Search

The design of the mobility enhancement robotic wheelchair (MEBot) was based on input from electric powered wheelchair (EPW) users regarding the conditions they encounter when driving in both indoor and outdoor environments that may affect their safety and result in them becoming immobilized, tipping over, or falling out of their wheelchair. Phase I involved conducting a participatory design study to understand the conditions and barriers EPW users found to be difficult to drive in/over. Phase II consisted of creating a computer-aided design (CAD) prototype EPW to provide indoor and outdoor mobility that addressed these conditions with advanced applications. Phase III involved demonstrating the advanced applications and gathering feedback from end users about the likelihood they would use the advanced applications. The CAD prototype incorporated advanced applications, including self-leveling, curb climbing, and traction control, that addressed the challenging conditions and barriers discussed with EPW users (n = 31) during the participatory design study. Feedback of the CAD design and applications in phase III from end users (n = 12) showed a majority would use self-leveling (83%), traction control (83%), and curb climbing (75%). The overall design of MEBot received positive feedback from EPW users. However, these opinions will need to be reevaluated through user trials as the design advances.

Physical activity monitors are increasingly used to help the general population lead a healthy lifestyle by keeping track of their daily physical activity (PA) and energy expenditure (EE). However, none of the commercially available activity monitors can accurately estimate PA and EE in people who use wheelchairs as their primary means of mobility. Researchers have recently developed custom EE prediction models for manual wheelchair users (MWUs) with spinal cord injuries (SCIs) based on a commercial activity monitor--the SenseWear armband. This study evaluated the performance of two custom EE prediction models, including a general model and a set of activity-specific models among 45 MWUs with SCI. The estimated EE was obtained by using the two custom models and the default manufacturer's model, and it was compared with the gold standard measured by the K4b2 portable metabolic cart. The general, activity-specific, and default models had a mean signed percent error (mean +/- standard deviation) of -2.8 +/- 26.1%, -4.8 +/- 25.4%, and -39.6 +/- 37.8%, respectively. The intraclass correlation coefficient was 0.86 (95% confidence interval [CI] = 0.82 to 0.89) for the general model, 0.83 (95% CI = 0.79 to 0.87) for the activity-specific model, and 0.62 (95% CI = 0.16 to 0.81) for the default model. The custom models for the SenseWear armband significantly improved the EE estimation accuracy for MWUs with SCI.

Upper-limb fatigue is a common problem that may restrict people with multiple sclerosis (MS) from using their electric powered wheelchair effectively and for a long period of time. The objective of this research is to evaluate whether participants with MS can drive better using a variable compliance joystick (VCJ) and customizable algorithms than with a conventional wheelchair joystick. Eleven participants were randomly assigned to one of two groups. The groups used either the VCJ in compliant or noncompliant isometric mode and a standard algorithm, personally fitted algorithm, or personally fitted algorithm with fatigue adaptation running in the background in order to complete virtual wheelchair driving tasks. Participants with MS showed better driving performance metrics while using the customized algorithms than while using the standard algorithm with the VCJ. Fatigue adaptation algorithms are especially beneficial in improving overall task performance while using the VCJ in isometric mode. The VCJ, along with the personally fitted algorithms and fatigue adaptation algorithms, has the potential to be an effective input interface for wheelchairs.

The ability of people with disabilities to live in their homes and communities with maximal independence often hinges, at least in part, on their ability to transfer or be transferred by an assistant. Because of limited resources and the expense of personal care, robotic transfer assistance devices will likely be in great demand. An easy-to-use system for assisting with transfers, attachable to electrical powered wheelchairs (EPWs) and readily transportable, could have a significant positive effect on the quality of life of people with disabilities. We investigated the stability of our newly developed Strong Arm, which is attached and integrated with an EPW to assist with transfers. The stability of the system was analyzed and verified by experiments applying different loads and using different system configurations. The model predicted the distributions of the system's center of mass very well compared with the experimental results. When real transfers were conducted with 50 and 75 kg loads and an 83.25 kg dummy, the current Strong Arm could transfer all weights safely without tip-over. Our modeling accurately predicts the stability of the system and is suitable for developing better control algorithms to enhance the safety of the device.

Acute mountain sickness (AMS) is a symptom complex noticed commonly among high altitude travelers. The occurrence of AMS depends on multiple factors that have been studied extensively. However, AMS in individuals with neurological impairments has not been considered in detail. A total of 168 subjects, including active controls, inactive controls, and those with spinal cord injury (SCI), multiple sclerosis, and traumatic brain injury (TBI), were studied at the National Veterans Winter Sports Clinic in Snowmass, Colorado, from 2007 to 2009 for the occurrence of AMS. Lake Louise Score was used to quantify symptoms. A higher than anticipated occurrence of AMS (42.85%) among the study population was noted, with significantly higher Lake Louis Scores among athletes with neurological impairments. Disability group, prior history of AMS, and prior occurrence of headache at high altitude could be used as predictors for the development of AMS symptoms. More research is warranted specifically targeting the interaction between factors affecting AMS and the pathophysiology of neurological impairments like SCI and TBI to further our understanding about prophylactic medications and treatments for AMS, especially because many military personnel with neurological impairments continue on Active Duty.

