Early versus late repair of rotator cuff tears in rats

Background: In the event of a traumatic rotator cuff tear, patients are routinely advised that early surgical intervention produces an optimal repair, despite a lack of direct evidence to support this recommendation. To address this knowledge gap, massive rotator cuff tears in rats were assessed by biomechanical and bone morphometric analyses after early or late repair. Methods: Combined supraspinatus and infraspinatus tendon tears of the left shoulder were created in 21 adult Wistar rats, which were divided into 2 groups. The tendons of the injured shoulder in the animals in group I were surgically repaired 8 weeks after the injury. Under the same anesthesia, the same injury was created on the right shoulder, which was immediately repaired. The rats from group I were euthanized 8 weeks after the repairs. No repair was performed in the rats from group II, which were euthanized 8 weeks after the injury. Tissues from both groups were harvested and biomechanically tested for supraspinatus tendon and bone morphometry analysis of the humeral head. Results: All biomechanical properties were significantly increased in the early repair group compared with the late repair group. No significant differences were observed in bone morphometry of the humeral head when early and late repair groups were compared. Conclusion: Early surgical repair of a massive rotator cuff tear leads to improved biomechanical properties of the tissue after healing. Proximal humerus bone morphometry was unaffected by surgical repair timing. (C) 2017 Journal of Shoulder and Elbow Surgery Board of Trustees. All rights reserved.