Elbow moment and forces at the hands during swing-through axillary crutch gait.

Abstract

We investigated swing-through axillary crutch gait (nonweight bearing on the left lower extremity) to determine the effects of gait speed, crutch length, and handle position on the forces exerted at the hands and on the moments exerted about the elbow joints. Ten healthy subjects, skilled in swing-through crutch gait, walked at three speeds using fitted crutches, at a fixed speed with four different crutch lengths, and at a fixed speed with four different handle positions. We collected ground reaction forces that exerted simultaneously on the right crutch and motion data with a force plate and three high-speed movie cameras. A biomechanical model was developed to calculate the forces exerted at the right hand and the moments exerted about the right elbow joint. Changing gait speed from slow to the normal gait of the subject showed statistically significant effects (p less than .05) on the forces at the hand. When we changed crutch heights for the subjects, we found no significant effects on the forces at the subjects' hands. Changing handle position significantly affected the moment at the elbow. Increasing the elbow-flexion angle above 30 degrees by raising the crutch handle 1 to 2 in resulted in a 100 percent increase in elbow-extension moment. We found a correlation of .82 between actual average elbow-flexion angle and elbow-extension moment. Changing gait speed or crutch length did not affect elbow moment.