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Rory A Cooper

Publications and source records attributed to Rory A Cooper.

At least 19 recordsLinked to original sources
PubMed2005

Fatigue testing of selected suspension manual wheelchairs using ANSI/RESNA standards.

OBJECTIVES: To evaluate the durability and value of 3 common suspension manual wheelchairs and to compare the results with those of previously tested lightweight and ultra-lightweight folding-frame wheelchairs. DESIGN: Standardized fatigue testing and cost analysis of 3 suspension manual wheelchairs from 3 different manufacturers. SETTING: A rehabilitation engineering center. SPECIMENS: Nine suspension manual wheelchairs. INTERVENTIONS: Wheelchairs were fitted with a standardized wheelchair test dummy and tested on a series of fatigue tests, consistent with those developed by the International Organization for Standardization. Main outcome measures Fatigue life (measured as the number of equivalent cycles completed) and value (equivalent cycles divided by cost) were compared among all wheelchairs. RESULTS: Analysis of variance revealed significant differences (P< or =.05) in the number of equivalent cycles among the suspension wheelchairs tested. When compared with previously tested ultra-lightweight and lightweight wheelchairs, the suspension wheelchairs failed to show significant improvements; however, significant improvements were found between individual suspension and lightweight wheelchairs. CONCLUSIONS: We found little evidence to suggest that suspension manual wheelchairs provide advantages in terms of durability or value over standard lightweight and ultra-lightweight folding-frame wheelchairs.

Equipment Design↗
PubMed2004

Evaluation of selected electric-powered wheelchairs using the ANSI/RESNA standards.

OBJECTIVES: To compare the performance characteristics of different electric-powered wheelchairs (EPWs) and to evaluate the effectiveness of the American National Standards Institute/Rehabilitation Engineering and Assistive Technology Society of North America (ANSI/RESNA) wheelchair standards. DESIGN: Five types of EPWs were selected. Three wheelchairs of each type were tested according to the ANSI/RESNA wheelchair standards. SETTING: Rehabilitation engineering center. SPECIMENS: Fifteen wheelchairs. INTERVENTIONS: Not applicable. MAIN OUTCOME MEASURES: Static tipping angle; dynamic tipping score; braking distance; energy consumption; static, impact, and fatigue strength; and climatic conditioning. RESULTS: There were significant differences (P<.05) among the 5 types of EPWs for static stability when facing both uphill and downhill in the most-stable and least-stable configurations. There were significant differences (P<.05) among the EPWs on most of the dynamic stability tests. There were also significant differences (P<.05) among EPWs for all the effectiveness of brakes conditions, as well as between 2 wheelchairs for the energy consumption testing. There were several failures among the wheelchairs during the static, impact, and fatigue strength testing and during the climatic testing. CONCLUSIONS: The results show that EPWs can vary greatly with respect to static and dynamic stability, braking distance, range, strength testing, and climatic conditioning. All these factors have a substantial effect on safety and performance.

Equipment Design↗
PubMed2004

Manual wheelchair pushrim dynamics in people with multiple sclerosis.

