Video: Smith & Nephew on 3D Printing Patient-Specific Surgical Instruments
Medical device maker Smith & Nephew is using MRI measurements of knee-replacement patients in conjunction with 3D printing to make a “cutting block” that is tailored to the precise dimensions of the patient. The custom instrument aids the precision and efficiency of a surgical procedure that is becoming increasingly common. Smith & Nephew’s Mark Morrison discussed this custom surgical tooling in a conversation we filmed at the Additive Manufacturing Conference.
Peter Zelinski, Additive Manufacturing
I'm Pete Zelinski with Additive Manufacturing magazine. And I am here with Dr. Mark Morrison, who is manager of research and tribology with Smith & Nephew. Mark, Smith & Nephew is using 3D printing to make instruments that reduce the time and trauma of surgical procedures many of us are very familiar with. What is the surgical procedure and describe the instrument.
Mark Morrison, Smith & Nephew
So, we have these patient-specific instruments for total knee arthroplasty or knee replacement, and so we take imaging from the patient before surgery. We construct a model of their bone, then we create a patient-specific additive-manufactured cutting block or instrument, essentially, that we print and ship to the hospital for the surgery and the surgeon uses that. It fits like a glove, basically, on the patient's bone, and helps a surgeon precisely place cuts. And, better, be more efficient in the OR with that surgery and hopefully more precise in the implantation of that device.
Custom fit to the patient. Can you describe that process? How is the patient measured and how does that result in a customized tool?
Right, so we use…. At Smith & Nephew, we use MRI imaging of that patient, and so MRI takes high-resolution images of anatomy in slices, so we segment those slices to segment bone and everything else. We take those slices of bone and create a 3D model of that patient's bone and then we can do many iterations of planning the surgery. We can tweak the surgical plan and see what works best for this patient. We propose that plan to the surgeon. And ultimately, he signs off on what he's happy with and then we use that model and that surgical plan to design this patient-specific instrument.
So, you use the word “instrument.” Our audience—manufacturers—would think of it as tooling. You're creating tooling that is geometrically customized to the patient. And I wonder if you could talk to me about that from the patient's perspective. Why is it so valuable to have patient-matched instrumentation?
The placement of that implant in the body relative to the patient's anatomy is very important to the performance of that joint. With the patient-specific instrument we can better control that. We can help the surgeon plan, number one, and two, better implant it in the right place and hopefully provide better longevity of that implant for that patient.
What is the material the instrument is made out of and what machine do you produce it on?
We're using an EOS 3D printer or additive manufacturing system and we're printing those devices out of nylon.
All right, so we've been talking about tooling for surgery, customized instruments. Smith & Nephew uses additive also to make implants. Can you talk about that?
Yeah, so at the beginning of 2016 we launched our first additive-manufactured implant. It’s an acetabular shell for a hip replacement and additive, what that's allowed us to do in that space is to create our own proprietary porous structure. Additive provides the opportunity to custom-design what that surface feels like and looks like and how it grabs onto the bone and holds that device in place.
How would you make a weight-bearing manifold without machining?
Far from being opposite or competitive processes, additive manufacturing and CNC machining actually go together. They belong in the same machine.
DMG Mori produced the part seen in this video to demonstrate the capabilities of its new hybrid machine, which is capable of both CNC machining and additive manufacturing through laser metal deposition.