The LSU Reciprocation-Gait Orthosis

Comorbidities and medical complexities of mobility device users: a retrospective study

OBJECTIVE

To determine the medical complexities and comorbidities of individuals who utilise wheeled mobility devices. As well as, to examine costly events including the number of urinary tract infections (UTIs), hospitalizations, urgent care(UC)/emergency department (ED) visits that are commonly seen in this population over a period of time one year prior to and one year post receiving their wheeled mobility equipment.

DESIGN/SETTING

A retrospective data review of 857 individual medical charts at a Level 1 Trauma Hospital and Clinic System.

PARTICIPANTS

330 male and female (24-92 years old) mobility device users with a wide range of diagnoses, of which: 56 used manual wheelchairs (MWC),138 scooters (POV), 123 power wheelchairs without integrated standing (PWC), and 13 power wheelchairs with integrated standing (iS-PWC).

RESULTS

Overall, 92% (n = 304) had at least three medical comorbidities and medical complexities. The most common comorbidity was pain (91%). A change was noted in a lower incidence of UTIs in those using an iS-PWC, respectively 23% with at least 1 UTI in the year prior to and 8% in the year after the mobility device evaluation.

CONCLUSIONS

The large number of comorbidities and medical complexities amongst all mobility device users is concerning. The burden and the accompanying healthcare costs of this population is high. The potential that iS-PWC and other interventions could have on reducing these issues should be explored further.Implications of rehabilitationRegardless of a person's primary diagnosis or the wheeled mobility device they use, 100% have at least one and 92% have at least three comorbidities and medical complexities if they spend the majority of their day sittingThe high healthcare cost situations such as Emergency Department visits, Urgent Care visits, hospitalizations, and Urinary Tract Infections are present across those that use all mobility device types and the means to potentially reduce these incidences should be further exploredThe introduction of integrated standing within a power wheelchair, as a means to minimize the frequency of comorbidities and medical complications, should also be investigated further.

Exoskeletal solutions to enable mobility with a lower leg fracture in austere environments

The treatment and evacuation of people with lower limb fractures in austere environments presents unique challenges that assistive exoskeletal devices could address. In these dangerous situations, independent mobility for the injured can preserve their vital capabilities so that they can safely evacuate and minimize the need for additional personnel to help. This expert view article discusses how different exoskeleton archetypes could provide independent mobility while satisfying the requisite needs for portability, maintainability, durability, and adaptability to be available and useful within austere environments. The authors also discuss areas of development that would enable exoskeletons to operate more effectively in these scenarios as well as preserve the health of the injured limb so that definitive treatment after evacuation will produce better outcomes.

Effect of Reciprocating Gait Orthosis with Hip Actuation on Upper Extremity Loading during Ambulation in Patient with Spinal Cord Injury: A Single Case Study

Reciprocating gait orthosis (RGO) is a traditional passive orthosis that provides postural stability and allows for independent upright ambulation with the assistance of walking aids, such as crutches, canes, and walkers. Previous follow-up studies of patients with RGOs have indicated a high frequency of nonusage. One of the main reasons for avoiding the use of RGOs is the excessive upper extremity loading induced by walking aids. The purpose of this study was to investigate the effect of hip actuation on the upper extremity loading induced by crutches when ambulating with an RGO. One female individual with a chronic complete spinal cord injury classified as ASIA A participated in this study. We compared the upper extremity loading during ambulation when individualized hip assistive forces were applied on the RGO (POWERED condition) and when wearing the RGO without actuation (RGO condition). Upper extremity loading was assessed by measuring the forces acting on the crutches. Compared with the RGO condition, the average upper extremity loading per unit distance and per unit time were lower for the POWERED condition by 15.21% (RGO: 0.307 ± 0.056 and POWERED: 0.260 ± 0.034 %bw·m−1) and by 21.19% (RGO: 0.120 ± 0.020 and POWERED: 0.094 ± 0.011 %bw·s−1), respectively. We believe that a substantial reduction in upper extremity loading during ambulation provided by hip actuation holds promise to promote long-term RGO use and enable patients with paraplegia to perform frequent and intensive rehabilitation training. As this is a single case study, subsequent studies should aim to verify this effect through a higher number of patients and to different injury levels.

Effectiveness of an innovative hip energy storage walking orthosis for improving paraplegic walking: A pilot randomized controlled study

BACKGROUND

The high energy cost of paraplegic walking using a reciprocating gait orthosis (RGO) is attributed to limited hip motion and excessive upper limb loading for support. To address the limitation, we designed the hip energy storage walking orthosis (HESWO) which uses a spring assembly on the pelvic shell to store energy from the movements of the healthy upper limbs and flexion-extension of the lumbar spine and hip and returns this energy to lift the pelvis and lower limb to assist with the swing and stance components of a stride. Our aim was to evaluate gait and energy cost indices for the HESWO compared to the RGO in patients with paraplegia.

