Radiographic knee dimensions in discoid lateral meniscus: Comparison with normal control

We reviewed the knee radiographs of 68 cases of arthroscopically proven discoid lateral meniscus, including 42 cases of complete type and 26 cases of incomplete type discoid lateral meniscus. Knee radiographs of 70 cases that had no arthroscopic evidence of pathology of the meniscus were used as controls. We excluded patients who had significant trauma history and who were under 16 years of age or over 60 years to avoid measuring radiographs of skeletally immature or degenerative knees. The absolute values and relative normalized values of specific knee dimensions, such as a squared-off appearance of the lateral femoral condyle, widened femorotibial joint space, cupping of the lateral tibial plateau, obliquity of the lateral tibial plateau articular surface, high fibular head, and hypoplasia of the lateral intercondylar spine, were compared between the patients with discoid lateral meniscus and the normal controls. Among those dimensions, high fibular head and widened lateral tibiofemoral joint space showed statistically significant differences between the discoid lateral meniscus group and normal control group. We suggest that these findings would be useful in screening lateral discoid meniscus on plain radiography.