Manual wheelchair propulsion is known to be an inefficient means of ambulation which has been associated with a high prevalence of upper limb injuries. Such injuries are thought to occur from a combination of repetitive movements, upper limb weakness, and inefficient propulsive technique. Hemiplegic users are particularly vulnerable to upper limb injury and pain because of being reliant on only one arm for propulsion.
Moreover, the action of manual propulsion necessitates that the hand exerts repetitive forces to the handrim in order that the hand/handrim coupling be stable to accommodate the transfer of the forces from the shoulder and arm muscles onto the handrim. This repetitive grip action may contribute to the development of upper limb repetitive strain injury. In a standard wheelchair, the handrim design has also been suggested to be one of the factors responsible for the low mechanical efficiency in manual propulsion.
This project was funded by PHG.
The aim of this study was to explore the total and regional grip forces in the hand when propelling two different manual one arm drive wheelchairs: the Neater Uni-wheelchair (NUW) and a foot steered Action3 wheelchair. Seventeen nondisabled users were randomly assigned to each wheelchair to drive around an indoor obstacle course. The Grip, a multiple sensor system taking continuous measurement of handgrip force, was attached to the propelling hand. Total grip force in each region of the hand and total grip force across the whole hand were calculated per user per wheelchair.
The Action3 with foot steering only generated significantly greater total grip force in straight running compared to the NUW and also in the fingers and thumb in straight running.
The results suggest that the Action3 with foot steering generated greater grip forces which may infer a greater potential for repetitive strain injury in the upper limb. Further work is required to explore whether the difference in grip force is of clinical significance in a disabled population.
Jon Michaelis, Neater Solutions, Buxton, UK