A two-degree-of-freedom motor-powered gait orthosis for spinal cord injury patients

Effects of lower limb exoskeleton gait orthosis compared to mechanical gait orthosis on rehabilitation of patients with spinal cord injury: A systematic review and future perspectives

OBJECTIVE

We aimed to systematically evaluate the walking efficiency of lower limb exoskeleton gait orthosis and mechanical gait orthosis in patients with spinal cord injury.

DATA SOURCES

Databases searched included: Web of Science, MEDLINE, Cochrane Library and Google Scholar.

STUDY SELECTION

Articles published in English from 1970 to 2022 investigating the impact of lower limb exoskeleton gait orthosis versus mechanical gait orthosis on gait outcomes in patients with spinal cord injury were considered.

DATA EXTRACTION

Two researchers independently extracted data and filled out predesigned forms. Information including authors, year of study, methodological quality, participant characteristics, intervention and comparison details, outcomes and results. The primary outcomes were kinematic data; the secondary outcomes were clinical tests.

DATA SYNTHESIS

Data synthesis using meta-analysis was not possible due to the diversity of study designs, methodologies, and outcome measures.

RESULTS

A total of 11 trials and 14 types of orthotics were included. The information gathered generally supported the gait improving effects of lower limb exoskeleton gait orthosis and mechanical gait orthosis in both kinematic data and clinical tests among patients with spinal cord injury.

CONCLUSIONS

This systematic review compared walking efficiency of patients with spinal cord injury wearing powered exoskeleton gait orthosis and non-powered mechanical gait orthosis. Due to the limited quality and quantity of the included studies, more high-quality studies are needed to verify the above conclusions. Future research should focus on improving trial quality and comprehensive parametric analysis of subjects with different physical conditions.

TWIICE One powered exoskeleton: effect of design improvements on usability in daily life as measured by the performance in the CYBATHLON race

Background

Spinal cord injury leading to paraplegia affects the mobility and physiological well-being of one in a thousand people. Powered exoskeletons can temporarily restore the ability to walk. Their relevance in daily life is still limited because of low performance beyond ground that is even. CYBATHLON is an international competition promoting improvements in assistive technology. In this article, we present the latest design and results of testing of TWIICE One version 2018, one of the competing devices in the 2020 race.

Methods

A person with a motor-complete spinal cord injury at thoracic level T10 participated as race pilot. Training ahead of the race took place over one week at a rate of 2 h per day. The time to perform each of the seven tasks of the competition was recorded together with the number of repetitions. Performance is compared over the training period and against the 2016 race results.

Results

Progression was observed in all tasks and accounted for by both user training and technology improvements. Final competition rank was second out of seven participating teams, with a record time of 4′40". This represents an average improvement of 40% with respect to comparable obstacles of the 2016 race, explaining the two ranks of improvement since then.

Conclusion

These results help understand which features had a positive impact on the real-life performance of the device. Understanding how design affects performance is key information to create devices that really improve the life of people living with paraplegia.

Ergonomic Design and Performance Evaluation of H-Suit for Human Walking

A soft exoskeleton for the hip flexion, named H-Suit, is developed to improve the walking endurance of lower limbs, delay muscle fatigue and reduce the activation level of hip flexors. Based on the kinematics and biomechanics of the hip joints, the ergonomic design of the H-Suit system is clearly presented and the prototype was developed. The profile of the auxiliary forces is planned in the auxiliary range where the forces start at the minimum hip angle, reach the maximum (120 N) and end at 90% of each gait cycle. The desired displacements of the traction unit which consist of the natural and elastic displacements of the steel cables are obtained by the experimental method. An assistance strategy is proposed to track the profile of the auxiliary forces by dynamically adjusting the compensation displacement Lc and the hold time Δt. The influences of the variables Lc and Δt on the natural gaits and auxiliary forces have been revealed and analyzed. The real profile of the auxiliary forces can be obtained and is consistent with the theoretical one by the proposed assistance strategy. The H-Suit without the drive unit has little effect on the EMG signal of the lower limbs. In the powered condition, the H-Suit can delay the muscle fatigue of the lower limbs. The average rectified value (ARV) slope decreases and the median frequency (MNF) slope increases significantly. Wearing the H-Suit resulted in a significant reduction of the vastus lateralis effort, averaged over subjects and walking speeds, of 13.3 ± 2.1% (p = 2 × 10−5).

Effect of Gait Training Program with Mechanical Exoskeleton on Body Composition of Paraplegics

Purpose

To identify the effect of a 52-weeks gait training program with an exoskeletal body-powered gait orthosis on the body composition of paraplegics.

Patients and Methods

Ten subjects with spinal cord injury at the thoracolumbar spine level for more than 2 years participated and were divided into exercise (n=5) and nonexercise (n=5) groups. A gait training program comprising stages 1–6 with customized exoskeletal body-powered gait orthosis was conducted for 52-weeks. A six-stage gait training program was conducted to manage the body composition and prevent obesity, and the changes in the body composition before and after the program were determined through bioelectrical impedance analysis.

Results

No significant changes in weight, fat-free mass (kg), lean body mass (kg), and percent fat mass (%) are seen in the exercise group before and after the 52-weeks program. However, fat-free mass (pre = 47.3± 6.5, post = 44.3 ± 5.4, kg), lean body mass (pre = 45.2 ± 6.3, post = 42.3±5.2, kg), and percent fat mass (pre = 30.1 ± 12.1, post = 40.9 ± 9.1, kg) show significant changes (p < 0.05) in the nonexercise group. In the nonexercise group, among lean body mass changes over 52-weeks in the upper limbs (−31%), trunks (−9.7%), and lower limbs (−8.6%), upper limbs exhibit the most significant decrease (p < 0.05).

