BACKGROUND: Repairs of large rotator cuff tears often fail to heal. A possible factor in these failures is excessive tension in the repair sutures, causing them to pull through the tendon. HYPOTHESIS: Arm positions encountered during early rehabilitation after cuff repair can dramatically increase the relative tension in the different sutures of the cuff repair. STUDY DESIGN: Controlled laboratory study. METHODS: In a cadaver model, a 4-suture supraspinatus repair was carried out with transosseous sutures. After the repair, the arm was placed in 12 different positions. The tension in each suture was monitored using individual load cells. RESULTS: When the arm was externally rotated relative to the plane of the scapula, the tension in the anterior suture was over 10 times that in the posterior suture (P < .001). When the arm was internally rotated, the tension in the posterior suture was over 10 times that in the anterior suture (P < .0005). When the arm was in neutral rotation, there was no significant difference in the suture tension. CONCLUSIONS: This study is the first report of direct suture tension measurement after a model rotator cuff repair. In this model, 30 degrees of either internal or external rotation of the arm in relation to the plane of the scapula created substantial imbalances in the tension between the most anterior and most posterior sutures of a supraspinatus repair, regardless of the position of abduction. CLINICAL RELEVANCE: Avoiding external rotation stretching during the healing of supraspinatus repairs may prevent tension overload in the critical anterior suture.
BACKGROUND: Repairs of large rotator cuff tears often fail to heal. A possible factor in these failures is excessive tension in the repair sutures, causing them to pull through the tendon. HYPOTHESIS: Arm positions encountered during early rehabilitation after cuff repair can dramatically increase the relative tension in the different sutures of the cuff repair. STUDY DESIGN: Controlled laboratory study. METHODS: In a cadaver model, a 4-suture supraspinatus repair was carried out with transosseous sutures. After the repair, the arm was placed in 12 different positions. The tension in each suture was monitored using individual load cells. RESULTS: When the arm was externally rotated relative to the plane of the scapula, the tension in the anterior suture was over 10 times that in the posterior suture (P < .001). When the arm was internally rotated, the tension in the posterior suture was over 10 times that in the anterior suture (P < .0005). When the arm was in neutral rotation, there was no significant difference in the suture tension. CONCLUSIONS: This study is the first report of direct suture tension measurement after a model rotator cuff repair. In this model, 30 degrees of either internal or external rotation of the arm in relation to the plane of the scapula created substantial imbalances in the tension between the most anterior and most posterior sutures of a supraspinatus repair, regardless of the position of abduction. CLINICAL RELEVANCE: Avoiding external rotation stretching during the healing of supraspinatus repairs may prevent tension overload in the critical anterior suture.