Bone Transplantation Without Rejection

How a 3-D-printed titanium jawbone was transplanted into an 83-year-old patient

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Steven Cherry: Hi, this is Steven Cherry for IEEE Spectrum’s “Techwise Conversations.”

Ever since the world’s first bioengineer, Daedalus, made wings for himself and his son Icarus, we’ve tried to add body parts to people the way a blacksmith adds shoes to a horse. Sometimes it doesn’t work out—Icarus's wings melted when he flew too close to the sun.

But sometimes it does.

Last June, an 83-year-old Belgian woman suffering from oral cancer and an infection that was eating away at her jaw received a jawbone transplant that took a team of 10 surgeons 11 hours to complete. The BBC reported on the story on Monday.

The operation was a success. Reportedly, the patient was able to eat and speak with the new jaw within hours. The operation was an even more remarkable success in one other respect: The jaw itself was manufactured with a 3-D printer.

It was built of titanium powder by a surgical team from Belgium’s Hasselt University and engineers from LayerWise, a Belgian provider of engineering and production services for industrial, dental, and medical applications.

My guest today is Peter Mercelis. He has a Ph.D. in electromechanical engineering from the University of Leuven in Belgium. In 2008 he founded LayerWise. He joins us today by phone from Leuven.

Peter, welcome to the podcast.

Peter Mercelis: Hello. Thanks for calling.

Steven Cherry: Let’s start with the patient. How is she doing now?

Peter Mercelis: In fact, she’s doing very well. The procedure itself was performed in June. Yesterday the dental treatment started, so the titanium jaw that was implanted in June is now perfectly healed. That means that the muscle tissues are attaching very well to the implant. The patient also has chewing function back. Of course, she’s still a bit weak because she does not have the capacity yet to eat normal foods. So the dental treatment—that means the dental prosthesis that will be manufactured and installed normally within two months time, just because all the soft tissues also need to time to heal properly. But apart from that, she’s doing very well.

Steven Cherry: That’s really wonderful. Jaw transplantation is a really new thing. The very first one, as far as I can tell, was done in 2003 using a donor jaw, and then since about 2006 they’ve been using the patient’s own bone marrow to reduce rejection problems. I gather there really weren’t any rejection problems here because of the titanium.

Peter Mercelis: Yes, that’s true. Titanium is a very well known material in the medical implant industry, so it’s a material that’s very well known for its biocompatibility. Metal implants have a bad reputation lately in orthopedics, but that’s a totally different category of material. So these are the cobalt-chromium alloys that we are speaking of. Titanium, on the other hand, is a very well accepted material, so very few allergic reactions are reported due to titanium.

Steven Cherry: Right, and I guess it’s used pretty frequently in regular dental implants.

Peter Mercelis: I would say that the majority of medical implants today is manufactured from titanium, going from hip joints to dental implants; also, all kinds of screws and plates that are used in trauma fixation, to repair complex fractures—most of them are made from titanium, with very good results.

Steven Cherry: So, let’s go step by step in the process of creating this jawbone. First of all, how did LayerWise come to end up doing this work?

Peter Mercelis: We are known especially in Europe as one of the only companies offering this technology already on a larger scale. So a lot of people are working on this technology on a lab scale, I would say, in research institutes. We are one of the few companies offering this technology for customers worldwide in not only the medical industry but also in dentistry and industrial applications. Now, the surgeon that initiated this case, Professor Jules Poukens, is also one of the pioneers in, I would say, additive manufacturing technologies, so he has been working with rapid prototyping technologies for about a decade, I think. And he’s been using medical models printed by 3-D printing to prepare his surgeries and so on, so he was well aware of our company, and we had been working together on research projects in the past. So that now the collaboration between the surgeon, the medical designer, and ourselves came very naturally, in fact.

Steven Cherry: So tell us about the 3-D printing part. You start with this titanium powder, and it gets created in three dimensions, in layers?

Peter Mercelis: Yeah, that’s correct. So it all starts from a three-dimensional CAD model of the implant. So the patient is first, of course, scanned using CT scanning; this scanning data is then converted back into a three-dimensional model, so we have a virtual model of the infected jaw of the patient. Then a medical design company from the Netherlands, a company [called] Xilloc Medical, started on the design of the implant based on this patient data. The three-dimensional design of the implant was then sent to us as a manufacturing company, and internally with LayerWise it all starts with this three-dimensional model. Then we use our software algorithms to calculate a very large set of two-dimensional sections of this implant. So we actually slice this implant into two or three thousand very thin layers, and we then send this information to our machine. And on our machine we built this three-dimensional component layer by layer by melting titanium powder with a laser beam. So the implant itself consists of, I would say, 3000 very thin layers of material that are molten together. So in fact we use a very fine titanium powder, we spread it with a kind of coater, then we use a focused laser beam that we can control very well, and we use this laser beam to scan the two-dimensional sections of the implant. What happens then is that due to the heat of the laser this titanium powder melts, and when it solidifies again you have created one two-dimensional section of your three-dimensional object. So if we then apply a next powder layer on top, we can continue this process all over again. So it’s in fact not such a fast building process if you look at the productivity of the process, but it’s very fast since you can start directly from a CAD model. You do not need any special kind of tools or any special mold to create the object, but you just start from the 3-D model and print it from the powder.

