Effect of Ramp on Joint Moment of Attendants during Manual Control of Wheelchairs

ABSTRACT

Objective@#This study aimed to predict the injury risk to attendants by simulating and analyzing the joint moment that occurs during wheelchair transportation for five different ramp ratios and five different velocities. Method: Three-dimensional musculoskeletal models and rigid structure of a standard wheelchair were developed using the AnyBody Modeling System. The ramp ratio was set to 1：6 (the steepest), 1：8, 1：10, 1：12, and 1：14 (the gentlest). The wheelchair speeds were set to 0.4, 0.5, 0.6, 0.7, and 0.8 m/s. Both the uphill and downhill movement conditions were investigated. @*Results@#Most of the joint moments that occur in the wrist joint, elbow and shoulder while driving uphill increased or decreased proportionally to the slope and speed of the ramp. However, the external moment of the wrist occurring downhill was largely influenced by the slope, and the joint moment of the shoulder showed a dynamic pattern of change in the middle of the ramp in spite of constant driving speed. @*Conclusion@#The influence that occurs during deceleration while wheelchair driving on a ramp is primarily on the proximal shoulder joint, and the influence of the release control in the middle of driving primarily causes loads on the distal wrist and forearm. A high risk of damage exists because the moment change value of the load on the shoulder joint is relatively large and increases with inclination. The increase in wrist abduction moment for deceleration while driving downhill also suggests the possibility of damage.