Summary

The hypothesis was that the lateral meniscus has its own dedicated surface on the tibial plateau its disruption leads to the reduction of the LM's support in turn resulting in progression of degenerative changes of the meniscus as well as articular surface

Abstract

Objective

Identification of disruptions in the congruency of the lateral meniscus (LM)' setting on the tibial plateau in case of patients with the anterior cruciate ligament (ACL) injury combined with the damage to the posterior margin of the tibia is important due to the meniscus’ role in knee biomechanics. The reduction of the meniscus’ support affecting its normal movement is a potential source of accelerated progression of degenerative changes of the meniscus and tibial plateau. The aim of the study was to establish the proper setting of the lateral meniscus on the plateau and estimate possible outcomes of the disruption of LM’s movement.
Materials and Methods
The MRI scans of control group including 10 healthy volunteers and the study group comprised of 10 pain-free ACL patients with a damage to the posterior margin of the tibia were compared since a proper MRI examination of the lateral meniscus in full knee flexion is limited in case of patients with mild to severe knee pain.  All subjects had MRI scans done in maximum knee flexion (sagittal plane, PD, using the GE 3.0T Discovery device). In all cases the position and setting of the meniscus against the articular surface were determined.

Results

The control group’s MRIs confirmed the lateral meniscus slope onto the “dedicated” surface of the posterior margin of the tibia, which was assumed by the authors based on the literature review and own observations combined with clinical experience. The study group’s images have also confirmed the incorrect setting of the lateral meniscus and its deformation in the maximal knee flexion recorded in cases when the compression fracture of the posterior tibial plateau’s surface led to the significant reduction of the support required for the proper movement of the lateral meniscus.

Conclusions

The lateral meniscus glides on its dedicated articular surface on the tibial plateau and the absence of the congruence between the LM and its dedicated slope appears to be a likely source of accelerated degeneration of both meniscus and the adjoining articular surface of the tibia in patients with prior ACL injury. The results gathered so far should be considered preliminary findings and require further validation on a larger group and done in different conditions allowing the assessment of the meniscus’' movement at more angles.