Summer 2005

Hip Replacement Alternative for Dysplasia

Adult and mature teenage patients suffering from developmental dysplasia of the hip now have a joint-conserving procedure as an alternative to joint replacement surgery.

Periacetabular osteotomy involves carving the acetabulum out of the surrounding pelvis and rotating it into better alignment with the femoral head, explains Mohammad Diab, M.D., one of the few West Coast orthopaedic surgeons who performs the procedure.

"If the hip joint has dysplasia without significant degenerative changes, the best treatment is periacetabular osteotomy, as this preserves the patient's own hip, which is always better than replacement," says Diab, chief of Pediatric Orthopaedics at UCSF Benioff Children's Hospital.

The incidence of all developmental dysplasia is about one in 1,000, but most cases are detected in childhood due to neonatal screening. Most children — about 90 percent — will be successfully treated with bracing, while another 10 percent require surgical treatment. Some patients, however, aren't diagnosed until they are physically mature and begin to experience hip pain, often in the groin, in their teens and 20s.

Periacetabular osteotomy, devised in the late 1980s by Dr. Reinhold Ganz of Bern, Switzerland, is just starting to be performed in the United States, although it has been done on thousands of European patients. Diab says the procedure is a demanding one for the surgeon. It requires four principal cuts -- including two "blind" cuts in which the surgeon can't actually see directly where he or she is cutting -- to create a wider opening for the hip socket.

"The surgeon has to understand the complex three-dimensional geometry of the pelvis to do this," says Diab, who has performed dozens of these procedures. "But the results have been gratifying, with excellent patient outcomes in the mature teenager and young and active adult."

Prior to the Ganz procedure, the available surgical options included so-called "salvage" pelvic osteotomies, in which the femoral head is covered with raw bone obtained from the adjacent pelvis, or ablative procedures. The latter include total hip arthroplasty, which is effective in relieving pain, but requires significant activity restriction to avoid loosening the artificial components. Young arthroplasty patients also require at least one revision or repeat operation because the components loosen with time, no matter how careful the patient is.

On the other hand, the Ganz procedure is durable and should last for the patient's lifetime without restricting activity or requiring a subsequent operation. Diab says UCSF is completing a study that indicates the Ganz procedure is more cost-effective and beneficial to the skeletally mature teenager and young adult without advanced osteoarthritis than total hip arthroplasty.

After the operation, the recovery period is usually six to eight weeks of protected weight-bearing with crutches while the patient begins strengthening exercises, particularly of the hip abductor muscles. After the eighth week, the patient's activity is advanced according to how well he or she is recovering clinically and radiographically, based on muscle strength and radiographic evidence of bone union. While the patient is mobilized on the first postoperative day, it takes six months for the patient to return to full activity.

For more information or to refer a patient, please call Dr. Mohammad Diab in UCSF Pediatric Orthopaedics at (415) 353-9384.

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