January 1, 2017 by admin 0 Comments

A start-up project to create customised 3D-printed hand prostheses affordable in developing countries

Authors
Rafael R. Torrealba, Samuel B Udelman, Arturo J Rivas, Fernando J Carvalho
Abstract
Purpose: Prosthetic devices are expensive in developing countries, regardless of whether they are for lower or upper limbs. However, in the latter case, the prostheses are not much demanded in structural terms and that is why 3D-printing using common polymeric materials as PLA or ABS may be used to produce these in a clean, relatively fast and affordable way. In particular, the present paper is aimed at creating customised 3D-printed hand prostheses at an affordable price in Venezuela, a developing country. The idea is to approach this task by combining the designs of some similar initiatives abroad, and the authors' know-how in the P&O field, as well as in mechanical design and 3D-printing. Method: In general terms, this work looks to give a holistic statement of the problem, presenting an ongoing local initiative to solve it, and sharing some concluding remarks on the outcomes of this work besides a prospective on what the near future might bring. For this, the paper was structured in accordance with the methodology applied, covering the following issues: research introduction, background contextualisation, mechanical design and manufacturing of the hand, a case study, cost analysis, alternatives to give sustainability to the project, and finally, conclusions and prospective view. Results: A complete customised 3D-printed prosthesis was created, consisting of both arm and hand, for a 13-year-old male child disarticulated at the elbow. This allowed, on the one hand, to present the process of design and manufacturing of the prosthesis, furthermore involving the P&O criterion of qualified technicians to fit and evaluate its performance preliminarily, and on the other one, to analise the resulting cost structure of this initiative in a developing country, such as Venezuela, at the time that several alternatives are introduced in order to make this start-up viable. Conclusions: Some changes in the design of the hand prosthesis developed so far are needed, in order to make it really functional, and to automate the process of adapting the hand design to a particular patient requirements, until the subsequent manufacture and mounting of the device. Using 3D-printing for creating hand/arm prostheses brings affordability to this kind of devices in a significant measure, but it is made clear that the use of such technology by engineers to create prostheses must be accompanied by the skilled job of prosthetists. Likewise, several alternatives, such as making alliances with healthcare institutions, launching community service programs through universities, besides looking for private investment and public funds, must be explored in order to raise the budget required to make this start-up sustainable in time. Finally, as a prospective conclusion, it is remarked that the development initiated with this work is able to incorporate future advancements in the technology of artificial hands.

July 1, 2016 by admin 0 Comments

Development of design and manufacturing methodology to create preformed custom prostheses for cranioplasty applications

Authors
Natalia Leon, Leandro I. Martínez, Rafael R. Torrealba, Samuel B. Udelman
Abstract
Polymethyl methacrylate (PMMA) preformed custom implants for cranioplasty applications have two main purposes: to restore the protection normally given by the cranium to the brain, and to improve the appearance of head surface after a traumatism or malformation. These implants have advantage such as material cost decrease, compared with other materials as titanium, hard tissue replacement (HTR) and polyether ether ketone (PEEK), and risk reduction related to tissue necrosis and residual monomer release to the bloodstream, as consequence of “in vivo” reactions. The aim of this work is to implement a process to create PMMA preformed custom implants, as an accessible alternative in the venezuelan economic context, made possible by applying a suitable design and manufacturing methodology. In Venezuela, the majority of cranioplasties are made either by implantation of titanium meshes or via “in vivo” reactions with PMMA. In such sense, we are introducing a more holistic methodology which not only creates the PMMA implant, but also establishes the key channels between a highly technical engineering staff and the medical system of our country, mainly the neurosurgeons that execute the cranioplasties, looking to adapt the implants design to the medical requirements as much as possible, and as a consequence, reducing the surgical time compared with prosthetic implants molded during the surgery. This process is designed as follows: first, the patient medical data is obtained from the computed tomography (CT) images processed in Mimics® and 3-matic® to generate the bone structure to be treated and design the corresponding implant to meet the neurosurgeon’s specific requirements. Then, the implant positive mold is 3D-printed in polylactic acid (PLA) using fused deposition modeling (FDM) technology, which reduces costs in comparison with others rapid prototyping processes and builds more accurate pieces. Using this positive mold, a negative mold is created based on a silicone rubber that cures at room temperature, with negligible shrinkage to avoid changes on the mold dimensions. This silicone was chosen to guarantee an exact reproduction of the positive implant details. The 3D-printed implant is removed from the mold cavity and filled with a PMMA based bone cement to generate the final implant. Compared with other two-steps methods for mold fabrication, the one presented here allows getting the most accurate thickness for the implant. After the PMMA cement has cured into such a silicone mold, the customized PMMA implant must be sterilized with ethylene oxide and is ready to be fitted and secured on the patient cranium during the cranioplasty