Walking with robot-generated haptic forces in a virtual environment: a new approach to analyze lower limb coordination

Abstract

Background Walking with a haptic tensile force applied to the hand in a virtual environment (VE) can induce adaptation effects in both chronic stroke and non-stroke individuals. These effects are reflected in spatiotemporal outcomes such as gait speed. However, the concurrent kinematic changes occurring in bilateral lower limb coordination have yet to be explored. Methods Chronic stroke participants were stratified based on overground gait speed into lower functioning (LF < 0.8 m/s, N = 7) and higher functioning (HF ≥ 0.8 m/s, N = 7) subgroups. These subgroups and an age-matched control group (N = 14, CG) walked on a self-paced treadmill in a VE with either robot-generated haptic leash forces delivered to the hand and then released or with an instrumented cane. Walking in both leash (10 and 15 N) and cane conditions were compared to pre-force baseline values to evaluate changes in lower limb coordination outcomes. Results All groups showed some kinematic changes in thigh, leg and foot segments when gait speed increased during force and post-force leash as well as cane walking. These changes were also reflected in intersegmental coordination and 3D phase diagrams, which illustrated increased intersegmental trajectory areas (p < 0.05) and angular velocity. These increases could also be observed when the paretic leg transitions from stance to swing phases while walking with the haptic leash. The Sobolev norm values accounted for both angular position and angular velocity, providing a single value for potentially quantifying bilateral (i.e. non-paretic vs paretic) coordination during walking. These values tended to increase (p < 0.05) proportionally for both limbs during force and post-force epochs as gait speed tended to increase. Conclusions Individuals with chronic stroke who increased their gait speed when walking with tensile haptic forces and immediately after force removal, also displayed moderate concurrent changes in lower limb intersegmental coordination patterns in terms of angular displacement and velocity. Similar results were also seen with cane walking. Although symmetry was less affected, these findings appear favourable to the functional recovery of gait. Both the use of 3D phase diagrams and assigning Sobolev norm values are potentially effective for detecting and quantifying these coordination changes.

Direct biomechanical manipulation of human gait stability: A systematic review

“…For walkers (U2), moderate and indicative evidence for reducing gait stability was found, respectively, for impaired subjects [ 83 , 84 ] and non-impaired subjects [ 85 , 86 ]. We found limited evidence for the improvement of gait stability with the use of walking-sticks and poles in impaired subjects (U1) [ 64 , 84 , 87 – 90 ]. In contrast, for non-impaired subjects indicative evidence for improving gait stability was found [ 64 , 91 , 92 ].…”

“…We found limited evidence for the improvement of gait stability with the use of walking-sticks and poles in impaired subjects (U1) [ 64 , 84 , 87 – 90 ]. In contrast, for non-impaired subjects indicative evidence for improving gait stability was found [ 64 , 91 , 92 ]. Other studies provided insufficient evidence.…”

Effect of exoskeleton robot-assisted training on gait function in chronic stroke survivors: a systematic review of randomised controlled trials

“…Exoskeleton robots are typically anchored to particular parts of the human body and simultaneously generate different forces or torques, allowing for interaction with the limb for enough degrees of freedom,17 while EE synchronises the patient’s feet with the correct walking pattern by simulating standing and swinging phases during gait training 18. Although several studies19–22 have discussed the efficacy of robotic-assisted training on gait improvement post-stroke, high-quality clinical data and convincing evidence are very limited.…”