Diabetic Feet & Foot Ulceration

SEE ALSO

Step By Step to Healthy Feet

Footcare

Treatment of Diabetic Feet

The nature of the problem

• 5-10% of the population will have foot ulceration in their lifetime
• 1-2% of Diabetics will undergo lower limb amputation in their lifetime

The reasons behind ulceration occurring in the feet of diabetic patients are a) Neuropathy (lack of sensation) and b) Ischemia (lack of blood supply).

Some feet are more neuropathic than ischemic and some vice versa. Most ulcerated diabetic feet have a combination of both.

The neuropathy may be of 3 types

• Peripheral neuropathy -causing a lack of sensation leading to lack of awareness of trauma caused by foreign bodies, footwear ect.
• Autonomic neuropathy- leading to lack of sweating and dry skin thus predisposing to cracked skin.
• Motor neuropathy- leading to weakness in small muscles of the foot, causing claw toes and other foot deformities.

Neuropathy combined with a lack of blood flow (ischemia) leads to ulceration.

Clinical features of diabetic feet.

Wagner's classification of diabetic foot lesions

Diabetic feet

Impaired sensation in the foot leads to skin breakdown and ulceration over bony areas, this is a called a neuropathic ulcer

Neuropathic ulcer in a foot with impaired sensation

What are "diabetic feet"?

Diabetic patients are prone to ulceration and infection of the foot which may progress to tissue necrosis requiring amputation.  This is due to a combination of vascular disease and neuropathy.

Why do diabetic patients develop foot problems?

Diabetes impairs the function of the nerves and blood vessels supplying the feet.  This makes them prone to small cuts and pressure ulcers which allow infection to enter and spread through the foot.

Sensory neuropathy robs the diabetic foot of the protective mechanism of pain allowing ulceration to develop in response to minor trauma or rubbing.

Autonomic neuropathy reduces sweating and opens arteriovenous shunts in the foot.  The diabetic foot is typically warm, may have strong pedal pulses and dry, cracked skin.  The skin fissuring allows entry of bacteria causing localised infection.

Motor neuropathy causes wasting of the small intrinsic muscles of the foot with collapse of the longitudinal and transverse arches.  Abnormal pressure areas then develop which progress to ulceration.

Atherosclerosis in diabetics develops at a much younger age and is more extensive and distal.  It is not uncommon for a diabetic to have a critically ischaemic foot in the presence of a normal popliteal pulse due to occlusion of the crural arteries.  In addition to disease of the major arteries, the capillary basement membranes thicken, impairing oxygen diffusion to the tissues of the foot.

How are diabetic foot problems treated and avoided?

Management is aimed at prevention by careful foot care.  Good diabetic control helps reduce the severity of foot complications.  There is no specific treatment for neuropathy.  Localised infections should be treated with debridement (surgical removal of infected tissue)  Plain X-rays may show evidence of osteomyelitis (bone infection) and MRI is an accurate way of defining the extent of infection in the foot. 

The outcome for patients with diabetic foot problems is greatly improved by multidisciplinary team-working including diabetes specialist, vascular surgeon, radiologist, and microbiologist.  After treatment, ongoing care with a specialist podiatrist and surgical appliance technician to ensure good footwear are beneficial.

Procedures to improve blood flow for diabetic feet

It is crucial to maximise the blood flow into the foot.  Angioplasty works quite well for the larger arteries but is less reliable for the small arteries around the ankle.  Here, bypasses using microsurgical techniques are highly effective at promoting blood flow into the foot to aid healing of wounds.