To date, only one research study has evaluated how scooters respond to static and dynamic stability. However, no other studies have evaluated how scooters respond to adverse conditions and how they perform in all standard tests. A selection of 12 three-wheeled scooters was tested according to American National Standards Institute/Rehabilitation Engineering and Assistive Technology Society of North America (ANSI/ RESNA) wheelchair standards. Scooter models included the Victory, Gogo, Golden Companion (GC) I, and GC II. Victory and GC II were the most stable scooters. The Gogo scooters were the least dynamically stable. Five scooters (3 Gogo, 1 GC I, 1 GC II) failed the environmental condition tests. All GC I and II scooters failed parts of the power and control system tests. All scooters passed static and impact tests; however, all Gogo scooters and one GC II scooter had structural or motor failure during durability tests. The scooter models' survival life ranged from 62,512 to 1,178,230 cycles out of the 400,000 needed to pass the test. Tiller failures (typically tiller tube snapping) occurred with an average of 1,483 N force applied to the tiller structure. Our results indicate that these commercially available devices may not meet ANSI/RESNA standards. In addition, the tiller test should be conducted with scooters to further ensure their safety and durability and should use a test dummy with weight capacity according to the mobility device capacity.

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.

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.

This study determined the driving characteristics of wheelchair users during power wheelchair soccer games. Data for this study were collected at the 28th and 29th National Veterans Wheelchair Games. Nineteen veterans who were 18 years or older and power wheelchair soccer players completed a brief demographic survey and provided information about their power wheelchairs. A customized data-logging device was placed on each participant's wheelchair before power soccer game participation. The data logger was removed at the end of the final game for each participant. The average distance traveled during the games was 899.5 +/- 592.5 m, and the average maximum continuous distance traveled was 256.0 +/- 209.4 m. The average wheelchair speed was 0.8 +/- 0.2 m/s, and the average duration of driving time was 17.6 +/- 8.3 min. Average proportion of time spent at a speed >1 m/s was 30.7% +/- 33.8%, between 0.5 and 1 m/s was 16.2% +/- 34.4%, and <0.5 m/s was 21.4% +/- 24.3%. The information from this descriptive study provides insight for future research in the field of adapted sports for people with high levels of impairments who use power wheelchairs for their mobility.

This study describes a new custom measurement system designed to investigate the biomechanics of sitting-pivot wheelchair transfers and assesses the reliability of selected biomechanical variables. Variables assessed include horizontal and vertical reaction forces underneath both hands and three-dimensional trunk, shoulder, and elbow range of motion. We examined the reliability of these measures between 5 consecutive transfer trials for 5 subjects with spinal cord injury and 12 nondisabled subjects while they performed a self-selected sitting pivot transfer from a wheelchair to a level bench. A majority of the biomechanical variables demonstrated moderate to excellent reliability (r > 0.6). The transfer measurement system recorded reliable and valid biomechanical data for future studies of sitting-pivot wheelchair transfers.We recommend a minimum of five transfer trials to obtain a reliable measure of transfer technique for future studies.

This study determined and compared wheelchair mobility patterns for older adults during an organized sporting event and within their community. In July 2008, 39 veterans participating in the 28th National Veterans Wheelchair Games (Omaha, Nebraska) completed the study. Of these, 26 were manual wheelchair and 13 were power wheelchair users. We collected wheelchair-related mobility data using wheelchair data-logging devices. Participants were significantly more active using manual wheelchairs during the games than when using their wheelchairs in their homes in terms of distance traveled (4,466.2 vs 1,367.4 m, p < 0.001) and average speed of propulsion (0.76 vs 0.64 m/s, p < 0.001). The trend was the same for power wheelchair users, with respect to distance (7,306.2 vs 3,450.5 m, p = 0.004) and average speed (0.9 vs 0.7 m/s, p = 0.002). This study demonstrates an objective method of evaluating wheelchair use in community-dwelling older adults.

Returning wounded veterans and servicemembers to their highest level of function following traumatic injury is a priority of the Departments of Defense and Veterans Affairs. We surveyed 245 veterans from the Vietnam war and 226 servicemembers and veterans from Operation Iraqi Freedom/Operation Enduring Freedom (OIF/OEF) conflicts with at least one major traumatic lower-limb loss to determine their use of mobility assistive technology (AT) and patterns of limb abandonment. Prosthetic device use without wheelchair use is found in 50.5% of Vietnam and 42.8% of OIF/OEF groups. Prostheses and supplementary wheelchairs are used by Vietnam (32%) and OIF/OEF (53%) groups (p < 0.01). Exclusive wheelchair use is more frequent in the Vietnam group (18%) than in the OIF/OEF group (4.0%, p < 0.01). In Vietnam participants, multivariate analysis found that multiple-limb loss (adjusted odds ratio [AOR] = 14.5; 95% confidence interval [CI] 5.5-38.5), bilateral lower-limb loss (AOR = 12.7; 95% CI 6.2-26.1), and number of comorbidities (AOR = 1.3; 95% CI 1.2-1.5) are associated with increased likelihood of wheelchair use. In OIF/OEF participants, bilateral lower-limb loss (AOR = 29.8; 95% CI 11.0-80.7), multiple-limb loss (AOR = 16.3; 95% CI 3.1-85.3), cumulative trauma disorder (AOR = 2.4; 95% CI 1.2-4.9), and number of combat injuries (AOR = 1.4; 95% CI 1.2-1.7) are associated with wheelchair use. Combined use of different types of mobility ATs promotes improved rehabilitation and ability to function.

