Anterior Cable Reconstruction of the Superior Capsule Using Semitendinosus Allograft for Large Rotator Cuff Defects Limits Superior Migration and Subacromial Contact Without Inhibiting Range of Motion: A Biomechanical Analysis

Abstract

To biomechanically assess translation, contact pressures, and range of motion for anterior cable reconstruction (ACR) using hamstring allograft for large to massive rotator cuff tears. Eight cadaveric shoulders (mean age, 68 years) were tested with a custom testing system. Range of motion (ROM), superior translation of the humeral head, and subacromial contact pressure were measured at 0°, 30°, 60°, and 90° of external rotation (ER) with 0°, 20°, and 40° of glenohumeral abduction. Three conditions were tested: intact, stage III tear (supraspinatus+ anterior half of infraspinatus), and stage III tear+ allograft ACR (involving 2 supraglenoid anchors for semitendinosus tendon allograft fixation. Allograft ACR included loop-around fixation using 3 side-to-side sutures and an anchor at the articular margin to restore capsular anatomy along the anterior edge of the cuff defect. ACR with allograft for stage III tears showed significantly higher total ROM compared with intact at all angles (P ≤ .028). Augmentation significantly decreased superior translation for stage III tears at 0°, 30°, and 60° ER for both 0° and 20° abduction, and at 0° and 30° ER for 40° abduction (P ≤ .043). Augmentation for stage III tears significantly reduced overall subacromial contact pressure at 30° ER with 0° and 40° abduction, and at 60° ER with 0° and 20° abduction (P ≤ .016). Anterior cable reconstruction using cord-like allograft semitendinosus tendon can biomechanically improve superior migration and subacromial contact pressure (primarily in the lower combined abduction and rotation positions), without limiting range of motion for large rotator cuff tendon defects or tears. In patients with superior glenohumeral instability, using hamstring allograft for ACR may improve rotator cuff tendon defect longevity by providing basic static ligamentous support to the dynamic tendon while helping to limit superior migration, without restricting glenohumeral kinematics.