Experimental Surgery May Be a Solution for Spinal Stenosis

Jan. 21, 2008 — -- When 67-year-old Dean Malliaros was facing spine surgery in September, he took a chance few others have.

He volunteered for a procedure his doctor had never performed, using a joint replacement that still needs five more years of study before it is approved by the U.S. Food and Drug Administration.

At stake was Malliaros' ability to continue his normal daily activities, and possibly even his ability to walk. He suffers from spinal stenosis, a condition where the bones or ligaments in the spinal canal begin to thicken and narrow, slowly squeezing and clamping down on the spinal cord over time.

Current treatments for the condition are not perfect, and the new procedure is not without its risks. Any time doctors implant an artificial joint, there is a concern that natural wear and tear will grind off microscopic particles of the metal joint — a "dust" of sorts. If this dust is somehow harmful to surrounding tissues, doctors — and the patient — can have a big problem on their hands.

And then there is the worry of how long the joint will last, especially since the quicker it wears out, the sooner the patients will have to return for major — as possibly risky — surgery.

But the success of this implant could have big implications for others who suffer from spinal stenosis. As many as 500,000 people in the United States — most of them older than 50 — suffer from noticeable symptoms, according to the University of Washington Orthopedics and Sports Medicine Department.

People with spinal stenosis can lose control over their bladders and experience erectile dysfunction. Sufferers may also find that their feet go numb, their legs hurt, and they begin to hunch over — a motion that allows slightly more wiggle room for their nerves in their spine.

"You can go to the grocery store on a Tuesday afternoon, and see people with spinal stenosis leaning on their grocery cart trying to make it around," said Daryll Dikes, an orthopedic spine surgeon in Minneapolis, Minn.

Despite the pain associated with this condition, medical advancements to treat joint pain in the spine have lagged behind joints in other parts of the body. Replacement ball-and-socket joints like the hip and simple-hinge joints like the knee have been around for decades. But the facet joints in the spine are more difficult for medical engineers to replicate.

For nine years, Malliaros tried the usual treatments for spinal stenosis: epidural injections and heavy-duty nerve blocks for the pain. But the condition got worse, and Malliaros, who used to regularly swim and run, could only walk with a cane and for short distances. At that point his doctor called him in for a surgery consultation.

Sitting in the waiting room, Malliaros began to feel less optimistic about his options.

A New Last Resort?

"They all were complaining that they wished they had never had a [spinal] fusion operation done because of the rigidity," said Malliaros. "You always have problems above and below the fusion."

Spinal fusion surgery is currently the last resort for people with spinal stenosis. Sometimes doctors can remove the tiny bone spurs that leave nerves red and inflamed, but often so much of the facet joint has degenerated that fusing two vertebrae into one gives the best pain relief.

Spinal fusion makes space for the nerves, but it puts the vertebrae on either side of the fusion in under extra stress.

"Think of a six-car train progressing around a curve on the track," said Chris Bono, Malliaros' doctor and a spine surgeon at Brigham and Women's Hospital in Boston.

With fusion, "you take two of those cars and you lock them," said Bono. The train, says Bono, will still go around a bend, but since two cars are locked, the joints on either side will have to bend more to keep the train on the track. A similar situation occurs in the back, with vertebral joints on either side of the fused bones experiencing the bulk of the additional stress.

But Bono could offer Malliaros' another choice besides fusion, since he is participating in a clinical trial with Archus Orthopedics, one of three facet joint replacement manufacturers seeking FDA approval.

"I'm not going anywhere, that's what I want," Malliaros recalled saying when he heard about the trial.

Malliaros has gone through 11 orthopedic surgeries in the last six years for his hips, knees and shoulder. He knew enough to figure that having his facet joints would make a big difference in his ability to get around.

An Elegant Movement

Facet joints are some of the more sophisticated in the body. They stabilize the back and allow the extraordinary movement of the spine, which can bend back and forward, side to side, extend and twist, says Dikes. That's much more complicated than the single motion of a knee.

In addition to developing a prosthetic facet joint that could move naturally, companies needed to develop metal alloys that would be flexible and strong, and that would not break down into dangerous metals in the body.

The first facet joint replacement took place only a few years ago in Romania, says Bono, who describes the procedure as a tinker toy assembly with 13 small pieces, some the size of a bean.

"It's a skill we don't learn in medical school, or even medical residency," said Bono. "It's a skill to be comfortable with your hands enough to get the little parts aligned the right way."

The Result

Four and a half hours of surgery later, Malliaros was done. The surgery left him with a five-inch incision and a new piece in his spine.

And even Bono was surprised by how well Malliaros recovered.

"The results have been phenomenal," said Malliaros. Two days after the operation, Malliaros recovered from the pain from surgery. Four days later, the pain in his legs went away.

Neither Bono nor the medical community has a way of knowing how long Malliaros joints will last. As with knee replacements, the joints may need to be replaced in 10 or 15 years. But for now, Malliaros is happy.

"I was always fearful of falling before," said Malliaros, but no longer. "I threw my cane away."