Hereditary multiple exostoses of the hip.

PURPOSE To assess the radiographic features of 36 hips with hereditary multiple exostoses (HME). METHODS Hip parameters of 12 males and 6 females (36 hips) aged 2 to 28 years with HME were assessed using anteroposterior radiographs. The recorded features included the sites of osteochondromas, the femoral head/neck ratio, the Reimer's migration percentage, Sharp's acetabular angle, the centre edge angle, the femoral neck-shaft angle, and degenerative changes. RESULTS 15 of the 18 patients were asymptomatic; 3 complained of pain (2 underwent excision or bone biopsy); no lesion was malignant. Osteochondromas were most commonly located in the femur followed by the ilium; only one was intra-articular. 32 hips had coxa valga; 26 had an abnormal Reimer's migration percentage; 17 had an abnormal Sharp's acetabular angle; 12 had an abnormal centre edge angle; 32 had an abnormal femoral neck-shaft angle; and 6 had degenerative changes. Acetabular and femoral dysplasia as well as subluxation are common in patients with HME. CONCLUSION Borderline subluxated hips and those with marked coxa valga and/or acetabular dysplasia should be closely monitored to determine the need for surgery in the future. Subluxated hips should be operated on early, particularly in children and symptomatic adults.