Conclusion

The gait training program with exoskeletal body-powered gait orthosis has a positive effect on fat management in the whole body and lean body mass loss in paraplegics. Furthermore, it is effective in preventing continuous muscle loss and in maintaining health by reducing body fat. Body composition measurements with bioelectrical impedance analysis for paraplegics can be applied in various clinical areas and can be combined with various arbitration methods such as rehabilitation program.

Kinematic and electromyography analysis of paraplegic gait with the assistance of mechanical orthosis and walker

Objective: To investigate the kinematics, functional sub-tasks, and excitation levels of the trunk and upper extremity muscles of paraplegic subjects during walker-assisted locomotion. Design: Retrospective cross-sectional study. Setting: Gait analysis laboratory. Participants: Eight individuals with spinal cord injury at T12, lower extremity motor score less than 4, and capable of walking independently with the assistance of ankle-foot orthosis and walker. Main Outcome Measures: Kinematics of pelvis, trunk, shoulder and elbow; trajectory of center of mass; and electromyography (EMG) activity of trunk and upper extremity muscles during gait. Results: Four subtasks were characterized for each locomotion step, based on the kinetics and kinematics data: (1) balance adjustment, (2) walker propulsion, (3) leg raising, and (4) leg swing. The latter two involved large lateral maneuvres by the trunk and pelvis and appeared to be the most skill- and muscle activity-demanding subtasks. The main muscles contributing into these subtasks were the ipsilateral paraspinal and abdominal muscles, as well as the contralateral scapulothoracic and shoulder girdle muscles, with EMG intensities significantly higher than their minimum mean intensities (P < 0.05) and those of the contralateral side (P < 0.05). Conclusions: Our results provide more insight into the functional sub-tasks and muscular demands of walker-assisted paraplegic gait that can help to design appropriate muscle strengthening programs, as well as developing more effective gait orthoses.

Design and Analysis of a Novel Lightweight, Energy Economic Powered Knee Orthotic Device

The task of a powered knee orthotic device (PKOD) is to assist the knee joint so that its natural behavior can be restored. The key features of a PKOD that may help to regain such characteristics are low power consumption, fast response, compactness, and lightweight. This study proposes a novel design of PKOD, where we have focused on the betterment of the mentioned features with the help of a new mechanism, namely a four-bar controlled compliance actuator (FCCA). In FCCA, instead of using the widely used screw transmission mechanism, a four-bar mechanism is used to modify the joint's angular deviation and stiffness. The main advantages of using FCCA over other existing mechanisms are to reduce the power consumption by amplification of input motor torque and to achieve a faster response at the same time, and these are achieved by utilizing a simple four-bar mechanism. In the proposed design, FCCA controls both the stiffness of the artificial knee joint using a compliance mechanism as well as knee flexion with the help of a pulley arrangement. A three-dimensional (3D)-printed prototype of the proposed design has been developed, after optimizing the inherent design parameters. Simulation and experimental analysis are carried out in order to justify the performance of the proposed PKOD. The results have shown strong agreement with that obtained using analytical study and optimization. Moreover, the torque amplification is achieved, as desired.

Lower limb sagittal kinematic and kinetic modeling of very slow walking for gait trajectory scaling

Lower extremity powered exoskeletons (LEPE) are an emerging technology that assists people with lower-limb paralysis. LEPE for people with complete spinal cord injury walk at very slow speeds, below 0.5m/s. For the able-bodied population, very slow walking uses different neuromuscular, locomotor, postural, and dynamic balance control. Speed dependent kinetic and kinematic regression equations in the literature could be used for very slow walking LEPE trajectory scaling; however, kinematic and kinetic information at walking speeds below 0.5 m/s is lacking. Scaling LEPE trajectories using current reference equations may be inaccurate because these equations were produced from faster than real-world LEPE walking speeds. An improved understanding of how able-bodied people biomechanically adapt to very slow walking will provide LEPE developers with more accurate models to predict and scale LEPE gait trajectories. Full body motion capture data were collected from 30 healthy adults while walking on an instrumented self-paced treadmill, within a CAREN-Extended virtual reality environment. Kinematic and kinetic data were collected for 0.2 m/s-0.8 m/s, and self-selected walking speed. Thirty-three common sagittal kinematic and kinetic gait parameters were identified from motion capture data and inverse dynamics. Gait parameter relationships to walking speed, cadence, and stride length were determined with linear and quadratic (second and third order) regression. For parameters with a non-linear relationship with speed, cadence, or stride-length, linear regressions were used to determine if a consistent inflection occurred for faster and slower walking speeds. Group mean equations were applied to each participant's data to determine the best performing equations for calculating important peak sagittal kinematic and kinetic gait parameters. Quadratic models based on walking speed had the strongest correlations with sagittal kinematic and kinetic gait parameters, with kinetic parameters having the better results. The lack of a consistent inflection point indicated that the kinematic and kinetic gait strategies did not change at very slow gait speeds. This research showed stronger associations with speed and gait parameters then previous studies, and provided more accurate regression equations for gait parameters at very slow walking speeds that can be used for LEPE joint trajectory development.

Design and analysis of an original powered foot clearance creator mechanism for walking in patients with spinal cord injury

BACKGROUND

The aim of this study was to assess the performance of an original powered foot clearance creator (PFCC) mechanism worn in conjunction with an isocentric reciprocal gait orthosis (IRGO) and evaluate its effect on trunk compensatory movements and spatiotemporal parameters in nine healthy subjects.

