Suture anchor repair of soft tissue structures has become more popular. Internal bracing is a new augmentation method using suture tape. Medial collateral ligament (MCL) injury is one of the most common injuries of the knee joint and residual valgus laxity might affect the healing of repair, especially in the setting of simultaneous anterior cruciate ligament (ACL) reconstruction. Internal bracing may provide an additional means of stabilization. MCL repair with internal bracing has shown promising clinical results. However, there are currently no biomechanical studies showing the effectiveness of internal bracing at resisting valgus load to the knee. The aim of this study was to test the biomechanical effects of MCL repair with internal bracing in the setting of a concomitant ACL reconstruction.
15 fresh frozen human cadaveric knees were tested using a six-degrees-of-freedom robotic system under four loadings: (a) an 89.0-N anterior tibial load, (b) a 5.0-Nm internal and external rotation torque, (c) a 10.0-Nm valgus load, (d) a 7.0-Nm valgus load combined with 5.0-Nm internal rotation torque as a simulated pivot-shift. The tested conditions were (1) ACLR/MCL intact, (2) ACLR/MCL deficient, (3) ACLR/MCL repair, (4) ACLR/MCL repair augmented with suture tape.
For combined ACL reconstruction and MCL repair, for valgus displacement suture tape augmentation did better than suture repair alone and 15 and 30 degrees of knee flexion. The suture tape restored external rotation to the intact state and all knee flexion angles, whereas suture repair only did not. Internal bracing did not cause over-constraint in any of the tested loading conditions.
In a combined ACL reconstruction MCL repair model, augmentation with suture tape had a positive effect on knee kinematics during valgus and external rotation as compared to suture repair alone. This study provides evidence to support the use of internal bracing in conjunction with MCL repair in the setting of a concomitant ACL reconstruction.