A 67-year-old man with type 2 diabetes which had not previously been diagnosed, developed what he took to be a blood blister on his left hallux. The lesion was not painful, he felt well, and he did not seek treatment until he noticed an unpleasant odour and went to casualty. The toe was infected and necrotic. Pedal pulses were bounding. His vibration perception threshold was 45 volts (Fig. 6.3). He underwent amputation of the hallux and the foot healed in 4 months. Three weeks after he was discharged he re-presented at the diabetic foot clinic with a rockerbottom Charcot foot. This was treated in a total-contact cast for 6 months and there was no progression of the deformity.
• Necrosis may be mistaken for blood blisters by patients and health-care professionals
• In patients with neuropathy, necrosis may not be painful
• Patients with neuropathy who undergo surgery for necrosis may develop Charcot's osteoarthropathy
• Patients with type 2 diabetes may have undiagnosed diabetes for many years and develop severe complications including neuropathy and foot ulceration by the time of diagnosis
• In wet necrosis, the tissues are grey or black, moist and often malodorous. Adjoining tissues are infected and
Fig. 6.3 This necrotic toe in a previously undiagnosed diabetic patient was thought by him to be a blood blister.
pus may discharge from an ulcerated area between necrosis and viable tissue. There may be no clear demarcation line between necrosis and viable tissue and it may be difficult to predict exactly which areas of tissue are viable until debridement has been performed
• Once infection is established, necrosis can develop within a few hours.
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Diabetes is a disease that affects the way your body uses food. Normally, your body converts sugars, starches and other foods into a form of sugar called glucose. Your body uses glucose for fuel. The cells receive the glucose through the bloodstream. They then use insulin a hormone made by the pancreas to absorb the glucose, convert it into energy, and either use it or store it for later use. Learn more...