SBIR-STTR Award

Manual wheelchair users have a high prevalence of repetitive strain injuries (RSJs) of the shoulder and wrist. We designed a new ergonomic pushrim (NEP) that improves the fit of a wheelchair user's hand to the pushrim. The design increases the surface area available for gripping and selectively coats surfaces with high friction materials. The Specific Aims of this project are to: (1) manufacture a new set of light-weight prototype pushrims for use for in-home trials; (2) determine the effectiveness of the NEPs in changing propulsion biomechanics after an extended period of use. Specific aim 1 will be achieved by using good engineering practice as defined by FDA and lab testing for compliance with ANSI/RESNA standards. Specific aim 2 will be achieved through a clinical trial testing the effects of the NEP on propulsion biomechanics both before and after two weeks of use. If the NEPs are found to decrease injurious biomechanics than they have the potential to prevent RSIs in manual wheelchair users. This could lead to savings in health care dollars and improved quality of life. Success in this phase 1 STTR will lead to a phase 2 STTR application and commercial development of the NEPs. PROPOSED COMMERCIAL APPLICATION: The new ergonomic pushrim (NEP) will be designed to allow retrofitting to existing manual wheelchairs. This opens a large market for the product. During initial testing using a very rough prototype of the NEP, the wheelchair users tested stated they would be interested in obtaining a NEP for personal use. As further evidence of the viability of the product the University of Pittsburgh investigated the NEP's potential and decided to proceed with a patent application.

Standard wheelchair handrims are too small to provide an ergonomic grip for the hand, there is no place to rest the thumb, and there are not separate propulsion and braking surfaces. As a result, over 60% of wheelchair users grab their tire when propelling their chair. The poor fit to the hand also makes propelling less efficient and more harmful to the arms and shoulders. The Natural-Fit Handrim was designed to directly address the shortcomings of standard wheelchair handrims. The Natural-Fit (NF) has a wider surface area for the palm of the hand and a contoured area for the thumb that sits between the rim and wheel. These dual surfaces create an improved contact area for gripping the handrim, and allow for specially coated high and low friction surfaces to maximize the efficiency of propulsion and braking. After a two-week trial use period in Phase I, subjects indicated highly favorable evaluations of the NF, and propulsion biomechanics analyses indicated that the NF facilitates more efficient wheelchair propulsion. Our Phase II efforts focus on four goals: 1) Create size options for the oval component of the handrim to better customize the fit to the hand for additional target populations, particularly women and children. 2) Make design modifications to the NF to create a new model that is specifically designed for wheelchair users who have tetraplegia. 3) Test coating alternatives for the high-friction propulsion surface to optimize effectiveness and durability. 4) Examine the long-term consequences of using the NF among various populations. Extensive testing over a 4-month trial-use period will allow us to systematically test the extent to which the NF eases stress on the shoulder, wrist, and hands, and helps to reduce the likelihood of experiencing fatigue and pain as a result of daily propulsion. For the 2 million wheelchair users in the U.S. alone, the Natural-Fit will help to reduce the pain and injury associated with the repetitive stress of daily propulsion, improve quality of life, extend the time that one can remain in a manual wheelchair, and reduce medical costs associated with secondary injuries