Ultralight Wheelchairs Research Articles

Computational Seated Pedestrian Impact Design of Experiments with Ultralight Wheelchair.

Pedestrians who use wheelchairs (seated pedestrians) report higher mortality rates than standing pedestrians in vehicle-to-pedestrian collisions but the cause of this mortality is poorly understood. This study investigated the cause of seated pedestrian serious injuries (AIS 3+) and the effect of various pre-collision variables using finite element (FE) simulations. An ultralight manual wheelchair model was developed and tested to meet ISO standards. The GHBMC 50th percentile male simplified occupant model and EuroNCAP family car (FCR) and sports utility vehicle (SUV) were used to simulate vehicle collisions. A full factorial design of experiments (n = 54) was run to explore the effect of pedestrian position relative to the vehicle bumper, pedestrian arm posture, and pedestrian orientation angle relative to the vehicle. The largest average injury risks were at the head (FCR: 0.48 SUV: 0.79) and brain (FCR: 0.42 SUV: 0.50). The abdomen (FCR: 0.20 SUV: 0.21), neck (FCR: 0.08 SUV: 0.14), and pelvis (FCR: 0.02 SUV: 0.02) reported smaller risks. 50/54 impacts reported no thorax injury risk, but 3 SUV impacts reported risks ≥ 0.99. Arm (gait) posture and pedestrian orientation angle had larger effects on most injury risks. The most dangerous arm posture examined was when the hand was off the wheelchair handrail after wheel propulsion and the two more dangerous orientations were when the pedestrian faced 90° and 110° away from the vehicle. Pedestrian position relative to the vehicle bumper played little role in injury outcomes. The findings of this study may inform future seated pedestrian safety testing procedures to narrow down the most concerning impact scenarios and design impact tests around them.

Design refinement and evaluation of a mobile manual standing wheelchair

Purpose There are no manually propelled wheelchairs on the market that are mobile in both seated and standing positions. In response to this product gap, our group formerly designed a mobile manual standing wheelchair (MMSW) and gathered stakeholder feedback. The purpose of this study was to refine the MMSW based on feedback, including weight and width reduction, and evaluate its performance. Materials and methods The MMSW was subjected to ANSI/RESNA stability testing, and three male participants completed a subset of the wheelchair skills test, including a 100-m roll test in the MMSW (seated and standing) and in their ultralight wheelchair. Results The MMSW met ANSI/RESNA stability safety standards. During the 100-m roll test, participants reached speeds with the MMSW in both the standing and sitting postures similar or greater than those typical of moving in the home environment (1.11 m/s seated; 0.79 m/s standing). Mobility speeds in the MMSW in the standing position were about three times faster than average walking speeds in exoskeletons (0.26 m/s exoskeletons). With the addition of chain drive bracing to the MMSW, one user was able to reach speeds in the standing position similar to average neurotypical walking speeds indicating the possibility for wheelchair users to be able to move in pace with family and friends. Conclusion All participants expressed interest in the MMSW to facilitate improved quality of life. Further work is needed to test the utility of the MMSW in home and community settings, and its potential effects on standing time and health outcomes. Implications for rehabilitation Manual standing wheelchairs with standing mobility may increase functional utility and length of standing time for manual wheelchair users Increased standing time may lead to several health benefits for manual wheelchair users

Comparing the performance of ultralight folding manual wheelchairs using standardized tests

