April 2016

Out on a limb: Ingenuity targets activity

1Limb-JordanaBy Jordana Bieze Foster, Editor

Diabetic foot specialists have a range of options for managing diabetic foot ulcers—from offloading devices to skin substitutes to surgical procedures.

But sometimes the most effective treatment is the one that compels an active patient to simply slow down.

Monitoring and managing patient activity levels was a recurring theme at this year’s Diabetic Limb Salvage (DLS) Conference, held in late March in Washington, DC. Given that this event is primarily about vascular and orthopedic surgical techniques, the fact that the discussion circled back to patient activity levels multiple times underscores its clinical significance.

It’s no secret that the effects of weightbearing—and dynamic weightbearing in particular—undermine the wound healing process in a patient with a diabetic ulcer on the plantar surface of the foot. But, because patients are notoriously noncompliant with instructions to stay off their feet, ulcer healing efforts have focused on designing devices that will offload the ulcer site even under weightbearing conditions. And the total contact cast (TCC) has always been considered the gold standard for offloading because it is associated with better ulcer healing than other offloading techniques.

But experts say offloading is only part of why TCCs are effective. Another reason is that they make it difficult for patients to walk. With a cast on one leg, patients are forced to walk more slowly, with shorter, less frequent steps. This decrease in activity is, essentially, another way of offloading the ulcer.

Lower extremity professionals have long known this to be true, dating back half a century to diabetic foot care pioneer Paul Brand, MD, who died in 2003.

Armed with new ways to monitor patient activity, diabetes experts say it’s time to revisit that aspect of the offloading equation.

“Paul Brand used to say if you could tether people’s feet to alter their gait, you would get effective offloading,” Lawrence A. Lavery, DPM, MPH, a professor of plastic surgery at the University of Texas Southwestern Medical Center in Dallas, said during a DLS presentation.

Now, with the availability of activity monitoring technologies, experts say it’s time to once again start emphasizing that aspect of the offloading equation.

“Activity monitors used to be exotic,” said DLS presenter David G. Armstrong, DPM, MD, PhD, a professor of surgery at the University of Arizona in Tucson, gesturing at his smart phone. “Now they’re things we use every day.”

Hardly limited to virtual pedometers, this new generation of monitoring systems includes instrumented insoles or mats that detect increases in plantar pressure or temperature—both of which are associated with excessive activity—in at-risk patients and wirelessly send that information to clinicians. Armstrong described such systems as being “like OnStar for your body.”

A DLS poster described a study done at the VA Medical Center in Phoenix, AZ, involving a foot mat designed to allow in-home foot temperature monitoring. In patients with recently healed ulcers, the mat detected a temperature difference between the affected and unaffected feet several weeks before the ulcers actually recurred.

A number of questions about such technologies remain unanswered, not the least of which is who will pay for them. But the renewed focus on activity monitoring is one I think Brand would appreciate. It sure beats tethering a patient’s feet together.

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