Characteristic shape of the lateral femoral condyle in patients with osteochondritis dissecans accompanied by a discoid lateral meniscus.

BACKGROUND There are various indirect signs of a discoid lateral meniscus in radiographs, for example lateral joint space widening, hypoplasia of the LFC, etc. There has, however, been no previous report of the characteristic shape of the lateral femoral condyle (LFC) in patients with osteochondritis dissecans (OCD) accompanied by a discoid lateral meniscus. The purpose of this study was to evaluate the characteristic shape of the LFC in patients with OCD accompanied by a discoid lateral meniscus, and sex differences associated with the shape of the LFC in those patients. METHODS This study included 29 males (31 knees) and 29 females (32 knees) of average age 17.7 years. There were 15 knees in 15 patients that were accompanied by OCD of the LFC (9 males, 9 knees; 6 females, 6 knees; average age 14.9 years; OCD group). There were 48 knees in 43 patients that were not accompanied by OCD of the LFC (20 males, 22 knees; 23 females, 26 knees; average age 17.6 years; non-OCD group). Standardized Rosenberg view radiographs of the knee were obtained for all patients. We evaluated the shape of LFC using the Rosenberg view and measured the condylar prominence ratio of the medial and lateral condyles adjacent to the intercondylar notch, in accordance with Ha's procedure. RESULTS The OCD group had a significantly larger prominence ratio than the non-OCD group. The prominence ratio for males was significantly larger than that for females. CONCLUSION We clearly demonstrated that the prominence ratio in the OCD group was significantly larger than that in the non-OCD group, indicating that the shape of the LFC and OCD in the LFC may be associated with the development of these lesions.