FlexRim Low Impact Wheelchair Pushrim

Period of Performance: 09/13/2001 - 08/31/2002


Phase 2 SBIR

Recipient Firm

Beneficial Designs, Inc.
Minden, NV 89423
Principal Investigator


DESCRIPTION (Applicant's Abstract): Approximately 65 percent of manual wheelchair users experience upper extremity pain or injury, which can significantly impact their mobility and independence. Research has demonstrated a relationship between impact stresses on the upper extremities during wheelchair propulsion and upper extremity injury. Impact stresses occur when the hand contacts the pushrim, transmitting the stresses to the wrist, elbow, and shoulder. Current pushrim technologies do not effectively reduce these impact stresses. The FlexRim consists of an innovative flexible interface between the pushrim and wheel that reduces the impact stresses related to upper extremity injuries. In Phase I, three FlexRim concepts were developed and evaluated. The concepts allowed the pushrim to translate relative to the wheel, lowering impact forces. Use of the FlexRim did not adversely affect propulsion efficiency. In Phase II, the FlexRim design will be refined based upon Phase I results. Biomechanical evaluations of impact loading and mechanical efficiency will be conducted at the Pittsburgh Human Engineering Research Laboratories with 15 subjects. Thirty wheelchair users will evaluate the FlexRim over a three to six month period of use. Because the FlexRim reduces impact stresses related to upper extremity injuries, it serves to prevent injury, and preserve function and mobility. PROPOSED COMMERCIAL APPLICATION: The proposed wheelchair pushrim will potentially enhance the lives of all manual wheelchair users by reducing impact stresses on the upper extremities during wheelchair propulsion. The FlexRim will interface to most wheelchair wheels and will be sold as a standard wheelchair component or as an optional accessory.