Affordable Design of Total Ossicular Replacement Prostheses in Low- and Middle-Income Countries

Abstract

The objective of this thesis project is to develop an economically viable design for a titanium total ossicular replacement prosthesis (TORP) that caters to the needs of low- and middle-income countries (LMICs). The author focused on addressing the problem from the manufacturing aspect and two primary approaches, additive manufacturing (AM or 3DP) and metal forming, were selected in the literature review attached in Appendix A. One concept was generated for 3DP, utilizing selective laser melting (SLM) to fabricate a straightforward structure using Ti6Al4V. Additionally, two similar concepts, 2A and 2B, were proposed for metal forming, involving precise metal laser cutting of a two-dimensional piece and subsequent bending to achieve a three-dimensional TORP shape. Concept 2A features a fixed-length shaft, whereas Concept 2B incorporates an adjustable zigzagged shaft, aiming to obviate the need for storing multiple sizes of TORPs. These concepts were manufactured into prototypes and systematically evaluated based on predetermined assessment criteria including affordability, manufacturing process, precision, sound transmission property, and simplicity. After assessment, Concept 1 was omitted from the final solutions due to its high cost and demanding post processing steps. And Concept 2A and 2B were deemed as potential TORP designs for the costs of 3.5 and 0.9 euros, dimensional errors of 2.22 % and 2.33 %, preparation duration of 0 and 5 minutes, and the comparable performances in manufacturing process and sound transmission with the commercial products. In conclusion, the TORP designs produced by precision laser cutting were considered the more cost-effective and accessible solutions for LMICs in need of ossiculoplasty.