Oct. 30, 2003

Contact: Roger Martin, KU Center for Research, (785) 864-7239.

KU researchers engineer synthetic spinal tissue to aid surgery to repair discs

LAWRENCE -- A spine is a simple thing, a column of bones with gristly discs sandwiched between them. It's a simple thing, that is, until it fails and surgery is needed.

At that point, surgeons need a good replica of a spine that lets them test in advance how a surgery on one part of a patient's backbone will change loads and pressures elsewhere. Two University of Kansas scientists are working to perfect synthetic soft material for use in constructing the discs and ligaments of an artificial spine.

The materials are made of silicone embedded with wire and fabric meshes.

The KU scientists are partnering with a Seattle company, Pacific Research Laboratories, that makes synthetic bones.

"What we're doing is putting together our soft tissue with their bones to form a mechanical version of a lumbar spine segment," said Elizabeth Friis, KU assistant professor of mechanical engineering.

Friis is applying to the National Institutes of Health and private foundations for funding. With funding, she said, the artificial spine could be ready in two years or less.

Currently, doctors use the spines of dead calf and sheep, which are commercially available, to simulate the movement of parts of a human spine.

"But the natural materials change their physical properties in a very short time, and the spines of the animals aren't like a human spine," said Doug Pence, clinical associate professor of surgery at the KU School of Medicine in Wichita.

Surgeons often address spinal problems by removing some disc material from between vertebrae, then fusing the discs.

It's medically complicated. Small shards of living bone, buttressed by cages, screws, rods and other metal inserts, must grow together for the vertebrae to fuse.

The surgery also is complicated in an engineering sense, raising problems much like those faced when engineers design bridges or skyscrapers.

For example, fusing two vertebrae that have been mobile shifts the distribution of pressures and loads on the backbone above the point of fusion.

Computer models of the spine have limitations, said Friis, so "we're building a model that reproduces the motions -- and rigidities -- of the human spine."

The artificial spine will be useful in the future when spinal surgeons do disc implants. Such surgery is in clinical trials in the United States, the researchers said.

"A lot of types of implants are being designed but not tested sufficiently," Friis said. "Our model reproduces the motion of the human spine and will let you test the consequences of implants before they're put into patients.

"We've received a lot of attention from implant manufacturers."