Summary

This study demonstrated no significant changes in peak contact pressure, contact area, and contact pressure due to ramp lesion and posterior root tear of the medial meniscus. Knee flexion angle is an important role in the contact characteristic change associated with meniscus lesions.

Abstract

Background

Ramp lesion is defined as a longitudinal tear at the meniscocapsular junction or meniscotibial ligament of the posterior horn medial meniscus. The meniscal ramp lesion may contribute to residual anteroposterior instability and affect knee biomechanics. Similarly, the meniscal root lesion, an injury extended to the periphery has been believed to result in the reduction of meniscal hoop stress. The purpose of the study was to analyze the contact characteristic change of the tibiofemoral joint that occurs with an unstable ramp lesion of the medial meniscus

Methods

12 Cadaveric knees (6 matched pairs) were tested under 600 N of axial load with a custom testing jig that allowed positioning of the knee in 0°, 45°, and 90° of flexion without otherwise constraining the knee. Knees were randomly assigned to ramp lesion (n=6) and posterior root lesion (n=6). Four testing conditions were tested: (1) intact, (2) ramp lesion, (3) posterior root tear of the medial meniscus, and (4) combined ramp lesion and posterior root tear of the medial meniscus. Tibiofemoral force transmission, joint contact area, contact pressure, and peak contact pressure were measured with a flexible pressure sensor I-Scan System. Biomechanical testing data were compared for statistically significant differences.

Results

Testing conditions significantly affected the medial tibiofemoral joint's force transmission and contact pressure (P = .04 and P = .036). The contact pressure in the isolated ramp lesion (1.71 ± 0.68 MPa, P = .877) and isolated posterior root tear (2.12 ± 0.92 MPa, P = .069) was non-significantly increased compared to the intact condition (1.77 ± 0.91 MPa). In the combined ramp and posterior root lesion, contact pressure (2.13 ± 0.67 MPa, P = .011) was significantly higher than in the intact condition. The knee flexion position significantly affected the medial tibiofemoral joint's contact area and contact pressure (P < .001 and P < .001).

Conclusions

This study demonstrated no significant changes in force transmission, contact area, and contact pressure in isolated ramp lesions. However, ramp lesion combined with posterior root tear could significantly increase the contact characteristic change in the medial tibiofemoral joint than isolated posterior root tear.