2015 ISAKOS Biennial Congress ePoster #2420

Biomechanical Study Comparing Three Different Methods of "Double-Row Suture-Bridge" Rotator Cuff Repair

Wai Pan Yau, MBBS, FRCS, FHKCOS, FHKAM, Hong Kong HONG KONG
The University of Hong Kong, Hong Kong, HONG KONG

FDA Status Cleared

Summary: The ultimate load to failure in a pig infraspinatus repair model was highest in “Double row suture bridge with one mattress suture on each medial row anchor” (498 +/- 82 N, range = 347 - 609 N) when compared with classic “Double row suture bridge with double mattress on each medial row anchor” (444 +/- 78 N) and “Double row suture bridge with modified Mason Allen suture” (372 +/- 79 N)(p<0.001).

Abstract:

Introduction

Rotator cuff repair using double-row transosseous-equivalent suture-bridge configuration was stronger than other repair methods. It is a common practice to tie two mattress sutures on each of the medial row anchor (Suture A). However, failure usually occurred by pulling out of tendon from the suture, leading to catastrophic damage to the tendon (“cheese-wiring”). It was believed that strangulation effect on the tendon when two mattress sutures were tied on the same anchor point led to increased tendon damage. This made revision surgery difficult because of loss of reparable tendon tissue.

To reduce the possible strangulation effect, some surgeons tied only one mattress suture on each of the medial row anchor. However, it was not known whether this practice reduced biomechanical strength of the construct. It was also not known whether there was less “cheese-wiring” of the tendon when the repair was loaded to failure.

To answer these questions, a biomechanical study on pig infraspinatus tendon repair model comparing the 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 D) were performed.

It was hypothesized that there was no difference in the ultimate load to failure between tying two mattress-suture versus tying one mattress-suture in double-row suture-bridge repair. It was further hypothesized that there was less “cheese-wiring” of tendon in the group which have only one mattress suture.

Methodology

60 fresh pig shoulders were harvested. Infraspinatus tendon was dissected from the footrpint and repaired back using either one of the three repair methods (Suture A, Suture B and Suture C) using double-row suture-bridge method. A total of four double loaded titanium suture anchors (Smith and Nephrew TwinFix 5.0) were used for each repair (2 as medial row and 2 as lateral row). The specimen was loaded to failure on a Material Testing System. The ultimate load to failure and the integrity of tendon at the repair site were recorded.

Result:

60 pig shoulders were tested (20 Suture A, 20 Suture B and 20 Suture D). The average ultimate load to failure was 437 +/- 94 N.

Suture B was stronger than Suture A and Suture D (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 D was 372 +/- 79 N.

The tendon was grossly intact after load to failure in Suture D repair (70%); in contrast that tendon was severely destroyed in both Suture A (33%) and Suture B (25%) repair methods (p<0.001).

Conclusion

Tying two mattress sutures on the same medial row anchor did not increase the mechanical strength of the repair construct. The ultimate load to failure was highest in specimen receiving Suture B repair (498 +/- 82 N, range = 347 to 609 N).