When 3-D printers were first developed about 30 years ago, the technology had limited capabilities and were large and cost prohibitive. Now that the technology has shrunk both in size and cost, 3-D printing is more usable across a broad range of fields, including medicine. More orthopedic surgeons are harnessing the power of 3-D printing to improve their knowledge of anatomy and pathology, and to achieve more consistent surgical results.
“Three-dimensional printing allows you to visualize and in some cases, practice surgical procedures for patients who have complex deformities or injuries in a way that we could not do before,” Jason L. Koh, MD, director of NorthShore Orthopaedic Institute, said. “It is transformative in the sense that our imaging was always in 2-D, and now we can have 3-D models that we can hold and manipulate. This allows us to have something that, in many cases, is probably closer to the reality of what we have to do in treating the patient.”
Also known as additive manufacturing, 3-D printing has been around since the 1980s. The process involves creating a 3-D, solid object from a digital model, which is often created using a computer-aided design program. In orthopedics, that requires data from MRI or CT scans. Once the digital model is complete, it is sliced into thin cross-sections that are layered one after another until the object is completed.
Although many materials can be used in a 3-D printer, some common materials used in orthopedics are sintered powdered metal, stainless steel, nitinol, titanium and ceramic, according to information from the American Society of Mechanical Engineers.
According to Craig J. Della Valle, MD, professor of orthopedic surgery and chief of the Division of Adult Reconstruction at Rush University Medical Center and Orthopedics Today Editorial Board member, 3-D printing technology can be most applicable during revision surgery, specifically revision total hip arthroplasty, due to the ability to more easily plan for complex total joint cases.
“If you have someone who has a large acetabular defect, sometimes it can be challenging from plain X-rays or a CT scan to understand where there is bone loss and where there is not,” Della Valle said. “The most obvious application, in my mind, is to get a CT scan and then build a model of the pelvis that you can understand and preoperatively plan with the model in your hand to get a preview of what you are going to see in the OR. If the manufacturer can print you an implant that fits the defect well, then that would make it a lot easier than what we are doing today.”
According to Michael J. Yaszemski, MD, of the Orthopedic Surgery Department and the Biomedical Engineering Department at the Mayo Clinic and John Posy Krehbiel endowed professor of orthopedic surgery and biomedical engineering, using 3-D printed materials to practice total joint replacement surgery ahead of the surgery “makes for a safer operation, more realistic expectations by the patient when they can see what the change is going to be and what the surgery makes, and understand the likely outcomes, the potential difficulties [and] the potential problems that can occur.”
“[Three-dimensional printing] allows us to go into a complex procedure with a unique anatomy being confident and comfortable,” Koh said. “It is easier to figure out exactly where we are making cuts or placing hardware, rather than trying to do that for the first time when looking at it.”
In addition, Koh said 3-D printing accelerates component placement.
“There are some data showing [3-D printing] speeds the ability to place the component accurately,” Koh said. “It may be useful for fracture cases, where you know you have multiple fragments that you are trying to figure out. Where we have found it particularly useful is in preparing for complex osteotomies treating fracture malunions or trochlear dysplasia.”
By Colleen Owens & Casey Tingle | (Healio) Orthopedics Today
Image Credit: Materialise