Jonathan Pearlman

Towards the development of an effective technology transfer model of wheelchairs to developing countries.

Purpose.And estimated 20 – 100 million wheelchairs are needed in developing countries. Efforts to provide wheelchairs either through donations or by starting small-scale workshops have been made for decades, but estimates suggest that less than 1 million wheelchairs have been provided. We undertook this study to better understand why these efforts have not met the need, and to investigate if other technology transfer models may be successful for wheelchair provision. Methods.We performed a literature review, discussed our own experiences with wheelchair technology transfer, and used our expertise to develop a model for wheelchair technology transfer. Results.Previous efforts have not met the need because: (1) donated wheelchairs were typically inappropriate for the user, and (2) small-scale workshops are not easily scalable for the large-scale production needed. Three additional technology transfer models exist—manufacturing, globalization, and multi-modal—that have not been widely demonstrated or discussed in the literature. Our experience with the manufacturing model suggests that it could potentially provide the large volumes of appropriate wheelchairs needed in certain regions. Lastly, we present a framework comparing the important characteristics of each model: required input, sustainability, appropriateness, and the potential impact. Conclusions.While most efforts to provide wheelchairs to developing countries are helpful, we show that expansion of the manufacturing and globalization model to provide wheelchairs may be necessary if the supply will meet the demand.

Evaluation of aluminum ultralight rigid wheelchairs versus other ultralight wheelchairs using ANSI/RESNA standards.

Previous studies found that select titanium ultralight rigid wheelchairs (TURWs) had fewer equivalent cycles and less value than select aluminum ultralight folding wheelchairs (AUFWs). The causes of premature failure of TURWs were not clear because the TURWs had different frame material and design than the AUFWs. We tested 12 aluminum ultralight rigid wheelchairs (AURWs) with similar frame designs and dimensions as the TURWs using the American National Standards Institute/Rehabilitation Engineering and Assistive Technology Society of North America and International Organization for Standardization wheelchair standards and hypothesized that the AURWs would be more durable than the TURWs. Across wheelchair models, no significant differences were found in the test results between the AURWs and TURWs, except in their overall length. Tire pressure, tube-wall thickness, and tube manufacturing were proposed to be the factors affecting wheelchair durability through comparison of the failure modes, frames, and components. The frame material did not directly affect the performance of AURWs and TURWs, but proper wheelchair manufacture and design based on mechanical properties are important.

Longitudinal assessment of vibrations during manual and power wheelchair driving over select sidewalk surfaces

Wheelchair users rely on their wheelchairs for mobility for extended periods of time every day. According to the International Standards Organization 2631-1 standard on human vibration, individuals in a seated position when exposed to whole-body vibrations (WBV) are at risk of injury. This study evaluated vibration exposure during manual and power wheelchair driving over nine sidewalk surfaces and differences in vibration exposure over 3 years. Ten nondisabled subjects were asked to drive a manual wheelchair at 1 m/s and a power wheelchair at 1 m/s and 2 m/s over nine sidewalk surfaces while WBV were measured at the seat and footrest of the wheelchair. At 1 m/s, significant differences existed between surfaces and years at both the seat and the footrest for the manual and power wheelchair users. At 2 m/s, significant differences existed between surfaces and years at the seat and the footrest for power wheelchair users. Our results show that both manual and power wheelchair users may be at risk for secondary injuries from WBV when traveling over certain surfaces.

Vibration exposure of individuals using wheelchairs over sidewalk surfaces

According to the International Standards Organization 2631-1 standard on human vibration, individuals in a seated position are at risk of injury due to whole-body vibrations when exposed for long periods of time. Wheelchair users fit this description perfectly; however, little research has been conducted to evaluate the amount of vibration transmitted to a wheelchair user. The vibration exposure produced by traversing nine surfaces was evaluated by having 10 individuals without disabilities propel over them in both a manual wheelchair at 1 m/s and a powered wheelchair at 1 and 2 m/s. Root-mean squared (RMS) vertical vibration was examined to determine if differences existed between surfaces. At 1 m/s for both the manual and the powered wheelchair the 8-mm bevel interlocking concrete surface produced significantly higher RMS vertical vibration than the other surfaces. At 2 m/s in the powered wheelchair, the poured concrete surface (control) produced the significantly highest RMS vertical vibration. Based on the manual and power wheelchair results of this study, use of selected ICPI pavers would be acceptable for any route traveled by individuals using wheelchair. Furthermore, a 90° herringbone pattern is preferred over the 45° pattern, and it is recommended that for safety reasons regarding vibration exposure a bevel of less than 6 mm should be used.