Objective To evaluate ultralight folding manual wheelchairs (UFMWs) in order to produce comparative data on their strength, durability, stability and cost–benefit, and to determine progress of wheelchairs by comparing these results to results of past studies. Design Engineering testing using American National Standards Institute (ANSI) and Rehabilitation Engineering and Assistive Technology Society of North America (RESNA) standards. Setting Laboratory testing of UFMW stability, and static, impact and fatigue strength performance with three devices using ANSI/RESNA standardized tests. Participants The three wheelchair models were the TiLite Aero X (Permobil, Lebanon, TN), Sunrise Medical Quickie 2 (Fresno, CA) and Ki Mobility Catalyst 5 (Stevens Point, WI). Interventions ANSI/RESNA standardized tests. Main outcome measures Mass and critical measurements, static stability, static strength, impact strength, fatigue strength and cost analysis. Results The ultralight folding wheelchairs continued to outperform their lightweight and rigid framed counterparts. According to these data, the quality of ultralight wheelchairs has not declined over the past 10 years. The Ki Catalyst did not pass strength and durability testing, while the TiLite Aero X and Sunrise Medical Quickie 2 surpassed these tests. Conclusions This result exemplifies the need for ongoing research to identify whether wheelchairs satisfy ANSI/RESNA testing requirements and highlights the importance of creating a resource data set. This is particularly important when numerous other wheelchairs fail to meet minimum ANSI/RESNA requirements. Implications for Rehabilitation Folding frame wheelchairs offer benefits such as transportability and convenience that may benefit certain wheelchair users, assuming their durability is sufficient and they provide similar benefits vs. other wheelchair construction. Previous studies have shown that folding wheelchairs perform meet the minimum requirements of standardized testing, and it is important to see if durability has increased, decreased or remained the same over the years. Other wheelchair types have remained stagnant with respect to durability and are less likely to meet the minimum durability requirements. Durable devices will improve a wheelchair user’s quality of life by reducing downtime while waiting for repairs, and also reduce the likelihood of injury due to component failure.

Exploring the lived experience of people using ultralight wheelchairs with on-the-fly adjustable seating function

Introduction: Manual wheelchairs with spontaneous, user-initiated seating adjustability allow users to independently adjust both rear seat height and backrest angle on-the-fly to optimize positioning for various activities throughout the day.Purpose: This study aimed to examine the lived experience of users of wheelchairs with user-initiated seating adjustability and investigate the impact of this functionality in their day-to-day lives.Methods: This exploratory study involved eight participants who used manual wheelchairs with spontaneous, user-initiated adjustability. Participants engaged in semi-structured qualitative interviews, during which they were asked general open-ended questions about a typical day using their wheelchair, as well as specific questions addressing day-to-day usage, activity participation, and unique seating applications and situations where adjustments were used.Results: Our analysis identified three primary themes: (1) “New Angles on Function and Participation” revealed the impact adjustments had on physical function and participation; (2) “Comfort to Reach New Heights” described experiences related to positioning for comfort, and comments related to convenience and general usability; and (3) “Elevating Health and Social Standing” identified perceived effects of the wheelchair on user health and psychosocial parameters such as social interactions and self-esteem.Conclusions: Our study indicates that adjustable seating can have a significant impact on ultralight wheelchair users. Results may help with prescription of this class of wheelchair, and may also provide potential users and therapists some insight into the range of applications and benefits of on-the-fly adjustment features.Implications for rehabilitationFunctional ability can be improved through the use of on-the-fly adjustable seating functions, leading to heightened participation at home and in the community.Users of wheelchairs with adjustable seating experience psychosocial benefits including increased social interaction and social inclusion.Clinicians and consumers may want to consider the functions that are impacted by adjustable seating as a method of improving reach, transfers, comfort and social interactions of manual wheelchair users.

Comparison of carbon fibre and aluminium materials in the construction of ultralight wheelchairs

Carbon fibre-reinforced polymers have been used in the sporting goods industry for decades, and wheelchairs have incorporated the material since the late 1980s. There is no independently collected data available on carbon fibre-reinforced polymer wheelchairs’ performance on the ANSI/RESNA testing standards, however. This study evaluated three full carbon fibre wheelchair specimens to determine their performance versus similar wheelchairs. Testing determined that while the frames survived more testing cycles than any other wheelchair, the casters and rear tires failed similarly to other devices. Overall, due to the purchase cost, the cost benefit of the tested wheelchair model was similar to aluminium wheelchairs. Implications for rehabilitation Carbon fibre wheelchair construction is a viable alternative to aluminium, titanium, or steel construction, and decreasing costs will continue to improve the benefits of carbon fibre over these models Carbon fibre wheelchair found to be more durable than aluminium models, but are also much more expensive. The additional cost may be justified for some users that need the increased durability, however Increased durability will reduce the number of repairs and warranty claims, potentially reducing the burden on a wheelchair user, and also improving their ability to travel and participate in their community The low weight of carbon fibre wheelchairs may increase the mobility of some users by allowing them to transfer more easily into and out of vehicles and manoeuvre throughout the environment

