Abstract
Purpose:
Biomechanical knowledge of the medial collateral ligament (MCL) is important for MCL release during knee arthroplasty. The purpose of this study was to define the influences of the deep medial collateral ligament (dMCL) and the posterior oblique ligament (POL) on valgus and rotatory stability in knee arthroplasty.
Methods:
Six cadaveric knees were divided into 2 groups with unique sequential sectioning sequences of the dMCL and the POL. Group A (n = 2) first received femoral arthroplasty only, and thereafter sequentially received medial half tibial resection with spacer, ACL cut, dMCL cut, POL cut, and finally tibial arthroplasty. Group B (n = 4) first received femoral arthroplasty only, and thereafter sequentially received medial half tibial resection with spacer, ACL cut, tibial arthroplasty, dMCL cut, and finally, POL cut. A CT-free navigation system monitored motion after application of valgus loads (10 N-m) and internal and external rotation torques (5 N-m) at 0°, 20°, 30°, 60°, and 90°of knee flexion.
Results:
There were no significant differences in medial gaps under valgus loads after cutting dMCL, but significant differences were seen in medial gaps after cutting POL. Internal rotation angles increased after cutting POL under internal rotation torques at over 20°of knee flexion. External rotation angles under external rotation torques increased after cutting dMCL at 90°. In addition, external rotation angles further increased after cutting POL.
Accordingly, while increases of medial gap size and rotatory instability were not clearly recognized with the sectioning of the dMCL, significant increases of valgus and rotatory instability were seen on sectioning of the POL.
