Evaluation of the diabetic charcot foot by MR imaging or plain radiography--an observational study.

Magnetic resonance (MR) images and concomitant plain radiographs of 26 Charcot feet of different stages (stage 0 to III) were reviewed in retrospect for discordant findings. Bone and joint abnormalities were evaluated qualitatively, and quantitatively guided by the AO integral classification of injuries of the foot. MR images revealed traumatic bone and joint injuries (bone oedema, occult fractures, and joint effusion) already in stage 0, when X-ray still showed normal bone and joint anatomy (p = 0.02). Moreover, MR images revealed bone oedema, joint effusion and soft tissue oedema in addition to fractures and calluses in stage I (bone dissolution), stage II (bone coalescence), and stage III (bone remodeling), i.e., in stages with overt radiographic pathology. According to this observational study, MR imaging, in addition to radiography, provides important information as to the extent and the natural course of bone injury in the diabetic Charcot foot. MR imaging, thus, may improve disease staging, as well as treatment monitoring.