Superior capsule reconstruction to restore superior stability in irreparable rotator cuff tears: a biomechanical cadaveric study.

BACKGROUND: There have been many clinical reports of patch graft surgery for irreparable rotator cuff tears. However, the retear rate of the patch graft is relatively high because of the lack of superior stability, causing subacromial abrasions.

PURPOSE: To compare superior stability among 3 types of patch grafting for simulated irreparable rotator cuff tears.

STUDY DESIGN: Controlled laboratory study.

METHODS: Eight cadaveric shoulders were tested in a custom shoulder testing system. Superior translation of the humerus, subacromial contact pressure, and glenohumeral joint force were quantified in the following 5 conditions: (1) when the rotator cuff was intact, (2) after cutting the supraspinatus tendon, (3) after the patch graft to reconstruct the supraspinatus tendon, (4) after the patch graft to reconstruct the superior capsule, and (5) after the patch graft to reconstruct both the supraspinatus tendon and superior capsule. While the graft was sutured to the torn tendon in condition 3, the graft was attached to the superior glenoid in condition 4.

RESULTS: Compared with values for intact rotator cuffs, cutting the supraspinatus tendon significantly increased superior translation (P < .05), significantly increased subacromial contact pressure (P < .05), and significantly decreased glenohumeral compression force (P < .05). Superior translation was restored partially after the supraspinatus tendon patch graft and restored fully after the superior capsule patch graft and after both patch grafts. All patch grafts fully restored the subacromial contact pressure (P < .05) but did not alter the glenohumeral joint force.

CONCLUSION: When patch graft surgery is chosen for irreparable rotator cuff tears, the graft should be attached medially to the superior glenoid and laterally to the greater tuberosity to restore superior stability of the humeral head.

CLINICAL RELEVANCE: The superior capsule patch graft completely restored superior stability of the glenohumeral joint, while patch grafting to the supraspinatus tendon partially restored superior translation.