METHOD

A PFCC motorized mechanism was designed that incorporated twin sole plates, the movements of which enabled increased toe to floor clearance during swing phase. A prototype was constructed in combination with an IRGO, and hence was re-named as an IRGO-PFCC orthosis. The effects of IRGO-PFCC usage on the spatiotemporal parameters and trunk compensatory movements during walking were then analyzed under two conditions, firstly with the PFCC 'active' i.e., with the motorized device functioning, and secondly inactive, where floor clearance was standard.

RESULTS

Ambulating with IRGO-PFCC orthosis resulted in reduction in the spatiotemporal parameters of gait (speed of walking, cadence and stride length) in nine healthy subjects. Walking with IRGO-PFCC orthosis led to significant differences in lateral (p = .007) and vertical (p = .008) trunk compensatory movements. In other words, through using IRGO-PFCC orthosis, the lateral and vertical trunk compensatory movements decreased by 51.32% and 42.7%, respectively.

CONCLUSION

An adapted PFCC mechanism, with a relatively small motor and power supply could effectively increase toe to floor clearance during swing phase and thereby decrease trunk compensatory motions and potentially improve energy consumption. Implications for rehabilitations •The High rejection rates of reciprocal gait orthoses are related to the increasing in energy expenditure and burden loads on the upper limb joints during walking following trunk compensatory movements.•An original powered foot clearance creator mechanism was designed and constructed to assisting floor clearance capability and reduce trunk compensatory movements in subjects with spinal cord injury during swing phase of gait.•This original powered foot clearance creator mechanism by using moveable soleplates and motorized actuation could decrease the trunk compensatory motions during the ambulation of nine healthy subjects.•More experiments are needed to investigate this mechanism on trunk compensatory movements of SCI subjects.

Application of a paraplegic gait orthosis in thoracolumbar spinal cord injury

Paraplegic gait orthosis has been shown to help paraplegic patients stand and walk, although this method cannot be individualized for patients with different spinal cord injuries and functional recovery of the lower extremities. There is, however, a great need to develop individualized paraplegic orthosis to improve overall quality of life for paraplegic patients. In the present study, 36 spinal cord (below T4) injury patients were equally and randomly divided into control and observation groups. The control group received systematic rehabilitation training, including maintenance of joint range of motion, residual muscle strength training, standing training, balance training, and functional electrical stimulation. The observation group received an individualized paraplegic locomotion brace and functional training according to the various spinal cord injury levels and muscle strength based on comprehensive systematic rehabilitation training. After 3 months of rehabilitation training, the observation group achieved therapeutic locomotion in 8 cases, family-based locomotion in 7 cases, and community-based locomotion in 3 cases. However, locomotion was not achieved in any of the control group patients. These findings suggest that individualized paraplegic braces significantly improve activity of daily living and locomotion in patients with thoracolumbar spinal cord injury.

Effect of Orthotic Gait Training with Isocentric Reciprocating Gait Orthosis on Walking in Children with Myelomeningocele

Background: Mechanical orthoses are used to assist in standing and walking after neurological injury in children with myelomeningocele (MMC). Objectives: To evaluate the influence of orthotic gait training with an isocentric reciprocating gait orthosis (IRGO) on the kinematics and temporal-spatial parameters of walking in children with MMC. Methods: Five children with MMC were fitted with an IRGO. They walked at their own comfortable cadence using the orthosis. The hip joint angle, spatial temporal parameters, and compensatory motions were measured and analyzed. Results: Significant increases in walking speed and step length were demonstrated following orthotic gait training during walking with the IRGO. The sagittal plane hip range of motion was also significantly increased; however, the vertical and horizontal compensatory motions were significantly decreased. Conclusion: This study evaluated the influence of gait training with an IRGO on the kinematics and temporal spatial parameters in MMC children. The findings showed that orthotic gait training improved hip joint range of motion, increased walking speed and step length, and decreased lateral and vertical compensatory motions during level-ground walking trials.

Accelerometry-enabled measurement of walking performance with a robotic exoskeleton: a pilot study

Background

Clinical scores for evaluating walking skills with lower limb exoskeletons are often based on a single variable, such as distance walked or speed, even in cases where a host of features are measured. We investigated how to combine multiple features such that the resulting score has high discriminatory power, in particular with few patients. A new score is introduced that allows quantifying the walking ability of patients with spinal cord injury when using a powered exoskeleton.

Methods

Four spinal cord injury patients were trained to walk over ground with the ReWalk™ exoskeleton. Body accelerations during use of the device were recorded by a wearable accelerometer and 4 features to evaluate walking skills were computed. The new score is the Gaussian naïve Bayes surprise, which evaluates patients relative to the features’ distribution measured in 7 expert users of the ReWalk™. We compared our score based on all the features with a standard outcome measure, which is based on number of steps only.

Results

All 4 patients improved over the course of training, as their scores trended towards the expert users’ scores. The combined score (Gaussian naïve surprise) was considerably more discriminative than the one using only walked distance (steps). At the end of training, 3 out of 4 patients were significantly different from the experts, according to the combined score (p < .001, Wilcoxon Signed-Rank Test). In contrast, all but one patient were scored as experts when number of steps was the only feature.

Conclusion

Integrating multiple features could provide a more robust metric to measure patients’ skills while they learn to walk with a robotic exoskeleton. Testing this approach with other features and more subjects remains as future work.

The influence of orthosis options on walking parameters in spinal cord-injured patients: a literature review

OBJECTIVE

Orthoses for various joints sections are considered to greatly influence the gait function and energy expenditure in spinal cord-injured (SCI) patients. The aim of this review was to determine the influence of orthoses characteristics and options on the improvement of walking in patients with SCI.

