Osteochondral lesion

What the term covers

Osteo means bone and chondral means cartilage. The term covers a range: a bruised but intact area, a fragment that is cracked but still attached, a loose fragment, or a crater where the fragment has come out completely and may float in the joint as a loose body.

Common sites are the femoral condyles and, after a kneecap dislocation, the underside of the patella or the outer edge of the femur.

Why it matters

Because bone is involved, the lesion affects the support beneath the cartilage. An unstable fragment can catch or lock the knee and cause repeated swelling. Left alone, a large lesion in a weight-bearing area may lead to early arthritis.

In children and teenagers with open growth plates, stable lesions often heal with rest. In adults, healing is less predictable.

How it is assessed and treated

MRI shows the size, whether fluid tracks under the fragment, which suggests instability, and the state of the bone. A CT scan is sometimes added. Stable lesions may be treated with activity limits. Unstable but healthy fragments can often be fixed back with screws or pins. Where the fragment is lost or damaged, cartilage restoration techniques fill the defect.