Magnetic Resonance Imaging Evaluation of the Movement and Morphological Changes of the Menisci during Deep Knee Flexion

Abstract

Accurate in vivo data concerning the movement of the menisci through the full range of motion of the knee joint are lacking. Using a superconductive open-type magnetic resonance (MR) imaging system, we investigated the movement and morphological changes of the menisci during non-weight-bearing deep knee flexion. In 20 healthy adult subjects (mean age, 21.5 years), the knee was moved from 0° to passive maximal flexion (mean angle, 147°), and sagittal images of the knee were taken using a superconductive open-type MR system. In each meniscus, backward movement distance during deep knee flexion and the ratio of anteroposterior internal diameter at deep flexion to that at extension were calculated. For both menisci, the backward excursion of the anterior horn was significantly greater than that of the posterior horn. No difference was significant between the excursion of the anterior horn of the medial meniscus and that of the lateral meniscus during deep knee flexion, but the excursion of the posterior horn of the lateral meniscus was significantly greater than that of the medial meniscus. When the knee was deeply flexed, the anteroposterior diameter of the meniscus was significantly reduced for both the medial and lateral menisci, as compared with the diameter when the knee was extended. In young healthy individuals, the movement and morphological changes of the menisci during deep knee flexion suggest that the menisci might adapt to the environment formed by the combination of the femoral condyles and tibial plateaus throughout the full range of motion.