Rate and range of knee motion during ambulation in healthy and arthritic subjects.

The purpose of this study was to determine the relationship between gait velocity and rate and range of knee motion, during ambulation, for healthy and arthritic subjects. The arthritic subjects had either rheumatoid arthritis or osteoarthritis, and all were tested before and after total knee replacement. Healthy subjects ambulated at an average velocity of 80 m/min and demonstrated knee flexion and extension rates of 344 degrees/sec and a range of knee motion of 60 degrees. Gait velocity correlated with rates of knee flexion and extension and range of knee motion. Arthritic subjects ambulated at velocities less than those of healthy subjects ambulating at free speed. Arthritic subjects accordingly demonstrated reduced knee flexion and extension rates and range of knee motion. When compared with healthy subjects ambulating over a comparable gait-velocity range, the arthritic subjects demonstrated reduced rates and range of motion in most instances. We discuss implications for therapeutic intervention to increase gait velocity for arthritic subjects.