Additive manufacturing (AM) processes have undergone significant progress in recent years, having been implemented in sectors as diverse as automotive, aerospace, electrical component manufacturing, etc. In the medical sector, different devices are printed, such as implants, surgical guides, scaffolds, tissue engineering, etc. Although nowadays some implants are made of plastics or ceramics, metals have been traditionally employed in their manufacture. However, metallic implants obtained by traditional methods such as machining have the drawbacks that they are manufactured in standard sizes, and that it is difficult to obtain porous structures that favor fixation of the prostheses by means of osseointegration. The present paper presents an overview of the use of AM technologies to manufacture metallic implants. First, the different technologies used for metals are presented, focusing on the main advantages and drawbacks of each one of them. Considered technologies are binder jetting (BJ), selective laser melting (SLM), electron beam melting (EBM), direct energy deposition (DED), and material extrusion by fused filament fabrication (FFF) with metal filled polymers. Then, different metals used in the medical sector are listed, and their properties are summarized, with the focus on Ti and CoCr alloys. They are divided into two groups, namely ferrous and non-ferrous alloys. Finally, the state-of-art about the manufacture of metallic implants with AM technologies is summarized. The present paper will help to explain the latest progress in the application of AM processes to the manufacture of implants.

With the currently available materials and technologies it is difficult to mimic the mechanical properties of soft living tissues. Additionally, another significant problem is the lack of information about the mechanical properties of these tissues. Alternatively, the use of phantoms offers a promising solution to simulate biological bodies. For this reason, to advance in the state-of-the-art a wide range of organs (e.g., liver, heart, kidney as well as brain) and hydrogels (e.g., agarose, polyvinyl alcohol –PVA–, Phytagel –PHY– and methacrylate gelatine –GelMA–) were tested regarding their mechanical properties. For that, viscoelastic behavior, hardness, as well as a non-linear elastic mechanical response were measured. It was seen that there was a significant difference among the results for the different mentioned soft tissues. Some of them appear to be more elastic than viscous as well as being softer or harder. With all this information in mind, a correlation between the mechanical properties of the organs and the different materials was performed. The next conclusions were drawn: (1) to mimic the liver, the best material is 1% wt agarose; (2) to mimic the heart, the best material is 2% wt agarose; (3) to mimic the kidney, the best material is 4% wt GelMA; and (4) to mimic the brain, the best materials are 4% wt GelMA and 1% wt agarose. Neither PVA nor PHY was selected to mimic any of the studied tissues.

Introduction: Physical 3D models known by the industry as rapid prototyping involve the creation of a physical model from a 3D computer version. In recent years, there has been an increasing number of reports on the use of 3D models in medicine. Printing such 3D models with different materials integrating the many components of human anatomy is technically challenging. In this article, we report our technological developments along with our clinical implementation experience using high‐fidelity 3D prototypes of tumors encasing major vessels in anatomically sensitive areas.Methods: Three patients with tumors encasing major vessels that implied complex surgery were selected for surgical planning using 3D prototypes. 3D virtual models were obtained from routine CT and MRI images. The models, with all their anatomical relations, were created by an expert pediatric radiologist and a surgeon, image by image, along with a computerized‐aided design engineer.Results: Surgeons had the opportunity to practice on the model before the surgery. This allowed questions regarding surgical approach; feasibility and potential complications to be raised in advance of the actual procedure. All patients then successfully underwent surgery as planned.Conclusion: Having a tumor physically printed in its different main component parts with its anatomical relationships is technically feasible. Since a gross total resection is prognostic in a significant percentage of tumor types, refinements in planning may help achieve greater and safer resections therefore contributing to improve surgical management of complex tumors. In this early experience, 3D prototyping helped significantly in the many aspects of surgical oncology planning.

