3-D Manufacturing in Orthopedic Surgery
The future of orthopedic surgery, and advancements for patients managing the effects of arthritis, fractures, and other musculoskeletal conditions, is a subject of constant interest. From stem cells to joint replacements, surgeons and patients alike are interested in what might be the next advancement around the corner.
One of the areas of recent interest has been development of tools and implants that are custom made and patient-specific. The hope is that by allowing for the design of more custom implants, orthopedic interventions will be better accommodated and less noticeable for people who need to undergo a surgical procedure.
Manufacturing of Implants
The healthcare industry is heavily reliant on manufacturing to supply the various products used throughout the medical profession. Orthopedic surgeons rely heavily on manufactured products, and developments in manufacturing have revolutionized orthopedics in a variety of ways. From nonsurgical treatment of sports injuries treated with carbon fiber custom braces to surgical reconstruction of deformed limbs, orthopedic surgeons utilize many different materials and products to help their patients.
Anytime there is an advancement in manufacturing, orthopedic surgeons are likely to be interested in how this might affect the work that they do. One of the recent changes in manufacturing is the advancement of 3-D printing technology. Three-dimensional printing has changed the way many industries are manufacturing products. The healthcare industry is no different, and many applications of 3-D technology are being produced to address various healthcare needs. In orthopedic surgery, a medical specialty that relies heavily on implantable devices, 3-D printing technology has been an area of great interest.
The major difference noted with 3-dimensional manufacturing is that this is a so-called “additive manufacturing” process. this means that implants are created by adding material layer by layer to create a 3-dimensional product. This is distinguished from a “subtractive” process where a block of material is sculpted into a desired shape. Additive manufacturing has been around for a number of years and many industries but is relatively new to the healthcare industry.
Traditionally, orthopedic implants are designed in multiple different sizes. For example, if you were getting a hip replacement, much like going to a shoe store and trying on different sizes of standard shoes, your orthopedic surgeon would have a variety of hip implant options designed to fit most people. While these implants often work well, there are limitations in the numbers of sizes, and some people have anatomy that does not conform well to a specific standard size.
In orthopedic surgery, 3-dimensional printing has been used for a number of different applications. For example, joint replacement implants have been custom fabricated. Some of these implants have been used in common surgical procedures such as hip replacement and knee replacement surgery. In addition, spinal implants have also been designed through 3-dimensional additive manufacturing. Another application has been the design of patient-specific instrumentation. In this situation, the actual implants used are standard sizes, but the instruments that your surgeon uses to prepare for the implant are custom designed. Lastly, additive manufacturing has been used for the design of complex implants used for severe deformities, tumor surgery, and situations when there are no standard implants available for complex reconstructive surgery.
Many patients are interested in custom implants. They want to ensure that the implants used at the time of their joint replacement are sized perfectly for their body. At present, it is very uncommon for a surgeon to actually implant a custom-made joint replacement. Usually, when people are talking about custom implants, they are actually having a standard implant inserted, and a custom cut is designed for their specific anatomy. Custom joint replacements, where the implants are actually designed specifically for an individual patient, are not a standard surgical procedure at this time.
The potential advantage of a true custom implant, where the implanted prosthesis is specifically designed for an individual patient, is the ability to replicate the normal mechanics of a joint. There are circumstances where a standard size implant may be a little too long, a little too short, a little too wide, or a little too narrow. In most people, your surgeon can compensate for the subtle variations, but there are some situations where people have unusual anatomy they can be difficult to adapt to standard implants. Custom implant design could allow your surgeon a better ability to control for these variables.
Adhering to Bone
The other aspect of additive manufacturing that is of interest to your surgeon is the ability to design implants that will adhere well to the surrounding bone. There are different ways to secure an implant to the bone. The use of screws and wires is typically used for fracture treatment, where the implant only needs to last until the fracture is healed. The use of bone cement is common, but the use of it has declined. While this is an effective method to secure an implant, there are concerns about implants coming loose over time. One of the best ways to secure an implant to the bone, is to use implants with a porous coating the bone can grow into over time.
Porous coated implants are often used in joint replacement surgery, but not all implants can be easily designed with a porous coating. 3-dimensional printing has made the process of applying a porous coating to a broad variety of geometric surfaces more possible.
The future of orthopedics will undoubtedly look very different from the way things are being done today. One of the more exciting areas is the development of new technologies to manufacture orthopedic implants. 3-dimensional printing is a technology that is being used to design a custom orthopedic implants that are currently used for complex reconstructive surgeries. Over time, the use of 3-dimensional printing may become more common and used more broadly for standard orthopedic surgical procedures.
- Golish SR, Kurtz SM, Boyan BD. “Can 3D Printing Revolutionize Orthopaedic Devices?” AAOSNow. January 2018, Page 1.
- Haglin JM, Eltorai AE, Gil JA, Marcaccio SE, Botero-Hincapie J, Daniels AH. “Patient-Specific Orthopaedic Implants” Orthop Surg. 2016 Nov;8(4):417-424.