Introduction: Gait rehabilitation with partial body weight unloading (BWU) is a common method of rehabilitation for patients with neurological and musculoskeletal impairments. However, the efficiency of this method is hard to assess as long as the walking modality (treadmill vs. overground) and subjects& overground gait speed variability, when suspended to the unloading system, confound the effects of BWU. By designing a mechanical device that pulled the Biodex unweighing system (Figure 1) and enabled healthy subjects (N=10) to maintain a comfortable overground speed, this study could assess the unique effects of BWU on gait biomechanical parameters under conditions that replicate daily walking. Methods: Subjects walked overground under a control (no suspension vest) and three (0%,15%,30%) BWU experimental conditions. Hip, knee and ankle spatiotemporal, kinematics, and kinetics measures were recorded for all conditions (six trials per condition). Results: Pairwise comparison of control and 0% conditions indicated pronounced modifications in hip and knee kinematics resulting from accommodation to being suspended by a vest prior to any weight reduction. Once accommodation occurred, pairwise comparisons of gait parameters under 0%, 15%, 30% BWU conditions showed that despite the inverse relationship observed between increased body weight reduction and decreased hip flexion and knee and ankle extension moments, the ankle range of motion and plantarflexion remained unchanged and joints kinematic trajectories were highly similar under all conditions (Figure 2).
Figure 2. Mean angular trajectories
Conclusion: Gait rehabilitation conducted overground with up to 30% BWU may safely reduce joints load without modifying gait patterns or the ankle plantarflexion needed for forward propulsion.
