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Clinical Results of Two Total Disc Replacements Compared

Total disc replacement (TDR) may replace spinal fusion for patients with disc disease. Studies are being done to track patients' short-term to long-term results. In this study, the clinical results of two TDR devices are compared.

Clinical results refer to patient recovery and function. This is an important distinction because many studies use radiologic results as the main measure of success. How the patient looks on X-ray and how he or she feels are two different standards of measure to consider.

The first disc device used in this study is the CHARITÉ. It has six spikes on the endplates to hold it in place. The second is the ProDisc model. Instead of spikes, it has a central keel to keep it stable. The ProDisc is easier to insert and to get a good position.

Results were compared between the two TDRs by measuring motion, function, and pain. The authors also looked at the condition of the joints and discs at the adjacent levels (above and below the TDR level).

Recovery rates and levels of back pain weren't different between the two groups. Success rates measured by improved function and patient satisfaction were the same among all the patients. Lumbar range of motion was less in patients with the ProDisc implant.

While comparing the results of these two disc replacements, the surgeons made an important discovery. No matter what kind of TDR was used, there was a significant amount of joint and disc degeneration. The changes were most obvious at the level above the TDR.

These results suggest further study is needed of the long-term results for TDRs. Implant design may be part of the problem. It's not clear yet whether changes seen on X-rays and MRIs will become symptomatic later on. These two groups will remain in the study to assess results after 10 years.

References: Chan Shik Shim, MD, PhD, et al. CHARITÉ Versus ProDisc. A Comparative Study of a Minimum 3-Year Follow-up. In Spine. April 20, 2007. Vol. 32. No. 9. Pp. 1012-1018.

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