Comparison of upper limb joint forces during straight line and turning wheelchair maneuvers

The objective of this study was to explore the joint kinetics of upper extremities during wheelchair maneuvers. A high incidence of musculoskeletal injuries has been reported due to the overuse and high repetitive motion of wrist, elbow and shoulder during wheelchair propulsion. Studies have been conducted with the use of a dynamometer or treadmill to simulate propulsion on level or inclined surface. However, during indoor maneuvering, turning is unavoidable. Three unimpaired subjects were recruited to perform three types of wheelchair maneuvers: straight line propulsion, turning left and turning right for ninety degrees with their comfortable speed. Using the SMARTWheels and the motion analysis system (Vicon 370, Oxford), joint loadings were determined. The results showed that during turning, the side that held the wheel steady had greater peak joint reaction forces than that of the side which pushed the wheel forward. The results also indicated that the peak joint reaction forces during turning are larger than forces encountered during straight-line propulsion. In straight line propulsion, larger joint forces were found on the dominant side. However, larger joint loadings were found on the non-dominant arm holding the wheel during turning than the dominant side when the dominant hand was holding the wheel during turning. Similar results were also observed for the arms pushing the wheel forward during turning i.e. the non-dominant arm tended to exert larger efforts compared to the dominant arm.