Abstract
Introduction
Many factors can influence post-operative kinematics after total knee arthroplasty (TKA). These factors include intraoperative surgical conditions such as ligament release or quantity of bone resection as well as differences in implant design. Release of the medial collateral ligament (MCL) is commonly performed to allow correction of varus knee. Precise biomechanical knowledge of the individual components of the MCL is critical for proper MCL release during TKA. The purpose of this study was to define the influences of the deep medial collateral ligament (dMCL) and the posterior oblique ligament (POL) on kinematics in TKA.
Materials and Methods
This study used six fresh-frozen cadaveric knees with intact cruciate ligaments. All TKA procedures were performed by the same surgeon using CR-TKA with a CT-free navigation system. Each knee was tested at 0°, 20°, 30°, 60°, and 90° of flexion. One sequential sectioning sequence was performed on each knee, beginning with femoral arthroplasty only (S1), and thereafter sequentially; medial half tibial resection with spacer (S2), ACL cut (S3), tibial arthroplasty (S4), release of the dMCL (S5), and finally, release of the POL (S6). The same examiner applied all external loads of 10 N-m valgus and 5 N-m internal and external rotation torques at each flexion angle and for each cut state. The AP locations of medial and lateral condyles were determined as the lowest point on each femoral condyle. All data were analyzed statistically using paired t-test. A significant difference was determined to be present for P < .05.
Results
All knees showed that posterior femoral translation of the lateral condyle from 0° to 90° was greater than posterior femoral translation of the medial condyle at any step or any tested angle. Posterior femoral translation of the medial femoral condyle under valgus load significantly increased after S4 compared with that at S1 at 20°, 30° and 90°, and after S5 compared with that at S1 at 20° and 30°. Thereafter, significant increase in posterior translation of the medial condyle was seen, at 30° after S6 compared with S1. Posterior femoral translation of the medial femoral condyle under external rotation torque significantly increased after S4 at 90°, and S6 at 0° compared with that at S1. Posterior femoral translation of the medial femoral condyle under internal rotation torque significantly increased after S2 at 0°, after S4 at 60° and 90°, after S5 at 0°, and after S6 at 60° compared with S1.
Conclusion
From this study we concluded that retaining of the medial knee structures preserves the valgus and rotatory stability of the knee after TKA. Accordingly, to devise a surgical approach of retaining the dMCL and POL has a possibility to improve outcomes after primary TKA.
