Biomechanical analysis of the cruciate four-strand flexor tendon repair

The purpose of this study was to develop and test in vitro a new flexor tendon suture technique that was simple and easy to perform, yet strong enough to withstand the projected forces of an in vivo active motion rehabilitation protocol. Forty human cadaveric flexor digitorum profundus tendons were divided and repaired using 1 of 4 suture techniques (the modified Kessler, the Strickland, the modified 4-strand Savage, and the Cruciate 4-strand repairs). Each repair was tested using a slow-test machine and displacement control at 2 mm/s. Force applied, the resultant gap, and ultimate tensile strength were recorded and statistical comparisons were performed using a two-tailed Student's t-test with level of significance set at p = .05. The Cruciate suture technique was demonstrated to be nearly twice as strong to 2-mm gap formation (44 N) compared with the Kessler, Strickland, and Savage repairs. Ultimate tensile strength was also significantly stronger for the Cruciate technique (56 N) than the Kessler, Strickland, or Savage repairs. The technique was significantly faster to perform than the Savage or Strickland repairs and was comparable in repair time to the 2-stranded Kessler repair. The design of the new suture technique allowed the tendon repair to be completed with the ease and speed of a 2-strand technique, but bestowed on the repair strength that exceeded current 4-strand techniques.