Determining Status of Discs Around Area to Be Fused Does Not Appear to Affect Surgery Outcome
People in modern society have a high incidence of chronic lower back pain. The increasing number of patients who suffer from this pain is causing problems socially and economically because of its effect on ability to work and cost on the healthcare system. This is leading researchers to work to find the best methods for diagnosing back pain and the most effective treatments.

One treatment for chronic lower back pain is spinal fusion, or surgery to fuse the discs that are causing the pain. In this cohort study, researchers looked at patients who were undergoing lumbar fusion for chronic lower back pain to find if evaluating the discs adjacent to those to be fused would make a difference in the outcome of fusion surgery.

Discovering if discs are causing pain isn't simple. X-rays and imaging (magnetic resonance imaging and computed tomography imaging) may show if there has been degeneration, but can't show if the discs are causing pain. A test called the provocative lumbar discography uses an injection into the spine to trigger pain if there is a problem with the disc.

According to the study authors, use of provocative lumbar discography is controversial and has not yet been consistently established as valid. The pain response from the injection is very subjective and the authors say, "discography is not a test at the level of a gold standard to identify whether a disc is truly a clinically significant pain generator in a chronic LBP patient."

In this study, the patients first underwent the discography and then a temporary transpedicular fixation, a test that could provide temporary relief from back pain. The results of this test determined whether the patients would receive fusion surgery or continue with conservative management.

Eight-two patients had surgery. Following the surgery, the patients rated their pain from 0 (no pain) to 100 (excruciating pain); this was compared to their ratings prior to surgery. The researchers found that the patients who were identified as having degenerating discs adjacent to the fused discs had no different outcome from surgery than did those patients who had normal adjacent discs.

The authors point out that the study was small and there were some weaknesses in the study design, including the discography, because of the many variables in the procedure. As well, the authors state that there may have been possible bias in the selection of the patient groups. However, despite the drawbacks to the study, the findings did indicate that the pre-operative status of the adjacent discs did not appear to be relevant to patient outcome following fusion surgery.
Paul C. Willems, MD, et al. Provocative Discography and Lumbar Fusion. In Spine. May 2007. Vol. 32. No. 10. p. 1094-1099.