Quantitative evaluation of shoulder joint function to reproduce results of clinical tests by therapist

The final aim of this research is to develop a quantitative evaluation system of shoulder joint function using a three-dimensional force display robot. In this paper, we proposed quantitative evaluation methods by which the results equivalent to the results of tests by a therapist can be obtained. The quantitative evaluation methods can be installed in the robot. We focus on two shoulder joint functions. One is stability and the other is cooperativeness. Two experiments were carried out to develop quantitative evaluation methods of shoulder joint function. In the experiments, subject's forces were measured during the tests by the therapist. On the basis of the experimental results, we proposed a stability evaluation method using a regression equation of glenohumeral joint instability from the ratios between the right and the left subject's force in the initial position during abduction, external rotation and horizontal abduction motion. Moreover, we proposed a cooperativeness evaluation method by detecting two thresholds related to sustainability of subject's force.