Modeling a More Efficient Hip Surgery

By Thomas Crocker
Monday, January 1, 2018

Preparing for surgery to correct a comparatively common hip condition among youths can be challenging, but researchers at the University of California, San Diego, may have found a solution: 3-D-printed models.

Slipped capital femoral epiphysis (SCFE) affects more teenagers than any other hip disorder, according to the American Academy of Orthopaedic Surgeons. It occurs when a fracture of the proximal femoral growth plate in the hip, at the top of the femur, causes the neck of the bone to slip out of position. Obesity seems to be a key risk factor.

The condition can cause hip pain, a limp and abnormal rotation of the leg, according to the National Institutes of Health. Over time, it may lead to avascular necrosis and osteoarthritis of the hip.

Using X-rays and CT scans to plan triplane proximal femoral osteotomy (TPFO) — the traditional surgical treatment for mild to severe SCFE — has significant limitations.

“If you break up that axis of the [femoral] neck into X, Y and Z planes, every child’s slip is different in those planes,” says Vidyadhar Upasani, MD, Co-director of the International Center for Pediatric and Adolescent Hip Disorders at Rady Children’s Hospital–San Diego and Assistant Clinical Professor of Orthopedic Surgery at UC San Diego. “Because of the 3-D nature of the slip, it’s difficult to precisely understand the extent of deformity and the best plan to correct it.”

Plotting a Surgical Path

Dr. Upasani and his co-investigators wanted to determine if using 3-D-printed models of patients’ proximal femurs could aid in planning TPFO. In a retrospective study, they compared the results of 10 SCFE surgeries Dr. Upasani performed — five with preoperative 3-D modeling and five without — to five surgeries two of his colleagues completed without 3-D-printed planning aids. Use of the 3-D models reduced surgical time by up to 45 minutes and intraoperative time needed for fluoroscopic guidance by up to 50 percent, on average.

“With the 3-D-printed model, I knew the type of cut I needed to make in the bone to end up with the final outcome, so I didn’t need to use those X-rays as markers along the way,” Dr. Upasani says. “We’re getting to the same appropriately corrected bone as before, just ... in a more efficient way.”

The modeling may allow patients to avoid future complications of SCFE, says Amy McIntosh, MD, Associate Professor of Orthopedic Surgery at Texas Scottish Rite Hospital for Children, who was not involved in the study.

“The model helps surgeons see the deformity and ... correct it to the most normal anatomy possible,” Dr. McIntosh says. “The hope, then, is that it will translate to the patient’s not developing arthritis and needing total hip replacement at 40.”