End user evaluation of a Kneeling Wheelchair with “on the fly” adjustable seating functions

A “kneeling” ultralight wheelchair prototype has been developed that allows users to adjust seat position “on the fly” for different activities throughout the day. The wheelchair includes independent adjustment functions for rear seat height, front seat height (“kneeling”) and backrest angle. Aim: This work aimed to gather feedback about the wheelchair’s functionality and performance through end user evaluation trials. Methods: Eight manual wheelchair users evaluated the prototype Kneeling Wheelchair for a range of activities. User perspectives on parameters such as usability, comfort, stability and effectiveness were obtained through both open-ended and Likert-scale rating questions. Results: Results indicate several potential benefits of the adjustment functions of the Kneeling Wheelchair. Rear seat height adjustment may facilitate a number of activities of daily living, as well as provide benefits for comfort and social interactions. Back rest adjustment may increase comfort and stability on slopes. Front seat height adjustment may be beneficial for transfers and conducting sustained low-to-the-ground activities. While benefits of this adjustment function were described by many participants, some struggled with usability of the kneeling mechanism and rated this function less favourably than the other two. Conclusion: The findings of this study will inform future iterations of the Kneeling Wheelchair design and may spur future developments in wheeled mobility. In the long-term, it is anticipated that novel wheelchair solutions, such as the one described in this paper, may support improved health, quality of life and community participation for people with mobility impairments.Implications for rehabilitationWheelchairs that allow users to easily adjust seat and backrest position “on the fly” to better suit different tasks throughout the day may provide benefits such as facilitating activities of daily living.A front seat height adjustment feature on a new wheelchair prototype may be beneficial for transfers and conducting sustained low-to-the ground activities.End user evaluations can provide valuable insight to direct future design modifications and innovation.

Comparison of High-Strength Aluminum Ultralight Wheelchairs Using ANSI/RESNA Testing Standards

Background: The use of ultralight manual wheelchairs has been shown to benefit wheelchair users when compared to other types. New aluminum alloy frame materials coming to the market have not been independently evaluated for durability and cost benefit. Methods: Three 70XX aluminum ultralight wheelchair models were tested and compared based on dimensions, stability, and durability using the ANSI/RESNA standards. The results were also compared to previous manual wheelchair studies. Results: This study found that there were no significant cost benefit or durability differences between the wheelchairs tested and previous aluminum or titanium ultralight rigid models. Additionally, 5 of the 9 wheelchairs tested failed to meet the minimum ANSI/RESNA requirements for durability. Conclusion: These results are similar to results from previous rigid ultralight wheelchair studies and indicate that the quality of wheelchairs of this type has not improved and better requirements are necessary for wheelchairs marketed in the United States.

Characterizing the community use of an ultralight wheelchair with "on the fly" adjustable seating functions: A pilot study.

An ultralight manual wheelchair that allows users to independently adjust rear seat height and backrest angle during normal everyday usage was recently commercialized. Prior research has been performed on wheelchair tilt, recline, and seat elevation use in the community, however no such research has been done on this new class of manual ultralight wheelchair with “on the fly” adjustments. The objective of this pilot study was to investigate and characterize the use of the two adjustable seating functions available on the Elevation™ ultralight dynamic wheelchair during its use in the community. Eight participants had data loggers installed onto their own wheelchair for seven days to measure rear seat height, backrest angle position, occupied sitting time, and distance traveled. Analysis of rear seat height and backrest adjustment data revealed considerable variability in the frequency of use and positions used by participants. There was a wide spread of mean daily rear seat heights among participants, from 34.1 cm to 46.7 cm. Two sub-groups of users were further identified: those who sat habitually at a single typical rear seat height, and those who varied their rear seat height more continuously. Findings also showed that participants used the rear seat height adjustment feature significantly more often than the backrest adjustment feature. This obvious contrast in feature use may indicate that new users of this class of wheelchair may benefit from specific training. While the small sample size and exploratory nature of this study limit the generalizability of our results, our findings offer a first look at how active wheelchairs users are using a new class of ultralight wheelchair with “on the fly” seating adjustments in their communities. Further studies are recommended to better understand the impact of dynamic seating and positioning on activity, participation and quality of life.