METHODS

A search was performed using the Population Intervention Comparison Outcome (PICO) method, based on selected keywords; studies were identified electronically in the Science Direct, Google Scholar, Scopus, Web of Knowledge and PubMed databases. The Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) method was used to report the results. Assessment of the quality of all articles was performed based on the Physiotherapy Evidence Database (PEDro scale).

RESULTS

Twelve studies evaluated the effects of different hip joint options on walking parameters and energy expenditure. Five studies investigated the role of knee joint options on gait parameters and compensatory trunk motion. Only five studies analyzed modified ankle joints on gait parameters in SCI patients. Nine studies analyzed gait parameters in SCI patients as powered orthoses and exoskeleton. These studies had a low level of evidence according to the PEDro score (2/10).

CONCLUSION

The various joint types of orthoses appear to be critical in the improvement of walking in patients with SCI. In particular, 'user friendly' orthoses that support the related structure such as the hip joint with a reciprocating mechanism, activated knee joint and movable ankle joint with dorsiflexion assist enable SCI patients to optimize their walking pattern when wearing an orthoses system.

A biologically inspired soft exosuit for walking assistance

We present the design and evaluation of a multi-articular soft exosuit that is portable, fully autonomous, and provides assistive torques to the wearer at the ankle and hip during walking. Traditional rigid exoskeletons can be challenging to perfectly align with a wearer’s biological joints and can have large inertias, which can lead to the wearer altering their natural motion patterns. Exosuits, in comparison, use textiles to create tensile forces over the body in parallel with the muscles, enabling them to be light and not restrict the wearer’s kinematics. We describe the biologically inspired design and function of our exosuit, including a simplified model of the suit’s architecture and its interaction with the body. A key feature of the exosuit is that it can generate forces passively due to the body’s motion, similar to the body’s ligaments and tendons. These passively generated forces can be supplemented by actively contracting Bowden cables using geared electric motors, to create peak forces in the suit of up to 200 N. We define the suit–human series stiffness as an important parameter in the design of the exosuit and measure it on several subjects, and we perform human subjects testing to determine the biomechanical and physiological effects of the suit. Results from a five-subject study showed a minimal effect on gait kinematics and an average best-case metabolic reduction of 6.4%, comparing suit worn unpowered versus powered, during loaded walking with 34.6 kg of carried mass including the exosuit and actuators (2.0 kg on both legs, 10.1 kg total).

The efficiency of orthotic interventions on energy consumption in paraplegic patients: a literature review

Study design:This is a systematic literature review.Objectives:Different types of orthoses have been developed to enable and facilitate ambulation in individuals with paraplegia. However, their effect on energy consumption while ambulating is not clear. The objective of this review was to compare the energy expenditure required to walk with these devices.Methods:Using the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) method, and based on selected keywords and their composition according to the Population Intervention Comparison Outcome (PICO) method, a search was performed in Science Direct, Google Scholar, Scopus, Web of Knowledge and PubMed databases. The searches were restricted to papers published in the English language and were conducted during February 2014; the last access to the database was on 25 February 2014. A total of 24 articles were chosen for final evaluation.Results:Hybrid orthoses reduce energy consumption compared with mechanical orthoses when used for walking by paraplegic patients. The isocentric reciprocating gait orthosis has been shown to be more effective than other reciprocating orthoses in reducing energy consumption. Energy consumption when walking with powered orthoses (PO) and hybrid orthoses was also reduced compared with when walking with conventional orthoses.Conclusions:The hybrid orthoses and PO could be effective alternatives in rehabilitation for spinal cord injury patients to help improve the energy consumption.Spinal Cord advance online publication, 20 January 2015; doi:10.1038/sc.2014.227.

Evaluation of the performance of paraplegic subjects during walking with a new design of reciprocal gait orthosis

BACKGROUND

Spinal cord injury (SCI) influences a person's ability to stand and walk. Various orthoses have been developed to solve these standing and walking problems, however, patients still experience high energy consumption during walking and high forces on the upper limbs. A new reciprocal gait orthosis (RGO) was designed to address these problems. The aim of this study was to evaluate the performance of the new orthosis design with paraplegic subjects.

METHOD

Three paraplegic subjects with the lesion at level T12 and three able-bodied subjects were included in this study. Hip and pelvis range of motion and vertical ground reaction force were evaluated using the Qualysis motion analyzer system and a Kistler force plate. Energy consumption was measured with the Polar heart rate monitoring system. The differences between SCI individuals when walking with a Knee Ankle Foot Orthosis (KAFO) and the new RGO, and the differences between able-bodied and paraplegic subjects were evaluated by the use of paired sample and two sample t test, respectively.

RESULT

The results showed that energy consumption and gait analysis outcomes with new RGO orthosis were better than the KAFO. However, there was a large difference between paraplegic and able-bodied subjects while walking with the new orthosis.

CONCLUSION

The new RGO design performed better than a KAFO in terms of energy consumption, walking style and vertical ground reaction force. Therefore, it appears that RGO may be a useful orthosis for patients with paraplegia. Implications for Rehabilitation Walking and standing of the subjects with spinal cord injury (SCI) improve their physiological and physiological health. This study introduces a new type of orthosis design in order to improve the abilities of SCI subjects during walking and standing. It seems that the new design works better than available orthoses (KAFO).

