Characterization of 3-dimensional net upper extremity joint forces and moments during wheelchair propulsion

Wheelchair use results in a high incidence of upper extremity pain. Little information is available concerning the forces experienced by upper extremity joint structures during propulsion. This paper presents an analysis of 3-dimensional net joint forces and moments for 3 individuals pushing a wheelchair on a dynamometer. The results show that there is a great deal of variability in joint kinetics among subjects and across joints. The shoulder experienced the largest forces and moments with particularly large components of vertical force noted. Medial-lateral forces were also relatively high. Coupled with a rapid rise in various components of the force, joint structures may be expected to fail, particularly after large numbers of strokes. The results and techniques presented here provide a framework for studying injury mechanisms at upper extremity joints related to wheelchair propulsion