IS Case 327: Charcot foot
Imaging Sciences URMC 2009
Publication Date: 2009-09-15
Patient is a 49-year-old male with suspicion of osteomyelitis.
Initial images from 18 months ago demonstrate partial amputation of the fifth digit at the level of the mid-shaft of the fifth metatarsal. There is fragmentation at the stump of the fifth metatarsal. There is soft tissue lucency that would suggest the presence of an ulcer in the region of the base of the fifth metatarsal. Findings suggest the presence of osteomyelitis.
Current follow-up images demonstrate disorganization at the talonavicular and navicular cuneiform joints. There is vertical orientation of the talus and there is a dislocation of the navicular cuneiform joints. Fragmentation of the bony structures is present. Findings are consistent with Charcot arthropathy.
Charcot joint is essentially the same as a neuropathic joint. Both terms describe the abnormalities of bones and joints as a result of neurologic deficits. Diabetic neuropathy is the most common cause, occurring in up to 10-15% of diabetics. Other causes include; alcoholism, tabes dorsalis, congenital pain insensitivity, and meningomyelocele. These conditions all result in chronically instable joints, abnormal joint loading, altered proprioception, and reduced pain sensation. This results in a destructive cycle of repetitive injury. Charcot joints have a typical rapidly progressive and destructive course. Charcot joints are characterized by destruction, dislocation, disorganization, distention, debris, and increased density.
Plain radiographs are all that are usually needed to make to diagnosis of a Charcot joint. Radiographic findings include associated joint effusions, osseous bony debris, cartilage and bone destruction, joint laxity with subsequent dislocation, and finally joint disorganization. CT demonstrates similar findings and is usually not needed in the diagnosis of Charcot joint. MRI is a secondary exam in the diagnosis of Charcot joint. MRI is typically used for solving a specific problem, such as differentiating a Charcot joint from osteomyelitis.
Differential diagnosis of Charcot joint includes osteomyelitis, septic joint, osteoarthritis, inflammatory arthritis, chrondrosarcoma (shoulder), diskitis (spine).
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