Post: Diabetic Foot Ulcers: Life-Threatening Issue in Need of Help- David Armstrong, PhD, DPM

On April 16, Medscape featured David Armstrong, PhD, DPM, a podiatric surgeon with Keck Medicine and professor of surgery, on technology to prevent and treat diabetic foot ulcers.

Kathleen Doheny

April 16, 2024

The photo of the patient’s foot, sent from his campsite, included a cheeky note: “I remember you telling me that getting in trouble doing something was better than getting in trouble doing nothing. This lets me get out there and know that I have feedback.”

The “this” was the patient’s “foot selfie,” an approach that allows patients at a risk for diabetic foot ulcers (DFUs) to snap a picture and send it to their healthcare providers for evaluation.

This particular patient had an extensive history of previous wounds. Some had essentially kept him house-bound in the past, as he was afraid to get another one.

This time, however, he got an all-clear to keep on camping, “and we scheduled him in on the following Tuesday [for follow-up],” said the camper’s physician David G. Armstrong, DPM, MD, PhD, professor of surgery and neurological surgery, USC Keck School of Medicine, Los Angeles.

photo of David Armstrong
Dr David G. Armstrong

Armstrong is one of the researchers evaluating the concept of foot selfies. It’s a welcome advance, he and others said, and has been shown to help heal wounds and reverse pre-ulcer lesions. Research on foot selfies continues, but much more is needed to solve the issue of DFUs, diabetic foot infections (DFIs), and the high rates of reinfection, experts know.

Worldwide, about 18.6 million people have a DFU each year, including 1.6 million in the United States. About 50%-60% of ulcers become infected, with 20% of moderate to severe infections requiring amputation of the limb. The 5-year mortality rate for DFUs is 30%, but it climbs to 70% after amputation. While about 40% of ulcers heal within 12 weeks, 42% recur at the 1-year mark, setting up a vicious and costly cycle. Healthcare costs for patients with diabetes and DFUs are five times as high as costs for patients with diabetes but no DFUs. The per capita cost to treat a DFU in America is $17,500.

While the statistics paint a grim picture, progress is being made on several fronts:

  • US Food and Drug Administration (FDA) guidance on the development of drugs for DFUs, under evaluation, is forthcoming.
  • New treatments are under study.
  • A multidisciplinary team approach is known to improve outcomes.

Anatomy of a DFU

When neuropathy develops in those with diabetes, they no longer have what Armstrong calls the “gift” of pain perception. “They can wear a hole in their foot like you and I wear a hole in our sock or shoe,” he said. “That hole is called a diabetic foot ulcer.”

A DFU is an open wound on the foot, often occurring when bleeding develops beneath a callus and then the callus wears away. Deeper tissues of the foot are then exposed.

About half of the DFUs get infected, hence the FDA guidance, said Armstrong, who is also founding president of the American Limb Preservation Society, which aims to eliminate preventable amputations within the next generation. Every 20 seconds, Armstrong said, someone in the world loses a leg due to diabetes.

FDA Guidance on Drug Development for DFIs

In October, the FDA issued draft guidance for industry to articulate the design of clinical trials for developing antibacterial drugs to treat DFIs without concomitant bone and joint involvement. Comments closed on December 18. Among the points in the guidance, which is nonbinding, are to include DFIs of varying depths and extent in phase 3 trials and ideally to include only those patients who have not had prior antibacterial treatment for the current DFI.

According to an FDA spokesperson, “The agency is working to finalize the guidance. However, a timeline for its release has not yet been established.”

The good news about the upcoming FDA guidance, Armstrong said, is that the agency has realized the importance of treating the infections. Fully one third of direct costs of care for diabetes are spent on the lower extremities, he said. Keeping patients out of the hospital, uninfected, and “keeping legs on bodies” are all important goals, he said.

Pharmaceutical firms need to understand that “you aren’t dealing with a normal ulcer,” said Andrew J.M. Boulton, MD, professor of medicine at The University of Manchester and physician consultant at the Manchester Royal Infirmary, Manchester, England, and a visiting professor at the University of Miami. For research, “the most important thing is to take account of off-loading the ulcers,” he said. “Most ulcers will heal if put in a boot.”

Boulton, like Armstrong, a long-time expert in the field, contended that pharma has not understood this concept and has wasted millions over the last three decades doing studies that were poorly designed and controlled.

Treatments: Current, Under Study

Currently, DFIs are treated with antimicrobial therapy, without or without debridement, along with a clinical assessment for ischemia. If ischemia is found, care progresses to wound care and off-loading devices, such as healing sandals. Clinicians then assess the likelihood of improved outcomes with revascularization based on operative risks and distribution of lower extremity artery disease and proceed depending on the likelihood. If osteomyelitis testing shows it is present, providers proceed to wound debridement, limb-sparing amputation, and prolonged antimicrobials, as needed.

