision impairment (counting fingers or reading a sign in the arena; confrontation visual fields). This should be done before attending to any periocular injuries, with the uninjured side serving as a control. Next, the physician should assess the extraocular eye movements as well as the size, shape, and reactivity of the pupils. Particular attention should be paid to detecting any deficit in extraocular movement or irregularity in pupil size, shape, or reactivity, as such findings are highly suggestive of serious injury to the globe.¹³ Hyphema (blood in anterior chamber of eye anterior to pupil) should be suspected if vision is reduced and the pupil cannot be clearly visualized. However, a bright red clot is not always apparent at time of injury or if the amount of blood is small. An irregular pupil, or a pupil that does not constrict well to light, is also a red flag for serious contusion injury to the eye, and requires ophthalmologic evaluation. It is important to keep in mind that blunt trauma severe enough to produce hyphema or an irregular and poorly reactive pupil is often associated with retinal damage as well, including retinal edema or detachment.

Minor injuries (eg, small foreign bodies, minor periocular contusions and lacerations) can often be managed rink-side. Foreign bodies not embedded in the cornea, but lodged under the upper eyelid, can sometimes be removed by everting the eyelid and sweeping with a moistened cotton swab or using diffuse, sterile saline irrigation.¹¹ Corneal abrasions generally cause severe pain, photophobia, and tearing and are easily diagnosed with use of topical fluorescein and a blue light. A topical anesthetic can be extremely helpful in this setting, as it allows for proper pain-free evaluation, but should never be used in an ongoing manner for pain relief. Small lacerations of the brow can be sutured with 5-0 or 6-0 nylon or closed with 2-Octyl cyanoacrylate tissue adhesive (Dermabond). Eyelid lacerations, unless very small, are best managed by an ophthalmologist; care must be taken to rule out injury to the deeper orbital tissues and eye. If serious injury is suspected, or the eye cannot be appropriately evaluated, it should be stabilized and protected with a protective shield or plastic cup, and the player should be transferred to an ED for appropriate ophthalmologic evaluation.¹³Most eye injuries are accidental, caused by sticks or deflected pucks, but 18% are acquired in fights.⁸ Use of visors or full-face cages effectively minimizes the rate of eye injuries.^8,13,15,16 In a cohort study of 282 elite amateur ice hockey players, the risk of eye injury was 4.7 times higher in players without face protection than in players who used half-face shields; there were no eye injuries in players who used full-face protection.¹³ For visors to prevent eye injury, they must be positioned to cover the eyes and the lower edge of the nose in all projections.¹⁰

Dental Injuries

The incidence and type of facial and dental injuries depend directly on the type of face protection used.^11,17,18 In a study of face, head, and neck injuries in elite amateur ice hockey players, Stuart and colleagues¹³ found game-related injury rates of 158.9 per 1000 player-hours in players without face protection, 73.5 in players who used half-face shields, and 23.2 in players who used full-face shields. Players who wore full-face shields had facial, head, and neck injury rates of only 23.2 per 1000 player-game hours.¹³ Other studies clearly support the important role face shields play in lowering injury risk in hockey. Face and head injuries account for 20% to 40% of all hockey-related injuries,^3,16,19 and dental injuries up to 11.5%.²⁰ In a study from Finland, Lahti and colleagues¹⁹ found that over a 2-year period, 479 hockey players sustained injuries, including 650 separate dental injuries. The most commonly diagnosed dental injury was an uncomplicated crown fracture, and the most common cause was a hit with a hockey stick, which accounted for 52.7% and 40.3% of dental injuries in games and practices, respectively.¹⁹

In the management of dental fractures, the broken portions of teeth should be found and placed in a transportation-protective medium, such as saline, saliva, or milk,¹⁶ which can improve functional and esthetic replacement outcomes.^21,22 Loose pieces of teeth should not be left in the player’s mouth. The residual tooth should be stabilized and exposure to air and occlusion limited. Dental fractures can affect the enamel, the enamel and dentin structures (uncomplicated fracture), or enamel, dentin, and pulp (complicated).²³ Fractures involving only the enamel do not require urgent dental evaluation. Dentin or pulp involvement may cause temperature and air sensitivity.²³ If a tooth is air-sensitive, the player should be referred to a specialist immediately.¹¹

