A Biomechanical Assessment of Repair Versus Nonrepair of Sheep Flexor Tendons Lacerated to 75 Percent

Purpose The benefit of repairing a 75% partial flexor tendon laceration remains controversial. The purpose of this study was to assess the degree of gap formation with and without repair when the 75% lacerated tendon is subjected to cyclic loading. Repair with only a peripheral suture was compared to that using a core and peripheral repair technique. Methods Sixteen deep flexor tendons from sheep hind limbs were lacerated to 75% of the tendon diameter. The cut tendons were loaded for 100 cycles from 3 N up to 30 N and then back to 3 N, at a rate of 0.2 Hz. Gap formation was measured at 0 and 100 cycles. Tendons were then randomized into 2 repair groups of 8 each: group 1 was repaired with only a simple, running peripheral suture (6-0 polypropylene monofilament), whereas group 2 was repaired with a modified Kessler core suture (4-0 silicone-coated braided polyester) plus a peripheral suture (6-0 polypropylene monofilament). Repaired tendons were tested for 500 cycles, and the gap was measured at 0, 100, and 500 cycles. After cycling, gap was measured at 100 N load, and the peak loads were determined on static failure testing. Results The 75% partially lacerated tendons had >2 mm gap at 100 cycles. This gap was significantly reduced by peripheral or peripheral plus core repairs (p < .001). There was no difference in gap formation between tendons with peripheral repair only and those with both peripheral and core repairs. Gap formation in repaired tendons remained <= 1 mm at 500 cycles. After cycling, neither gap formation at 100 N load or the peak loads on failure testing differed between the 2 repair groups. Conclusions There is a large gap when an unrepaired 75% partial laceration is cyclically loaded. This gap is significantly reduced with a peripheral repair whether or not a core suture is used. (J Hand Surg 2010;35A:546-551. (C) 2010 Published by Elsevier Inc. on behalf of the American Society for Surgery of the Hand.