The hip in hereditary multiple exostoses

We defined the characteristics of dysplasia and coxa valga in hereditary mu ltiple exostoses (HME) by radiological analysis of 24 hips in 12 patients. The degree and effect of the 'osteochondroma load' around the hip were quan tified. We investigated the pathology of the labrum and the incidence of osteoarthr itis and of malignant change in these patients. Coxa valga and dysplasia we re common with a median neck-shaft angle of 156 degrees, a median centre-ed ge angle of 23 degrees and Sharp's acetabular angle of 44 degrees. There wa s overgrowth of the femoral neck with a significantly greater ratio of the neck/shaft diameter in HME than in the control hips (p < 0.05), as well as correlations between the proximal femoral and pelvic osteochondroma load (p < 0.05) and between the proximal femoral osteochondroma load and coxa valg a (p < 0.01). Periacetabular osteochondromas are related to Sharp's angle a s an index of dysplasia (p < 0.05), but not coxa valga. No correlation was found between dysplasia and coxa valga. These data suggest that HME may cause anomalies of the hip as a reflection of a generalised inherited defect, but also support the theory that osteoch ondromas may themselves precipitate some of the characteristic features of HME around the hip.