Biomechanical Study of Asymmetric Flexor Tendon Repair Using 3 Different Suture Materials

Background: The asymmetric technique for flexor tendon repairs has various advantages but further improvement is possible by using a suitable suture material. In this study, we compare the biomechanical performance of asymmetric repairs using 3 suture materials: Supramid Extra II 4-0, Tendo-Loop 4-0, and FiberLoop 4-0. Methods: We divided 30 porcine flexor tendons into 3 arms. Each arm of tendons were repaired by using 1 of the 3 proposed suture materials. Each repaired tendon was tested by using a mechanical tester. Ultimate tensile strength (UTS), load to 2 mm gap force, failure mechanism and stiffness of the tendons were investigated. Results: FiberLoop® achieved the highest UTS (90.4 ± 17.9 N), followed by Tendo-Loop (85.3 ± 10.3 N). The difference was no statistically significant. The UTS of repairs using Supramid® was significantly lower (64.0 ± 8.4 N). For load to 2 mm gap force, FiberLoop® achieved 20.7 ± 4.8 N while Tendo-Loop® had 20.5 ± 4.2 N. The difference was also no statistically significant. The repairs using Supramid® had a significantly lower load to 2 mm gap force of 14.2 ± 2.7 N. The stiffness of asymmetric repairs using FiberLoop® and Tendo-Loop® was 5.64 ± 1.7 N/mm and 5.63 ± 0.7 N/mm. The difference was also no statistically significant. The repairs using Supramid® had a significantly lower stiffness of 4.15 ± 1.0 N/mm. Failure mechanisms for the repaired specimens were reported as such: Supramid had 100% suture rupture; Tendo-Loop had 90% suture rupture and 10% suture pullout; FiberLoop had 20% suture rupture and 80% suture pullout. Conclusions: The asymmetric repair configuration is able to produce superior biomechanical performance by using Tendo-Loop® or FiberLoop®. Improvement of the asymmetric technique by using Tendo-Loop® or FiberLoop® could potentially contribute to better surgical outcomes of flexor tendon repair.