OBJECTIVES: To define differences in pushrim dynamics during manual wheelchair propulsion by users with multiple sclerosis (MS) relative to 2 control groups of subjects with spinal cord injury (SCI) and no disability (ND) and to investigate changes in propulsion biomechanics at different speeds and with fatigue. DESIGN: Case-control. SETTING: Biomechanics laboratory. PARTICIPANTS: A convenience sample of 42 people, 8 women and 6 men per group. INTERVENTIONS: Not applicable. MAIN OUTCOME MEASURES: The propulsion pattern, mean maximum speed, percentage of time in push and recovery phases, push angle, push frequency, mean maximum resultant pushrim force, mean work and push cycle, and hand-to-pushrim coupling and decoupling effects. RESULTS: The MS groups tended to use an arcing propulsion pattern more than did the control groups (Pmax=.003). The MS group pushed at a lower mean maximum velocity (v) when allowed to choose the speed of propulsion (v(MS),.67+/-.20m/s; v(SCI), 1.10+/-0.23m/s; P=.001), when asked to push at 1m/s (v(MS),.91+/-.26m/s; v(SCI), 1.12+/-0.11m/s; v(ND), 1.05+/-0.13m/s; P=.010), and were unable to maintain a self-selected speed during a 5-minute trial (Deltav(MS),.15+/-.02m/s; Deltav(ND),.03+/-.06m/s; P<.001). The MS group spent a higher proportion of time in the push phase of propulsion (Pmax=.001). In general, the MS group had smaller push angles, but push frequencies similar to the controls. Statistically adjusted MS group pushrim forces and work per push measures varied depending on context, but in all trials the MS group displayed a braking effect when grasping and releasing the pushrim. The MS group had declines in most measures when pushing at a self-selected speed for 5 minutes. In all trials, the MS group was more likely to display asymmetry between right and left sides in biomechanic parameters. CONCLUSIONS: Manual wheelchair users with MS have difficulty grasping and releasing the pushrim and maintaining speed during a fatigue trial. This likely leads to a slow self-selected speed of propulsion that may not be functional. Clinicians should remember these results when prescribing manual wheelchairs for people with MS.

Acceleration↗
PubMed2004

Durability, value, and reliability of selected electric powered wheelchairs.

OBJECTIVE: To compare the durability, value, and reliability of selected electric powered wheelchairs (EPWs), purchased in 1998. DESIGN: Engineering standards tests of quality and performance. SETTING: A rehabilitation engineering center. SPECIMENS: Fifteen EPWs: 3 each of the Jazzy, Quickie, Lancer, Arrow, and Chairman models. INTERVENTIONS: Not applicable. MAIN OUTCOME MEASURES: Wheelchairs were evaluated for durability (lifespan), value (durability, cost), and reliability (rate of repairs) using 2-drum and curb-drop machines in accordance with the standards of the American National Standards Institute and Rehabilitation Engineering and Assistive Technology Society of North America. RESULTS: The 5 brands differed significantly (P<or=.05) in durability, value, and reliability, except in terms of reliability of supplier repairs. The Arrow had the highest durability, value, and reliability in terms of the number of consumer failures, supplier failures, repairs, failures, consumer repairs and failures, and supplier repairs and failures. The Lancer had the poorest durability and reliability, and the Chairman had the lowest value. K0014 wheelchairs (Arrow, Permobil) were significantly more durable than K0011 wheelchairs (Jazzy, Quickie, Lancer). No significant differences in durability with respect to rear-wheel-drive (Arrow, Lancer, Quickie), mid-wheel-drive (Jazzy), or front-wheel-drive (Chairman) wheelchairs were found. CONCLUSIONS: The Arrow consistently outperformed the other wheelchairs in nearly every area studied, and K0014 wheelchairs were more durable than K0011 wheelchairs. These results can be used as an objective comparison guide for clinicians and consumers, as long as they are used in conjunction with other important selection criteria. Manufacturers can use these results as a guide for continued efforts to produce higher quality wheelchairs. Care should be taken when making comparisons, however, because the 5 brands had different features. Purchased in 1998, these models may be used for several more years. In addition, problem areas in these models may still be present in newer models.

Electricity↗
PubMed2004

Relation between median and ulnar nerve function and wrist kinematics during wheelchair propulsion.

