Reduction of CDH by the Pavlik harness. Spontaneous reduction observed by ultrasound.

Ultrasound was used to observe the entire course of spontaneous reduction of CDH in the Pavlik harness in nine infants. In six infants with Suzuki type-A dislocations, the femoral head settled slowly into the bottom of the acetabulum by gliding on its posterior wall. In type-B dislocations, passive abduction of the legs during sleep caused it to approach the entrance to the socket and then suddenly to slip in. Reduction with the Pavlik harness is due to passive mechanical factors, and occurs only during muscle relaxation in deep sleep: no active movement is involved.