Wheelchair propulsion biomechanics and wheelers' quality of life: an exploratory review

PURPOSE. To provide an overview of associations between wheelchair propulsion biomechanics for both everyday and racing wheelchairs, wheeling-related upper limb injuries, and quality of life of manual wheelchair users through a synthesis of the available information. METHODS. A search of publications was carried out in PubMed and SportsDiscus databases. Studies on wheelchair propulsion biomechanics, upper limb injuries associated with wheelchair propulsion and quality of life of wheelchair users were identified. Relevant articles cited in identified articles but not cited in PubMed or SportsDiscus were also included. RESULTS. Wheelchair sports participation has positive impact on quality of life and research in racing wheelchair biomechanics can indirectly promote the visibility of wheelchair sports. The impact of pushrim-activated power-assisted wheelchairs (a hybrid between manual and battery-powered wheelchairs) and geared manual wheels on wheelers' everyday life were discussed. CONCLUSIONS. The study of wheelchair propulsion biomechanics focuses on how a wheelchair user imparts power to the wheels to achieve mobility and the accumulated knowledge can help to improve wheelchair users' mobility, reduce physical stress associated with wheelchair propulsion, and as a result, enhance quality of life.     

Assessment of physiological performance and perception of pushing different wheelchairs on indoor modular units simulating a surface roughness often encountered in under-resourced settings

In under-resourced settings where motorized wheelchairs are rarely available, manual wheelchair users with limited upper-body strength and functionalities need to rely on assisting pushers for their mobility. Because traveling surfaces in under-resourced settings are often unpaved and rough, wheelchair pushers could experience high physiological loading. In order to evaluate pushers’ physiological loading and to improve wheelchair designs, we built indoor modular units that simulate rough surface conditions, and tested a hypothesis that pushing different wheelchairs would result in different physiological performances and pushers’ perception of difficulty on the simulated rough surface. Eighteen healthy subjects pushed two different types of pediatric wheelchairs (Moti-Go manufactured by Motivation, and KidChair by Hope Haven) fitted with a 50-kg dummy on the rough and smooth surfaces at self-selected speeds. Oxygen uptake, traveling distance for 6 minutes, and the rating of difficulty were obtained. The results supported our hypothesis, showing that pushing Moti-Go on the rough surface was physiologically less loading than KidChair, but on the smooth surface, the two wheelchairs did not differ significantly. These results indicate wheelchair designs to improve pushers’ performance in under-resourced settings should be evaluated on rough surfaces.     

Impact of Mass and Weight Distribution on Manual Wheelchair Propulsion Torque

Propulsion effort of manual wheelchairs, a major determinant of user mobility, is a function of human biomechanics and mechanical design. Human studies that investigate both variables simultaneously have resulted in largely inconsistent outcomes, motivating the implementation of a robotic propulsion system that characterizes the inherent mechanical performance of wheelchairs. This study investigates the impacts of mass and mass distribution on manual wheelchair propulsion by configuring an ultra-lightweight chair to two weights (12-kg and 17.6-kg) and two load distributions (70% and 55% on drive wheels). The propulsion torques of these four configurations were measured for a straight maneuver and a fixed-wheel turn, on both tile and carpet. Results indicated that increasing mass to 17.6-kg had the largest effect on straight acceleration, requiring 7.4% and 5.8% more torque on tile and carpet, respectively. Reducing the drive wheel load to 55% had the largest effect on steady-state straight motion and on both turning acceleration and steady-state turning; for tile and carpet, propulsion torque increased by 13.5% and 11.8%, 16.5% and 4.1%, 73% and 5.1%, respectively. These results demonstrate the robot’s high sensitivity, and support the clinical importance of evaluating effects of wheelchair mass and axle position on propulsion effort across maneuvers and surfaces.     

Wheelchair propulsion biomechanics and wheelers' quality of life: an exploratory review

Purpose.?To provide an overview of associations between wheelchair propulsion biomechanics for both everyday and racing wheelchairs, wheeling-related upper limb injuries, and quality of life of manual wheelchair users through a synthesis of the available information.

