Subchondral insufficiency fracture - knee

Case contributed by Domenico Nicoletti
Diagnosis certain


Pain without trauma.

Patient Data

Age: 70 years
Gender: Female

Sclerosis of the medial tibial plate with reduction of the joint space of the same side.

Extensive bone marrow edema and subchondral bone collapse on both femoral and tibial surface medial compartment.

Magnetic resonance imaging reveals extensive bone marrow edema and subchondral bone collapse on the medial compartment of the femoral and tibial surface where grade 4 chondral loss is present.

There is also a voluminous Baker cyst.

Case Discussion

Subchondral insufficiency fractures are non-traumatic fractures that occur immediately below the cartilage of a joint. Patients with subchondral insufficiency fracture characteristically have unremarkable plain radiographs, while MRI examination may reveal extensive bone marrow edema and subchondral bone collapse. Subchondral insufficiency fractures of the knee is also known as spontaneous osteonecrosis of the knee (SONK). 

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