Definition
The term diabetic foot refers to a spectrum of foot disorders ranging from superficial cellulitis to ulceration and gangrene occurring in people with diabetes mellitus (DM) as a result of peripheral neuropathy or ischaemia, or both.
Key Points
- Prevention is all important with diabetic feet.
- All infections should be treated aggressively to reduce the risk of tissue loss.
- Osteomyelitis is frequently present in the phalanges or metatarsals.
- Treat major vessel POVD as normal – improve ‘inflow’ to the foot.
- Limb loss is a significant risk in patients with diabetic foot ulcers.
Pathophysiology
Three distinct processes lead to the problem of the diabetic foot:
- Ischaemia: macro- and microangiopathy. Higher incidence of atherosclerosis with DM.
- Neuropathy: sensory, motor and autonomic – multifactorial in origin.
- Sepsis: the glucose-saturated tissue promotes bacterial growth.
Clinical Features
Neuropathic Features
- Sensory disturbances – loss of vibratory and position sense.
- Trophic skin changes.
- Plantar ulceration.
- Degenerative osteoarthropathy (Charcot’s joints) – occurs in 2% of DM patients.
- Pulses often present.
- Sepsis (bacterial/fungal).
Ischaemic Features
- Rest pain.
- Painful ulcers over pressure areas.
- History of intermittent claudication.
- Absent pulses.
- Sepsis (bacterial/fungal).
Investigations
- FBC: leucocytosis.
- Serum glucose and gylcosylated Hb (HbA1c): diabetic control may be poor due to sepsis.
- Non-invasive vascular tests: ABI, segmental pressure, digital pressure. ABI may be falsely elevated due to medial sclerosis. Digital pressures more accurate in patients with DM.
- X-ray of foot or CT/MRI may show osteomyelitis or abscess.
- Arteriography (MRA, CTA or catheter angiography).
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