Design and Implementation of a Polar-type 3D Printer for Highly Optimised Manufacturing of Prosthetic Sockets in LMICs

t is estimated that approximately 57.7 million people worldwide live with limb loss [1]. These are mostly con- centrated in low- and middle-income countries (LMICs), where healthcare provision is limited and the skilled workforce required to manually produce prosthetic sock- ets is too small to meet this huge clinical need. Manufac- turing prosthetic sockets using conventional casting is a time consuming and labour intensive process, involving the patient making multiple visits to the clinic over a number of weeks [2]. Once cast, it can take up to a day for a technician to manually produce a customised socket. There is therefore an urgent need for a fast, highly automated, and low cost solution to the manufacture of personalised prosthetic sockets. 3D printing is often proposed as a way of meeting these objectives [3]. A 3D printer can produce one-off objects with limited setup time and cost, from affordable and readily available materials, with virtually no human intervention between the start and end of the process [4]. Previous research has also investigated the use of 3D scanners to automatically generate sockets from the geometry of a residuum, further reducing the workload of skilled technicians, increasing throughput [5]. Despite these advantages, a number of technical chal- lenges have prevented the widespread use of 3D printed prosthetic sockets in LMICs. The limited mechanical strength of 3D printed sockets has been previously highlighted [6], Firstly, the mechanical strength of 3D printed pros- thetic sockets has been called into question by studies that have observed catastrophic failures of 3D printed sockets [6], and even those that have been able to meet the ISO 10328 standard for mechanical durability have required significant iteration before meeting this requirement [7]. Additionally, whilst much faster than manually produced sockets, current 3D printers can still take up to 48 hours to produce a full sized, lower limb socket, meaning that a large and expensive print farm would be needed show any meaningful benefit [8].