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Diabetic foot ulcer

Author: Vanessa Ngan, Staff Writer, 2003.

Diabetic foot ulcer — codes and concepts

What is a diabetic foot ulcer?

Diabetic foot ulcers are sores on the feet that occur in 15% of diabetic patients sometime during their lifetime. The risk of lower-extremity amputation is increased 8-fold in these patients once an ulcer develops. They occur in type 1 and type 2 diabetes mellitus. The average duration of diabetes before ulceration is > 10 years.

What causes a diabetic foot ulcer?

Neuropathic and vascular complications of diabetes cause a diabetic foot ulcer.

Nerve damage due to diabetes causes altered or complete loss of feeling in the foot and leg. This is known as peripheral neuropathy. Pressure from shoes, cuts, bruises, or any injury to the foot may go unnoticed. The loss of protective sensation stops the patient from being warned that the skin is being injured and may result in skin loss, blisters and ulcers, and sometimes to underlying bone fracture. Neuropathy can also lead to an arthropathy (a Charcot joint) and deformities such as an equinus contracture (inability to flex the ankle joint to lift the toes).

Vascular disease is also a major problem in diabetes and mainly affects tiny blood vessels feeding the skin (microangiopathy). In this situation, a doctor may find normal pulses in the feet because the arteries are unaffected. However, other diabetic patients may also have narrowed arteries so that no pulse can be found in the feet (ischaemia). The lack of healthy blood flow may lead to ulceration. Wound healing is also impaired.

Vascular disease is aggravated by smoking. End-stage renal disease is another risk factor for foot ulceration.

What are the signs and symptoms of diabetic foot ulcer?

It is not unusual for patients to have had diabetic foot ulcers for some time before presenting to a health professional because they are frequently painless.

Depending on the severity, a diabetic foot ulcer may be rated between 0 and 3.

0: at risk foot with no ulceration
1: superficial ulceration with no infection
2: deep ulceration exposing tendons and joints
3: extensive ulceration or abscesses

Tissue around the ulcer may become black due to the lack of healthy blood flow to the foot. In severe cases, partial or complete gangrene may occur.

Skin complications of diabetes

People with diabetes are also very prone to secondary infection of the ulcer (wound infection), sinus formation, surrounding skin (cellulitis) and underlying bone (osteomyelitis).

How can the diabetic foot ulcer be prevented?

Management of diabetic foot ulcer is primarily aimed at prevention. Strategies include:

  • Optimise diabetes control to reduce neuropathic and vascular complications
  • Smoking cessation
  • Preventive skin and nail care: examine the skin of both feet carefully and trim toenails regularly.
  • Prompt treatment of athlete's foot, cracked heel or dermatitis.
  • Comfortable footwear: properly fitting soft shoes or made-to-measure insoles
  • Exercises and physiotherapy
  • Regular and frequent foot examination.

What is the treatment of diabetic foot ulcer?

Once an ulcer has developed, the cause should be determined. Is it neuropathic, vascular or both?

  • Neuropathic ulcer must be protected from further injury until they heal, and strenuous efforts must be made to avoid another ulcer by wearing the correct footwear.
  • A vascular or ischaemic ulcer should be evaluated by a vascular surgeon to determine the extent of damage and whether surgery is necessary; in severe cases, this may entail partial amputation of a toe, foot or limb.
  • Radiology is also useful to evaluate osteomyelitis.

Whatever the cause of the ulcer, any dead tissue of the surface should be debrided (removed), the wound cleansed with antiseptic or superoxide solution, and synthetic wound dressings applied to ensure a moist environment. Honey dressings may also be useful. Expert advice should be obtained, as the best dressing will depend on the type of ulcer and stage of healing. 

Infection should be prevented with careful wound care and regular inspection. Antibiotics may be prescribed if there is significant infection resulting in cellulitis or osteomyelitis. 

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