Biomechanical study comparing three different methods of 'double-row suture-bridge' rotator cuff repair

Abstract

Rotator cuff repair using double-row suture-bridge configuration was statistically stronger than other repair methods. It is a common practice to tie two mattress sutures on each of the medial row anchor. However, failure usually occurred by pulling out of tendon from the suture, leading to catastrophic damage to the tendon. To reduce the possible strangulation effect, some surgeons tied only one mattress suture on medial row anchor. However, it was not known whether this reduced strength of the construct. It was also not known whether there is difference in mode of failure of the repair. Methodology: To answer these questions, a biomechanical study on pig infraspinatus tendon repair model comparing classic “Double-row suture-bridge with double mattress on each medial row anchor” (Suture A) with two repair methods with tying of only one mattress suture on medial row, “Double-row suture-bridge with single mattress on each medial row anchor” (Suture B) and “Double-row suture-bridge with modified Mason Allen suture” (Suture C) were performed. 60 fresh pig shoulders were harvested. Infraspinatus tendon was dissected from the footrpint and repaired back using either one of the three repair methods. The specimen was loaded to failure on a Material Testing System. The ultimate load to failure and the pattern of failure were recorded. The integrity of tendon at the repair site was noted. Result: 60 pig shoulders were tested (20 Suture A, 20 Suture B and 20 Suture C). The average ultimate load to failure was 437 +/- 94 N. Suture B was stronger than Suture A and Suture C (p<0.001). The average load to failure for Suture B was 498 +/- 82 N while that of Suture A was 444 +/- 78 N and Suture C was 372 +/- 79 N. The tendon was grossly intact after load to failure in Suture C repair (70%); in contrast that tendon was severely destroyed in both Suture A (67%) and Suture B (75%) repair methods (p<0.001). Conclusion: Tying two mattress sutures on the same medial row anchor (Suture A repair) did not increase the mechanical strength of the repair construct, when comparing with tying one mattress sutures (Suture B repair). Suture C repair (“Double-row suture-bridge with modified Mason Allen suture”) can be considered as the most “revision-friendly” repair method as it minimized damage to the tendon substance during load-to-failure biomechanical testing.