We report the complications of prophylactic pinning of slipped upper femoral epiphysis with Crawford Adams pins in 95 cases. Complications of pin placement were seen in 13.7%. Although seven hips had penetration of the joint, there were no cases of chondrolysis or avascular necrosis. Excavation of the lateral femoral cortex was required at pin removal in 12.5% of cases. Analysis of the growth around pins allowed recommendations to be made regarding pin protrusion. The use of improved fixation devices may reduce the need for multiple pins.

The results of open reduction of the severely slipped upper femoral epiphysis are reported for 115 hips with an average follow-up of 12 years 11 months (range 2 to 33 years). In 70 hips with a chronic slip and an open growth plate the incidence of complications was low: two developed avascular necrosis, five chondrolysis, and one had both. There were more complications in the 38 hips with an acute-on-chronic slip: six developed avascular necrosis, one chondrolysis, and three had both. Of the seven hips operated upon with a partially fused plate, only one did well. All these complications were obvious within the first year but there were also three hips in the series in which osteoarthritis developed between 10 and 20 years after operation.

The stages in adolescent slipping of the upper femoral epiphysis are classified in relation to treatment. The operation of open replacement of the displaced femoral head is described, and the results of a personal series of seventy-three such operations are presented. Open replacement is excellent treatment for severe chronic slipping so long as the growth plate is still open. The greater incidence of avascular necrosis in acute-on-chronic cases is probably due to damage to the blood supply of the head at the time of the acute slip or kinking of the vessels before replacement. Prolonged traction before operation may increase the risk of chondrolysis. Late onset of osteoarthritis when neither avascular necrosis nor chondrolysis has occurred may be due to misfitting of the articular cartilage because of inaccurate reduction.