Effects of joint motion constraints on the gait of normal subjects and their implications on the further development of hybrid FES orthosis for paraplegic persons

Walking ability of spinal cord injury individuals: How to improve it?

BACKGROUND

Subjects with Spinal Cord Injury (SCI) should use various assistive devices to stand and walk. Unfortunately they suffer from slow walking speed, high energy consumption, and too much force applied on upper limb while walking. The aim of this study was to determine the gap between the gait performance of SCI and normal subjects to conclude how the performance of SCI can be improved.

METHOD

Three groups of SCI walked with orthosis, SCI walked without orthosis, and normal subjects were recruited in this study. The normal subjects also walked with the same orthoses as SCI subjects. Some parameters such as ranges of motion of hip, knee and spatiotemporal gait parameters were evaluated by use of Qualysis motion analysis system. The difference between the gait parameters of three groups were evaluated by use of two sample t test.

RESULTS

The mean values of hip joint range of motion of normal subjects while walking with and without orthosis were 48.3 ± 2.5 and 18.5 ± 8.8 degrees, respectively (p-value = 0.00). There was a significant difference between walking speed of normal subjects with and without orthosis. The walking speed of SCI subject with and without orthosis differed significantly.

CONCLUSION

Although use of orthosis enable SCI subjects to stand and walk, but has some restrictions. As use of orthosis decreased the abilities of normal subjects it can be concluded that more attention should be done on design of orthosis and style of 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.

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).

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.

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.

Functional walking ability of paraplegic patients: comparison of functional electrical stimulation versus mechanical orthoses

BACKGROUND

Spinal cord injury (SCI) can cause partial or complete paralysis of the lower extremities, impairing the ability of individuals to stand and walk. Various types of mechanical orthoses, functional electrical stimulation (FES) systems and hybrid orthoses that incorporate FES have been designed to restore the ability of individuals with SCI to stand and walk. Standing and ambulation performance of SCI subjects using these different systems have been previously evaluated using energy consumption analysis, stability analysis and by quantitative gait analysis. Though FES-based systems are technologically more complex than passive mechanical systems, it is not apparent whether user performance is substantially improved with FES and hybrid orthoses compared to purely mechanical orthoses.

METHOD

An electronic search was performed via the Pubmed, Embase and ISI Web of Knowledge data base from 1960 to 2010. The abstracts, titles and full details of each individual study were assessed by the authors. The findings that were indicative of users' performance with the FES systems and hybrid systems were compared with that of mechanical orthoses. Moreover, the effects of using these different systems on physiological health were evaluated.

RESULTS

Twelve original articles and 5 review articles were selected by the author. However, most of the original articles were case studies. The results of previous investigations indicate that user performance with the mechanical orthoses was generally better than that of the hybrid and FES systems based on subject's stability and energy consumption while walking. Moreover, subject reportedly experienced a higher incidence of problems with the use of hybrid orthoses and FES systems compared with mechanical orthoses.

CONCLUSION

FES and hybrid orthoses offer considerable potential for restoring standing and walking abilities in persons with SCI. However, improvements in their designs and operation with subsequent objective evaluations are required to demonstrate that these systems enable users to improve their performance over that currently possible with passive, mechanical orthoses.

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.

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.

Gait evaluation of a novel hip constraint orthosis with implication for walking in paraplegia