Methods.?A search of publications was carried out in PubMed and SportsDiscus databases. Studies on wheelchair propulsion biomechanics, upper limb injuries associated with wheelchair propulsion and quality of life of wheelchair users were identified. Relevant articles cited in identified articles but not cited in PubMed or SportsDiscus were also included.

Results.?Wheelchair sports participation has positive impact on quality of life and research in racing wheelchair biomechanics can indirectly promote the visibility of wheelchair sports. The impact of pushrim-activated power-assisted wheelchairs (a hybrid between manual and battery-powered wheelchairs) and geared manual wheels on wheelers' everyday life were discussed.

Conclusions.?The study of wheelchair propulsion biomechanics focuses on how a wheelchair user imparts power to the wheels to achieve mobility and the accumulated knowledge can help to improve wheelchair users’ mobility, reduce physical stress associated with wheelchair propulsion, and as a result, enhance quality of life.     

Assessment of wheelchair drag resistance using a coasting deceleration technique

OBJECTIVE: To apply a recently developed coasting deceleration method to measure rolling and aerodynamic resistances opposing wheelchair propulsion on a variety of different wheelchairs and wheel combinations and on two different ground surfaces. DESIGN: For each condition, 20-25 trials were performed across a speed range of approximately 70-300 m/min. The least-squares method was then used to arrive at values for the coefficient of rolling resistance (CR) and effective frontal area of the wheelchair and occupant. RESULTS: Wheelchair rolling resistance was found to be velocity dependent under some circumstances. CR values on linoleum differed among folding lightweight wheelchairs and when compared with a rigid ultralight and racing wheelchair. Changing rear wheels and tires on one wheelchair resulted in a 14% difference in CR. Carpet increased CR values by an average of 0.0118 over the values determined on linoleum. As expected, effective frontal area of the wheelchair and occupant values were lower for the racer than for the folding lightweight wheelchair. CONCLUSIONS: Wheelchair rolling resistance is not always independent of velocity, and CR on linoleum can vary among wheelchairs by as much as seven-fold, and carpet can more than double CR.     

Ergonomic analysis of wheelchair designs

Four types of wheelchair available in India were evaluated from physiological, anthropometric and biomechanical points of view. None of the wheelchairs had a seat designed to provide comfort to the majority of disabled users. The diameter of the castor wheels in one type of wheelchair was found to be more suitable for overcoming the more common obstacles in buildings and net oxygen cost of this type was found to be much lower than the others. Propulsion of all the wheelchairs consumed more than 50% of the VO_{2 max} of the disabled persons. The space allowed between the hand rim and the wheel was not adequate in any of the designs for comfortable and efficient propulsion. From the present evaluation it was concluded that although one type of wheelchair was preferable amongst the four examined, it still needed several modifications.     

Directional instability of rear caster wheelchairs

Although less common than conventional front caster wheelchairs, rear caster wheelchairs are still in use for several reasons. Many people find manual rear caster wheelchairs easier to maneuver indoors at slow speeds. This is especially true when the user attempts to maneuver the wheelchair very close to an object, such as a table. Electric wheelchairs often have rear casters to accommodate for front wheel drive. If the larger drive wheels are located at the front of the wheelchair, obstacles such as a curb can be negotiated much more easily. However, a major disadvantage of rear caster wheelchairs is that they are generally known to be directionally unstable, especially at high forward speeds. This paper presents the results of a study to determine specific measures that can be employed to improve the stability of this type of wheelchair. The instability of rear caster wheelchairs is due primarily to road forces that act on the tires when the wheelchair is displaced from its line of motion by a bump or other irregularity in the road surface. The paper discusses the experimental investigation of these road forces as well as a dynamic model used to study the instability problem. The results of a computer simulation program used to perform a parametric study of different design variables are discussed. Center of gravity position, caster trail distance, and caster pin friction are found to have a dominant influence on rear caster wheelchair directional control. Several simple but significant design recommendations are presented.     

An independent shopping experience for wheelchair users through augmented reality and RFID

People with physical and mobility impairments continue to struggle to attain independence in the performance of routine activities and tasks. For example, browsing in a store and interacting with products located beyond an arm’s length may be impossible without the enabling intervention of a human assistant. This research article describes a study undertaken to design, develop, and evaluate potential interaction methods for motor-impaired individuals, specifically those who use wheelchairs. Our study includes a user-centered approach, and a categorization of wheelchair users based upon the severity of their disability and their individual needs. We designed and developed access solutions that utilize radio frequency identification (RFID), augmented reality (AR), and touchscreen technologies in order to help people who use wheelchairs to carry out certain tasks autonomously. In this way, they have been empowered to go shopping independently, free from reliance upon the assistance of others. A total of 18 wheelchair users participated in the completed study.     

