Passive tension and gap formation of rotator cuff repairs.

The objectives of this study were to quantify the relationship between passive tension of rotator cuff repairs and arm position and to examine the effect of this tension on repair gap formation. Five patients undergoing open surgical rotator cuff repair of the supraspinatus tendon were recruited. Tendon tension was recorded as the supraspinatus was advanced into a bone trough and secured. The relationship between arm position and repair tension was then measured. Standardized rotator cuff tears were created in 3 cadaveric shoulders and repaired by use of the intraoperative technique. The difference in tension measured between 0 degrees and 30 degrees abduction was statically applied for 24 hours and the gap formation measured. Repair tension increased with advancement of the supraspinatus tendon into the bone trough. Abduction reduced the repair load. The mean reduction in load by 30 degrees abduction was 34 N. Twenty-four hours of 34-N loading caused gap formation of 9 mm in cadaveric rotator cuff repairs. Passive tension in surgically repaired rotator cuffs may contribute to repair failure and can be modified by arm positioning.