Wheelchair use in ultra-lightweight wheelchair users

Purpose: The goal of this study was to describe how ultra-lightweight wheelchair users use their wheelchairs during everyday mobility.Method: We instrumented a convenience sample of 69 ultra-lightweight wheelchair users with a seat switch to measure their occupancy, and an accelerometer on their wheel to measure distance wheeled, time spent wheeling and daily bouts of mobility.Results: On the median day, subjects wheeled 83 bouts and 1.4 km over 45 min. A typical bout of mobility was 8.3 m in length, lasting 20 s and occurring at a speed of 0.44 m/s. Fast (>1 m/s) and long (>2 min) bouts represented less than 4% of bouts and were more common among younger participants and those who were employed or a student.Conclusions: Highly functional manual wheelchair users present with a significant mobility disability, moving far less than their ambulating peers despite moving with similar mobility characteristics. The typical bout characteristics – short and slow bouts – are consistent with indoor mobility and transitions between functional activities. For wheelchair users, it highlights the importance of manoeuverability and the need for prescription and training to emphasize manoeuverability.Implications for RehabilitationMeasurement of wheelchair use, both how and how much, might provide unique insight to what equipment would be most appropriate for an individual.Participants who used an ultralight wheelchair presented with a significant mobility disability, wheeling only 1.7 km/day on average.Fast (>1 m/s) and long (>2 min) bouts are uncommon, representing less than 4% of bouts. Younger participants and those who were employed or a student were more likely to wheel one fast and long bout per day.Because wheelchair mobility was dominated by short, slow bouts, prescription and training need to emphasize maneuverability.

The effect of caster wheel diameter and mass distribution on drag forces in manual wheelchairs.

This study proposes a way to reduce energy losses in the form of rolling resistance friction during manual wheelchair propulsion by increasing the size of the front caster wheels and adjusting the weight distribution. Drag tests were conducted using a treadmill and a force transducer. Three different casters diameter (4 in., 5 in., and 6 in.) and six different mass distribution combinations (based on percentage of total weight on the caster wheels) were studied. A two-way analysis of variance test was performed to compare caster size and weight distribution contribution with drag force of an ultralight wheelchair. The 4 in. caster contributed significantly more drag, but only when weight was 40% or greater over the casters. Weight distribution contributed more to drag regardless of the casters used.

Development and pilot testing of a kneeling ultralight wheelchair design.

"Dynamic wheeled mobility" offers "on the fly" seating adjustments for wheelchair users such that various activities performed throughout the day can be matched by an appropriate seat position. While this has benefits for user participation and health, the added weight in existing dynamic wheelchairs may impact the user's ability to transport the frame, e.g. into cars. Other dynamic features to enable more participation avenues are also desirable. This paper outlines the development of a "kneeling" ultralight wheelchair design that offers dynamic wheeled mobility functionality at a weight that is comparable to many existing ultralight wheelchairs. In addition, the wheelchair's kneeling function allows a lowered seat position to facilitate low-to-the-ground tasks such as floor transfers and other activities where sustained low level reaching may be required (e.g. playing with children, changing a tire, etc.). This paper also describes the development and pilot testing of an end user evaluation protocol designed to validate the wheelchair's functionality and performance. Successful realization and commercialization of the technology would offer a novel product choice for people with mobility disabilities, and that may support daily activities, health, improved quality of life, and greater participation in the community.

Adaptive Sports Technology and Biomechanics: Wheelchairs

Wheelchair sports are an important tool in the rehabilitation of people with severe chronic disabilities and have been a driving force for innovation in technology and practice. In this paper, we will present an overview of the adaptive technology used in Paralympic sports with a special focus on wheeled technology and the impact of design on performance (defined as achieving the greatest level of athletic ability and minimizing the risk of injury). Many advances in manual wheelchairs trace their origins to wheelchair sports. Features of wheelchairs that were used for racing and basketball 25 or more years ago have become integral to the manual wheelchairs that people now use every day; moreover, the current components used on ultralight wheelchairs also have benefitted from technological advances developed for sports wheelchairs. For example, the wheels now used on chairs for daily mobility incorporate many of the components first developed for sports chairs. Also, advances in manufacturing and the availability of aerospace materials have driven current wheelchair design and manufacture. Basic principles of sports wheelchair design are universal across sports and include fit; minimizing weight while maintaining high stiffness; minimizing rolling resistance; and optimizing the sports-specific design of the chair. However, a well-designed and fitted wheelchair is not sufficient for optimal sports performance: the athlete must be well trained, skilled, and use effective biomechanics because wheelchair athletes face some unique biomechanical challenges.