Influence of orthotic gait training with powered hip orthosis on walking in paraplegic patients

OBJECTIVES

Gait training has been shown to improve the walking performance of spinal cord-injured (SCI) patients. The use of powered hip orthoses (PHO) during gait training is one approach which could potentially improve rehabilitative outcomes for such subjects. The aim of this study was therefore to evaluate the influence of a PHO on the kinematics and temporal-spatial parameters of walking by SCI patients.

METHODS

Four SCI patients participated in this study. Gait evaluation was performed at baseline and at 10 weeks following intervention with the use of a PHO and gait re-training. Walking speed, step length, vertical and horizontal compensatory motions and hip joint kinematics were analysed prior to and following the training regime.

RESULTS

Significant increases in walking speed and step length were demonstrated by the SCI patients when walking with the PHO following orthotic gait training. Sagittal plane hip range of motion also increased, but not significantly. However, vertical and horizontal compensatory motions decreased significantly.

CONCLUSIONS

Positive effects on the kinematics and temporal-spatial parameters of gait by SCI subjects were demonstrated following a period of gait training with a PHO. Further studies are therefore warranted to confirm their long term effects on the rehabilitation of SCI subjects.

IMPLICATIONS FOR REHABILITATION

Powered hip orthosis could be used by spinal cord injury patients. A major advantage of the orthotic gait training with powered hip orthosis was regeneration of hip movement closer to that of normal human walking. The orthotic gait training with the powered hip orthosis improved the kinematics and temporalspatial parameters in a spinal cord injury patient which also produced near-normal hip joint angle patterns during gait.

THE USE OF MOTION ANALYSIS SYSTEM AND ORTHOSIS IN PATIENTS WITH NEURO-MUSCULOSKELETAL DISORDERS

Background: Neuro-musculoskeletal disorders are a major source of physical disability involving more than one joint. Monitoring all joints during walking is achieved by using motion analysis system. There is limited evidence to show the suitability of motion analysis system to monitor neuro-musculoskeletal disorders. This research investigated the feasibility of this system to represent in patients with neuro-musculoskeletal disorders during walking. Method: Five groups of normal subjects with: knee osteoarthritis; avascular necrosis of hip joint; spinal cord injury and flat foot were recruited into this study. Kinetic and kinematic parameters were obtained by the use of motion analysis (Qualysis with seven cameras) and a Kistler force platform. The differences between gait parameters of normal and subjects with these disorders were examined using the independent t-tests. Paired t-test analysis was also used to determine the difference between walking with and without orthosis. Significant value was set at p ≤ 0.05. Results: There was a significant difference between the moment applied on the knee joint, the integral area between center of pressure (COP) and center of knee joint (COJ) graphs of normal and osteoarthritis (OA) subjects (p < 0.05). The area between COP and COJ of the ankle joint significantly differed between normal and flat foot subjects (p < 0.05). However, the force transmitted through the hip joint in subjects with Perthes did not differ significantly while walking with and without orthosis. In paraplegic subjects, the force applied on the limb and the mean values of gait parameters varied while walking with different orthoses which showed the feasibility of the system to monitor the performance of subjects with SCI disorder. Conclusion: The findings of the present study imply that the use of motion analysis is feasibility for assessing and monitoring neuro-musculoskeletal disorders. However, different parameters should be selected for various neuro-musculoskeletal disorders.

The efficiency of mechanical orthoses in affecting parameters associated with daily living in spinal cord injury patients: a literature review

OBJECTIVE

The most simple and common approach in providing standing and walking by subjects with spinal cord injury (SCI) is the use of mechanical orthoses. These include traditional orthoses, medial linkage orthoses (MLOs) and reciprocating gait orthoses (RGOs). Independence, energy expenditure, gait parameters, system reliability and cosmesis are important factors in orthotic design. The aim of this review was to compare the evidence of existing mechanical orthoses to that of other types regarding these factors.

METHODS

The preferred reporting items for systematic reviews and meta-analyses (PRISMA) method was used by an experience researcher based on selected keywords and their composition and an electronic search was performed in well-known databases.

RESULTS

Twenty articles were selected for final evaluation. Many were case studies, and also had limited and heterogeneous sample sizes with different instruments used for evaluation. The results of the analysis demonstrated that independence and cosmesis are improved when using MLOs, but gait parameters, energy expenditure and stability are all improved when using RGOs.

CONCLUSION

Those mechanical orthoses which have reciprocal motion and congruency between the anatomical and orthotic joints have been shown to provide positive effects on patient lifestyles. However, further improvement is needed to more effectively meet the needs of SCI patients.

IMPLICATIONS FOR REHABILITATION

The most simple and traditional approach to enable standing and walking by people with SCI is use of purely mechanical orthoses. The most important factors that increase rejection rates of orthoses in paraplegia patients are excessive energy expenditure and increased applied force on upper limb joints. Improvement of the structure of mechanical orthoses is needed to improve independence, energy expenditure, and gait parameters, and is an important approach to improve ambulatory function in subjects with paraplegia.

Enhancing stance phase propulsion during level walking by combining FES with a powered exoskeleton for persons with paraplegia

This paper describes the design and implementation of a cooperative controller that combines functional electrical stimulation (FES) with a powered lower limb exoskeleton to provide enhanced hip extension during the stance phase of walking in persons with paraplegia. The controller utilizes two sources of actuation: the electric motors of the powered exoskeleton and the user's machine (FSM), a set of FES. It consists of a finite-state machine (FSM), a set of proportional-derivative (PD) controllers for the exoskeleton and a cycle-to-cycle adaptive controller for muscle stimulation. Level ground walking is conducted on a single subject with complete T10 paraplegia. Results show a 34% reduction in electrical power requirements at the hip joints during the stance phase of the gait cycle with the cooperative controller compared to using electric motors alone.

