Cause and prevention of osteochondritis in congenital dislocation of the hip.

All treatment modalities of congenital displacement of the hip (CDH) bear the risk of ischemic necrosis at the proximal femoral epiphysis. The causes of ischemic necrosis were investigated in a review of the literature and personal experience with CDH patients during the past 30 years. Compression of articular cartilage, caused by an increase in intraarticular pressure, has been implicated as the mechanism of osteochondritis. Muscle spasm, pressure on posterior circumflex vessels, and compromised pericephalic microcirculation in the newborn have been demonstrated to increase intraarticular pressure. The most dangerous causative factors include forced reduction under general anesthesia, spica cast immobilization of the hips in the Lorenz or Lange position, insufficient continuous prereduction traction, and splints or braces that are either too rigid or that force the hip into an extreme position. An intertrochanteric varus osteotomy can also lead to ischemic necrosis when performed at the time of reduction. Preventive measures include sufficient continuous traction, casting in a moderate position, and bracing that allows active movement. None of these measures constitute a guarantee against necrosis, but they will lessen the incidence and severity of involvement.