In the industrial field, the necessity of providing some clinical data during the launching of a new medical device has noticeably increased after some recent legal evolutions. The aim of this thesis was to collect some clinical data concerning the use of a new ankle-foot orthosis in order to confirm its relevance in comparison with standard products. To formulate some reasoned hypotheses and objectively interpret these data, the knowledge of the mechanical characteristics of the studied orthoses has constituted the preliminary necessary step. After checking the feasibility and the relevance of the experimental protocol on healthy subjects, the analysis of the effects of the ankle-foot orthoses during some elementary motor tasks, which are the stance and gait, in patients (suffering from a uni or bilateral affection, of a peripheral origin, ankle dorsal flexor muscles) has been the core of our research. As a consequence, it results from this that the ankle-foot orthosesinfer some common effects and some other, specific to each model. From that moment on, in an original way, we were bound to identify, with some simple and fast ways the patients taking the larger advantage from one of the orthosis models. In addition to the necessary prerequisite which is the acceptance of the equipment by the patient, our results specify that the most adapted orthopaedic device compensates for the deficiency(ies) by restoring the motor function, without restraining the preserved abilities
