Introduction

In the USA an estimated 2.2 million people currently use wheelchairs for their daily mobility (Americans with Disabilities, 1994; Shalala et al., 1996). It is likely that more than twice that number use wheelchairs at any given time to augment their mobility. Worldwide, an estimated 100–130 million people with disabilities need wheelchairs, though less than 10% own or have access to one (New Freedom Initiative Act, 2001). While these numbers are staggering, experts predict that the number of people who need wheelchairs will increase by 22% over the next 10 years (Department of Veterans Affairs, 2002). The leading cause of disabilities in the world can be attributed to landmines, particularly in developing nations, leading to 26,000 people injured or killed by landmines each year (Department of Veterans Affairs, 2002).

Prevention of secondary conditions

Wheelchair and seating biomechanics research includes studies to prevent secondary conditions due to wheelchair and seating use (e.g., pressure ulcers, adverse changes in posture, repetitive strain injuries), and to reduce the incidence of accidental injuries (e.g., injuries from wheelchair tips and falls, injuries from motor vehicle accidents).

Upper extremity repetitive strain injuries

Studies have shown that manual wheelchair propulsion efficiency is between 5% and 18% depending upon the style of the wheelchair and the fit to the user (Bayley et al., 1987; Curtis et al., 1995; Nichols et al., 1979).