Nonunion After First Metatarsophalangeal Joint Arthrodesis: The Association With Shoe Size

Introduction: First metatarsophalangeal joint (MTPJ) arthrodesis is a common treatment for various foot conditions, with nonunion as a frequent complication. The incidence of nonunion varies widely in the literature. In particular, males have a higher risk of nonunion than females. This is possibly due to biomechanical and anatomical differences, as men have on average larger feet than women. This study therefore aims to explore whether shoe size, as a proxy for foot size, affects nonunion rates and could explain the gender disparity in nonunion rates. Methodology: An exploratory analysis of retrospectively collected data from patients who underwent primary first MTPJ arthrodesis in a single secondary hospital between January 2012 and December 2019. Additional data on body weight, height, and shoe size were prospectively collected from patients. Results: Among 261 included patients, 57 (21.8%) experienced nonunion. Nonunion incidence was higher in males (18, 26.9%) than in females (39, 20.1%). Self-reported shoe size showed no significant association with nonunion in both univariate and multivariate analyses. Discussion: The study's findings suggest that shoe size, as a proxy for foot size, is not associated with nonunion after the first MTPJ arthrodesis. Despite observing a gender difference in nonunion rates, this disparity could not be explained by shoe size. Conclusions: Shoe size as a proxy for foot size appears to have no clinical association with nonunion following the first MTPJ arthrodesis.