July 2014

Documenting CAD-CAM’s clinical relevance

By Jordana Bieze Foster

Foot orthoses made with advanced design and manufacturing technologies aren’t just technically impressive—they’re also clinically relevant, according to the results of two studies presented in June by keynote speakers at the Orthotics Technology Forum (OTF) in Chicago.

In one study, an advanced design technique that incorporates plantar pressure data into the traditional shape-based method was used to create foot orthoses that significantly reduced forefoot plantar pressures and ulcer recurrence in high-risk diabetic patients more effectively than conventional foot orthoses. The findings of the randomized controlled trial were published in the July issue of Diabetes Care.1

“Most of us worship at the altar of foot shape at the moment,” said study coauthor Peter Cavanagh, DSc, PhD, who presented the findings at the OTF. “When you are choosing where to put an offloading intervention [eg, a metatarsal pad], the chances of getting it in the right place are very small. So we end up with trial and error, where the trial is your best guess and the error is the development of a foot wound.”

Cavanagh is Endowed Chair in Women’s Sports Medicine and vice chair of research for Orthopaedics and Sports Medicine at the University of Washington in Seattle and a cofounder of State College, PA-based DIApedia, which has commercialized the orthotic design algorithm used in the study. Because it is more expensive to create foot orthoses that incorporate plantar pressure data, Cavanagh and colleagues have been working to persuade Medicare officials of the need to establish a new billing code. The researchers are expecting to hear more in November, he said.

“A change in payment is required based on the evidence of efficacy and cost effectiveness,” he said. “I think we are one of the few disciplines in healthcare that is unaccustomed to making an investment in hardware.”

The second study looked at advanced manufacturing techniques, concluding that personalized foot orthoses created using two different types of additive manufacturing were at least as
effective as standard polypropylene orthoses for improving biomechanics and subjective measures in 15 patients with early rheu­ma­toid arthritis. Each study participant wore all three types of devices, each for seven days in random order. The findings were epublished in July 2013 by Arthritis Care and Research.2

The study also found that outcomes with the devices made using the two additive techniques, fused deposition modeling (FDM) and selective laser sintering (SLS), did not differ significantly from each other. Of the foot orthoses rated by patients as ineffective, none were SLS devices and just three were FDM devices, versus five standard devices.

While FDM is typically done in a clinic, SLS is more often factory-based and utilized by what the researchers call small-to-medium enterprises (SMEs).

“I think this has given the SMEs confidence that they’re headed in the right direction,” said study coauthor Prof Jim Woodburn PhD, FCPodM, interim director of the Institute for Applied Health Research at Glasgow Caledonian University in Scotland, UK, who presented the findings in Chicago.

  1. Ulbrecht JS, Hurley T, Mauger DT, Cavanagh PR. Prevention of recurrent foot ulcers with plantar pressure-based in-shoe orthoses: The CareFUL prevention multicenter randomized controlled trial. Diabetes Care 2014;37(7):1982-1989.
  2. Gibson KS, Woodburn J, Porter D, Telfer S. Functionally optimized orthoses for early rheumatoid arthritis foot disease: A study of mechanisms and patient experience. Arthritis Care Res 2013 Jul 8. [Epub ahead of print]

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