A 60-year-old diabetic man with a painless, grossly deformed ankle undergoes radiography. Findings include joint disorganisation, fragmentation of the talar dome, dense subchondral sclerosis, and large irregular osteophytes, with disproportionate preservation of mineralisation. The most likely diagnosis is:

• A Severe primary osteoarthritis
• B Neuropathic (Charcot) arthropathy ✓
• C Charcot-Marie-Tooth disease
• D Calcium pyrophosphate deposition disease

Explanation

The combination of the five Ds, namely disorganisation, destruction, debris, density increase (subchondral sclerosis), and dislocation, with intact bone mineralisation, defines neuropathic arthropathy, classically seen in diabetic feet. Severe osteoarthritis lacks fragmentation and debris, and CPPD shows chondrocalcinosis with a different distribution. The key discriminator against osteoarthritis is the degree of disorganisation out of proportion to symptoms.

Reference: Robbins and Cotran Pathologic Basis of Disease, 10th ed.

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Written and medically reviewed by the StethoPrep medical team.