METHODS

The cross-over design was used in the pilot study. Twelve patients with a complete T4-L5 chronic spinal cord injury underwent gait training using the HESWO and RGO. Gait performance (continuous walking distance, as well as the maximum and comfortable walking speeds) and energy expenditure (at a walking speed of 3.3m/min on a treadmill) were measured at the end of the 4-week training session.

RESULTS

Compared to the RGO, the HESWO increased continuous walking distance by 24.7% (P<0.05), maximum walking speed by 20.4% (P<0.05) and the comfortable walking speed by 15.3% (P<0.05), as well as decreasing energy expenditure by 13.9% (P<0.05).

CONCLUSION

Our preliminary results provide support for the use of the HESWO as an alternative support for paraplegic walking.

Effect of exoskeletal joint constraint and passive resistance on metabolic energy expenditure: Implications for walking in paraplegia

An important consideration in the design of a practical system to restore walking in individuals with spinal cord injury is to minimize metabolic energy demand on the user. In this study, the effects of exoskeletal constraints on metabolic energy expenditure were evaluated in able-bodied volunteers to gain insight into the demands of walking with a hybrid neuroprosthesis after paralysis. The exoskeleton had a hydraulic mechanism to reciprocally couple hip flexion and extension, unlocked hydraulic stance controlled knee mechanisms, and ankles fixed at neutral by ankle-foot orthoses. These mechanisms added passive resistance to the hip (15 Nm) and knee (6 Nm) joints while the exoskeleton constrained joint motion to the sagittal plane. The average oxygen consumption when walking with the exoskeleton was 22.5 ± 3.4 ml O₂/min/kg as compared to 11.7 ± 2.0 ml O₂/min/kg when walking without the exoskeleton at a comparable speed. The heart rate and physiological cost index with the exoskeleton were at least 30% and 4.3 times higher, respectively, than walking without it. The maximum average speed achieved with the exoskeleton was 1.2 ± 0.2 m/s, at a cadence of 104 ± 11 steps/min, and step length of 70 ± 7 cm. Average peak hip joint angles (25 ± 7°) were within normal range, while average peak knee joint angles (40 ± 8°) were less than normal. Both hip and knee angular velocities were reduced with the exoskeleton as compared to normal. While the walking speed achieved with the exoskeleton could be sufficient for community ambulation, metabolic energy expenditure was significantly increased and unsustainable for such activities. This suggests that passive resistance, constraining leg motion to the sagittal plane, reciprocally coupling the hip joints, and weight of exoskeleton place considerable limitations on the utility of the device and need to be minimized in future designs of practical hybrid neuroprostheses for walking after paraplegia.

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.

EVALUATION THE PATTERN AND MAGNITUDE OF THE LOADS APPLIED ON MTKRGO ORTHOSIS DURING WALKING OF PARAPLEGIC SUBJECTS

Various kinds of orthosis have been designed for paraplegic subjects to stand and walk. They have been designed based on this assumption that most of the loads applied on the orthosis (OR) and body complex is transmitted by OR. In this study, it was aimed to determine the role of OR to transmit the loads by use of strain gauge system. Three spinal cord injury subjects, with lesion between T12 and L1, were recruited in this study. A motion analysis system with a Kistler force plate was used to collect the kinetic and kinematic parameters. Moreover, the loads applied on the OR were determined by use of strain gauges attached on the lateral bar of OR. The pattern of the loads applied on the complex, OR and body, differed from that of OR. Nearly 43% of adduction moment was transmitted by OR. In contrast the role of OR to transmit the flexing/extending moments and vertical force is negligible. The results of strain gauge and motion analysis systems differed completely from each other's. As the strain gauge show the absolute values of the loads applied on OR, it is recommended using its result in order to design an OR for paraplegic subjects.

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).

Modeling effects of sagittal-plane hip joint stiffness on reciprocating gait orthosis-assisted gait

Upright ambulation is believed to improve quality of life for persons with lower-limb paralysis (LLP). However, ambulatory orthoses for persons with LLP, like reciprocating gait orthoses (RGOs), result in a slow, exhausting gait. Increasing the hip joint stiffness of these devices may improve the efficiency of RGO-assisted gait. The small, diverse population of RGO users makes subject recruitment challenging for clinical investigations. Therefore, we developed a lower-limb paralysis simulator (LLPS) that enabled nondisabled persons to exhibit characteristics of RGO-assisted gait, thereby serving as surrogate models for research. For this study, tests were conducted to determine the effects of increased hip joint stiffness on gait of nondisabled persons walking with the LLPS. A motion capture system, force plates, and spirometer were used to measure the hip flexion, crutch ground reaction forces (GRFs), and oxygen consumption of subjects as they walked with four different hip joint stiffness settings. Increasing the hip joint stiffness decreased hip flexion during ambulation but did not appear to affect the crutch GRFs. Walking speed was observed to initially increase with increases in hip joint stiffness, and then decrease. These findings suggest that increasing hip joint stiffness may increase walking speed for RGO users.

