Osteochondral lesion

Linear hypodensity

Lytic lesion on the right medial femoral condyle.

Osseous fragment

Osteochondritis dissecans

Bone deformity

A 15 mm osseous fragment close to the lytic lesion is compatible with a detached fragment from a type 4 osteochondritis dissecans.

Intra-articular swelling

Linear hypodensity

A small anterior joint effusion can be seen on the lateral view.