Direct trauma can cause instability without displacement (subluxation) or complete displacement of the tooth from its alveolar socket (avulsion).²³ An avulsed tooth should be handled by the crown to avoid further damage to the root and periodontal ligament.^16,24 The tooth should be rinsed gently with saline and reimplanted in its socket, ideally within 5 to 10 minutes,²³with the athlete biting down gently on gauze to hold the tooth in place. A 1-mL supraperiosteal infiltration of 1% or 2% lidocaine hydrochloride (1:100,000 epinephrine) can be given into the apex of the tooth being anesthetized (Figure 1).

Concussions

A concussion is a “complex pathophysiological process affecting the brain, induced by traumatic biomechanical forces.”²⁵ Concussion is largely a functional disturbance instead of a structural injury, owing to the rotational and/or shearing forces involved. Many studies have identified concussion as the most common type of injury in all of youth hockey.²⁶ Concussions account for up to 19% of all injuries in men’s collegiate hockey.³

Concussion can be challenging to diagnose on the ice. The most important factor in concussion management is symptom reporting by the athlete.²⁷ Despite significant efforts in education and awareness, student athletes, especially hockey players, withhold reporting a possible concussion.²⁸ Reasons for underreporting include fear of letting down other players and coaches, thinking the injury is not severe enough to warrant evaluation, and fear of losing standing with the current team or future teams.²⁸

Cervical Spine Injuries

Whereas American football is associated with a higher annual number of nonfatal catastrophic neck injuries, hockey has a 3 to 6 times higher incidence of cervical spine injuries and spinal cord damage.^38,39 A Canadian Ice Hockey Spinal Injuries Registry review of the period 2006 to 2011 identified 44 cervical spine injuries, 7.3 per year on average.⁴⁰ Severe injury, defined as complete motor and sensory loss, complete motor loss and incomplete sensory, or complete motor loss, occurred in 4 (9.1%) of the 44 injured players. In hockey, a major mechanism of cervical spine injury is an axial load to the slightly flexed spine.³⁹ Of 355 hockey-related cervical spine injuries in a Canada study, 95 (35.5%) were caused by a check from behind.^40,41 The Canadian neurosurgeons’ work led to rule changes prohibiting checks from behind, and this prohibition has reduced the incidence of cervical spine injuries in ice hockey.^38,40

Team physicians should be comfortable managing serious neck and spine injuries on the ice. Initial evaluation should follow the standard ABCs (airway, breathing, circulation). The physician places a hand on each side of the head to stabilize the neck until the initial examination is complete. The goal is to minimize cervical spine motion until transportation to the hospital for advanced imaging and definitive treatment.³⁷ The decision to remove or leave on the helmet is now controversial. Hockey helmets differ from football helmets in that their chinstraps do not afford significant cervical stabilization, and the helmets have less padding and cover less of the head; in addition, a shockingly high percentage of hockey players do not wear properly fitting helmets.³⁷ In one study, 3-dimensional motion analysis of a hockey player during the logroll technique showed less transverse and sagittal cervical plane motion with the helmet removed than with the helmet (properly fitting or not) in place; the authors recommended removing the helmet to limit extraneous cervical spine motion during the technique.³⁷ However, 2 other studies found that helmet removal can result in significantly increased cervical spine motion of the immobilized hockey player.^42,43Recommendation 4 of the recently released interassociation consensus statement of the National Athletic Trainers’ Association reads, “Protective athletic equipment should be removed before transport to an emergency facility for an athlete-patient with suspected cervical spine instability.”⁴⁴ This represents a shift from leaving the helmet and shoulder pads in place. For ice hockey players with suspected cervical spine injury, more research is needed on cervical motion during the entire sequence—partial logrolls, spine-boarding, placement of cervical collar before or after logroll, and different immobilization techniques for transport.³⁷

The athlete must be carefully transferred to a spine board with either logroll or lift-and-slide. Although an extrication cervical collar can be placed before the spine board is placed, the effectiveness of this collar in executing the spine-board transfer is not proven.⁴⁵ When the player is on the spine board, the head can be secured with pads and straps en route to the hospital.