Technological and physiological characteristics of a newly developed hand-lever drive system for wheelchairs

It may be concluded that, by use of the newly developed Swing-Turn-gear system, mobility of the disabled person using wheelchairs outdoors can be improved. The qualities of the drive gear in push and pull action, the free wheel, the full selection of frequency, and the range of moving the hand levers represent important progress in wheelchair engineering research. The handrim drive is an alternative, especially for indoor use. But, for the first time, an indoor wheelchair can be offered as a combination vehicle for both indoor and outdoor use. The acceptance of the new wheelchair integrated Swing-Turn-gear is much better than the conspicuous hand-lever drive in standard outdoor wheelchairs. At present, the German wheelchair manufacturer, MEYRA Vlotho, is preparing the new hand-lever drive system for production. Initially, the drive system will be adapted to a standard indoor wheelchair made by this company. Development of a lever drive system is also in progress in the United States, which employs force transmission characteristics in one direction.     

The manual wheelchair wheelie: A review of our current understanding of an important motor skill

Purpose.?To review the current understanding of the manual wheelchair wheelie.

Method.?Review of the literature.

Results.?A rear wheelchair wheelie occurs when the front wheels, ordinarily in contact with the support surface, are intentionally caused, by means of a transient or sustainable rear pitch, to lift from the surface while the rear wheels remain on the surface. Pitch control (partial or full) is the foundation of many wheelchair skills (e.g., negotiating thresholds, potholes, curbs, steep inclines and gravel). Yet, most wheelchair users never learn to perform this valuable skill. Wheelie capability is affected by the characteristics of the clinician, the wheelchair user, the wheelchair and the environment. Although our understanding of wheelie biomechanics and training methods is evolving, much remains to be learned. Three recent wheelchair developments have wheelie-related implications: a new type of rear anti-tip device (Arc-RAD) that permits wheelie-like function, pushrim-activated power-assisted wheelchairs (PAPAWs) that make wheelie-dependent skills more dangerous and difficult, and a powered wheelchair that has robotic wheelie capabilities (the IBOT).

Conclusions.?Improvements in our understanding of the nature of wheelies, formalization of training protocols and innovations in wheelchair design hold promise for improved activities and participation by wheelchair users.     

A drive system to add standing mobility to a manual standing wheelchair

Current manual standing wheelchairs are not mobile in the standing position. The addition of standing mobility may lead to improved health and function for the user and may increase utilization of standing wheelchairs. In this project, a chain drive system was fitted to a manual standing wheelchair, adding mobility in the standing position. The hand rims are accessible from both seated and standing positions. The prototype uses 16-inch drive wheels in front with casters in the rear. Additional anterior casters are elevated when seated for navigating obstacles and then descend when standing to create a six-wheeled base with extended anterior support. Stability testing shows the center of pressure remains within the base of support when leaning to the sides or front in both seated and standing positions. Four veterans with spinal cord injury provided feedback on the design and reported that mobility during standing was very important or extremely important to them. The veterans liked the perceived stability and mobility of the prototype and provided feedback for future refinements. For example, reducing the overall width (width from hand rim to hand rim) and weight could make this system more functional for users.     

Wheelchair caster shimmy and turning resistance

The equations for wheelchair caster wheel shimmy are presented along with experimental data. The report includes the theory and performance of single wheel casters for a variety of tires, and a new design for wheelchair casters using a grooved dual-tread tire or co-rotating caster wheels. The dual-tread tire was found to significantly inhibit caster shimmy. The turning resistance due to a grooved caster wheel tire with a 1/2-inch groove was found to be 10 percent greater than for an ungrooved caster wheel tire. The analysis includes the methodology and the results of experiments developed to measure the sliding friction turning moment of the wheelchair caster wheel. A number of commercial wheelchair caster wheels were tested and the results for shimmy are presented.     

