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

Design and Preliminary Validation of a Lightweight Powered Exoskeleton During Level Walking for Persons With Paraplegia

Upright-legged locomotion is a desirable ability for people with paraplegia. This paper introduces a newly developed lightweight powered exoskeleton (LIPE) for level walking and posture transfer of people with paraplegia using a user-centered design concept, which integrates the requirements of practical use, mechanical structure, and control system. The LIPE was evaluated with two subjects through several experimental tasks including kinematics and dynamics analysis in a local hospital. Results of functional evaluation showed that these subjects received the exoskeleton intervention well and the LIPE could provide appropriate gait assistance to the wearer during level walking, it could also help the wearer achieve the posture transfer from sitting to standing or from standing to sitting independently. Moreover, an endurance test also indicated that LIPE allows wearers to use it continuously for a long time. It is lightweight, cost effective, easy to use, and practical for people with paraplegia in their daily lives.

Systematic review on wearable lower-limb exoskeletons for gait training in neuromuscular impairments

Gait disorders can reduce the quality of life for people with neuromuscular impairments. Therefore, walking recovery is one of the main priorities for counteracting sedentary lifestyle, reducing secondary health conditions and restoring legged mobility. At present, wearable powered lower-limb exoskeletons are emerging as a revolutionary technology for robotic gait rehabilitation. This systematic review provides a comprehensive overview on wearable lower-limb exoskeletons for people with neuromuscular impairments, addressing the following three questions: (1) what is the current technological status of wearable lower-limb exoskeletons for gait rehabilitation?, (2) what is the methodology used in the clinical validations of wearable lower-limb exoskeletons?, and (3) what are the benefits and current evidence on clinical efficacy of wearable lower-limb exoskeletons? We analyzed 87 clinical studies focusing on both device technology (e.g., actuators, sensors, structure) and clinical aspects (e.g., training protocol, outcome measures, patient impairments), and make available the database with all the compiled information. The results of the literature survey reveal that wearable exoskeletons have potential for a number of applications including early rehabilitation, promoting physical exercise, and carrying out daily living activities both at home and the community. Likewise, wearable exoskeletons may improve mobility and independence in non-ambulatory people, and may reduce secondary health conditions related to sedentariness, with all the advantages that this entails. However, the use of this technology is still limited by heavy and bulky devices, which require supervision and the use of walking aids. In addition, evidence supporting their benefits is still limited to short-intervention trials with few participants and diversity among their clinical protocols. Wearable lower-limb exoskeletons for gait rehabilitation are still in their early stages of development and randomized control trials are needed to demonstrate their clinical efficacy.

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.

Joint trajectory generator for powered orthosis based on gait modelling using PCA and FFT

In this work, we propose a method able to find user-oriented gait trajectories that can be used in powered lower limb orthosis applications. Most research related to active orthotic devices focuses on solving hardware issues. However, the problem of generating a set of joint trajectories that are user-oriented still persists. The proposed method uses principal component analysis to extract shared features from a gait dataset, taking into consideration gait-related variables such as joint angle information and the user's anthropometric features, used directly in an orthosis application. The trajectories of joint angles used by the model are represented by a given number of harmonics according to their respective Fourier series analyses. This representation allows better performance of the model, whose capability to generate gait information is validated through experiments using a real active orthotic device, analysing both joint motor energy consumption and user metabolic effort.

The influence of new medial linkage orthosis on walking and independence in spinal cord injury patients: a pilot study

