Higher critical shoulder angle increases the risk of retear after rotator cuff repair

Background: No evaluation has been done on the relationship of the critical shoulder angle (CSA) with retear after rotator cuff repair. Our purpose was to evaluate whether a higher CSA is associated with retear after rotator cuff repair. Methods: This was a retrospective review of 76 patients who had undergone rotator cuff repair with postoperative ultrasound examination. Ultrasound findings were graded no retear (NT), partial-thickness (PT) retear, or full-thickness (FT) retear. Preoperative radiographs were used to measure CSA, glenoid inclination, lateral acromion angle, and acromion index. Results: Average age was 61.9 years (45.3-74.9 years). On ultrasound examination, 57 shoulders (74.0%) had NT, 11 (14.2%) had PT retears, and 8 (10.3%) had FT retears. There was no significant difference in retear rate by age, gender, or tension of repair. Average CSA was significantly lower for the NT group at 34.3 degrees +/- 2.9 degrees than for the FT group at 38.6 degrees +/- 3.5 degrees (P <.01). If CSA was >38 degrees, the odds ratio of having an FT retear was 14.8 (P < .01). In addition, higher CSA inversely correlated with postoperative American Shoulder and Elbow Surgeons scores (P < .03). Average glenoid inclination was significantly lower in the NT group at 12.3 degrees +/- 2.7 degrees compared with 17.3 degrees +/- 2.6 degrees in the FT group (P < .01). If glenoid inclination was > 14, the odds ratio of having a FT retear was 15.0 (P < .01). Conclusion: At short-term follow-up, higher CSA significantly increased the risk of an FT retear after rotator cuff repair. Also, increasing CSA correlated with worse postoperative American Shoulder and Elbow Surgeons scores. This radiographic marker may help manage expectations for rotator cuff tear patients. (C) 2017 Journal of Shoulder and Elbow Surgery Board of Trustees. All rights reserved.