June 2015

Out on a limb: 3DP’s material needs

1Limb-JordanaBy Jordana Bieze Foster, Editor

3D printing is no longer some futuristic concept that might someday affect lower extremity healthcare. It’s here, and it’s already changing the landscape more quickly than many had expected. But, as anyone who follows journalists on Twitter can attest, the battle to be at the forefront of something new often leads to critical details being overlooked.

At the recent Ortho Technology Forum (see “Conference Coverage: Ortho Technology Forum 2015,” page 29) and at the joint meeting of the Pedorthic Association of Canada and the Prescription Foot Orthotic Laboratory Association that followed, much of the discussion about 3D printing involved concerns that the technology will encourage the emergence of entrepreneurial orthotic device companies with business strategies that emphasize cost over quality. And, certainly, that’s a legitimate concern.

But to me, the bigger issue with 3D printing is that even companies or clinicians who want to create quality orthotic products using the technology may not be able to do it. That’s because the types of materials that are amenable to 3D printing, and the way those materials behave once they’ve gone through the additive manufacturing process, could end up being completely different from the subtractive manufacturing world.

For starters, many of the materials that have traditionally been used for orthotic devices simply can’t be used in a 3D printer. Research and development departments have been working to identify alternative materials that are compatible, but it will take time to determine just how well those additive materials compare to their subtractive counterparts in terms of clinically relevant characteristics, such as how the material responds to dynamic weight bearing or shear forces.

Even in cases in which traditional orthotic materials actually do lend themselves to 3D printing, another hurdle to overcome is that the manufacturing process itself can change the properties of the material.

We can’t assume that anything we know about the material properties of orthotic devices will be true for 3D-printed devices.

One challenging aspect of additive manufacturing is that products are typically composed of numerous micron-scale beads piled on top of one another, according to a recent statement from the Defense Advanced Research Projects Agency announcing its Open Manufacturing program. “Even when well-known and trusted alloys are used, the additive process produces a material with a much different ‘microstructure,’ endowing the manufac­tured part with different properties and behaviors than would be expected if the same part were made by conventional manufac­turing,” the statement read.

So, essentially, we can’t assume that anything we know about the material properties of traditional orthotic devices will be true for 3D-printed orthotic devices. Clinically, that seems like a big problem.

I do believe that 3D printing has the potential to take orthotic therapy to the next level. But it will take extensive research to develop any type of clinical confidence in 3D-printed orthotic materials—research that, as far as I can tell, is only in its earliest stages.

In the meantime, jumping on the 3D printing bandwagon may be good for business. But without evidence of clinical effectiveness, it’s impossible to know whether it will be good for patients. That’s not a risk I’d be willing to take just yet.

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