Effect of powered gait orthosis on walking in individuals with paraplegia

BACKGROUND

The important purpose of a powered gait orthosis is to provide active joint movement for patients with spinal cord injury.

OBJECTIVES

The aim of this study was to clarify the effect of a powered gait orthosis on the kinematics and temporal-spatial parameters in paraplegics with spinal cord injury.

STUDY DESIGN

Quasi-experimental.

METHODS

Four spinal cord injury individuals experienced gait training with a powered gait orthosis for a minimum of 6 weeks prior to participating in the following walking trials: walking with an isocentric reciprocating gait orthosis and walking with both separate and synchronized movements with actuated orthotic hip and knee joints in a powered gait orthosis. Specific parameters were calculated and compared for each of the test conditions.

RESULTS

Using separate and synchronized actuated movement of the hip and knee joints in the powered gait orthosis increased gait speed and step length and reduced lateral and vertical compensatory motions when compared to the isocentric reciprocating gait orthosis, but there were no significant differences in these parameters. Using the new powered gait orthosis improved knee and hip joint kinematics.

CONCLUSIONS

The powered gait orthosis increased speed and step length as well as hip and knee joint kinematics and reduced the vertical and lateral compensatory motions compared to an isocentric reciprocating gait orthosis in spinal cord injury patients.

CLINICAL RELEVANCE

This new powered gait orthosis has the potential to improve hip and knee joint kinematics, the temporal-spatial parameters of gait in spinal cord injury patients walking.

Performance evaluation of a lower limb exoskeleton for stair ascent and descent with paraplegia

This paper describes the application of a powered lower limb exoskeleton to aid paraplegic individuals in stair ascent and descent. A brief description of the exoskeleton hardware is provided along with an explanation of the control methodology implemented to allow stair ascent and descent. Tests were performed with a paraplegic individual (T10 complete injury level) and data is presented from multiple trials, including the hip and knee joint torque and power required to perform this functionality. Joint torque and power requirements are summarized, including peak hip and knee joint torque requirements of 0.75 Nm/kg and 0.87 Nm/kg, respectively, and peak hip and knee joint power requirements of approximately 0.65 W/kg and 0.85 W/kg, respectively.

A preliminary assessment of legged mobility provided by a lower limb exoskeleton for persons with paraplegia

This paper presents an assessment of a lower limb exoskeleton for providing legged mobility to people with paraplegia. In particular, the paper presents a single-subject case study comparing legged locomotion using the exoskeleton to locomotion using knee-ankle-foot orthoses (KAFOs) on a subject with a T10 motor and sensory complete injury. The assessment utilizes three assessment instruments to characterize legged mobility, which are the timed up-and-go test, the Ten-Meter Walk Test (10 MWT), and the Six-Minute Walk Test (6 MWT), which collectively assess the subject's ability to stand, walk, turn, and sit. The exertion associated with each assessment instrument was assessed using the Physiological Cost Index. Results indicate that the subject was able to perform the respective assessment instruments 25%, 70%, and 80% faster with the exoskeleton relative to the KAFOs for the timed up-and-go test, the 10 MWT, and the 6 MWT, respectively. Measurements of exertion indicate that the exoskeleton requires 1.6, 5.2, and 3.2 times less exertion than the KAFOs for each respective assessment instrument. The results indicate that the enhancement in speed and reduction in exertion are more significant during walking than during gait transitions.

Performance of spinal cord injury individuals while standing with the Mohammad Taghi Karimi reciprocal gait orthosis (MTK-RGO)

Most patients with spinal cord injury use a wheelchair to transfer from place to place, however they need to stand and walk with orthosis to improve their health status. Although many orthoses have been designed for paraplegic patients, they have experienced various problems while in use. A new type of reciprocal gait orthosis was designed in the Bioengineering Unit of Strathclyde University to solve the problems of the available orthoses. Since there was no research undertaken regarding testing of the new orthosis on paraplegic subjects, this study was aimed to evaluate the new orthosis during standing of paraplegic subjects. Five paraplegic patients with lesion level between T12 and L1 and aged matched normal subjects were recruited into this study. The stability of subjects was evaluated during quiet standing and while undertaking hand tasks during standing with the new orthosis and the knee ankle foot orthosis (KAFO). The difference between the performances of paraplegic subjects while standing with both orthoses, and between the function of normal and paraplegic subjects were compared using the paired t test and independent sample t test, respectively. The stability of paraplegic subjects in standing with the new orthosis was better than that of the KAFO orthosis (p < 0.05). Moreover, the force applied on the crutch differed between the orthoses. The functional performance of paraplegic subjects was better with the new orthosis compared with normal subjects. The performance of paraplegic subjects while standing with the new orthosis was better than the KAFO. Therefore, the new orthosis may be useful to improve standing and walking in patients with paraplegia.

Reciprocal gait orthoses and powered gait orthoses for walking by spinal cord injury patients

BACKGROUND

Using mechanical orthoses have some limitations for walking in paraplegic patients. The development of powered orthoses could potentially overcome some of the limitations of those currently available.

OBJECTIVES

The aim of this review was to compare the evidence of the effect of powered gait orthoses (PGOs) when compared to reciprocating gait orthoses (RGOs) and also hip guidance orthoses (HGOs) in improving gait parameters and the energy efficiency of walking by spinal cord injury (SCI) patients.

STUDY DESIGN

Literature review.

METHODS

Using the PRISMA method, and based on selected keywords and their composition, a search was performed in PubMed, Science Direct, and ISI Web of Knowledge databases. Eight articles were selected for final evaluation.

