Summary

Charcot Neuroarthropathy (CN), commonly known as Charcot Foot, is a progressive, destructive condition of the bones and joints in a foot with peripheral neuropathy. It most commonly occurs in patients with diabetic peripheral neuropathy. The combination of loss of protective sensation and ongoing weight-bearing leads to microfractures, joint dislocations, and bony collapse. The acute phase presents with a hot, red, swollen foot – often painless or only mildly painful due to neuropathy – which mimics infection (cellulitis, osteomyelitis). The key differentiator is that acute Charcot improves with elevation, while infection does not. If untreated, the midfoot collapses into a "Rocker Bottom" deformity, causing plantar ulceration and high amputation risk. Management involves immediate offloading (Total Contact Cast), immobilisation until the acute phase resolves (Eichenholtz stages), and protective footwear long-term.

Key Facts

• Cause: Peripheral Neuropathy (Diabetes – Most Common).
• Mechanism: Loss of protective sensation + Uncontrolled weight-bearing -> Microfractures -> Bony collapse.
• Acute Presentation: Hot, Red, Swollen, (Painless) Foot. MIMICS INFECTION.
• Key Differentiator: Elevation reduces redness/warmth in Charcot (Not in Infection).
• Chronic/End-Stage: Rocker Bottom Deformity (Midfoot Collapse).
• Treatment (Acute): Total Contact Cast (TCC). Non-Weight Bearing. ("Cool the Foot").
• Treatment (Chronic): CROW Walker/Boot. Custom Footwear. Surgery for Deformity.

Clinical Pearls

"Hot Foot in a Diabetic – Think Charcot, Not Just Infection": Acute Charcot and Cellulitis/Osteomyelitis present identically. Differentiate with the Elevation Test (Charcot redness improves, Infection does not).

"Painless Destruction": Due to neuropathy, patients may walk on a broken, dislocating foot without significant pain. Early recognition is crucial.

"Rocker Bottom = High Amputation Risk": Once the midfoot collapses, abnormal pressure points cause ulcers, which lead to infection and amputation.

"Off-Load, Off-Load, Off-Load": The cornerstone of Charcot management is complete offloading. Continued weight-bearing destroys the foot.

Why This Matters Clinically

Charcot Foot is frequently misdiagnosed as infection, leading to unnecessary antibiotics and delayed treatment. Early recognition and aggressive offloading can prevent catastrophic deformity and amputation.

Inspection

• Erythema, Swelling in acute phase.
• Deformity (Rocker Bottom, Midfoot sag) in chronic phase.
• Ulceration? Infection signs?

Palpation

• Temperature (Use thermometer. Compare sides. >2°C difference significant).
• Bony prominences.
• Peripheral pulses (Often bounding in acute Charcot).

Neurological Assessment

• Peripheral Neuropathy Assessment: 10g Monofilament, Vibration sense.
• Document sensory loss.

Vascular Assessment

• Pulses, ABPI if indicated.

• With Early Offloading: Deformity can be minimised. Ulcer/Amputation risk reduced.
• Without Offloading: Collapse, Rocker Bottom, Ulceration, Infection, Amputation.
• Amputation Rate: Significantly elevated in Charcot patients, especially with ulcers.

Key Guidelines

Scenario 1:

• Stem: A 55-year-old diabetic with peripheral neuropathy presents with a hot, red, swollen left foot. He has no pain. Pulses are bounding. X-ray is normal. How do you differentiate from cellulitis?
• Answer: Elevation Test: Elevate the foot. If redness/warmth improves after 15 minutes, suspect Charcot. If it persists, suspect infection. Also check inflammatory markers (CRP, WCC) – often normal in Charcot.

Scenario 2:

• Stem: What is the acute management of Charcot Foot?
• Answer: Immediate Offloading with Total Contact Cast (TCC) or Removable Cast Walker. Non-weight bearing. Continue until the foot "cools" (Temperature difference <2°C compared to other foot).

Scenario 3:

• Stem: What is the "Rocker Bottom" deformity?
• Answer: Midfoot collapse (typically Chopart/midtarsal region) leading to a convex plantar surface with bony prominence. This creates abnormal pressure points, leading to ulceration.

What is Charcot Foot?

Charcot Foot is a condition where the bones in your foot break down and collapse because you cannot feel pain properly (due to nerve damage from diabetes). Because you don't feel pain, you keep walking on a broken foot, making it worse.

What are the symptoms?

• Hot, red, swollen foot.
• The foot may not be painful (or only mildly aching).
• If left untreated, the foot can collapse and become deformed ("Rocker Bottom").

How is it treated?

• Offloading: Wearing a special cast or boot so you don't put weight on the foot.
• Protective footwear: Special shoes to prevent pressure ulcers.
• Surgery: Sometimes needed if the foot collapses badly.

Key Counselling Points

1. Don't Walk On It: "Walking on your foot will make it collapse. You must use the cast or boot."
2. Check Your Feet Daily: "Neuropathy means you can't feel injuries. Look at your feet every day."
3. Long-Term Footwear: "You will need special shoes for life to protect your feet."
4. Diabetic Control: "Good blood sugar control helps prevent further problems."

• Jean-Martin Charcot (1868): French neurologist who described neuropathic arthropathy in patients with Tabes Dorsalis (Syphilis).
• Diabetes Now Predominates: With the decline of syphilis and increase in diabetes, diabetic neuropathy is now the leading cause globally.