thesisThis thesis aims to measure th e difference in sea ted normal and sh e a r stre sse s based upon different types of wheelchair propulsion types. Previous studies have me asured biomechanical influence of wheelchair propulsion a t the u p p e r extremities. This study intends to measure the biomechanical differences a t the seating surface where wheelchair users are vulnerable to deep tissue and skin breakdowns. P ressure ulcers have been studied to form based upon a num b e r of factors, specifically: too much pressure, friction, shear, and h e a t/m o is tu re buildup. However, very little re se a rch has been performed me asuring seating stre sse s in vivo based upon wheelchair propulsion. Multiple metrics w ere used to measure the normal and sh e a r stre sse s in 10 ambulatory subjects (5 male and 5 female). To me asure normal p re ssure, p re ssu re mapping w as used. To measure the sh e a r stresses, a Molten Predia was used to measure shear. Two dramatically different wheelchair cushions w ere used: an air adjustable cushion and an HR-42 Foam block of similar size. Two different types of manual wheelchair propulsion w ere used: the traditional hand-rim wheelchair and the developmental lever-arm wheelchair. It was hypothesized th a t th e combination of the lever-arm wheelchair and the pro p e rly adjusted air cushion would significantly reduce the normal p re ssu re and sh e a r stre sse s associated with chair propulsion. The data showed a significant difference for the normal p re s su re for 9 of the 10 subjects in favor of th e air cushion over th e foam cushion. However, the sh e a r data did n o t show a significant difference for a reduction of sh e a r for any configuration of testing
