Relation between median and ulnar nerve function and wrist kinematics during wheelchair propulsion.

OBJECTIVE To investigate the relation between median and ulnar nerve health and wrist kinematics in wheelchair users. DESIGN Case series. SETTING Biomechanics laboratory and electrodiagnostic laboratory at a Veterans Health Administration medical center and a university hospital, respectively. PARTICIPANTS Thirty-five people with spinal cord injury who use manual wheelchairs. INTERVENTION Subjects propelled their own wheelchair on a dynamometer at 0.9 and 1.8m/s. Bilateral biomechanic data were obtained by using force and moment sensing pushrims and a kinematic system. Bilateral median and ulnar nerve conduction studies were also completed. MAIN OUTCOME MEASURES Wrist flexion, extension, radial and ulnar deviation peaks, and ranges of motion (ROMs) as related to median and ulnar motor and sensory amplitudes. A secondary analysis included peak pushrim forces and moments and stroke frequency. RESULTS There was a significant, positive correlation between flexion and extension ROM and both ulnar motor amplitude (r=.383, P<.05) and median motor amplitude (r=.361, P<.05). CONCLUSIONS Contrary to our hypothesis, subjects using a greater ROM showed better nerve function than subjects propelling with a smaller ROM. Subjects using a larger ROM used less force and fewer strokes to propel their wheelchairs at a given speed. It is possible that long, smooth strokes may benefit nerve health in manual wheelchair users.