OBJECTIVE: To investigate the relation between median and ulnar nerve health and wrist kinematics in wheelchair users. DESIGN: Case series. SETTING: Biomechanics laboratory and electrodiagnostic laboratory at a Veterans Health Administration medical center and a university hospital, respectively. PARTICIPANTS: Thirty-five people with spinal cord injury who use manual wheelchairs. INTERVENTION: Subjects propelled their own wheelchair on a dynamometer at 0.9 and 1.8m/s. Bilateral biomechanic data were obtained by using force and moment sensing pushrims and a kinematic system. Bilateral median and ulnar nerve conduction studies were also completed. MAIN OUTCOME MEASURES: Wrist flexion, extension, radial and ulnar deviation peaks, and ranges of motion (ROMs) as related to median and ulnar motor and sensory amplitudes. A secondary analysis included peak pushrim forces and moments and stroke frequency. RESULTS: There was a significant, positive correlation between flexion and extension ROM and both ulnar motor amplitude (r=.383, P<.05) and median motor amplitude (r=.361, P<.05). CONCLUSIONS: Contrary to our hypothesis, subjects using a greater ROM showed better nerve function than subjects propelling with a smaller ROM. Subjects using a larger ROM used less force and fewer strokes to propel their wheelchairs at a given speed. It is possible that long, smooth strokes may benefit nerve health in manual wheelchair users.

Adolescent↗
PubMed2004

Assessing the influence of wheelchair technology on perception of participation in spinal cord injury.

OBJECTIVE: To investigate factors related to the wheelchair, impairment, and environment that affect perception of participation of persons with spinal cord injury (SCI) in activities performed in 3 settings: in the home, in the community, and during transportation. DESIGN: Cross-sectional study. SETTING: Research centers and a specialized assistive technology (AT) clinic in Pittsburgh (Pitt). Research centers and community-based rehabilitation technology suppliers in Saint Louis (SL). PARTICIPANTS: Seventy wheelchair users with SCI. INTERVENTIONS: Subjects from Pitt and SL completed a written survey of AT usage in daily activities. MAIN OUTCOME MEASURES: Subjects were asked 5 questions within each setting (home, community, transportation) related to their perceived reason for functional limitations. RESULTS: The wheelchair was the most commonly cited factor limiting participation, followed by physical impairment and physical environment. Twenty-one percent of subjects with paraplegia reported pain as a limiting factor for their transportation use, significantly more (P=.047) than subjects with tetraplegia (3%). A trend (P=.099) was seen toward a higher percentage of subjects with tetraplegia (tetraplegia, 7%; paraplegia, 3%) reporting lack of equipment as a limiting factor for use of transportation. Differences were also seen across sites. CONCLUSIONS: The wheelchair was the most commonly cited limiting factor, followed by physical impairment and physical environment. The wheelchair is the most important mobility device used by persons with SCI and the one that users most associate with barriers.

Activities of Daily Living↗
PubMed2004

Impact of a pushrim-activated power-assisted wheelchair on the metabolic demands, stroke frequency, and range of motion among subjects with tetraplegia.

OBJECTIVES: To determine differences in metabolic demands, stroke frequency, and upper-extremity joint range of motion (ROM) during pushrim-activated power-assisted wheelchair (PAPAW) propulsion and traditional manual wheelchair propulsion among subjects with tetraplegia. DESIGN: Repeated measures. SETTING: A biomechanics laboratory within a Veterans Affairs medical center. PARTICIPANTS: Fifteen full-time manual wheelchair users who had sustained cervical-level spinal cord injuries. INTERVENTIONS: Participants propelled both their own manual wheelchairs and a PAPAW through 3 different resistances (slight, 10W; moderate, 12W; high, 14W) on a wheelchair dynamometer. Each propulsion trial was 3 minutes long. MAIN OUTCOME MEASURES: Primary variables that were compared between the 2 wheelchairs were participants mean steady-state oxygen consumption, ventilation, heart rate, mean stroke frequency, and maximum upper-extremity joint ROM. RESULTS: When using the PAPAW, participants showed a significant ( P <.05) decrease in mean oxygen consumption and ventilation throughout all trials. Mean heart rate was significantly lower when using the PAPAW for the high resistance trial. Stroke frequency was significantly lower when using the PAPAW for the slight and moderate resistances. Overall joint ROM was significantly lower when using the PAPAW. CONCLUSIONS: For subjects with tetraplegia, PAPAWs reduce the energy demands, stroke frequency, and overall joint ROM when compared with traditional manual wheelchair propulsion.

