Three-dimensional (3D) printing is defined as a process that builds 3D objects from a computer-aided model by successive addition of material layer by layer, in contrast to conventional forging, casting, or machining processes, in which material is poured into a mold and shaped by forceful impaction.
The 1980s saw the advent of 3D printers, which produced simple objects at high costs. In the four decades since its introduction, the complexity achieved by 3D printers has improved considerably, while the prices have dropped. These production methods are now used in a wide range of fields, including manufacturing, architecture, food, and medicine.
3D printing can be used to manufacture custom machine parts, auto bodies, firearms, airplane components, engines, and circuit boards. The heterogeneity of musculoskeletal anatomy and high cost of implant storage have led to the adoption of 3D printing within orthopaedic surgery.
The process of creating a 3D model in orthopaedic surgery typically begins with 3D imaging of bone, most commonly with CT. The image is then converted into a format recognized by the 3D printer software. The 3D printer then creates the 3D-printed model or implant layer by layer. Each 3D model can be made with a variety of materials, specifically chosen based on the intended application of the model; the most commonly used materials include ceramics and synthetic and natural polymers. For example, titanium is best used for implantation, and metals and bioceramics are best used for implants and bone restoration.
3D printing is now routinely used in orthopaedic surgery to print patient-specific anatomic models, implants, surgical instrumentation, external fixator splints, and surgical cutting guides. For example, surgeons use a patient’s two-dimensional images to create a personalized, 3D surgical plan. Surgeons can use these models to understand the often-complex 3D anatomy, especially in rare deformities and tumors, prior to surgery. The utility of preoperative 3D-printed templating was validated by a study comparing the surgical plans of residents who were given a 3D-rendered image versus a 3D-printed model. Residents who received the 3D-printed model had higher surgical plan scores compared to those who received the 3D-rendered image, demonstrating the potential value of 3D models for the education of patients, residents, and medical students.
By N. Mehraban, MD; D. Bohl, MD, MPH; S. Jacobson, MD; K. Hamid, MD, MPH, FAAOS | AAOS Now
Image Credit: Additive Orthopaedics