Watch Your Step

 Watch Your Step

By Peter Galvin, MD

More than 550 million people worldwide and 37 million people in the U.S. have diabetes. Of these, approximately 34% of people with type 1 or 2 diabetes will develop a foot ulcer during their lifetime. This amounts to 18.6 million people worldwide and 1.6 million people in the U.S. each year. If left untreated, diabetic foot ulcers can progress to soft tissue infection, gangrene, and limb loss. About half of those with diabetic foot ulcers also have arterial disease of the lower extremities. About 50% of these ulcers become infected, with up to 20% requiring hospitalization, and between 15% and 20% lead to lower limb amputation. The direct costs of treating diabetic foot ulcers in the U.S. are estimated to be $9 billion to $13 billion annually. Sadly, people with diabetic foot ulcers have a 5-year mortality rate of 30%, with the 5-year rate for those with an above-foot amputation greater than 70%. And 34% of those with a healed diabetic foot ulcer will develop another one within one year.

These ulcers develop due to diabetic sensory, motor, and autonomic neuropathy. In other words, because these people have numb feet, they do not sense pain from a developing foot ulcer and are not aware of its existence. Because of the neurological issues in diabetic feet, calluses often form in areas subject to pressure from standing and walking (i.e., the bottom of the toes and forefoot). With repeated pressure and ground contact, hemorrhage develops under the callus, causing an ulcer to form. This pressure may be low, as from tight of poorly fitting shoes, or high, such as stepping on a sharp object causing direct mechanical damage.

There are numerous classification systems for diabetic foot ulcers, the most common of them being the Wound, Ischemia (lack of blood flow), and Foot Infection system, known as the Wifi (seriously) classification system. Wifi scores of 1, 2, 3, and 4 correspond to 1-year amputation rates of 0%, 8%, 11%, and 38%. It is not unusual for an infected foot ulcer to infect the underlying bone, a condition called osteomyelitis, which is extremely difficult to treat because bones have no blood circulation, and the presence of osteomyelitis almost guarantees that amputation will be necessary.

Treatment usually involves antibiotics and debridement, a procedure that removes dead or infected tissue and allows viable tissue to heal. Guidelines usually recommend serial debridement, usually weekly or bi-weekly. One study of over 150,000 patients found that weekly debridement resulted in a significant increase in healing (55% to 28%) as compared to those who had less frequent debridement. Another mainstay of treatment is off-loading or removing pressure on the ulcer either by use of a cast or special boot. Dressings are also used and need to provide a moist environment to promote skin growth without causing maceration or softening of the skin. Other methods of treatment include hyperbaric oxygen therapy and negative pressure wound therapy (i.e., wound vacs). If the patient has arterial disease as well, that must be addressed, usually by a vascular specialist.

People with diabetes need to pay frequent visits to a podiatrist, especially if they have diabetic neuropathy. Also, they should never, ever walk on bare feet, even at home, and wear properly fitting shoes.

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