The 3D printing technology is penetrating the healthcare field at an astonishing rate. 3D printing in orthopedics is no exception. According to the MIT Technology Review, in 2016, surgeons around the world will implant tens of thousands of 3D printed replacements parts for hips, knees, ankles, parts of the spine, and even sections of the skull.
3D printing can form 3D supporting structures in a controllable manner and has been giving its first steps in fields such as tissue engineering and regenerative medicine along with the advances in cell printing and bioprinting and the innovation of printing materials. However, there is still a long way to go to realize organ printing.
In the clinical settings, 3D printing, as a novel additive manufacturing technique, is mainly applied in orthopedics and stomatology. A group of 3D printing-based patient-specific osteotomy instruments, orthopedic implants, and dental implants have been licensed by the FDA and CE.
Based on imaging techniques such as CT’s and MRI’s, the 3D images of the bones can be reconstructed; then, the prototypes of the bones can be obtained using the layered manufacturing technique (LMT) for teaching, presentation, and surgical design.
Based on the symmetry of the human anatomy, or by using the human anatomy data in database, it is also possible to reverse or mimic the 3D images of the bones at the missing parts, so as to assist the conventional mechanical processing to manufacture bone prostheses that can be implanted into human body. These two rapid prototyping manufacturing (RPM) techniques have been quite mature and commonly applied in surgery design.
Development of metallic implants and personalized prostheses is eventually the most important and most valuable direction, when applying the 3D printing in the field of orthopedics. This is determined by the materials, equipment, and manufacturing capabilities available for 3D printing. The commonly used metal materials, including several titanium grades (Grade CP1/2, Ti6Al4V), cobalt-chrome alloys (e.g., ASTM F75) and stainless steel (e.g. 316L), can be used for 3D printing and manufacturing.
One of the main advantages of 3D printing in orthopedic implants is the inherent geometric freedom of the technology. This not only allows the design of more natural anatomical shapes, it also brings the possibility of designing porous bone replacement scaffolds that can seamlessly be integrated in the implant design. This allows for natural bone ingrowth, ensuring a higher stability of the implant.
Using 3D printed replicas of bone fractures from patients is a perfect way of increasing successful first time results of orthopedic trauma surgeries. Some broken bones can be set with a cast, others require orthopedic surgery if they don’t heal the right way, which can cause chronic pain for the patient.
Surgical teams can use a 3D printed replica to simulate the surgery to determine which techniques or equipment should be used to make the surgery more successful. The 3D printed fracture replica lets physicians see exactly what is going on with a fracture before they even begin surgery or open up a fractured joint. In this case, the idea is to increase the success rate of the surgery on the first attempt so patients heal faster with no chronic pain. Overall, the innovation of using 3D printed replicas of bone fractures, organs or other body parts can help doctors, surgeons and researchers thoroughly test methods before the surgery even begins.
3D printing is the perfect technology to support the ongoing evolution of personalized digital medicine, creating a digital thread starting at the medical imaging process, over treatment planning, implant design, patient communication and ending with the digital manufacturing of a personalized implant and instrumentation.