3D Molds Enable New Standard of Care for Surgery

By Matt Phillion

What if surgeons could practice an upcoming, particularly challenging surgery on a realistic model that looks and feels like an actual patient? This type of rehearsal is now a reality using a technique that mimics real human tissue.

“The entire process started with one patient,” says Ahmed Ghazi, MD, FEBU, MHPE, a Rochester, New York–based urologist who spearheaded the technique’s development.

He and his team had previously been working with the concept of developing organ “phantoms” using a combination of two emerging technologies: 3D printing and polymer molding.

“3D printing allows you to take a patient’s CT scan and convert it into a computer design that can then be 3D printed,” says Ghazi. “3D printing has transformed several manufacturing industries, as rather than having [to subtract] material from a block to create the desired object, you instead build from the ground up.”

3D printing technology in healthcare has allowed fabrication of perfect replicas of patients’ organs based on their imaging. But those models could only serve as visual aids since no existing 3D-printing polymer could replicate the mechanical properties of human tissue, Ghazi explains. “It doesn’t give the feel the surgeon would get from surgery,” he says.

And so, his team evolved the process. Rather than printing the organ, they now print negative molds and then inject into those molds a versatile hydrogel that provides the necessary “feel.”

“The hydrogel is a powder, and it’s mixed with a multitude of formulations—it can be as hard and tough as muscle or soft and fluffy as soft fat,” says Ghazi. “What we did was take it a next step further, developing a sophisticated molding process where we start with the innermost part of the organ we wanted to create—the kidney, for example—and take each layer and register into the mold of the next layer (just like Russian dolls), so you’d have the consistency of every layer in the final kidney phantom since each layer was molded independently. This allowed us to create and incorporate hollow vessels that would bleed, so in addition to the realistic feel the phantoms would also bleed the same way for a truly immersive platform.”

Ghazi and his team also adds the surrounding organs that the surgeon will interact with during the actual surgery, almost recreating the entire patient torso from their imaging. This allows surgeons to complete the full procedure, from the incision to the removal of the specimen and closure. Ghazi calls it a surgical rehearsal platform.

In the beginning, they worked with open-source software making generic organs for training. But the team got started with their current technique when a patient came to Ghazi’s attention with a very complex renal tumor. With most renal tumors, the surgeon will attempt to remove only the tumor while preserving the healthy portion of the kidney, but in this patient’s case two previous urologists agreed that the only way to remove the tumor was to remove the entire kidney—reconstructing the remaining tissue into a functioning organ would simply be too difficult.

“We didn’t have the resources for that right at that moment,” Ghazi says. But his team didn’t settle for shrugging their shoulders. “There was software we needed to complete this task—and we were able to collect funds from donors to get that software, replicate the CT scan, and make the model.”

Ghazi was able to practice the surgery in his operating room with his entire team not once but five times before the live surgery, trying different approaches and techniques to remove the entire tumor while leaving the healthiest kidney tissue behind that was connected to the required blood supply and urine drainage to independently function in real time.

“With the kidney, you are cutting against the clock,” says Ghazi. “For this procedure to be successful, the surgeon has to temporarily block the blood supply to the kidney to prevent the patient from bleeding out when cutting into the kidney. We know from the kidney transplant literature that kidneys can only survive for 30 minutes with no blood. So part of these rehearsals was to also test the time execution for the best results.”

They were then able to demonstrate these results to the patient, with kidney phantom in hand, and discuss the various options and outcomes.

“We usually can only give the possible predictions,” says Ghazi. “ ‘This is the likely outcome, but there is no solid outcome. This is the expected blood loss,’ etc. But with this approach, we were able to keep going back and forth until we found a sweet spot for both preserving the most viable kidney tissue [and] ensuring no tumor was left behind to grow all this within the 30-minute time limit. This patient is now a five-year survivor of cancer with good kidney function.”

The simulation capabilities enable surgeons to predict better outcomes before the patient is in the operating room. “We can measure twice, cut once,” says Ghazi. “To me it was an epiphany.”

Additionally, the model enables the surgeon to look back at the simulated patient post-rehearsal and immediately realize how they can improve the surgery, which is impossible to do with a live patient. “Even if, God forbid, they expire, we’re not able to do this as tissue changes,” he says.

The process recreates almost half the entire patient body, which enables the surgeon to spot minute details—loose sutures, cutting too close to a vital structure—and then perform the procedure again and again until they get it perfect. “The way to perfect practice, if you may,” says Ghazi. “It’s almost a dress rehearsal, so during the actual performance you know you’ve crossed all your t’s and dotted all your i’s.”

Better outcomes through practice

The team has created about 150 models so far and has seen quantifiable quality improvements with their use. Patients whose surgeons used the models were six times less likely to see complications than patients whose surgeons went without the models, and experienced a two-day decrease in post-surgery hospital stays. They also, more importantly, saw less cancer left behind.