地域連携による超軽量車椅子の開発

地域連携による超軽量車椅子の開発

Factors contributing to extended activity times during the provision of wheeled mobility devices

Purpose: A secondary analysis was performed on data from a recent time-motion study documenting the type and duration of activities performed during the provision of wheeled mobility and seating devices. The objective of this analysis was to report factors that were most associated with activities having extended durations. Method: Activities were categorized as occurring during the visit-preparation, pre-delivery, delivery or follow-up phases of equipment provision. Extended activities were defined as activities at or exceeding the 75th percentile, corresponding to activities exceeding 37.5 min. Logistic regression and Odd Ratio calculations were used to identify factors that were associated with extended encounters with clients. Results: Extended activities were more likely to be associated with Group 4 power chairs, ultra-lightweight wheelchairs and seating systems comprised of a combination of technologies, such as those with postural supports or using made-to measure or custom-molded techniques. Conclusions: Wheelchair and seating system type were more predictive of extended activities compared to diagnostic categories. This result leads us to posit that functional needs – rather than diagnosis – impacts the duration of client encounters and the complexity of the equipment prescribed to the user. The results also indicate that more complex equipment were more likely to require extended encounters than less complex devices in their respective groupings.Implications for RehabilitationThe provision of wheelchairs and seating systems include many types of activities including some which last for extended or lengthy periods of time.Complex equipment were more associated with extended activities compared to client diagnosis meaning that a person’s functional ability influences the complexity of the intervention more than diagnosis.Activities occurring prior to delivery, including assessment and wheelchair assembly, were twice as likely to last an extended time compared to other activities.The activities associated with ultralight weight manual wheelchairs were 8 times more likely to require lengthy activities compared to all other types of wheelchairs.

Guest Editorial: Wheelchair research progress, perspectives, and transformation

There is a growing and rich body of research and development being generated around the world. A simple search of PubMed using the search term wheelchair shows that 259 articles were published in the past year, 566 in the past 2 years, 1,315 in the past 5 years, and 2,241 over the past 10 years. If one narrows the search to the number of publications drops precipitously to 31 articles in the past year, 70 in the past 2 years, 156 in the past 5 years, and 265 in the last 10 years. The number of published articles drops even further if the search is specific to the design of new technologies. This simple investigation provides some insights worth examining. The output of research has risen over the past 10 years: there was a 17 percent increase in the number of total articles published in the last 5 years versus the previous 5 years, although there are natural annual fluctuations. Similarly, there has been about an 18 percent increase in the number of articles related to power wheelchairs, although the overall numbers are quite small. Most of the articles are related to usage and clinical assessment, with a few on training. Wheelchairs are an important modality for mobility, activity, and participation in life. For people with some forms of impairment (e.g., spinal cord injury [SCI]), wheelchairs are the primary means of mobility. Manual research seems to be fairly healthy even though many unanswered questions remain. Recent studies have indicated that there are challenges to obtaining high-quality manual wheelchairs. Liu et al. have shown that many ultralight wheelchairs are not compliant with Rehabilitation Engineering and Assistive Technology Society standards and fail prematurely [1]. This research is supported by a study of maintenance and repairs by McClure et al. showing that wheelchairs require frequent repairs and that those repairs start within the first few months of using a new chair [2]. More recently, Riggins et al. showed that there are still gaps in our knowledge about when to provide a wheelchair, to whom, and what training is necessary, even for people with SCI [3]. This study indicated that people with incomplete SCI, who focused on gait training, did not fare as well as their counterparts with complete or higher level lesions who received training in terms of community participation and quality of life. As a result of research conducted over the past 10 years, there is greater understanding of activity, service-delivery processes, manual skills training, and set-up of wheelchairs. There is a paucity of research into all aspects of power wheelchairs. This is somewhat surprising given the hundreds of thousands of people who use power wheelchairs, including scooters. Power-wheelchair users are also among the most vulnerable members of society in terms of ability to perform activities of daily living, community participation, and employment. Power-wheelchair users have also faced tremendous pressures from insurance providers to reduce costs. The challenges started when Medicare revised its reimbursement policy in 2007 and introduced new classifications for power wheelchairs that reduced the 42 procedural codes to 4 basic groups [4]. The groups are intended to be founded on performance and user needs. Unfortunately, one result of this process was to severely restrict access to the best wheelchairs, those in group 4, intended for active indoor and outdoor use. Many insurance companies have followed Medicare's lead and cover only power wheelchairs designed primarily for indoor use and light outdoor activities on well-conditioned surfaces. The Department of Veterans Affairs has bucked this trend since part of its mission is to promote independent living, return to employment, and full community participation. More research is needed to determine the long-term impact of these policy decisions on consumers and on power-wheelchair design. …