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.

Determination of the influence of walking with orthosis on bone osteoporosis in paraplegic subjects based on the loads transmitted through the body

BACKGROUND

Spinal cord injury is a damage to spinal cord that results in loss of function and mobility below the level of injury. The patients use various orthoses to improve their general health, to decrease bone osteoporosis, and to improve bone mineral density. It was controversial if how much percentage of the loads applied on an orthosis and body complex is transmitted by orthosis. Therefore, it was aimed to determine the magnitude of the loads transmitted by orthosis to find the influence of walking with orthosis on bone mineral density.

METHODS

Three spinal cord injured subjects were recruited in this study. They were trained to walk with a reciprocal gait orthosis. The loads applied on the hip joint of the orthosis and body complex, anatomy and orthosis were measured by use of strain gauges and motion analysis system.

FINDINGS

The mean values of the force and moments transmitted by the orthosis were significantly less than those of the complex. The mean values of adduction moment transmitted through the orthosis and body complex and by the orthosis structure were 1.06 and 0.49N·m/body weight, respectively.

INTERPRETATION

As a higher percentage of loads were transmitted by body than the orthosis, it can be concluded that walking with orthosis could improve bone mineral density, due to the role of bone in transmission of the loads. Therefore, it is recommended that spinal cord injured subjects walk with an orthosis in order to reduce bone osteoporosis, especially for a long period of time.

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.

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.

The influence of walking with an orthosis on bone mineral density by determination of the absolute values of the loads applied on the limb

Spinal cord injury is damage to the spinal cord that results in loss of mobility and sensation below the level of injury. Most patients use various types of orthoses to stand and walk. It has been claimed that walking and standing with orthosis reduces bone osteoporosis, improves joint range of motion and decreases muscle spasm. Unfortunately, there are discrepancies regarding the clinical effects of walking and standing on bone mineral density. The aim of this research was to find the absolute values of the loads transmitted by body and orthosis in walking with use of an orthosis. 5 normal subjects were recruited to stand and walk with a new design of reciprocal gait orthosis. The loads transmitted through the orthosis and anatomy was measured by use of strain gauge and motion analysis systems. It has been shown that the loads applied on the anatomy were significantly more than that transmitted through the orthosis. Moreover, the patterns of the forces and moments of the orthosis and body completely differed from each other. As the most part of the loads applied on the complex transmitted by anatomy in walking with an orthosis, walking with orthosis can influence bone mineral density.

Modeling the walking patterns of Reciprocating Gait Orthosis users with a novel Lower Limb Paralysis Simulator

A mechanical Lower Limb Paralysis Simulator (LLPS) was developed for able-bodied persons to model the gait of Reciprocating Gait Orthosis (RGO) users. The purpose of this study was to determine if able-bodied subjects ambulating with the LLPS exhibited gait characteristics typical of RGO users. Five able-bodied persons were trained to ambulate with the LLPS and underwent a motion gait analysis. LLPS users were found to exhibit gait patterns that were characteristic of RGO-assisted gait.

Determination of the Loads Applied on the Anatomy and Orthosis During Ambulation With a New Reciprocal Gait Orthosis

Various types of orthoses have been designed to enable individuals with Spinal Cord Injury (SCI) to stand and walk; however, all of these orthoses have certain problems. A new type of lower limb orthosis was designed and evaluated while five normal subjects walked. Appropriate types of strain gauges were attached on the lateral bar of the orthosis, near the hip joint, in order to measure the loads transmitted through the orthosis. The force applied on the foot, orthosis, and crutch, and the moment applied on the hip joint complex and orthosis were measured during walking with the orthosis. This study showed that the loads applied on the orthosis differed from that reported in the literature and the pattern of the moment and force transmitted through the orthosis was different from those applied on the anatomical structures. The results of this research can be used to enhance lower limb orthotic design for individuals with SCI.

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 modern era of orthotics

The past 40 years has seen the field of orthotics change from a craft-based industry into a modern clinical specialty. The author describes his personal view of some of the most important developments during this period in the areas of manufacturing and materials, patient/orthosis matching, biomechanics, joint design and standards. Some likely areas of future development are suggested.

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.

Functional electrical stimulation after spinal cord injury: current use, therapeutic effects and future directions

Repair of the injured spinal cord by regeneration therapy remains an elusive goal. In contrast, progress in medical care and rehabilitation has resulted in improved health and function of persons with spinal cord injury (SCI). In the absence of a cure, raising the level of achievable function in mobility and self-care will first and foremost depend on creative use of the rapidly advancing technology that has been so widely applied in our society. Building on achievements in microelectronics, microprocessing and neuroscience, rehabilitation medicine scientists have succeeded in developing functional electrical stimulation (FES) systems that enable certain individuals with SCI to use their paralyzed hands, arms, trunk, legs and diaphragm for functional purposes and gain a degree of control over bladder and bowel evacuation. This review presents an overview of the progress made, describes the current challenges and suggests ways to improve further FES systems and make these more widely available.

