This location is highly suggestive of a diabetic etiology; other location are characteristic :
The best imaging clues are included in this mnemonic : 6 Ds 1
- dense bones (subchondral sclerosis)
- degeneration
- destruction of articular cartilage
- deformity (pencil-point deformity of metatarsal heads)
- debris (loose bodies)
- dislocation
The main differential diagnosis is osteomyelitis and, in some cases, it can evolve as fast.