In an effort to overcome the disadvantages of reciprocating gait orthoses (RGOs) and medial linkage orthoses (MLOs), a new design of MLO was developed. Therefore the aim of this study was comparison effect of a new reciprocating MLO and traditional isocentric RGO on gait parameters and functional independence (orthosis donning and doffing time) in spinal cord injury (SCI) subjects to provide more evidence of its efficacy. Four people with motor incomplete SCI participated in this study. Each participant was fitted with an MLO and isocentric reciprocating gait orthosis (IRGO) to enable a comparison of walking speed, cadence and endurance to be performed. There were no statistically significant differences demonstrated in temporal-spatial parameters between the orthotic walking conditions in this study, but walking with the MLO improved the stride length and speed of walking by 28.57 and 40.9% compared with walking with an IRGO as a control condition. Hip flexion occurred predominantly during single-support phases, with negligible motion during double-support phases. The first and second Subjects had hip kinematic pattern more near normal when they walked with medial linkage reciprocal gait orthosis (MLRGO) in comparison with IRGO. There was significant difference between donning and doffing in two conditions (P=0.046) but there was not significant difference between two conditions in standing and sitting although these two conditions improved by new MLO. The new MLO provided a quicker and more independent gait compared with IRGO, in addition the new MLO made it easier for subjects to get from sitting to standing and from standing to sitting.

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.

Comparison of gait between healthy participants and persons with spinal cord injury when using the advanced reciprocating gait orthosis

BACKGROUND

The advanced reciprocating gait orthosis (ARGO) has a rigid structure which provides restricted movement at the hip, knee, and ankle joints and incorporates a pelvic section with an extended section in the lumbar region. Healthy subjects, when walking with an RGO in situ, could feasibly demonstrate the level of limitation in movement imposed by ARGO-assisted ambulation.

OBJECTIVE

The aim of this study was to compare the function of the advanced reciprocating gait orthosis when fitted with the dorsiflexion-assist ankle-foot orthoses on temporal-spatial parameters and kinematics of walking in both able-bodied people and those with spinal cord injury.

STUDY DESIGN

Quasi experimental design.

METHODS

Data were acquired from six able-bodied and four spinal cord injury subjects who used an advanced reciprocating gait orthosis which incorporated dorsiflexion-assist ankle-foot orthoses. Kinematics and temporal-spatial parameters were calculated and compared.

RESULTS

All able-bodied individuals walked with speeds which were only approximately one-third that of when walking without an orthosis. The mean step length and cadence were both reduced by 48% and 6%, respectively. There were significant differences in hip, knee, and ankle joint range of motions between normal walking and walking with the advanced reciprocating gait orthosis both in able-bodied subjects and patients with spinal cord injury. There were also significant differences in the speed of walking, cadence, step length, hip range of motion, and ankle range of motion when using the advanced reciprocating gait orthosis between the two groups.

CONCLUSION

Temporal-spatial parameters and lower limb sagittal plane kinematics of walking were altered compared to normal walking, especially when spinal cord injury subjects walked with the advanced reciprocating gait orthosis compared to the able-bodied subjects.

CLINICAL RELEVANCE

To produce an improvement in RGO function, an increase in walking performance should involve attention to improvement of hip, knee, and ankle joint kinematics, which differs significantly from normal walking.

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.

The effect of ankle joint mobility when using an isocentric reciprocating gait orthosis (IRGO) on energy consumption in people with spinal cord injury: preliminary results

OBJECTIVES

The aim of this study was to evaluate the effect of walking with isocentric reciprocating gait orthoses (IRGOs) utilizing two designs of ankle foot orthoses (AFOs) on specific outcome measures in people with spinal cord injury (SCI).

METHODS

Four volunteer SCI subjects participated in this study, and were fitted with an IRGO equipped with either solid or dorsiflexion-assisted AFOs in a randomized order. Subjects walked at their self-selected speed along a flat walkway to enable a comparison of walking speed, endurance and the resulting physiological cost index (PCI) to be performed.

RESULTS

Increased walking speed, increased distance walked and less PCI were demonstrated in walking with the IRGO incorporating dorsiflexion-assisted AFOs as compared to walking with an IRGO plus solid AFO as a control condition.

CONCLUSION

This study demonstrated that people with SCI could walk at relatively higher speeds and with greater endurance and a reduced PCI when utilizing an IRGO with dorsiflexion-assisted AFO components compared to solid ones. It is therefore concluded that the IRGO incorporating dorsiflexion-assisted AFOs may be an effective alternative in helping to reduce the energy consumption experienced by people with SCI.