Analysis of trunk movement in orthotic gait of paraplegics

In an orthotic gait of paraplegics, a leg restriction and motor paralysis result in a significant loading. In this study, we address to quantify a relationship between the loading, leg restriction and motor paralysis, and analyze lumbar joint trajectories in the orthotic gait of paraplegic subjects and the ordinary and orthotic gaits of a normal subject using an inverted pendulum model. For the leg restriction, the trajectories are located anterior to an equilibrium point of the inverted pendulum, and the loading is higher due to the influence of gravity moment. Comparing the orthotic gait kinematics of paraplegic with that of normal in the horizontal plane, the lumbar joint trajectory in the paraplegic subjects was rectilinear shape, while that in the normal subject was curved in the direction to the equilibrium point. The loading is lower in the curved trajectory than in the straight trajectory because of the trade-off between gravity and inertia. These results suggest that the leg restriction and motor paralysis lead to the increase of the distance between the trunk movement and the equilibrium point of an inverted pendulum, which causes significant loading in the orthotic gate of paraplegics.

Stability analysis of paraplegic standing while wearing an orthosis

Paraplegics can maintain a standing posture, called the "C-posture", while wearing an orthosis. The significant feature of the C-posture is that the body's center of mass is located behind the hip joint. In this study, we investigate the C-posture mechanism and assess the relationship between posture and stability, the aim being to restore standing function. We first measured the standing postures of paraplegic subjects wearing an orthosis. The subjects maintained the standing posture for 30 s. Next, assuming the C-posture to be an equilibrium attractor in the musculoskeletal system, we used a dynamic model of the musculoskeletal system to analyze the relationship between posture and stability, and also to assess the influence of ankle stiffness. We calculated the standing posture on the basis of a return map. The calculated standing postures show some features of the C-posture. The stability analysis revealed that, despite a limitation in the range of stable postures, the C-posture is more stable than the postures of normal people. The results suggest that although the C-posture is an appropriate posture for paraplegic standing, sufficient ankle stiffness and an appropriate alignment of ankle angle are necessary and preventing hip flexion movements is desirable.

Prediction of gait outcome with the knee-ankle-foot orthosis with medial hip joint in patients with spinal cord injuries: a study using recursive partitioning analysis

STUDY DESIGN

Retrospective study of the degree of gait independence achieved by persons with spinal cord injury (SCI) using knee-ankle-foot orthosis with a medial single hip joint (MSH-KAFO).

OBJECTIVE

To examine the effects of the neurological level, degree of paresis, age, and inhibitory physical/other factors on the gait with a MSH-KAFO in patients with SCIs.

SETTING

Three university hospitals and two rehabilitation hospitals in Japan.

METHODS

The 45 patients (36 men, nine women) examined included 10 with injuries in the cervical cord between C6 and C8 (group C), 20 with injuries in the upper-middle thoracic cord between T4 and T10 (group UT), and 15 with injuries in the lower thoracic-lumbar cord between T12 and L1 (group TL). Mean age was 34.0 years (range 16-68 years). Of these patients, 13 used the Walkabout, four used the gear joint, and 28 used the Primewalk as the medial hip joint. Recursive partitioning, which predicted the final status of gait from the level, degree of paresis, age, and inhibitory factors, was performed, and a decision tree for gait was constructed. Inhibitory factors were spasticity, involuntary spasms or muscle contractions, pain, contracture, weakness of the upper extremities, and decreased motivation to perform gait exercise. The degree of gait independence was rated on the following five-point scale: outdoor independent gait (5 points), indoor independent gait (4 points), indoor supervised gait (3 points), indoor assisted gait (2 points), and gait within parallel bars (1 point). New branches were added to the decision tree for gait based on the clinical experience, thereby constructing a new decision tree.

RESULTS

The coincident ratio between the value predicted on the basis of the decision tree of gait and the value actually observed was 53.3%. The coincident ratio between the value predicted on the basis of the modified decision tree of gait and the actually observed value was 68.9%.

CONCLUSION

The results provide valuable information to medical teams that may assist prescription of gait orthoses.