Rehabilitation goals following major combat-associated limb loss in World War II and the Vietnam war focused on treatment of the injury and a return to civilian life. The goal for Operation Iraqi Freedom/Operation Enduring Freedom (OIF/OEF) servicemembers is to restore function to the greatest possible degree and, if they desire, return them to Active Duty, by providing them with extensive rehabilitation services and a variety of prosthetic devices. Our study determines the usefulness of these diverse types of prosthetic devices for restoring functional capability and documents prosthesis use and satisfaction. We compare servicemembers and veterans with major combat-associated unilateral lower-limb loss: 178 from the Vietnam war and 172 from OIF/OEF conflicts. Of survey participants with unilateral lower-limb loss, 84% of the Vietnam group and 94% of the OIF/OEF group currently use at least one prosthetic device. Reasons for rejection varied by type of device, but common reasons were pain, prosthesis too heavy, and poor fit. Abandonment is infrequent (11% Vietnam group, 4% OIF/OEF group). Future efforts should aim to improve prosthetic-device design, decrease pain, and improve quality of life for these veterans and servicemembers.

Multiple sclerosis (MS) causes a wide variety of neurological deficits, with ambulatory impairment the most obvious cause of disability. Within 10 to 15 years of disease onset, 80% of persons with MS experience gait problems due to muscle weakness or spasticity, fatigue, and loss of balance. To facilitate mobility, persons with MS frequently use mobility assistive technology (MAT), such as canes, crutches, walkers, wheelchairs, and scooters. We systematically reviewed the published literature on MAT use among persons with MS. We used electronic reference lists such as Ovid MEDLINE and PubMed to search the literature. We located 50 articles that met the initial criteria of providing good evidence of the types of MAT devices and their benefits for individuals with MS. A limited number of articles with higher levels of evidence was found regarding benefits of MAT use specifically for persons with MS. Evidence-based literature provides the basis for the strongest method of measurable clinical performance; therefore, having a strong research study design is vital to the justification of MAT prescription and reimbursement decisions. However, a paucity of studies with higher levels of evidence-based practice exists.

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.

We determined the demographic, health, functional, and satisfaction factors related to lower-limb prosthesis or wheelchair use among veterans with lower-limb amputation. Forty-two veterans were recruited from the 20th National Disabled Veterans Winter Sports Clinic and the 26th National Veterans Wheelchair Games. Participants were at least 18 years of age, had a lower-limb amputation, and were either prosthesis or wheelchair users. Level of amputation was the most significant health-related characteristic determining the veterans' use of a prosthesis versus a wheelchair (p = 0.02). Veterans who had a higher level of amputation and used a prosthesis reported significantly greater difficulty navigating a ramp (p = 0.03), getting in and out of cars and buses (p = 0.03), carrying 10 lb of groceries (p = 0.02), and participating in sports and leisure activities (p = 0.03). The parameter "satisfaction related to prosthesis" did not determine selection of mobility device type. The interaction of demographics, health-related characteristics, and mobility device characteristics affects functional performance and influences the use of prostheses, wheelchairs, or both in persons with lower-limb amputation. Long-term outcome assessments may help determine factors associated with either transition from one device to another or combined use of the devices over time.

This study's main objective was to determine if upper-limb (UL) muscular demand was reduced when individuals with a spinal cord injury (SCI) performed a sitting pivot transfer (SPT) in the preferred direction compared with that in a nonpreferred direction. Fourteen individuals (mean +/- standard deviation age 47.0 +/- 8.3 yr, height 1.80 +/- 0.08 m, and weight 75.3 +/- 11.3 kg) with SCI levels ranging from the sixth cervical to first sacral vertebra levels volunteered to participate in this study during the 2008 National Disabled Veterans Winter Sports Clinic. Surface electromyography (EMG) was used to record activity of the biceps, triceps, deltoid, pectoralis major, trapezius, and latissimus dorsi bilaterally during SPTs. These transfers were performed in each of the preferred and nonpreferred directions from the individuals' wheelchairs to a padded tub bench of even height. To quantify electromyographic muscular utilization ratio (MUR(EMG)), we normalized EMG data recorded during the transfer tasks to values obtained during static maximum voluntary contraction and then multiplied this ratio by 100 to obtain a percentage MUR(EMG) (%MUR(EMG)). The overall peak %MUR(EMG) and the area under the %MUR(EMG) curve were selected as primary outcome measures. Similar peak %MUR(EMGs) were found between the preferred and nonpreferred transfer directions for all muscles from which data were recorded (p = 0.053 to 0.961). The peak %MUR(EMGs) were also found to be similar between the leading and trailing ULs during the transfers in all muscles from which data were recorded (p = 0.125 to 0.838), except for the anterior deltoid, which was found to be solicited the most in the trailing UL (p = 0.008). Comparable areas under the %MUR(EMG) curves were calculated between the preferred and nonpreferred transfer directions for all muscles (p = 0.289 to 0.678) and between the leading and trailing ULs (p = 0.104 to 0.946). These results indicate that direction preference expressed by individuals with SCI when transferring between seats of even height is not explained by relative muscular demand differences.

People with disabilities such as multiple sclerosis and Parkinson's disease have difficulty operating conventional movement-sensing joysticks (MSJs) because of varying levels of tremor. We developed an isometric joystick (IJ) that has performed as well as a conventional MSJ when used by persons with upper-limb impairments in real and virtual wheelchair driving tasks. The Weighted-Frequency Fourier Linear Combiner (WFLC) filter has been used to cancel tremor effectively in microsurgery. In this study, we compared an MSJ, IJ, and IJ with the WFLC filter in individuals performing a virtual driving task. Although the WFLC filter did not improve driving performance in this study, the IJ without a filter yielded better results than the conventional MSJ and thus may be a potential alternative to the MSJ in minimizing the effects of tremor.

