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Spontaneous osteonecrosis of the knee

Case contributed by Natalie Yang
Diagnosis almost certain

Patient Data

Age: 65 years
Gender: Male

Oval radiolucency with central sclerosis in the subchondral medial femoral condyle. 

Spontaneous osteonecrosis of the knee (SONK) involving the weight-bearing portion of the medial femoral condyle, with associated articular surface impaction fracture. Maceration and degenerative tears of the body and posterior horn of the medial meniscus is associated with meniscal extrusion and osteophytic lipping. Incidental Bakers cyst.

Case Discussion

Spontaneous osteonecrosis of the knee (SONK) of the lateral aspect of the medial condyle (most common location). 

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