Journal of the Society of Biomechanisms

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Experimental results are described to clear the function of bouncing-type prosthetic knee joints during the stance phase. The moments and forces acting on the hip, knee and ankle joints of prosthetic side in the level walking of three active young amputees were measured by instrumented pylon installed in the shank part and flexible electro-goniometer attached on the hip, knee and ankle joints. From these data, the bouncing knee joints showed the following characteristics 1) The hip joint angular displacement of prosthetic side in the early stance phase was very close to that of normal subject. This shows that the vertical displacement of the gravity center decreased compared with other knee joints. 2) The inclination of the first peak of the compressive force acting on the shank was smaller than other knee joints, and this showed more absorption of the impact force at heel contact compared with other knee joints. 3) The period of the dorsi-flexion of ankle joint is shorter than other knee joints. This shows that foot-flat occurs earlier and increases the stability of stance phase period compared with other knee joints. 4) The positive power of the knee joint in the stance phase was very smaller than that of normal subject and had poor effect on the push-off motion.

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The purpose of this study was to investigate motion patterns for elderly people stepping over obstacles with a videography by comparing with those of the young. Crossing speed, step length, and step frequency of the elderly were significantly smaller than those of the young. With an increase in obstacle heights, crossing speed and step frequency decreased in the elderly, but there was no significant change in those of the young. With increased obstacle heights, the elevation of the lead leg increased in both groups, depending more on the elevation of the thigh and the flexion of the hip and ankle joints for the elderly, and the elevation of the shank and knee flexion for the young. In the elderly, the range of motion for the upper arm was significantly smaller than that of the young, and the forward lean of the trunk increased after landing of the lead leg at high obstacle. This may have made the clearance of the trail leg easier.

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