Development of a novel type of shoe to improve the efficiency of knee-ankle-foot orthoses with a medial single hip joint (Primewalk orthoses): a novel type of shoe for Primewalk orthosis

The purpose of the study was to develop and evaluate a new heel cushion in shoes for use with knee-ankle-foot orthoses having a medial single hip joint (Primewalk orthoses) in order to improve walking velocity and efficiency. Primewalk orthoses and shoes were made for a 24-year-old man having paraplegia with flaccid paresis (level T-7; grade A, ASIA impairment scale) of 2 years' duration. Walking exercises were assigned. Shoes were modified with the sole made of hard rubber and the addition of soft rubber heel cushions. The walking speed, centre of foot pressure during walking, and ground reaction force were evaluated. The patient also subjectively assessed the devices. The modifications to the shoes resulted in a 1.94-fold increase in walking speed (8.6 to 16.7 m/min), a 1.87-fold increase in step length (16.7 to 31.3 cm) and a 54.8% decrease in the physiological cost index (7.7 to 3.48 beats/min). The centre of foot pressure during walking was found to deviate towards the lateral margin of the foot. The horizontal rotation of the pelvis increased simultaneously. The patient reported increased amplitude of flail motion of the trunk and decreased burden to the upper limbs. It was concluded that the modified new heel cushion of the shoe provided freedom to the lower legs and thereby increased walking efficiency.

New technical advances in swivel walkers

Swivel walkers were commonly prescribed for children with complete thoracic lesion myelomeningocele in the 1970s and 80s, when the incidence of spina bifida in the UK was of the order of 3 per 100,000 live births. The advent of reciprocal walking orthoses provided a more suitable alternative for those with good upper limb and trunk function, and swivel walkers were then used primarily for very young or more severely disabled patients. Pre-natal screening has dramatically reduced the incidence of spina bifida in the UK and subsequently swivel walkers have been used in a wider range of pathology, including spinal muscular atrophy, multiple sclerosis, muscular dystrophy and other neurological conditions that lead to lower limb dysfunction. The detail design of these devices has been adapted to accommodate the specific problems encountered in these conditions. In particular the designs have been updated to: enable very young patients to be more readily fitted at the age of 1 year; allow the walking mechanisms to be conveniently adjusted for easier ambulation when weakness or lack of confidence inhibits performance; permit simple adjustment to a standing frame mode to enhance stability in situations of increased risk; promote manual handling practice that is compatible with the National Health Service (NHS) policy of compliance with relevant regulations. To underpin appropriate prescription and safe supply the NHS Procurement Agency have encouraged the development of a common course for all types of swivel walker.

A prototype of an adjustable advanced reciprocating gait orthosis (ARGO) for spinal cord injury (SCI)

OBJECTIVE

To develop a reciprocating gait orthosis which could be used in different sized patients.

DESIGN

Clinical trial and orthotic development.

SETTING

A large rehabilitation hospital in Rome, Italy

PATIENTS AND METHODS

To carry out this project normal reciprocating gait orthosis parts were used. The device was modified to adjust the hip-ankle height, and the hip-hip distance. It was tested, by five patients already walking with standard ARGO, to evaluate the performances of the orthosis. The device has been tested on seven newly injured patients fulfilling specific criteria of different height and weight.

MAIN OUTCOME MEASURES

Prototype suitability; patients appreciation.

RESULTS

The device can be used for persons between 1.60 m and 1.85 m tall, weighing up to 100 kg. The orthosis allows an upright position without the use of the hands, and walking with a walker or with two canes. The foot orthosis cover sizes 36-40 (British 3-7) and 41-45 (British 7-11). With the exception of donning, doffing and lifting, the walking performances of the prototype and the general appreciation is comparable with those of a standard device. After a short period of training all seven patients were able to walk in the parallel bars. All of them expressed general appreciation for the device; despite this only four patients wanted the orthosis, two refused it and one has not decided yet.

CONCLUSIONS

The prototype allows the same standing and walking performances of normal ARGO. It could be used in spinal cord injury patients to let them test the potential of the device and thus be useful in the effort to reduce the percentage of ARGO rejection.

Evaluation of safety and reliability in an infant reciprocal walking orthosis

In response to new demands for infant walking orthoses consideration was given to the development of a device for this category of patient. A specially developed hip joint with the required structural properties (Woollam et al., 2001) provided an opportunity for this development. Earlier structural assessment, and limited cyclic load testing of key elements of the orthosis (primarily the body brace), confirmed that a safe device for evaluation with patients could, theoretically, be produced. A provisional prototype was therefore designed and manufactured for initial structural testing of the complete infant orthosis (Stallard et al., 2001). Efficiency of walking is strongly influenced by the lateral rigidity of the orthosis. Monitoring the structural performance of the provisional infant design indicated it would equal or improve on the stiffness of that achieved in the adult specification. Additionally, relative strength was comparable with the adult version, which has proven to be safe and reliable in many years of routine prescription. This, together with the limited cyclic testing of the complete orthosis (Stallard et al., 2001), gave confidence that it was safe to proceed with controlled field evaluation of the infant design when supplied as a rehabilitation engineering device within the provisions of an ISO9001 and EN46001 QA System. This additional study of controlled patient use, and further representative cyclic load testing in parallel with the field evaluation, had established the long-term structural safety of the orthosis. Wider application is now to be introduced through completion of the EC (European Community) Medical Devices Directive formalities.

