Osteochondritis dissecans of the lateral femoral condyle of the knee joint.

Differences in the features of osteochondritis dissecans (OCD) affecting the lateral and medial femoral condyles were investigated in 13 patients (14 knees) treated from 1991 to 1994. OCD affected the lateral femoral condyle in 6 knees (lateral group) and the medial condyle in 8 knees (medial group). The lateral group was younger (mean age, 14 v. 20 years). The radiological stage (Brückl) of the lateral group was stage 2 in 3 knees and stage 3 in 3. The lateral menisci were all discoid and the condylar articular surface of the lesions was normal in two knees, softened in 3 and detached in 1. The medial group comprised 1 knee in stage 2, 1 in stage 3, 1 in stage 4, and 5 in stage 5. The OCD lesion showed softening in 2 knees and detachment in 6. Repetitive abnormal stress on weaker osteochondral structures in the growing period produced by a discoid meniscus during growth may cause OCD of the lateral femoral condyle.