Making the Cut: Drexel Researchers Develop New Simulated Surgical Modeling for Orthopedics

Resin Model of a pelvis Advanced 3-D printing technology will allow physicians to perform simulated surgical procedures using an exact replica of a patient's pathology.

PHILADELPHIA, April 11, 2013 — Researchers at Drexel University are taking a closer look at the way orthopedists prepare for surgery. Sorin Siegler, a professor in the Department of Mechanical Engineering and Mechanics is working closely with physicians at the Children’s Hospital of Philadelphia to develop new 3-D modeling techniques to assist in planning for orthopedic surgeries.

The partnership with Dr. David Horn, an attending surgeon of orthopedics at the Children’s Hospital of Philadelphia, focuses on designing a surgical planning method using 3-D modeling that will allow physicians to visualize a patient’s orthopedic pathology instead of extrapolating from a model of a healthy individual.

A child born with Bladder Exstrophy, a rare congenital disorder in which a portion of the urinary bladder is located outside of the body, will serve as a test case for this new method.  Children with Bladder Exstrophy commonly suffer from hip dysplasia. A disorder where the pelvic bones are rotated too far outward, resulting in physical deformities and difficulty walking. Treatment for this type of dysplasia usually involves a Pelvic Osteotomy, a surgical procedure where controlled cuts are made to the pelvic bone with pins and clamps inserted to reshape the pelvis.

Surgical planning for a Pelvic Osteotomy is often challenging especially in pediatric patients due to the small size of the bones, the precise location of the cuts and crucial placement the two millimeter pins used to anchor the bones.

“It’s like an almost impossible puzzle, if you can understand the puzzle pieces ahead of time the task becomes much easier,” Siegler said.

Siegler used Analyze Direct, a software program developed at the Mayo Clinic, to create a 3-D rendering of the child’s pelvis. Siegler then transferred the rendering to 3-D printer to create a functional, scale model out of plastic resin. Horn will then use the renderings and the plastic model to simulate the precise cuts and pin placements required to reshape the pelvis prior to entering the operating room

“It’s a very small pelvis with very small hardware. It really helps preoperative planning that we can figure out where to make the cuts and where to place the pins to be most effective,” Horn said. “I think it’s going to very useful when we perform the surgery,” he added.

Siegler sees potential for this type planning for a variety of orthopedic injuries from complicated fractures to joint replacements. He hopes his research will lead to a partnership with hospitals to establish an orthopedic surgical planning facility at Drexel to serve future surgeons in designing and planning complicated orthopedic procedures.

“The ability to see the impact of engineering on a clinical practice is very rewarding. I believe there is a great need for a center that will allow surgeons to experiment with a wider range of surgical approaches to treat severe orthopedic injuries,” Siegler said.