3D Printed Models are Changing Joint Replacement Surgery

Osteoarthritis is one of the most common forms of arthritis (inflammation in the joints), affecting around 31 million Americans. It arises when cartilage (the tissue that covers the ends of bones) in our joints begins to break down, a process that is triggered by overuse and/or aging, and which gradually worsens over time. Cartilage provides padding that allows the bones in joints to glide smoothly against each other when we move. Without this padding, movement brings pain, stiffness, and swelling. Arthritis can even damage the surfaces of the bones.For some people with osteoarthritis, medication, injections, or changes in lifestyle are enough to manage the condition. But when these treatments aren’t enough—and when the pain begins to prevent you from living your normal life (working, exercising, walking, sleeping)—it may be time for another treatment approach: total joint replacement surgery. “Total joint replacement is when we replace the surfaces where the cartilage has been broken down or worn out with metal or plastic or ceramic surfaces,” says Daniel Wiznia, MD, an orthopedic surgeon at Yale. Dr. Wiznia, who also has a background in mechanical engineering, uses 3D printing to customize his surgery to each patient. Using MRI and CT scan images to obtain precise measurements, he produces a solid, three-dimensional model of the patient’s anatomy. This model is used to create custom tools and implants individually designed for each patient. “Everyone’s anatomy is unique, which means the shape of your bone is going to be different from the shape of someone else’s,” Dr. Wiznia says. “So, you would want implants made specifically for you and a surgery that is customized specifically to you.” To do this, Dr. Wiznia follows a multi-step process, starting with software that helps him create a 3D representation (virtual model) of the patient’s joint from a high-resolution CT scan or MRI. He then uses that computer model to determine the best way to fit the implant prior to surgery. “Where, traditionally, surgeons would use different alignment orientation guides during the surgery, we now know that they’re not as precise or accurate during the surgery than if you use this technology,” Dr. Wiznia explains. Custom implants improve patient outcomes long-term. Data show that after surgery patients are able to resume their normal activities sooner, require fewer blood transfusions, and are less likely to be readmitted to the hospital.