Diabetic Foot
by Dr Panayiotopoulos, Consultant Vascular and General Surgeon Essex.

1. What is diabetic foot?

Diabetes, apart from blindness and renal failure causes arterial disease, which most commonly affects the feet. The two main features of diabetic foot are neuropathy [nerve degeneration] and ischaemia [inadequate blood supply to the tissues], both of which predispose to infection and tissue necrosis. However, the majority of patients do not develop diabetic foot!

In the UK [East Anglia] diabetic patients form the largest proportion of admissions and daily occupied beds while in the USA diabetes accounts for 50-75% of all non-traumatic major amputations. 20-30,000 amputations per year are performed.

2. What is the mechanism of diabetic foot?

There are three interrelated factors: neuropathy, ischaemia and infection which often coexist.

Neuropathy causes degeneration of the nerve fibres with loss of the sensation of pain and temperature as well as light touch and vibration. Later, the motor fibres are affected, resulting in wasting and weakness of intrinsic muscles of feet, deformity, claw toes, abnormal weight distribution and callus formation. There is also absence of sweating, skin dryness, cracks and fissures.

The loss of pain and temperature sensation may lead to mechanical damage [tight shoes, penetrating injuries from nail cutting], thermal injuries [bathing in hot water, hot water bottle, feet too close to fire/radiator] and chemical injuries [corn plasters etc.]

Ischaemia is caused by calcification and narrowing of the small vessels but the large vessels in the leg may also be affected.

Due to all these changes plus the presence of hyperglycaemia infections are extremely common and are caused by a variety of micro-organisms.

Combination of all these factors may lead to skin ulceration and then precipitate a vicious cycle between infection and further ischaemia.

3. What is a neuropathic ulcer?

Typically a neuropathic diabetic ulcer is painless, is surrounded by callus, is circular and punched out, extends deep to the bone and develops in areas of high pressure, like the metatarsal heads, the tips of the toes and the sides of the foot.

4. What does management involve?

n    Remove callus. The chiropodist can pare it with a scalpel and allow fluid to drain.

n   Eradicate infection. If it is superficial, oral antibiotics and daily dressings to ulcer may suffice. If the infection is more severe and cellulitis develops, you should rest and elevate your legs. In most cases you will be admitted in the hospital for intravenous antibiotics and blood swabs [cultures] plus proper control of your diabetes. If there is necrotic tissue it should be debrided and if there is an abscess it should be drained

n   Reduce weight-bearing forces. Neuropathic ulcers often take weeks or months to heal and the only way to ensure healing is to remove weight and friction from the ulcerated area. Bed rest, foam padding and soft dressings are helpful.

n   Shoe modification. As infection is clear and the ulcer is healing, proper shoes are necessary to avoid pressure on the feet and prevent secondary ulcerations. Your chiropodist will help you with this.

5. How should I look after my feet?

Foot care is a necessity for people with diabetes. The following are general instructions:

n    Do not walk barefoot

n    Wash your feet daily with warm but not hot water. Dry well between the toes.

n    Check your feet daily for skin cracks or blisters. You should use a mirror to look at the soles and toes.

n    Check that your shoes are not too tight or too loose. Wear new shoes only for short periods of time. Check inside your shoes for any loose object or roughness on the insole before you put them on.

n    Take good care when you cut your toe-nails. Avoid any injury. If you can’t do it properly, get the chiropodist to cut them.

n    Do not sit close to fires or radiators and do not have a hot water bottle in the bed.

n    Change socks or stockings daily. These should be loose fitting and in cold weather wear woollen ones.

n    Do not use corn plasters.

n    Visit your chiropodist regularly.

6. What is a neuroischaemic foot?

Ischaemia in a diabetic foot is caused by atherosclerosis, which is more common in people with diabetes than other patients. Apart from the neuropathic foot changes already described previously, another factor is added, poor blood supply due to narrowing or blockages of the more central vessels that bring blood to the foot. Most patients have had usually suffered from intermittent claudication [pain on walking or foot numbness on walking]. This may be later followed up by rest pain, ulceration and gangrene.

Management should be conservative for small and shallow ulcers, less than 4 weeks old.  A combination of antibiotics, treatment of heart failure, proper footwear and chiropody, abstinence from smoking, weight loss and control of diabetes may suffice.

For larger or chronic ulcers and gangrene surgical treatment may be necessary.

n    If there are pulses palpable on the foot, surgical debridement of necrotic tissues, drainage of abscess and ray foot or toe amputation may be tried.

n    If the ankle pulses are not palpable, further tests are needed, including non-invasive assessment [ultrasounsd] & arteriography. If these tests show that some type of intervention is possible then angioplasty or bypass may be performed. If intervention impossible, then the only options are sympathectomy [improves blood supply to the skin], spinal cord stimulation [to control pain] or drug infusion [prostacyclyn].

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Please note:
A written referral from a general practitioner is helpful but is not essentially required in order to make an appointment to see a consultant specialist.