Evolving Toward Subject-Specific Gait Rehabilitation Through Single-Joint Resistive Force Interventions

Abstract

Walking is one of the most relevant tasks that a person performs in their daily routine. Despite its mechanical complexities, any change in the external conditions that applies some external perturbation, or in the human musculoskeletal system that limits an individual's movement, entails a motor response that can either be compensatory or adaptive in nature. Incidentally, with aging or due to the occurrence of a neuro-musculoskeletal disorder, a combination of such changes including reduced sensory perception, muscle weakness, spasticity, etc. has been reported, and this can significantly degrade the human walking performance. Various studies in gait rehabilitation literature have identified a need for the development of better rehabilitation paradigms and have implied that an efficient human robot interaction is critical. Understanding how humans respond to a particular gait alteration can be beneficial in designing an effective rehabilitation paradigm. In this context, the current work investigates human locomotor adaptation to resistive alteration to the hip and ankle strategies of walking. A cable-driven robotic system, which does not add mobility constraints, was used to implement resistive force interventions within the hip and ankle joints separately through two experiments with eight healthy adult participants in each. In both cases, the intervention was applied during the push-off phase of walking, i.e., from pre-swing to terminal swing. The results showed that subjects in both groups adopted a compensatory response to the applied intervention and demonstrated intralimb and interlimb adaptation. Overall, the participants demonstrated a deviant gait implying lower limb musculoskeletal adjustments as if to compensate for a hip or ankle abnormality.

Mapping-Based Dosage of Gait Modification Selection for Multi-Parameter, Subject-Specific Gait Retraining

“…Reducing knee loading as an alternative for knee osteoarthritis treatment was proposed as one example application. Other potential applications could be studied with minimal changes such as gait retraining to prevent running injuries [41] and gait rehabilitation [42], [43]. This study validated the mapping-based dosage selection method for two gait parameters.…”

Ankle resistance with a unilateral soft exosuit increases plantarflexor effort during pushoff in unimpaired individuals

“…The MDC has been used to determine clinical significance for changes in poststroke gait, and thus these results suggest the feasibility of the resistive exosuit paradigm for increasing plantarflexor effort in people poststroke. Another recent study found that in the presence of plantarflexor resistance, healthy individuals reduced ankle joint range of motion and peak plantarflexion angle [ 32 ]. While our findings are consistent with these outcomes, we observed only slight reductions in peak plantarflexion angle (2–4°) when applying up to 300 N of force compared to the approximately 10° seen in prior work when applying 10 N [ 32 ].…”

“…1 B). One-minute subdivisions were chosen as this is a common timeframe for analysis in exosuit work [ 32 , 50 ].…”

“…These devices are transparent when in the “slack” mode, during which the cables are not under tension, and induce minimal changes in gait from wearing the device alone [ 30 , 31 ]. A recent study showed that using a soft unilateral exosuit to apply constant, low-force resistance at the ankle from late stance to mid-swing in healthy individuals led to changes in joint range of motion [ 32 ]. Another study found that walking overground with a passive, compliant, ankle resistive device resulted in adaptation of ankle joint velocity during the period of resistance, and posited that these changes may have implications for training increased plantarflexor muscle activity [ 33 ].…”

“…Conventional resistance training methods further typically vary task intensity through progressive schemes, such as increasing the band stiffness or adding higher weights to the foot over time [ 9 , 12 ]. In contrast, most existing literature investigating joint and stance specific resistance with wearable devices do not systematically vary the applied resistance force magnitude [ 27 , 32 – 36 ], and thus there is little knowledge of how resistance magnitude should be set to modulate intensity at the ankle. People poststroke and healthy individuals often rely on proximal joints or the contralateral limb to compensate for ankle weakness [ 37 ] or for high intensity tasks such as incline walking [ 20 , 38 ].…”