Quantitative Evaluation of Geared Manual Wheelchair Mobility in Individuals with Spinal Cord Injury: An Integrative Approach

Abstract

The purpose of this dissertation is to quantify the effects of using geared wheelchair wheels on upper extremity biomechanics and energy expenditure during functional mobility tasks in individuals with spinal cord injury (SCI). The effects of using geared wheels on hand-rim biomechanics, glenohumeral joint dynamics, and shoulder muscle activity were investigated during manual wheelchair propulsion over tiled and carpeted level-floors and up a ramp in low gear (1.5:1) and standard gear (1:1) conditions. The results for the hand-rim biomechanics indicated that regardless of the terrain, using the geared wheels in the low gear condition significantly decreased the propulsion speed, stroke distance, and hand-rim kinetics, including the peak hand-rim resultant force, propulsive moment, and rate of the rise of the resultant force. The significant decrease in the normalized integrated hand-rim propulsive moment suggests that the low gear condition is less demanding than the standard gear condition, in spite of the higher repetition during propulsion in low gear. Analysis of the glenohumeral joint dynamics and shoulder muscle activity during geared manual wheelchair propulsion over carpeted floor showed that the peak glenohumeral joint inferior force and flexion moment, as well as the shoulder flexors muscle activity, decreased significantly during the low gear condition. Manual wheelchair users with SCI were tested during the six-minute push tests on passive wheelchair rollers to evaluate the effects of using geared wheels on energy expenditure. The results indicated that using geared wheels in the low gear condition significantly increased the energy cost of propulsion and decreased the intensity of wheelchair propulsion. The findings of this dissertation demonstrate that using geared wheels in comparison to standard wheels decreases the demands on the upper extremity of manual wheelchair users, which may ultimately help preserve upper limb function leading to higher levels of activity, independence and quality of life.