Congenital dislocation of the hip. The relationship of premanipulation traction and age to avascular necrosis of the femoral head.

A retrospective study involving 276 patients with 319 congenitally dislocated hips was undertaken to assess whether premanipulation fraction prevents avascular necrosis. Roentgenographic criteria were utilized and only cases of frank dislocation unassociated with other disorders were included. It was found that in a child less than one year old, premanipulation traction of twenty-one days or more substantially reduces the incidence of avascular necrosis. For the child more than a year old, however, the prognosis is not as good, even if premanipulation traction is prescribed for twenty-one days or more. We found a 14 per cent incidence of avascular necrosis in children less than three months old and suggest that the cartilaginous femoral head prior to the appearance of the ossific nucleus is particularly vulnerable to vascular injury.