Diabetic foot

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215 Diabetic foot

Instruction

Examine this patient’s legs.

Examine this patient’s feet.

Neuropathic and ischaemic foot presenting together

Examination

• Ulcer on the foot with callosities at pressure points

• Loss of the arch of foot

• Stocking distribution of sensory loss of all modalities

• Loss of dorsalis pedis and/or posterior tibial pulsations.

Proceed as follows:

• Tell the examiner that you would like to:

• check the urine for sugar

• do a simple neurologic examination of the lower extremities involving the use of a 10 g monofilament to test sensation.

• When asked to examine the feet, remember that the evaluation should include assessment of:

• degree of neuropathy (clinically)

• severity of ischaemia (clinically, Doppler, CT angiography)

• bone deformity (clinically, radiograph, MRI)

• infection (local swab, blood culture, radiograph, MRI).

• The common conditions affecting the feet are diabetes and atherosclerosis. Pay particular attention to the pulses and the skin.

Diagnosis

This patient has features of both an ischaemic and neuropathic foot (lesion), which is caused by diabetes mellitus (aetiology); walking is limited by the plantar ulcer (functional status).

Questions

What are the types of diabetic foot?

• Neuropathic foot (Fig. 215.1)

• Ischaemic foot (Fig. 215.2).

Fig. 215.1 The high-risk neuropathic foot: wasting of small muscles, clawing of the toes and marked prominence of the metatarsal heads. There is also ulceration.

(With permission from Andersson, Svardsudd K 1995.)

Fig. 215.2 Ischaemic diabetic foot: exposed tendon at the base of a left foot wound.

(With permission from Auerbach 2007.)

Note: Features of both types often occur together.

Advanced-level questions

What is the pathophysiology of the ischaemic foot?

Occlusive vascular disease involving both microangiopathy and atherosclerosis of large and medium-sized arteries.

Mention a few conditions in which neuropathic ulcers are seen

• Progressive sensory neuropathy

• Tabes dorsalis

• Amyloidosis

How would you manage this patient?

• Patient education: avoid cigarette smoking, inspect the feet daily for blisters, no walking barefoot, avoid tight shoes and avoid cutting toenails straight across. ‘The patient should be advised to take care of his foot as good as his/her face’

• Radiograph of the foot

• Antibiotics

• Removal of necrotic tissue

• Removal of weight bearing and friction from ulcerated areas; use appropriate footwear such as moulded insoles or plaster cast, instant total contact-cast or crutches to avoid weight bearing

• Control hyperglycaemia

• Surgical opinion and arteriography if reconstructive vascular surgery or angioplasty is considered. When irreversible arterial insufficiency occurs, it is often quicker and more humane for the patient to undergo early major amputation rather than be subjected to a series of debilitating conservative procedures

• Hyperbaric oxygen, platelet-derived growth factor and tissue-engineered skin; intermittent negative pressure applied to a wound to stimulate cellular proliferation; electrical stimulation and hydrotherapy.

How would you monitor a diabetic at annual review?

• Eyes: visual acuity, fundoscopy

• Sensory system: touch, pinprick and vibration sense

• Deep tendon reflexes

• Cardiovascular system: BP, peripheral pulses

• Biochemistry: urine and blood sugar, albumin, glycosylated haemoglobin, creatinine.

What is the importance of the Neuropathy Disability Score?

The Neuropathy Disability Score is based in impairment of sensation. A score (for both feet) of ≥6 is predictive of foot ulceration. The annual risk of ulceration is 1.1% if the score is <6 and 6.3% if it is ≥6. A maximum of 5 points can be scored by each foot:

What do you know about measurement of cutaneous pressure perception?

Semmes–Weinstein monofilaments assess sensory perception. Individuals with normal feet can usually feel the 4.17 monofilament (~1 g linear pressure). Patients who cannot feel the 5.07 monfilament (~10 g of linear pressure) before it buckles are considered to have lost protective sensation. A seven-fold increase in the risk of ulceration has been reported in patients insensitive to the 5.07 monofilaments. However, up to 10% of persons who feel the monofilament before it buckles may still have cutaneous breakdown.

Professor Brian Frier, BSc (Hons), MD, FRCPE, FRCPG is a Consultant Physician in general (internal) medicine and diabetes at the Royal Infirmary of Edinburgh and is Honorary Professor of Diabetes in the University of Edinburgh. He graduated from the University of Edinburgh, trained in Scotland, and was a Clinical Research Fellow at the Cornell University Medical Center in New York. Professor Frier was previously a Consultant Physician in the Western Infirmary and Gartnavel General Hospital in Glasgow, Scotland (1982-87). He is currently Vice-President of the Royal College of Physicians of Edinburgh.

Professor Frier’s principal research interest is the pathophysiology of hypoglycaemia in humans with particular relevance to diabetes.

Professor Miles Fisher, Consultant Physician Royal Infirmary Glasgow. He graduated from Glasgow University in 1979. He worked as a research fellow in the Department of Diabetes in Gartnavel General Hospital in the 1980s, where his interests were diabetes and the heart, and hypoglycaemia. He is Vice President of Royal College of Physicians and Surgeons of Glasgow.

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