A Knotless Flexor Tendon Repair Technique Using a Bidirectional Barbed Suture

Flexor tendon repairs using conventional suture require knots that enlarge the cross-sectional area at the repair site.1,2 This enlargement increases the force of finger flexion and jeopardizes the integrity of a nascent tendon repair during early active motion rehabilitation.3-5 We hypothesize that a knotless flexor tendon repair using a bidirectional barbed suture has similar strength with reduced cross-sectional area when compared to traditional flexor tendon repairs. Sixty-six fresh porcine flexor digitorum profundus (FDP) tendons were randomly divided into three groups of 22, labeled A, B, and C. Tendons were transected and repaired as follows: group A, two-strand modified Kessler technique; group B, four-strand Savage technique; group C, four-strand knotless technique. Prior to transection and after repair, the cross-sectional area of each tendon was calculated at the repair site, one centimeter proximal, and one centimeter distal to the repair site. All tendons underwent mechanical testing to assess the 2mm gap-formation force, ultimate strength, and mode of failure. The 2mm gap-formation force, ultimate strength, and cross-sectional area at the repair site were as follows: group A (Kessler) 23N, 32N, 24.4mm2, group B (Savage) 59N, 69N, 31.9mm2, and group C (knotless) 62N, 72N, 32.3mm2. Both the 2mm gap-formation force and ultimate strength of groups B and C were significantly greater than those of group A (p< 0.0001); however, groups B and C did not significantly differ. The repair site cross-sectional area of group C was significantly less than that of groups A and B (p<0.00005). We demonstrate that knotless flexor tendon repair with barbed suture has equivalent strength with reduced repair site cross-sectional area compared to traditional techniques. A knotless flexor tendon repair offers many potential advantages over traditional repairs. Decreased repair site cross-sectional area may reduce the work of flexion and lower the risk for post-surgical tendon rupture, allowing for more aggressive rehabilitation after flexor tendon repair. References 1. Aoki M, Manske PR, Pruitt DL, Larson BJ. Work of flexion after tendon repair with various suture methods: A human cadaveric study. J Hand Surg. 1995 June;20(3):310–13. 2. Momose T, Amadio PC, Zhao C, Zobitz ME, An KN. The effect of knot location, suture material, and suture size on the gliding resistance of flexor tendons. J Biomed Mater Res. 2000;53(6):806-11. 3. Barrie KA, Tomak SL, Cholewicki J, Merrell GA, Wolfe SW. Effect of suture locking and suture caliber on fatigue strength of flexor tendon repairs. J Hand Surg [Am]. 2001 Mar;26(2):340-6. 4. Tang JB, Cao Y, Xie RG. Effects of tension direction on strength of tendon repair. J Hand Surg [Am]. 2001 Nov;26(6):1105-10. 5. Zhao C, Amadio PC, Momose T, Couvreur P, Zobitz ME, An KN. The effect of suture technique on adhesion formation after flexor tendon repair for partial lacerations in a canine model. J Trauma. 2001 Nov;51(5):917-21.