Progressive subluxation of the hip joint in a child with hereditary multiple exostosis.

We describe the treatment and follow-up of a case of hereditary multiple exostosis in a 16-year-old girl, who had intraarticular and extraarticular osteochondromas in the right hip joint which caused hip subluxation. These osteochondromas were excised, the femoral head was located concentrically, and the patient was put in a spica cast for 6 weeks. Six months later, hip magnetic resonance imaging showed no evidence of avascular necrosis. Three years after the operation the patient walked freely, without pain, and there was satisfying coverage of the femoral head. The authors emphasize that careful attention should be given to the surgical technique prior to extraarticular and intraarticular acetabular osteochondroma excision in order to avoid the development of avascular necrosis.