More options are needed, Armstrong said.

Among the many approaches under study:

  • DFUs can be accurately detected by applying artificial intelligence to the “foot selfie” images taken by patients on smartphones, research by Armstrong and others has found.
  • After a phase 3 study of gene therapy for DFUs originally intending to enroll 300 subjects was discontinued because of slow patient recruitment, an interim analysis was conducted on 44 participants. It showed a positive trend toward wound closure in the group receiving the injected gene therapy, VM202 (ENGENSIS), in their calf muscles. VM202 is a plasmid DNA-encoding human hepatocyte growth factor. While those in both the intervention and placebo groups showed wound-closing effects at month 6, in 23 patients with neuro-ischemic ulcers, the percentage of those reaching complete closure of the DFU was significantly higher in the treated group at months 3, 4, and 5 (P = .0391, .0391, and .0361, respectively). After excluding two outliers, the difference in months 3-6 became more significant (P = .03).
  • An autologous heterogeneous skin construct closed more DFUs than standard care after 12 weeks — 70% vs 34% (P = .00032). Of the 100 participants randomized, 50 per group, 42% of the treatment group and 56% of the control group experienced adverse events, with eight withdrawn due to serious adverse events (such as osteomyelitis).
  • A micro water jet device closed more refractory DFUs over a 16-week study than standard sharp debridement, with 65% of water-treated ulcers healed but just 42% of the standard care group (P = .021, unadjusted).
  • Researchers from UC Davis and VA Northern California Healthcare are evaluating timolol, a beta adrenergic receptor blocker already approved for topical administration for glaucoma, as a way to heal chronic DFUs faster. After demonstrating that the medication worked in animal models, researchers then launched a study to use it off-label for DFUs. While data are still being analyzed, researcher Roslyn (Rivkah) Isseroff, MD, of UC Davis and VA, said that data so far demonstrate that the timolol reduced transepidermal water loss in the healed wounds, and that is linked with a decrease in re-ulceration.

The Power of a Team

Multidisciplinary approaches to treatment are effective in reducing amputation, with one review of 33 studies finding the approach worked to decrease amputation in 94% of them. “The American Limb Preservation Society (ALPS) lists 30 programs,” said Armstrong, the founding president of the organization. “There may be as many as 100.”

Team compositions vary but usually include at least one medical specialty clinician, such as infectious disease, primary care, or endocrinology, and two or more specialty clinicians, such as vascular, podiatric, orthopedic, or plastic surgery. A shoe specialist is needed to prescribe and manage footwear. Other important team members include nutrition experts and behavioral health professionals to deal with associated depression.

Johns Hopkins’ Multidisciplinary Diabetic Foot and Wound Service launched in 2012 and includes vascular surgeons, surgical podiatrists, endocrinologists, wound care nurses, advanced practice staff, board-certified wound care specialists, orthopedic surgeons, infection disease experts, physical therapists, and certified orthotists.

“This interdisciplinary care model has been repeatedly validated by research as superior for limb salvage and wound healing,” said Nestoras Mathioudakis, MD, codirector of the service. “For instance, endocrinologists and diabetes educators are crucial for managing uncontrolled diabetes — a key factor in infection and delayed wound healing. Similarly, vascular surgeons play a vital role in addressing peripheral arterial disease to improve blood flow to the affected area.”

photo of Nestoras Mathioudakis
Dr Nestoras Mathioudakis

“Diabetic foot ulcers might require prolonged periods of specialized care, including meticulous wound management and off-loading, overseen by surgical podiatrists and wound care experts,” he said. “In cases where infection is present, particularly with multidrug resistant organisms or when standard antibiotics are contraindicated, the insight of an infectious disease specialist is invaluable.”

While the makeup of teams varies from location to location, he said “the hallmark of effective teams is their ability to comprehensively manage glycemic control, foot wounds, vascular disease, and infections.”

The power of teams, Armstrong said, is very much evident after his weekly “foot selfie rounds” conducted Mondays at 7 AM, with an “all feet on deck” approach. “Not a week goes by when we don’t stop a hospitalization,” he said of the team evaluating the photos, due to detecting issues early, while still in the manageable state.

Teams can trump technology, Armstrong said. A team of just a primary care doctor and a podiatrist can make a significant reduction in amputations, he said, just by a “Knock your socks off” approach. He reminds primary care doctors that observing the feet of their patients with diabetes can go a long way to reducing DFUs and the hospitalizations and amputations that can result.

Mathioudakis and Isseroff reported no disclosures. Boulton consults for Urgo Medical, Nevro Corporation, and AOT, Inc. Armstrong reported receiving consulting fees from Podimetrics; Molnlycke; Cardiovascular Systems, Inc.; Endo Pharmaceuticals; and Averitas Pharma (GRT US).


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