The Diabetic Foot
AUTHOR: Keith Baxter
What is the Diebetic Foot?
Diabetics are at increased risk of developing foot wounds and is the most common cause of foot ulcers, infection, and amputation. Approximately 25% of diabetics will develop a foot wound in their lifetime.
What are the causes?
Many factors can lead to diabetic foot wounds: diminished foot sensation, altered foot mechanics, decreased sweating (leading to dry skin which is prone to cracking), structural changes in the foot, and peripheral arterial disease (PAD). Diabetics have an increased prevalence of atherosclerosis (the main cause of PAD) which narrows the blood vessels of the leg and within the foot.
What are the symptoms?
One very important feature of the diabetic foot is identifying predisposing factors prior to onset of complications. Diabetics should inspect their feet and shoes regularly searching for signs of skin irritation, abnormal wear and foreign materials. ANY wound needs close attention. This includes skin cracks, blisters, calluses, ulcers, or gangrene (tissue death). An infection may be present if there is foot redness,warmth,swelling or pain, wound drainage, or fevers.
Diagnosis and tests
Before complications arise, diabetics can be screened to see whether they may have neuropathy (decreased pain or pressure sensation). This can be done, for example, by testing vibration sense using a tuning fork. Diabetics can also be screened for the presence of PAD by feeling foot pulses and comparing leg blood and arm blood pressures.
Prevention of foot wounds in diabetics, particularly those with neuropathy, is of paramount importance. Risk factors for PAD should be avoided or treated (e.g. avoid smoking, treat hypertension and high cholesterol). Both feet should be inspected regularly and toenails should be carefully trimmed. Shoes should be professionally fitted and not too tight, and wear patterns closely examined to see whether orthotics would be beneficial. Feet should be cleansed daily followed by application of moisturizing cream. Diabetics should not walk barefoot or bath their feet in hot water.
Non-surgical and medical management
The appearance of a foot wound in a diabetic demands prompt and aggressive attention. An infection should be treated with antibiotics. Pressure in the area of an ulcer should be offloaded. After debridement, appropriate wound care with regular dressing changes and wound inspection should be instituted. In some circumstances, hyperbaric oxygen therapy has shown benefit.
Guidelines for Intervention
All diabetic foot wounds require some degree of intervention. Small, non-infected wounds may just require appropriate dressing care and alterations to the shoe to offload pressure from the affected area. Non-healing, deep, infected, or gangrenous wounds usually require more aggressive care (see surgical and endovascular treatment).
Surgery for a complicated diabetic foot wound may be needed to address the foot wound itself, correct the underlying cause for the wound forming the the first place, and improve the foot environment to maximize the chance of healing. Infected dead tissue around a wound may need to be removed. If the wound is large or the infection is severe, amputation may be necessary. To improve the circulation to the foot, a bypass operation may be recommended. A bypass procedure is performed to route blood around blocked blood vessels. Foot deformities may also need to be surgical corrected to help prevent future wounds from forming.
To open blocked blood vessels and improve the circulation to the foot, sometimes and endovascular treatment option is appropriate. Endovascular techniques involve guiding balloons through blood vessels which are inflated to open blockages. Sometimes a stent is needed to keep a treated blood vessel open. Endovascular treatments are less invasive, but may not be suitable for all types of blocked blood vessels.
When should I see my doctor?
Any diabetic with a foot wound that is not healing should be seen by their doctor. Large, deep, infected wounds or signs of gangrene need prompt attention. You may be referred to see a Vascular Surgeon or foot specialist.
References and Resources
Canadian Diabetes Association: www.diabetes.ca
Mayo clinic: www.mayoclinic.com
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