The tension required at repair to reappose the supraspinatus tendon to bone rapidly increases after injury.

Rotator cuff tears occur frequently and can cause significant pain and reduced shoulder function. A high percentage of patients are satisfied after surgical repair of rotator cuff tears, but a smaller percentage of patients with chronic tears continue to have pain and poor shoulder function. This may be partly attributable to an increase in the repair tension, the force required at repair to reappose the tendon to its original insertion site on the humerus. Increases in repair tension have been shown to occur for long-standing ruptures of the supraspinatus tendon, but the precise tension at various times after injury are unknown. Therefore, the objective of the current study was to determine the repair tension at various times after a rotator cuff tear. This was achieved by creating a full-thickness supraspinatus tendon tear in a rat model and measuring the mechanical characteristics of the musculotendinous unit at 0, 2, 4, 9, and 16 weeks after injury. The repair tension rapidly increased initially after injury followed by a progressive, but less dramatic, increase with additional time. These findings suggest that rotator cuff tears should be repaired early in the clinical setting. Future studies will investigate the effect of repair tension on tendon to bone healing after repair.