How does wearing a lumbar orthosis interfere with gait initiation?

The interaction between medical devices and the human body must be evaluated in standardised laboratory tests. Since wearing a lumbar orthosis is assumed to reduce lower back mobility and reinforce trunk movement control through imposed lordosis, this device is expected to affect gait initiation which requires trunk and pelvic rotations. Thirteen healthy subjects were asked to initiate gait without orthosis (control) and orthosis with or without lordosis constraints. The biomechanical parameters usually reported for gait initiation were studied and no statistically significant effects were found. Indeed, the duration of the anticipation, and execution phases and maximal instantaneous velocity of centre of gravity at the end of the first step were not modified by the experimental conditions. The lack of interference underlines the robustness of the gait initiation parameters, which therefore may lead subjects to adopt adaptive strategies to retain this invariance. Future experiments should be conducted to highlight these strategies. Practitioner Summary: The aim of this study was to investigate the effect of various lumbar orthosis characteristics on gait initiation organisation. The results, based on a dynamic analysis of balance strategies, showed that the medical device had no repercussions on movement control. Several explanations are proposed, which should be validated by future studies.