Adult↗
PubMed2004

Demographic and socioeconomic factors associated with disparity in wheelchair customizability among people with traumatic spinal cord injury.

OBJECTIVES: To determine if a standard of care for wheelchair provision exists within the participating centers and if there is disparity in wheelchair customizability among the study sample. DESIGN: Convenience sample survey. SETTING: Thirteen Model Spinal Cord Injury Systems that provide comprehensive rehabilitation for people with traumatic spinal cord injury (SCI) and that are part of the national database funded through the US Department of Education. PARTICIPANTS: A total of 412 people with SCI who use wheelchairs over 40 hours a week. INTERVENTION: Survey information was obtained from subjects via telephone and in-person interviews and from the national database. Collected information included age, race, education, level of injury, and wheelchair funding source. MAIN OUTCOME MEASURES: Number and type (manual or power) of wheelchairs. Wheelchair customizability as defined by design features (eg, adjustable axle position, programmable controls). RESULTS: Ninety-seven percent of manual wheelchair users and 54% of power wheelchair users had customizable wheelchairs. No power wheelchair user received a wheelchair without programmable controls. Minorities with low socioeconomic backgrounds (low income, Medicaid/Medicare recipients, less educated) were more likely to have standard manual and standard programmable power wheelchairs. Older subjects were also more likely to have standard programmable power wheelchairs. CONCLUSIONS: The standard of care for manual wheelchair users with SCI is a lightweight and customizable wheelchair. The standard of care for power wheelchairs users has programmable controls. Unfortunately, socioeconomically disadvantaged people were less likely to receive customizable wheelchairs.

Activities of Daily Living↗
PubMed2004

The GAME(Cycle) exercise system: comparison with standard ergometry.

BACKGROUND: It is well established that physical activity is beneficial to health. For the individual in a wheelchair, a regular exercise program might not be available or may be too difficult to participate in physically and/or psychologically. Many exercise devices and regimes are boring. The goal, therefore, is to develop a device that makes exercise more exciting and, thus, motivates a person to exercise more or for a longer period of time, yielding increased energy expenditure. Our laboratory developed an interface between an arm ergometer and a computer game that allows the user to control game play on the screen as if using a joystick. The purpose of this study was to determine (a) whether the GAME(Cycle) system would elicit an exercise effect similar to arm ergometry, (b) whether perceived exertion would be different between the 2 devices, and (c) individuals' impressions regarding the GAME(Cycle) system. METHODS: Thirteen individuals who used wheelchairs participated in the study. Participants were asked to exercise for 2 separate, 19-minute sessions. For 1 session, a GAME(Cycle) system was used and for the other session, the same arm ergometer was used, but without the computer game being played. Physiologic data and perceived exertion were collected for each session. RESULTS: There were significant differences between playing the game and not playing the game for VO2 (P = 0.03) and VCO2 (P = 0.02), with higher values being found when the game was played. Perceived exertion was not significantly different between the 2 trials. CONCLUSION: GAME(Cycle) appears to be similar in nature with respect to energy expenditure to arm ergometry. Because this study was conducted on athletes, further research is needed with sedentary individuals to determine exercise effects and perceived exertion.

Adult↗
PubMed2004

Evaluation of selected sidewalk pavement surfaces for vibration experienced by users of manual and powered wheelchairs.

