Anterior capsulolabral lesions combined with supraspinatus tendon tears: biomechanical effects of the pathologic condition and repair in human cadaveric shoulders.

PURPOSE

Our purpose was to investigate the effect of supraspinatus tendon tear combined with anterior capsulolabral injury on glenohumeral joint biomechanics and to identify which structures should be repaired when both pathologic conditions are present.

METHODS

Eight cadaveric shoulders were tested on a custom system. Five conditions were tested: intact supraspinatus full-thickness tear, supraspinatus tear combined with Bankart lesion, supraspinatus repair, and supraspinatus repair combined with Bankart repair. Rotational range of motion, glenohumeral kinematics, and the force required for anteroinferior dislocation were measured at 30° and 60° of glenohumeral abduction. Repeated-measures analysis of variance with Tukey post hoc test was used for statistical analysis.

RESULTS

Bankart lesions combined with supraspinatus tears significantly increased total rotational range of motion (7.6° ± 6.3° at 30° of glenohumeral abduction and 14.1° ± 10.3° at 60° of glenohumeral abduction; P < .05). Bankart lesions combined with supraspinatus tears also significantly decreased the force required for dislocation normalized to range of motion (26.6% ± 21.0% at 60° of abduction) compared with intact shoulders (P = .04). Bankart repair combined with supraspinatus repair restored range of motion and the force required for dislocation; however, Bankart repair combined with supraspinatus repair shifted the humeral head posteriorly at the midrange of rotation in 30° and 60° of abduction (P < .05).

CONCLUSIONS

Supraspinatus tendon tears combined with Bankart lesions increased humeral rotational range of motion and decreased the force required for dislocation. Repair of both pathologic conditions successfully restored range of motion and increased the force required for dislocation.

CLINICAL RELEVANCE

Both supraspinatus tendon and anterior labral repair are suggested for patients with combined Bankart lesions and supraspinatus tears to restore shoulder function and possibly prevent recurrent dislocation. However, when repairing both pathologic conditions, care should be taken not to overtighten the joint, which may lead to stiffness or osteoarthritis.