Charcot joint or neuropathic joint typically affects the ankle and tarsal joints due to diabetes. Tabes causes this phenomenon in the knees while syringomyelia leads to Charcot changes at the shoulder. This condition is characterized by the "six D's" of: (1) destruction, (2) density (increased), (3) disorganization, (4) dislocation, (5) distension (fluid), (6) debris. The typical appearance is that of severe hypertrophic changes and sclerosis due to ischemic necrosis.

A	AP and oblique radiographs of the foot. In addition to the acute fracture of the proximal phalanx of digit one, these two images show the typical appearance of Charcot changes at the tarsometatarsal joints.
B	Lateral radiograph of the foot. There is marked pes planus deformity along with sclerosis at the tarsometatarsal joints.

Links to online textbooks:

• Wheeless' Orthopedics: discussion of neuropathic joints

Links to online cases:

• Footdoc.com
• South Bank University

References:

• Simon SR, Tejwani SG, Wilson DL, Santner TJ, Denniston NL: Arthrodesis as an early alternative to nonoperative management of charcot arthropathy of the diabetic foot J Bone Joint Surg Am. 2000 Jul;82-A(7):939-50.           [See related articles]
• Tomas MB, Patel M, Marwin SE, Palestro CJ: The diabetic foot Br J Radiol. 2000 Apr;73(868):443-50.           [See related articles]