How a Diverse Research Ecosystem Has Generated New Rehabilitation Technologies: Review of NIDILRR’s Rehabilitation Engineering Research Centers

Over 50 million United States citizens (1 in 6 people in the US) have a developmental, acquired, or degenerative disability. The average US citizen can expect to live 20% of his or her life with a disability. Rehabilitation technologies play a major role in improving the quality of life for people with a disability, yet widespread and highly challenging needs remain. Within the US, a major effort aimed at the creation and evaluation of rehabilitation technology has been the Rehabilitation Engineering Research Centers (RERCs) sponsored by the National Institute on Disability, Independent Living, and Rehabilitation Research. As envisioned at their conception by a panel of the National Academy of Science in 1970, these centers were intended to take a “total approach to rehabilitation”, combining medicine, engineering, and related science, to improve the quality of life of individuals with a disability. Here, we review the scope, achievements, and ongoing projects of an unbiased sample of 19 currently active or recently terminated RERCs. Specifically, for each center, we briefly explain the needs it targets, summarize key historical advances, identify emerging innovations, and consider future directions. Our assessment from this review is that the RERC program indeed involves a multidisciplinary approach, with 36 professional fields involved, although 70% of research and development staff are in engineering fields, 23% in clinical fields, and only 7% in basic science fields; significantly, 11% of the professional staff have a disability related to their research. We observe that the RERC program has substantially diversified the scope of its work since the 1970’s, addressing more types of disabilities using more technologies, and, in particular, often now focusing on information technologies. RERC work also now often views users as integrated into an interdependent society through technologies that both people with and without disabilities co-use (such as the internet, wireless communication, and architecture). In addition, RERC research has evolved to view users as able at improving outcomes through learning, exercise, and plasticity (rather than being static), which can be optimally timed. We provide examples of rehabilitation technology innovation produced by the RERCs that illustrate this increasingly diversifying scope and evolving perspective. We conclude by discussing growth opportunities and possible future directions of the RERC program

Analysis of driving backward in an electric-powered wheelchair

The purpose of this study was to examine the influences of caster orientations and driving speeds on the reverse directional stability of electric-powered wheelchairs. An experiment was set up to record wheelchair trajectories and ground reaction forces/moments for the front caster wheels and rear wheels when a wheelchair initiates reverse motions at six initial caster orientations and three desired driving speeds. A kinematic model as well as a dynamic model were developed to simulate the wheelchair motion and conduct a parametric study of different factors on wheelchair reverse directional stability. The experimental and simulation results show agreement, both of which indicate that different caster orientations at the start of reverse driving introduce disturbances and the faster the intended speed, the less deviation of the wheelchair from its desired heading. The center of gravity (CG) was also found to be a dominant influence on the reverse directional stability of power wheelchairs. © 2004 IEEE

Tips and Falls during Electric-Powered Wheelchair Driving: Effects of Seatbelt Use, Legrests, and Driving Speed

Objective: To measure the response of a test dummy while traversing common obstacles encountered by users of electric-powered wheelchairs (EPWs) to determine whether optimal wheelchair fit, use of seatbelts, and driving speed affect the frequency and severity of EPW tips and falls. Design: Repeated-measures comparison study. Setting: Constructed environment both in and around a Veterans Affairs medical center. Participant: A 50th percentile Hybrid II anthropometric test dummy (ATD) was used to simulate a person driving an EPW. Interventions: The ATD was driven in 4 different EPWs over commonly encountered obstacles at speeds of 1 and 2m/s, with and without the use of a seatbelt, and at varying legrest heights. Main Outcome Measures: The response and motion of the ATD were observed and recorded as no fall, loss of control (the ATD falls forward or sideways but remains in the EPW), the ATD falls out of the EPW, or the EPW tips completely. Results: A total of 97 adverse events out of 1700 trials were recorded: 88 were losses of control (instability) and 9 were ATD falls. No complete tips of any EPW occurred. Univariate statistical analysis indicated a significant relationship between the adverse events and the use of seatbelts, legrest condition, and test obstacles (P<.05). A mixed-model analysis confirmed the significant relationships between the adverse events and the use of seatbelts, legrest condition, and test obstacles (P<.05). However, the mixed model indicated that (1) there was no significant relationship between the adverse events and driving speed and (2) no one obstacle was designated to be the most problematic. Conclusion: Persons who use EPWs should use seatbelts and legrests while driving their EPWs, and clinicians should include common driving tasks when assessing the proper set-up of EPWs

Comparison of three different models to represent the wrist during wheelchair propulsion

Due to the high incidence of secondary wrist injury among manual wheelchair users, recent emphasis has been placed on the investigation of wheelchair propulsion biomechanics. Accurate representation of wrist activity during wheelchair propulsion may help to elucidate the mechanisms contributing to the development of wrist injuries. Unfortunately, no consensual wrist biomechanical model has been established. In order to determine if different methodologies obtain similar results, this investigation created and compared three different wrist models: 1) a fixed joint center placed between the styloids (midstyloid joint center); 2) a joint center with 2° of freedom computed from de Leva's joint center data; and 3) a floating joint center. Results indicate that wrist flexion and extension angles are highly consistent between models, however, radial and ulnar deviation angles vary considerably. Mean maximum right flexion angles were found to be 3.5°, 2.2°, and 5.0° for the midstyloid, de Leva, and floating joint center models, respectively. Extension angles were 22.3°, 23.6°, and 23.6°, respectively. Mean maximum right radial deviation angles for the midstyloid, de Leva, and floating joint center models were 26.0°, 26.9°, and 45.1°, respectively, and ulnar deviation angles were found to be 30.5°, 38.8°, and 10.2°, respectively. This information is useful when comparing kinematic studies and further supports the need for consensual methodology

Range of motion and stroke frequency differences between manual wheelchair propulsion and pushrim-activated power-assisted wheelchair propulsion

Background/Objective: The objective of this study was to examine the use and efficacy of a pushrim-activated power-assist wheelchair (PAPAW) in the reduction of upper extremity range of motion (ROM) and stroke frequency in manual wheelchair users. Methods: Ten manual wheelchair users were evaluated using a repeated-measures design with and without the use of a PAPAW for maximum ROM of shoulder flexion/extension, abduction/adduction, internal/external rotation, and horizontal flexion/extension; elbow flexion/extension; wrist flexion/extension, supination/pronation, and ulnar/radial deviation; and stroke frequency. Participants propelled a Quickie 2 manual wheelchair configured as a PAPAW and their own wheelchair on a computer-controlled dynamometer at 3 different resistance levels and 2 different speeds. Results: The use of the PAPAW significantly (P < 0.05) decreased shoulder flexion/extension and horizontal flexion/extension, elbow flexion/extension, and wrist flexion/extension and ulnar/radial deviation for many speed and resistance combinations. Univariate analysis revealed that stroke frequency was unaltered in all cases. Conclusion: These findings provide the foundation for studying the utility of the PAPAW in reducing the risk of upper limb injury and neuropathy in the manual wheelchair user population