The Guido is a robotic walker that provides navigation and obstacle-avoidance assistance. Engineering tests have found that the device performs adequately and presents no hazard to the user. The performance of the Guido was compared with a low-tech mobility aid, the Assistive Mobility Device (AMD) developed at the Atlanta Department of Veterans Affairs Medical Center, in trials involving older adults with visual impairments. The purpose of this study was to determine whether the Guido could increase the safety and mobility of elderly visually impaired individuals in supervised care facilities. Subjects traversed an obstacle course with the Guido and the AMD. Completion time, obstacle/wall contacts, and reorientations were compared for both devices. No significant differences were found between the devices for any of the tests. The Guido did not perform better than the AMD during the trials. Revisions to the device as well as a change in subject requirements and testing protocol may produce different results.

Comfortable propulsion and support, light weight, and small dimensions are important features that help preserve upper-limb integrity of manual wheelchair users and improve accessibility. The titanium wheelchair is a product developed in response to these goals, but none of the test results of titanium wheelchairs had been disclosed before this study was performed. We hypothesized that these titanium wheelchairs would be in compliance with American National Standards Institute (ANSI)/Rehabilitation Engineering and Assistive Technology Society of North America (RESNA) standards. We tested 12 ultralight titanium rigid-frame wheelchairs (4 models) using ANSI/RESNA testing procedures and compared the test results with previously tested ultralight and lightweight aluminum wheelchairs. All wheelchairs passed the forward braking effectiveness test, but eight wheelchairs tipped backward before inclining to 7 degrees in the rearward braking effectiveness test. All wheelchairs passed the impact strength tests, but six wheelchairs failed in the static strength tests. Three wheelchairs successfully completed the fatigue tests, but the remaining wheelchairs failed prematurely. This group of titanium wheelchairs had less equivalent cycles and value than the ultralight aluminum wheelchairs that were tested in a previous study. The failure modes revealed important design issues of each model. Our results suggest that manufacturers may need to perform more careful analyses before commercializing new products.

Manual wheelchair users are subjected to whole-body vibrations (WBV) on a regular basis as they traverse obstacles and uneven surfaces. One way users could protect themselves from secondary injuries related to WBV is by using a suspension manual wheelchair. This study investigated the ability of suspension manual wheelchairs to reduce seat accelerations during curb descents of various heights (5, 10, and 15 cm). Sixteen manual wheelchairs (four suspension, four folding, four rigid, and four rigid titanium) were tested. Suspension wheelchairs transmitted significantly lower peak seat accelerations than folding wheelchairs during the 5 cm curb descents (p = 0.048) and significantly lower frequency-weighted peak seat accelerations during the 5 and 10 cm curb descents (p = 0.03 for both heights). However, when the suspension wheelchair Quickie XTR (Sunrise Medical; Carlsbad, California) was removed from the analysis, the suspension wheelchairs were not significantly different from the nonsuspension wheelchairs. When weight was considered, the suspension wheelchairs had significantly lower peak seat accelerations than the lighter rigid wheelchairs during 5 cm curb descents (p = 0.047). While suspension manual wheelchairs offer some reduction in WBV during curb descents, their limitations should be considered when a wheelchair is selected for everyday use.

A group of 158 service members who sustained major limb amputations during the global war on terrorism were surveyed on their satisfaction with the quality of care received from the Walter Reed Army Medical Center (WRAMC) Amputee Clinic from the time of their injury to their inpatient discharge. Of these participants, 96% were male, 77% were Caucasian, 89% were enlisted personnel, and 68% had sustained lower-limb amputations. WRAMC inpatient therapy, peer visitors, overall medical care, and pain management received particularly high satisfaction ratings. Age, race, rank, and level and side of amputation had little effect on overall satisfaction ratings. Significant differences, however, were found by location of injury (Iraq vs Afghanistan, Cuba, and Africa) regarding satisfaction with care received while in Europe and with the education process at WRAMC. Study findings strongly support the rehabilitation-based, integrative care approach designed by the U.S. military to care for service members with amputations.

Independent mobility is important, but some wheelchair users find operating existing manual or powered wheelchairs difficult or impossible. Challenges to safe, independent wheelchair use can result from various overlapping physical, perceptual, or cognitive symptoms of diagnoses such as spinal cord injury, cerebrovascular accident, multiple sclerosis, amyotrophic lateral sclerosis, and cerebral palsy. Persons with different symptom combinations can benefit from different types of assistance from a smart wheelchair and different wheelchair form factors. The sizes of these user populations have been estimated based on published estimates of the number of individuals with each of several diseases who (1) also need a wheeled mobility device and (2) have specific symptoms that could interfere with mobility device use.

Acute mountain sickness (AMS) is a frequent complication for military personnel, veterans, athletes, and travelers at high altitudes. Symptoms may occur in individuals with less cerebrospinal fluid volume and less ability to accommodate increased brain volume. No studies on AMS exist in individuals with neurological impairments. We studied 64 subjects, including active and sedentary controls and those with tetraplegia, paraplegia, multiple sclerosis, and traumatic brain injury at the 2007 National Veterans Winter Sports Clinic in Snowmass, Colorado. Subjects completed three Lake Louise Score surveys to quantify symptoms. We found a higher than expected occurrence of AMS overall (51.6%) but no differences among groups, and few participants sought treatment. Fatigue and weakness were common symptoms. High subject activity levels may explain these findings. More research is warranted on larger sample sizes and on preventative medications and treatments for AMS, especially since many military personnel with neurological impairments are returning to full active service.

