Two-dimensional vs three-dimensional analysis of weightbearing Charcot neuropathy deformities

Clinical standards for diagnosing Charcot neuroarthropathy (CN) rely on two-dimensional (2D) radiographs, despite the complex three-dimensional (3D) deformities. This study utilized a 3D measurement method, previously applied to nonweightbearing imaging, for weightbearing imaging to quantify deformities in CN patients and compared these to 2D weightbearing radiographs (WBR).

This retrospective study included seven CN patients who underwent both 2D WBR and 3D weightbearing CT scans (WBCT). Five observers manually annotated 2D radiographs, and placed 3D fiducial markers on anatomic landmarks that were processed using a patient-specific coordinate system. Paired t-tests and Bonferroni adjustment (p_adj) compared 2D and 3D values.

The 3D WBCT measurements revealed significantly greater anteroposterior talocalcaneal angles (153.59 degrees ± 2.49 vs. 19.98 degrees ± 1.74, p < 0.0001, p_adj< 0.0001) and talonavicular angles (10.61 degrees ± 2.16 vs. 1.75 degrees ± 0.25, p < 0.0001, p_adj<0.0001). Unadjusted medial and lateral column heights were significantly higher on WBCT (25.31 mm ± 3.70 vs. 14.09 mm ± 2.39, p = 0.001, p_adj=0.009; 15.60 mm ± 2.39 vs. 8.17 mm ± 2.29, p = 0.027, p_adj=0.243, respectively). Tibiotalar angles were significantly lower on WBCT (91.72 degrees ± 1.27 vs. 124.05 degrees ± 2.04, p < 0.0001, p_adj< 0.0001).

Comparisons between the novel method of analyzing 3D WBCT and standard analysis of 2D WBR revealed significant differences in several angular and distance measurements of pathological deformities in CN. Measurements related to forefoot abduction, midfoot arch height, and hindfoot valgus alignment differ from 2D WBR compared to 3D WBCT.