Presentation
Follow-up x-ray of a known knee problem.
Patient Data
There is flattening and irregularity of the weight-bearing surface of the lateral femoral condyle, consistent with osteochondritis dissecans of the knee. There is subchondral sclerosis, and a lucent area suggesting subchondral cyst formation. X-rays of the other knee (not shown) demonstrated similar changes.
Case Discussion
Osteochondritis dissecans typically affects the lateral surface of the medial femoral condyle in adolescent males. The weight-bearing surfaces of the lateral femoral condyle, tibia or patella may also be involved. Spontaneous healing is usual unless there is an unstable fragment. Signs of instability include large size (>1 cm), cyst-like lesions beneath a fragment, contrast beneath a fragment on contrast arthrography, and loose body. Osteochondritis dissecans may be bilateral in 20-25% of cases.
The differential diagnosis includes normal fusing apophysis (painless) or acute osteochondral fracture. In older patients, there may be insufficiency fracture or spontaneous osteonecrosis of the knee (SONK).
Unable to process the form. Check for errors and try again.