DEVELOPMENT OF THE HIP IN DIASTROPHIC DYSPLASIA

We examined 50 patients with diastrophic dysplasia both clinically and radiologically. Two legally aborted fetuses were dissected. The mean age of the patients was 16.2 years (newborn to 38) and the mean follow -up was 11.4 years (3 months to 34 years). The fetal hips and MRI of n ewborn infants showed congruity and no significant joint deformity. Fl exion contracture of the hip became evident later in 93% and was progr essive. The radiological appearance of the proximal femoral ossific nu clei was delayed and in 17% of males and 28% of females the ossific nu clei had not appeared by the age of 12 years. Radiological measurement s differed considerably from reference values and were related to the rapid and progressive restriction of rotational movement and the incre ase in flexion contracture, The typical findings were flattening and i nferomedial bulking of the femoral head and a double-hump deformation. The changes in the hip led to secondary osteoarthritis before early m iddle age. We describe the clinical and radiological measurements whic h define the early degeneration of the joint.