Biomechanical comparison of fixation techniques for medial collateral ligament anatomical augmented repair

Abstract

Purpose: Although the majority of medial collateral ligament (MCL) ruptures can be treated conservatively with good results, some injuries require operative treatment. Besides MCL reconstruction, anatomical augmented repair may be considered. This study was to assess biomechanical properties of different fixation techniques regarding elongation and ultimate load to failure.

Methods: MCL anatomical augmented repair was simulated by fixation of porcine superficial digital flexor tendon grafts at porcine tibiae. Ten different fixation techniques were assessed. Fixation of the tendon graft was performed using 4.0-mm cancellous screws and either (1) 13.5-mm spiked polyether ketone (PEEK) washers; (2) 14-mm spiked washers; (3) 14-mm suture washers; (4) 14-mm customized washers; (5-8) combination of washers and No. 2 polyester sutures (FiberWire©); or using (9) single or (10) double 5.5-mm titanium suture anchors with No. 2 polyethylene sutures (Ultrabraid^®). Biomechanical analysis included pretensioning of the constructs at 20 N for 30 s following cyclic loading of 250 cycles between 20 and 100 N at 1 Hz for measurement of elongation. Additionally, ultimate failure load and failure mode analysis were performed.

Results: Spiked PEEK washers secured with polyester sutures (5) yielded best biomechanical properties at time zero for both, elongation during cyclic loading (2.9 ± 0.7 mm) and ultimate failure load (469.8 ± 64.3 N).

Conclusions: These results suggest that spiked PEEK washers secured with polyester sutures are the most appropriate fixation technique for MCL anatomical augmented repair, thus providing best requirements to allow early knee mobilization and prevent secondary knee laxity.

Keywords: Biomechanics; Knee; Medial collateral ligament; Polyester sutures; Suture anchors; Washer.