Suitability of the Openly Accessible 3D Printed Prosthetic Hands for War-Wounded Children

3D Printed Prostheses: The Path from Hype to Reality

3D printing has an over forty-year history but has only become popular in the last fifteen years with the expiration of restrictive patents which allowed open access and unfettered innovation by a broad range of technology developers. During the last decade interest in prostheses made by 3D printing has grown in popularity. The interest in devices has followed the Gartner Hype Cycle as 3D printing companies and associated organizations have used popular claims about 3D printed prostheses to increase their own company's popularity. These claims created unrealistic expectations which outran the early-stage limitations of the technology, causing disillusion. Currently, the industry is moving beyond these limitations and the field seems to be advancing at a sustainable rate. This article provides an understanding of the history of popular misconceptions surrounding the technology. It provides a basis for separating the myth from reality in 3D printing technology so the reader can question the popular preconceived ideas and find the real value. With a greater understanding of the past, one can apply lessons to present technology use and guide the direction of future 3D printing. This paper will also discuss lessons applicable to both high and low-income countries along with providing recommendations for the future development.

3D Printing in LMICs: Functional Design for Upper Limb Prosthetics in Uganda

Meeting the needs of persons with upper limb loss in Uganda requires an understanding of the needs and desires of the local population. The limitations of resources and accessibility for the individual gave rise to a focused design methodology for delivering a culturally acceptable solution using 3D Printing technology. A series of co-design activities were held in Uganda and provided direct feedback to drive the design of two prototypes based on acceptable aesthetics and priority Activities of Daily Living. Two terminal device prototypes were 3D printed in the UK. These can be directly attached to a standard proximal socket thread. The passive hand was printed in a flexible filament and the prehensor was printed in a durable impact resistant material. Local researchers in Uganda have similar 3D printers, filaments, and assembly hardware, which allowed for concurrent development and refinement of the prototypes. Local participation provides a rich user feedback environment to understand which elements of prosthetic device design are integral to delivering acceptable prosthetics solutions for fabrication in Uganda. 3D printing can provide a viable route to addressing the needs of the user. The proposed terminal devices are now in the process of being printed locally for field testing.

Conceptualization of an Anthropomorphic Replacement Hand with a Sensory Feedback System

In this paper, a concept for an anthropomorphic replacement hand cast with silicone with an integrated sensory feedback system is presented. In order to construct the personalized replacement hand, a 3D scan of a healthy hand was used to create a 3D-printed mold using computer-aided design (CAD). To allow for movement of the index and middle fingers, a motorized orthosis was used. Information about the applied force for grasping and the degree of flexion of the fingers is registered using two pressure sensors and one bending sensor in each movable finger. To integrate the sensors and additional cavities for increased flexibility, the fingers were cast in three parts, separately from the rest of the hand. A silicone adhesive (Silpuran 4200) was examined to combine the individual parts afterwards. For this, tests with different geometries were carried out. Furthermore, different test series for the secure integration of the sensors were performed, including measurements of the registered information of the sensors. Based on these findings, skin-toned individual fingers and a replacement hand with integrated sensors were created. Using Silpuran 4200, it was possible to integrate the needed cavities and to place the sensors securely into the hand while retaining full flexion using a motorized orthosis. The measurements during different loadings and while grasping various objects proved that it is possible to realize such a sensory feedback system in a replacement hand. As a result, it can be stated that the cost-effective realization of a personalized, anthropomorphic replacement hand with an integrated sensory feedback system is possible using 3D scanning and 3D printing. By integrating smaller sensors, the risk of damaging the sensors through movement could be decreased.

Extended Reality "X-Reality" for Prosthesis Training of Upper-Limb Amputees: A Review on Current and Future Clinical Potential

The rejection rates of upper-limb prosthetic devices in adults are high, currently averaging 26% and 23% for body-powered and electric devices, respectively. While many factors influence acceptance, prosthesis training methods relying on novel virtual reality systems have been cited as a critical factor capable of increasing the likelihood of long-term, full-time use. Despite that, these implementations have not yet garnered widespread traction in the clinical setting, and their use remains immaterial. This review aims to explore the reasons behind this situation by identifying trends in existing research that seek to advance Extended Reality "X-Reality" systems for the sake of upper-limb prosthesis rehabilitation and, secondly, analyzing barriers and presenting potential pathways to deployment for successful adoption in the future. The search yielded 42 research papers that were divided into two categories. The first category included articles that focused on the technical aspect of virtual prosthesis training. Articles in the second category utilize user evaluation procedures to ensure applicability in a clinical environment. The review showed that 75% of articles that conducted whole system testing experimented with non-immersive virtual systems. Furthermore, there is a shortage of experiments performed with amputee subjects. From the large-scale studies analyzed, 71% of those recruited solely able-bodied participants. This paper shows that X-Reality technologies for prosthesis rehabilitation of upper-limb amputees carry significant benefits. Nevertheless, much still must be done so that the technology reaches widespread clinical use.

A Semi-Automated 3D-Printed Chainmail Design Algorithm with Preprogrammed Directional Functions for Hand Exoskeleton

The problem of computerising the design and development of 3D-printed chainmail with programmed directional functions provides a basis for further research, including the automation of medical devices. The scope of the present research was focused on computational optimisation of the selection of materials and shapes for 3D printing, including the design of medical devices, which constitutes a significant scientific, technical, and clinical problem. The aim of this article was to solve the scientific problem of automated or semi-automated efficient and practical design of 3D-printed chainmail with programmed directional functions (variable stiffness/elasticity depending on the direction). We demonstrate for the first time that 3D-printed particles can be arranged into single-layer chainmail with a tunable one- or two-directional bending modulus for use in a medical hand exoskeleton. In the present work, we accomplished this in two ways: based on traditional programming and based on machine learning. This paper presents the novel results of our research, including 3D printouts, providing routes toward the wider implementation of adaptive chainmails. Our research resulted in an automated or semi-automated efficient and practical 3D printed chainmail design with programmed directional functions for a wrist exoskeleton with variable stiffness/flexibility, depending on the direction. We also compared two methodologies of planning and construction: the use of traditional software and machine-learning-based software, with the latter being more efficient for more complex chainmail designs.