Progressive collapsing foot deformity (PCFD) is a debilitating condition causing significant biomechanical impairments. Custom-made foot orthoses (FOs) provide a non-invasive treatment by supporting the medial longitudinal arch and improving foot and ankle biomechanics. While previous studies on PCFD have predominantly investigated the biomechanical effects of FOs during walking, their impact on more demanding dynamic tasks remains unclear. This study aimed to investigate the effects of custom-made FOs on lower limb kinematics and kinetics during step-up (SU), step-down (SD), and step-down on a medially inclined surface (SDI) in individuals with PCFD. Twenty participants with flexible PCFD performed SU, SD and SDI tasks with and without FOs. Hip, knee, ankle and midfoot angles and moments were calculated and compared across conditions using one-dimensional statistical parametric mapping. Custom-made FOs reduced midfoot dorsiflexion across all tasks (SU: 4.9°; SD: 4.6°; SDI: 5.4°) and decreased ankle eversion during SU (2.9°) and SD (3.5°), but the reduction during SDI was non-significant. Custom FOs also reduced ankle inversion moments while increasing knee abduction moments during all step tasks. These findings indicate that custom-made FOs effectively support the medial longitudinal arch and limit foot pronation during dynamic movements, likely reducing loading on the medial ankle structures. However, their biomechanical efficacy was less pronounced when individuals with PCFD landed on a medially inclined surface. These findings highlight FOs potential as a conservative intervention for flexible PCFD to improve lower limb biomechanics.
Keywords: Ankle; Biomechanical phenomena; Foot; Lower extremity; Musculoskeletal diseases; Orthotic devices.
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