Spontaneous Osteonecrosis of the Knee

Abstract

The authors experienced three cases of spontaneous osteonecrosis of the knee reported by S. Ahlbäck in 1968. This lesion is characterized by the radiolucent area with circumscribed sclerosis in the medial femoral condyle and by sudden onset with persisting pain in the knee.
Case 1 was 66-year-old woman who had sudden onset of persisting pain of the knee and has been treated as osteoarthritis, X-ray showed slight flattening of the medial femoral condyle two months after onset. When she admitted at 8 months after onset, complaining of severe deteriolated pain, it was revealed that the flattened area progressed to radiolucent area contained a thin calcified plate which was sorrounded by a sclerotic halo. The treatment was made by splinting and complete non-weight-bearing for two months with marked recovery of clinical symptome and x-ray finding examined 1 year and 4 months after onset,
Other 2 cases, 78-year-old man and 77-year-old woman, were reported briefly,