The Acute Effects of a Robotic Exoskeleton Leg Orthosis on Balance, Gait, and Sit to Stand Function as well as Technology Usage Attitude Among Older Adults

Biomedical interventions that focus on limiting the effects of aging such as the decreased ability to quickly and safely sit and stand, as well as decreased balance and the ability to ambulate have become an important medical option for these public health concerns among the elderly. The use of robotic prosthetics with older adults may help eliminate the deleterious effects of aging that increase fall risk by changing the delineation of energy to different functional activities and increasing muscle strength. This study aimed to evaluate the acute therapeutic effects of a robotic exoskeleton dynamic orthosis, on participant’s functional movement, as well as approach and attitude towards biotechnology among the older adult population. Six assisted living older adult residents received unilateral robotic exoskeleton assisted therapy. Knee range of motion and baseline vitals including heart rate (HR), blood pressure (BP), respiratory rate, and oxygen saturation (SaO2%) were measured as well as standing, balance, and walking variables with and without the robotic exoskeleton. Biokinetic analysis software was used to describe talocrual, knee, and hip joint angles and identify movement limitations or alterations caused by the robotic exoskeleton. A technology usage and attitudes survey was administered before and after functional training and testing with the robotic exoskeleton. Mean balance scores without any robotic intervention and with 30% and 65% robotic assistance improved but were not statistically significant. Technology usage and attitudes survey mean scores for the pre-and post- robotic exoskeleton experience were unchanged. Mean HR, BP, respiration, and SaO2% remained statistically steady (P<0.05) throughout. Slight limitations were found in allowable biomechanical joint angles with the unit. The results suggest that a robotic exoskeleton dynamic orthosis may be helpful in the elderly with sit-to-stand, balance, and gait without being physiologically overtaxing, as well as being perceived by the elderly as nonthreatening regarding biotechnology.


Introduction
The older adult population is a group experiencing many physiological changes that are very influential and may inhibit them from maintaining their productivity in day to day life. From recognized increased sitting time which can lead to decreased mobility to a documented fear of falling in outdoor environments in older adults among assisted living facilities, a decline in lower extremity strength and ability often leads to reduced functional movement confidence in the elderly [1,2]. Decreased sit-to-stand, balance, and walking speed with a poor gait pattern are often attributed to muscular imbalance accompanied with low levels of energy production and utilization, as investigators have noted that the quadriceps muscles decrease their contractility force over the course of an individual's lifespan [3,4]. Slow gait speed in the older adult population has also been associated with early onset of disability secondary to decreased energy and muscular weakness and even death from noted heightened fall risks [5].
Many exercise studies with the elderly have shown a positive correlation with efficiency of movement [6]. The longer people are able to ambulate and perform different necessary activities of daily living, the longer they may remain independent and capable of engaging in society [7]. There have been several biomedical ambulatory intervention studies that focus on their effects of neurological insults such as stroke, spinal cord, and even brain injury [8][9][10][11][12].
However, there are very few studies that measure the functional outcome effects of such biomedical technology in the older adult population. Therefore, this study aimed to measure the physiological, biomechanical, and functional mobility effects of utilizing the Alter-G Bionic LegTM (Bionic Leg) a robotic exoskeleton dynamic orthosis (see Figure 1) among older adults. The Bionic Leg was designed to assist with knee extension through the use of external torque initiated with a pressure sensor located in the heel of the wearer's shoe, to assist with rehabilitation and mobility. This style of intervention is designed to assist the individual in utilizing his or her weakened leg. Prime candidates for this form of intervention would be those who do not have full function of their lower extremity or enough muscle strength to sustain a functional treatment session against gravity. Individuals that would potentially benefit from this robotic leg intervention are those who have difficulty with sit-to-stand because of the large demand that is placed on muscle groups that extend the lower extremity (i.e., the gluteal and quadriceps muscles) when raising one's body weight up against gravity. The purpose of this study was to determine the effects of the AlterG Bionic Leg TM on the Short Physical Performance Battery (SPPB) in the older adult population at 30% and 65% of robotic exoskeleton dynamic orthotic supported body weight and assess their experience regarding a technology usage and attitudes survey.
This study specifically addressed the following questions: a) Does using the Bionic Leg at 30% and 65% body weight support have an immediate effect on the results of the SPPB? b) Does using the Bionic Leg change the biomechanics of the individual during balance, walking, and sit-to-stand activities? c) Did the participants view on robotic exoskeleton technology change after using the Bionic Leg?

Study Population
Subjects were recruited residents of an assisted and independent living facility in Abilene, TX. Inclusion criteria included age (> 65 yrs), independent ambulation (with or without an assistive device) and who were alert and oriented of person,

Measuring Equipment and Procedure
Participants were fitted with the AlterG Bionic LegTM (see

Statistical Analysis
All the data were analyzed using SPSS 17.0 software (SPSS Inc., Chicago, IL) with statistical significance set at p<0.05. Repeated measures multivariate analysis of variance (RM-MANVOVA) tested for differences in the SPPB (static balance, gait speed, 5 times sit-to-stand) and MTUAS in the control condition and the 30% and 65% body weight, robotic support conditions with the Bionic Leg.

Discussion
Overall, the use of Bionic leg caused small clinical improvements in the static balance and 5 x sit-to-stand sections of the SPPB.
The bulkiness of the Bionic Leg limited knee flexion angles to 90-degrees, functionally reducing sit-to-stand ability. Research has previously found that 110-degrees of knee flexion is required in adults to rise comfortably from sit to stand [13]. In addition, due to device size regarding the unit width at the knee circumference,  heart rate in patients that participated in a strengthening routine with robotic intervention [15]. The decrease in resting heart rate shows an improvement in the cardiovascular system due to increased utilization of oxygen. This more efficient use of oxygen leads to greater energy reserves for the musculoskeletal system.
Theoretically, the use of robotic exoskeleton dynamic orthotics with older adults may help mitigate the deleterious, self-sustaining cycle that increases fall risk by changing instead the delineation of energy to different activities and increasing muscle strength. Interventions that increase functional movement in older adults are continuously being investigated due to the desire to improve the quality of life in this population.
Recent studies indicate that common reasons for falls are loss of balance, incorrect performance of transfers, feet getting stuck during movement, falls over an obstacle, and legs giving out [16][17][18]. A lifestyle with limited movement often increases fear of movement itself and lowers self-confidence. This cycle perpetuates itself and results in a greater risk for falls [19]. The results of this study provided additional information to the biomedical literature for elderly adults that need assistance with ambulation during their assisted or independent physical rehabilitation process.
Therefore, it is imperative that biomedical researchers continue the research and development process to assist older adults and their rehabilitation specialists utilize resources that will promote safe mobility.