• Christy Cheung

Digital Manufacturing in Medicine

Though not traditionally under the umbrella of digital health, 3D printing has made great strides in the most recent decade. As we come to a new normal, not just in terms of working from home, but also in socializing and spending our free time at home, I decided to explore published conference talks of interest. One group that has been on my radar is Singularity University (SU), an incredibly forward-thinking organization, with a mission to empower leaders for the future. They host a variety of conferences throughout the year and the one most relevant to healthcare would be the Exponential Medicine conference, something I would love to attend soon!

And so, during my search, I came across a presentation about 3D printing technology, given at a SU conference in 2010, by Scott Summit. Scott Summit, a designer by trade, sits on the SU faculty and his expertise lies in digital manufacturing, with a number of publications and patents in his portfolio. After watching the talk, I was amazed at where the field stood ten years ago and I can only imagine the potential of this burgeoning field in the years to come.

In a nutshell, 3D printing starts with data being fed into the computer, subsequent digital modifications based on the desired end result, then finally, digital fabrication of the object (or, in other words, 3D printing). Data can come in the form of medical images generated from CT and/or MRI scans, or images of objects taken on your everyday cameras. If you go with "budget" devices, compared to more advanced systems, you simply have to pair the data with something that can generate three-dimensional data for the purposes of printing. This is called triangulation or image correlation.

Once the data sits on your computer, you have the ability to make adjustments as you see fit. The possibilities are endless and that is the beauty of 3D printing. As Scott Summit put in his video, “complexity is free when you are doing additive fabrication.” What he means is that you can tweak one aspect of your image and the program will automatically make the right adjustments across the entire image for you, and for any number of tweaks you so choose. Now, onto the printing stage. The price of 3D printers has dropped significantly as the field has progressed, but they can still range from $3,000 too $80,000, depending on the level of sophistication you want. How they go about the actual manufacturing of your input is through an additive process; it will build the object from the base up, and do so layer by layer. If any of you have seen a 3D printer in action, that is quite literally how it works, a hypnotizing, horizontal, back-and-forth motion, as it slowly works its way up until your object is finished printing.

As you may have grasped by now, 3D printing is an easily scalable technology. It can satisfy any creative itch, but more importantly, it has clear and broad applications in the field of medicine.

Clinical use cases span from mild cosmetic procedures to critical care operations. Areas in which 3D printing quickly took off include the production of hearing aids, which captured nearly the entire market share in two years' time, and Invisalign braces, a market now worth $6.42 billion USD. Both require personalization based on the individual’s ear and teeth structure, respectively, but with a quick snapshot of these organs and a few final touches tailored to the end user, we can leave the bulk of the work to the 3D printer itself. Because of the high level of accuracy and efficiency of these printers, they can churn out large volumes of products daily, which, as you will see later, can have life-saving potential in more urgent medical settings.

Surgical operations is a specialty in which 3D printing has a great potential for disruption. Similar to the above example, the technology can be used to create prostheses and surgical instruments; however, beyond that, it can better prepare operating room physicians for the when the procedures take place. You may have seen or heard of 3D printers that generate plastic, or even stainless steel, objects, but you may be wondering, how close can this technology get to reproducing apparatus with the same makeup as the human body. Bones, by nature, are more rigid, and represent the easiest biological tissue to be produced by 3D printing, but there have been significant advances, which has seen the 3D printing of synthetic skin for burn patients, knee menisci, heart valves, and other forms of tissue and organ fabrication. Use of the latter example, however, has been limited to surgical planning or research purposes for now.

Current perspectives of 3D printing in preoperative planning are fairly positive, with studies demonstrating that using 3D-printed models specific to that patient’s organs may reduce time spent in the operating room and result in fewer complications. At the Kobe University Hospital in Japan, this has been trialled with liver transplants, in which surgeons use replicas of the patient’s surrounding organs to determine the most optimal fit of the donor liver into the recipient’s abdominal cavity, and equally important, to minimize tissue loss when operating on the donor.

If we now think ahead to the near future, we can perhaps imagine 3D printing capabilities being fully functional in the customization of synthetic organs. In many countries around the world, waiting lists for organ transplants are long and the bottleneck is finding a donor who is a tissue match. Using the patient’s own cells to create a replacement organ not only mitigates the risk of tissue rejection, but it would also eliminate the need to take immunosuppressants, which are often lifelong therapies with a whole host of adverse drug effects.

With every drug, or medicine, out there, there are associated adverse effects, which leads me to the next possible use case. The traditional model for prescribing medications is a one-size-fits-all approach. The clinician generally employs a start low, go slow approach, in which the patient will be initiated on a medication at the lowest commercially available strength. The patient may have a choice of dosage forms such as tablets or liquid, creams, patches, etc., but when it comes to the true efficacy and safety parameters of the drug for that particular patient, we are largely in the dark. Factors that can affect how patients respond to a drug include pharmacogenetics (drug-gene interactions), presence of comorbidities, therapeutic window of the drug, patient’s metabolic makeup, patient’s weight, and the list goes on. Leveraging 3D printing from a therapeutic perspective may mean printing a precise dose for the patient based on such factors. It could mean formulating a pill with multiple active ingredients and different release profiles. Sounds too complex? With numerous inactive ingredients at its disposal, a 3D printer can formulate a tablet with barriers, spaced among the various active ingredients. This would alleviate the burden of polypharmacy that many of our patients face and likely improve patient compliance overall.

These use cases may well come about in our not-so-distant future and certainly seem promising in medicine, and while 3D printing research has taken off on its own, the public and the regulating bodies have yet to grasp its role beyond existing commercial uses. Having said that, I came across this video, showing the USF Health Radiology group 3D printing nasal swabs for the purposes of COVID-19 testing. They are running at a pace of 300+ nasal swabs per batch, while the typical process for designing diagnostic tools could take years, as the group describes. All that is to say, as a society, we are beginning to recognize the capabilities of emerging technology in improving and speeding up the way we work in medicine, and 3D printing is one of those technologies that we should be aware of, and its developments, something we look forward to.

Thanks for reading, as always!

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© 2020 by Christy Cheung
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