During a clinical study the AEA (Acoustic Emission Analysis) of arthritic defects in the knee joint was enhanced by the addition of kinetic measurement data. This enhanced AEA based method permits a non-invasive diagnosis and assessment of arthritic joint damage at an early stage. The diagnostic procedure includes three separate measurements that contribute in different ways to an extended diagnosis of the disease pattern [1, 2, 3]. During a series of three knee bends a force plate provides data of the ground force while a video-based gait analysis records the corresponding movement and the angles of hip-, knee-, and ankle joints. At the same time AEA detects the acoustic anomalies of damaged cartilage and the absolute angle of the system. The patterns of the kinetic data were analyzed to define the instants of time to correlate the data of the 3 measurement systems. The analysis of the force data yields a pattern with 8 phases. By means of the stance phase between the knee bends the instants of time are used to synchronize force and video based data. In the second step the synchronization of video based data was done by means of the absolute angle of the AEA system [4, 5]. The superposition of kinetic data and the acoustic emission permits a preliminary graphic representation and assessment of the measurement data. The procedure will be applied for the analysis of patients in a clinical study

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.

: In patients with arthritic knee joint defects the course of movement, the application of muscle forces and the degree of freedom of the joints of the lower limbs differs significantly from the corresponding data of a healthy proband. The enhanced acoustic-kinetic joint analysis based on AEA, ground force reaction measurements and video enhanced gait analysis permits the correlation of force data, joint angles and acoustic emission significant of defective joint cartilage regions. This diagnostic procedure permits a quantifiable and detailed non invasive diagnosis of lesion patterns in the arthritic knee joint by means of a synchronization algorithm. The AEA shows lesion signals in the first and third knee bend of the patient. The lesion signals are assigned to the joint angles and ground reaction force. Comparing the kinematical data there is a shift between the curves of the hip and the knee angle. Overall the force data represent an imbalance between the left and the right leg during the knee bends. The presentation of the three measurement systems, the method, the synchronization of the data sets and their final assessment as well as the occurring difficulties during a case of a clinical study are discussed. This would be helpful regarding further patients of the clinical study