Comparative biomechanical performances of 4-strand core suture repairs for zone II flexor tendon lacerations.

To compare the biomechanical performances of six 4-strand flexor tendon repairs at zone II, we used an in situ testing model in 54 cadaver profundus tendons. The techniques studied were the modified Becker, modified double Tsuge, Lee, locked cruciate, Robertson, and Strickland. Prerepair and postrepair comparisons for work of flexion to a 3.9-N pulp pinch (equal to 12.6 N tendon force) showed the greatest interference to gliding in the modified Becker repair and the least in the modified double Tsuge repair. Mean gaps after 1,000 load-unload cycles to a 3.9-N pulp pinch did not approach the clinically important limit of 3 mm in all groups. Ultimate tensile strength was highest in the modified Becker (69.4 +/- 8.2 N) but not significantly higher than the modified double Tsuge (60.3 +/-15.3 N) and locked cruciate (64.1 +/- 16.2 N). In all repair groups the mean pulp pinch forces upon failure were well above values recommended for active mobilization protocols that use external load guides. The locked cruciate, modified double Tsuge, and modified Becker repairs were strong enough for an early active motion protocol after surgery. Locked cruciate and modified double Tsuge were easier to perform and provided less interference to tendon gliding than the modified Becker repair.