A knotless suture anchor construct in MCL reconstruction is not inferior to traditional fixation methods

Objectives: Traditionally, most medial collateral ligament (MCL) injuries have been managed non-operatively. Recent studies, however, have questioned this approach, highlighting the biomechanical and clinical consequences of residual medial laxities. This in turn has led to a widening in the indications for MCL reconstruction. The distal attachment of the superficial medial collateral ligament is located on the subcutaneous border of the proximal tibia approximately 6 cm distal to the joint line, in close proximity to the insertion of the hamstring tendons. Traditional fixation methods, such as staples and soft-tissue washers, are bulky and may irritate these tendons, necessitating implant removal. A novel fixation technique utilizing knotless suture anchors offers the potential advantages of a broad attachment area, with low-profile fixation. The aim of this study was to evaluate the biomechanical performance of a novel knotless suture anchor construct for tibial sided MCL reconstruction fixation. The null hypothesis is that there is no difference between the new technique when compared to traditional methods. Methods: Distal MCL reconstruction fixation was performed in 24 human proximal tibial specimens using peroneus longus tendon grafts. Specimens were randomized to one of three fixation methods: spiked ligament staple, screw and soft-tissue washer, and the study technique utilizing 4 knotless suture anchors. After fixation the specimens were mounted in an instrom machine and the graft was subjected to a 50N longitudinal force for 1000 cycles followed by load to failure. Elongation under cyclic loading, peak force at failure, and macroscopic mode of failure were recorded. Results: There was no significant difference in elongation (1.05 mm ±0.6 in the staple group, 0.63 mm ±1.2 in the screw and washer group, and 1.09 mm ±0.7 in the knotless suture anchor group) or median maximum load to failure (132.11 N ±40.2 for the knotless suture anchor group, followed by the staple group 123.89 N ±64.1 (95% CI) and the screw and washer group 120.75 N ±54.9) between the groups. The mode of failure was tendon pullout at the tibial fixation site in all specimens. Conclusion: The novel knotless suture anchor technique showed biomechanical outcomes comparable to traditional fixation methods. While there are potential advantages to this technique, including low profile fixation and a lesser need for implant removal, further clinical studies are required to determine its role in MCL surgery.