Higher Critical Shoulder Angle and Acromion Index Are Associated With Increased Retear Risk After Isolated Supraspinatus Tendon Repair at Short-Term Follow Up

Purpose: To evaluate the effect of critical shoulder angle (CSA), acromion index (AI), and glenoid inclination (GI) on the postoperative healing rate after arthroscopic supraspinatus tendon repair. Methods: Patients after arthroscopic repair of a symptomatic, unilateral, single-tendon, full-thickness supraspinatus tear in whom nonoperative management had failed were retrospectively reviewed. Magnetic resonance imaging (MRI) studies were obtained 6 months postoperatively and were evaluated by 2 independent observers. Repair integrity was classified as either intact or torn. Preoperative true anteroposterior radiographs were used to measure CSA, AI, and GI. Results: Fifty-seven patients were evaluated 6 months postoperatively. The mean patient age at surgery was 54.7 ± 7.7 years. On MRI studies, 41 patients (71.9%) had an intact repair and 16 patients (28.1%) had a full-thickness retear. There were no significant differences between the intact and retear group in regard to patient age (P =.648), initial tear size (P =.205), or fatty degeneration (P =.508). The mean CSA for the retear group (37° ± 4°) was significantly higher than that in the intact group (35° ± 3°; P =.014). If the CSA was >38° the odds ratio of having a retear was 3.78 (95% confidence interval 1.05 to 13.58; P =.042). Average AI for the retear group (0.73 ± 0.09) was significantly higher than that in the intact group (0.69 ± 0.06; P =.049). The mean GI was 17° ± 6° for the intact group and 16° ± 6° for the retear group (P =.739). Conclusions: At short-term follow-up, higher CSA and AI significantly increased the retear risk after arthroscopic supraspinatus tendon repair. CSA >38° increased the retear risk almost 4-fold. Overall GI was elevated but did not correlate with failure rate. Level of Evidence: III, case control study.