A New Natural History of Charcot Foot

Abstract

The purpose of this study is to describe the usefulness of 18F-FDG PET/CT scanning in the diagnosis and follow-up of stage 0 Charcot foot (CNO) and CNO outcomes when therapeutic options are driven by this image modality. We selected 25 out of 40 diabetic patients with an acute CNO, without any bone involvement at x-ray (stage 0 CNO). Diagnostic criteria were inflammatory clinical signs of the affected foot and skin temperature difference greater than 2°C compared with the contralateral foot (ΔT). All patients underwent x-ray, MRI, and 18F-FDG PET/CT scanning (expressed as standardized uptake value, SUVmax) at baseline (T0). All patients underwent another 18F-FDG PET/CT within 1 month after ΔT was less than 2°C [clinical recovery (T1)] and again every 3 months until SUVmax was less than 2 [final recovery (T2)]; at this time, MRI confirmed the end of the inflammatory condition. T0 ΔT was 3.04 ± 1.65°C. All patients showed T0 SUVmax of the affected foot higher than the contralateral one (3.83 ± 1.087 vs. 1.24 ± 0.3; P < 0.001). At clinical recovery (T1), defined by ΔT below 2°C, the inflammatory signs were no longer present (T0 vs. T1 ΔT = 3.04 ± 1.65 vs. 0.9 ± 0.55°C; P < 0.0001). At T1, SUVmax was unchanged from T0 (3.80 ± 1.69 vs. 3.83 ± 1.09; P = ns). At final recovery (T2), ΔT was 0.74 ± 0.29°C (similar to T1 ΔT), while the SUVmax dropped from T1 to T2 (3.8 ± 1.69 vs. 1.72 ± 0.52; P < 0.0001). Standard therapy was total contact cast and removable cast walker until T2 (15.12 ± 5.45 mo). No patient developed foot bone fractures nor had relapses during follow-up (21.75 ± 16.7 mo). PET/CT scan allows the quantification of the inflammatory process; therefore, it may drive clinical decisions in the management of acute CNO better than clinical criteria. None of our patients developed foot bone fractures or had relapses during follow-up driven by PET/CT scan.