Return-to-Play Criteria for Cervical Spine Injuries There is no clear consensus on return-to-play guidelines for cervical spine injuries in athletes.⁴⁶

Shoulder Injuries

For hockey players, the upper extremity traditionally has been considered a well-protected area.⁴⁸ However, shoulder pads are considerably more flexible in hockey than in football and other collision sports. In addition, hockey gloves allow a fair amount of motion for stick handling, and the wrist may be in maximal flexion or extension when a hit against the boards or the ice occurs. Open-ice checking, board collisions, and hockey stick use have been postulated as reasons for the high incidence of upper extremity injuries in hockey. Researchers in Finland found that upper extremity injuries accounted for up to 31% of all hockey injuries.⁴⁹ More than 50% of these injuries resulted from checking or board collisions. Furthermore, study findings highlighted a low rate of injury in younger players and indicated the rate increases with age.^49,50

In hockey players, the acromioclavicular (AC) joint is the most commonly injured shoulder structure.⁵¹ The mechanism of injury can be a board collision or an open-ice hit, but most often is a direct blow to the shoulder. The collision disrupts the AC joint and can sprain or tear the coracoclavicular ligaments. The Rockwood classification is used to categorize AC joint injuries (Figure 2).

Summary

Hockey is a high-speed collision sport with one of the highest injury rates among all sports. Physicians caring for youth, amateur, and senior hockey teams see a range of acute head, neck, and shoulder injuries. Although treatment of eye injuries, dental injuries, and concussions is not always considered orthopedic care, an orthopedic surgeon who is covering hockey needs to be comfortable managing these injuries acutely. Quality rink-side care minimizes the impact of the injury, maximizes the functional result, and expedites the safe return of the injured player back to the ice.

Am J Orthop. 2017;46(3):123-134. Copyright Frontline Medical Communications Inc. 2017. All rights reserved.

Take-Home Points

• Hockey is a high-speed collision sport with one of the highest injury rates among all sports.
• Use of a helmet with visors or full-face shields significantly reduces the risk for eye injury.
• Broken portions of teeth should be found and placed in a protective medium such as saline, saliva, or milk for transport.
• A player with unresolved concussion symptoms should not be allowed to return to the ice.
• Shoulder dominance, which determines stick grip, is an important consideration in the treatment of shoulder instability in an ice hockey player.

On a surface of ice in Windsor, Nova Scotia in the middle of the 19th century, the modern game of ice hockey evolved.¹ A blend of hurley, a Gaelic sport, and lacrosse, from the native Mi’kmaq culture, the sport of ice hockey gained rapidly in popularity throughout Canada and is now the country’s national sport. Hockey quickly spread to the United States and then Europe. It is presently played in 77 countries across the world.²

Hockey players can reach speeds of up to 48 km (~30 miles) per hour on razor-sharp skates on an ice surface surrounded by rigid plastic composite boards topped with plexiglass.³ They use sticks made of wood, aluminum, or a composite material to advance a 6-ounce vulcanized rubber puck on the opposing goal, and this puck sometimes reaches speeds over 160 km (~100 miles) per hour. Older, male players are allowed to make physical contact with their opposing counterparts to separate them from the puck (body-checking). Not surprisingly, the potential risk for injury in hockey is high. At the 2010 Winter Olympics, men’s ice hockey players had the highest rate of injury of any other competitors there—more than 30% were affected.⁴

Evaluation and Management of Common Hockey Injuries

Eye Injuries

Although eye injuries are less common than musculoskeletal injuries and concussions in hockey, they are a serious risk for recreational and competitive players alike. Furthermore, recovery may be difficult, and eye injuries can have serious lifelong consequences.⁸ In hockey, the most commonly reported eye injuries are periorbital contusions and lacerations, hyphema, corneal and conjunctival abrasions, orbital fractures, and ruptured globes (Table 2).^9,10

