ABC of wound healing: Diabetic foot ulcers

Diabetic foot ulcers can be divided into two groups: those in neuropathic feet (so called neuropathic ulcers) and those in feet with ischaemia often associated with neuro-pathy (so called neuroischaemic ulcers). The neuropathic foot is warm and well perfused with palpable pulses; sweating is diminished, and the skin may be dry and prone to fissuring. The neuroischaemic foot is a cool, pulseless foot; the skin is thin, shiny, and without hair. There is also atrophy of the subcutaneous tissue, and intermittent claudication and rest pain may be absent because of neuropathy. The crucial difference between the two types of feet is the absence or presence of ischaemia. The presence of ischaemia may be confirmed by a pressure index (ankle brachial pressure index <1). As many diabetic patients have medial arterial calcification, giving an artificially raised ankle systolic pressure, it is also important to examine the Doppler arterial waveform. The normal waveform is pulsatile with a positive forward flow in systole followed by a short reverse flow and a further forward flow in diastole, but in the presence of arterial narrowing the waveform shows a reduced forward flow and is described as “damped.” Neuropathic ulcers usually occur on the plantar aspect of the foot under the metatarsal heads or on the plantar aspects of the toes. The most common cause of ulceration is repetitive mechanical forces of gait, which lead to callus, the most important preulcerative lesion in the neuropathic foot. If allowed to become too thick, the callus will press on the soft tissues underneath and cause ulceration. A layer of whitish, macerated, moist tissue found under the surface of the callus indicates that the foot is close to ulceration, and urgent removal of the callus is necessary. If the callus is not removed, inflammatory autolysis and haematomas develop under …