BACKGROUND: Obstacles such as bumps, curb descents, and uneven driving surfaces cause vibrations that affect the wheelchair, and in turn, the wheelchair user. Chronic exposure can cause low-back pain, disk degeneration, and other harmful effects. Little research has been conducted to assess the vibrations experienced by wheelchair users. OBJECTIVE: The purpose of this study was to conduct an evaluation of the vibration exposure during electric-powered wheelchair driving and mechanical energy requirements for manual wheelchair propulsion over selected sidewalk surfaces. The goal was to determine the criteria for a wheelchair-pedestrian access route that does not require excessive propulsive work or expose wheelchair users to potentially harmful vibrations. METHODS: Ten unimpaired individuals participated in this study. Six sidewalk surfaces were tested. Measured variables included power of the acceleration per octave, mechanical work to propel over surfaces, peak acceleration, and frequency at which peak acceleration occurs. RESULTS: For both the manual and electric-powered wheelchair, at 1 m/s, significant differences were found in peak accelerations between the seat and footrest (P < 0.0001) and between the sidewalk surfaces (P = 0.004). The greatest risk for injury caused by shock and vibration exposure occurs at frequencies near the natural frequency of seated humans (4-15 Hz). The values for work required to propel over the surfaces tested were not statistically significantly different. Besides appearance and construction, the only distinguishing characteristic was surface roughness caused by the joints. CONCLUSION: When treating the poured concrete sidewalk as the standard, surfaces 2, 3, 5, and 6 compared most favorably in terms of vibration exposure, whereas surface 4 produced mixed results. Surfaces 2, 3, 5, and 6 yielded results that were similar to the poured concrete sidewalk and could be considered acceptable for wheelchair users. In conclusion, surfaces other than the traditional poured concrete can be used for pedestrian access routes without adding vibration exposure or reducing propulsion efficiency.

Adult↗
PubMed2004

Bioengineering and spinal cord injury: a perspective on the state of the science.

There is little doubt that as technologic advances become available, people with spinal cord injuries (SCIs) are living healthier, more productive, and longer lives. Federally and privately funded research, foreign competition, and globalization appear to be factors that will drive bioengineering advances within the assistive technology (AT) industry. The seeds of bioengineering research are likely to contribute to improvements in universal design and the mainstreaming of products. The aims of AT have changed tremendously in the past 50 years. Most of the federal agencies supporting assistive and rehabilitative technology research and development did not exist 50 years ago. Indeed, the leading AT companies all were established within the past 50 years. Bioengineering has the potential to be to the 21 st century what electronic engineering was to the 20th century. Advances in power electronics, telecommunications, controls, sensors, and instrumentation have really only just begun to be applied for devices to assist people with SCI. Advancing technology for people with SCI represents a significant career and business opportunity for engineers who want to serve the public good in a meaningful and tangible way.

Biomedical Engineering↗
PubMed2004

Development of a consumer-driven Wheelchair Seating Discomfort Assessment Tool (WcS-DAT).

This study examined the concept of seating discomfort in a population of full-time wheelchair users with intact sensation. The goal was to construct a tool that would quantify seating discomfort experienced by wheelchair users. Ten participants were interviewed using ethnographic interview techniques. Data were analyzed using a cross-classifying matrix to examine commonalities among the 10 participants' responses. There were 16 discomfort and 13 comfort descriptors used by the participants. Of these, eight discomfort and five comfort descriptors were selected to include in the Wheelchair Seating Discomfort Assessment Tool (WcS-DAT). The discomfort descriptors selected were: aches and pains, need to move, pressure points, feeling poorly positioned, unable to concentrate, instability, not comfortable, and feeling too hot, cold or damp. The comfort descriptors selected were: absence of discomfort, feeling good, having no pain, able to concentrate, and feeling stable. The WcS-DAT also includes general information, such as the amount of time spent sitting and whether the individual was transferred into the chair properly--factors thought to affect discomfort--and ratings of discomfort intensity--in general and differentiated by body area. The WcS-DAT is a comprehensive tool for quantification of wheelchair seat discomfort for this population.

Adult↗
PubMed2004

Push for power.

Explore the source record for details and available documents.

Electric Power Supplies↗
PubMed2004

Preliminary assessment of a prototype advanced mobility device in the work environment of veterans with spinal cord injury.

