Issue link: http://viewer.e-digitaledition.com/i/945876
PREPARING FOR SURGERY TO CORRECT A COMPAR ATIVELY COMMON HIP CONDITION AMONG YOUTHS CAN BE CHALLENGING, BUT RESE ARCHERS AT THE UNIVERSIT Y OF CALIFORNIA, SAN DIEGO, MAY HAVE FOUND A SOLUTION: 3DPRINTED MODELS. More Efficient Hip Surgery BY THOMAS CROCKER SLIPPED CAPITAL FEMOR AL EPIPHYSIS (SCFE) aects 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 dierent 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 di˜cult 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 e˜cient way." The modeling may a llow 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." ■ Modeling a Surgical Guideposts A F TER DEMONSTR ATING THE benefits of using 3-D-printed models to plan surgery for slipped capital femoral epiphysis, University of California, San Diego, researchers are investigating a way to enhance the operation itself. "The next step is to make a cutting guide to attach to the patient's bone that can simulate [where to make] the cut," 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. "That would make [the surgery] even more precise." 1 4