Development of a test rig for the diagnosis of arthritic knee joint defects in the case of lower extremity amputees in orthopaedic technology

Abstract

If the alignment of a leg prosthesis is inadequate there will be the danger of arthritic defects occurring in the preserved knee joint. Acoustic-kinetic joint analysis in orthopaedic technology allows monitoring of the knee joint of an amputee after the alignment of a leg prosthesis and to recognize early joint defects resulting in adaptation of the alignment of the prothesis. A test rig was developed which includes acoustic emission analysis of the knee, video-based gait analysis, ground reaction force measurement and the measurement of the holding forces of the hands. During the examination a subject must do 3 one-legged knee bends during 10 sec with the preserved leg. To support the subject two grab handles were fixed with force sensors to a frame. A series of 6 measurements were recorded with breaks of 2 min. The recorded forces of the leg show a double hump pattern during the knee bend. The rising edge of the flexion phase was not uniform. The forces show no conclusive uniform pattern. The fitness of the probands acts as an indicator for the pattern of the force signals. The signals of the measurements show the necessity of the support for both hands to execute a one-legged knee bend. The understanding of the 3 measured forces is important for the arthritic diagnosis of the knee joint.