"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.
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."
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."