Incidence of avascular necrosis of the femoral head in congenital hip dislocation related to the degree of abduction during preliminary traction.

Two-hundred and twenty-two congenitally dislocated hips of 173 patients had been abducted in one of two fashions, prior to closed reduction under general anaesthesia. In both forms of treatment, the hips were in 90 degrees of flexion while they were abducted. Group 1 included those who were abducted up to 90 degrees and Group 2 those who were abducted to not more than 60 degrees. The incidence of total avascular necrosis was 90% when the limbs were abducted to no more than 60 degrees and 17% in those abducted up to 90 degrees. The incidence of partial avascular necrosis was not affected by the degree of abduction of the hips. The incidence of avascular necrosis in Group 2 patients is comparable to that in recent reports of patients who received their traction with the hips in extension; this suggests that the flexed position is not harmful, and it is certainly effective and convenient.