This study examined the usage of powered seating functions, including tilt-in-space, backrest recline, and seat elevation, among a group of wheelchair users during their typical daily activities. Twelve individuals who used a power wheelchair with seating functions participated in the study. They drove their own wheelchair and used the seating functions as needed in their community environment for about 2 weeks while the seating function usage was recorded with a portable device. We found that subjects occupied their wheelchair for 11.8 +/- 3.4 hours a day (all data shown as mean +/- standard deviation). While occupying their wheelchairs, they accessed tilt-in-space, backrest recline, and seat elevation 19 +/- 14 times a day for 64.1% +/- 36.8%, 12 +/- 8 times for 76.0% +/- 29.8%, and 4 +/- 4 times for 22.5% +/- 34.9%, respectively. Subjects chose to stay in tilted and reclined positions in their wheelchair for 39.3% +/- 36.5% of their time each day. They spent little time in a fully upright position. Subjects changed their seating positions every 53.6 +/- 47.0 minutes. Time spent in positions of different seating pressures varied among subjects. The information collected could enhance clinical practice of wheelchair provision, resulting in better compliance with clinical instructions and appropriate use of seating functions among wheelchair users.

Individuals with multiple sclerosis (MS) report decreased satisfaction with their mobility devices compared with individuals with spinal cord injuries (SCIs). This study (1) investigated the demographic differences between veterans with MS (V-MS) and veterans with SCI (V-SCI) who were issued a wheelchair by the Veterans Health Administration (VHA) and (2) described differences in mobility device prescription. We merged two VHA databases to obtain demographic and wheelchair information for all V-MS and V-SCI in 2000 and 2001. Descriptive information for issued wheelchairs was available for 2,154 V-MS and V-SCI. We found that V-MS were significantly less likely to receive higher quality wheelchairs (manual or power) compared with V-SCI (p < 0.001). The disparity in VHA wheelchair prescription between these two groups indicates a need for further research regarding the assistive device prescription process in these populations.

During fiscal years 2000 and 2001, the Veterans Health Administration provided veterans with more than 131,000 wheelchairs and scooters at a cost of $109 million. This national study is the first to investigate Veterans Health Administration costs in providing wheelchairs and scooters and to compare regional prescription patterns. With a retrospective design, we used descriptive methods to analyze fiscal years 2000 and 2001 National Prosthetics Patient Database data (cleaned data set of 113,724 records). Wheelchairs were categorized by function, weight, and adjustability options for meeting individual needs (e.g., axle position, camber, position of wheels, tilt, and recline options). Results displayed a cost distribution that was negatively skewed by low-cost accessories coded as wheelchairs. Of the standard manual wheelchairs, 3.5% could be considered beyond the customary cost. Regionally, 71% to 86% of all wheelchairs provided were manual wheelchairs, 5% to 11% were power wheelchairs, and 5% to 20% were scooters. The considerable variation found in the types of wheelchairs and scooters provided across Veterans Integrated Service Networks may indicate a need for evidence-based prescription guidelines and clinician training in wheeled-mobility technologies.

Although engaging in an active lifestyle is beneficial for maintaining quality of life, a majority of wheelchair users are inactive. This study investigated the mobility characteristics and activity levels of manual wheelchair users in the residential setting and at the National Veterans Wheelchair Games (NVWG). Demographic factors that may have influenced activity in the home environment were also identified. Fifty-two manual wheelchair users completed a brief survey, and their activity was monitored with a custom data logger over a period of 13 or 20 days. We found that they traveled a mean +/- standard deviation of 2,457.0 +/- 1,195.7 m/d at a speed of 0.79 +/- 0.19 m/s for 8.3 +/- 3.3 h/d while using their primary wheelchair in the home environment. No significant differences in mobility characteristics or activity levels were found for level of spinal cord injury or disability. We also found that subjects traveled significantly farther and faster and were active for more hours during an average day at the NVWG than in the home environment (p < 0.001). We found that manual wheelchair users who were employed covered more distance, accumulated more minutes, and traveled a greater average maximum distance between consecutive stops than those who were unemployed. Results from this study provide a better understanding of the activity levels achieved by manual wheelchair users and insight into factors that may influence this activity.

A multisite collaborative study is being conducted on the association between propulsion biomechanics and upper-limb injuries. This substudy compared subject characteristics and pushrim kinetics across three sites and identified early on in the main study any differences that could affect interpretation of the findings or data pooling. A total of 42 manual wheelchair users with paraplegia (14 from each site) performed 0.9 m/s and 1.8 m/s steady state propulsion trials and an acceleration-brake-coastdown trial on a wheelchair dynamometer while propulsion forces and moment about the hub were measured with a SmartWheel. Significant differences between two sites were found in peak and average resultant force (p < 0.05), peak and average moment at the slower steady state speed (p < 0.005), and peak and average torque at the faster steady state speed (p = 0.06). Subjects at the site with significantly lower forces and torques had a slower deceleration rate during coastdown compared with the subjects at the other two sites (p < 0.001). These results imply that rolling resistance is lower at one of the sites and likely due to differences in dynamometer properties. A mechanical method was used to site-normalize the data and enable data pooling for future analyses.

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.

