Feasibility and outcomes of supplemental gait training by robotic and conventional means in acute stroke rehabilitation.

INTRODUCTION: Practicality of implementation and dosing of supplemental gait training in an acute stroke inpatient rehabilitation setting are not well studied but can have positive impact on outcomes. OBJECTIVES: To determine the feasibility of early, intense supplemental gait training in inpatient stroke rehabilitation, compare functional outcomes and the specific mode of delivery. DESIGN AND SETTING: Assessor blinded, randomized controlled trial in a tertiary Inpatient Rehabilitation Facility. PARTICIPANTS: Thirty acute post-stroke patients with unilateral hemiparesis (≥ 18 years of age with a lower limb MAS ≤ 3). INTERVENTION: Lokomat® or conventional gait training (CGT) in addition to standard mandated therapy time. MAIN OUTCOME MEASURES: Number of therapy sessions; adverse events; functional independence measure (FIM motor); functional ambulation category (FAC); passive range of motion (PROM); modified Ashworth scale (MAS); 5 times sit-to-stand (5x-STS); 10-m walk test (10MWT); 2-min walk test (2MWT) were assessed before (pre) and after training (post). RESULTS: The desired supplemental therapy was implemented during normal care delivery hours and the patients generally tolerated the sessions well. Both groups improved markedly on several measures; the CGT group obtained nearly 45% more supplemental sessions (12.8) than the Lokomat® group (8.9). Both groups showed greater FIM improvement scores (discharge - admission) than those from a reference group receiving no supplemental therapy. An overarching statistical comparison between methods was skewed towards a differential benefit (but not significant) in the Lokomat® group with medium effect sizes. By observation, the robotic group completed a greater number of steps, on average. These results provide some evidence for Lokomat® being a more efficient tool for gait retraining by providing a more optimal therapy "dose". CONCLUSIONS: With careful planning, supplemental therapy was possible with minimal intrusion to schedules and was well tolerated. Participants showed meaningful functional improvement with relatively little supplemental therapy over a relatively short time in study.

An examination of undergraduate research in the field of biomechanics across multiple US-based institutions.

Undergraduate research is commonly performed in many STEM disciplines and has a wide array of benefits for students, laboratories, principal investigators, and institutions. While many fields have assessed best practices and the cost-benefit analysis of incorporating undergraduates in research, this has not yet been addressed in biomechanics. This paper represents the perspectives of seven members of the American Society of Biomechanics (ASB) Teaching Biomechanics Interest Group (TBIG). These TBIG members discussed their own experience regarding the opportunities, challenges, and benefits of undergraduate research and this perspective paper presents the commonalities found during these interactions. The TBIG members reported that undergraduate research was assessed similarly to graduate student research, which often led to an underestimation of productivity for both the student and overall lab output. While undergraduate researchers are not often responsible for publications and grant funding, they are instrumental in lab productivity in other ways, such as through human subject approvals, conference abstract presentations, student thesis projects, and more. Students benefit from these experiences, not necessarily by continuing in research, but by learning skills and making connections which further them in any career. While this perspective presents the experience of seven professors in the United States, future studies should further assess the cost-benefit relationship of working with undergraduates in biomechanics research on a global scale. A clearer picture of this analysis could benefit students, faculty, and administrators in making difficult decisions about lab productivity and assessment.

Robotics for Lower Limb Rehabilitation.

Improving walking function is a desirable outcome in rehabilitation and of high importance for social and vocational reintegration for persons with neurologic-related gait impairment. Robots for lower limb gait rehabilitation are designed principally to help automate repetitive labor-intensive training during neurorehabilitation. These include tethered exoskeletons, end-effector devices, untethered exoskeletons, and patient-guided suspension systems. This article reviews the first 3 categories and briefly mentions the fourth. Research is needed to further define the therapeutic applications of these devices. Additional technical improvements are expected regarding device size, controls, and battery life for untethered devices.

Powered Exoskeletons for Walking Assistance in Persons with Central Nervous System Injuries: A Narrative Review.

