Summary

Following arthroscopic rotator cuff repair, decreased external rotation strength and external rotation range of motion was significantly more likely in individuals who sustained traumatic rotator cuff tears with concurrent shoulder dislocation than those who sustained traumatic rotator cuff tears alone.

Abstract

Introduction

For patients with traumatic rotator cuff tears following acute shoulder dislocation, arthroscopic rotator cuff repair has been shown to restore stability and improve patient outcomes including pain relief, increased function, decreased recurrence, and increased patient satisfaction. What is not known is how outcomes differ between patients with traumatic tendon ruptures and shoulder dislocation against those with traumatic tendon ruptures without dislocation.

Methods

Patients with arthroscopic rotator cuff repairs performed between 2013-2017 were included. The first cohort (Dislocation & Tear Cohort) included all patients with acute dislocations and concurrent traumatic rotator cuff tears. These patients were matched 1:2 with a second cohort of patients who sustained traumatic rotator cuff tears without dislocations (Tear Only Cohort). Matches were based on age, sex, smoking status, BMI, arm dominance relative to injury, and functional co-morbidity index. These cohorts were compared at the most recent follow-up on record. Continuous variables were compared with either the Wilcoxon rank sum test or the two-sample t-test and categorical variables were compared with the chi-square or Fisher’s exact test.

Results

Among 720 cuff tears reviewed, 226 exhibited tears traumatic in etiology. Fourteen of these traumatic cuff tears resulted from a shoulder dislocation and these patients were placed in the Dislocation & Tear Cohort (n=14). Patients with traumatic rotator cuff tears and no dislocation were selected based on match criteria and placed in the Tear Only Cohort (n=28). After comparing the two groups, Dislocation & Tear Cohort exhibited a mean age of 58.7 ±11.3 years, BMI of 32.4 ± 5.9, and Functional Comorbidity Index of 1.4±1.0. The Tear Only Cohort exhibited a mean age of 58.9 ± 11.2 years, BMI of 30.1 ± 5.2, and Functional Co-Morbidity Index of 1.8 ± 1.6. There were no significant differences between the two groups in the mean age (p=.96), BMI (p=.20), or functional comorbidity index (p=.74). Both groups were 64% male and included 7% current tobacco users. Patients sustaining a concurrent shoulder dislocation were more likely to present with infraspinatus involvement than patients with tears alone (p=0.001). The concurrent dislocation group also displayed a larger mean tear size (29.6 ± 13.3 mm) than the tear only group (15.8 ± 7.5 mm) (p=.01). The Dislocation and Tear Cohort’s median final follow up was 8.8 months following surgery while the Tear Only Cohort’s median final follow up was 9.4 months after surgery. Outcomes at final follow up showed external rotation strength was less likely to be 5/5 in the Dislocation & Tear Cohort than the Tear Only Cohort (p=.01). Additionally, external rotation range of motion was worse in patients with concurrent dislocations (39.6 ± 12.8°) than those with tears only (48.2 ± 7.8°) (p=.02).

Conclusions

Following arthroscopic rotator cuff repair, decreased external rotation strength and range of motion was significantly more likely in individuals who sustained traumatic rotator cuff tears with concurrent shoulder dislocation than those who sustained traumatic rotator cuff tears alone. This difference is likely related to a higher incidence of infraspinatus involvement and larger tear size following the injury.