# The meniscofemoral ligaments do not contribute to restriction of posterior tibial translation: A robotic biomechanical analysis

## TL;DR

This study shows that the meniscofemoral ligaments do not help restrict posterior tibial translation in the knee, while the posterior cruciate ligament is the main stabilizer.

## Contribution

The study provides new biomechanical evidence that the MFLs do not contribute to knee joint stability during posterior tibial translation.

## Key findings

- Neither the aMFL nor the pMFL significantly contributed to restricting posterior tibial translation in any flexion angle.
- The PCL showed a significant and increasing contribution to restraining PTT with increasing knee flexion.
- Cutting the MFLs does not destabilize the knee, suggesting they are not critical for PTT restraint.

## Abstract

The aim of this study was to quantify the contribution of the meniscofemoral ligaments (MFLs) on restraining a posterior tibial translation (PTT) in the human knee joint.

Sixteen human cadaveric knee joints were tested in a robotic test setup with six degrees of freedom. Knees with no MFL, one MFL and two MFLs were included. Knee joints without MFLs were excluded from the statistical analysis regarding the influence of MFLs on PTT. The knees were tested in a displacement‐controlled protocol, which replayed the native kinematics of a force controlled test protocol with PTT at 89 N in neutral tibial rotation, PTT in 5 Nm internal rotation, PTT in 5 Nm external rotation, while constantly measuring the force. The principle of superposition was used to determine the contribution of each cut structure (in‐situ forces) to restraint of the performed movements. First, the anterior and posterior MFL (aMFL/pMFL) were randomly cut, followed by the posterior cruciate ligament (PCL).

Neither the aMFL, nor the pMFL showed a significant contribution to the restriction of PTT in the PCL‐intact knee neither in 0°, 30°, 60° or 90° of flexion in neutral, internal, or external rotation (p > 0.05). The PCL showed a significant contribution to the knee joint restraining PTT in 0°, 30°, 60° and 90° flexion as well as in all rotation states (all p < 0.05). A contribution of the PCL restraining PTT of 28% ± 14% in 0° flexion, 53% ± 21% in 30° flexion, 61% ± 20% in 60° flexion and 54% ± 16% in 90° knee flexion was measured in neutral rotation.

The MFLs do not contribute to restriction of a PTT in any flexion angle, while the PCL acts as the primary restraint against PTT from 0°–90° knee flexion. This effect was seen in neutral rotation as well as in tibial internal and external rotation. This study indicates that a dissection of the MFLs to gain access to the PCL during reconstruction surgery does not destabilise the knee.

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