Suture number determines strength of rotator cuff repair.

Failure of surgical repair of a rotator cuff tear continues to be a clinical problem. For other tendon repairs, increasing the number of sutures improves both biomechanical performance and clinical outcomes. Several investigators have shown biomechanical advantages of double-row techniques but have used many more sutures than were used with the single-row techniques with which the double-row techniques were compared. The purposes of our study were to establish whether using a greater number of sutures would improve the biomechanical properties of a rotator cuff repair model, and whether using equal numbers of sutures would lead to equivalent results between single and double-row configurations.Fresh-frozen sheep infraspinatus tendons underwent single-row repair with two, four, or six mattress sutures and double-row repair with use of four mattress sutures. Specimens were pretensioned at 10 N for one minute, then cycled from 10 to 180 N for 200 cycles at 0.2 Hz; this was followed by load to failure. Cyclic gap formation, failure load, and failure type were recorded.The four-suture single-row and four-suture double-row repairs had similar gap formation during cyclic testing, with no significant differences between them. Cyclic gap formation in the two-suture single-row group was 6.7 and 7.1 mm (97% and 109%) greater than that in the four and six-suture single-row groups after 200 cycles (p < 0.001). The average loads to failure of the two, four, and six-suture single-row groups were 274, 362, and 572 N (p < 0.0001). The average load to failure of the four-suture double-row group was 386 N, which was similar to the value in the four-suture single-row group (p = 0.58).In an ovine rotator cuff tendon repair model, increasing the number of sutures decreased cyclic gap formation and increased load to failure. Single and double-row repairs are biomechanically equivalent when the number of sutures is kept constant.The results of this study support the use of greater numbers of sutures in rotator cuff repair and disagree with the assertion that double-row repairs are biomechanically superior to single-row repairs.