A sports wheelchair for low-income countries

PURPOSE: Appropriate wheelchairs for basic mobility needs are still not commonly available in low-income countries, although several organizations are working toward this goal. After basic mobility is secured it is important to provide more diverse assistive technology to allow people with disabilities to more completely participate in society and live healthy lives. Our goal was to design an affordable sports wheelchair that would allow individuals in low-income countries to participate in basketball. METHODS: Design requirements established for the sports wheelchair included: removable anti-tippers, adjustable tension backrest, 24' wheels, adjustable seat dump, variable camber, 4' casters, fore-aft axle position, removable bumpers, height adjustable footrest, four wheels, single anti-tipper (pivot), cost less than $125 without wheels, 16' seat width and backrest height, and nylon upholstery. The wheelchair was designed using 3D modeling, standard materials, and standard tools. DISCUSSION: An affordable wheelchair, versatile enough to be used for a variety of sports and even everyday use, was designed and prototyped successfully. Documentation for the design including step-by-step directions, engineering drawings, and photographs are available at the Human Engineering Research Laboratories website (http://www.herlpitt.org/intw.htm). Future work on the prototype should include design refinement including adaptations for other sports, and standards testing.     

A sports wheelchair for low-income countries

Purpose. Appropriate wheelchairs for basic mobility needs are still not commonly available in low-income countries, although several organizations are working toward this goal. After basic mobility is secured it is important to provide more diverse assistive technology to allow people with disabilities to more completely participate in society and live healthy lives. Our goal was to design an affordable sports wheelchair that would allow individuals in low-income countries to participate in basketball.

Methods. Design requirements established for the sports wheelchair included: removable anti-tippers, adjustable tension backrest, 24″ wheels, adjustable seat dump, variable camber, 4″ casters, fore-aft axle position, removable bumpers, height adjustable footrest, four wheels, single anti-tipper (pivot), cost less than $125 without wheels, 16″ seat width and backrest height, and nylon upholstery. The wheelchair was designed using 3D modeling, standard materials, and standard tools.

Discussion. An affordable wheelchair, versatile enough to be used for a variety of sports and even everyday use, was designed and prototyped successfully. Documentation for the design including step-by-step directions, engineering drawings, and photographs are available at the Human Engineering Research Laboratories website (http://www.herlpitt.org/intw.htm). Future work on the prototype should include design refinement including adaptations for other sports, and standards testing.     

A longitudinal study assessing the maintenance condition of cadres of four types of wheelchairs provided in low-resource areas

Wheelchair breakdowns increase the risk of injury and limit the mobility of wheelchair users. In the endeavour to meet the enormous global need for wheelchairs, manufacturers of wheelchairs for low-resource settings face a cost–benefit tension between affordability and durability. Field studies are needed to provide feedback on durability. Four manufacturers provided cadres of wheelchairs to the organization providing rehabilitation to students at a boarding school for children with disabilities in a low-resource area. The Wheelchair Components Questionnaire for Condition was used to evaluate wheelchair maintenance condition at several time intervals after fitting. Because the maintenance regime was not identical for the four wheelchair types, wheelchair types were not compared. Analysis of variance indicated differences in condition across time and between wheelchair components. Tukey’s simultaneous comparison of means indicated that across the entire group, brakes, seats, casters and foot rests received lower ratings than frame. Preliminary data after each iteration of this study were provided to manufactures and resulted in responsive design changes.

• Implications for Rehabilitation

• Longitudinal studies with the Wheelchair Components Questionnaire for Condition (WCQc) have enabled manufacturers to make responsive design improvements. Additional studies could be done with other wheelchair types to result in responsive positive design changes for those wheelchairs as well.

• The WCQc can be used in studies on wheelchair condition even when records of repair history are not reliably available, a situation which is not uncommon in low-resource areas.

• Data sets collected at an individual clinic uses the WCQc could focus attention on wheelchair components needing regular repair. With that data in mind, the maintenance regime could be modified to respond and in so doing improve wheelchair condition and reduce loss of mobility or risk of injury.

• Organizations involved in funding wheelchairs for a particular location could use data from longitudinal studies done with the WCQc at that location to inform purchasing decisions.

