An Exhaustive Method for Researching Articular Orthosis Mechanisms at the Conceptual Design Stage

Abstract Population aging in recent years has increased the number of people needing orthoses to assist or rehabilitate a failing joint or limb. However, as these are a class 1 medical device, orthosis development is mainly based on companies’ empirical knowledge and this can often result in usage problems and consequently, in the most extreme cases, in the devices being abandoned. Additionally, since articular orthoses may enable a movement to be performed, this imposes additional development restrictions which should be considered during the conceptual design stage of product development. As there are limited design tools available for the conceptual design stage and existing design methods are not well adapted to the development of these demanding medical devices, the development of articular orthoses may lead to inaccurate and maladjusted concepts, ill-adapted to the user's needs, and consequently, a source of discomfort. The aim of the design method proposed here is to help the mechanical designer during the conceptual design stage by taking into account from the beginning of the development process the way articular orthoses are used in life situations and at significant moments. Additionally, based on the theory of mechanisms, concepts such as the number of components, degrees of freedom and degrees of hyperstatism can be considered. This provides an exhaustive list of possible concepts for the articular mechanism which are subsequently screened according to different criteria related to the specific limb anatomy and specific medical conditions of the user in order to optimize concept choice. On this basis, this study develops an exhaustive research method to reach a large number of possible articular mechanisms to perform the desired articular movement for a specific orthosis, also taking into account the specific human body part.