Anatomic Knot Suture Anchor Versus Knotless Suture Anchor Technique for Anterior Talofibular Ligament Repair: A Biomechanical Comparison.

Background: To date, there are few biomechanical studies comparing the strength between knot repair and knotless repair procedures for anterior talofibular ligament (ATFL) injury. Purpose: To perform a biomechanical comparison of the strength of the arthroscopic ATFL repair technique with knot or knotless suture anchors in a cadaveric model with partial or complete ATFL injuries. Study Design: Controlled laboratory study. Methods: A total of 24 fresh-frozen cadaveric ankles were used. Arthroscopy was used to identify, section, and repair the ATFL on the fibular insertion site. The specimens were then randomly placed into 1 of 4 groups: group A received complete ATFL section and 1-suture anchor repair with knot, group B received complete ATFL section and 1-anchor knotless repair, group C received partial ATFL section and 1-suture anchor repair with knot, and group D received partial ATFL section and 1-anchor knotless repair. After repair, the ATFL tension was measured first with a digitalized tensiometer. Specimens were then mounted on a materials testing system to determine the ultimate load to failure and stiffness. Results: The mean +/- SD ligament tension measured during the arthroscopic procedure was 8.6 +/- 0.6 N for group A, 9.2 +/- 0.5 N for group B, 9.4 +/- 1.1 N for group C, and 9.6 +/- 0.9 N for group D. No significant difference in tension was detected among groups. In load-to-failure testing, the mean ultimate failure load was 27.9 +/- 4.1 N for group A, 26.2 +/- 9.3 N for group B, 81.9 +/- 26.5 N for group C, and 88.1 +/- 41.6 N for group D. The mean ultimate failure loads of the partial repair groups were significantly higher than those of the complete repair groups (C vs A, P = .008; D vs B, P = .002), while there was no significant difference between groups A and B (P > .05) or between groups C and D (P > .05). Conclusion: The results of the present study showed that there was no significant difference in biomechanical properties between knot repair and knotless repair techniques.