Additive manufacturing (AM) technologies are allowing surgeons to simulate procedures using life-size anatomical models, created directly from a patient’s computed tomography (CT) scan or magnetic resonance imaging (MRI) picture. Recently, engineers at Dinsmore Inc. – an Irvine, California-based manufacturer specializing in rapid manufacturing, 3D printing, and product design and development – completed a patient-specific project with the Children’s Hospital of Orange County (CHOC), Orange, California.

The patient, 18-year-old Moises Campos, had a tibial tubercle fracture from an earlier injury that arrested growth below his kneecap and deformed the tibia. Affecting his ability to walk and run, the deformity also put him in danger of early onset arthritis, and the only remedy was to cut the bone and slowly move it back to the correct position.

3D model

Pediatric orthopedic surgeon Dr. Afshin Aminian, medical director of CHOC Children’s Orthopedic Institute, contacted the Dinsmore team to work with him and his team on a 3D model of the tibia prior to surgery. The complex nature of Campos’ bone deformity could make intra-operative assessment difficult. Creating a customized 3D model of the deformed bone would allow the surgical team to see, study, and plan for deviations from typical anatomy, eliminating much of the guesswork from the operation.

Using CT scan data provided by the hospital, Dinsmore’s in-house designers converted the data of bone anatomy into a surface model from which they 3D printed a model of the bone.

“We were excited to take on this project and hopefully have a positive impact on Moises’ surgery,” says Jay Dinsmore, president and founder of Dinsmore. “We printed several models with the data from a series of CT scans over a few weeks. The front-end work of ensuring data integrity was the most time-intensive step of the process, but also the most important.”

The Dinsmore team used stereolithography (SLA) to produce the model – a process often chosen for its precision and speed. To achieve the most realistic aesthetic results, Dinsmore’s team only partially cured the resin during post-processing to produce a density and surface finish closely resembling bone.

Points of contact between the object and its supports are wet-sanded to achieve the desired finish.

Set for surgery

Advanced surgical planning provides smoother and more effective execution during operations, leading to a better outcome for the patient. So, with the printed model in hand, Aminian’s team planned their cuts and fitted the bone with the right external fixation construct.

Surgical team member Dr. Justin Roth notes that, “for complex surgeries like this one, the 3D physical model was a great conceptual practice tool for pre-surgical planning. It gave us a tactical visualization of the deformity, so we could get a better sense of what was needed to correct it. You can measure the deformity in CT scans, but there’s nothing like being able to hold the physical model.”

Roth also notes the value of having the model in hand to educate the patient and family about the procedure. “It’s nice to be able to take the model and show patients what’s going to happen during surgery.”

Collaboration between the surgeons at CHOC and the team at Dinsmore produced a successful surgery that restored Campos’ normal gait and function in four months. Six months post-surgery, Campos returned to his normal activities without any restrictions.

Dinsmore Inc.
www.dinsmoreinc.com

Designers at Dinsmore used CT scan data, converted into a surface model to 3D print a model of the deformed bone.