Individuals with central nervous system injuries are a large and apparently rapidly expanding population-as suggested by 2013 statistics from the American Heart Association. Increasing survival rates and lifespans emphasize the need to improve the quality of life for this population. In persons with central nervous system injuries, mobility limitations are among the most important factors contributing to reduced life satisfaction. Decreased mobility and subsequently reduced overall activity levels also contribute to lower levels of physical health. Braces to assist walking are options for greater-functioning individuals but still limit overall mobility as the result of increased energy expenditure and difficulty of use. For individuals with greater levels of mobility impairment, wheelchairs remain the preferred mobility aid yet still fall considerably short compared with upright bipedal walking. Furthermore, the promise of functional electrical stimulation as a means to achieve walking has yet to materialize. None of these options allow individuals to achieve walking at speeds or levels comparable with those seen in individuals with unimpaired gait. Medical exoskeletons hold much promise to fulfill this unmet need and have advanced as a viable option in both therapeutic and personal mobility state, particularly during the past decade. The present review highlights the major developments in this technology, with a focus on exoskeletons for lower limb that may encompass the spine and that aim to allow independent upright walking for those who otherwise do not have this option. Specifically reviewed are powered exoskeletons that are either commercially available or have the potential to restore upright walking function. This paper includes a basic description of how each exoskeleton device works, a summation of key features, their known limitations, and a discussion of current and future clinical applicability.

A Randomized Comparison of the Biomechanical Effect of Two Commercially Available Rocker Bottom Shoes to a Conventional Athletic Shoe During Walking in Healthy Individuals.

Rocker bottom shoes have recently gained considerable popularity, likely in part because of the many purported benefits, including reducing joint loading and toning muscles. Scientific inquiry about these benefits has not kept pace with the increased usage of this shoe type. A fundamental premise of rocker bottom shoes is that they transform hard, flat, level surfaces into more uneven ones. Published studies have described a variety of such shoes-all having a somewhat rounded bottom and a cut heel region or a cut forefoot region, or both (double rocker). Despite the fundamentally similar shoe geometries, the reported effects of rocker bottom shoes on gait biomechanics have varied considerably. Ten healthy subjects agreed to participate in the present study and were given appropriately sized Masai Barefoot Technology (St. Louis, MO), Skechers(™) (Manhattan Beach, CA), and New Balance (Boston, MA) conventional walking shoes. After a 12-day accommodation period, the subjects walked wearing each shoe while 3-dimensional motion and force data were collected in the gait laboratory. The key findings included (1) increased trunk flexion, decreased ankle plantarflexion range, and reduced plantarflexion moment in the early stance; (2) increased ankle dorsiflexion and knee flexor moment in the midstance; (3) decreased peak ankle plantarflexion in the late stance; and (4) decreased ankle plantarflexion and decreased hip flexor and knee extensor moments in the pre-swing and into swing phase. The walking speed was unconstrained and was maintained across all shoe types. A biomechanical explanation is suggested for the observed changes. Suggestions for cautions are provided for using rocker bottom shoes in patients with neuromuscular insufficiency.

Using kinematics and a dynamical systems approach to enhance understanding of clinically observed aberrant movement patterns.

The objective of this technical paper is to demonstrate how graphing kinematic data to represent body segment coordination and control can assist clinicians and researchers in understanding typical and aberrant human movement patterns. Aberrant movements are believed to be associated with musculoskeletal pain and dysfunction. A dynamical systems approach to analysing movement provides a useful way to study movement control and coordination. Continuous motion angle-angle and coupling angle-movement cycle graphs provide information about coordinated movement between body segments, whereas phase-plane graphs provide information about neuromuscular control of a body segment. Examples demonstrate how a dynamical systems approach can be used to represent (1) typical movement patterns of the lumbopelvic and shoulder regions; (2) aberrant coordination in an individual with low back pain who presented with altered lumbopelvic rhythm; and (3) aberrant control of shoulder movement in an individual with observed scapular dysrhythmia. Angle-angle and coupling angle-movement cycle graphs were consistent with clinical operational definitions of typical and altered lumbopelvic rhythm. Phase-plane graphs illustrated differences in scapular control between individuals having typical scapular motion and an individual with scapular dysrhythmia. Angle-angle, coupling angle-movement cycle, and phase-plane graphs provide information about the amount and timing of segmental motion, which clinicians assess when they observe movements. These approaches have the potential to (1) enhance understanding of typical and aberrant movement patterns; (2) assist with identifying underlying movement impairments that contribute to aberrant movements: and (3) improve clinicians' ability to visually assess and categorize functional movements.

Differentiating ability in users of the ReWalk(TM) powered exoskeleton: an analysis of walking kinematics.

