A 50-year-old man with type 1 diabetes of 30 years' duration underwent amputation of the second ray of his right foot for wet gangrene. At discharge from hospital he was reluctant to wear special shoes. After the foot healed he developed heavy callus over his 1st and 4th metatarsal heads. Speckles of blood within the callus indicated a preulcerative state (Fig. 3.6). He agreed to wear bespoke shoes after the significance of the blood within the callus was explained. The orthotists supplied cradled insoles with poron sinks in bespoke shoes, callus was debrided at monthly intervals, and he did not develop an ulcer.
• Speckles of blood within callus indicate that an ulcer is imminent
• Patients with ray amputations should be strongly advised to accept bespoke shoes and taught to return immediately if speckles of blood are observed within their callus
• Regular debridement of callus and bespoke shoes can prevent neuropathic ulcers.
Podiatric removal of callus
• Callus should be removed with a scalpel held by the operator's dominant hand
• The fingers of the operator's other hand should stretch the tissue being operated on to maintain good skin tension and ensure even removal of callus
• The foot should not be soaked prior to callus removal by scalpel debridement. The operator needs visual and tactile clues to guide him as to the amount of callus that can be safely removed. Callus contains more moisture in its deeper levels, closer to the epidermodermal junction, and if the skin and callus are macerated by soaking then valuable tactile clues as to the depth the operator has reached are lost
• Patients who develop callus on pressure points need regular treatment and careful follow-up if ulceration is to be prevented
• Speed of regro wth of callus varies and treatment periods must be individually planned
• Formation of callus is a warning that dangerously high mechanical forces are acting on the stage 2 foot, and every effort should be made to achieve effective mechanical control through footwear adaptation and lifestyle changes
• Patients should be taught the danger signs that callus is becoming preulcerative
■ Patients who fail to keep an appointment for callus removal should be recalled.
In countries where there is no tradition of podiatry, nurses and physicians can learn podiatric techniques (Fig. 3.7). To learn precision and gain manual dexterity they should try first to remove the skin from an orange without removing any white pith, and practice paring wax from a candle. The first 'patients' they remove callus from should be family or colleagues, and they can then move on to practising on non-diabetic patients with no risk factors before they treat high-risk patients.
Removal of callus by patients' carers
Patients should never cut their callus off, or use propri-
etary corn or callus removers. These contain strong acids and can damage the skin, allowing infection to enter the foot.
For diabetic foot patients who are unable to reach a health-care professional, the following procedure can be undertaken by a carer, family member or friend to reduce the callus.
• Soak the foot in a bowl of warm water containing a handful of salt for 15 min
• Rub a pumice stone or a piece of Scotchbrite (nylon kitchen scouring pad) over the area of callus to reduce the thickness
• Tape a piece of clean gauze over the area and keep it covered, and walk as little as possible for 48 h
• Observe the foot carefully for discharge or tissue breakdown. If these develop the foot should be shown to a health-care professional as soon as possible.
The authors are aware that the above advice is controversial. It is delivered in the belief that preventive foot care delivered by people who have been taught safe techniques and know the importance of not breaking the skin of the high-risk foot is better than no foot care at all.
In addition, correct nail cutting techniques (see Chapter 2) should be taught to stage 2 patients and their families if they live in isolated areas and are unable to obtain sufficiently frequent foot care from professionals.
Fissures are a complication of dry neuropathic skin. Regular application of emollient helps to prevent fissures. The edges of deep fissures should be cleared of callus and the crevice can be held together with Steri-strips to speed healing (Fig. 3.8a-c). Patients who are prone to heel fissures should avoid backless footwear.
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