A Video-based Analysis of Tips and Falls During Electric Powered Wheelchair Driving

T.A. Corfman, R.A. Cooper, M.J. Dvorznak, M.L. Boninger, W.A. Ammer, M. Sheesley, R. Cooper, and T. Thorman

Slide 1
A Video-based Analysis of Tips and Falls During Electric Powered Wheelchair Driving

T.A. Corfman, R.A. Cooper, M.J. Dvorznak, M.L. Boninger, W.A. Ammer, M. Sheesley, R. Cooper, and T. Thorman

Slide 2
Introduction

Each Year

36,000 Wheelchair-related accidents require ER

51 Wheelchair-related deaths

Falls and tips are the reported cause (70%)

25% of wheelchair-related accidents involve EPWs

Slide 3
Introduction

Difficulty maintaining supported seated posture when subjected to external forces

Ordinary obstacles can induce these forces causing:

• Fall from chair
• Complete tip of chair

Risk increases with lack of seatbelt and/or improper footrest adjustment

Slide 4
Purpose of Study

Need to characterize these adverse EPW events

Qualitatively measure the motion/response of a test dummy

Determine if optimal legrest height and seatbelt use decreases the frequency and severity of EPW tips and falls

Slide 5
Methods
Test Dummy

50th percentile Hybrid II

Emulates subject with T8 paraplegia

Clothed to provide proper seat friction

Checked for proper starting position

Slide 6
Methods
Test Wheelchairs

Quickie P100 (Sunrise Medical Inc.)

Quickie P200 (Sunrise Medical Inc.)

Action Storm (Invacare Corp.)

Jazzy 1100 (Pride Mobility)

Slide 7
Methods
Test Wheelchairs

Seating dimensions consistent

Back rest angle consistent

Seating system/cushion

Tires and batteries

Speed calibration

Slide 8
Methods
Test Obstacles

Door threshold

Standard ADA curb-cut

Five degree ramp

50mm curb

Slide 9
Methods
Test Protocol

Each obstacle traversed

• With and without seatbelt
• Legrests too high
• Legrests properly adjusted
• Legrests too low

Slide 10
Methods
Test Protocol

Three trials per condition (216 trials/chair)

All trials videotaped

Videotapes reviewed and scored

N=no fall

L=loss of control

F=fall

T=complete tip

Slide 11
Methods
Statistical Analysis

Inter-rater reliability

Kappa measurement of agreement

Slide 12
Results

Excellent agreement between reviewers

96% of computed kappa values were valued at one (1)

No tips

Three falls

Several loss of control scores

Jazzy 1100 received no fall scores only

Slide 13
Discussion

Non-belted trials resulted in forward translation

Occurred over all obstacles in all EPWs

Greater amounts associated with improper or no legrest situations

Slide 14
Discussion

Trunk flexion noted in two driving situations in three EPWs

Action Storm, P100, P200 associated with 45 degrees trunk flexion

• upward ramp to flat transition
• perpendicular curb descent

Occurred despite proper legrest and seatbelt for Action Storm and P200

Slide 15
Conclusion

Proper legrest adjustment and seatbelt use offer the EPW user greater safety

Proper use of these devices is no guarantee

Loss of control scores recorded despite proper use

Wheelchair prescription should include driving course

Slide 16
Conclusion

No tips and only three falls may imply faster speeds and different driving conditions need investigation

These studies may help to explain previous epidemiological findings

Slide 17
Limitations

T8 paraplegia

RWD vs MWD vs FWD

Seating systems

User/device interface

Slide 18
Acknowledgements

Centers for Disease Control

Center for Injury Research and Control

Paralyzed Veterans of America

Slide 19
Thank You

The End

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Updated: March 12, 2002