Radiology of the pelvis and hips in adults with Down's syndrome.

In a radiological study of the pelvis in 66 adult subjects with Down's syndrome, 25 (38%) were found to have the classical pelvic sharpe associated with Down's syndrome in infancy and childhood. The appearance of the pelvis and hip joints was very variable and matched the variety of appearances seen in normal subjects, except that generally the pelvis was smaller than normal. The discriminating value of the iliac index (which is abnormal in up to 80% of affected infants) was lost in this group of affected adults. Subluxation and osteoarthrosis of the hips were very uncommon features. In addition to the primary morphological abnormalities in the pelvis in Down's syndrome that are described in the literature, posture probably plays a part in producing the variable radiological appearances of the pelvis.