Abstract
Background: Robot-assisted gait therapy is a fast-growing field in pediatric neuro-rehabilitation. Understanding how these constantly developing technologies work is a prerequisite for shaping clinical application. For the Lokomat, two new features are supposed to increase patients' movement variability and should enable a more physiological gait pattern: Path Control and FreeD. This work provides a secondary data analysis of a previously published study, and looks at surface electromyography (sEMG) during Guidance Force walking and six sub-conditions of Path Control and FreeD.Objective: The aim was to evaluate different levels of kinematic freedom on the gait pattern of pediatric patients by modulating settings of Path Control and FreeD.Methods: Fifteen patients (mean age 16 ± 2 years) with neurological gait disorders completed the measurements. We analyzed sEMG amplitudes and the correlation of sEMG patterns with normative data of five leg muscles during walking conditions with increasing kinematic freedom in the Lokomat. The new outcome measure of inter-step similarity is introduced as a proxy for walking task complexity.Results: Within Path Control, sub-conditions showed significantly higher sEMG amplitudes in a majority of muscles with increasing kinematic freedom, and correlations with the norm pattern increased with increasing kinematic freedom. FreeD sub-conditions generally showed low or even negative correlations with the norm pattern and a lower inter-step similarity compared to Guidance Force.Conclusions: In general, this work highlights that the new hard- and software approaches of the Lokomat influence muscle activity differently. An increase of kinematic freedom of the walking condition led to an increase in muscular effort (Path Control) or to a higher step variability (FreeD) which can be interpreted as an increased task complexity of this condition. The inter-step similarity could be a helpful tool for the therapist to estimate the patient's state of strain.
Highlights
For several years robot-assisted therapy devices have established their place in a wide range of interdisciplinary therapies in neuro-rehabilitation
Path Control Sub-conditions When focusing on sub-conditions of Path Control, the highest muscle activity was observable with a support force of 0%, which is the sub-condition with the maximum kinematic freedom in this condition
The results show that an increase in kinematic freedom led to a change in heart rate and muscle activity in all muscles except for the M. gastrocnemius lateralis (Friedman tests: M. rectus femoris: χ2 = 19.6, p < 0.001; M. vastus medialis: χ2 = 9.7, p = 0.008; M. biceps femoris: χ2 = 10.1, p = 0.006; M. tibialis anterior: χ2 = 8.8, p = 0.012; M. gastrocnemius lateralis: χ2 = 3.5, p = 0.17; Heart rate: χ2 = 17.7, p < 0.001)
Summary
Robot-assisted therapy devices have established their place in a wide range of interdisciplinary therapies in neuro-rehabilitation. The population pool is small and shows a very heterogeneous clinical appearance To address this issue, a group of European experts recently published generalizable, practical recommendations (AurichSchuler et al, 2015) for the application of the pediatric Lokomat (Hocoma AG, Volketswil, Switzerland), which is one of the most sold robotic therapy devices worldwide. Other recommendations focus on common robotic therapy devices for children and adolescents undergoing neurorehabilitation (van Hedel and Aurich-Schuler, 2016) Both publications point out that broad practical knowhow is essential, especially for the rehabilitation of young patients. Robot-assisted gait therapy is a fast-growing field in pediatric neuro-rehabilitation Understanding how these constantly developing technologies work is a prerequisite for shaping clinical application. This work provides a secondary data analysis of a previously published study, and looks at surface electromyography (sEMG) during Guidance Force walking and six sub-conditions of Path Control and FreeD
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