Roanoke Times
Copyright (c) 1995, Landmark Communications, Inc.
DATE: WEDNESDAY, February 12, 1992 TAG: 9202120261
SECTION: NATIONAL/INTERNATIONAL PAGE: A4 EDITION: METRO
SOURCE: The Baltimore Sun
DATELINE: BALTIMORE LENGTH: Medium
NEW ARTIFICIAL DISC MAY RELIEVE THAT ACHING BACK
If you are older than 20, your spine has already started to wear out.Cheer up, however, for the new director of spinal surgery at Johns Hopkins Hospital is racing to have replacement parts in stock before it finally does.
Sometime this year, Dr. John P. Kostuik and his biomechanics team hope to start human trials on an artificial disc made of titanium and cobalt chrome that may one day provide relief to the 50,000 patients who develop painful spinal disc problems every year.
Disc ailments are among the many causes of lower back pain, which is at "epidemic" levels, Kostuik says. And as the U.S. population ages, it will become more so.
The silvery new disc has a pair of coiled springs that will absorb skeletal shocks with a life-like "bounce." It's designed to last 40 years, or 100 million steps, whichever comes first.
If the artificial disc works, it will spare patients much of the pain and risk of spinal fusion surgery, which now ends in failure 15 percent of the time, Kostuik says. The artificial-disc implant would ease one of the most common lower-back injuries, the ruptured or herniated disc.
The natural discs are tough, jelly-filled capsules between individual vertebrae in the spinal column. Their role is to separate the bony vertebrae, cushion the repeated shocks of walking and running, and provide flexibility.
Unfortunately, "discs start to wear out in everybody at about 20 years of age," Kostuik says.
When discs tear or leak, the injury can cause acute pain at the disc itself, or put painful pressure on adjoining nerves. The pain can range from mild and intermittent to severe and chronic.
In spinal-fusion surgery, doctors remove the damaged disc, "rough up" the facing surfaces of the adjoining vertebrae and fill the joint with grafts of bone taken from the pelvis. Then the spine is immobilized with screws and plates until the spinal bones simply grow together into a single unit.
When it works, the procedure eases pain. But it also reduces the flexibility of the patient's back, and demands six months for healing and three months of rehabilitation.
In 1987 nearly 59,000 spinal fusions were performed in the United States at a cost of about $40,000 each, or $2.36 billion. An estimated 15 percent of the surgeries failed, Kostuik says, adding $356 million to the costs. By the year 2000, Americans will spend $5.2 billion for 65,000 fusions, and $784 million more to repair the failed ones.
Implantation of a durable artificial disc, he said, would require no bone graft from the pelvis, often the greatest source of pain after fusion surgery. Recuperation would shrink to six weeks, and earlier rehabilitation would speed the patient's return to work.
Kostuik is focusing on the lower back because it is the site of most painful back injuries.