Impact and Usage of Pushrim Activated Power Assist Wheelchair among Individuals with Tetraplegia

Ana Souza, MS; Dan Ding, PhD; Rosemarie Cooper, MPT, ATP; Rory Cooper, PhD; Annmarie Kelleher, OTR/L, ATP; Michael Boninger, MD

Department of Rehabilitation Science and Technology, University of Pittsburgh, and Human Engineering Research Laboratories, VA Pittsburgh Healthcare System
Pittsburgh, PA 15206


The purpose of this study was to evaluate the impact and usage of Pushrim Activated Power Assist Wheelchairs (PAPAWs) on mobility and psychosocial impact among individuals with tetraplegia. Fifteen manual wheelchair users (MWU) with tetraplegia completed a four-week protocol including a two-week trial where they used their personal wheelchairs for mobility and a two-week trial where they were provided with a PAPAW and could choose either wheelchair for mobility. The mobility levels with both wheelchairs were recorded by a MWU datalogger. The Psychosocial Impact of Assistive Devices Survey (PIADS) was conducted to compare the psychosocial impact of PAPAWs with their personal wheelchairs. Participants chose to use PAPAWs and their personal wheelchairs at a similar frequency in the PAPAW trial, but tended to travel further and spent more time with PAPAWs. They also traveled significantly faster with PAPAWs (p = 0.03). PAPAWs also resulted in greater psychosocial impacts than the personal wheelchairs.


power-assisted wheelchairs, usage, mobility, tetraplegia


Many individuals with Spinal Cord Injury (SCI) rely on wheelchairs as their primary means of mobility. Individuals with paraplegia are usually capable of propelling manual wheelchairs, while those with cervical-level injuries (tetraplegia) often find manual wheelchair propulsion more difficult due to decreased physical capacity and reduced upper extremity strength (1). Wheelchair propulsion over time also increases injuries and pain in upper extremity especially in individuals with tetraplegia (2-4). Although power wheelchairs can provide an effective means of mobility for those who are less efficient in propelling a manual wheelchair, they are typically larger, heavier, and create accessibility issues within the home environment and transportation. The Pushrim Activated Power Assist Wheelchair (PAPAW) (see Figure 1) has been developed in recent years to offer an option between manual and power wheelchairs. PAPAWs have demonstrated feasibility and commercial soundness among the alternative mobility devices. They are typically manual wheelchairs with a motor linked to the pushrim in each rear hub, where the pushrim input is sensed and amplified proportionally by the motor (2).

Photo 1: The PAPAW with a datalogger attached (Click for larger view)

Algood et al. (5,6) conducted a two-phase study where fifteen manual wheelchair users with tetraplegia were recruited to test the PAPAW in a laboratory setting. The first phase examined the differences in mean steady-state oxygen consumption, ventilation, heart rate, mean stroke frequency, and maximum upper-extremity joint range of motion during PAPAW propulsion and traditional manual wheelchair propulsion. Results revealed a significant improvement in kinematics, speed, and metabolic variables when participants propelled a PAPAW. The second phase examined the differences between a PAPAW and a traditional manual wheelchair when participants performed common driving activities in a simulated setting. Results showed PAPAWs received higher user ratings than traditional manual wheelchairs for 10 out of 18 obstacles. Additionally, participants were able to complete the course in the same amount of time while maintaining a lower mean heart rate when using a PAPAW. The present study continues with the previous two-phase protocol with the purpose to evaluate the impact and usage of PAPAWs on mobility and psychosocial impact among individuals with tetraplegia. Fitzgerald et al. (2003) conducted the only study that evaluated a PAPAW in real-life environments with seven wheelchair users with paraplegia. The results did not reveal a significant difference between PAPAWs and manual wheelchairs in terms of distance traveled and average speed recorded by a data logging device, however 6 subjects reported that ease of use was what they liked best about a PAPAW (7).


Our study hypotheses were:

  1. Subjects would use PAPAWs more hours of the day, travel more miles, and at a higher speed than their personal wheelchair as measured by a manual wheelchair datalogger;
  2. Subjects’ perception on competence, adaptability and self-esteem would be higher with PAPAWs than their personal wheelchairs as measured by the Psychosocial Impact of Assistive Devices Survey (PIADS).



