Osteochondritis dissecans of the lateral femoral condyle in the adult.

In osteochondritis dissecans, 15% of the lesions occur in the lateral condyle. In order to understand the significance of these lesions, 27 were studied prospectively from 1983 to 1990 and compared with 20 consecutive cases of lesions of the medial femoral condyle. Lesions of the lateral femoral condyle were larger, and often comprised the entire width of a condyle and resulted in deformation of a significant segment of the femoral condyle. They lay further posteriorly and commonly were associated with mechanical symptoms including buckling or locking. A discernible clunk was unique to these lesions. In addition, lateral lesions were more fragile, often having multiple bony islands that were prone to fragmentation, making replacement difficult if not impossible. Lateral lesions occurred directly within the main force-bearing areas of the condyle, disrupting normal contact areas and possibly leading to more rapid joint deterioration once segments are lost. This has prompted concern for reinsertion of articular fragments or reconstruction with osteochondral allografts.