Design, development and testing of a low-cost electric powered wheelchair for India

Purpose. To design and develop an appropriate, low-cost electric powered wheelchair (EPW) for the Indian subcontinent. Method. We performed the following multi-phase design process: (1) Conceptual design; (2) System design, Prototype I fabrication, focus group testing with Indian stakeholders (n = 29); (3) System re-design, Prototype II fabrication and user trials with US (n = 5) and Indian (n = 25) subjects. Results. (1) Preliminary investigations revealed that a conventional EPW design was infeasible due to the high component cost. Instead, we constrained our design to incorporate a single drive motor and manual steering, with the option of upgrading to power steering where economically feasible. (2) The first prototype was fabricated out of easily available, low-cost materials. Focus group testing demonstrated feasibility of the design and revealed differences between stakeholder groups. (3) Prototype II incorporated feedback from the first focus group and a needs assessment. US subjects provided valuable design advice prior to the India trials. Indian subjects travelled further in the SIMPL-EPW than their own manual wheelchair (MWC). Depending on spinal injury level, Indian subjects found the entire (tetraplegia) or outdoor portion (paraplegia) of the obstacle course significantly less challenging in the SIMPL-EPW compared with their own MWC. Conclusions. We demonstrated a useful and successful multi-phase design approach for developing assistive technology for developing regions.

Differences Between Manufacturers in Reported Power Wheelchair Repairs and Adverse Consequences Among People With Spinal Cord Injury

OBJECTIVE To compare the frequency of power wheelchair (PWC) repairs and consequences experienced over a 6-month period by individuals with spinal cord injury (SCI) who use a PWC ≥40h/wk, based on manufacturer, seating functions, Healthcare Common Procedure Coding System (HCPCS) group, and model, and over time. DESIGN Convenience observational sample survey. SETTING Spinal Cord Injury Model System centers. PARTICIPANTS Individuals with SCI (N=945) who use a PWC ≥40h/wk. INTERVENTIONS Not applicable. MAIN OUTCOME MEASURES Number of required wheelchair repairs and resulting consequences (ie, being stranded, missing work/school, or missing a medical appointment). RESULTS Rates of required repairs (47.6%-63.3%) and consequences (26.7%-40.7%) were high across manufacturers. Differences between manufacturers were found among PWCs without seating functions (P<.001-.008) and among group 2 wheelchairs (P=.007). Across the 10 most prescribed wheelchairs in this study, 54.5% to 73.9% of users required 1 or more repairs over a 6-month period. Increases in the number of repairs were also found for several PWC manufacturers with time. Differences were found in participant age, working status, years since injury, and presence of seating functions between manufacturers. CONCLUSIONS The differences found in the number of repairs reported by survey respondents based on PWC manufacturer and the increases in repairs over time require further evaluation.

Dynamic stiffness and transmissibility of commercially available wheelchair cushions using a laboratory test method.

Evidence suggests that wheelchair (WC) users are exposed to unhealthy levels of vibration during WC use. Health risks associated with vibration exposure include vertebral disc degeneration and back pain, which may consequently decrease the function and independence of WC users. Some evidence suggests that the cushions used in WCs may amplify vibrations, although conclusive evidence has not been presented in the literature. This study evaluated and compared the transmissibility of commercially available WC cushions with two laboratory test methods: (1) direct measurement of transmissibility while human subjects propelled a WC over a road course with different cushions and (2) characterization of cushions with a material testing system (MTS) combined with mathematical models of the apparent mass of the human body. Results showed that although dynamic characterization of WC cushions is possible with an MTS, the results did not correlate well with the transmissibility obtained in the WC road course. Significant differences were found for transmissibility among the cushions tested, with the air-based cushions having lower transmissibility than the foam- or gel-based cushions.

