3D printing promises to be a revolution in orthopaedic device manufacturing. In 3D printing, parts are built up layer-by-layer by adding to a workpiece using a variety of materials and energy sources. 3D printing is more technically called additive manufacturing (AM) to distinguish it from traditional machining, which “subtracts” material from a solid billet or from a rough part that was cast or forged.
Although AM has been used in nonmedical industries for some time, it is still a relatively new technology, particularly in medical applications, and requires a careful analysis of risk before new products are introduced into clinical use. Currently, most commercial activity in orthopaedics has been for standard-sized implants. However, some applications of 3D printing have also been for patient-specific implants.
Many of these implants are not truly custom, but cover a large range of size parameters cleared by the U.S. Food and Drug Administration (FDA) in a so-called “envelope submission” (a range of sizes and design parameters). A smaller set of applications have been used for 3D printing of truly custom implants, specific to one patient for complex reconstructions following trauma or surgical treatment of tumors. The regulatory distinctions among standard sizes, “patient-specific” implants, and truly “custom” implants are very stringent and clear, as detailed in FDA guidances. The use of 3D printing does not change these definitions or their regulatory requirements.
In orthopaedic surgery, both metallic and polymeric (plastic) parts are currently fabricated using AM. Many clinical applications have been proposed for 3D printing, using patient-specific data or allowing complex geometries. Commercial applications have thus far included the following:
- metallic implants, such as tibial baseplates, acetabular shells, and spinal cages with porous or complex geometries
- polymeric instruments such as patient-specific jigs
- custom polymeric and metallic implants for complex reconstructions, such as tumor surgery and craniomaxillofacial surgery
The explosion of such leading-edge applications has created a need for careful regulation to ensure such devices are safe and effective.
By S. Raymond Golish, MD, PhD, MBA; Steven M. Kurtz, PhD; and Barbara D. Boyan, PhD | AAOS
Image Credit: 3dprint.com