As a contact sport, hockey often involves high-impact, blunt-force trauma. The trauma in hockey results from collisions with other players, the boards, hockey sticks, and pucks. It is therefore not surprising that the most common ocular injuries in this sport are periorbital contusions. Although most contusions cause only mild swelling and ecchymosis of the soft tissues around the eye, there is potential for serious consequences. In a Scandinavia study, Leivo and colleagues¹⁰ found that 9% of patients who sustained a periocular contusion also had a clinically significant secondary diagnosis, such as retinal tear or hemorrhage, eyelid laceration, vitreous hemorrhage, or retinal detachment. Although the study was hospital-based, and therefore biased toward more severe cases, its findings highlight the potential severity of eye injuries in hockey. Furthermore, the study found that the majority of players who sustained blunt trauma to the eye itself required lifelong follow-up because of increased risk for glaucoma. This is particularly true for hyphema, as this finding indicates significant damage to intraocular tissues.¹⁰Players can also sustain fractures of the orbital bones, including orbital blowout fractures. Typical signs and symptoms of blowout fractures include diplopia, proptosis or enophthalmos, infraorbital hypoesthesia, painful and decreased extraocular movement (particularly upgaze), and palpable crepitance caused by sinus air entering the lower eyelid.¹¹ If orbital fracture is suspected, as it should be in any case in which the injured player experiences pain with eye movement or diplopia, the player should be referred to the ED for computed tomography (CT) and ophthalmologic evaluation.¹² Continued participation seriously risks making the injury much worse, particularly should another impact occur. In addition, given the impact needed to cause orbital fractures, consideration must be given to the potential for a coexisting concussion injury.

Severe direct trauma to the eye—from a puck, a stick, or a fist—can result in a ruptured globe, a particularly serious injury that requires immediate surgical attention. Signs and symptoms of a ruptured globe are rarely subtle, but associated eyelid swelling or laceration may obscure the injury, delaying proper diagnosis and treatment. More obvious signs include severely reduced vision, hemorrhagic chemosis (swelling) of the conjunctiva, and an irregular or peaked pupil. If a rupture or any significant intraocular injury is suspected, it is crucial to avoid applying any pressure to the globe, as this can significantly worsen the damage to the intraocular tissues. Use of a helmet with protective shields and cages attached markedly reduces the risk for such injuries.¹³All eye injuries require prompt assessment, which allows for appropriate management and prevention of secondary damage.¹⁴ Initial evaluation of a patient with ocular trauma should begin with external examination for lacerations, swelling, or orbital rim step-off deformity. The physician should also check visual acuity in order to assess for significant vision impairment (counting fingers or reading a sign in the arena; confrontation visual fields). This should be done before attending to any periocular injuries, with the uninjured side serving as a control. Next, the physician should assess the extraocular eye movements as well as the size, shape, and reactivity of the pupils. Particular attention should be paid to detecting any deficit in extraocular movement or irregularity in pupil size, shape, or reactivity, as such findings are highly suggestive of serious injury to the globe.¹³ Hyphema (blood in anterior chamber of eye anterior to pupil) should be suspected if vision is reduced and the pupil cannot be clearly visualized. However, a bright red clot is not always apparent at time of injury or if the amount of blood is small. An irregular pupil, or a pupil that does not constrict well to light, is also a red flag for serious contusion injury to the eye, and requires ophthalmologic evaluation. It is important to keep in mind that blunt trauma severe enough to produce hyphema or an irregular and poorly reactive pupil is often associated with retinal damage as well, including retinal edema or detachment.

Minor injuries (eg, small foreign bodies, minor periocular contusions and lacerations) can often be managed rink-side. Foreign bodies not embedded in the cornea, but lodged under the upper eyelid, can sometimes be removed by everting the eyelid and sweeping with a moistened cotton swab or using diffuse, sterile saline irrigation.¹¹ Corneal abrasions generally cause severe pain, photophobia, and tearing and are easily diagnosed with use of topical fluorescein and a blue light. A topical anesthetic can be extremely helpful in this setting, as it allows for proper pain-free evaluation, but should never be used in an ongoing manner for pain relief. Small lacerations of the brow can be sutured with 5-0 or 6-0 nylon or closed with 2-Octyl cyanoacrylate tissue adhesive (Dermabond). Eyelid lacerations, unless very small, are best managed by an ophthalmologist; care must be taken to rule out injury to the deeper orbital tissues and eye. If serious injury is suspected, or the eye cannot be appropriately evaluated, it should be stabilized and protected with a protective shield or plastic cup, and the player should be transferred to an ED for appropriate ophthalmologic evaluation.¹³Most eye injuries are accidental, caused by sticks or deflected pucks, but 18% are acquired in fights.⁸ Use of visors or full-face cages effectively minimizes the rate of eye injuries.^8,13,15,16 In a cohort study of 282 elite amateur ice hockey players, the risk of eye injury was 4.7 times higher in players without face protection than in players who used half-face shields; there were no eye injuries in players who used full-face protection.¹³ For visors to prevent eye injury, they must be positioned to cover the eyes and the lower edge of the nose in all projections.¹⁰

