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Total Disc Replacement Replaces Spinal Fusion When All Else Fails

Surgery to fuse the lumbar spine doesn't always work. Research shows it's getting better, with 80 percent success in the short run. This is up from the previously reported 50 percent. But there are still problems with pain from the bone graft, bracing, and unwanted motion at the fusion site.

If fusion is the last step in treatment, what can be done next? Try total disc replacement (TDR). The TDR implant preserves motion and normal spinal alignment. This prevents more damage in the spine. With a spinal fusion, the loss of motion at the fused area transfers the force and load to the level above or below it. The result is degeneration of these segments.

This is the longest study so far showing the results of TDR. Forty-two patients received a special replacement disc called a Prodisc prosthesis. They were followed for an average of eight years. Range of motion at the level of the disc replacement and damage at the levels above and below were measured.

The researchers report at least two-thirds of the patients kept their forward and backward motion in the low back area with a TDR. This is important. Without the motion, there's no difference between a TDR and a fusion. They found that women are less likely to have as much motion as men. The reasons for this are unclear.

The authors report that there are still a lot of unknowns in this area of research. How much motion is needed to avoid problems? Why do women tend to have less motion after TDR compared with men? How does the Prodisc model compare to others now on the market? How does TDR compare to fusion 10 or even 20 years later? More research is planned by these scientists to find some answers.

References: Russel C. Huang, et al. Long-Term Flexion-Extension Range of Motion of the Prodisc Total Disc Replacement. In Journal of Spinal Disorders. October 2003. Vol. 16. No. 5. Pp. 435-440.

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