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662 - Impact of parity on the angle of the first pedal ray relative to the midline of the foot

Friday, February 28, 2025

5:00 PM - 6:30 PM MST

Presenting Author(s)

PW

Paige Whitman, BS

Medical Student
Cooper Medical School of Rowan University
Westfield, New Jersey, United States

Co-Author(s)

CH

Christine Harper, PhD

Assistant Professor
Cooper Medical School of Rowan University
Camden, New Jersey, United States
PK

Patricia Kramer, PhD

Professor
University of Washington
Seattle, Washington, United States

Objectives: Pregnancy leads to structural and hormonal changes that impact foot morphology, including increased foot length and flattening of the pedal architecture, which can impact mobility and risk of injury. Previous research has demonstrated that females have a larger angle of the first pedal ray than males, which was suggested to be potentially related to parity. Here we compare variation in the first pedal ray angle between nulliparous and multiparous individuals to investigate the impact of pregnancy on this angle.

Design: Previously collected, de-identified non-weight-bearing CT scans from the New Mexico Decedent Image Database (n=16) of healthy individuals (8 nulliparous, 8 multiparous) were accessed. Landmarks were placed on the proximal and distal ends of the first metatarsal and third metatarsal in Avizo Lite 9.0.1. The vectors between these landmarks represented the first ray and midline of the foot, respectively, and the angle between the two axes was calculated in MATLAB. Wilcoxon Rank Sum tests were used to test for differences in the angle of the first ray between nulliparous and multiparous individuals.

Results: The angle of the first ray relative to the midline ranged from 6.9 to 10.6 degrees with an average of 9.5 degrees for multiparous, and 2.3 to 14.2 degrees with an average of 7.9 degrees for nulliparous. While this difference was not statistically significant (p=0.23), these pilot data suggest a difference between the two groups.

Conclusions: The impact of pregnancy on pedal architecture needs to be better characterized, and this research is a first step that identifies that the first pedal ray angle may differ between nulliparous and multiparous individuals. Our results are preliminary, however, and future research with a larger sample size should be conducted to fully understand if parity impacts first ray angle.