     

Wheelchair use by veterans newly prescribed a manual wheelchair

OBJECTIVE: To describe the characteristics of the wheelchairs, the users, and their wheelchair use among persons newly prescribed a manual wheelchair. DESIGN: Cohort study. SETTING: Veterans Affairs teaching hospital. PARTICIPANTS: Ninety-nine consecutive, cognitively intact veterans prescribed a manual wheelchair. INTERVENTIONS: Not applicable. MAIN OUTCOME MEASURES: Self-reported difficulty transferring into and propelling the wheelchair; and bathroom mobility method. RESULTS: Study patients had a mean age of 66 and a mean of 10 comorbid medical conditions. Parkinsonism, osteoporosis, joint replacement, and amputation were uncommon (<30% of patients), but had a high impact on need for a wheelchair (when present were reported by >50% of patients as causing need for a wheelchair). Falls and arthritis were common (>50% of patients) and highly impacted need for a wheelchair. At 1 month, over 30% of patients had wheelchairs that did not meet common criteria for wheelchair fit; 36% and 61%, respectively, reported difficulty transferring and propelling the wheelchair. The wheelchairs were used for bathroom mobility by 38% of the patients. CONCLUSIONS: The typical manual wheelchair recipient in this study sample was old with multiple medical problems. Despite provision of manual wheelchairs by trained professionals and availability of diverse wheelchair types, new wheelchair users commonly reported difficulty using the wheelchair.     

Usability testing of multimodal feedback interface and simulated collision-avoidance power wheelchair for long-term-care home residents with cognitive impairments

Many older adults in long-term-care homes have complex physical and cognitive impairments and have difficulty propelling manual wheelchairs. Power wheelchair use is restricted owing to safety concerns. Power wheelchairs with collision-avoidance features are being developed to enable safe and independent mobility; however, a paucity of information exists on interface features to help users navigate away from obstacles. We developed a system combining an interface with auditory, visual, and haptic feedback and a simulated collision-avoidance power wheelchair. This device allowed the investigator to stop movement of the power wheelchair when users approached obstacles and to deliver feedback to help them navigate. Five long-term-care home residents with mild or moderate cognitive impairments evaluated device usability, which included effectiveness, efficiency, and user satisfaction. Each resident used the device for six 1 h sessions. Observations, feedback interviews, and outcome questionnaires were completed during and after the sessions. We found the device effective in enabling residents to achieve basic driving tasks and self-identified indoor mobility goals. Furthermore, residents perceived workload to be low and were satisfied with the device. Residents also felt that the feedback was useful to help them navigate away from obstacles.     

Issues in maintenance and repairs of wheelchairs: A pilot study

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.     

Evaluation of selected ultralight manual wheelchairs using ANSI/RESNA standards

OBJECTIVES: To provide data for clinicians and wheelchair users to compare the durability, strength, stability, and cost effectiveness of four different ultralight wheelchair models, and to compare the results of this study with those published for lightweight wheelchairs. DESIGN: Standards testing and cost-effectiveness analysis of four wheelchair models from different manufacturers (12 wheelchairs total). RESULTS: There were significant differences (p< or =.05) in the fatigue life and value (equivalent cycles per dollar) among the ultralight wheelchairs tested. There was also a significant difference (p< or =.05) in rearward stability tilt angle for the least and most stable configurations. There were no differences in forward and lateral stability. The ultralight wheelchairs (1,009,108 cycles) had significantly (p< or =.05) higher fatigue lives than previously reported for lightweight wheelchairs (187,370 cycles). The lightweight wheelchairs had a mean value of 210 cycles per dollar compared to 673 cycles per dollar for the ultralight wheelchairs. The difference in value for the lightweight and ultralight wheelchairs was statistically significant (p< or =.05). CONCLUSION: There were differences in the fatigue life and value among the four models of ultralight manual wheelchairs tested. This indicates that ultralight manual wheelchairs are not all of equal quality. The fatigue life and value of the ultralight manual wheelchairs were significantly higher than those previously reported for lightweight manual wheelchairs. This indicates that ultralight wheelchairs may be of higher quality than lightweight manual wheelchairs. Clinicians and consumers should seriously consider selecting an ultralight manual wheelchair to meet their wheelchair mobility needs.