Summary

The meniscofemoral ligaments do not contribute to the knee resisting a posterior tibial translation if the posterior cruciate ligament is intact.

Abstract

Introduction

The meniscofemoral ligaments (MFLs) attach the lateral meniscus to the medial femoral condyle and are divided into an anterior and a posterior MFL (aMFL / pMFL). In addition to the meniscus-stabilizing function, the MFLs are hypothesized to function as secondary restraints to posterior tibial translation (PTT). The aim of this study was to investigate the influence of the MFLs on restriction of a PTT.

Methods

16 human cadaveric knee joints were tested in a validated robotic test setup with 6 degrees of freedom. First, the kinematics of the native knee joint were determined, using a force-controlled test protocol. For this, the following test protocol was carried out at 0, 30, 60 and 90°: PTT with 89 N in neutral tibial rotation, PTT in 5 Nm internal tibial rotation, PTT in 5 Nm external tibial rotation. The native knee motions were then transferred to a discplacement-controlled test protocol, which repeating the native knee movements, measured the forces. Subsequently, if present, aMFL and pMFL were cut in randomized order. Finally, the PCL was sectioned, to compare the influence of the MFLs against the PCL. Using the principle of superposition the percentage reduction in force compared to the native state after each cutting step could be determined, corresponding to the contribution of each cut structure in restriction of a PTT. Statistical analysis was carried out with PRISM (Graphpad Software) using mixed-linear models.

Results

In all flexion and rotation conditions, the PCL was found to be the primary stabilizer against a PTT (p < 0.05). In neutral rotation, a contribution of 28 ± 14 % in 0° extension, of 53 ± 21 % in 30° flexion, of 61 ± 20 % in 60° flexion and 54 ± 16 % in 90° knee was found for the PCL. In internal and external rotation, in all tested flexion angles, the PCL was found to be the primary restraint to PTT as well (p < 0.05). Neither the aMFL, nor pMFL was found to be a significant contribution to the restriction of PTT in neutral, internal or external tibial rotation (p < 0.05).

Conclusion

The present study demonstrated no significant involvement of the MFLs in stabilizing the knee joint against PTT. Conversely, the PCL acted as the primary stabilizer of the knee joint in neutral, internal and external tibial rotation from 0° - 90° knee flexion, in this study. It can therefore be concluded that the MFLs have no relevant effect on the stabilization of the PCL-intact, or PCL-reconstructed knee joint.