Reciprocating gait prosthesis for the bilateral hip disarticulation amputee

This paper describes the design, manufacture and use of a new prosthesis which produced reciprocating gait for a bilateral hip disarticulation amputee. A special mechanism used the hip extension moment during weight bearing to drive the contralateral limb through the swing phase. The user rapidly attained efficient and safe reciprocating gait, together with simple donning and doffing. The success of this project has major implications for hip disarticulation amputees in terms of profound improvements of their independence and self-esteem.

Percutaneous implantation of iliopsoas for functional neuromuscular stimulation

Hip flexion is required for walking and stair climbing. Percutaneous electrical stimulation of the iliopsoas muscle is a potentially useful and reliable method of providing hip flexion in individuals who are paralyzed. In this study, groin, lateral abdominal, and paraspinal approaches of percutaneous electrode implantation for electrical stimulation of the iliopsoas muscle are described. The paraspinal approach using stimulation of the second and third lumbar roots gave the best hip flexion response; however, it often was accompanied by unwanted stimulation of the hip adductor and abdominal muscles. Wire breakage and electrode movement were the most common causes for failure of maintaining hip flexion. The paraspinal approach, using double helix electrodes, provided an average of 110 weeks of functional hip flexion sufficient for walking. It is feasible to implant electrodes in the iliopsoas muscle. An open technique for permanent implantation of intramuscular electrodes is being developed to selectively stimulate the iliopsoas, which will extend the range and duration of hip flexion that will allow stair climbing in individuals who are paraplegic.

A reciprocal walking orthosis hip joint for young paediatric patients with a variety of pathological conditions

A growing trend in the use of reciprocal walking orthoses for infant paraplegic patients, and their application for control of the lower limbs in very young total body involved cerebral palsy patients, has created a need for smaller components. A prototype design of a hip joint has been produced which provides the following features: adjustable range of flexion/extension control; override on stops to permit sitting; high lateral rigidity; no lateral bearing play; very high rigidity in the sagittal plane; low friction bearings; high resistance to torque about the vertical axis. In addition a size envelope which is more in keeping with the dimensions of infant patients was an important objective. Comparisons were made of the computed structural properties of the prototype joint and existing routinely available standard orthotic hip joints. In each plane of loading the prototype joint had the highest identified structural property. The hinge-bearing material was tested in a representative joint with 200,000 cycles of typical loading. It was also field tested on adult orthoses over a minimum of a 12-month period with the most vigorous of walkers. In neither test did excessive play develop. The mechanical properties of the joint were established using tests advocated in the British Standard on testing lower limb orthosis knee joints. These showed the joint had structurally equivalent performance to a successful reciprocal walking orthosis hip joint, and that the mode of failure was essentially ductile in nature. Production development of the joint is now being undertaken.

Biomechanical study of gait using an intelligent brace

We have developed a new long leg brace fitted with a computer-controlled knee joint that allows the user to go up and down a slope and stairs. Using this new brace, we analyzed gait under various conditions in ten normal men in terms of dynamic electromyography. Walking up a slope with normal step produced discharges in the leg muscles other than the gastrocnemius lateral head before and after the heel-strike on the ground, which indicated the absorption of the impact of landing. Going down a slope with controlled step resulted in lower activities of the tibialis anterior and the gastrocnemius lateral head than doing so with non-locked step or locked step. In subjects walking up stairs with tandem gait, the large discharges of the gastrocnemius lateral head that were observed in the late stance phase with normal step disappeared when the brace was applied. These results indicated that the muscle activity levels decreased during controlled walking with this new brace, and that the new brace can compensate for reduced muscle strength of the lower leg during walking. Kinematic analysis of walking revealed no significant difference between normal walking and controlled walking under any walking conditions.

A rear support walking frame for severely disabled children with cerebral palsy: initial development

Ambulation for patients with total body involved cerebral palsy poses greater problems than those encountered in providing reciprocal walking for thoracic lesion paraplegic subjects. Experience with a prototype system showed that an orthosis which controls the movement of the lower limbs, in combination with a walking frame giving anterior support, enables such patients to walk. Despite shortcomings which restricted the use of the system to an indoor environment it provided a sound basis on which to examine walking frames to address the problems which had been identified. A review of these devices showed that the most effective means of achieving this aim is the use of a wheeled walking frame which provides vertical support and truncal alignment via a sprung pantograph mounted to the rear of the patient (rear support walking frames). Trials were conducted with two existing rear support walking frames. These indicated their potential for severely disabled patients, but also identified the need for higher stiffness in the structure and more sensitive control of vertical support to be achieved if effective ambulation in a wider range of environments was to be made possible for the target group. Prototypes based on an existing frame, which took account of the specification requirements, were produced for four new total body involved cerebral palsy patients with the same degree of walking dysfunction. Three of the patients were able to walk in a much wider variety of environments than any patient in the original system. A number of other issues related to transfer and steering were identified as requiring further development.

