Teri Klein’s sciatica from a herniated disc was so bad she could no longer work as a dental assistant. Prolonged sitting and bending and twisting were too painful for the 44-year-old mother of three from Sublette, Ill.
She was a prime candidate for spinal fusion surgery, which removes the diseased disc and fuses the surrounding bones together. Then she heard about a clinical trial at Northwestern Memorial Hospital that compares a new artificial back disc with spinal fusion to treat degenerative disc disease in the lower back.
Discs are gellike cushions between each bone of the spine. As people age, their discs lose their flexibility, elasticity and shock-absorbing ability. When this happens, some people experience symptoms such as back pain, leg pain, numbness and tingling.
The Maverick disc, manufactured by Medtronic Sofamor Danek, is made from a cobalt-chrome alloy. Other artificial discs are made from plastics or polymers, which can wear out over time. The Maverick’s two parts fit together in a ball and socket and can move side to side or back to front, giving the patient increased range of motion, said Dr. Srdjan Mirkovic, a spine surgeon at Northwestern Memorial Hospital and the study’s principal investigator.
Northwestern is one of 30 sites nationwide testing the artificial disc. Study candidates are people in their 30s or 40s who have failed conservative treatment such as medication, local injections and physical therapy for at least six months and whose pain stems from the two lower back discs.
About two-thirds of study participants will receive the artificial disc and the rest will receive spinal fusion. The goal of surgery is to control pain, Mirkovic said.
With fusion, surgeons have to immobilize the lower back with a brace and wait for the bones to fully fuse, which can take six months to a year, said Mirkovic. The patient loses some flexibility in the spine.
If the patient’s pain persists or recurs after the artificial disc is inserted, doctors can remove it and do spinal fusion, but not vice versa, Mirkovic said. Risks of the artificial disc are the same as with fusion: infection; significant bleeding; sexual dysfunction in men; and injury to blood vessels, nerves, the bowel and ureter. Also, the disc might shift position or become misaligned over time.
Artificial joints in knees and hips have been around for decades, but replacing a disc near the spinal cord is trickier. “We can now insert an artificial disc in this critical location because of improvements in surgery and better knowledge of the biomechanics of the lumbar [lower] spine,” said Mirkovic.
The greatest advantage of the Maverick disc is that people don’t need to wear a brace, Mirkovic said. They are walking the day after surgery and require less pain medication than with fusion. Some return to work a month or two after surgery.
Klein received the artificial disc in November. Surgeons entered her abdomen through a small incision, removed the diseased disc and inserted the artificial disc in its place. A calcium-rich substance anchors it.
When she went home two days later, she took only an over-the-counter pain reliever. She returned to the hospital for a checkup two weeks later and made the two-hour, 20-minute drive home herself, she said.
“I have no pain anymore, no drop foot or sciatica,” she said. “With chronic pain, you can’t go through daily life. It rules you. Taking medicine is no way to live, either.”
Kurt Bodell’s recovery after receiving the artificial disc in November has been slow but steady. The 43-year-old father of two from La Grange stands on his feet all day as a trader at the Chicago Board of Trade. For the last decade, he has had muscle aches and spasms in his lower back. He enrolled in the study because “I was tired of being miserable.”
Bodell spent four days in the hospital and missed just three weeks of work.
“After a month I started to feel better, and the stiffness went away,” he said. “Right now I’m 70 percent and getting even better. I’m able to live my life without as much pain. If I drop a penny, I can pick it up or tie my shoe like a normal person.”
If the Maverick gets high marks, spinal fusion won’t go by the wayside, said Dr. John Liu, a neurosurgeon at Northwestern Memorial and co-investigator of the study.
“It’s important to evaluate patients properly to see if they are a candidate for this disc,” he said. “There are many treatments, and you need to offer patients the right operation. For certain patients, spinal fusion can work very well.”
Artificial discs must prove themselves over the long term, said Girard Senn, a health consultant in Oak Brook. “There is no definitive evidence in the literature today that indicates a long-term difference in outcome between fusion and implants.”
The National Institutes of Health is conducting a study of long-term outcomes of fusion versus implants.
There is a significant cost difference between the two procedures, Senn said; surgeons and hospitals are paid up to four times more to do a disc implant than a fusion.
“I am pleased to see the federal government studying these procedures,” Senn said. “If the NIH studies don’t show long-term improved outcomes for artificial discs, I trust the Centers for Medicare & Medicaid Services would adjust the physician and hospital incentives so as to encourage the correct procedure for the patient. I want to see long-term quality improvements for patients without device failures, say, over five years, and not just short-term improvement, such as in increased flexibility.”
Those interested in the artificial disc clinical trial can call 866-548-7425.
And in their neck of the woods . . .
An artificial cervical disc for the neck also is being studied as an alternative to spinal fusion surgery.
Loyola University Health System in Maywood is one of 20 centers nationwide evaluating an artificial cervical disc created to alleviate neck pain associated with disc herniations, spinal arthritis and other degenerative spine conditions.
The disc consists of two stainless-steel components that are attached to the vertebrae with screws. The components are designed to act as a pivot point, which may allow the spine to move more naturally.
“This new device may provide patients with an alternative to spinal fusion that may allow them to be more active following surgery and may reduce the long-term complications of spinal fusion,” said Dr. Russ P. Nockels, a neurosurgeon at Loyola University Medical Center. “The only approved method today to help patients is to clear away the troublesome bone spurs and disc material and fuse the cervical vertebrae together.”
Interested study candidates may call 708-216-0005.
–T.Y.S.