The ReWalk(TM) powered exoskeleton assists thoracic level motor complete spinal cord injury patients who are paralyzed to walk again with an independent, functional, upright, reciprocating gait. We completed an evaluation of twelve such individuals with promising results. All subjects met basic criteria to be able to use the ReWalk(TM)--including items such as sufficient bone mineral density, leg passive range of motion, strength, body size and weight limits. All subjects received approximately the same number of training sessions. However there was a wide distribution in walking ability. Walking velocities ranged from under 0.1m/s to approximately 0.5m/s. This variability was not completely explained by injury level The remaining sources of that variability are not clear at present. This paper reports our preliminary analysis into how the walking kinematics differed across the subjects--as a first step to understand the possible contribution to the velocity range and determine if the subjects who did not walk as well could be taught to improve by mimicking the better walkers.

Assessment of gait sensitivity norm as a predictor of risk of falling during walking in a neuromusculoskeletal model.

Quantifying the risk of falling (falls risk) would be helpful in treating people with gait disorders. The gait sensitivity norm (GSN) is a stability measure that correlates well to risk of falling in passive dynamic walkers but has not been evaluated on humans or human-like walking models. We assessed the correlation of GSN to risk of falling in a neuromusculoskeletal (NMS) walking model. Specifically, we evaluated the correlation of GSN to the actual disturbance rejection (ADR) of the model and the sensitivity of this relationship to gait parameter, Poincaré section selection and steady state variability correction. Statistically significant results at p<0.05 were obtained for some of the gait indicators evaluated at the point in the gait cycle where they were most variable. The correlation between GSN and ADR was sensitive to gait indicator and Poincaré sections evaluated but not to steady state variability correction. The current work suggests some simple steps to reduce the sensitivity of GSN to arbitrary and subjective factors. Overall, the findings support the potential of GSN to be a clinically applicable measure of falls risk. Further study is required to identify methods to more definitively select the various factors within the GSN calculation and to confirm its ability to predict falls risk in human subjects.

The ReWalk powered exoskeleton to restore ambulatory function to individuals with thoracic-level motor-complete spinal cord injury.

OBJECTIVE: The aim of this study was to assess the safety and performance of ReWalk in enabling people with paraplegia due to spinal cord injury to carry out routine ambulatory functions. DESIGN: This was an open, noncomparative, nonrandomized study of the safety and performance of the ReWalk powered exoskeleton. All 12 subjects have completed the active intervention; three remain in long-term follow-up. RESULTS: After training, all subjects were able to independently transfer and walk, without human assistance while using the ReWalk, for at least 50 to 100 m continuously, for a period of at least 5 to 10 mins continuously and with velocities ranging from 0.03 to 0.45 m/sec (mean, 0.25 m/sec). Excluding two subjects with considerably reduced walking abilities, average distances and velocities improved significantly. Some subjects reported improvements in pain, bowel and bladder function, and spasticity during the trial. All subjects had strong positive comments regarding the emotional/psychosocial benefits of the use of ReWalk. CONCLUSIONS: ReWalk holds considerable potential as a safe ambulatory powered orthosis for motor-complete thoracic-level spinal cord injury patients. Most subjects achieved a level of walking proficiency close to that needed for limited community ambulation. A high degree of performance variability was observed across individuals. Some of this variability was explained by level of injury, but other factors have not been completely identified. Further development and application of this rehabilitation tool to other diagnoses are expected in the future.

The impact of adding trunk motion to the interpretation of the role of joint moments during normal walking.

Biomechanical model assumptions affect the interpretation of the role of the muscle or joint moments to the segmental power estimated by induced acceleration analysis (IAA). We evaluated the effect of modeling the pelvis and trunk segments as two separate segments (8 SM) versus as a single segment (7 SM) on the segmental power, support of the body, knee and hip extension acceleration produced by the joint moments during the stance phase of normal walking. Significant differences were observed in the contribution of the stance hip abductor and extensor moments to support, ipsilateral knee and hip acceleration, and ipsilateral thigh and upper body power. The primary finding was that the role of the stance hip moment in generating ipsilateral thigh and upper body power differed based on degrees of freedom in the model. Secondarily, the magnitude of contributions also differed. For example, the hip abductor and extensor moments showed greater contribution to support, hip and knee acceleration in the 8 SM. IAA and segment power analysis are sensitive to the degrees of freedom between the pelvis and trunk. There is currently no gold standard by which to evaluate the accuracy of IAA predictions. However, modeling the pelvis and trunk as separate segments is closer to the anatomical architecture of the body. An 8 SM appears to be more appropriate for estimating the role of joint moments, particularly to motion of more proximal segments during normal walking.