Dental Injuries

The incidence and type of facial and dental injuries depend directly on the type of face protection used.^11,17,18 In a study of face, head, and neck injuries in elite amateur ice hockey players, Stuart and colleagues¹³ found game-related injury rates of 158.9 per 1000 player-hours in players without face protection, 73.5 in players who used half-face shields, and 23.2 in players who used full-face shields. Players who wore full-face shields had facial, head, and neck injury rates of only 23.2 per 1000 player-game hours.¹³ Other studies clearly support the important role face shields play in lowering injury risk in hockey. Face and head injuries account for 20% to 40% of all hockey-related injuries,^3,16,19 and dental injuries up to 11.5%.²⁰ In a study from Finland, Lahti and colleagues¹⁹ found that over a 2-year period, 479 hockey players sustained injuries, including 650 separate dental injuries. The most commonly diagnosed dental injury was an uncomplicated crown fracture, and the most common cause was a hit with a hockey stick, which accounted for 52.7% and 40.3% of dental injuries in games and practices, respectively.¹⁹

In the management of dental fractures, the broken portions of teeth should be found and placed in a transportation-protective medium, such as saline, saliva, or milk,¹⁶ which can improve functional and esthetic replacement outcomes.^21,22 Loose pieces of teeth should not be left in the player’s mouth. The residual tooth should be stabilized and exposure to air and occlusion limited. Dental fractures can affect the enamel, the enamel and dentin structures (uncomplicated fracture), or enamel, dentin, and pulp (complicated).²³ Fractures involving only the enamel do not require urgent dental evaluation. Dentin or pulp involvement may cause temperature and air sensitivity.²³ If a tooth is air-sensitive, the player should be referred to a specialist immediately.¹¹

Direct trauma can cause instability without displacement (subluxation) or complete displacement of the tooth from its alveolar socket (avulsion).²³ An avulsed tooth should be handled by the crown to avoid further damage to the root and periodontal ligament.^16,24 The tooth should be rinsed gently with saline and reimplanted in its socket, ideally within 5 to 10 minutes,²³with the athlete biting down gently on gauze to hold the tooth in place. A 1-mL supraperiosteal infiltration of 1% or 2% lidocaine hydrochloride (1:100,000 epinephrine) can be given into the apex of the tooth being anesthetized (Figure 1).

Concussions

A concussion is a “complex pathophysiological process affecting the brain, induced by traumatic biomechanical forces.”²⁵ Concussion is largely a functional disturbance instead of a structural injury, owing to the rotational and/or shearing forces involved. Many studies have identified concussion as the most common type of injury in all of youth hockey.²⁶ Concussions account for up to 19% of all injuries in men’s collegiate hockey.³

Concussion can be challenging to diagnose on the ice. The most important factor in concussion management is symptom reporting by the athlete.²⁷ Despite significant efforts in education and awareness, student athletes, especially hockey players, withhold reporting a possible concussion.²⁸ Reasons for underreporting include fear of letting down other players and coaches, thinking the injury is not severe enough to warrant evaluation, and fear of losing standing with the current team or future teams.²⁸

