Mild-to-Moderate Hallux Valgus Does Not Decrease Ankle Muscle Strength in Middle-Aged Japanese Women: A Comparative Study

Extreme hallux valgus has been documented to be related to lower functional ability and health-related quality of life. It also has a negative effect on foot structure and biomechanical characteristics, which in turn may affect muscle strength in the foot and ankle. Thus, the purposes of this study were to determine whether there is a difference of ankle muscle strength in varied hallux valgus deformities and to investigate correlations between hallux valgus angles and ankle muscle strength. Hallux valgus angles and ankle muscle strength data were collected from 31 middle-aged Japanese women. The hallux valgus angle was measured with a 3-dimensional foot scanner; ankle muscle strength was measured with a dynamometer. Results showed no differences in ankle muscle strength between normal and mild-to-moderate hallux valgus at both 60 degrees/second and 120 degrees/second (p > .05). Unexpectedly, women with mild-to-moderate hallux valgus had a greater value for inversion peak torque per body weight and eversion-to-inversion ratio than those with normal hallux valgus (p = .019 and p = .022) at 120 degrees/second. Furthermore, hallux valgus was correlated with inversion peak torque and peak torque per body weight (r = 0.47; p = .012 and r = 0.50; p = .007) and associated with eversion-to-inversion strength ratio (r = -0.47; p = .012). The findings indicated that mild-to-moderate hallux valgus did not result in a decrease in ankle muscle strength. Conversely, mild-to-moderate hallux valgus had greater ankle inversion strength in middle-aged Japanese women. Further studies are needed to investigate ankle muscle strength in severe hallux valgus deformities. (C) 2018 by the American College of Foot and Ankle Surgeons. All rights reserved.