This study received prior approval by the appropriate human studies institutional review boards. Each participant was provided with information about the safety and intent of the tests, and informed consent was obtained prior to testing. The inclusion criteria were: (1) full-time manual wheelchair users, (2) between 18 and 65 years old, (3) cervical level spinal cord injury, (4) free from pressure sores and shoulder pain prior to the study, and (5) no history of cardiopulmonary disease.


The study used a cross-over design with subjects acting as their own controls. The protocol consisted of a four-week trial including a two-week trial where subjects used their personal wheelchairs for mobility (denoted as own chair trial) and a two-week trial where they were provided with a PAPAW and instructed to use either wheelchair for mobility according to their preference (denoted as PAPAW trial). including: age, gender, weight, injury level, years of wheelchair use, and type/model of their personal wheelchair. The PAPAWs used in this study were equipped with the JWII (Yamaha Motor Corporation), hubs and frames were chosen to match the dimensions and setup of subjects’ personal wheelchairs. Subjects were asked to complete a demographic survey after informed consent, and complete a daily survey questionnaire regarding obstacles preventing travel outside the home, satisfaction and dissatisfaction with the PAPAW, type of wheelchair used, places visited, and methods of passing obstacles. Due to the limited space, the daily survey will not be included in this paper. At the end of each two-week trial, the Psychosocial Impact of Assistive Devices (PIADS) survey was conducted to assess the effects of the PAPAW and the personal wheelchair on the user’s competence, adaptability, and self-esteem.

Data Analysis:

Descriptive statistics including means and standard deviations for continuous data and frequencies for categorical data were calculated for all variables. The mobility variables for the PAPAW and the personal wheelchair during the PAPAW trial, and the personal wheelchair during the own chair trial were first analyzed with repeated measurements to determine if there were any significant changes over time. As no significant differences were found, we concluded that there was no sudden behavior change during the study period and all the variables were averaged over 14 days for comparison. All data were examined for normalcy. Based on the normalcy, either a Wilcoxon Signed Ranks test or a paired t-test was used to compare the PAPAW with the personal wheelchair on mobility and psychosocial impact. Statistical significance was set at 0.05.


Fifteen full-time manual wheelchair users with spinal cord injury level C3-C6 completed the study. There were 12 males and 3 females; they ranged in age from 18 to 59 years old with a mean of 38.3 ± 10.5 years old. Table 1 shows the average daily distance traveled, the actual driving time and average speed during the own chair trial and the PAPAW trial. There was no significant differences for both the distance (p = 0.09) and the accumulated driving time (p = 0.17) during PAPAW trial. The same test used for distance and time also showed there were no significant differences in the total distance and time between the PAPAW trial and the own chair trial (p = 0.16 for distance, p = 0.33 for time). In terms of the speed traveled, a significant difference (p = 0.03) was found between PAPAWs and personal wheelchairs during the PAPAW trial using a paired t-test. Participants traveled at an average speed of 0.74 ± 0.31 m/s with PAPAWs and 0.60 ± 0.23 m/s with their personal wheelchairs during the PAPAW trial. They also traveled significantly faster with PAPAWs during the PAPAW trial than with their personal wheelchairs during the own chair trial (p = 0.04). The ratings of adaptability, competency and self-esteem obtained through the PIADS survey were found to be higher for the PAPAW than their personal wheelchair, although no significances were found (p=0.18, p= 0.07 and p=0.09, respectively) (Table 2).

Table 1: Wheelchair Usage: Average daily distance, driving time and average speed driven during the own chair trial and the PAPAW trial
    Distance (m) Time (min) Average Speed  (m/s) P Value (Distance) P Value (Speed) P Value (Time)
Own Chair Trial Personal Chair
43.7+ 24.4
0.62+ 0.18
PAPAW Trial** Total    
     2230.0 + 2120.9
50.3+ 33.2
Personal Chair
711.7 +967.4
16.6 + 18.6
0.60 + 0.23
1518.3 +1620.0
  * the average speed of a PAPAW in the PAPAW trial
  **Note: During the PAPAW trial, subjects were instructed to feel free to use their own wheelchairs according to their preference.