The aim of this study was to determine the effects of a newly developed reciprocal gait orthosis (RGO) with a variable constraint hip mechanism (VCHM) on the kinematics and kinetics of normal gait. The VCHM was compared with the isocentric reciprocating gait orthosis (IRGO) for walking after paraplegia. Both the VCHM and the IRGO were evaluated with able-bodied volunteers with the hip reciprocating mechanisms coupled and uncoupled. The VCHM was further evaluated with context-dependent coupling based on a finite-state control algorithm utilizing information from brace-mounted sensors. Walking performance for each brace condition was also compared to normal walking without an orthosis. Without the hip controller, the VCHM affected the kinematics of the hip joint in a similar manner as the IRGO, regardless of whether the hip reciprocator was coupled or uncoupled. With the controller active, hip kinematics with the VCHM were closer to normal gait than with the IRGO or any other condition tested (Intraclass correlation coefficient, ICC=0.96). The effects of the braces on the knee and ankle angles were not as prominent as their effects on the hip angles. In terms of kinetics, the VCHM with controller active allowed the generation of joint moments that were closer to normal (ICC=0.80) than the IRGO with hips coupled (ICC= 0.68). There was no statistically significant difference between the various conditions tested in terms of step-length and no statistically significant difference in the preferred walking speed between the IRGO and normal walking, whether or not the hips were coupled. However, there was a 25% reduction in walking speed with the VCHM when compared to normal, and the relative magnitudes of the EMG activity of three muscles (tibialis anterior, quadriceps, and hamstrings) were also higher with the VCHM than with either the IRGO or normal gait, likely due to the additional weight of the mechanism. Overall, the VCHM with controller active provided smooth control of the hip joints via context-dependent coupling and allowed for increased hip flexion relative to the IRGO. The results suggest that the VCHM with controlled joint coupling may eventually be a valuable component of a hybrid system combining functional electrical stimulation (FES) with orthotics.

The influence of test conditions on characterization of the mechanical properties of brain tissue

To understand brain injuries better, the mechanical properties of brain tissue have been studied for 50 years; however, no universally accepted data set exists. The variation in material properties reported may be caused by differences in testing methods and protocols used. An overview of studies on the mechanical properties of brain tissue is given, focusing on testing methods. Moreover, the influence of important test conditions, such as temperature, anisotropy, and precompression was experimentally determined for shear deformation. The results measured at room temperature show a stiffer response than those measured at body temperature. By applying the time-temperature superposition, a horizontal shift factor a(T)=8.5-11 was found, which is in agreement with the values found in literature. Anisotropy of samples from the corona radiata was investigated by measuring the shear resistance for different directions in the sagittal, the coronal, and the transverse plane. The results measured in the coronal and the transverse plane were 1.3 and 1.25 times stiffer than the results obtained from the sagittal plane. The variation caused by anisotropy within the same plane of individual samples was found to range from 25% to 54%. The effect of precompression on shear results was investigated and was found to stiffen the sample response. Combinations of these and other factors (postmortem time, donor age, donor type, etc.) lead to large differences among different studies, depending on the different test conditions.

Wavelet analysis of head acceleration response under dirac excitation for early oedema detection

The present work deals with the application of an innovative in-house developed wavelet-based methodology for the analysis of the acceleration responses of a human head complex model as a simulated diffused oedema progresses. The human head complex has been modeled as a structure consisting of three confocal prolate spheroids, whereas the three defined regions by the system of spheroids, from the outside to the inside, represent the scull, the region of cerebrospinal fluid, and the brain tissue. A Dirac-like pulse has been used to excite the human head complex model and the acceleration response of the system has been calculated and analyzed via the wavelet-based methodology. For the purpose of the present analysis, a wave propagation commercial finite element code, LS-DYNA 3D, has been used. The progressive diffused oedema was modeled via consecutive increases in brain volume accompanied by a decrease in brain density. It was shown that even a small increase in brain volume (at the level of 0.5%) can be identified by the effect it has on the vibration characteristics of the human head complex. More precisely, it was found that for some of the wavelet decomposition levels, the energy content changes monotonically as the brain volume increases, thus providing a useful index of monitoring an oncoming brain oedema before any brain damage appears due to uncontrolled intracranial hypertension. For the purpose of the present work and for the levels of brain volume increase considered in the present analysis, no pressure increase was assumed into the cranial vault and, associatively, no brain compliance variation.

