Interview with Mark Morrison, Manager, Materials Research and Tribology, at Smith & Nephew, USA.
Question: How is Additive Manufacturing actually used in orthopaedics and what are the prospects for the future?
The first widespread, commercial use of AM in the orthopaedic industry was the fabrication of patient-specific instruments for total knee arthroplasty. Since then, applications have expanded into the fabrication of implantable devices. In general, most of these products have been devices like acetabular shells with porous bone-interfacing surfaces that allow bone to grow into the pores to hold the implant in place. AM is particularly advantageous in this particular application because it allows for the creation of advanced, custom porous structures that can be fabricated in fully porous, bulk forms if desired. Finally, AM is being used to fabricate patient-specific implants for complex cases and/or deformities.
Q: Is Additive Manufacturing really set to revolutionize orthopaedic product manufacture?
“Revolutionize” is a strong word. AM is not a replacement for conventional manufacturing processes and probably won’t be. It is simply another tool in the toolbox. For the near future, AM is going to be used in applications where there is a clear value proposition over conventional, subtractive methods. As additive manufacturing becomes faster and cheaper, the applications with good value propositions will likely expand.
Q: How involved in Additive Manufacturing is your company?
Smith & Nephew has been involved in the research and development of additive manufacturing for medical devices for more than a decade. Our initial work in this area was in the development of patient-specific instruments for total knee arthroplasty procedures. Based on imaging of a patient’s anatomy, a virtual surgical plan is produced to define the sizing and positioning of the implants. Once that surgical plan is approved by the surgeon, custom cutting blocks are produced via powder bed fusion of nylon, cleaned, packaged, sterilized and sent to the hospital within three weeks. Introduced commercially in 2009, Smith & Nephew has since performed over 100,000 cases with these AM instruments.
More recently, Smith & Nephew is developing a revision system for total hip arthroplasty, which is fabricated through powder bed fusion of Ti-6Al-4V. Additive manufacturing allowed us to design a custom, randomized porous structure for bone ingrowth and incorporate other features that are designed to improve the performance of these devices in challenging surgical cases. The first phase of this system was a fully porous acetabular shell, which represented our first AM implant and was first implanted in January, 2016.
Q: Is the technology and are the machines mature enough today to meet market needs?
AM technology is certainly mature enough to meet niche market needs in orthopaedics (e.g., low volume, high value devices). The increasing number of AM devices on the market is proof of this. However, in my opinion, further improvements in print times and lower powder and machine costs are needed to expand to higher volume, lower value devices.
Q: Is Additive Manufacturing only adapted for internal manufacturing by orthopaedic companies, or can subcontractors also exploit it for their customers?
Additive manufacturing has been adopted by both OEMs as well as vendors/subcontractors. Some orthopaedic companies have chosen to produce AM instruments and/or devices internally, while others have utilized vendors. In my opinion, there is plenty of room for both OEMs and subcontractors to innovate with AM in this market space.