Wayfinding and Navigation for People with Disabilities Using Social Navigation Networks

To achieve safe and independent mobility, people usually depend on published information, prior experience, the knowledge of others, and/or technology to navigate unfamiliar outdoor and indoor environments. Today, due to advances in various technologies, wayfinding and navigation systems and services are commonplace and are accessible on desktop, laptop, and mobile devices. However, despite their popularity and widespread use, current wayfinding and navigation solutions often fail to address the needs of people with disabilities (PWDs). We argue that these shortcomings are primarily due to the ubiquity of the compute-centric approach adopted in these systems and services, where they do not benefit from the experience-centric approach. We propose that following a hybrid approach of combining experiencecentric and compute-centric methods will overcome the shortcomings of current wayfinding and navigation solutions for PWDs.

Evaluation of lightweight wheelchairs using ANSI/RESNA testing standards

Lightweight wheelchairs are characterized by their low cost and limited range of adjustment. Our study evaluated three different folding lightweight wheelchair models using the American National Standards Institute/Rehabilitation Engineering Society of North America (ANSI/RESNA) standards to see whether quality had improved since the previous data were reported. On the basis of reports of increasing breakdown rates in the community, we hypothesized that the quality of these wheelchairs had declined. Seven of the nine wheelchairs tested failed to pass the multidrum test durability requirements. An average of 194,502 +/- 172,668 equivalent cycles was completed, which is similar to the previous test results and far below the 400,000 minimum required to pass the ANSI/RESNA requirements. This was also significantly worse than the test results for aluminum ultralight folding wheelchairs. Overall, our results uncovered some disturbing issues with these wheelchairs and suggest that manufacturers should put more effort into this category to improve quality. To improve the durability of lightweight wheelchairs, we suggested that stronger regulations be developed that require wheelchairs to be tested by independent and certified test laboratories. We also proposed a wheelchair rating system based on the National Highway Transportation Safety Administration vehicle crash ratings to assist clinicians and end users when comparing the durability of different wheelchairs.

Relationship between wheelchair durability and wheelchair type and years of test

Objective. To investigate the relationship between the durability of wheelchairs according to American National Standard for Wheechairs/Rehabilitation Engineering and Assistive Technology Society of North America (ANSI/RESNA) Wheelchair Standards and wheelchair type as well as year of test. Design. A retrospective study design with a sample of 246 wheelchairs that were tested in accordance with the ANSI/RESNA standards from 1992 to 2008 including four types of wheelchairs: manual wheelchair (MWC), electrical powered wheelchair (EPW), scooters and pushrim-activated power-assisted wheelchair (PAPAW). Unconditional binary logic regression analysis was chosen to evaluate the relationship between test results and test year as well as wheelchair type. Setting. Rehabilitation Engineering Research Center. Main Outcome Measures: Wheelchair durability test result (fatigue test: pass or fail) Results. There was no significant correlation between the year when tested and equivalent cycles. A significant relation was found between test results and wheelchair type (Wald score = 10.845, degree of freedom = 3, p = 0.013) with scooters having a significantly higher pass ratio than MWC (OR = 15.629, 95% CI = 2.026–120.579). EPW also had significantly higher pass ratio than MWC (OR = 1.953, 95% CI = 1.049–3.636). No significant difference on pass ratio was found between PAPAW and MWC. Conclusions. No significant improvements in wheelchair test results during the time frame from 1992 to 2008 were discovered. Wheelchair standard tests should be conducted to assure minimum quality of the wheelchairs and for improving the design of wheelchairs. Although the ANSI/RESNA wheelchair durability test procedures have remained consistent, it does not appear that the introduction of new materials, designs and the availability of test data have improved wheelchair fatigue life.