Abstract
We have developed a Knee Joint named NAL-Knee (Natural Automatic Lock Knee) for use in trans-femoral prostheses. It has a new link (referred to as a “bouncer”) under the hydraulic cylinder of the knee joint, which can move when the load is on the heel or toe. When ascending stairs and the load is on the toe, the knee is stopped from bending at arbitrary angles; when descending and the load is on the heel, it carries out a yielding function. According to this mechanism, it becomes possible for a trans-femoral amputee to ascend and descend stairs with a reciprocal gait. This knee does not require replacement of a socket or foot and does not require batteries. With a test of oxygen uptake, we proved the merit of NAL-Knee in going up and down stairs. Although going down with NAL-Knee clearly provided excellent speed and efficiency, in going up, there is a problem of individual difference and practice. Moreover, in the flat ground gait, it turned out that the device can keep up with a range of gait speeds from walking slowly to running. This is because of the use of a large oil-hydraulics cylinder, which also lessened the oil groove resistance.
