Seok Hun Kim

Novel Gait Adaptation and Neuromotor Training Results Using an Active Leg Exoskeleton

The gait of every adult is unique and expected to be ingrained within the neuromuscular system. The major scientific question that we ask in this paper if it is possible to alter the gait of healthy individuals using special purpose design of robots and training paradigms. This paper describes novel experimental results with an active leg exoskeleton (ALEX) and a force-field controller (FFC) developed for neuromotor training of gait and rehabilitation of patients with walking disabilities. ALEX is a motorized leg orthosis having a total of 7 DOFs with hip and knee actuated in the sagittal plane. The FFC applies forces on the foot to help the leg move on a desired trajectory. The interaction forces between the subject and the orthosis are designed to be ¿assist-as-needed¿ for safe and effective gait training. Simulations and experimental results with the FFC are presented. Experiments have been performed on six healthy subjects walking on a treadmill. It was shown that a healthy subject could be retrained in about 45 min with ALEX to walk on a treadmill with a considerably altered gait. In the coming months, this powered orthosis will be used for gait training of stroke patients.

Gait and balance in adults with Friedreich's ataxia

Friedreichs ataxia (FA) is an autosomal recessive, neurodegenerative disease characterized by progressive muscle weakness and sensory loss, balance deficits, and gait ataxia. Gait and balance impairments become worse as the disease progresses, but limited research has quantitatively assessed these deficits in adults with FA. The purpose of this study was to analyze gait and balance in this population and investigate the relationship between these variables. Eight subjects with genetically confirmed FA (29.4±9.0 years) and eight healthy, matched control subjects (29.6±9.1 years) participated in this study. Spatiotemporal gait parameters were examined using the GAITRite Walkway System while balance was examined utilizing the Biodex Balance System SD and the Berg Balance Scale (BBS). The FA group exhibited approximately 50% slower gait velocity and 32% shorter step and stride lengths compared to the control group for both comfortable and fast walking (p<0.001). Further, stride length variability in the FA group was 3.4 and 2.7 times that of controls for comfortable and fast walking, respectively (p<0.01). Subjects with FA took 72% longer to complete the limits of stability (LOS) test and attained an overall directional control score that was 50% that of controls (p<0.05). Lastly, age at FA symptom onset correlated with stride length variability during fast walking (p<0.05), and BBS and LOS test scores correlated with stride length variability during both comfortable and fast walking (p<0.05). Results demonstrate that adults with FA have significantly impaired gait and balance and several measures of these impairments are correlated.

STAIR ASCENT AND RAMP GAIT TRAINING WITH THE GENIUM KNEE

Accepted May 1, 2013. Address correspondence to M. Jason Highsmith, School of Physical Therapy & Rehabilitation Sciences, Morsani College of Medicine, University of South Florida, 12901 Bruce B. Downs Blvd., MDC 077, Tampa, FL 33612-4799, USA. Tel: +1-813-974-3806 (office); Fax: +1-813-974-8915; E-mail: mhighsmi@health.usf.edu Technology and Innovation, Vol. 15, pp. 349–358, 2014 1949-8241/14

A Method for Training Step-Over-Step Stair Descent Gait With Stance Yielding Prosthetic Knees: A Technical Note

90.00 + .00 Printed in the USA. All rights reserved. DOI: http://dx.doi.org/10.3727/194982413X13844488879267 Copyright  2014 Cognizant Comm. Corp. E-ISSN 1949-825X www.cognizantcommunication.com

Multicomponent exercise for physical fitness of community-dwelling elderly women.

ABSTRACT Limited information is available concerning stair descent training for transfemoral amputees using prosthetic knees. Literature describing stair descent training techniques are predominantly available for the step-to-step stair descent method. A thoroughly descriptive technique for training prosthetic knee users to reciprocally descend stairs, using a step-over-step pattern is not available. The purpose of this technical note is to describe a procedure for training stance-yielding prosthetic knee users how to descend stairs using a reciprocal, step-over-step pattern. The technique describes stair setup, safety considerations including hand railing, use of a gait belt, guarding techniques and a one versus two therapist technique. Nineteen subjects were initially trained in this technique, and all subjects demonstrated the ability to reciprocally descend stairs after training. Reciprocal step-over-step stair descent is not appropriate for all transfemoral amputees; however, we recommend considering the supervised, therapeutic application of this technique for all transfemoral amputees using stance yielding prosthetic knees. We suggest that practicing this technique might improve a prosthetic knee users overall functional performance such as their ability to utilize stumble recovery during a missed step, to transition more symmetrically from stand to sit and to utilize knee flexion during the loading response of gait.

Longitudinal gait and balance decline in Friedreich’s Ataxia: A pilot study

[Purpose] The purpose of this study was to identify whether a 4-week multicomponent exercise program could improve the level of physical fitness of community-dwelling elderly women. [Subjects and Methods] Twenty-two healthy community-dwelling elderly women were randomly allocated to either an experimental or a control group. Experimental subjects performed a multicomponent exercise program that consisted of balance, strengthening, and stretching exercises for 4 weeks, whereas the control subjects did not perform any specific exercise. The subjects’ level of physical fitness was assessed prior to and after training using the Senior Fitness Test which assesses muscle strength, flexibility, dynamic balance/agility, aerobic endurance, and body composition. [Results] Subjects in the experimental group showed significant improvements in lower and upper body strength, lower and upper body flexibility, dynamic balance/agility following training, but not in aerobic endurance or body composition. Significant group differences were shown in lower and upper body strength, lower body flexibility, and dynamic balance/agility. [Conclusion] The results suggest that a multicomponent training program that consists of balance, strengthening, and stretching exercises is a relevant intervention for the improvement of the level of physical fitness of community-dwelling elderly women.

