Quantifying clinical misinterpretations associated to one-segment kinetic foot modelling in both a healthy and patient population.

BACKGROUND

Rigid foot modelling approaches are still widely used to assess ankle joint kinetics in clinical biomechanical research. Yet, studies on healthy subjects using multi-segment kinetic foot models indicated that one-segment kinetic foot models tend to overestimate ankle joint kinetic data. Our aim was to compare ankle joint kinetics computed with a one-segment versus a multi-segment kinetic foot model in both asymptomatic and pathological gait. We also assessed whether differences between models can lead to different interpretations in clinical decision-making.

METHODS

A two-factor repeated measure analysis of variance was performed to investigate differences in ankle joint kinetics, with the first factor being group effect (control vs. patients) and second factor being foot model effect (one-segment vs. multi-segment). Minimal detectable change was calculated to assess the clinical relevance of the observed differences in ankle joint kinetics.

FINDINGS

Ankle joint peak kinematic, angular velocity and kinetic variables were all significantly overestimated (P < 0.05) when computed with the one-segment kinetic foot model. Kinetic differences in peak plantarflexion angular velocity and peak power generation were higher than their MDC-values.

INTERPRETATION

Ankle joint kinetics are significantly overestimated when computed with a rigid foot modelling approach in both asymptomatic and pathological gait. This overestimation leads to clinical misinterpretations as MDC-values were less than the observed overestimation. In future studies, it is of clinical relevance to assess ankle joint kinetics with a multi-segment foot modelling approach.