[Isolated or predominant bone cysts of the femoral head].

By definition, the signs of osteoarthritis in this context are absent or minor. Isolated or predominant bone situated anywhere in the femoral head, are more or less well demarcated and occasionally multiple or multilocular. They affect men three times more frequently than women with a mean age of 34 years. Painful disability is generally moderate and intermittent for many years. Limitation of movement is minor or absent. The clinical course is very slow and rarely required surgical treatment. Aetiology: in the 23 cases observed over a period of 20 years, two thirds involved a dysmorphic femoral head: coxa plana, polyepiphyseal dysplasia, osteochondritis dissecans, occasionally associated; three cases were due to excessive pressure (dysplasia or subluxation without signs of osteoarthritis). The other possible causes were juxta-articular bone cyst, chondroblastoma, giant cell tumour and clear cell chondrosarcoma.