COMPARISON OF PUSHRIM KINETICS BETWEEN FOUR DIFFERENT MANUAL WHEELCHAIR PUSHRIM CONDITIONS

Aaron L. Souza, MS, Michael L. Boninger, MD, Alicia M. Koontz, MS, Brian T. Fay, MS, Rory A. Cooper, Ph.D.

University of Pittsburgh
Human Engineering Research Laboratories

Slide 1
COMPARISON OF PUSHRIM KINETICS BETWEEN FOUR DIFFERENT MANUAL WHEELCHAIR PUSHRIM CONDITIONS

Aaron L. Souza, MS, Michael L. Boninger, MD, Alicia M. Koontz, MS, Brian T. Fay, MS, Rory A. Cooper, Ph.D.

University of Pittsburgh
Human Engineering Research Laboratories

Slide 2
Introduction

Manual wheelchair users (MWU) have a high prevalence of carpal tunnel syndrome (CTS).

Factors include:

• Large forces
• Large moments

Varying wheelchair pushrim setup:

• May reduce damaging forces and moments to the hand.

Slide 3
Introduction

Shimada et al. (1997) examined 7 MWU

10 strokes on an anodized pushrim

• With fingerless gloves
• Without fingerless gloves

1.8 m/s (forces and moments)

Use of gloves displayed significantly higher motive forces and moments.

Slide 4
Introduction

Koontz et al. (1998) examined 12 MWU

• Studied the forces and moments
• 20 second trial (1.3 & 2.2 m/s)
• Anodized and vinyl-coated pushrims
• Vinyl-coated pushrims displayed a significantly decreased resultant force.

Slide 5
Purpose

The purpose of this study was to:

• Expand on the current base of knowledge.
• Examine the biomechanical changes that occur in MWU when propelling with four dissimilar pushrim arrangements.

Slide 6
Methods

Subjects:

• 48 experienced MWU (Volunteered)
• 39.17 +/- 11.71 years
• 11.72 +/- 6.74 years post operation
• 37 men and 11 women
• Spinal cord injuries of T4 level or below

Slide 7
Methods

Kinetic Data Collection:

SMARTwheel

• 3-beam system
• 3-D Force and Moments

Graphic description: a picture of the SMARTWheel describing the three-dimensional forces that are measured during testing. There is a tangential force (motive force) that is responsible for the motion of the wheelchair and two frictional forces (axial and radial).

Slide 8
Methods

Experimental protocol:

SMARTwheels placed on both sides to each individual wheelchair and secured onto a dynamometer.

Four conditions

• anodized pushrims
• anodized pushrims with gloves
• vinyl coated pushrims
• vinyl coated pushrims with a paxbac

Slide 9
Methods

Two trials (steady state) for 20 seconds at:

• 0.9 m/s (2mph)
• 1.8 m/s (4mph)

Data was weight normalized

Slide 10
Statistical Analysis

An Univariate ANOVA

A Tukey post hoc analysis was performed on significant results.

The alpha level was set at (p < 0.05).

Slide 11
Results

Combined mean peak values:

• Right/left
• Both speeds
• Highly correlated (r > 0.7)

Slide 12
Results

Graphic description: a graphical presentation of the velocity difference (Velocity - meters/second: 1.288, 1.303, 1.336 & 1.296) encountered with the four different wheelchair pushrim conditions (anodized, vinyl, vinyl with paxbac & gloves).

Slide 13
Results

Graphic description: a graphical presentation of the rate of rise difference (Rate of rise - seconds: 2.267, 2.610, 2.346 & 2.425) encountered with the four different wheelchair pushrim conditions (anodized, vinyl, vinyl with paxbac & gloves).

Slide 14
Results

Graphic description: a graphical presentation of the stroke frequency difference (Stroke frequency - Hertz: 1.146, 1.158, 1.144 & 1.354) encountered with the four different wheelchair pushrim conditions (anodized, vinyl, vinyl with paxbac & gloves).

Slide 15
Results

Graphic description: a graphical presentation of the push angle difference (Push angle - Theta: 104.548, 107.969, 104.439 & 94.521) encountered with the four different wheelchair pushrim conditions (anodized, vinyl, vinyl with paxbac & gloves).

Slide 16
Results

Graphic description: a graphical presentation of the non-planar peak moment difference (Non-planar peak moment - meters: 0.014, 0.016, 0.022 & 0.023) encountered with the four different wheelchair pushrim conditions (anodized, vinyl, vinyl with paxbac & gloves).

Slide 17
Results

Graphic description: a graphical presentation of the non-planar moment rate of rise difference (Non-planar moment rate of rise - meters/second: 0.236, 0.279, 0.318 & 0.367) encountered with the four different wheelchair pushrim conditions (anodized, vinyl, vinyl with paxbac & gloves).

Slide 18
Results

Graphic description: a graphical presentation of the resultant, tangential and radial force differences (Resultant force: 0.120, 0.121, 0.114 & 0.108, Tangential force: 0.090, 0.088, 0.077 & 0.069, Radial force: 0.055, 0.056, 0.041 & 0.035) encountered with the four different wheelchair pushrim conditions (anodized, vinyl, vinyl with paxbac & gloves).

Slide 19
Discussion

Shimada et al (1997)
Use of gloves (anodized)

• Increased tangential force (*Significant)
• Decreased radial force (Trend)

We found that the use of gloves:

• Decreased radial force (*Significantly)

Slide 20
Discussion

Koontz et al (1998).

Use of vinyl-coated pushrim displayed:

• Resultant force (*Significant)

We found that with the use of gloves:

• Resultant force (Trend)

Slide 21
Conclusion

Gloves:

• Decrease damaging forces
• Decrease sensation of pain (Padding)
• Provide better coupling between hand and pushrim.

More biomechanical studies!

Slide 22
Acknowledgements

Department of Veteran Affairs
National Institutes of Health (NIH)
Paralyzed Veterans of America (PVA)
Eastern Paralyzed Veterans of America (EPVA)

The End

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Updated: March 22, 2002