Little is known about the reasoning process clinicians use when prescribing wheeled mobility equipment (WME) or about the outcomes of this process, i.e., how many devices are prescribed, to whom, how often, and at what cost. This study characterized veterans who received WME from the Veterans Health Administration. We analyzed variance in wheelchair provision based on sex, race/ethnicity, diagnosis, and age. Three years of data from the National Prosthetics Patient Database and the National Patient Care Database were merged, yielding more than 77,000 observations per fiscal year. Logistic regression analysis revealed associations between WME provision and age, sex, and race/ethnicity, when analysis was controlled for diagnosis and number of comorbidities. Hispanics (odds ratio [OR] = 1.864), African Americans (OR = 1.360), and American Indians/Asians (OR = 1.585) were more likely than Caucasians to receive standard wheelchairs. Hispanics (OR = 0.4), African Americans (OR = 0.7), and American Indians/Asians (OR = 0.4) were less likely than Caucasians to receive scooters.

In this pilot study, we assessed wheelchair durability and its effect on user satisfaction. Specifically, we examined the characteristics of the participants' wheelchairs, the types of maintenance and repairs completed, and whether the participants' satisfaction was affected by problems with their wheelchairs. A convenience sample of 130 participants who used wheelchairs as their primary means of mobility was recruited. Participants completed a questionnaire about their wheelchairs, the maintenance and repair history, and their satisfaction levels. Results showed that 26% of the participants had completed a wheelchair repair in the past 6 months, 16% had completed general maintenance, and 27% had completed tire repairs. Neither hours of wheelchair use nor wheelchair age affected repair or maintenance frequency. Participants were generally satisfied with their wheelchairs. Better understanding of wheelchair maintenance and repair issues will guide improvements in wheelchair design and enhance the community participation of individuals who use wheelchairs.

The objective of this study was to conduct a kinetic analysis of manual wheelchair propulsion during start-up on select indoor and outdoor surfaces. Eleven manual wheelchairs were fitted with a SMART(Wheel) and their users were asked to push on a course consisting of high- and low-pile carpet, indoor tile, interlocking concrete pavers, smooth level concrete, grass, hardwood flooring, and a sidewalk with a 5-degree grade. Peak resultant force, wheel torque, mechanical effective force, and maximum resultant force rate of rise were analyzed during start-up for each surface and normalized relative to their steady-state values on the smooth level concrete. Additional variables included peak velocity, distance traveled, and number of strokes in the first 5 s of the trial. We compared biomechanical data between surfaces using repeated-measures mixed models and paired comparisons with a Bonferroni adjustment. Applied resultant force (p = 0.0154), wheel torque (p < 0.0001), and mechanical effective force (p = 0.0047) were significantly different between surfaces. The kinetic values for grass, interlocking pavers, and ramp ascent were typically higher compared with tile, wood, smooth level concrete, and high- and low-pile carpet. Users were found to travel shorter distances up the ramp and across grass (p < 0.0025) and had a higher stroke count on the ramp (p = 0.0124). While peak velocity was not statistically different, average velocity was slower for the ramp and grass, which indicates greater wheelchair/user deceleration between strokes. The differences noted between surfaces highlight the importance of evaluating wheelchair propulsion ability over a range of surfaces.

Over 50 percent of manual wheelchair users with spinal cord injury (SCI) are likely to develop upper-limb pain and injury. The majority of studies related to pain have implicated wheelchair propulsion as a cause. This paper draws from a large multisite trial and a long-standing research program to make specific recommendations related to wheelchair propulsion that may decrease the risk of upper-limb injury. The studies include over 60 subjects over 1 yr after a traumatic SCI below the second thoracic level. Specific aspects of the propulsive stroke that may relate to injury include cadence, magnitude of force, and the pattern of the hand during the nonpropulsive part of the stroke. Lower peak forces, slower cadence, and a circular propulsive stroke in which the hand falls below the pushrim during recovery may help prevent injury. In addition, wheelchair users should use the lightest weight adjustable wheelchair possible. Future work should include interventional trials and larger studies that allow for more complex statistical models that can further detail the relationship between wheelchair propulsion, user characteristics, and upper-limb injuries.

A walker that could help navigate and avoid collisions with obstacles could help reduce health costs and increase the quality of care and independence of thousands of people. This study evaluated the safety and performance of the Veterans Affairs Personal Adaptive Mobility Aid (VA-PAMAID). We performed engineering tests on the VA-PAMAID to determine safety factors, including stability, energy consumption, fatigue life, and sensor and control malfunctions. The VA-PAMAID traveled 10.9 km on a full charge and avoided obstacles while traveling at a speed of up to 1.2 m/s. No failures occurred during static stability, climatic, or fatigue testing. Some problems were encountered during obstacle climbing and sensor and control testing. The VA-PAMAID has good range, has adequate reaction time, and is structurally sound. Clinical trials are planned to compare the device to other low-technical adaptive mobility devices.

The primary objective of this study was to examine the kinematics and kinetics of the shoulder during wheelchair propulsion at a slow and moderate speed. Twenty-seven individuals with paraplegia propelled their wheelchairs at speeds of 0.9 m/s and 1.8 m/s while a motion analysis system captured movements of their upper limbs and SMART(Wheel)s simultaneously recorded their pushrim kinetics. Intraclass R correlation and Cronbach's coefficient alpha statistics revealed that all shoulder parameters were stable and consistent between strokes and speeds. The shoulder exhibited a greater range of motion, and forces and moments at the shoulder were 1.2 to 2.0 times greater (p < 0.05) during the 1.8 m/s speed trial. Peak posterior forces occurred near the end of the propulsion phase, and at the same time, the shoulder was maximally flexed and minimally abducted (p > 0.1). Shoulder positioning and the associated peak shoulder loads during propulsion may be important indicators for identifying manual wheelchair users at risk for developing shoulder pain and injury.