The main aim of the present paper is to study and analyze surface roughness, shrinkage, porosity, and mechanical strength of dense yttria-stabilized zirconia (YSZ) samples obtained by means of the extrusion printing technique. In the experiments, both print speed and layer height were varied, according to a 2² factorial design. Cuboid samples were defined, and three replicates were obtained for each experiment. After sintering, the shrinkage percentage was calculated in width and in height. Areal surface roughness, S_a, was measured on the lateral walls of the cuboids, and total porosity was determined by means of weight measurement. The compressive strength of the samples was determined. The lowest S_a value of 9.4 μm was obtained with low layer height and high print speed. Shrinkage percentage values ranged between 19% and 28%, and porosity values between 12% and 24%, depending on the printing conditions. Lowest porosity values correspond to low layer height and low print speed. The same conditions allow obtaining the highest average compressive strength value of 176 MPa, although high variability was observed. For this reason, further research will be carried out about mechanical strength of ceramic 3D printed samples. The results of this work will help choose appropriate printing conditions extrusion processes for ceramics.

Background: Pre-surgical simulation-based training with three-dimensional (3D) models has been intensively developed in complex surgeries in recent years. This is also the case in liver surgery, although with fewer reported examples. The simulation-based training with 3D models represents an alternative to current surgical simulation methods based on animal or ex vivo models or virtual reality (VR), showing reported advantages, which makes the development of realistic 3D-printed models an option. This work presents an innovative, low-cost approach for producing patient-specific 3D anatomical models for hands-on simulation and training. Methods: The article reports three paediatric cases presenting complex liver tumours that were transferred to a major paediatric referral centre for treatment: hepatoblastoma, hepatic hamartoma and biliary tract rhabdomyosarcoma. The complete process of the additively manufactured liver tumour simulators is described, and the different steps for the correct development of each case are explained: (1) medical image acquisition; (2) segmentation; (3) 3D printing; (4) quality control/validation; and (5) cost. A digital workflow for liver cancer surgical planning is proposed. Results: Three hepatic surgeries were planned, with 3D simulators built using 3D printing and silicone moulding techniques. The 3D physical models showed highly accurate replications of the actual condition. Additionally, they proved to be more cost-effective in comparison with other models. Conclusions: It is demonstrated that it is possible to manufacture accurate and cost-effective 3D-printed soft surgical planning simulators for treating liver cancer. The 3D models allowed for proper pre-surgical planning and simulation training in the three cases reported, making it a valuable aid for surgeons.

Purpose: The use of physical 3D models has been used in the industry for a while, fulfilling the function of prototypes in the majority of cases where the designers, engineers and manufacturers optimize their designs before taking them into production. In recent years, there has been an increasing number of reports on the use of 3D models in medicine for preoperative planning. In some highly complex surgeries, the possibility of using printed models to previously perform operations can be determining in the success of the surgery. With the aim of providing new functionalities to an anatomical 3D-printed models, in this paper, a cost-effective manufacturing process has been developed. A set of tradition of traditional techniques have been combined with 3D printing to provide a maximum geometrical freedom to the process. By the use of an electroluminescent set of functional paints, the tumours and vessels of the anatomical printed model have been highlighted, providing to this models the possibility to increase its interaction with the surgeon. These set of techniques has been used to increase the value added to the reproduced element and reducing the costs of the printed model, thus making it more accessible. Design/methodology/approach: Successfully case in where the use of a low-cost 3D-printed anatomical model was used as a tool for preoperative planning for a complex oncological surgery. The said model of a 70-year-old female patient with hepatic metastases was functionalized with the aim of increasing the interaction with the surgeons. The analysis of the construction process of the anatomical model based on the 3D printing as a tool for their use in the medical field has been made, as well as its cost. Findings: The use of 3D printing in the construction of anatomical models as preoperative tools is relatively new; however, the functionalization of these tools by using conductive and electroluminescent materials with the aim of increasing the interaction with it by the surgeons is a novelty. And, based on the DIY principles, it offers a geographical limitlessness, reducing its cost without losing the added value. Originality/value: The process based on 3D printing presented in this paper allows to reproduce low-cost anatomical models by following a simple sequence of steps. It can be done by people with low qualification anywhere with only access to the internet and with the local costs. The interaction of these models with the surgeon based on touch and sight is much higher, adding a very significant value it, without increasing its cost.