Originally Published EMDM
October 2004
A NOTE FROM THE EDITOR
From Bad to Wurst
For a German carnivore—and I realize that phrase is somewhat redundant—it was a fate worse than death. A 56-year-old man has spent almost 10 years eating only soft food and soup after his lower jaw was removed because of mouth cancer. No Nürnberger Bratwurst, no cordon bleu, no Schweinshaxe. According to reconstructive facial surgeon Patrick Warnke at the University of Kiel, “He was really sick of living.” But this story has a happy ending for the patient, and for medical technology.
The 28 August issue of the medical journal the Lancet published an article describing a revolutionary procedure that grew a jaw, from scratch, under this man’s shoulder blade and transplanted it to his mandible. Warnke and a team of scientists used a CAD system to design a virtual replacement for the missing portion of the jaw. The CAD data were transferred to a milling machine to produce a Teflon mould. A titanium mesh scaffold was then constructed around the mould. The mould was removed, and the resulting titanium cage was seeded with bone mineral blocks, genetically engineered human bone protein, and bone marrow. It was implanted into the patient’s latissimus dorsi muscle, and 7 weeks later was transplanted as a free bone-muscle flap to repair the mandibular defect, write the authors in the journal. They report that the patient is delighted with his renewed ability to chew and satisfied with the aesthetic outcome.
If this procedure has long-term viability, it will offer a much-needed alternative to the use of allogenic organ transplants, which are subject to the harsh law of supply and demand. Harvesting autologous bone grafts also poses problems. Warnke notes in the Lancet article that conventional techniques to replace the jaw would have required transplantation of a microvascularized fibula bone. “This would have created a major bone and soft tissue defect of the lower leg,” he writes. “The morbidity associated with this would have been great.”
If the tissue-engineered jaw does stand the test of time, Dr.-Ing. Michael Wehmöller can take some of the credit. An engineer at Cranio Construct Bochum (Bochum, Germany), Wehmöller oversaw the design and manufacture of the titanium implant. He has been active in this field since attending Ruhr University–Bochum, where he earned his doctorate.
“We began doing research on this at the university in 1994,” says Wehmöller. A challenge in the early days was finding a reliable way to transfer the computed tomography data to a CAD/CAM system. Once the CAD/CAM interface had been optimized, Cranio Construct Bochum was spun off as a company. Fast-forward to 2004, and designing a jawbone for Dr. Warnke’s patient was all in a day’s work, Wehmöller says laconically.
“There was no particular difficulty from a geometrical standpoint. We have been doing this for several years now, and our implants are used throughout Europe, in the United States, and soon, we hope, they will be used in China,” says Wehmöller. The company has more than 100 reconstructed jawbones currently referenced in its database. This allows the firm to build on existing designs, rather than start from scratch, and concentrate on refining the implant’s functionality.
The firestorm of media attention is a mixed blessing for Wehmöller. He is appreciative of the publicity for his company, but he readily admits, “We researchers don’t know how to manage all this PR.” Specifically, he is wary of the media’s penchant for narrative shortcuts. “We have to wait and see what happens to the patient and, perhaps, make some modifications along the way,” says Wehmöller.
Looking ahead, continued mineralization of the induced bone may allow removal of the external titanium mesh scaffold. Warnke thinks this may be possible one year after transplantation. Once this has been done, the repaired mandible will be subject to normal functional loading, writes Warnke, and can undergo remodeling.
In the meantime, the anonymous patient has found a new lease on life. And guess how he celebrated his new tissue-engineered jaw? By biting down on a Bratwurst, natürlich.
Norbert Sparrow
Copyright ©2004 European Medical Device Manufacturer