For individuals with a spinal cord injury or dysfunction (SCI/D), opportunities to exercise are limited and are usually not highly motivating experiences. Exercise programs or extracurricular activities may help increase or maintain the cardiovascular fitness level of individuals with SCI/D. The GAME(Wheels) system, an interface between a portable roller system and a computer, enables an individual to control a video game by propelling his or her wheelchair. The purpose of this study was to investigate whether the propulsive forces used during video play, both with and without the GAME(Wheels) system, were different. A secondary purpose was to examine differences in metabolic parameters during exercise under these two conditions. Ten manual wheelchair users exercised on the GAME(Wheels) system with and without controlling a video game. Physiological and kinetic data were collected six times during two exercise trials. Kinetic data were recorded with the SMART(Wheel) and used to investigate propulsion forces. No significant differences were found in the resultant force, rate of rise, or number of hand contacts with the pushrims. This study showed that propulsion pattern did not change significantly when wheelchair users exercised while playing a computer video game. Oxygen consumption, ventilation, and heart rate were significantly different (p < 0.05) between the two groups during the last three exercise intervals and cooldown. Playing a video game while exercising may help to motivate manual wheelchair users to exercise longer and regularly, something that was reported by this study's subjects; likewise, exercising while playing a video game may not be associated with higher pushrim forces and stroke frequencies.

Wheelchair locomotion is an important form of mobility for many individuals with spinal cord injury. However, manual wheelchair propulsion can lead to upper-limb pain and can be very inefficient. This has led investigators to apply biomechanics to the study of wheelchair use. The objectives of this study were (1) to determine the frequency content of the motion of both hands during two speeds of wheelchair propulsion, (2) to obtain the filter frequencies necessary to remove noise from wheelchair motion data, and (3) to provide signal-to-noise ratio data for wheelchair kinematics. The participants in this study were a random sample of manual wheelchair users with paraplegia caused by spinal cord injury. Subjects propelled their personal wheelchairs on a computer-controlled dynamometer at speeds of 0.9 m/s and 1.8 m/s. Motion data were collected at 60 Hz with the use of a commercial infrared marker-based system. The main outcome measures were arm motions and noise frequency spectra, filter cutoff frequencies, and signal-to-noise ratio. Our results indicate that there is no useful signal power above 6 Hz during manual wheelchair propulsion at the speeds that we analyzed. In many cases, there was no useful signal power above 4 Hz. This would indicate that the frequency content of manual wheelchair propulsion is similar to that of human gait. The mean signal-to-noise ratio varied from a high of 91 dB to a low of 21.8 dB. The signal-to-noise ratio was greatest in the x direction (along the line of progression) and lowest in the z direction (medial-lateral). Manual wheelchair propulsion kinematic data should be low-pass filtered at approximately 6 Hz for speeds at or below 1.8 m/s. The data presented in the archival literature appear to have been filtered at an appropriate frequency.

Shoulder pain and rotator cuff tears are highly prevalent in individuals with paraplegia (PP). The purpose of this study was to use magnetic resonance imaging (MRI), plain radiographs, questionnaires, and physical examination to gain insight into the prevalence of shoulder disorders in individuals with PP. A total of 28 individuals with PP was recruited (mean age=35; mean year from injury=11.5). Each subject completed a questionnaire designed to identify arm pain, had a standard physical examination focusing on the shoulder, and underwent imaging studies (radiographic and MRI). Nine of the thirty-two subjects (36 percent) experienced shoulder pain in the month prior to testing. The MRI studies documented only one rotator cuff tear. Five subjects showed osteolysis of the distal clavicle by plain radiographic study. In two subjects this was seen bilaterally. Although no relationship was seen between pain and imaging abnormalities, stepwise linear regressions found a statistically significant positive relationship between imaging abnormalities and body mass index (BMI) (radiographic: beta= 0.56, p<0.01; MRI: beta=0.52, p<0.01). This study found a low prevalence of rotator cuff tears and a high prevalence of distal clavicle osteolysis in a sample of relatively young individuals with PP. Although there was only one tear identified by MRI, a number of subclinical abnormalities were seen and found to correlate with BMI.

Little is known about how dynamic acceleration affects wheelchair-rider comfort. The current study was to test both the operation of an instrumented wheelchair by a wheelchair user over a Simulated Road Course (SRC) and the operation of the same instrumented wheelchair during normal daily activities (a field test) by test subjects. Sixteen subjects participated in the protocol. A SRC allowed collection of data from wheelchair users traversing obstacles similar to those experienced by a typical wheelchair user. The SRC consisted of eight obstacles fixed rigidly to a flat concrete surface. The field test began after the conclusion of the SRC test. Transfer functions were derived for all 16 subjects. It is clear from the results that for the SRC, the acceleration at the wheelchair frame exceeded the 8-h "fatigue-decreased performance boundary." A vertical acceleration resonant peak was evident for eight of the subjects. The average for these peaks, when present, was 8.1 Hz. This frequency is higher than the 4-6 Hz resonant peak presented in the literature for a seated human subject. This discrepancy could be due to different levels of trunk control between wheelchair users in this study and ambulatory subjects used in the literature. Subjects and their wheelchairs were exposed to a few, high-acceleration events rather than consistent, small-magnitude accelerations during the field test. This study indicates that vibration may be a contributing factor to fatigue among manual wheelchair users, which could lead to injury.

