Exoskeletons for Personal Use After Spinal Cord Injury.

Before the development of robotic exoskeletons, mobility options beyond a wheelchair were very limited for most people lacking leg movement due to spinal cord injury (SCI). Over the years, robotic exoskeletons have become more widely available and now have the potential to be successfully used for personal use at home and in the community. However, it is important that users set realistic expectations. The features and capabilities of each robotic exoskeleton differ, and how exoskeletons are used may vary greatly between individuals. Robotic exoskeletons can allow individuals with SCI with varying levels of injury to safely and functionally walk for personal mobility or exercise. The following special communication will discuss important considerations surrounding exoskeleton use including feasibility, safety, cost, speed, and potential health benefits of using an exoskeleton for everyday life for people with SCI.

Preliminary Assessment of a Hand and Arm Exoskeleton for Enabling Bimanual Tasks for Individuals With Hemiparesis.

The design and preliminary assessment of a semi-powered hand and arm exoskeleton is described. The exoskeleton is designed to enable bimanual activities of daily living for individuals with chronic, upper-limb hemiparesis resulting from stroke. Specifically, the device augments the user's grasp strength and ability to extend the affected hand for bimanual tasks and supplements wrist and elbow stability while conducting these tasks. The exoskeleton is battery-powered and self-contained with all electronics and power units placed within the device structure. A preliminary assessment of the exoskeleton was performed with three subjects having right-sided upper-limb motor deficit resulting from stroke. For subjects with limited hand and arm functionality, the exoskeleton increased grasp strength and improved the ability to perform representative bimanual tasks.

FES Coupled With A Powered Exoskeleton For Cooperative Muscle Contribution In Persons With Paraplegia.

This paper describes the effects of a novel functional electrical stimulation (FES) system which has been integrated in a powered exoskeleton to provide up to 10 channels of stimulation to users with paraplegia via surface electrodes. Experimental data collected from three users with spinal cord injury (SCI) indicate the system reduced the exoskeleton motor torques necessary to perform sit-to-stand transitions in the exoskeleton. All subjects exhibited reduced muscle spasticity immediately after walking in the exoskeleton with FES. Additionally, one subject with stretch-reflex spasms exhibited increased joint excursion and reduced exoskeleton motor torques required to achieve over-ground gait when FES was incorporated.

Mobility Outcomes Following Five Training Sessions with a Powered Exoskeleton.

BACKGROUND: Loss of legged mobility due to spinal cord injury (SCI) is associated with multiple physiological and psychological impacts. Powered exoskeletons offer the possibility of regained mobility and reversal or prevention of the secondary effects associated with immobility. OBJECTIVE: This study was conducted to evaluate mobility outcomes for individuals with SCI after 5 gait-training sessions with a powered exoskeleton, with a primary goal of characterizing the ease of learning and usability of the system. METHODS: Sixteen subjects with SCI were enrolled in a pilot clinical trial at Shepherd Center, Atlanta, Georgia, with injury levels ranging from C5 complete to L1 incomplete. An investigational Indego exoskeleton research kit was evaluated for ease of use and efficacy in providing legged mobility. Outcome measures of the study included the 10-meter walk test (10 MWT) and the 6-minute walk test (6 MWT) as well as measures of independence including donning and doffing times and the ability to walk on various surfaces. RESULTS: At the end of 5 sessions (1.5 hours per session), average walking speed was 0.22 m/s for persons with C5-6 motor complete tetraplegia, 0.26 m/s for T1-8 motor complete paraplegia, and 0.45 m/s for T9-L1 paraplegia. Distances covered in 6 minutes averaged 64 meters for those with C5-6, 74 meters for T1-8, and 121 meters for T9-L1. Additionally, all participants were able to walk on both indoor and outdoor surfaces. CONCLUSIONS: Results after only 5 sessions suggest that persons with tetraplegia and paraplegia learn to use the Indego exoskeleton quickly and can manage a variety of surfaces. Walking speeds and distances achieved also indicate that some individuals with paraplegia can quickly become limited community ambulators using this system.

Acute Cardiorespiratory and Metabolic Responses During Exoskeleton-Assisted Walking Overground Among Persons with Chronic Spinal Cord Injury.

BACKGROUND: Lower extremity robotic exoskeleton technology is being developed with the promise of affording people with spinal cord injury (SCI) the opportunity to stand and walk. The mobility benefits of exoskeleton-assisted walking can be realized immediately, however the cardiorespiratory and metabolic benefits of this technology have not been thoroughly investigated. OBJECTIVE: The purpose of this pilot study was to evaluate the acute cardiorespiratory and metabolic responses associated with exoskeleton-assisted walking overground and to determine the degree to which these responses change at differing walking speeds. METHODS: Five subjects (4 male, 1 female) with chronic SCI (AIS A) volunteered for the study. Expired gases were collected during maximal graded exercise testing and two, 6-minute bouts of exoskeleton-assisted walking overground. Outcome measures included peak oxygen consumption (V̇O2peak), average oxygen consumption (V̇O2avg), peak heart rate (HRpeak), walking economy, metabolic equivalent of tasks for SCI (METssci), walk speed, and walk distance. RESULTS: Significant differences were observed between walk-1 and walk-2 for walk speed, total walk distance, V̇O2avg, and METssci. Exoskeleton-assisted walking resulted in %V̇O2peak range of 51.5% to 63.2%. The metabolic cost of exoskeleton-assisted walking ranged from 3.5 to 4.3 METssci. CONCLUSIONS: Persons with motor-complete SCI may be limited in their capacity to perform physical exercise to the extent needed to improve health and fitness. Based on preliminary data, cardiorespiratory and metabolic demands of exoskeleton-assisted walking are consistent with activities performed at a moderate intensity.

Assisted movement with proprioceptive stimulation reduces impairment and restores function in incomplete spinal cord injury.

OBJECTIVE: To test whether treatment with assisted movement with enhanced sensation (AMES) using vibration to the antagonist muscle would reduce impairments and restore upper limb function in people with incomplete tetraplegia. DESIGN: Prospective, pre-post study. SETTING: Laboratory and rehabilitation hospital. PARTICIPANTS: We recruited 15 arms from 10 individuals (8 men; mean age, 40.5 y; mean years postspinal cord injury [SCI], 3) with chronic, incomplete tetraplegia. INTERVENTION: Two or three 20-minute sessions per week over 9 to 13 weeks (25 sessions total) on the AMES device, which combines repeated movement with targeted vibration to the antagonist muscle. MAIN OUTCOME MEASURES: Strength and active motion tests on the AMES device; International Standards for the Neurological Classification of SCI (ISNCSCI) motor and sensory examinations; Modified Ashworth Scale (MAS); grasp and release test (GRT); Van Lieshout Test (VLT); and Capabilities of Upper Extremity questionnaire (CUE). RESULTS: The AMES strength test scores improved significantly in metacarpophalangeal flexion (P=.024) and extension (P=.007) and wrist flexion (P=.001) and extension (P<.000). The AMES active motion scores improved in the hand (P=.001) and wrist (P=.001). The MAS and ISNCSCI scores remained unchanged, whereas the GRT scores increased (P=.025). Post hoc analysis showed a trend from pre- to posttreatment (P=.068) and a significant change from pretreatment to 3-month follow-up (P=.046). There was no significant change in the VLT (P=.951) or the CUE (P=.164). Five of the 10 participants reported a return of sensation to the digits after the first, second, or third treatment session. CONCLUSIONS: People with chronic, incomplete tetraplegia may experience improvements in impairments and function after treatment on a device combining assisted movement and proprioceptive stimulation. Further investigation is warranted.