Rotator cuff tear incidence association with critical shoulder angle and subacromial osteophytes

The concomitant presence of a heel-type osteophyte may affect the critical shoulder angle (CSA) correlation with rotator cuff tears (RCT).

We retrospectively reviewed patients with and without a full-thickness RCT who underwent magnetic resonance imaging (MRI) and radiographic imaging of the shoulder. The patients were divided into 3 groups according to the CSA as high CSA group, >38°; middle CSA group, 33°-38°; and low CSA group, <33°. We confirmed the presence of heel-type osteophytes, quadrangular osteophytes protruding inferiorly from the undersurface of the anterolateral acromion like the heel of a shoe, and excluded other types of osteophytes.

Among the patients, 84.6% in the high CSA group, 60.3% in the middle CSA group, and 68.3% in the low CSA group had a RCT (P = .041). In patients without an osteophyte, 76.9% in the high CSA group, 38.5% in the middle CSA group, and 52.6% in the low CSA group had a RCT (P = .024). In patients with an osteophyte, 92.3% in the high CSA group, 80.3% in the middle CSA group, and 92.2% in the low CSA group had a RCT (P = .106).

RCT was affected more by osteophytes than CSA when CSA and osteophytes were evaluated together as a related factor for RCT. This perhaps suggests no correlation of CSA alone with RCT. Therefore, the presence of an osteophyte must be considered when evaluating the relation of CSA to RCT.