March 26 (HealthDay News) -- Chinese surgeons are reporting long-term success with the first use of transplanted spinal discs to relieve back pain.

Spinal discs from human donors were transplanted five years ago into five patients with chronic back pain caused by disc degeneration, physicians at the University of Hong Kong and the Naval General Hospital in Bejing said.

As reported in the March 24 issue of The Lancet, the five-year follow-up found an improvement in symptoms, no signs of immune rejection and only mild degeneration of the transplanted discs.

"Very creative," was how Dr. Barth Green, chairman of neurological surgery at the University of Miami Miller School of Medicine, described the breakthrough technique. "But I think five patients are way too few to see whether this is going to be the answer for the long run," he added.

Spinal disc transplants could have a real future, however, because surgeons are not always happy with the results of current operations, Green said. When back pain cannot be treated with medications, a surgical procedure called fusion is done, uniting the bones to relieve the pain. Recently, surgeons have started to implant artificial discs in some cases.

"This is going in the right direction," Dr. Roger Hartl, director of the spine program at New York Presbyterian/Weil Cornell Medical Center, in New York City, said of the Chinese work. "Biological replacement of a disc rather than fusion surgery or artificial discs are the way to go. To me, the results are very promising. People have done this in animals, but the nice thing abut this study is that it is the first time it has been done in humans."

Hartl is working with biomedical engineers at Cornell University's main campus in Ithaca, N.Y., trying to grow replacement discs using cell cultures.

Like Green, he remains cautious about the Chinese report, however. "The five-year results look good, but the numbers are too small to draw conclusions about the possible accelerated degeneration of other discs near the surgical site," he said.

Another reason for being careful is that "there is not much information about where the patients came from, why they had surgery and where the transplanted specimens came from," Hartl said.

In addition, "it is hard to imagine now that this will become standard treatment for people who have degenerative disc disease because of the problem of donation," Hartl said.

Green disagreed on that point. "Every hospital in the United States uses cadaver bones for spinal surgery," he said. "So the real question is what the results are."

It's too early to tell, Green said. "I don't think we're anywhere near ready to start doing it routinely because of the fact that a lot of important details have to be worked out."

The Chinese researchers pointed out some of those details, noting that "improvements in the area of graft preservation, repopulation of the allograft [transplant] with living cells and surgical techniques" are needed before disc transplants could be recommended for standard use.