Claude Pothrat1, Guillaume Authier2, Elke Viehweger3, Eric Berton4, Guillaume Rao5. 1. Aix-Marseille Université, CNRS, ISM UMR 7287, 13288 Marseille cedex 09, France. Electronic address: claude.pothrat@univ-amu.fr. 2. Aix-Marseille Université, CNRS, ISM UMR 7287, 13288 Marseille cedex 09, France; APHM, Hopital La Timone, Service d'orthopédie pédiatrique, 13005 Marseille, France. Electronic address: guillaume.authier@hotmail.fr. 3. Aix-Marseille Université, CNRS, ISM UMR 7287, 13288 Marseille cedex 09, France; APHM, Hopital La Timone, Service d'orthopédie pédiatrique, 13005 Marseille, France. Electronic address: elke.viehweger@ap-hm.fr. 4. Aix-Marseille Université, CNRS, ISM UMR 7287, 13288 Marseille cedex 09, France. Electronic address: eric.berton@univ-amu.fr. 5. Aix-Marseille Université, CNRS, ISM UMR 7287, 13288 Marseille cedex 09, France. Electronic address: guillaume.rao@univ-amu.fr.
Abstract
BACKGROUND: Biomechanical models representing the foot as a single rigid segment are commonly used in clinical or sport evaluations. However, neglecting internal foot movements could lead to significant inaccuracies on ankle joint kinematics. The present study proposed an assessment of 3D ankle kinematic outputs using two distinct biomechanical models and their application in the clinical flat foot case. METHODS: Results of the Plug in Gait (one segment foot model) and the Oxford Foot Model (multisegment foot model) were compared for normal children (9 participants) and flat feet children (9 participants). Repeated measures of Analysis of Variance have been performed to assess the Foot model and Group effects on ankle joint kinematics. FINDINGS: Significant differences were observed between the two models for each group all along the gait cycle. In particular for the flat feet group, opposite results between the Oxford Foot Model and the Plug in Gait were revealed at heelstrike, with the Plug in Gait showing a 4.7° ankle dorsal flexion and 2.7° varus where the Oxford Foot Model showed a 4.8° ankle plantar flexion and 1.6° valgus. INTERPRETATION: Ankle joint kinematics of the flat feet group was more affected by foot modeling than normal group. Foot modeling appeared to have a strong influence on resulting ankle kinematics. Moreover, our findings showed that this influence could vary depending on the population. Studies involving ankle joint kinematic assessment should take foot modeling with caution.
BACKGROUND: Biomechanical models representing the foot as a single rigid segment are commonly used in clinical or sport evaluations. However, neglecting internal foot movements could lead to significant inaccuracies on ankle joint kinematics. The present study proposed an assessment of 3D ankle kinematic outputs using two distinct biomechanical models and their application in the clinical flat foot case. METHODS: Results of the Plug in Gait (one segment foot model) and the Oxford Foot Model (multisegment foot model) were compared for normal children (9 participants) and flat feet children (9 participants). Repeated measures of Analysis of Variance have been performed to assess the Foot model and Group effects on ankle joint kinematics. FINDINGS: Significant differences were observed between the two models for each group all along the gait cycle. In particular for the flat feet group, opposite results between the Oxford Foot Model and the Plug in Gait were revealed at heelstrike, with the Plug in Gait showing a 4.7° ankle dorsal flexion and 2.7° varus where the Oxford Foot Model showed a 4.8° ankle plantar flexion and 1.6° valgus. INTERPRETATION: Ankle joint kinematics of the flat feet group was more affected by foot modeling than normal group. Foot modeling appeared to have a strong influence on resulting ankle kinematics. Moreover, our findings showed that this influence could vary depending on the population. Studies involving ankle joint kinematic assessment should take foot modeling with caution.