Goal: This paper aims to provide an overview with quantitative information of existing 3D-printed upper limb prostheses. We will identify the benefits and drawbacks of 3D-printed devices to enable improvement of current devices based on the demands of prostheses users. Methods: A review was performed using Scopus, Web of Science and websites related to 3D-printing. Quantitative information on the mechanical and kinematic specifications and 3D-printing technology used was extracted from the papers and websites. Results: The overview (58 devices) provides the general specifications, the mechanical and kinematic specifications of the devices and information regarding the 3D-printing technology used for hands. The overview shows prostheses for all different upper limb amputation levels with different types of control and a maximum material cost of $500. Conclusion: A large range of various prostheses have been 3D-printed, of which the majority are used by children. Evidence with respect to the user acceptance, functionality and durability of the 3D-printed hands is lacking. Contrary to what is often claimed, 3D-printing is not necessarily cheap, e.g., injection moulding can be cheaper. Conversely, 3D-printing provides a promising possibility for individualization, e.g., personalized socket, colour, shape and size, without the need for adjusting the production machine. ä IMPLICATIONS FOR REHABILITATIONUpper limb deficiency is a condition in which a part of the upper limb is missing as a result of a congenital limb deficiency of as a result of an amputation. A prosthetic hand can restore some of the functions of a missing limb and help the user in performing activities of daily living. Using 3D-printing technology is one of the solutions to manufacture hand prostheses. This overview provides information about the general, mechanical and kinematic specifications of all the devices and it provides the information about the 3D-printing technology used to print the hands. ARTICLE HISTORY

Additive manufacturing, also known as 3D printing, has begun to play a significant role in the field of medical devices. This review aims to provide a comprehensive overview and classification of additively manufactured medical instruments for diagnostics and surgery by identifying medical and technical aspects. Methods: A scientific literature search on additively manufactured medical instruments was conducted using the Scopus database. Results: We categorized the relevant articles ( 71) by considering the novelty of each proposed instrument and its clinical application. Then, we analyzed the relevant articles by examining the reasons behind choosing additive manufacturing technology to produce instruments for diagnostics and surgery. Possible customization (27%) and Cost-effectiveness (23%) were the main reasons expressed. Technical specifications of the additive manufacturing technology and the material used were also analyzed, and a tendency of using material extrusion technology (35% of the applications) and polymeric materials (86% of the applications) was shown. Conclusions: Additive manufacturing is opening the door to a new approach in the production of medical devices, which allows the complexity of their designs to be pushed to the extreme. However, we found that technical limitations need to be tackled and important aspects such as sterilization or debris contamination are still not considered to be relevant factors during the design and fabrication process. Keeping in mind the challenges of such a new field, additive manufacturing technology can be considered as a great opportunity to provide easy access to healthcare in developing countries as well as an important step toward patient-specific medicine.

The Delft Institute of Prosthetics and Orthotics has started a research program to develop an improved voluntary closing, body-powered hand prosthesis. Five commercially available voluntary closing terminal devices were mechanically tested: three hands [Hosmer APRL VC hand, Hosmer Soft VC Male hand, Otto Bock 8K24] and two hooks [Hosmer APRL VC hook, TRS Grip 2S]. The test results serve as a design guideline for future prostheses. A test bench was used to measure activation cable forces and displacements, and the produced pinch forces. The measurements show that the hands require higher activation forces than the hooks and 1.5-8 times more mechanical work. The TRS hook requires the smallest activation force (33 N for a 15 N pinch force) and has the lowest energy dissipation (52 Nmm). The Hosmer Soft hand requires the largest activation force (131 N for a 15 N pinch force) and has the highest energy dissipation (1409 Nmm). The main recommendations for future prostheses are the following: (1) Required activation forces should be below the critical muscle force (*18% of maximum), to enable continuous activation without muscle fatigue; and (2) hysteresis of mechanism and glove should be lowered, to increase efficiency and controllability.

Abstract-Quantitative data on the mechanical performance of upper-limb prostheses are very important in prostheses development and selection. The primary goal of this study was to objectively evaluate the mechanical performance of adultsize voluntary opening (VO) prosthetic terminal devices and select the best tested device. A second goal was to see whether VO devices have improved in the last two decades. Nine devices (four hooks and five hands) were quantitatively tested (Hosmer model 5XA hook, Hosmer Sierra 2 Load VO hook, RSL Steeper Carbon Gripper, Otto Bock model 10A60 hook, Becker Imperial hand, Hosmer Sierra VO hand, Hosmer Soft VO hand, RSL Steeper VO hand, Otto Bock VO hand). We measured the pinch forces, activation forces, cable displacements, mass, and opening span and calculated the work and hysteresis. We compared the results with data from 1987. Hooks required lower activation forces and delivered higher pinch forces than hands. The activation forces of several devices were very high. The pinch forces of all tested hands were too low. The Hosmer model 5XA hook with three bands was the best tested hook. The Hosmer Sierra VO hand was the best tested hand. We found no improvements in VO devices compared with the data from 1987.

As additive manufacturing of polymeric materials is becoming more prevalent throughout industry and research communities, it is important to ensure that 3D printed parts are able to withstand mechanical and environmental stresses that occur when in use, including the sub-critical cyclic loads that could result in fatigue crack propagation and material failure. There has so far been only limited research on the fatigue behavior of 3D printed polymers to determine which printing or material parameters result in the most favorable fatigue behavior. To better understand the effects of the printing technique, printing materials, and printing parameters on the fatigue behavior of 3D printed materials, we present here an overview of the data currently available in the literature including fatigue testing protocols and a quantitative analysis of the available fatigue data per type of the AM technology. The results of our literature review clearly show that, due to the synergism between printing parameters and the properties of the printed material, it is challenging to determine the best combination of variables for fatigue resistance. There is therefore a need for more experimental and computational fatigue studies to understand how the above-mentioned material and printing parameters affect the fatigue behavior.