Cervical Spine Injuries

Whereas American football is associated with a higher annual number of nonfatal catastrophic neck injuries, hockey has a 3 to 6 times higher incidence of cervical spine injuries and spinal cord damage.^38,39 A Canadian Ice Hockey Spinal Injuries Registry review of the period 2006 to 2011 identified 44 cervical spine injuries, 7.3 per year on average.⁴⁰ Severe injury, defined as complete motor and sensory loss, complete motor loss and incomplete sensory, or complete motor loss, occurred in 4 (9.1%) of the 44 injured players. In hockey, a major mechanism of cervical spine injury is an axial load to the slightly flexed spine.³⁹ Of 355 hockey-related cervical spine injuries in a Canada study, 95 (35.5%) were caused by a check from behind.^40,41 The Canadian neurosurgeons’ work led to rule changes prohibiting checks from behind, and this prohibition has reduced the incidence of cervical spine injuries in ice hockey.^38,40

Team physicians should be comfortable managing serious neck and spine injuries on the ice. Initial evaluation should follow the standard ABCs (airway, breathing, circulation). The physician places a hand on each side of the head to stabilize the neck until the initial examination is complete. The goal is to minimize cervical spine motion until transportation to the hospital for advanced imaging and definitive treatment.³⁷ The decision to remove or leave on the helmet is now controversial. Hockey helmets differ from football helmets in that their chinstraps do not afford significant cervical stabilization, and the helmets have less padding and cover less of the head; in addition, a shockingly high percentage of hockey players do not wear properly fitting helmets.³⁷ In one study, 3-dimensional motion analysis of a hockey player during the logroll technique showed less transverse and sagittal cervical plane motion with the helmet removed than with the helmet (properly fitting or not) in place; the authors recommended removing the helmet to limit extraneous cervical spine motion during the technique.³⁷ However, 2 other studies found that helmet removal can result in significantly increased cervical spine motion of the immobilized hockey player.^42,43Recommendation 4 of the recently released interassociation consensus statement of the National Athletic Trainers’ Association reads, “Protective athletic equipment should be removed before transport to an emergency facility for an athlete-patient with suspected cervical spine instability.”⁴⁴ This represents a shift from leaving the helmet and shoulder pads in place. For ice hockey players with suspected cervical spine injury, more research is needed on cervical motion during the entire sequence—partial logrolls, spine-boarding, placement of cervical collar before or after logroll, and different immobilization techniques for transport.³⁷

The athlete must be carefully transferred to a spine board with either logroll or lift-and-slide. Although an extrication cervical collar can be placed before the spine board is placed, the effectiveness of this collar in executing the spine-board transfer is not proven.⁴⁵ When the player is on the spine board, the head can be secured with pads and straps en route to the hospital.

Return-to-Play Criteria for Cervical Spine Injuries There is no clear consensus on return-to-play guidelines for cervical spine injuries in athletes.⁴⁶

Shoulder Injuries

For hockey players, the upper extremity traditionally has been considered a well-protected area.⁴⁸ However, shoulder pads are considerably more flexible in hockey than in football and other collision sports. In addition, hockey gloves allow a fair amount of motion for stick handling, and the wrist may be in maximal flexion or extension when a hit against the boards or the ice occurs. Open-ice checking, board collisions, and hockey stick use have been postulated as reasons for the high incidence of upper extremity injuries in hockey. Researchers in Finland found that upper extremity injuries accounted for up to 31% of all hockey injuries.⁴⁹ More than 50% of these injuries resulted from checking or board collisions. Furthermore, study findings highlighted a low rate of injury in younger players and indicated the rate increases with age.^49,50

In hockey players, the acromioclavicular (AC) joint is the most commonly injured shoulder structure.⁵¹ The mechanism of injury can be a board collision or an open-ice hit, but most often is a direct blow to the shoulder. The collision disrupts the AC joint and can sprain or tear the coracoclavicular ligaments. The Rockwood classification is used to categorize AC joint injuries (Figure 2).

Summary

Hockey is a high-speed collision sport with one of the highest injury rates among all sports. Physicians caring for youth, amateur, and senior hockey teams see a range of acute head, neck, and shoulder injuries. Although treatment of eye injuries, dental injuries, and concussions is not always considered orthopedic care, an orthopedic surgeon who is covering hockey needs to be comfortable managing these injuries acutely. Quality rink-side care minimizes the impact of the injury, maximizes the functional result, and expedites the safe return of the injured player back to the ice.

Am J Orthop. 2017;46(3):123-134. Copyright Frontline Medical Communications Inc. 2017. All rights reserved.