PURPOSE: Maximizing the strength of flexor tendon repair techniques allows earlier postoperative rehabilitation and improved functional results. The tensile strength of currently used repair techniques is defined by the force required for suture pullout or knot rupture. Use of a barbed suture for flexor tenorrhaphy could overcome these limitations, permitting knotless repair with tendon barb adherence along the suture's entire length. The purpose of this study is to evaluate the tensile strength of a novel technique for flexor tendon repair employing barbed suture.
METHOD: Thirty-eight cadaveric FDP tendons were lacerated in Zone II and randomized to a novel barbed 2-0 polypropylene repair in a knotless 3-strand or 6-strand configuration, or to a traditional 4-strand cruciate repair with either 4-0 polypropylene, 4-0 braided polyester, or 4-0 fiberwire. For each repair, we recorded the cross-sectional area at the repair site before and after tenorrhaphy. Tendons were linearly distracted to failure, and load at failure and mode of failure recorded. One-way ANOVA and chi-squared tests were used to determine significant differences between groups.
RESULTS: The mean cross-sectional area ratio of 4-strand cruciate control repairs was 1.5 +/- 0.3, whereas those of 3-core and 6-core barbed repairs were 1.2 +/- 0.2 (p = 0.009) and 1.2 +/- 0.1 (p = 0.005), respectively. The mean load to failure of control repairs was 29 +/- 7N, whereas those of 3-core and 6-core barbed repairs were 36 +/- 7N (p = 0.32) and 88 +/- 4N (p < 0.001), respectively. Cruciate repairs failed by knot rupture or pullout in 24/24 tendons whereas barbed repairs failed by suture breakage in 13/14 repairs (p < 0.001).
CONCLUSION: In an ex-vivo model of flexor tendon repair, a 3-core barbed suture technique achieved tensile strength comparable to that of traditional 4-core cruciate repairs, while demonstrating significantly less repair site bunching. A 6-core barbed suture technique demonstrated markedly increased tensile strength compared to 4-core cruciate controls, as well as significantly less repair site bunching. Our data suggest that barbed suture repair may offer several advantages in flexor tenorrhaphy, and that further in-vivo testing is warranted.