The condition is usually characterized by a sudden onset of<unk>  pain, worse at night, or during weight-bearing such as standing or running. Nevertheless, it can also occur during rest or without any weight-bearing. About 94% of the cases affect the medial condyle of the femur. This is because the blood supply for the medial condyle is less than the blood supply for the lateral condyle of the femur. The condition may deteriorate, causing asymmetrical walking or running pattern. Sometimes, they have a history of osteoporosis or osteopenia. Localised tenderness over the medial<unk>  is the most common finding of the condition. It is usually happening on one side, without a previous history of trauma. SONK should be considered together with differential diagnosis of osteoarthritis, tear of medial meniscus, and tibial plateau fracture. SONK usually has a sudden onset of<unk>  pain, while osteoarthritis has a progressive, gradual onset of<unk>  pain.
Spontaneous osteonecrosis of the knee
Facet joint arthrosis
Osteoradionecrosis
Post-traumatic arthritis
Calcific bursitis
Retrocalcaneal bursitis
Osteochondritis
Transient synovitis