A Chip off the Old Cadaver

Using specially treated bones, doctors make repairs in humans

A child is born with a putty face: gaping hole for a mouth, eyes spaced widely apart, the facial bones not yet developed. Another, born without any bone in his nose, has nostrils projecting forward so grotesquely that his face resembles that of a pig. A third youngster loses his jawbone in an accident, and, as a result, his teeth are about to fall out.

For children with such horrific structural defects, the only solution is extensive and grueling surgery. Doctors take bone from the patient's own body, usually from the ribs or hips, and graft it to the existing bone in the head and face. Unfortunately, the patient has a limited amount of spare bone, the "harvesting" process can mean additional trauma, and frequently the transplanted material is absorbed back into the body before new bone has formed. But now doctors may have a way of overcoming these difficulties. Last week Boston researchers announced that they had made successful repairs in more than 40 patients by using specially treated bone from cadavers.

In the technique, developed by a team headed by Surgeon Judah Folkman of Children's Hospital Medical Center and described in the Lancet, the bone is made into strips, blocks, chips or powder and soaked in hydrochloric acid to remove all minerals. It is then dried, sterilized and stored. When needed, it is mixed with a saline solution. Says Plastic Surgeon John B. Mulliken, also of Children's Hospital: "The powder, which then has a pasty consistency, is used to caulk around defects, to fill in holes, irregularities, and is shoved into places hard to get at. The chips, though rubbery, immediately give some stability and form." Cartilage and then bone appear, usually within six months of the implant.

In conventional transplants, the grafted material serves as scaffolding for bone cells migrating from adjacent tissue. But, the researchers say, something else apparently happens with demineralized bone: it induces the host tissue to form completely new bone. "This material changes the cells it comes in contact with," Biochemist Julie Glowacki explains. Fibroblasts, the cells that produce the connective tissue in the body, become osteoblasts, which are bone-producing cells. Though no one knows why the conversion occurs, scientists speculate that the demineralized material delivers an electrical signal to surrounding cells.

The Boston researchers tested the technique in 4,000 rats before turning to human subjects 2% years ago. The results have been extremely encouraging, particularly in correcting youngsters' congenital deformities. The putty face now has normal shape, and the piglike face has a nose.

The jawless child grew a new one after only a brief operation to insert demineralized bone.

The most extensive use of demineralized bone taken from humans (and possibly some day from animals) may be to treat accident victims or people who are losing jawbone because of periodontal disease or tooth loss. But the researchers caution that the procedure is still experimental and must undergo more clinical tests before it comes into widespread use. Says Mulliken: "We just don't know how strong the bone is going to be." Adds Oral Surgeon Leonard Kaban: "We are trying to go very slowly with this. We don't want it to be a case of the emperor's new clothes, where everybody wants it to work so much that they just believe it does."

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