Comparison of 4 Different 4-Strand Core Suturing Techniques for Flexor Tendon Laceration: An Ex Vivo Biomechanical Study

Background: Forces applied to the repaired flexor tendon should not exceed its yield force during early postoperative rehabilitation to prevent gapping and rupture. We aimed to biomechanically compare the tensile strengths and the 2-mm gapping of 4 different 4-strand core suturing techniques for flexor tendon repair.

Methods: Fifty-six goat deep digital flexor tendons were repaired with the 4-strand double-modified Kessler, the 4-strand augmented Becker, the 4-strand Savage, and the 4-strand modified Tang techniques. All tendons were repaired with 4-0 polyester for core suture and 5-0 polyester for continuous epitendinous running suture. The specimens were subjected to static linear tensile testing by applying a single linear load-to-failure pull. After the linear load testing, the yield load, the ultimate strength of the repaired tendons, and the force exerted to yield a 2-mm gap were measured.

Results: All peripheral sutures ruptured near the yield point. All core suture techniques were similar regarding the yield force. The augmented Becker 4-strand technique had the greatest ultimate strength (98.7 [82-125.3] N). The modified double Kessler technique was the weakest in resisting a 2-mm gap formation. The 4-strand modified Tang repair had the shortest (11.3 [7-15] minutes), while the 4-strand augmented Becker had the longest operative time (29 [23-33] minutes).

Conclusions: All 4 techniques demonstrated similar yield force, with differences in operative time, ultimate strength, and resistance to gapping. Future clinical studies can further elucidate their appropriateness for early active motion protocols.