osteochondritis dissecans knee LSBU

Description: Radiology case 451-442
Clinical presentation: 13 year old male with pain in the knees. There are almost symmetrical defects of the articular surfaces on the medial side of the lateral condyles of both femora. On the left side the separated bone remains close to its site of origin. In the right knee, the fragment has moved and may be responsible for the ill-defined intra-articular densities, projected between the lateral conyles of right femur and tibia. The endosteal margin is better defined on the right side and this may reflect its greater exposure to intra-articular pressure changes or the density may be due to creeping substitution of newbone over old.