Dynamic Biomechanical Consequences of Hallux Valgus: A Multimodal Investigation of Lower Limb Compensation Patterns

Hallux valgus (HV), characterized by triplanar deviation of the first metatarsophalangeal joint, significantly alters foot biomechanics and provokes adaptations along the kinetic chain. While its static effects are well-documented, its dynamic impact during high-velocity, multiplanar maneuvers remains unclear. This study investigated the dose-dependent relationship between HV severity and lower limb stability during side-cutting using a novel multimodal validation framework. Sixty-six male participants (n = 22 per group: normal, mild, and moderate HV) underwent biomechanical evaluation through three-dimensional motion capture, inverse dynamics-driven finite element (FE) modeling, and dynamic fluoroscopy. Real-time bone displacement was quantified using shape-matching algorithms to validate FE simulations. Results indicated compensatory adaptations in HV groups, such as reduced first metatarsal dorsiflexion and external rotation of the first metatarsophalangeal joint. Dynamic fluoroscopic data revealed progressive displacement in the tibiotalar and subtalar joints, with significantly increased posterior glide (p < 0.001). Kinematic correlations showed a decline in ankle plantarflexion (p < 0.001) and hip flexion (p < 0.001) with advancing HV severity, while moderate HV was associated with significantly greater knee valgus angles (R² = 0.47, p < 0.001). FE simulations demonstrated a non-linear increase in contact pressures at the first MTPJ and lateral metatarsal overload. These findings reveal that HV induces a compensatory kinematic cascade through load redistribution and altered joint dynamics, destabilizing three-dimensional lower limb alignment. By linking pathological tissue loads to vector field shifts, this multiscale framework enhances our understanding of injury mechanisms and offers insights into kinematic chain optimization for injury prevention.