Lightweight and Ultralight Wheelchairs: Propulsion and Preferences of Two Young Children with Spina Bifida

This study compared the influence of two wheelchair styles, an ultralight rigid frame and a lightweight folding frame, on preference and propulsion in young children with spina bifida. Speed, distance, energy expenditure, and perceived exertion of two girls were studied in an A-B-A single subject design. Questionnaires were used after the three phases to obtain parent and child preference. Visual inspection of the data favored the ultralight wheelchair for all variables, except the first child's speed with classmates and perceived exertion. Parents and children indicated preference for the ultralight wheelchair on all questions but one by Child 1. Using two standard deviation band width (2SDBW) analyses, 12 of 16 comparisons between the phases differed significantly. 2SDBW comparison was not used in the other four phase comparisons because of autocorrelations. This study presents initial evidence supporting the use of ultralight rigid-framed wheelchairs by young children.

A comparison of functional mobility in standard vs. ultralight wheelchairs as measured by performance on a community obstacle course

Purpose: Appropriate wheelchair prescription requires maximizing user function while justifying cost. The purpose of this study was to investigate differences in a user's performance of mobility skills (on a community obstacle course) between an ultralight (UWC) and standard wheelchair (SWC). Subjects: Sixty healthy adults (mean = 28.3 years) without wheelchair experience performed one course trial. Methods: Participants were randomly assigned to an UWC or a SWC. Researchers recorded time for completion, Rating of Perceived Exertion (RPE), and number, location, and types of errors committed. Errors included contact of WC and any obstacle, front casters leaving the ground, or loss of directional control (veering). Results: A MANOVA of the data (p < 0.05) showed a significant difference in numbers of contact errors (higher in the SWC) and castor errors (higher in the UWC) between the two wheelchairs. Number of veering errors, time to complete, and RPE were not significantly different. Conclusions: Differences in wheelchair design can lead to differences in a user's performance of functional mobility skills. Choice of wheelchair may affect a user's ability to be independent in a community setting.

Seat and footrest shocks and vibrations in manual wheelchairs with and without suspension