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

A number of orthoses have been developed to restore stance and walking in paraplegic subjects. Compliance, however, has been limited, mainly owing to walking effort. Use of the forces produced by actuators is an effective way to solve the problem of the considerable effort required for orthotic gait, namely high muscular effort and high energy expenditure. The purpose of the present study was to investigate the effects of assistance by external actuators on the orthotic gait of spinal cord injury (SCI) patients. Two kinds of linear actuator were developed by using direct current (d.c.) motors for assisting the knee and hip joint of a gait orthosis. They were mounted on the knee and hip joint of a commercial advanced reciprocating gait orthosis (ARGO), and a new two-degree-of-freedom externally powered gait orthosis was thus developed. The orthosis was assessed through inter-subject experiments on five male adult complete SCI patients. Owing to the short training period available for the assisted gait, simultaneous operation of both joint actuators was not conducted: either the knee actuation or the hip actuation was executed only. Thus, the knee actuator and the hip actuator were assessed with a T12 subject and with subjects for T5, T8, T11, and T12 respectively. The motions of the gaits, assisted by the linear actuators, were measured by a Vicon 370 system, and the general gait parameters and compensatory motions were evaluated. Results demonstrated that (a) all subjects could walk without falling, assisted either by the knee or the hip actuator; (b) both the knee and hip joint actuator increased the gait speed and the step length; (c) the knee flexion produced by the orthosis improved the dynamic cosmesis of walking; and (d) lateral compensatory motions as well as vertical ones tended to decrease when the hip joint was assisted, which could contribute to a reduction in walking effort.

The feasibility of a functional neuromuscular stimulation powered mechanical gait orthosis with coordinated joint locking

The purpose of this study was to examine the feasibility of a hybrid orthosis for walking after spinal cord injury (SCI) that coordinates the locking and unlocking of knee and ankle joints of a reciprocating gait orthosis (RGO), while injecting propulsive forces and controlling unlocked joints with functional neuromuscular stimulation (FNS). The effectiveness of the hybrid system relative to gait stability and posture were determined in this simulation study. A three-dimensional computer model of a hybrid orthosis system (HOS) combining FNS with a RGO incorporating feedback control of muscle activation and coordinated joint locking was developed in Working Model 3D. The simulated hybrid orthosis system achieved gait speeds, stride lengths, and cadences of 0.51 +/- 0.03 m/s, 0.85 +/- 0.04 m, and 72 +/- 4 steps/min respectively, exceeding the performance of other hybrid systems. Forward trunk tilt was found to be necessary during initial step from standing and pro-swing, but posture and stability were significantly improved over FNS-only systems. The results of the model shows that a HOS that coordinates knee and ankle joint locking with electrical stimulation to the paralyzed muscles holds significant advantages over brace- and FNS-only walking systems in terms of enhanced trunk stability and posture.

Simulation of a functional neuromuscular stimulation powered mechanical gait orthosis with coordinated joint locking

The purpose of this study was to examine a hybrid orthosis system (HOS) for walking after spinal-cord injury (SCI) that coordinates the mechanical locking and unlocking of knee and ankle joints of a reciprocating gait orthosis (RGO), while propulsive forces are injected and unlocked joints controlled with functional neuromuscular stimulation (FNS). The likely effectiveness of the HOS in terms of forward progression, stability, and posture of paraplegic gait was determined in this simulation study. A three-dimensional computer model of a HOS combining FNS with an RGO incorporating feedback control of muscle activation and joint locking was developed. An anthropomorphic human model included passive joint moments and a foot-ground contact model adapted from other studies. A model of the RGO reciprocally coupled the hips and locked and unlocked the knee and ankle joints during stance and swing respectively. The actions of muscles under FNS activation were modeled via closed-loop control of joint torque inputs. A walking aid that mimicked canes and voluntary upper extremity actions maintained lateral stability by providing the necessary shoulder forces and moments. The simulated HOS achieved gait speeds of 0.51 +/- 0.03 m/s, stride lengths of 0.85 +/- 0.04 m, and cadences of 72 +/- 4 steps/min, exceeding the reported performance of other assistive gait systems. Although minimal forward trunk tilt was found to be necessary during specific phases of gait, posture, and stability were significantly improved over FNS-only systems.

Obstacle avoidance during human walking: effects of biomechanical constraints on performance11No commercial party having a direct financial interest in the results of the research supporting this article has or will confer a benefit on the author(s) or on any organization with which the author(s) is/are associated

OBJECTIVE

To determine whether fixation of the ankle joint, the knee joint, or both increasingly affects the performance of a newly learned task, that is, stepping over an obstacle.

DESIGN

Randomized trial.

SETTING

Research laboratory of a university hospital in Switzerland.

PARTICIPANTS

Eighteen healthy, young volunteers.

