Biomechanical effect of patch graft for large rotator cuff tears: a cadaver study

It is not possible for some rotator cuff tears to be repaired because of a large defect associated with muscle retraction. The purpose of the current study was to investigate the use of a synthetic patch graft to restore abduction force transmission in the glenohumeral joint with a rotator cuff defect. Shoulders from cadavers (n = 10) were fixed in the hanging arm and in neutral rotation, and loading was applied to the rotator cuff tendons and middle deltoid. After a simulated supraspinatus tendon defect and retraction, a patch graft was inserted into the defect and the effects of reattachment to the greater tuberosity, narrowing of the defect by using a smaller graft, and anterior graft attachment (rotator interval tissue versus subscapularis) were investigated. Abduction torque generation was measured and normalized to the intact condition. Compared with torque generation after creation of a supraspinatus defect (61% of normal torque), abduction torque increased with a graft between the infraspinatus and either the rotator interval (68% of normal) or subscapularis (80% of normal). The optimum grafting technique for abduction torque restoration occurred with a reduced size patch connected anteriorly to the subscapularis and sutured to the greater tuberosity (107% of normal). The patch graft acts to redirect force transmission, thereby providing a potential treatment option for otherwise irreparable defects. These same principles can be applied when tendon transfers are used to reconstruct large or massive cuff tears.