The influence of orthotic gait training with an isocentric reciprocating gait orthosis on the walking ability of paraplegic patients: a pilot study

OBJECTIVES

The aim of this study was to evaluate the influence of walking with an isocentric reciprocating gait orthosis (IRGO) by spinal cord injury (SCI) patients on walking speed, distance walked and energy consumption whilst participating in a 12-week gait re-training program.

METHODS

Six people with motor complete SCI (mean age 29 years, weight 63 kg and height 160 cm with injury levels ranging from T8 to T12) participated in this study. Gait evaluation was performed at baseline and after 4, 8 and 12 weeks. Walking speed and heart rate were measured to calculate the resulting physiological cost index (PCI).

RESULTS

Reductions in energy consumption were observed after 4, 8 and 12 weeks compared with baseline but were not significant. However, walking distance increased significantly (P=0.010, P=0.003 and P=0.005, respectively) and also did so during the 8-12-week period (P=0.013). Walking speed also improved, but not significantly.

CONCLUSION

Intensive gait training with the IRGO improved walking speed and the distance walked by paraplegics, as well as reducing the PCI of walking, as compared with baseline during the whole 12-week period. This indicates that further improvements in these parameters may be expected when utilizing gait training longer than 8 weeks.

The efficacy of powered orthoses on walking in persons with paraplegia

BACKGROUND

Powered orthoses are a new generation of assistive devices for people with spinal cord injury, which are designed to induce motion to paralyzed lower limb joints using external power via electric motors or pneumatic or hydraulic actuators.

OBJECTIVE

Powered gait orthoses provide activated movement of lower limb joints to limit the forces applied through the upper limb joints and trunk muscles during ambulation due to the need to use an external walking aid, while simultaneously improving the kinetics and kinematics of walking in subjects with spinal cord injury. This article reviews their walking efficacy when used by people with paraplegia.

STUDY DESIGN

Literature review.

METHOD

A literature search was performed in ISI Web of Knowledge, PubMed, Google Scholar, ScienceDirect, and Scopus databases.

RESULTS

Efficacy was demonstrated in producing activated motion of lower limb joints. Powered gait orthoses have a beneficial effect on the kinetics, kinematics, and temporal-spatial parameters of gait, but their effect on muscle activity in individuals with spinal cord injury is still unclear.

CONCLUSIONS

Further research is needed regarding the design and construction of powered gait orthoses using significant power application to the ankle joints and their effect on lower limb muscle activity and gait patterns in spinal cord injury subjects.

CLINICAL RELEVANCE

Powered orthoses is a new generation of orthotic intervention that could potentially be significant in assisting in improving the walking parameters and energy consumption of spinal cord injury subjects.

Design and analysis of a new medial reciprocal linkage using a lower limb paralysis simulator

STUDY DESIGN

A feasibility study on the effect of a new reciprocating orthosis on specific gait parameters for use by people with spinal cord injury.

OBJECTIVES

The aim of this study was to design and develop a new medial linkage orthosis (MLO) mechanism incorporating a reciprocating motion and to determine its efficacy in improving specific spatiotemporal, kinematic and kinetic parameters while ambulating when worn by healthy subjects. This was achieved via the use of a lower limb paralysis simulator (LLPS).

METHODS

A reciprocating joint with a remote center of motion was designed for use as an MLO. A prototype was fabricated and incorporated into an orthosis and equipped with a saddle to make the reciprocating motion possible. The efficacy of the orthosis was evaluated on four able-bodied healthy subjects who were trained to walk with the MLO attached to the LLPS.

RESULTS

Mean walking speed, stride length, stride time and cadence was 0.09±0.007 m s(-1), 0.42±0.01 m, 4.89±0.45 s and 29.54±4.32 steps min(-1), respectively, when healthy subjects walked with the new orthosis. The mean hip joint torque produced was 0.36±0.13 Nm.

