Exploring the relationship between the supination resistance test and the effects of foot orthoses on the foot and ankle biomechanics during walking

Background: The effects of foot orthoses on lower limb biomechanics during walking have been studied extensively. However, the lack of knowledge regarding the effects of various foot orthoses models for the same population complicates model selection in clinical practice and research. Additionally, there is a critical need to enhance our ability to predict the outcomes of foot orthoses using clinical tests, such as the supination resistance test.

Research question: What are the effects of two commonly prescribed types of FO (thin-flexible and medially wedged) on lower limb biomechanics during gait? Is there a correlation on these effects with the results of the supination resistance test?

Methods: Twenty-three participants with flat feet were enrolled in this cross-sectional descriptive study. Participants underwent walking trials under three conditions: shod, thin-flexible FOs and medially wedged FOs. Midfoot, ankle, knee and hip angles, moments were calculated. Repeated measure ANOVAs were employed for within-group comparison across conditions. Correlations between the effects of FOs on foot and ankle angles/moments and supination resistance were determined using regression analyses using a statistical parametric mapping approach.

Results: Thin-flexible and medially wedged FOs reduced midfoot dorsiflexion angles and ankle inversion moments. Medially wedged FOs also decreased midfoot and ankle abduction angles, midfoot plantarflexion moments compared to thin-flexible FOs and shoes. Moderate to good correlations between the supination resistance test and the medially wedged FOs were observed for the frontal and transverse ankle angles and moments.

Significance: Medially wedged FOs are more effective in modifying lower limb biomechanics during walking compared to thin-flexible FOs. Greater supination resistance was associated with more pronounced effects for medially wedged FOs on foot and ankle biomechanics. These findings hold promise for refining orthotic prescription strategies, potentially offering advantages to individuals with musculoskeletal disorders.