SECONDARY AVASCULAR NECROSIS AFTER TREATMENT FOR CONGENITAL DISLOCATION OF THE HIP

We made a radiographic study of 104 unilateral congenital dislocations of the hip (CDH) that had an average age of 12 months (range 4-24), w ere treated with the same therapeutic protocol, and had an average six years follow-up (range 3-13). Radiographic changes were evident in th e proximal femoral epiphysis in 57 hips (55%). In 7 (7%) the changes c onsisted of central osteoporosis with a cystic aspect, without metaphy seal or physeal changes, and had a normal end result without sequelae. This group was classified as type I. Fifty hips (48%) that were type IT showed epiphyseal changes consisting of trabecular rarefaction with osteoporosis and irregular sclerosis, followed by a decrease of epiph yseal height and trabecular recovery. Forty-two hips (40%) were type I IA, with <75% decrease in epiphyseal height with respect to the health y side; five of these had a normal evolution, 35 had coxa magna and/or decrease of epiphyseal height, and only two cases had physeal lesion. In type IIB, hips, with >75% decrease of epiphyseal height, 8 cases ( 8%) had a final physeal lesion.