The Role of Knee Joint in Passive Dynamic Walking

During walking, the knee joint with the greatest range of motion in human body, has received limited attention in gait studies. Previous studies have focused on how loading and knee range of motion are affected by conditions such as arthritis, obesity, and anterior cruciate ligament rupture, with little emphasis on the knee’s direct impact on gait dynamics. This study investigated how knee flexion–extension function influences gait patterns. To examine the role of knee joint, Passive Dynamic Walking models were developed with and without knee. These models consist of five masses and four links and integrate anthropometric human data. The results showed that knee flexion–extension enhances gait stability at higher speeds but decreases it at lower speeds. The knee joint separates the thigh and calf masses, creating angular momentum within the swing leg and significantly increasing the change in angular velocity. However, other gait state variables, such as support leg angle, angular velocity, and swing leg angle, showed no significant differences when compared to compass gait model. Furthermore, the knee's flexion–extension function caused a phase shift in linearized stability dependent on the slope angle. This study provides insight into the knee joint’s role in gait, particularly its impact on linearized stability across different slope angles.