Muscle atrophy in diabetic patients with Charcot foot: a case-control study

PURPOSE: To evaluate the distribution and severity of muscle atrophy in diabetic patients with active Charcot foot (CF) compared to diabetic patients without CF. Furthermore, to correlate the muscle atrophy with severity of CF disease. MATERIAL/METHODS: In this retrospective study, MR images of 35 diabetic patients (21 male, median:62.1 years ± 9.9SD) with active CF were compared with an age- and gender-matched control group of diabetic patients without CF. Two readers evaluated fatty muscle infiltration (Goutallier-classification) in the mid- and hindfoot. Furthermore, muscle trophic (cross-sectional muscle area (CSA)), intramuscular edema (none/mild versus moderate/severe), and the severity of CF disease (Balgrist Score) were assessed. RESULTS: Interreader correlation for fatty infiltration was substantial to almost perfect (kappa-values:0.73–1.0). Frequency of fatty muscle infiltration was high in both groups (CF:97.1–100%; control:77.1–91.4%), but severe infiltration was significantly more frequent in CF patients (p-values: < 0.001–0.043). Muscle edema was also frequently seen in both groups, but significantly more often in the CF group (p-values: < 0.001–0.003). CSAs of hindfoot muscles were significantly smaller in the CF group. For the flexor digitorum brevis muscle, a cutoff value of 139 mm(2) (sensitivity:62.9%; specificity:82.9%) in the hindfoot was found to differentiate between CF disease and the control group. No correlation was seen between fatty muscle infiltration and the Balgrist Score. CONCLUSION: Muscle atrophy and muscle edema are significantly more severe in diabetic patients with CF disease. Muscle atrophy does not correlate with the severity of active CF disease. A CSA < 139 mm(2) of the flexor digitorum brevis muscle in the hindfoot may indicate CF disease. SUPPLEMENTARY INFORMATION: The online version contains supplementary material available at 10.1007/s00256-023-04328-1.