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.

Gait analysis: clinical facts

Gait analysis is a well-established tool for the quantitative assessment of gait disturbances providing functional diagnosis, assessment for treatment planning, and monitoring of disease progress. There is a large volume of literature on the research use of gait analysis, but evidence on its clinical routine use supports a favorable cost-benefit ratio in a limited number of conditions. Initially gait analysis was introduced to clinical practice to improve the management of children with cerebral palsy. However, there is good evidence to extend its use to patients with various upper motor neuron diseases, and to lower limb amputation. Thereby, the methodology for properly conducting and interpreting the exam is of paramount relevance. Appropriateness of gait analysis prescription and reliability of data obtained are required in the clinical environment. This paper provides an overview on guidelines for managing a clinical gait analysis service and on the principal clinical domains of its application: cerebral palsy, stroke, traumatic brain injury and lower limb amputation.

Factors associated with poor outcomes in patients with lupus nephritis

The objective of this study was to identify the factors associated with important clinical outcomes in a case-control study of 213 patients with lupus nephritis. Included were 47% Hispanics, 44% African Americans and 9% Caucasians with a mean age of 28 years. Fifty-four (25%) patients reached the primary composite outcome of doubling serum creatinine, end-stage renal disease or death during a mean follow-up of 37 months. Thirty-four percent African Americans, 20% Hispanics and 10% Caucasians reached the primary composite outcome ( P < 0.05). Patients reaching the composite outcome had predominantly proliferative lupus nephritis (WHO classes: 30% III, 32% IV, 18% V and 5% II, P < 0.025) with higher activity index score (7 ± 6 versus 5 ± 5, P<0.05), chronicity index (CI) score (4 ± 3 versus 2 ± 2 unit, P<0.025), higher baseline mean arterial pressure (MAP) (111 ± 21 versus 102 ± 14 mmHg, P<0.025) and serum creatinine (1.9 ± 1.3 versus 1.3 ± 1.0 mg/dL, P<0.025), but lower baseline hematocrit (29 ± 6 versus 31 + 5%, P<0.025) and complement C3 (54 ± 26 versus 65 + 33 mg/dL, P<0.025) compared to controls. More patients reaching the composite outcome had nephrotic range proteinuria compared to controls (74% versus 56%, P<0.025). By multivariate analysis, CI (hazard ratio [95% CI] 1.18 [1.07-1.30] per point), MAP (HR 1.02 [1.00-1.03] per mmHg), and baseline serum creatinine (HR 1.26 [1.04-1.54] per mg/dL) were independently associated with the composite outcome. We concluded that hypertension and elevated serum creatinine at the time of the kidney biopsy as well as a high CI are associated with an increased the risk for chronic renal failure or death in patients with lupus nephritis.

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.

Suggested Guidelines for the Prescription of Orthotic Services, Device Delivery, Education, and Follow-up Care: A Multidisciplinary White Paper

OBJECTIVES

This article establishes needed guidelines for determining orthotic prescriber authority, documenting medical necessity, and ensuring continuity of care for patients needing orthoses. It also identifies "off-the-shelf" (OTS) devices that can safely and appropriately be delivered to patients without professional adjustment as well as those that cannot.

METHODS

A multidisciplinary task force made up of experts in orthopedics and physical medicine physicians, along with therapists and certified orthotists, applied a consensus approach to answer key questions: (i) When can a device be safely, effectively delivered to the patient OTS without professional guidance or education, and which caregivers have a role in that decision? (ii) What documentation is appropriate for physicians and other caregivers to determine medical necessity? (iii) What documentation/communication ensures continuity of care among physicians, therapists, and orthotists?

RESULTS

Guidelines developed for consideration of OTS orthoses include accepting documentation from collaborating caregivers, including therapists and orthotists; keeping that documentation as part of the patient's total medical record for clinical, medical necessity determinations and reimbursement purposes; and using the physician's prescription for the device as the key determinant of whether a device is delivered OTS or as a custom-fitted device.

