MR assessment of movement and morphologic change in the menisci during knee flexion

PURPOSE: To examine movement and morphologic alteration in the menisci during knee flexion. MATERIAL AND METHODS: Twenty healthy knees were imaged at 0 degrees, 45 degrees, and 90 degrees of passive non-weight-bearing flexion in the sagittal plane with MR. In each meniscus, posterior movement distance during knee flexion and the ratio of anteroposterior (a.p.) diameter at flexion to that at extension were calculated. RESULTS: Each meniscus moved posteriorly during knee flexion. Movement was greater in the anterior horn than in the posterior horn, and greater in the medial meniscus than in the lateral meniscus (p<0.05). The a.p. diameter of each meniscus was reduced at flexion (p<0.05). CONCLUSION: Knee flexion normally leads to posterior movement and shortening of the a.p. diameter of the menisci, which may be related to the positioning and curvature of femoral condyles at the femorotibial contact point at knee flexion.