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.