Sandia bonelike microscaffolding may benefit patients
In an operating room in Carle Hospital in Urbana, Ill., on May 7, with scientists from the University of Illinois and Sandia looking on, Dr. Michael Goldwasser, an oral and maxillofacial surgeon, fitted a highly unusual prosthetic device into the mouth of an elderly woman who had lost most of her teeth and along with it, much of the bone of her lower jaw.
The purpose of the fitting was to see whether the implant had been accurately designed, from its overall shape down to inclusion of a nerve groove.
"If it had fit like a sock on a rooster, our method wouldn’t have worked," Goldwasser said.
Observers said it fit like a glove.
If approved by the FDA for testing, the scaffoldlike structure — a layered mesh stronger than bone, yet porous — would substitute for a portion of the mandible, or lower jaw, until healthy, newly grown bone and blood vessels could weave their way through it.
The ceramic scaffolding would reduce the pain, recovery time, and chances of infection of those needing bone replacements in the jaw, as well as skull, spine, or other bony areas. It is built mainly of hydroxyapatite, a material already approved by FDA for bodily implants, so approval of the new device could be swift.
Sandia has applied for a patent.
The woman was reportedly pleased to be part of an experiment that might benefit humanity, because the quality of fit would determine whether scientists and doctors using computer programs, modern communications, and machines a thousand miles from each other could produce a prosthetic device that would fit seamlessly in a patient’s sensitive mouth — or, for that matter, skull or spinal vertebrae — without the manufacturers ever seeing the patient.
But because the device’s strength and permeability have been studied only in vitro (in the lab), the woman had then to endure the standard method of bone replacement, which by comparison seems almost medieval. This involves cutting a several-square-inch piece of bone from her pelvis, which is then power-sawn and drilled into the correct shape right in the operating room, a process that takes about an hour and leaves the patient with the job of healing pelvis as well as mouth.
"Surgeons and patients would love to eliminate both the retrieval and implant preparation processes," says Sandia scientist Joe Cesarano (1843), whose team fashioned the new implant. "This test showed we can make artificial porous implants prior to surgery that will fit perfectly into the damaged region. the reconstructive procedure would then only require attaching the implant and closing the wound."
A short course on bone implants
Ideally, says Goldwasser, a surgeon would use the patient’s own bone to minimize rejection by the body after trauma or tumor removal has left an absence of bony architecture in face or skull. Harvesting bone, however, creates new problems. Not only is a new area of patient discomfort opened but the time of operation and amount of anesthetics are increased. These raise the risks of complications in the operation and in healing. "We could use cadaver bones," he says, "but then we face risks of rejection by the host and of possible transfer of disease."
The body may also dispose of the foreign bone prematurely by absorbing it.
"What we want," Goldwasser says, "is a method by which I can see a patient in Illinois, transmit X-ray information to someone who can make a substitute part that would have the porous properties that would allow bone to grow into it, yet be strong enough for normal function. Here, this would mean mastication and appearance."
With the aid of UI bioengineering professor Russ Jamison and graduate and Sandia summer student Jennifer Dellinger, who were experimenting with the growth of bone across porous surfaces and needed a more regularly porous substrate than those found in nature, he learned of a device at Sandia that could do the job.