The Influence of Bilateral and Unilateral Flatfoot on Coronal Spinopelvic Alignment in Asymptomatic Young Healthy Males

Background: This cross-sectional retrospective study aimed to present the influence of unilateral and bilateral flatfoot on coronal spinopelvic alignment in asymptomatic young healthy males. Methods: This study was performed by examining the medical reports of individuals who applied to the National Health Board to work in positions requiring physical fitness between January 1, 2018, and January 1, 2019. Plain radiographs of the feet, pelvis, and spine were analyzed. The calcaneal pitch angle for flatfoot, pelvic obliquity, and the Cobb angle for spinal asymmetry were measured. After all of the analyses were completed, participants were divided into two groups—unilateral or bilateral flatfoot, depending on the calcaneal pitch angle measurements—and compared. Results: There was no significant difference in age between groups ( P = .609). The unilateral flatfoot group showed higher values in terms of body mass index, with a significant difference ( P = .01). The curve patterns were identified as single thoracic, lumbar, and double. Post-hoc analyses suggest that young males without spinal asymmetry were more likely to have unilateral flatfoot ( P < .008). There were significant differences between groups in pelvic obliquity and Cobb angle ( P < .05). The effect size was found to be small to medium for pelvic obliquity and medium to large for Cobb angle. Conclusions: Young males with bilaterally increased foot pronation demonstrate more increased pelvic obliquity and spinal curvature.