Postural control during stance in paraplegia: effects of medially linked versus unlinked knee-ankle-foot orthoses

OBJECTIVE

To investigate the effect of medially linking knee-ankle-foot orthoses (KAFOs) on postural stability and sway during (1) quiet standing and (2) functional activities for persons with spinal cord injury (SCI).

DESIGN

A randomized, mixed design, with the factors being activity (quiet standing and two function-mimicking tasks), SCI (present or not), and type of orthosis used in SCI group (linked or unlinked KAFO).

PARTICIPANTS

Nine men with T5 to T12 paraplegia, 8 of whom had complete lesions and 1 with some sacral sparing (American Spinal Injury Association grade B) without proprioception, matched to 9 able-bodied men.

MAIN OUTCOME MEASURES

Mean amplitude of sway and sway path in anteroposterior and mediolateral directions, derived from center of pressure measurements on a force platform.

RESULTS

All men with SCI were able to stand unsupported and perform function-mimicking activities in medially linked KAFOs; however, when wearing unlinked KAFOs only 5 could maintain balance during quiet stance and 3 could maintain balance during activity. Significant differences were found between linked and unlinked KAFOs; side-to-side mean amplitude of sway was less and sway path was greater for SCI subjects when they wore the linked KAFOs.

CONCLUSION

Medial linkage of bilateral KAFOs provides an effective strategy to improve stability and increase postural control for persons with SCI, facilitating performance of functional activities during standing without upper limb support.

Feasibility study on a composite material construction technique for highly stressed components in reciprocal walking orthoses for paraplegic patients

Reciprocal walking for thoracic level paraplegic patients using reciprocal walking orthoses has become a routine treatment option. Two general design options are currently deployed within an overall treatment regime. Research has shown that one has better walking efficiency but is cosmetically less acceptable to the patient. Design analysis and experimental data have shown that a major factor in improved walking efficiency is the lateral stiffness of the body brace section of the orthosis. This is the area where problems of cosmesis in the more efficient orthosis are perceived because of the employment of metallic structures. The use of composite material structures to achieve shapes which are more closely conforming to the patient is an attractive option. However the brittle nature of these materials makes it unlikely that the requirement for the ductile failure mode will be achieved from a straightforward moulding. A new construction technique has been devised which has the potential to provide a safe failure mode with greater stiffness and lighter weight. This feasibility study has been undertaken to demonstrate its potential so that further work can be justified which will provide sufficient evidence to support a patent application. The successful outcome of the study, in which stiffness was increased by 60 per cent with a weight reduction of 50 per cent and a failure mode comparable with the original metal structure, suggests that further work will enable the dilemma in the choice of orthosis to be resolved.

Cost of walking and locomotor impairment

The aim of the present study was to evaluate the importance and the necessity of metabolic measurements to quantify locomotor impairment in a clinical context. Oxygen consumption, heart rate, pulmonary ventilation and walking speed were measured during locomotion in 14 normal subjects, used as a control group, and 82 patients with different pathologies [hemiparetic, paraparetic, tetraparetic, orthopaedic and paraplegic patients, who walked using a reciprocating gait orthosis (RGO)]. The subjects were characterized on the basis of a cumulative impairment score (CIS), based on clinical scales commonly used to evaluate impairment and disability in locomotion. Appropriate indices of energy, cardiac and ventilatory costs expressed per metre walked, globally called physiological costs, were obtained. It resulted that the most comfortable speed (MCS) of normal subjects was significantly higher than that of each group of patients. Normal subjects' physiological costs were found to be significantly lower than those of patients who needed either a device or the help of a person to walk. All measured parameters correlated significantly with each other. The MCS was found to be the most correlated parameter with the CIS (r = 0.8), and therefore it must be considered the best single measurement, if only one is to be used. Measurements more precise than MCS, such as the physiological costs, may be necessary in clinical trials.

Functional electrical stimulation

In the health-care professions, electrical stimulation is used for three purposes: to aid diagnosis; as a therapeutic tool; and to restore lost or damaged functions. Functional electrical stimulation (FES) and functional neurostimulation (FNS) are terms which are more or less interchangeable, and which encompass the third of these purposes. FES itself can also be conveniently divided into three classes, according to purpose: the restoration of sensor functions; the restoration of skeleto-motor functions; and the restoration of autonomic functions. Potentially, a fourth class would comprise devices restoring cognitive or psychological functions, but no such devices are clinically available as yet. The methods and devices which are currently available for providing FES are reviewed, as are the sorts of result and benefit that may be expected from them. The structure and emphasis of the review is on the clinical applications and the relevant anatomical and neurophysiological considerations and this approach is chosen for two main reasons. Firstly, the clinical, anatomical, and physiological considerations are independent of technological change and development, so they will not become quickly out of date. Secondly, the author is a clinician by profession, and an engineer only by inclination. The functional aims of FES methods will continue to develop as a result of experience gained following the introduction and use of successful devices, and these evolutionary improvements will come from within the FES programme; but the engineering embodiment of those devices may be revolutionized at any time by technological advances coming from elsewhere.

