Trauma: The Unrecognized Trigger for Diabetic Foot Ulcers

Most medical providers are aware of the 3 types of neuropathies that can impact the patient with diabetes: sensory, motor and autonomic. It is important to understand that even though people with diabetes may experience neurological and vascular changes, these changes are not the only contributors to diabetic foot ulcers (DFUs). Instead, look at this as the conditions of diabetic sensory neuropathy, combined with peripheral arterial disease (PAD), set the stage for the development of a foot ulcer. Then, a triggering event of mechanical, chemical, or thermal trauma commences the presence of the ulcer. Understanding this concept is critical and offers an opportunity to educate patients and prevent DFUs.
 
Let’s take a closer look at these traumas and how we might prevent them.
 
Mechanical trauma (Figure 1) is caused by a wide variety of events that all share one common outcome; which is that the integrity of the skin is broken. Examples of mechanical trauma may include:

• improperly fitted shoes or improperly applied socks;
• a foreign object in the shoe like a key or coin (I once found a pair of glasses in a patient’s shoes and she thanked me as she thought she had lost them!);
• walking barefoot and stepping on a foreign body like a piece of glass or insulin needle;
• dropping an object on the unprotected foot, like a food can;
• or bumping the foot on the door frame at night while walking barefoot to the bathroom.

Chemical trauma (Figure 2) is the result of exposure of the foot to any chemical that can damage the skin. In my experience, a common chemical responsible for the development of a DFU is salicylic acid. This chemical is found in over-the-counter medications used to treat corns, calluses, warts, and ingrown toenails. Salicylic acid has the property of destroying tissue, usually painlessly. However, use of this medication—by a patient with diabetes can result in the typical white acid burn to the tissues and an ulcer.
 
Thermal trauma (Figure 3) is associated with exposure of the foot to abnormal temperatures of either heat or cold.
 
Heat: Two common forms of thermal trauma caused by abnormal exposure to heat are environmental and self-inflicted exposure. Exposure of the feet to hot water or walking barefoot, especially on hot sidewalks or asphalt driveways are environmental forms of heat trauma. Since people with diabetes may suffer from some degree of PAD, they may relate that they feel their feet are cold. In an attempt to warm their feet they may expose them to heat sources such as heating pads, hot water bottles, or even open fires, fireplaces, heating registers, or space heaters. This self-inflicted abnormal exposure to heat can lead to development of a thermal burn and an ulcer, possibly undetected due to neuropathy.
 
Cold: Exposure to cold is another form of thermal trauma that can lead to numbness, cramps in the lower legs, burning or tingling sensations, tenderness of the foot, red or blue discoloration of the skin, and ultimately a break in the skin. Other damage to the feet caused by cold temperatures includes chilblains, frostbite, and gangrene.

Opportunities to Prevent a Diabetic Foot Ulcer

Statistics indicate that 25% of people with diabetes will have a foot ulcer in their lifetime. The cost of treating these wounds in 2022 was close to $20,000.¹ An often-unrecognized benefit of healing a DFU is prevention of an amputation. So, it’s easy to see how important it is to prevent a DFU for both quality-of-life issues and to reduce the cost of healthcare.

Preventing Triggering Trauma to the Feet

Now that we have reviewed the 3 types of neuropathies, that combined with PAD and the types of triggering events, can lead to a DFU, there are obvious opportunities for education of patients on prevention. How do you educate your patients about avoiding these types of traumas? Below, I share some of my insights on key points to cover.
 
Preventing mechanical trauma can be minimized, at least in part, by wearing shoes. Shoes are ideally meant to cover, protect, and support the foot. I share that people with diabetes should inspect their shoes for foreign bodies before putting them on and keep their shoes on anytime they are out of bed. The key to preventing mechanical trauma to the foot, in my experience, is to have two pairs of properly fitted shoes (diabetic or custom molded, when indicated, one to wear and one as a backup) and to use well fitted and applied socks made from natural fibers like cotton or wool to protect the foot from any type of mechanical trauma.
 
Preventing chemical trauma, in my experience, is rather straightforward. For these at-risk patients, it makes sense to avoid any over-the-counter topical mediation that contains salicylic acid, and to educate patients on what types of products could contain this component.
 
Preventing thermal trauma may be a matter of checking bath water with a thermometer or with the hand to be sure the water is not too hot. Walking barefoot at any time is not acceptable, and shoes may also contribute to protecting the feet from thermal trauma. Using appropriate socks and shoes can keep the feet warm and prevent them from exposure to abnormally cold temperatures. We as podiatrists know the value of appropriate shoe gear across a variety of patient populations and this is certainly no exception.
 
With this information you now have the opportunity to educate patients with diabetes about sensory neuropathy, PAD and triggering trauma events of mechanical, chemical, or thermal trauma and how to prevent DFUs. Sharing our knowledge with our patients is paramount, and in this new year, take the time to consider what information you share with patients and how—it could truly make all the difference.

Dr. Hinkes is President and Chief Medical Officer of ePrevenir, Inc. He is board certified by the American Board of Foot and Ankle Surgery and is a Fellow of the American College of Foot and Ankle Surgeons and the American Professional Wound Care Association. He is the author of “Healthy Feet for People With Diabetes” and “Keep the Legs You Stand On,” available at www.amazon.com.

Reference
1.    Rice JB, Desai U, Cumminga AKG, Birnbaum HG, Skornicki M, Parsons NB. Burden of diabetic foot ulcers for medicare and private insurers. Diabetes Care. 2014; 37(3):651–8.

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