RESULTS

The results of the analysis demonstrated that there is lack of evidence to show that currently-developed powered orthoses improve the walking parameters of SCI patients when compared to RGOs and HGOs.

CONCLUSIONS

The changes offered by PGOs are not substantial enough for such orthoses to be currently considered preferable by SCI subjects for ambulatory purposes. Clinical relevance The development of powered orthoses is still in its infancy and progress needs to be made to improve their functionality and performance envelopes.

Studying the effect of kinematical pattern on the mechanical performance of paraplegic gait with reciprocating orthosis

Paraplegic users of mechanical walking orthoses, e.g. advanced reciprocating gait orthosis (ARGO), often face high energy expenditure and extreme upper body loading during locomotion. We studied the effect of kinematical pattern on the mechanical performance of paraplegic locomotion, in search for an improved gait pattern that leads to lower muscular efforts. A three-dimensional, four segment, six-degrees-of-freedom skeletal model of the advanced reciprocating gait orthosis-assisted paraplegic locomotion was developed based on the data acquired from an experimental study on a single subject. The effect of muscles was represented by ideal joint torque generators. A response surface analysis was performed on the model to determine the impact of the kinematical parameters on the resulting muscular efforts, characterized by net joint torques. Results indicated that a lateral bending manoeuvre at the trunk would facilitate the foot clearance by reducing the torque requirement of the whole body lateral tilting. For swing leg advancement, the trunk posterior bending manoeuvre was found to be more effective and efficient than the whole body axial rotation, owing to the coupled reciprocal action of the advanced reciprocating gait orthosis. It was hypothesized that a modified gait pattern, with larger trunk movements and no axial rotation, could improve the energy expenditure and upper body loading during advanced reciprocating gait orthosis-assisted locomotion. More detailed modelling and experimental studies are needed to verify this hypothesis and evaluate its potential effects on the soft tissue strains.

A Method for the Autonomous Control of Lower Limb Exo-skeletons for Persons with Paraplegia

Efforts have recently been reported by several research groups on the development of computer-controlled lower limb orthoses to enable legged locomotion in persons with paraplegia. Such systems must employ a control framework that provides essential movements to the paraplegic user (i.e., sitting, standing, and walking), and ideally enable the user to autonomously command these various movements in a safe, reliable, and intuitive manner. This paper describes a control method that enables a paraplegic user to perform sitting, standing, and walking movements, which are commanded based on postural information measured by the device. The proposed user interface and control structure was implemented on a powered lower limb orthosis, and the system was tested on a paraplegic subject with a T10 complete injury. Experimental data is presented that indicates the ability of the proposed control architecture to provide appropriate user-initiated control of sitting, standing, and walking. The authors also provide a link to a video that qualitatively demonstrates the user's ability to independently control basic movements via the proposed control method.

Control and implementation of a powered lower limb orthosis to aid walking in paraplegic individuals

This paper describes a powered lower-limb orthosis that is intended to provide gait assistance to spinal cord injured (SCI) individuals by providing assistive torques at both hip and knee joints, along with a user interface and control structure that enables control of the powered orthosis via upper-body influence. The orthosis and control structure was experimentally implemented on a paraplegic subject (T10 complete) in order to provide a preliminary characterization of its capability to provide basic walking. Data and video is presented from these initial trials, which indicates that the orthosis and controller are able to effectively provide walking within parallel bars at an average speed of 0.8 km/hr.

Evaluation of a novel powered gait orthosis for walking by a spinal cord injury patient

BACKGROUND

The aim of this case study was to analyze the effect on gait parameters of a new design of powered gait orthosis which applied synchronized motions to both the hip and knee joints when utilized for walking by a spinal cord injury (SCI) patient.

CASE DESCRIPTION AND METHODS

Two orthoses were evaluated while worn by an incomplete SCI subject. Gait evaluation was performed when walking with an isocentric reciprocating gait orthosis (IRGO) and compared to that demonstrated by a newly developed powered version. This new orthosis was based on the IRGO superstructure but incorporated powered hip and knee joints using electrically motorized actuators.

FINDINGS AND OUTCOMES

These gait parameters were improved when compared to standard IRGO and initial testing with the orthosis with only the hip or the knee joints activated in isolation. Maximum hip flexion and extension angles, as well as the maximum knee flexion and extension angles all increased when walking with the powered RGO compared to the IRGO.

CONCLUSIONS

Gait evaluation of this newly developed orthosis showed improvement in measured parameters when compared to walking with an IRGO. Clinical relevance This case study gave the authors confidence to extend the research to a more extensive study with a group of SCI patients.

The effect of an isocentric reciprocating gait orthosis incorporating an active knee mechanism on the gait of a spinal cord injury patient: a single case study

OBJECTIVE

The aim of this study was to identify the effect of induced knee flexion during gait on the kinematics and temporal-spatial parameters during walking by a patient with spinal cord injury (SCI) through the application of an isocentric reciprocating gait orthosis (IRGO) with a powered knee mechanism.

METHODS

Two orthoses were considered and evaluated for an ISCI subject with a T8 level of injury. An IRGO was initially manufactured by incorporating drop lock knee joints and was fabricated with custom molded AFOs to block ankle motion. This orthosis was also adapted with electrically-activated knee joints to provide active knee extension and flexion when disengaged.

RESULTS

Walking speed, stride length and cadence were increased 37.5%, 11% and 26%, respectively with the new orthosis as compared to using the IRGO. The vertical and horizontal compensatory motions reduced compared to mechanical IRGO. At end of stance phase, knee joint flexion was 37.5° for the AKIRGO compared to 7° of movement when walking with the IRGO. The overall pattern of walking produced was comparable to that of normal human walking.

