Wrist kinematic characterization of wheelchair propulsion in various seating positions: implication to wrist pain.

OBJECTIVE: To investigate wrist kinematic characterization at various wheelchair seat positions.
DESIGN: A comparative study using a repetitive measures design.
BACKGROUND: People who use wheelchairs often sit on pressure-relief cushions, increasing the seat height. Wrist kinematic properties during manual propulsion could be altered. Wrist kinematics from a clinical perspective has not been previously investigated. This study characterizes wrist kinematic performance of subjects during manual wheelchair propulsion at various seat positions.
METHODS: Subjects for this investigation were 11 people with disabilities who use wheelchairs. Combinations of horizontal positions of the rear wheel and vertical seat height were evaluated. Consecutive EMG, wrist joint angle, and trigger signals were collected.
RESULTS: Altered seat height resulted in significant changes to temporal phases and wrist kinematic parameters; however, altered horizontal seat position did not cause significant variations. For all seat positions investigated, wrist extensor and flexor EMG signals maintained a similar level of contraction.
CONCLUSION: During wheelchair propulsion, seat height was found to be a critical factor affecting the temporal parameters of movement and wrist kinematic properties of the subjects. Wrist joint angles and wrist flexion-extension range of motion all varied according to seat height. Observations and statistical analysis of the results provided useful information; however, an ideal seat position was not indicated. RELEVANCE: Study results have enhanced our understanding of wheelchair design, and should aid in development of future designs. In addition, the results may provide a strategy for dealing with the onset of arm/wrist pain and the prevention of carpal tunnel syndrome and other soft tissue injuries in people who use wheelchairs.