The inertia and resistance of a wheelchair dynamometer must be determined in order to compare the results of one study to another, independent of the type of device used. The purpose of this study was to describe and implement a dynamic calibration test for characterizing the electro-mechanical properties of a dynamometer. The inertia, the viscous friction, the kinetic friction, the motor back-electromotive force constant, and the motor constant were calculated using three different methods. The methodology based on a dynamic calibration test along with a nonlinear regression analysis produced the best results. The coefficient of determination comparing the dynamometer model output to the measured angular velocity and torque was 0.999 for a ramp input and 0.989 for a sinusoidal input. The inertia and resistance were determined for the rollers and the wheelchair wheels. The calculation of the electro-mechanical parameters allows for the complete description of the propulsive torque produced by an individual, given only the angular velocity and acceleration. The measurement of the electro-mechanical properties of the dynamometer as well as the wheelchair/human system provides the information necessary to simulate real-world conditions.

Changing seating posture can extend the amount of time a person can safely remain seated without damaging tissue or becoming fatigued. The Excelsior is an electrically powered wheelchair that utilizes sit-to-stand (STS) and sit-to-recline (STR) motions to aid in pressure relief. The motion of the wheelchair seating system must closely follow anatomical paths or ulcers may develop from the resulting shear forces. Displacement between the person and the wheelchair seating surface is one measure of these shear forces. The displacement between a Hybrid II 50th percentile anthropometric test dummy (ATD) and the seating surface of the Excelsior wheelchair was examined during STS and STR with two cushions, a Jay Active and a low-profile Roho cushion. The difference between the backrest and ATD back angles were 4.29 degrees +/- 2.13 degrees and 1.78 degrees +/- 1.73 degrees for the Roho and Jay cushions respectively during STS and 3.32 degrees +/- 4.21 degrees and 10.71 degrees +/- 6.20 degrees during STR. These were statistically significant at p<.05. During STS, shear displacement between the Hybrid II back and Excelsior backrest did not exceed 1.5 cm for either cushion. ATD thigh-to-seat displacements were 2.5 cm for the Jay and 3.0 cm for the Roho cushion. STR produced dummy thigh-to-seat displacements of 1.5 cm and 3.5 cm for the Jay and Roho cushions respectively. Shear displacement in the ATD back was about 3.5 cm for the Roho and 6 cm for the Jay. The latter displacement should be reduced; however, the other conditions are marginal or acceptable. Hysteresis was acceptable or better for all cushion/motion combinations, with the highest net displacement of about 2.5 cm.

Research is required to advance the understanding of issues related to the effect of physical activity on health and disease prevention among people with disabilities. This report is the result of a consensus process using selected experts in health and exercise. The purpose of the consensus conference was to identify research priorities for physical activity and health among people with disabilities. Priorities were established by 30 participants, who were selected by the principal investigators to achieve balance in the areas of engineering, epidemiology, medicine, nutrition, exercise physiology, and psychology. Experts summarized relevant data from their research and from comprehensive review of the scientific literature on the topic areas chosen for the conference. Public commentary was provided by participants in the 1996 Paralympic Congress. Panel members discussed openly all material presented to them in executive session. Commentary from open discussion periods were recorded and transcribed. Selected panelists prepared first drafts of the consensus statements for each research priority question. All of these drafts were distributed to the panelists and pertinent experts. The documents were edited by the drafting committee to obtain consensus. This research priority setting process revealed that greater emphasis must be placed on determining the risks and benefits of exercise among people with disabilities. Exercise must be studied from the perspective of disease prevention while mitigating risk for injury. Five areas were identified as focal points for future work: epidemiological studies; effects of nutrition on health and ability to exercise; cardiovascular and pulmonary health; children with disabilities; and accessibility and safety of exercise programs. As people with disabilities live longer, the need for addressing long-term health issues and risk for secondary disability must receive greater attention. As a consequence of the consensus process, specific recommendations for future research regarding the impact of exercise on the health and quality of life of persons with disabilities were defined.

Most of the 22 approved or developing ISO standards rely on a wheelchair test dummy, a specialized device described in ISO 7176-11. The purpose of this study was to develop a means for modifying the design of the ISO 7176-11 test dummy to be suitable for testing with higher masses. The changes are based upon published data for obese individuals. With these data, we derived equations for determining the distribution of the additional mass among the test dummy components, and the locations of the centers of mass. The results of this study provide guidelines for adding mass to the 100 kg wheelchair test dummy to accommodate testing of wheelchairs designed for obese individuals.

Wheelchair designs based upon loads applied quasi-statically during normal mobility use are apt to be inadequate to handle the increased level of dynamic crash forces that may be encountered when using the wheelchair as a motor vehicle seat. The purpose of this study was to characterize the integrity of wheelchair caster assemblies under simulated crash conditions. This study utilized dynamic drop (DD) testing, with loading levels and rates adjusted to match those found previously in sled impact testing and computer crash simulations. The results verify that current caster assembly designs may not be able to withstand forces associated with a crash. Five of seven evaluated caster assemblies failed when loaded to 8,007 N, or less, at loading rates seen in sled testing. DD testing used in this study is a valuable tool that can be used in the design of transport wheelchair components.