Ambulation with the reciprocating-gait orthosis. Experience in 15 children with myelomeningocele or paraplegia

We reviewed 15 children with spina bifida or paraplegia who have used a reciprocating-gait orthosis between 1985 and 1995. All were nonfunctional ambulators. The level of the spinal lesions ranged from Th10 to L3. The mean age of fitting the orthosis was 5 years. 8 children have stopped using it at an average age of 10 years. The maximum ambulation level with the orthosis was a community ambulator in 4 children, household ambulator in 9 children and 2 remained nonfunctional ambulators. The average daily use was 6 hours by community ambulators to 0.5 hours nonfunctional ambulators. Bilateral dislocations of the hip, mild flexion deformities of the hips and knees and scoliosis were well tolerated with orthotic wear. Since functional ambulation could be achieved in 6 children with no quadriceps power, the use of this orthosis can be advocated for upper lumbar and low thoracic lesions. Strong motivation, realistic goals and expectations, the ability to participate in a training program and journeys for frequent orthosis repairs are of importance for successful use of this orthosis.

Evaluation of a training program for persons with SCI paraplegia using the Parastep 1 ambulation system: part 1. Ambulation performance and anthropometric measures

OBJECTIVE

To describe performance parameters and effects on anthropometric measures in spinal cord injured subjects training with the Parastep 1 system.

DESIGN

Before-after trial.

SETTING

Human spinal cord injury applied research laboratory.

PARTICIPANTS

Thirteen men and 3 women with thoracic (T4-T11) motor-complete spinal cord injury: mean age, 28.8yrs; mean duration postinjury, 3.8yrs.

INTERVENTION

Thirty-two functional neuromuscular stimulation ambulation training sessions using a commercially available system (Parastep-1). The hybrid system consists of a microprocessor-controlled stimulator and a modified walking frame with finger-operated switches that permit the user to control the stimulation parameters and activate the stepping.

OUTCOME MEASURES

Distance walked, time spent standing and walking, pace, circumferential (shoulders, chest, abdomen, waist, hips, upper arm, thigh, and calf) and skinfold (chest, triceps, axilla, subscapular, supraillium, abdomen, and thigh) measurements, body weight, thigh cross-sectional area, and calculated lean tissue.

RESULTS

Statistically significant changes in distance, time standing and walking, and pace were found. Increases in thigh and calf girth, thigh cross-sectional area, and calculated lean tissue, as well as a decrease in thigh skinfold measure, were all statistically significant.

CONCLUSIONS

The Parastep 1 system enables persons with thoracic-level spinal cord injuries to stand and ambulate short distances but with a high degree of performance variability across individuals. The factors that influence this variability have not been completely identified.

Further development of hybrid functional electrical stimulation orthoses

In this study two aspects of hybrid functional electrical stimulation (FES) orthoses were investigated: joint motion constraints and FES control strategies. First, the effects of joint motion constraints on the gait of normal subjects were investigated using modern motion analysis systems, including electromyogram (EMG) and heart rate measurements. An orthosis was developed to impose joint motion constraints; the knee and ankle could be fixed or free, and the hip joint could rotate independently or coupled, according to a preset flexion-extension coupling ratio (FECR). Compared with a 1:1 hip FECR, a 2:1 hip FECR was associated with a reduced energy cost and increased speed and step length. The knee flexion during swing significantly reduced energy cost and increased walking speed. Ankle plantar flexion reduced the knee flexing moment during the early stance phase. Second, trials on 3 paraplegic subjects were conducted to implement some of these findings. It appeared that the 2:1 FECR encouraged hip flexion and made leg swing easier. A simple FES strategy increased walking speed and step length and reduced crutch force impulse using fixed orthotic joints.

Further development of hybrid functional electrical stimulation orthoses

It is recognised that, in paraplegic walking with reciprocating gait orthoses, inadequate hip flexion angles may contribute to the low walking speed and high energy cost. In this study a new orthotic hip joint was developed which had a 2:1 flexion extension coupling ratio. Experiments on paraplegic subjects were conducted to evaluate this orthotic hip joint. It was found that the new hip joint was associated with a reduced energy cost and increased step length. A simple application of FES assisted hip flexion further increased walking speed and step length and reduced energy cost and crutch force impulse.