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

Abstract

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. 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 6months 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. Fifty-seven patients were evaluated 6months postoperatively. The mean patient age at surgery was 54.7 ± 7.7years. 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). 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. III, case control study.