# An Exploratory Statistical Shape Modeling Analysis of Three‐Dimensional Foot Alignment in Female Patients With Progressive Collapsing Foot Deformity

## TL;DR

This study uses 3D modeling to analyze foot deformities in women with PCFD, revealing unique joint alignment patterns compared to healthy controls.

## Contribution

A new multi-domain statistical shape model from SW-CT data is applied to study 3D foot alignment in PCFD.

## Key findings

- The Chopart and subtalar joints are inverted, while the Lisfranc joint is everted in PCFD patients.
- The talonavicular joint spreads medially in a fan-like direction in PCFD.
- Subtalar and Chopart joints show coordinated changes, while the Lisfranc joint varies oppositely.

## Abstract

Progressive collapsing foot deformity (PCFD) is a complex condition characterized by multiple combined deformities, with a higher reported prevalence in women. Most studies of PCFD morphology have focused on single joints and evaluated both sexes together, leaving the interrelationship of multiple joints in females specifically unassessed. In this study, we developed a multi‐domain statistical shape model (SSM) from reconstructions of simulated weight‐bearing computed tomography (SW‐CT) image data to investigate variations in 3D foot alignment in women by comparing the morphology of patients with PCFD to that of their asymptomatic control counterparts.

We developed an SSM to analyze the 3D alignment in the foot, including the distal tibia, distal fibula, talus, calcaneus, navicular, cuboid, and each of the cuneiforms and metatarsal bones. Model results were compared between 23 female patients with PCFD and 23 female asymptomatic individuals.

Although the Chopart, subtalar, and Lisfranc joints were dorsiflexed and abducted, the Chopart and subtalar joints were inverted whereas the Lisfranc joint was everted, indicating that deformity of the Lisfranc joint occurred in the opposite direction to that of the subtalar and Chopart joints.

The application of a multi‐domain SSM from SW‐CT to evaluate alignment deformities in patients with PCFD represents a new and novel approach to understanding the pathophysiology of this condition. In PCFD, the subtalar and Chopart joints showed coordinated changes, whereas the Lisfranc joint demonstrated variation in the opposite direction. Also, the talonavicular joint spreads out medially in a fan‐like direction in PCFD.