Weightbearing CT assessment of foot and ankle joints in Pes Planovalgus using distance mapping.

Abstract Introduction The goal of this study was to describe the abnormal joint surface interaction at the ankle, hindfoot and midfoot joints in patients presenting with Pes Planovalgus (PPV) using three-dimensional (3D) distance mapping on weightbearing computed tomography (WBCT) images by comparing a series of PPVs to a series of normally-aligned feet. We hypothesized that in PPVs joint interactions would reveal significantly increased spaces in the medial side of the ankle, hindfoot and midfoot joints. Methods In this case-control study, ten feet (10 patients) with asymptomatic PPV were compared to 10 matched-paired (by age, gender and body mass index) normally-aligned feet (10 patients). Three-dimensional models were produced from the images and distance maps representing joint surface configuration were generated for the ankle, hindfoot and midfoot joints. The distance maps for each joint were then compared between the two groups and between regions in the same group. Results In PPV patients there was a significantly increased surface-to-surface distance anteromedially at the ankle joint (+46.3%, p  Conclusion We found significant differences in surface-to-surface interaction at the foot and ankle joints between Pes Planovalgus and normally-aligned controls. Distance mapping on WBCT images could be used in clinical practice as a diagnostic support to gauge the morphological changes of articular spaces occurring in Pes Planovalgus. Level of evidence Level III, case-control study.