Steven Cherry: Now, I gather it’s a pretty complex object that you’re creating. It’s got cavities for muscles to attach to, and grooves for nerves and veins to generate through it.

Peter Mercelis: That’s true, yeah. So the design was not exactly as a normal human jawbone, of course, because the muscles that are normally attached to the jawbone, they had to be cut off from the normal jaw. And in order to attach them successfully to the titanium implant, a lot of cavities were created and openings that could be used for the suture wires, for example. And that seems to have worked very well, because surgeons—yesterday they saw the patient again, and it seems that the muscles are very well attached to the implant, and that could already be observed the next day after the surgery. So the next day the patient could already move the jaw very well. So that was a real success.

Steven Cherry: That’s tremendous. The operation itself—were you or somebody else from LayerWise in attendance?

Peter Mercelis: I witnessed the operation in person and also did Mr. Michael Beerens from the medical design company, so that gives us new ideas for future applications, of course. And it’s very important in these kinds of complex cases to have a very close and good collaboration between the surgical team and the engineering team.

Steven Cherry: I can imagine. Now, you’re degree is in electromechanical engineering. Do you have any medical background at all?

Peter Mercelis: Just by experience, I would say. So my background is indeed mechanical engineering, but I did my Ph.D. on this topic of selective laser melting technology, and since we founded LayerWise in 2008, I have been focusing on medical and dental applications of this technology.

Steven Cherry: One of the doctors involved in the operation was quoted as saying, “Computer technology will cause a veritable revolution in the medical world. We just need to learn to work with it.” Do you think we’re going to see a medical revolution here?

Peter Mercelis: I think it has already started, because this is now the first time that a full bone structure, a full jawbone, is being replaced by an implant. But it’s of course not the first case of applying custom implants or digital-designed implants, and I think that will gradually evolve. I think there’s quite a good consensus that an implant should fit the exact anatomy of the patient in the best possible way. So of course you end up making custom implants in that case. One drawback of this technology is of course the cost that is associated with it, so if you can produce implants by using mass-production technologies, they will of course be cheaper. But what we try to do and is very important is to look at the total cost for the patient or for society. So you should not look just at the cost of the implant—that is most likely more expensive than a standard implant—but if you take into account the drastic reduction of the operation time, the number of hours of operation in the theater, and you take into account the faster recovery of the patient. So in this case, the patient left the hospital after three days, whereas normally such an operation requires a hospitalization of about three weeks. If you take into account all these different aspects, then the total cost will most likely be lower than when using a standard implant. So we do not claim that standard implants should not be used, of course not—but there’s a category of patients that can benefit from a custom solution.

Steven Cherry: Now, back in November there was a report of creating ceramic structures that bone could grow around, and I see also that 3-D printing has been used to create blood vessels.

Peter Mercelis: Yeah, yeah, yeah. So the 3-D printing technology is not limited to the use of metals. So it can be used—and has been used—for a decade or two decades for plastic prototyping, but it’s now being developed more and more for other materials. So we are pioneers in the applications in metal components, but the technology is now being developed more and more for ceramic materials, for biodegradable polymers for example, and also for living cells, living tissue. So—yeah, there’s not really a limitation on the kind of material that you can use.

Steven Cherry: Very good. Well ,you know, Peter, surgeons get to see every day the good they do in the world; that’s a pleasure that’s usually denied to engineers. It must feel very good to have contributed to some other person’s well-being like this.

Peter Mercelis: Yes, that’s definitely true. So we were very glad that we could help this lady in this case by making her new jaw, and I hope we can do it again in the future for other patients.

Steven Cherry: Very good. Well, thank you so much for joining us today.

Peter Mercelis: You’re welcome, and thank you very much for calling.

Steven Cherry: We’ve been speaking with Peter Mercelis, founder and managing director of LayerWise, a Belgian company that created the world’s first 3-D jawbone for medical transplantation. For IEEE Spectrum’s “Techwise Conversations,” I’m Steven Cherry.

Announcer: “Techwise Conversations” is sponsored by National Instruments.

This interview was recorded 9 February 2012.
Segment producer: Barbara Finkelstein; audio engineer: Francesco Ferorelli

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