3D printing technologies are pushing the boundaries of what was once considered only possible in science fiction novels. The advances being made by engineers from around the world are contributing to a plethora of innovations that are having a major impact on conventional medical practice. Medical researchers have been able to develop solutions in the form of patient-specific prostheses and pre-operative models, tailored, corrective insoles and orthotics, new medical devices and instruments, and 3D bioprinting and tissue engineering. In this article, we will provide a brief review of some of the latest 3D printing technologies and methods that are inspiring medical research.
Pre-operative planning, prostheses, and implants
The rapid prototyping capability of 3D printing is offering the medical community a fast and cost-effective way of delivering life-altering medical interventions and solutions to patients. For individuals that require a prosthesis or implants such as a bionic hand or leg bone, 3D printing is providing a functional and affordable way to generate patient-tailored parts. The technology offers complete design freedom and rapid turn-around times.
Using high-resolution images, 3D printing is able to generate accurate models of human anatomy. Image data can be exported as a common medical file format, DICOM (digital imaging and communication in medicine), which can then be converted into a stereolithography format (STL) file. From this file, a 3D virtual model can be created. For orthopedic surgery, implants can be made from these models to replace fractured bones. Further, virtual or physical models can be used by surgeons in pre-operative planning and for teaching patients, alleviating their stress and anxiety by explaining what a procedure would entail.
Biological tissue generation
In early June of this year, scientists from the University of Colorado (UC) Denver and the University of Science and Technology in China were the first to use new material to 3D print structures that could mimic cartilage. Cartilage replacement has been a notoriously difficult hurdle to cross for scientists and healthcare professionals until now. UC Denver’s mechanical engineer, professor Chris Yakacki, led the team of researchers in using a 3D printing process called digital light processing (DLP) to create a liquid crystal resin-like substance. When exposed to UV-light the researchers observed that the substance cured and formed new bonds in several thin photopolymer layers. The final cured form constituted a strong, yet soft, and compliant elastomer. when printed as a latticed, honeycomb structure, that’s when Yakacki and his team saw that it began to resemble cartilage. Their research findings were published in the journal Advanced Materials.
In addition to utilizing this breakthrough material for cartilage replacement, Yakacki also believes there is potential for liquid crystal elastomer (LCE) to be used in the creation of a spinal cage prototype. The design of complex structures like LCE’s and the use of bioinks to help produce artificial live tissue will provide the medical research community with unique scaffolds with which to generate different components of the human body.
One particular area gaining interest by researchers and clinicians is the design of patient-specific bone grafts. Associate professor at the Department of Biomedical Engineering at Texas A&M University, Dr. Akhilesh Gaharwar, believes that developing replacement bone tissues may be an exciting prospect in the generation of treatments to help people with dental infections, arthritis, craniofacial defects, and bone fractures. This is where bioinks enter the scene. In a recent publication, Dr. Gaharwar outlines the creation of a structurally stable, biodegradable, and highly printable bioink. Garharwar’s nanoengineered ionic covalent entanglement (NICE) bioinks involve two reinforcement techniques known as nonreinforcement and ionic-covalent network. The use of these two techniques results in much more stable tissue structures.
Following bioprinting, the NICE networks form crosslinks with encapsulated stem cells to create stronger scaffolds. Within the period of three months, the cells start to produce cartilage-like extracellular matrix which calcifies to form mineralized bone. The team used next-generation RNA-sequencing technology to establish the role of nanosilicates (a component of the bioink) in inducing the formation of bone tissue. Dr. Gaharwar and his team successfully demonstrated the ability of NICE bioink to create patient-specific implantable 3D frameworks for the repair of craniofacial defects.
Medical research centered around the custom design of orthotics still bears the stigma of a high price tag and inaccessibility which can be an irritable deterrent for healthcare providers trying to do the best for their patients and a disheartening prospect for patients respectively. The revelatory story of Matej and his son Nik, shows how powerful a tool 3D printing can be in advancing medical and engineering research, efficient medical practice, and optimizing patient care.
One of the latest uses for 3D printing in the world of orthotics was the design of a cervical collar using a novel workflow for a patient with a neurological disability with no alternative means of therapy. Dr. Luke Hale and Associate Professor Dr. Deepak Kalaskar from UCL’s Institute of Musculoskeletal Sciences (IOMS) led the research which was published in Scientific Reports. The research team scanned the head and neck of the patient with a handheld scanner to generate a 3D scan mesh. This framework was then imported into Houdini software (SideFX software, version 16.5). The geometry projected onto the 3D scan conforms with it completely to create a comfortable orthosis.
Using the scan, the design of the orthosis was optimized to incorporate modifications including a porous pattern to improve ventilation. This also reduces the cost and weight of the final orthosis. Four prototypes of the cervical collar were made to accommodate patient feedback and achieve the most comfortable design. The research validated the use of using 3D printing and scanning alongside a tailored workflow for clinically beneficial outcomes while allowing for iteration, modification, and improvement of the design.
These are only some of the latest medical research advancements coming to fruition with the revolutionary technology of 3D printing. 4D printing and the use of novel bioinks for organ tissue generation are some more fascinating research prospects to look forward to in 2020.
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