CONCLUSION

This review provides expert guidance for patient safety, minimizing wasted expenditures, maximizing clinical outcomes, and providing efficient delivery of care for Medicare and other patients. Centers for Medicare and Medicaid Services guidelines should be directed toward recognizing the level of expertise of the orthotist, the value of their patient encounters, and their role in facilitating the timely, safe, and effective use of orthotic devices.

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.

OnabotulinumtoxinA muscle injection patterns in adult spasticity: a systematic literature review

Background

OnabotulinumtoxinA has demonstrated significant benefit in adult focal spasticity. This study reviews the injection patterns (i.e., muscle distribution, dosing) of onabotulinumtoxinA for treatment of adult spasticity, as reported in published studies.

Methods

A systematic review of clinical trials and observational studies published between 1990 and 2011 reporting data on muscles injected with onabotulinumtoxinA in adult patients treated for any cause of spasticity.

Results

28 randomized, 5 nonrandomized, and 37 single-arm studies evaluating 2,163 adult patients were included. The most frequently injected upper-limb muscles were flexor carpi radialis (64.0% of patients), flexor carpi ulnaris (59.1%), flexor digitorum superficialis (57.2%), flexor digitorum profundus (52.5%), and biceps brachii (38.8%). The most frequently injected lower-limb muscles were the gastrocnemius (66.1% of patients), soleus (54.7%), and tibialis posterior (50.5%). The overall dose range reported was 5–200 U for upper-limb muscles and 10–400 U for lower-limb muscles.

Conclusions

The reviewed evidence indicates that the muscles most frequently injected with onabotulinumtoxinA in adults with spasticity were the wrist, elbow, and finger flexors and the ankle plantar flexors. OnabotulinumtoxinA was injected over a broad range of doses per muscle among the studies included in this review, but individual practitioners should be mindful of local regulatory approvals and regulations.

Evidence-based review and assessment of botulinum neurotoxin for the treatment of adult spasticity in the upper motor neuron syndrome

Botulinum neurotoxin (BoNT) can be injected to achieve therapeutic benefit across a large range of clinical conditions. To assess the efficacy and safety of BoNT injections for the treatment of spasticity associated with the upper motor neuron syndrome (UMNS), an expert panel reviewed evidence from the published literature. Data sources included English-language studies identified via MEDLINE, EMBASE, CINAHL, Current Contents, and the Cochrane Central Register of Controlled Trials. Evidence tables generated in the 2008 Report of the Therapeutics and Technology Assessment Subcommittee of the American Academy of Neurology (AAN) review of the use of BoNT for autonomic disorders were also reviewed and updated. The panel evaluated evidence at several levels, supporting BoNT as a class, the serotypes BoNT-A and BoNT-B, as well as the four individual commercially available formulations: abobotulinumtoxinA (A/Abo), onabotulinumtoxinA (A/Ona), incobotulinumtoxinA (A/Inco), and rimabotulinumtoxinB (B/Rima). The panel ultimately made recommendations on the effectiveness of BoNT for the management of spasticity, based upon the strength of clinical evidence and following the AAN classification scale. While the prior report by the AAN provided recommendations for the use of BoNT as a class of drug, this report provides more detail and includes recommendations for the individual formulations. For the treatment of upper limb spasticity, the evidence supported a Level A recommendation for BoNT-A, A/Abo, and A/Ona, with a Level B recommendation for A/Inco; there was insufficient evidence to support a recommendation for B/Rima. For lower limb spasticity, there was sufficient clinical evidence to support a Level A recommendation for A/Ona individually and BoNT-A in aggregate; the clinical evidence for A/Abo supported a Level C recommendation; and there was insufficient information to recommend A/Inco and B/Rima (Level U). There is a need for further comparative effectiveness studies of the available BoNT formulations for the management of spasticity.