Characteristics of hindfoot morphology and ankle range of motion in young women with hallux valgus

BACKGROUND: Hallux valgus occurs more frequently in women as they age; therefore, it is beneficial to prevent hallux valgus in younger women. The purpose of this study was to clarify the characteristics of hindfoot morphology and the range of motion of the ankle joint with hallux valgus in young women. METHODS: The participants were 140 young women (mean age 18.8 ± 0.6 years). A three-dimensional footprint automatic measurement apparatus was used to measure the hallux valgus angle in the standing position and the arch-height ratio and heel-floor angle (HFA) in the standing and chair-sitting positions. The amount of change in foot morphology owing to differences in posture was calculated. The range of motion of the ankle joint dorsiflexion, plantarflexion, inversion, and eversion was measured. Participants were classified into two groups according to the presence of hallux valgus. Statistical analysis was used to compare hindfoot morphology and range of motion between the two groups, and the correlation between foot morphology and range of motion was investigated depending on the presence of hallux valgus. RESULTS: With hallux valgus, the HFA tilted inwards (p = 0.010), and the change in the arch-height ratio due to the difference in posture was large (p = 0.021). There was no difference in the range of motion of the ankle joints with or without hallux valgus. In women with hallux valgus, the amount of change in arch height and HFA was correlated with the range of motion of eversion (r = 0.391, p = 0.027; r = -0.362, p = 0.042). CONCLUSIONS: With hallux valgus, the hindfoot pronated, and the arch height decreased from sitting to standing. Furthermore, the amount of change in the hindfoot and midfoot due to posture was related to the range of motion of eversion.