A part of the work of a physiotherapist consists on analysing its patients’ motion capacities. In the case of motion analysis, some difficulties can hinder the evaluation process: attention can be diverted, situations can be delicate to evaluate. The consequence is an inter-individual variability and uncertainty during the evaluation. New motion sensors make it possible to record and analyse the motions with another point of view. Those tools can be used to help in the capture, but the restitution of the recorded information needs to be adapted to the user knowledge with the aim to be interpreted. In this paper, the authors propose to put the user at the center of this tool in an application of the UCD principle by proposing a method to return information based on a Knowledge Based structure. The restitution modules and tools are constructed on different levels of knowledge represented in a knowledge-based expert system. The knowledge has been structured into 4 levels (from the most factual to the most abstract) and were linked to 4 levels of restitution (from the most textual to the most graphical). A casestudy using the assessment scale “Motor Function Measure” is presented.