Charcot neuropathic osteoarthropathy (CN), commonly referred to as the Charcot foot, is a condition affecting the bones, joints, and soft tissues of the foot and ankle, characterised by inflammation in the earliest phase. It is a complication of peripheral neuropathy, and can therefore be seen in patients with other causes of peripheral neuropathy. The condition is thought to be related to uncontrolled release of proinflammatory cytokines (especially IL-1p and TNF-a) following minor trauma, infection or surgery. Continued mobilisation on an insensate foot leads to on-going bone destruction, subluxation, dislocation, and eventual deformity.
Diagnosis is clinical in the first instance and the clinician should be alert to any patient with neuropathy presenting with a unilateral inflamed foot. As the foot is insensate patients may not remember a history of trauma and therefore
Figure 5.5 Acute Charcot neuropathic osteoarthropathy may be misdiagnosed as cellulitis, venous thrombosis or gout
The condition is frequently misdiagnosed as cellulitis, gout or venous thrombosis (Fig. 5.5). If the patient is allowed to continue to mobilise whilst investigations for these are being pursued further bony damage may occur.
X-rays may be normal in the first instance, or show subtle fractures and dislocations or later show more overt fractures and subluxations. If the X-ray is normal an MRI scan should be performed although the changes can be difficult to distinguish from osteomyelitis and, indeed, the two can co-exist.