Development and feasibility study of a sensory-enhanced robot-aided motor training in stroke rehabilitation

INTRODUCTION Friedreichs Ataxia (FA) is a devastating, progressive, neurodegenerative disease. Objective measures that detect changes in neurological function in FA patients are needed to facilitate therapeutic clinical trials. The purpose of this pilot study was to analyze longitudinal changes in gait and balance in subjects with FA using the GAITRite Walkway System® and Biodex Balance System™, respectively, and to test the ability of these measures to detect change over time compared to the Friedreichs Ataxia Rating Scale (FARS). METHODS This was a 24-month longitudinal study comparing ambulatory FA subjects with age- and gender-matched, healthy controls. Eight FA subjects and 8 controls were tested at regular intervals using the GAITRite and Biodex Balance systems and the FARS. RESULTS In the FA group, comfortable and fast gait velocity declined 8.0% and 13.9% after 12 months and 24.1% and 30.3% after 24 months, respectively. Postural stability indices increased in FA subjects an average of 41% from baseline to 24 months, representing a decline in balance. Subjects with FA also demonstrated a 17.7% increase in FARS neurological exam scores over 24 months. There were no changes in gait or balance variables in controls. In the FA group, multiple gait and balance measures correlated significantly with FARS neurological exam scores. CONCLUSIONS The GAITRite and Biodex Balance systems provided objective and clinically relevant measures of functional decline in subjects with FA that correlated significantly with performance measures in the FARS. Gait velocity may be an important objective measure to identify disease progression in adults with FA.

Knee orthosis with variable stiffness and damping that simulates hemiparetic gait

Functional impairment of the upper limb is a major challenge faced by many stroke survivors. The present study aimed at developing a novel sensory-enhanced robot-aided motor training program and testing its feasibility in stroke rehabilitation. A specially designed robot handle was developed as an attachment to the Inmotion2 robotic system. This handle provided sensory stimulation through pins connected to small servo motors inside the handle. Vibration of the pins was activated during motor training once pressure on the handle reached a certain threshold indicating an active motion of the study subject. Nine chronic stroke survivors were randomly assigned to either a sensory-enhanced robot-aided motor training group (SERMT) or robot-aided motor training only group (RMT). All participants underwent a 6-week motor training program, performing target reaching movements with the specialized handle with or without vibration stimulation during training. Motor Status (MS) scores were measured for functional outcome prior to and after training. The results showed significant improvement in the total MS scores after training in both experimental groups. However, MS sub-scores for the shoulder/elbow and the wrist/hand increased significantly only in the SERMT group (p<0.05). Future studies are required to confirm these preliminary findings.

Correlations between residual limb length and joint moments during sitting and standing movements in transfemoral amputees

Individuals with unilateral stroke have neuromuscular weakness or paralysis on one side of the body caused by some muscles disengaging and others overexciting. Hyperextension of the knee joint and complete lack of plantar flexion of the ankle joint are common symptoms of stroke. This paper focuses on the creation and implementation of a small, lightweight, and adjustable orthotic device to be positioned around the knee of an able-bodied person to simulate hemiparetic gait. Force and range of motion data from able-bodied subjects fitted with the orthosis, inducing hemiparetic gait, was collected using the Computer Assisted Rehabilitation ENvironment (CAREN) system. The four parameters that the design focused on are damping, catch, hysteresis, and stiffness. The main goal of the project was to discern whether this device could be utilized as a viable research instrument to simulate hemiparetic gait. It was hypothesized that the device has the potential to be utilized in the future as a rehabilitation device for people with stroke since it has been designed to induce larger knee flexion as an after effect. A comparison between how the dominant leg was affected by the orthosis and how the non-dominant leg was affected was investigated as well. The results show that the device affected the velocities, knee angles, and force profiles of the subjects gait.

Crutch tip for swing-through crutch walking control based on a kinetic shape

Background and aim: Longer residual limb lengths provide an increased lever arm. Longer residual limbs may produce increased joint moments; the two may be correlated. These correlations have not been evaluated in transfemoral amputees during transitional movements. Correlations between residual limb length and involved side joint moment could contribute to justification supporting maximal residual limb length preservation. This study investigated possible correlations between hip or knee moment and residual limb length. Technique: Hip and knee joint moments were determined while 21 transfemoral amputees performed sitting and standing movements and then evaluated for correlation with residual limb length. Discussion: Residual limb length was not correlated with either knee or involved side hip moments during sit to stand or stand to sit. Conversely, weak inverse correlations (p < 0.05) existed between sound hip moment magnitude and residual limb length. These correlations suggest that in community ambulating transfemoral amputees, longer residual limb length could decrease sound hip kinetic burden during transitional movement. Beyond correlations between residual limb length and sound hip transitional movement kinetics, there are other considerations in determining residual limb length during amputation. Clinical relevance This study examines relationships between lower limb joint moments and residual limb length related to sit-to-stand and stand-to-sit activities. The results have implications for amputation surgery and rehabilitation.