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Diabetic foot and Charcot neuroarthropathy
In a diabetic patient with neuropathy, a warm, swollen, red foot with little pain is an active Charcot foot until proven otherwise; the urgent treatment is complete offloading in a total contact cast to prevent collapse of the arch and permanent deformity.
Why it matters in the exam
The typical stem describes a patient with long-standing diabetes and neuropathy who presents with a swollen, warm foot, sometimes after minor unnoticed trauma. The main differential is cellulitis, osteomyelitis and venous thrombosis. Clues for Charcot: a temperature difference of more than 2 degrees between the two feet, no open wound, redness that fades when the leg is raised and little pain for the findings. Radiographs may be normal early, and MRI shows bone marrow oedema and microfractures. In contrast, a deep ulcer in which a probe touches bone (probe-to-bone) strongly suggests osteomyelitis. The disease progresses through the Eichenholtz stages: an active stage of fragmentation, a stage of coalescence and a stage of reconstruction. The usual site is the midfoot, and a rocker-bottom deformity creates a pressure point and an ulcer on the sole. Treatment in the active stage is a total contact cast without weight-bearing or with limited weight-bearing until swelling and warmth settle and the temperature difference is below 2 degrees, followed by a protective boot and custom footwear. Surgery is kept for an unstable deformity, recurrent ulcers or failure of conservative care. In a diabetic foot with an ulcer, assessment also includes blood supply, because ischaemia changes treatment and prognosis.
Key points
- A warm swollen foot with little pain in a diabetic patient — Charcot until proven otherwise.
- A temperature difference of more than 2 degrees between the feet.
- MRI diagnoses early; radiographs may be normal.
- Treatment: total contact cast and offloading.
- Permanent deformity — rocker-bottom foot and ulcers.
Summary table
| Condition | Distinguishing finding | Test | Treatment |
|---|---|---|---|
| Active Charcot | Warm swollen foot, temperature difference above 2 degrees, no wound | Radiograph and MRI | Total contact cast and offloading |
| Cellulitis | Redness that does not fade on elevation, sometimes an entry point | Clinical examination and blood tests | Antibiotics |
| Osteomyelitis | Deep ulcer, probe touches bone | MRI and bone biopsy | Debridement and prolonged antibiotics |
| Chronic Charcot with deformity | Rocker-bottom foot and plantar ulcer | Weight-bearing radiograph | Custom footwear; surgery for unstable deformity |
| Ischaemic foot | Weak pulses, cold skin | Ankle-brachial index and Doppler | Referral to vascular surgery |
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Sources
- IWGDF Guidelines on the Prevention and Management of Diabetes-related Foot Disease, 2023 — Charcot Neuro-osteoarthropathy; Infection
- Campbell's Operative Orthopaedics, 14th ed. (2021) — Diabetic Foot
Sources are given for further reading; the text is written afresh and not copied from them.
Reviewed by the Examqo AI Professor · 2026-11-06. The text may contain errors; when in doubt, check the source.