Abstract
Medial tibial plateau osteonecrosis is a disease that lacks distinguishing signs and symptoms, especially in the early stage, and requires clinicians to exercise a high degree of suspicion to prevent disease progression. We present a case of spontaneous osteonecrosis of the medial tibial plateau in a 59-year-old woman. Within 5 months of the onset of symptoms, the entire medial tibial plateau collapsed down into the metaphyseal region, causing severe varus deformity, instability, and inability to walk without crutches and a hinged knee brace. Initial symptoms of medial joint line pain and generalised swelling of the knee were attributed to early degenerative changes. Subsequent radiographs were misinterpreted as simple medial compartment arthritis. Due to severe bone loss and significant lateral collateral ligament attenuation, a total joint arthroplasty was required, using a stemmed tibial component with medial metal block and bone graft augmentation. The speed of bone collapse and the extension into the metaphysis, requiring complex joint arthroplasty, makes this case unique.