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Peraleda de la Mata, Spain

Del-Ama A.J.,Biomechanics and Technical Aids Unit | Del-Ama A.J.,Bioengineering Group | Gil-Agudo A.,Biomechanics and Technical Aids Unit | Pons J.L.,Bioengineering Group | Moreno J.C.,Bioengineering Group
Journal of NeuroEngineering and Rehabilitation

Robotic and functional electrical stimulation (FES) approaches are used for rehabilitation of walking impairment of spinal cord injured individuals. Although devices are commercially available, there are still issues that remain to be solved. Control of hybrid exoskeletons aims at blending robotic exoskeletons and electrical stimulation to overcome the drawbacks of each approach while preserving their advantages. Hybrid actuation and control have a considerable potential for walking rehabilitation but there is a need of novel control strategies of hybrid systems that adequately manage the balance between FES and robotic controllers. Combination of FES and robotic control is a challenging issue, due to the non-linear behavior of muscle under stimulation and the lack of developments in the field of hybrid control. In this article, a cooperative control strategy of a hybrid exoskeleton is presented. This strategy is designed to overcome the main disadvantages of muscular stimulation: electromechanical delay and change in muscle performance over time, and to balance muscular and robotic actuation during walking.Experimental results in healthy subjects show the ability of the hybrid FES-robot cooperative control to balance power contribution between exoskeleton and muscle stimulation. The robotic exoskeleton decreases assistance while adequate knee kinematics are guaranteed. A new technique to monitor muscle performance is employed, which allows to estimate muscle fatigue and implement muscle fatigue management strategies. Kinesis is therefore the first ambulatory hybrid exoskeleton that can effectively balance robotic and FES actuation during walking. This represents a new opportunity to implement new rehabilitation interventions to induce locomotor activity in patients with paraplegia.Acronym list: 10mWT: ten meters walking test; 6MWT: six minutes walking test; FSM: finite-state machine; t-FSM: time-domain FSM; c-FSM: cycle-domain FSM; FES: functional electrical stimulation; HKAFO: hip-knee-ankle-foot orthosis; ILC: iterative error-based learning control; MFE: muscle fatigue estimator; NILC: Normalized stimulation output from ILC controller; PID: Proportional-Integral-derivative Control; PW: Stimulation pulse width; QUEST: Quebec User Evaluation of Satisfaction with assistive Technology; SCI: Spinal cord injury; TTI: torque-time integral; VAS: Visual Analog Scale. © 2014 del-Ama et al.; licensee BioMed Central Ltd. Source

del-Ama A.J.,Biomechanics and Technical Aids Unit | Gil-Agudo A.,Biomechanics and Technical Aids Unit | Pons J.L.,Bioengineering Group | Moreno J.C.,Bioengineering Group
Frontiers in Human Neuroscience

Locomotor training has proved to provide beneficial effect in terms of mobility in incomplete paraplegic patients. Neuroprosthetic technology can contribute to increase the efficacy of a training paradigm in the promotion of a locomotor pattern. Robotic exoskeletons can be used to manage the unavoidable loss of performance of artificially driven muscles. Hybrid exoskeletons blend complementary robotic and neuro-prosthetic technologies. The aim of this pilot study was to determine the effects of hybrid gait training in three case studies with persons with incomplete spinal cord injury (iSCI) in terms of locomotion performance during assisted gait, patient-robot adaptations, impact on ambulation and assessment of lower limb muscle strength and spasticity. Participants with iSCI received interventions with a hybrid bilateral exoskeleton for 4 days. Assessment of gait function revealed that patients improved the 6 min and 10 m walking tests after the intervention, and further improvements were observed 1 week after the intervention. Muscle examination revealed improvements in knee and hip sagittal muscle balance scores and decreased score in ankle extensor balance. It is concluded that improvements in biomechanical function of the knee joint after the tested overground hybrid gait trainer are coherent with improvements in gait performance. © 2014 del-Ama, Gil-Agudo, Pons and Moreno. Source

Gil-Agudo A.,Biomechanics and Technical Aids Unit | Perez-Nombela S.,Biomechanics and Technical Aids Unit | Perez-Rizo E.,Biomechanics and Technical Aids Unit | Del Ama-Espinosa A.,Biomechanics and Technical Aids Unit | And 2 more authors.
Disability and Rehabilitation