“This kind of technology improves patient outcomes not because it improves the surgeon’s ability, but because it takes out a lot of the guesswork related to a complex thing like surgery,” says Ghazi. He explains that surgeons often don’t learn the details of a patient’s anatomy until they’ve begun the actual procedure, requiring them to think and course-correct quickly. “Sometimes it feels like building a plane in the sky.” Having a model of their patient’s exact anatomy beforehand is therefore extremely helpful.

Surgeons with a vast amount of experience have a library of patients in their working memory, Ghazi says. If they’re faced with a patient presentation that resembles one of their previous cases, they’ll be able to recall that case in their mental library, predict what is likely to happen with the current patient, and go in with an informed game plan. A surgeon with this knowledge  is called a true expert of experts, but the mindset takes decades to develop.

“The experience I got from these models, 150 models is more like a thousand patients,” says Ghazi. “There’s a lot of missed complications that happen—a suture that’s slightly loose, an unnoticed small opening in a blood vessel—things we’re not aware of that don’t come to fruition in the patient’s postoperative course as some patients are able to heal better than others and overcome these small incidences. Complications are often a result of a number of minor errors rather than just one small error that can go unnoticed. But with this process, you’re able to see the most minute things and get feedback and information you would never get from a normal case.”

These models have enabled Ghazi and other surgeons to gain vast amounts of experience that outpaces the number of cases. “It’s opened us up to ask, why don’t we do this for other procedures? How do we make it more common, more relevant to a significant number of procedures?” says Ghazi.

For example, procedures like stone removal involve variables that surgeons can’t measure ahead of time, like temperature and pressure. Lasering a stone creates a significant amount of energy. Urologists aim to predict how much of the stone will be left behind, how it will flush out, and how much temperature can be generated without damaging tissue.

“There are red lines drawn in the sand that we don’t want to pass, and we underplay because we don’t want to get close to the red line,” explains Ghazi. But the models enable trials of these procedures to gauge results and better predict outcomes for live patients. “What we’re trying to do is almost create a formula: If this is the stone, this is the size, this is the type of kidney, we’ll be able to say these are the ideal settings that would be relevant to a significant number of patients.”

Practice, not training

Ghazi says part of the mission of this new technology is to encourage qualified surgeons to get into the habit of practicing their surgeries beforehand. Practice, he says, is a lifelong process. “As we move forward in the field, there’s more and more technology that separates us from the patients,” says Ghazi.

The technology has been strongly endorsed across many surgical societies, with the American Urological Association using it in training courses. Perhaps even more exciting, Ghazi says, is that experienced surgeons have gravitated toward it.

“If you find an experienced surgeon truly immersed in procedure while performing the model and stay with it until the end, that means they truly feel they are actually doing the real procedure,” he says. “When a practicing surgeon is locked in like that, you’re onto something, because it’s similar to what they do in real life.”

Surgeons need to log many hours before they become proficient with advanced surgical tools that let them tackle complex urological procedures. For junior trainees, the model technology breaks a barrier to learning. Ethical and legal directives mean supervised training on patients is becoming less acceptable. “Cadavers and animals are difficult to obtain, and virtual reality isn’t there yet,” says Ghazi. “There’s still a disconnect between the real thing and the virtual world, and the technology still has a significant need to improve.”

But with a hybrid model using realistic physical molds, trainees are able to practice all the steps of live surgery without the potential of harm. They get immediate feedback, and it becomes clearer when they are ready to proceed to independent practice, Ghazi adds. “We’re able to install sensors in the model that feel torque, touch, temperature,” he says. “And now you have a training where you can let the trainee veer into the wrong lane and let them do it so that they realize they’ve done something wrong.”

Deliberately allowing a trainee to make an error isn’t an option with a live patient. But with these physical models, trainees have the leeway to learn from their mistakes, developing a sense of not only what went wrong but how to correct it so the mistake doesn’t recur. “The way we do surgery has changed with technology being an integral part of surgical procedures, to the degree that this technology is now an intermediary between us and the patient,” says Ghazi. “Visual cues are our main input.”

There’s almost an aura of science fiction to this technology. “I never thought, when we started this 10 years ago, we’d get this far,” says Ghazi. “When we started doing it we had very high standards for our criteria, that these models have to at minimum look, feel, and react the same as real patients.”

There is still a barrier to entry. The work is done by a unique lab with specialized techniques, and the team is still looking for ways to make the process more accessible to more surgeons. It can be time consuming, and there will always be a financial hurdle to circumvent. Ghazi and his team have even approached malpractice insurance companies to discuss whether the improved outcomes would justify some kind of financial incentives to conduct these rehearsals.

“Our hope is that if we generate enough momentum and evidence that this is really beneficial, that very soon it will become available,” says Ghazi. “We need new ways to train people. If you have the resources, the technology is there.”

Matt Phillion is a freelance writer covering healthcare, cybersecurity, and more. He can be reached at matthew.phillion@gmail.com