INTERVENTION

Subjects walked on a treadmill and, with reduced vision, stepped with the right leg over a randomly approaching obstacle. They adapted to the task during the 2 runs. In the third run, fixating orthoses of the ankle-foot (AFO), knee (KO), or both (KAFO) were attached to the left leg.

MAIN OUTCOME MEASURE

The "performance" consisted of leg muscle activity, joint movements, swing phase duration, and the clearance between the foot and the obstacle. The changes within runs (adaptation) and between runs (eg, transfer) were evaluated.

RESULTS

The attached orthoses caused a reduced transfer of performance in the KAFO and KO between runs 2 and 3. No differences in the rate of adaptation were observed among the 3 groups during the third run.

CONCLUSIONS

A movement restriction of the supporting leg worsened the performance of the contralateral leg in a locomotor task. Performance was more affected by knee-joint fixation than by ankle-joint fixation alone and, consequently, the need for relearning is greater.

A knee and ankle flexing hybrid orthosis for paraplegic ambulation

Limitations of mechanical walking orthoses for paraplegics are high energy consumption and upper limb loading. Flexing of the knee during swing phase has been used as a means of attempting to reduce these. It has been found that this has little effect because using knee flexion results in no change in the compensatory mechanisms required for swing foot clearance. This is because knee flexion can result in an increase in effective leg length, i.e. hip to toe distance. A combination of knee flexion and ankle dorsiflexion during swing phase is suggested as a means of reducing compensatory mechanisms. To examine this hypothesis, an orthosis incorporating knee and ankle flexion was constructed. The design used a novel mechanism to link the motion of the knee to that of the ankle, and also used functional electrical stimulation. Two spinal cord-injured subjects were trained to use the orthosis in two configurations. The first configuration used knee flexion and ankle dorsiflexion and the second configuration used knee flexion alone. Kinematic data were obtained to measure the compensatory mechanisms used during gait. The results showed that a combination of knee flexion and ankle dorsiflexion during swing phase resulted in a reduction in compensatory mechanisms when compared with knee flexion alone.

Muscle stretching for treatment and prevention of contracture in people with spinal cord injury

Contracture, or reduced joint mobility, is a common and disabling sequel of spinal cord injury. The primary intervention for the treatment and prevention of contracture is regular stretch to soft tissues. While the rationale for this intervention appears sound, the effectiveness of stretching has not been verified with well designed clinical trials. One recent randomised trial suggests there is no clinically worthwhile effect from a typical stretch protocol applied to spinal cord injured patients. Despite the negative results of this first trial, we argue that therapists should continue administering stretch for the treatment and prevention of contracture until the results of further studies emerge. To maximise the probability of attaining a clinically worthwhile effect, we suggest that therapists stretch soft tissues for long periods (at least 20 min, and perhaps for as long as 12 h a day). Practical suggestions are given on how to readily provide spinal cord injured patients with sustained stretch to key joints and muscle groups. Stretch is most likely to be effective if started before the onset of contracture. Soft tissues most at risk should be targeted, particularly if contracture is likely to impose functionally important limitations.

The effects of knee and ankle flexion on ground clearance in paraplegic gait

OBJECTIVE

To investigate the effects of knee flexion and ankle dorsiflexion on ground clearance during the swing phase of paraplegic gait.BACKGROUND. Limitations of currently available walking orthoses are high energy consumption and upper limb loading. Knee flexion in the swing phase has been suggested as a means of reducing these.METHODS. Kinematic data of paraplegic gait in two currently available orthoses were used to simulate the effects of knee flexion and ankle dorsiflexion on the swing foot ground clearance. This was used to validate a mathematical model of a simple ideal gait that was also developed.RESULTS. It was shown that the implementation of knee flexion alone leads to a loss or no change in ground clearance. Implementing knee flexion and ankle dorsiflexion can be used to increase ground clearance.CONCLUSION. Flexion at the knee and ankle during the swing phase can potentially be used to allow a reduction in compensatory mechanisms by easing swing foot ground clearance. RelevanceWalking orthoses are valuable in the clinical management of paraplegia, providing both physiological and psychological benefits. Functional improvements can only serve to encourage their greater usage.