<i>In Vivo</i> biomechanical evaluations of suture anchors for repairing grade 3 superficial medial collateral ligament injury in a porcine model.

Abstract

To clarify the biomechanical and radiological outcomes of superficial medial collateral ligament (sMCL) repair using suture anchors in a large animal model. The right sMCLs of nine male castrated pigs was completely detached at the femoral attachment. sMCL repair surgery was performed using two suture anchors. The same skin incision, sMCL exposure, and immediate wound closure were made at the left knee as a sham surgery. Magnetic resonance imaging was performed preoperatively and 4 weeks after surgery. The structural properties (upper yield load, maximum load, linear stiffness, and elongation at failure) of the femur-sMCL-tibia complex were determined. During tensile testing, all the repaired sMCLs avulsed from the femoral attachment. There were no significant differences in the upper yield load, maximum load, linear stiffness, or elongation at failure between the groups 4 weeks after surgery or in the MRI-derived signal-to-noise quotients (SNQs) at the mid and tibial sMCL. The SNQs differed significantly at the femoral (2.7 ± 1.2 vs 0.3 ± 0.7; <i>P</i> = 0.00064) portions between groups. The injured sMCLs biomechanically recovered after surgery using suture anchors even though the SNQs were higher than those with native contralateral sMCLs. For clinical relevance, sMCL repair of grade 3 sMCL injuries using suture anchors was both safe and successful with less tissue dissection.