Hallux valgus (HV) has been linked to functional disability and increased risk of falls, but mechanisms underpinning functional disability are unclear. This study investigated functional performance, muscle strength, and plantar pressures in adults with mild, moderate, and severe HV compared to controls, while considering the influence of foot pain.
Sixty adults with HV (classified as mild, moderate, and severe on dorsalplantar radiographs) and 30 controls participated. Measures included hallux plantar flexion and abduction strength, walking performance, postural sway, and forefoot plantar pressures. Multivariate analysis of covariance and pairwise comparisons (P < 0.05 after Bonferroni adjustment) were used to investigate differences between groups, adjusting for age, sex, body mass index, and foot pain.
Hallux plantar flexion and abduction strength were significantly reduced in those with moderate (mean differences: plantar flexion -45.8 N, abduction -12.3 N; P < 0.001) and severe HV (plantar flexion -50.1 N; P < 0.001, abduction -11.2 N; P = 0.01) compared to controls. A significant reduction in hallux peak pressure and pressure-time integral was evident in moderate (peak pressure -90.8 kPa; P < 0.001) and severe HV (peak pressure -106.2 kPa; P < 0.001) compared to controls. Those with severe HV also demonstrated increased mediolateral postural sway in single leg stance compared to controls (3.5 cm; P = 0.01).
Moderate to severe HV is associated with reduced hallux plantar pressures and strength measures, while relatively normal function compared to controls was found in those with mild deformity. Greater understanding of specific functional deficits associated with different stages of HV will help inform clinical management and future research.