Table 2: Psychosocial Impact of Assistive Devices (PIADS) Survey Score





Personal Wheelchair

1.1 ± 1.2

1.1 ± 1.3

0.8 ± 1.2


1.8 ± 1.0

1.7 ± 1.2

1.5 ± 1.1

P Value





There was no significant difference found in the daily distance and driving time between subjects’ own chair trial and the PAPAW trial, similar to the findings of Fitzgerald et al. (7). One reason, as pointed out in (7), could be that people have behavioral and social routines that dictate where and when they go to places. However, a significant difference in the distance and driving time were seen between the PAPAW and the personal wheelchair during the PAPAW trial, where participants had the choice to use any chair according to their preference.

In terms of the driving speed, significant differences were found between the two wheelchairs in the PAPAW trial and in separate trials as well. With the power assist function, a PAPAW could allow participants to move faster than a traditional manual wheelchair. Being able to propel faster and more efficiently is very important especially for individuals with tetraplegia since they usually require more physical strain and longer time to perform their ADLs compared to individuals with paraplegia. Overall, participants reported less effort and easier propelling with the PAPAW, allowing them to go out of their homes more often and with less physical strain.

Although no statistical significant differences were found between the two wheelchairs, the PIADS scores were significantly higher in all three categories with the PAPAW. PAPAWs resulted in greater satisfaction and psychosocial impacts than participants’ personal wheelchairs.

One limitation of the study is that the two-week trial may not be sufficient for wheelchair users to adapt to a new wheelchair and change habits, especially when they know that they have to return the PAPAWs after the trial. Future work will include recruiting more subjects, analyzing wheelchair usage excluding non-typical days (e.g. adverse weather, health problem etc), examining daily usage variations, surveying subjects’ satisfaction with their personal wheelchairs, and conducting longer trials.


  1. Beekman CE, Miller-Porter L, Schoneberger W. (1999). Energy cost of propulsion in standard and  ultralight wheelchairs in people with spinal cord injuries. Physical Therapy, 79(2):146-58.
  2. Boninger ML, Cooper RA, Baldwin MA, Shimada SD, Koontz A. (1999). Wheelchair pushrim  kinetics: body weight and median nerve function. Archives of Physical Medicine and Rehabilitation  80(8):910-5.
  3. Dyson-Hudson, T. A., & Kirshblum, S. C. (2004). Shoulder pain in chronic spinal cord injury, Part I:     Epidemiology, etiology, and pathomechanics. Journal of Spinal Cord Medicine, 27(1), 4-17.
  4. Levy, C.E., Chow, J.W. (2004). Pushrim-Activated power-Assist Wheelchairs: Elegance in motion,  Am J Phys Med Rehab, 83(2):166-167.
  5. Algood SD, Cooper RA, Fitzgerald SG, Cooper R, Boninger ML. (2004). Impact of pushrim-activated power-assist wheelchair on the metabolic demands, stroke frequency, and range of motion among subjects with tetraplegia. Archives of Physical Medicine & Rehabilitation 85(11):1865-71.
  6. Algood SD, Cooper RA, Fitzgerald SG, Cooper R, Boninger ML.(2005) Effect of a pushrim activated  power assist wheelchair on the functional capabilities of persons with tetraplegia. Archives of Physical  Medicine & Rehabilitation, 86(3):380-6.
  7. Fitzgerald, S.G., Arva, J., Cooper, R.A., Dvorznak, M.J., Spaeth, D.M., Boninger, M.L. (2003). A      Pilot Study on Community Usage of a Pushrim Activated Power Assist Wheelchair,Assist   Tech Journal, 15(2):113-119.


We would like to acknowledge Yamaha Motor Corporations, USA for providing the JWII used in this study. Funding was provided by the National Institute for Disability and Rehabilitation Research, SCI Model Systems Program (H133N000019).

Author Contact Information:

Ana E. Souza, MS, Human Engineering Research Laboratories, VA Pittsburgh Healthcare System, 7180 Highland Drive, Building 4, 2nd Floor East Pittsburgh, PA 15206, (412) 365-5561,