The INDEPENDENCE 3000 IBOT Transporter (IBOT) is an electronically stabilizing device for people with disabilities. The purpose of this study was to collect qualitative data on the potential for the IBOT to improve employment satisfaction of veterans who use wheelchairs to work. This study was based upon observations by trained clinicians, and responses to a survey completed by four men with traumatic spinal cord injury, who worked in an office environment. The mean age of the subjects was 52 +/- 8.8 years. The subjects used the devices to hold eye-level discussions with colleagues, climb stairs, ascend steep ramps, and negotiate curbs. When subjects were asked to rate the ease of getting around in the IBOT compared to their personal wheelchairs, they responded with a mean of 6.7 +/- 1.8 on a 10-point visual analog scale. The response to rating the overall function of the IBOT within their working environment yielded a rating of 6.0 +/- 2.8. Half of the users felt that the IBOT would help them at work and all thought it should be made available to veterans who use wheelchairs. A larger study should be conducted to determine if the IBOT affects work performance and the ability to return to work.

Employment↗
PubMed2003

Tips and falls during electric-powered wheelchair driving: effects of seatbelt use, legrests, and driving speed.

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

Acceleration↗
PubMed2003

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

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.

Acceleration↗
PubMed2003

Shoulder magnetic resonance imaging abnormalities, wheelchair propulsion, and gender.

OBJECTIVE: To investigate the relationship between pushrim forces and the progression of shoulder injuries in manual wheelchair users. DESIGN: Longitudinal case series. SETTING: Biomechanics laboratory and magnetic resonance imaging (MRI) facility at a Veterans Health Administration medical center and university hospital, respectively. PARTICIPANTS: Fourteen individuals with spinal cord injury (8 men, 6 women) who used manual wheelchairs. INTERVENTION: Subjects propelled their own wheelchairs on a dynamometer at 0.9 and 1.8m/s. Bilateral biomechanical data were obtained by using force and moment sensing pushrims at time 1. Bilateral shoulder MR images were also completed on 2 occasions, at time 1 and, approximately 2 years later, at time 2. MAIN OUTCOME MEASURES: The peak pushrim forces in a pushrim coordinate system were calculated, weight normalized and averaged over 5 strokes (presented as % body weight). MRI abnormalities were graded by using a summated scale. Differences between scores between times 1 and 2 were calculated. RESULTS: Subjects were divided into 2 groups based on change in MRI score. Seven subjects were in the group with worsening scores (MRI+; mean, 8.14 points; range, 5-16), and 7 were in the group with improving or unchanging scores (MRI-; mean, -1.00 point; range, -5 to 1). There was no significant difference between groups with respect to age, body mass index, or years from injury. There were significantly more women in the MRI+ group (6 women, 1 man) than in the MRI- group (7 men) (P=.001). The MRI+ group used significantly greater weight-normalized radial force, or force directed toward the axle at time 1, to propel their wheelchairs at each speed (P<.01): MRI+ at 0.9m/s (mean radial force +/- standard deviation, 5.2%+/-1.0%) and MRI- at 0.9m/s (mean radial force, 3.2%+/-1.7%) (P=.028); and MRI+ at 1.8m/s (mean radial force, 6.6%+/-1.2%) (P=.023) and MRI- at 1.8m/s (mean radial force, 4.1%+/-2.2%). In a separate analysis, women were found to propel with a significantly higher radial force. A logistic regression found a significant relationship between radial force at time 1 and increased risk of progression of MRI findings over time. CONCLUSION: Individuals who propel with a greater percentage of force directed toward the axle were at increased risk of progression of MRI findings over time. Most people in this group were women. Clinicians should instruct wheelchair users in effective propulsion techniques and should pay particular attention to women who use wheelchairs. Reducing forces during wheelchair propulsion may minimize the likelihood of developing shoulder injuries.

Adult↗