抄録
The objective of this study is to measure the variation of patellofemoral joint contact pressure under the condition of simulating the variations of the knee flexion angle, and the thigh muscle forces during level walking, climbing and descending stairs. It will compare the results with those of the previous experimental studies in which the thigh muscle forces had been kept constant.
Using the data from the literature and applying a pure mathematical calculation, the values of tensile forces applied to the thigh muscles were determined as a function of knee flexion angle, to simulate various walking conditions. In the experiment, data was obtained by the variation of electrostatic capacity of a specially designed film inserted between the contact surfaces of the patellofemoral joint.
The experimental results demonstrated that when the thigh muscle force was kept constant, the mean contact pressure was almost uniform throughout the whole range of knee flexion, while the contact force showed a dome shape indicating the highest value at about 45° knee flexion. When the values of thigh muscle force and the knee angle simulating various walking conditions were applied, the results demonstrated that the patellofemoral contact pressures were almost constant all of the time of the stance phase of a gait cycle, also the peak values of pressure were almost equal among three kinds of walking. It was also revealed that the articular surface of contact portion where larger contact force occurs produces a smaller curvature.
The patellofemoral articular surfaces are seemingly irregular in shape, however, the complicated shapes may play an important role in moderating steep variations of patellofemoral contact pressure during walking.