CONCLUSION

Knee flexion during swing phase resulted in an improved gait performance and also reduction in compensatory motions when compared to a mechanical IRGO.

Evaluation of a novel powered hip orthosis for walking by a spinal cord injury patient: a single case study

BACKGROUND

The aim of this case study was to identify the effect of a powered hip orthosis on the kinematics and temporal-spatial parameters of walking by a patient with spinal cord injury (SCI).

CASE DESCRIPTION AND METHODS

Two orthoses were evaluated while worn by an incomplete SCI subject with a T-8level of injury. Gait evaluation was performed when walking with an Isocentric Reciprocating Gait Orthosis (IRGO) and compared to that demonstrated by a newly powered version of the orthosis; based on the IRGO superstructure but incorporating powered hip joints using an electrically motorized actuator that produced active hip joint extension and flexion.

FINDINGS AND OUTCOMES

The powered hip orthosis, when compared to the IRGO, increased the speed of walking, the step length and also the cadence demonstrated by this subject. Vertical and horizontal compensatory motions with new orthosis decreased. Hip angles when walking with this orthosis were comparative to those demonstrated by normal walking patterns.

CONCLUSIONS

The hip actuator produced positive effects on the kinematics and temporal-spatial parameters of gait during level-ground walking trials, resulting in an alternative approach to walking by SCI patients.

Design and simulation of a new powered gait orthosis for paraplegic patients

BACKGROUND AND AIM

This article describes the development and testing of a new powered gait orthosis to potentially assist spinal cord injury patients to walk by producing synchronized hip and knee joint movements.

TECHNIQUE

The first evaluation of the orthosis was performed without users, and was followed by evaluation of the orthosis performance using three healthy subjects to test the structure under weight-bearing conditions. The orthosis was primarily evaluated to ascertain its ability to generate appropriate hip and knee motion during walking. The walking experiments replicated the flexion and extension of both the hip and knee produced by the actuators which had previously been demonstrated during the initial computer simulations.

DISCUSSION

The results suggest that this new orthosis could be used to assist paraplegic subjects who have adequate ranges of motion and also with weakness or reduced tone to ambulate, and may also be suitable for other subjects with impaired lower limb function (e.g. stroke, poliomyelitis, myelomeningocele and traumatic brain injury provided they do not have increased tone or movement disorders.

Preliminary evaluation of a powered lower limb orthosis to aid walking in paraplegic individuals

This paper describes a powered lower-limb orthosis that is intended to provide gait assistance to spinal cord injured (SCI) individuals by providing assistive torques at both hip and knee joints. The orthosis has a mass of 12 kg and is capable of providing maximum joint torques of 40 Nm with hip and knee joint ranges of motion from 105° flexion to 30° extension and 105° flexion to 10° hyperextension, respectively. A custom distributed embedded system controls the orthosis with power being provided by a lithium polymer battery which provides power for one hour of continuous walking. In order to demonstrate the ability of the orthosis to assist walking, the orthosis was experimentally implemented on a paraplegic subject with a T10 complete injury. Data collected during walking indicates a high degree of step-to-step repeatability of hip and knee trajectories (as enforced by the orthosis) and an average walking speed of 0.8 km/hr. The electrical power required at each hip and knee joint during gait was approximately 25 and 27 W, respectively, contributing to the 117 W overall electrical power required by the device during walking. A video of walking corresponding to the aforementioned data is included in the supplemental material.

A Powered Lower Limb Orthosis for Providing Legged Mobility in Paraplegic Individuals

This paper presents preliminary results on the development of a powered lower limb orthosis intended to provide legged mobility (with the use of a stability aid, such as forearm crutches) to paraplegic individuals. The orthosis contains electric motors at both hip and both knee joints, which in conjunction with ankle-foot orthoses, provides appropriate joint kinematics for legged locomotion. The paper describes the orthosis and the nature of the controller that enables the SCI patient to command the device, and presents data from preliminary trials that indicate the efficacy of the orthosis and controller in providing legged mobility.

Recovery of control of posture and locomotion after a spinal cord injury: solutions staring us in the face

Over the past 20 years, tremendous advances have been made in the field of spinal cord injury research. Yet, consumed with individual pieces of the puzzle, we have failed as a community to grasp the magnitude of the sum of our findings. Our current knowledge should allow us to improve the lives of patients suffering from spinal cord injury. Advances in multiple areas have provided tools for pursuing effective combination of strategies for recovering stepping and standing after a severe spinal cord injury. Muscle physiology research has provided insight into how to maintain functional muscle properties after a spinal cord injury. Understanding the role of the spinal networks in processing sensory information that is important for the generation of motor functions has focused research on developing treatments that sharpen the sensitivity of the locomotor circuitry and that carefully manage the presentation of proprioceptive and cutaneous stimuli to favor recovery. Pharmacological facilitation or inhibition of neurotransmitter systems, spinal cord stimulation, and rehabilitative motor training, which all function by modulating the physiological state of the spinal circuitry, have emerged as promising approaches. Early technological developments, such as robotic training systems and high-density electrode arrays for stimulating the spinal cord, can significantly enhance the precision and minimize the invasiveness of treatment after an injury. Strategies that seek out the complementary effects of combination treatments and that efficiently integrate relevant technical advances in bioengineering represent an untapped potential and are likely to have an immediate impact. Herein, we review key findings in each of these areas of research and present a unified vision for moving forward. Much work remains, but we already have the capability, and more importantly, the responsibility, to help spinal cord injury patients now.