Design Method to Structure Orthosis Design: Camptocormia Postural Brace Case Study.

Ricardo Duarte,Antonio Ramos,Jean-Pierre Nadeau,Michel Mesnard

doi:10.1155/2019/3513947

Abstract

The orthosis is considered a class 1 medical device which often originates from a nonstructured development process. As these devices are mainly developed by small- and medium-sized enterprises, with no standard research method, the result can be an unadapted device which may not respond to the user's needs and which in the short term may be abandoned. One way to solve this problem is to define and apply standard rules and procedures throughout the development/design process. Although methodologies may solve the “empiricism” in orthosis design problems, these design strategies are not applied during orthosis development due to the particularities of this field and the difficulties in linking the required knowledge and the actors that may be present during the orthosis development. The objective of this work is to develop a methodology to structure the orthosis design process that takes into account both the device life cycle and the different stakeholders involved in the design process. A case study was used to validate the proposed methodology. It was applied to the development of an orthosis to treat a specific postural disorder called camptocormia, also known as bent spine syndrome. This disorder is characterized by the anteroflexion of the trunk and especially affects elderly people. Contrary to scoliosis, the characteristics of camptocormia are not permanent, which means that the patient is able to straighten his posture. A postural brace is used to treat this disorder which enables the patient to redress and maintain the correct upright posture of the trunk.

Highlights

By taking into account whether or not there is a mechanism to connect the several supports of the orthosis and which displaces one with respect to the other, orthoses can be divided into two groups: orthoses with no mechanism (ONM) and orthoses with mechanism (OWM)
E rst stage is divided into four phases where the designer de nes the following: (i) e number of solids included in the kinematics chain (ii) e kinematics between the supports (iii) e dependency between translations and rotations (iv) e usefulness of considering additional degrees of freedom in the kinematics chain to what is necessary in order to establish a nonessential DoF for the limb (v) e advantage of having superabundant degrees of freedom
The designer de nes the way to suppress the degrees of freedom (DoF) of the mechanism, blocking it, which locks the orthosis in its prescribed treatment position

Summary

Materials and Methods

Using the breakdown of the design process proposed by Pahl and Beitz [7, 8] as a base (task clari cation, conceptual design, embodiment design, and detailed design), it was possible to develop a new design methodology for the development of the orthosis. E rst stage of the proposed methodology corresponds to task clari cation, which may include the de nition of the orthosis stakeholder, the orthosis typology, and the orthosis life situations. E mechanical designer checks the speci cations of the medical domain, and with the technical department, he develops the concept and the functional prototypes in the early design stages. Later, both the actors produce the orthosis. Life situations correspond to the direct and indirect interactions between the user and the device when the orthosis is in use [11] Based on this de nition, the orthosis usage cycle can be divided into ve distinct situations (Figure 3). E methodology will be explained of this paper and the nal overview presented at the end of the Materials and Methods section

Stage One

Stage Two

Stage Four

Stage Five

Stage Six