Cooper RA, Wolf E, Fitzgerald SG, Boninger ML, Ulerich R, Ammer WA. Seat and footrest shocks and vibrations in manual wheelchairs with and without suspension. Arch Phys Med Rehabil 2003;84:96-102. Objective: To examine differences in the shock and vibration transmitted to an occupant of a manual wheelchair with and without suspension caster forks and with and without rear-suspension systems. Design: Repeated-measures engineering testing. Setting: Rehabilitation engineering center with a wheelchair standards test laboratory. Specimens: Six manual wheelchairs. Interventions: An American National Standards Institute/Rehabilitation Engineering and Assistive Technology Society of North America wheelchair test dummy and a Hybrid III test dummy were used to test shock and vibration transmission in wheelchairs equipped with original equipment manufacturer (OEM) caster forks and suspension caster forks. Ultralight wheelchairs, half of which had factory-equipped rear-suspension systems, were tested. Testing was conducted on a double-drum wheelchair test machine. Main Outcome Measures: Shocks were examined by using peak acceleration and the frequency at which peak acceleration occurs for the seat and footrest. Vibration was characterized by the acceleration power per octave for the seat and footrest. Results: Significant differences were found in the peak accelerations at the seat ( P=.0004) and footrest ( P=.0007) between the wheelchairs with the OEM caster forks and those with the suspension casters. The wheelchairs with suspension had significantly different frequencies at which the peak accelerations occurred for both the seat ( P=.01) and footrest ( P=.0001). The wheelchairs with suspension caster forks had a lower total power per octave than the wheelchairs with the OEM caster forks. For the footrest vibrations, significant differences were found between the types of caster forks for all octaves except those associated with frequencies more than 78.75Hz. There were significant differences for wheelchairs with and without rear suspension for total power per octave of seat vibrations in the octaves between 7.81 and 9.84Hz ( P=.01) and 12.40 and 15.63Hz ( P=.008). Conclusions: Suspension caster forks reduce the shock and vibration exposure to the user of a manual wheelchair. Rear-suspension systems reduce some of the factors related to shock and vibration exposure, but they are not clearly superior to traditional designs. [copy ] 2003 by the American Congress of Rehabilitation Medicine and the American Academy of Physical Medicine and Rehabilitation .

Comparison of fatigue life for 3 types of manual wheelchairs

Fitzgerald SG, Cooper RA, Boninger ML, Rentschler AJ. Comparison of fatigue life for 3 types of manual wheelchairs. Arch Phys Med Rehabil 2001;82:1484-8. Objectives: To examine 3 types of manual wheelchairs—ultralight wheelchairs (UWs), lightweight wheelchairs (LWs), and depot wheelchairs (DWs)—and to compare the fatigue life between the wheelchair types. Design: A database of different manual wheelchairs tested according to the International Organization for Standardization (ISO). Fatigue life was determined by using standards that define methods accepted internationally using double-drum and curb-drop testing equipment. Setting: A rehabilitation engineering center. Specimens: Sixty-one manual wheelchairs: 25 DWs, 22 UWs, and 14 LWs. Main Outcome Measures: Wheelchairs were examined for differences in fatigue life based on equivalent cycles. Unique survival curves were fit and compared for each wheelchair type. Results: The UWs lasted the longest, with a mean of 309,362 equivalent cycles. The DWs faired the worst, with a mean of 117,210 equivalent cycles. The Kaplan-Meier survival curves were significantly different (p < .001), with the UWs having the longest fatigue life. Conclusion: Fatigue life for UWs is significantly greater (p < .05) than LWs and DWs, indicating wheelchairs differ in durability. © 2001 by the American Congress of Rehabilitation Medicine and the American Academy of Physical Medicine and Rehabilitation

User assessment of manual wheelchair ride comfort and ergonomics

DiGiovine MM, Cooper RA, Boninger ML, Lawrence BM, VanSickle DP, Rentschler AJ. User assessment of manual wheelchair ride comfort and ergonomics. Arch Phys Med Rehabil 2000;81:490-4. Objective: To examine wheelchair-user perceived ride comfort during propulsion and to compare the ride comfort of ultralight and lightweight manual wheelchairs. An ultralight wheelchair is defined as having a high degree of adjustability, whereas a lightweight wheelchair has minimal adjustability. Design and Participants: Repeated measures design of a sample of 30 community-dwelling manual wheelchair users evaluating 7 different manual wheelchairs over an activities of daily living course. Setting: A rehabilitation engineering center. Main Outcome Measures: Subject ratings of perceived ride comfort and basic ergonomics while propelling over the activities of daily living course. Ratings were recorded for each wheelchair on individual tasks and for the course overall. Results: The Invacare Action XT wheelchair was ranked best for both ride comfort and basic ergonomics. The ride-comfort scores (p <.05) and wheelchair ergonomics ratings (p <.05) for the ultralight wheelchair group were significantly different from those for lightweight wheelchair group. Conclusion: There are differences in perceived ride comfort and basic ergonomics between the designs of the wheelchairs (lightweight vs ultralight). Subjects perceived that ultralight wheelchairs were more comfortable and had better basic ergonomics than lightweight wheelchairs. © 2000 by the American Congress of Rehabilitation Medicine and the American Academy of Physical Medicine and Rehabilitation