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  • Shanley Chien


How 3-D printing is changing the way doctors approach pre-operative care

In this day and age, 3-D printing seems to be the trend that doesn’t show any indication of losing steam. In fact, the technology is quickly advancing and new applications for it are being discovered every day.

For the maker community and hobbyists, 3-D printing represents a democratization of manufacturing, marking a new wave of mass personalization and offering the layman the opportunity to return to the age of working with their hands, a zeitgeist reminiscent of the Industrial Revolution.

With all the well-deserved hype and acclaim 3-D printers are receiving these days from the general public and large industries, it only makes sense that the technology has already made inroads in the medical industry, as well.

Rajesh Krishnamurthy, M.D., section chief of radiology research at Texas Children’s Hospital, has been using 3-D printing in his department since early 2011. Over the past four years, the hospital has created a total of approximately 200 models, averaging 50 models per year.

“[3-D printing] was literally the cool thing on the block. We didn’t really feel this was going to give us a huge amount of incremental value over advanced 3-D modeling, but we started seeing the impact on cases, and that’s when we realized this is going to be helpful,” Krishnamurthy said. “Now we’re focused on convincing the rest of the world that’s the case.”

What started out as a curiosity, printing musculoskeletal structures, quickly burgeoned into a relatively in-demand practice, with Krishnamurthy currently juggling five requests for 3-D printed models. Now, equipped with two in-house 3-D printers, creating model bones at Texas Children’s is child’s play.

“Skeletal structures practically print themselves,” Krishnamurthy said. “They’re very easy to extract from the CT data set, to separate from the surrounding anatomy, and to create a model out of it. It’s like printing on paper with an inkjet printer.”

Orthopedic surgeons at Texas Children’s initially wanted to experiment with different techniques to approach operating on patients with hip dysplasia, so Krishnamurthy and his team printed out a model of the pelvis and femur to physically test what angles to cut the bone to change its alignment for a better fit.

They eventually became sophisticated enough to explore printing more complicated anatomy, such as a model of a baby’s heart that did not have any arteries going to the lungs, and even a case of conjoined twins with complete fusion of the chest, abdomen and pelvis. According to Krishnamurthy, having the heart models that show the internal anatomy benefits the surgeons by helping them visualize the area they’re operating on and simulate the procedure before the patient arrives at the hospital.

“You can argue that if you’re a talented cardiac surgeon or somebody who has been doing this for a while, [you] can look at the raw data and know exactly what is going on,” Krishnamurthy said. “But when you’re dealing with such a complex situation where there are different organ systems that are abnormal, and each one needing its own specialist team, with real-time decision-making at the time of surgery, then it becomes very difficult—the coordination, the planning, the decision-making.”

The time it takes to create the models can range anywhere from one day to a week, depending on the complexity of the model.

Stephen Little, M.D., director of the Valve Clinic at Houston Methodist DeBakey Heart and Vascular Center, agreed that 3-D printing plays a valuable role in surgical planning.

“As good as our imaging is, whether it’s MRI or CT or even echo, they tend to present complicated data with a 2-D slice,” said Little, who has been working with 3-D printing at Houston Methodist for several years now. He added that their surgical procedures are becoming increasingly complex and the technology they use needs to be just as advanced. “I really see this as on the crest of the wave, where the new stuff is hitting the ground and it’s brand new. We’re using imaging techniques to see images we’ve never really seen before. We’re planning a surgery we’ve never done before. That’s where this stuff is really valuable in terms of the frontiers in medicine.”

Little’s colleague, C. Huie Lin, M.D., Ph.D., an adult congenital and interventional cardiologist at Houston Methodist, recently had a case in which a young Jehovah’s Witness patient was born with a heart defect. After her first successful surgery, she was left with a wide open, leaking pulmonary valve and needed another operation, but two centers had already turned her down because she could not take blood transfusions and they were concerned she would not make it through the surgery. When Lin was presented with her case, he had her undergo a CT scan in her hometown of South Carolina and then created a 3-D printed model based off the data.

“I didn’t want her to drive all the way out here and not be able to do anything for her,” said Lin, who used the model to more accurately study her condition, experiment with different approaches and devise a plan that was minimally invasive and required very little blood loss—all before she even stepped foot in the hospital.

“Without the 3-D printed models, we wouldn’t have been able to figure this out. We wouldn’t have been able to come up with a way to actually do the procedure in advance,” Lin said, echoing the same sentiments as Krishnamurthy and Little.

3-D printing not only allows doctors to more effectively plan surgeries to improve patient outcomes, but some doctors – such as Min P. Kim, M.D., thoracic and cardiac surgeon at Houston Methodist – are starting to incorporate the models into the teaching setting. Kim said he is interested in developing a program to educate trainees on how to perform complex surgical procedures on patient-specific 3-D printed models of anatomical structures, such as a lung, to better equip and prepare them with the skills they need for success in the operating room.

“If we can create a high-fidelity model using 3-D printing, we can provide better education opportunities for people who are operating on me when I get older,” Kim said. “One of the things we pride ourselves on is using minimally invasive technology to improve patient outcomes including robot-assisted surgeries, but a lot of the things we use are good, but it’s not perfect [in terms of] patient-specific anatomy.

“You learn how to do that operation in a model setting and then you take that knowledge to the patient side as opposed to learning your first time on the patient,” he added.

Another benefit of 3-D printed models is for the people sitting on the other side of the doctor’s desk.

“It’s great for teaching the [patient’s] parents. It’s probably the biggest value,” Krishnamurthy said. “A surgeon can basically hold the heart in their hands and tell them, ‘This is exactly what I’m going to do and these are the risks of the procedure.’”

“Before [3-D printed models], we would just use our hands like puppet motions to explain what’s happening,” Little said.

Krishnamurthy added that the parents’ understanding of their child’s case and surgical operation is dramatically altered when they see the model.

“We’ve had parents come in and say, ‘This is the first time I’ve really understood what they’re planning to do to my child,’” he said. “We should be doing this on every single case, just for one reason: parental comprehension. If we really take the phrases ‘informed consent’ and ‘informed decision-making’ seriously, and if we have this useful tool that can significantly enhance that, then why are we not doing it for every case?”

The reason this is not happening? Cost. Little, Krishnamurthy and other doctors agree that printing out 3-D models is simply too expensive, ranging anywhere from $400 to $3,000 per print, based on complexity, and is not covered by insurance. Both Texas Children’s and Houston Methodist are selective with which cases are approved to spend the time, effort and financial resources on 3-D printing, but it’s not difficult to see that the benefits will eventually eclipse the cost, especially as models become more inexpensive to produce.

“[Providing 3-D printing] is an important thing that’s going to reduce complications of the surgery, lower your length of hospital stay and improve your outcome,” Little said. “In the long run, it’s much better to pay $1,500 for a model and be in the hospital for four days less.”

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