CONCLUSION

In this study a new MLO was designed and fabricated that provided a reciprocating mechanism using a four-bar mechanism to set the virtual axis of the mechanism in a more proximal position than hinge-type joints. Further investigation is currently underway to assess its effect on gait parameters and energy expenditure in paraplegic patients.

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.

Gait evaluation of new powered knee-ankle-foot orthosis in able-bodied persons: a pilot study

BACKGROUND

Knee-ankle-foot orthoses are utilized for walking by patients with lower limb weakness. However, they may be rejected by patients due to the lack of knee flexion available when using them for walking activities.

AIM

The aim of this study was to perform a pilot study investigating the effect of a new powered knee-ankle-foot orthosis on walking in healthy persons before testing with patients with lower limb weakness.

METHODS

Walking evaluation was performed on five healthy subjects (mean age: 26 ± 5.6 years). Walking trials were randomly performed in three test conditions: normal walking without an orthosis, walking with a conventional knee-ankle-foot orthosis unilaterally, and also with a new powered knee-ankle-foot orthosis applied to the same leg.

RESULTS

The means of walking speed, cadence, and knee flexion during swing and step length were all decreased. Compensatory motions were increased by both orthoses compared to normal walking. More knee flexion was observed in both swing and stance phases when walking with the powered knee-ankle-foot orthosis compared to the conventional knee-ankle-foot orthosis.

CONCLUSION

The results demonstrated the potential of a powered orthosis in providing improvements in gait parameters compared to a conventional device in healthy subjects but are yet untested in subjects with lower limb weakness.

CLINICAL RELEVANCE

The results of this study demonstrated that a powered knee-ankle-foot orthosis could lock the knee during stance and provide active knee flexion during swing to potentially reduce the tripping during ambulation.

Comparison of gait between healthy participants and persons with spinal cord injury when using a powered gait orthosis-a pilot study

OBJECTIVES

The aim of this study was to evaluate the effect of a powered gait orthosis (PGO) on the temporal-spatial parameters and kinematics of walking in both healthy participants and persons with spinal cord injury (SCI) using three-dimensional motion analysis to facilitate further development of such devices.

METHODS

Kinematics and temporal spatial data were obtained from three healthy participants and four persons with SCI who walked using the same design of PGO.

RESULTS

Walking speed was reduced by 28% and step length by 29% in healthy individuals when walking with PGO compared with normal walking and that recorded for persons with SCI was approximately one-third that of normal walking. There were significant differences in hip and knee joint ranges of motion in comparison between walking with PGO in healthy participants and walking with PGO in persons with SCI.

CONCLUSION

Walking with a PGO by healthy participants significantly reduced critical gait parameters, and further development work is needed to produce a more effective device to match closely the gait parameters of normal walking by healthy participants. Significant differences between normal walking and that evidenced with the PGO by both healthy participants and persons with SCI were detected.

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.

The physiological cost index of walking with mechanical and powered gait orthosis in patients with spinal cord injury

OBJECTIVES

Mechanical orthoses, such as the hip knee ankle foot orthosis (HKAFO) and the isocentric reciprocating gait orthosis (IRGO), are both used for walking in spinal cord injury (SCI) patients. The aim of this study was to analyze the energy expenditure during walking with these orthoses compared with a powered gait orthosis (PGO) in patients with SCI.

METHODS

Five patients with SCI who were experienced users of HKAFOs participated in this study. Subjects were also fitted with an IRGO and PGO and underwent a specific gait training program. Patients walked along a flat walkway using the three types of orthosis at their self-selected walking speed. A stop watch and a polar heart rate monitor were used to measure the speed of walking and heart rate.

RESULTS

Walking speed, the distance walked and the physiological cost index (PCI) all improved with both the new PGO and the IRGO as compared with the HKAFO.

CONCLUSIONS

A PGO can improve walking speed and the distance walked and reduce the PCI of walking as compared with mechanical orthoses, probably due to the activated movements of the lower limb joints.