Summary

This study determines the role of the lateral menisco-tibial ligament in the phenomenon of meniscal extrusion and analyzes the biomechanical consequences of its repair as well as the capsulodesis technique.

Abstract

Introduction. Previous studies have hypothesized that the lateral menisco-tibial ligament and the recently described Menisco-Tibio-Popliteus-Fibular Complex act together as a restrictor of the radial mobility of the lateral meniscus. The capsulodesis technique was described in 2017 as a quick and cheap solution to reduce meniscal extrusion after lateral meniscal allograft transplantation with satisfactory results at two and seven years of follow-up. The purpose of this study was to determine the function of the lateral menisco-tibial ligament in terms of radial mobility of the lateral meniscus as well as load distribution on the lateral tibial plateau and to determine if its repair as well as the capsulodesis technique restore this mobility and load to their native values in a biomechanical model using human cadaveric knees.

Methods. Eleven human, fresh-frozen cadaveric knees were used for testing in this study. Prior authorization of an ethics committee. A diagnostic arthroscopy, simple radiographs and an MRI were performed to include healthy knees without high degrees of joint wear or associated ligamentous injuries. The lateral menisci were circumferentially implanted with radiopaque spherical markers. They were mounted to a testing apparatus applying muscle and ground-reaction forces. The meniscus was evaluated at 0, 30, 90, and 120 grades of knee flexion using Roentgen stereophotogrammetric analysis (RSA) and with a second method using two markers put on the posterior cruciate ligament and the lateral meniscus, and the load distribution were assessed using a pressure mapping sensor system after applying a loading force of 200 N to the knee joint. Measurements were recorded for 4 states: the native lateral meniscus, the injury of the lateral meniscus-tibial ligament, the primary repair of the mentioned ligament, the injury of the lateral meniscus-tibial ligament without repair but performing the arthroscopic technique of capsulodesis. Both cyclic loading and load-to-failure testing were performed. The displacement, stiffness, response to cyclic loading, and mode of failure were recorded and analyzed statistically.

Results. The maximum values of extrusion occurred at 60 degrees of flexion, during biomechanical testing, the mean absolute meniscal extrusion at baseline was 1.3 ± 0.5 mm. After creation of the meniscotibial ligament lesion, the mean absolute meniscal extrusion was significantly increased (3.7 ± 0.9 mm) (P< 0.001). After repair, the extrusion was reduced to 1.8 ± 0.4 mm and after the capsulodesis the extrusion was reduced to 2.0± 0.5 mm. There were no statistically significant differences between the results of these last two groups. The average contact pressure of the tibial cartilage was significantly higher in the injury group than in the intact group or the primary repair and capsulodesis group.

Conclusions. This study indicates that the lateral menisco-tibial ligament contributes to meniscal stability restricting the radial mobility of the lateral meniscus as lesions cause the meniscus to extrude and that repair of these ligaments and the capsulodesis technique can significantly reduce extrusion.