Biomechanical Study of Asymmetric Flexor Tendon Repair Using a 6-Strand 4-0 Supramid Suture Versus a 4-Strand 2-0 Tenoflex Suture

Abstract

Background: Multi-strand repair of flexor tendons are important for increased strength but this may cause ischemia during the intrinsic healing process. In this study, we aim to compare the strength of the 4-strand modified Asymmetric repair using 2-0 Tenoflex® suture with the original description of the Asymmetric repair using a 6-strand 4-0 Supramid® suture under cyclic loading in a porcine tendon model. We hypothesise that the number of core sutures through the repair site can be reduced with advanced suture material. Methods: Two groups consisting of 10 porcine tendons each were repaired using the Asymmetric repair technique. One group underwent the original description using a 6-strand 4-0 Supramid® suture and the other group underwent a modified 4-strand technique using 2-0 Tenoflex® suture. The repaired tendons were subjected to a two-stage cyclic loading test. Survival rate and gap formation at the repaired site were analysed. The failure mechanism of each repair was also analysed. Additionally, the cross-sectional area of each strand of core suture used was also calculated. Results: The 1st and 2nd stage survival rates were 90% and 30% for the 6-strand repair and 100% and 60% for the 4-strand repair respectively. The mean gap formation at the end of stage 2 was 1.79 mm (SD 1.57) for the 4-strand repair, which is comparable to that of the 6-strand repair (1.82 mm; [SD 1.20]). The total mean cross-sectional area of 2-0 Tenoflex® and 4-0 Supramid® suture strands were 0.078 and 0.086 mm2, respectively. Conclusions: These results demonstrate that despite having fewer core sutures, the 4-strand modified Asymmetric repair using 2-0 Tenoflex® may be a better option as compared to the original 6-strand Asymmetric repair using 4-0 Supramid®.