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Introduction to 3D Printing in Healthcare

Abstract

In this technologically advanced decade, many cutting-edge hybrid applications, innovations, and smart utilities are being developed and implemented all over the world to improve and streamline everyday life. India’s young population is a huge draw for these ventures. The healthcare system is increasingly incorporating these technologies into its central operating model. The primary application of 3D printing in the healthcare industry is the creation of prototypes or cells for immediate clinical use. However, their use has enormous potential in Indian healthcare and research. Both current and potential applications of 3D printing in medicine fall into several broad categories. This chapter provides an overview of 3D printing with a wide range of growth potential and brings together researchers from the engineering and healthcare fields.

Keywords: 3D printing, healthcare, 3D-printing revolution engineering, additive manufacturing, healthcare industry

1.1 Introduction

In healthcare, 3D printing has yielded several advancements that, while remarkable now, might seem boring in a few years when even more spectacular breakthroughs are made. Titanium cranial implants have been 3D-printed at Walter Reed Army Medical Center [1], and a woman’s jaw was replaced with a 3D-printed prosthesis there as well [1]. In 2013, surgeons used an implant fabricated by the 3D printing company Oxford Performance Materials to replace 75% of a man’s skull [2]. After discovering a rare kind of cancer in a man’s pelvis, surgeons in the United Kingdom had to replace half of his pelvis [3]. Replacement hip cups have been made and put into tens of thousands of patients [4]. Other pharmacological treatments of 3D printing include the fabrication of bionic ears [5], attractive ears [6], and prosthetic ears. Almost all hearing aid housings are now 3D-printed [7]. In the United States alone, over 17 million teeth aligner molds are 3D-produced annually [8]. Newborns with life-threatening respiratory issues are being saved nearly routinely by tracheas and tracheal splints created using 3D printing technology [9]. It is not usually high-end, pricey 3D printers that are employed for these kinds of jobs. Surgical tracheal implants have been made using 3D printers and materials available to the general public. Custom scaffolding for a tracheal implant wa being 3D-printed by doctors at the Feinstein Institute for Medical Research using a Maker-Bot machine (about US$2,000) and PLA filament [10]. Using MakerBot machines, biodegradable medical implants made for each patient have been 3D-printed to treat bone infections and cancers [11]. There have been significant 3D printing initiatives focused on the human heart. Sabanci University in Turkey has 3D-printed aortic cells [12]. By 2023 [13], researchers at the University of Louisville hope to have successfully 3D-printed a human heart. Advanced Solutions, located out of Kentucky, plans to employ its bio assembly-Bot printer to pull it off [14]. In 2013, a high school student in California used a 3D printer to create a functional prototype of a patient-specific artificial heart [15]. Washington University in St. Louis is working on a 3D-printed membrane that can be stretched to fit over a patient’s current heart like a glove to keep it beating. Built-in sensors identify approaching issues, and electrodes shock out potentially fatal arrhythmias [16]. San Diego, California-based company Organovo is 3D-printing drug-testing tissue and is developing a 3D-printed human liver, both of which have the potential to eliminate the need for the current standard of care and the use of animals to ensure a drug’s safety and efficacy before it hits the market [17]. Some scientists are trying to develop drugs that can be printed out in 3D and used locally or at home [18]. Due to the high number of amputees in war-torn countries, such as the Sudan (where there are 50,000) and Uganda, low-cost 3D printers are being employed to create prostheses for these individuals [19]. The United States Army is also interested in applying 3D-printing technology to mitigate some of the negative effects of combat. The army and the University of Nevada are working together on a project to 3D-scan soldiers from head to toe and save the information in case a soldier loses an arm or a leg in a battle. The lightweight, inexpensive 3D-printed hand developed at Oak Ridge National Laboratory has potential applications in robotics, prosthetics, surgery, and the handling of hazardous chemicals [20]. To produce a gripping action, the finger joints receive pressurized fluid from a hydraulic pump driven by an electric motor that is housed in the palm. The fingers open and shut because of a cam driven by an electric motor, which is coupled to two master pistons through five slave pistons. The fingers’ hydraulic coupling means they will easily shape themselves to anything they grab. Facial reconstructive surgery has also benefited greatly from the use of 3D printers, including a full-face replacement performed in Belgium [21]. Reconstructing injured nerve tissue with graphene and 3D-printed scaffolds is the focus of research at Michigan Technological University [22]. Surgical guides and models are excellent examples of medical use for 3D printing. Surgeons are now 3D-printing models of a patient’s organs to study in advance of the operation. Instead of operating on a live patient, it is preferable to study models to spot anatomical irregularities and plan a course of action [23]. Doctors at Miami Children’s Hospital 3D-printed an identical copy of a 4-year-old girl’s heart so that they could practice for such a tough operation on the organ. Before functioning on an actual teen’s brain, doctors at Boston Children’s Hospital practiced on a 3D-printed variant of one. The organs of conjoined twins were successfully 3D-printed and used by surgeons at Texas Children’s Hospital to plan and rehearse the separation of the babies [24]. Chinese scientists have used a 3D-printed replica of a human body to practice separating conjoined twins sharing a digestive track. Surgeons used the model to practice cutting through bone joints and skin connections to identify the most effective method for separating newborns. Moreover, 3D-printed models are being employed to train the next generation of neurosurgeons. For medical techniques, such as knee replacement, 3D-printed surgical guidance is invaluable [25]. Software that can transform 2D x-rays into 3D models can be employed to print such instructions. Surgical guidelines and models are increasingly being printed by certain hospitals using 3D printers—for instance, Materialise, a Belgian 3D-printing startup, has set up shop in Fuwai Hospital, China’s largest cardiovascular institution. For medical uses, 3D printing appears to be a technology that evolves in waves. Researchers quickly saw the potential for CAD/CAM in the medical area, not long after its initial use in fields like mechanical engineering and design. The first patient-specific implants, such as those used to repair holes in the skull, became accessible just a few short years later. Compositional methods, such as CNC milling, were still in use at the outset, but as time went on, new additive manufacturing (AM) possibilities became popular. Selective laser sintering (SLS) and three-dimensional powder printing (also known as “additive manufacturing”) were the most common laser-based techniques utilized for biomedical applications, although they were initially restricted to metals and ceramics, respectively [26]. The emergence of fused-deposition modeling (FDM) as the first advanced manufacturing methodology based on extrusion and using polymeric materials was a crucial first step. FDM of poly(lactic acid) or polycaprolactone has been studied a lot as a way to make porous 3D scaffolds with a certain shape on the outside and inside for use in biological applications like tissue engineering. These polymers were also the earliest examples of AM using biodegradable ingredients [27]. It was possibly due to the inadequate materials that could be utilized (the majority of the initial AM machines could only perform with a minimal number of different materials) and the high expense of the machines. However, things have changed radically since a wide range of inexpensive 3D printers became accessible. Many of these printers can print in several materials, providing the versatility needed for innovations [28]. The ability to directly manufacture artificial tissues was made possible by the development of ink-jet and extrusion-based technologies that allow for the incorporation of living cells in the printing process (“bioprinting”). As a result, the last few years have witnessed a surge in the number of papers on the issue of 3D printing in medicine from academics all over the world as well as the launch of several conferences dedicated specifically to the subject.

These are the current trends that investigators see as having the most momentum:

• New biomaterials that can be used with various AM techniques are being developed.
• Increased cell integration for therapeutically relevant cell-laden structures.
• Production of highly regulated spatial patterns for the assembly of more complex structures, including those made of several materials and/or distinct types of cells.

The private sector has...