Purpose: This is a pilot study with the aim to highlight the use of kinematic and kinetic analyses as an adjunct to the assessment of individual patients with central cord syndrome (CCS) and hemisection or Brown-Séquard syndrome (BSS) and to discuss their possible consequences for clinical management. Methods: The sample studied consisted of 17 patients with CCS, 13 with BSS and 20 control subjects (control group (CG)). Data were obtained using a three-dimensional motion analysis system and two force plates. Gait differences were compared between CCS, BSS walking at a self-selected speed and CG at both a self-selected and a similar speed to that of the patient groups. Results: The most relevant findings involved the knee and ankle, especially in the sagittal plane. In patients with CCS, knee flexion at initial contact was increased with respect to those in the BSS group (p < 0.01). The ankle in the BSS group made initial contact with a small degree of plantar flexion. Conclusion: The use of gait biomechanical analysis to detect underlying impairments can help the physician to set a specific rehabilitation program in each CCS and BSS walking patient. In this group of patients, rehabilitation treatment should aim to improve gait control and optimise ankle positioning at initial contact.Implications for RehabilitationIn this study, gait differences between patients with CSS and BSS were evaluated with biomechanical equipment.The most remarkable differences were found in the knee and ankle sagittal plane due to ankle position at initial contact.In this group of patients, rehabilitation treatment should aim to improve gait control and to get a better ankle positioning at initial contact. © 2013 Informa UK Ltd. All rights reserved. Source

Gil-Agudo A.,Biomechanics and Technical Aids Unit | Perez-Nombela S.,Biomechanics and Technical Aids Unit | Forner-Cordero A.,University of Sao Paulo | Perez-Rizo E.,Biomechanics and Technical Aids Unit | And 2 more authors.
Journal of NeuroEngineering and Rehabilitation

Background: Central cord syndrome (CCS) is considered the most common incomplete spinal cord injury (SCI). Independent ambulation was achieved in 87-97% in young patients with CCS but no gait analysis studies have been reported before in such pathology. The aim of this study was to analyze the gait characteristics of subjects with CCS and to compare the findings with a healthy age, sex and anthropomorphically matched control group (CG), walking both at a self-selected speed and at the same speed. Methods. Twelve CCS patients and a CG of twenty subjects were analyzed. Kinematic data were obtained using a three-dimensional motion analysis system with two scanner units. The CG were asked to walk at two different speeds, at a self-selected speed and at a slower one, similar to the mean gait speed previously registered in the CCS patient group. Temporal, spatial variables and kinematic variables (maximum and minimum lower limb joint angles throughout the gait cycle in each plane, along with the gait cycle instants of occurrence and the joint range of motion - ROM) were compared between the two groups walking at similar speeds. Results: The kinematic parameters were compared when both groups walked at a similar speed, given that there was a significant difference in the self-selected speeds (p < 0.05). Hip abduction and knee flexion at initial contact, as well as minimal knee flexion at stance, were larger in the CCS group (p < 0.05). However, the range of knee and ankle motion in the sagittal plane was greater in the CG group (p < 0.05). The maximal ankle plantar-flexion values in stance phase and at toe off were larger in the CG (p < 0.05). Conclusions: The gait pattern of CCS patients showed a decrease of knee and ankle sagittal ROM during level walking and an increase in hip abduction to increase base of support. The findings of this study help to improve the understanding how CCS affects gait changes in the lower limbs. © 2011 Gil-Agudo et al; licensee BioMed Central Ltd. Source

del-Ama A.J.,Biomechanics and Technical Aids Unit | del-Ama A.J.,Bioengineering Group | Koutsou A.D.,Bioengineering Group | Moreno J.C.,Bioengineering Group | And 3 more authors.
Journal of Rehabilitation Research and Development

Different approaches are available to compensate gait in persons with spinal cord injury, including passive orthoses, functional electrical stimulation (FES), and robotic exoskeletons. However, several drawbacks arise from each specific approach. Orthotic gait is energy-demanding for the user and functionally ineffective. FES uses the muscles as natural actuators to generate gait, providing not only functional but also psychological benefits to the users. However, disadvantages are also related to the early appearance of muscle fatigue and the control of joint trajectories. Robotic exoskeletons that provide joint moment compensation or substitution to the body during walking have been developed in recent years. Significant advances have been achieved, but the technology itself is not mature yet because of many limitations related to both physical and cognitive interaction as well as portability and energy-management issues. Meanwhile, the combination of FES technology and exoskeletons has emerged as a promising approach to both gait compensation and rehabilitation, bringing together technologies, methods, and rehabilitation principles that can overcome the drawbacks of each individual approach. This article presents an overview of hybrid lower-limb exoskeletons, related technologies, and advances in actuation and control systems. Also, we highlight the functional assessment of individuals with spinal cord injury. Source

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