Long-term Lumbar (Low Back) Artificial Disc Studies Show Positive Results
An Interview with Jack Zigler, MD
SpineUniverse: What are surgeons learning about lumbar artificial disc implantation after years of use and long-term data?
The IDE studies allow us to consistently follow these patients for many years. We now have five-year data and published follow-up on the original cohorts (groups) of patients who were enrolled and randomized. One-third received spinal fusion and two-thirds received the lumbar ProDisc.
We’ve found that in patients with single-level lumbar degenerative disc disease, who had either fusion or ProDisc-L procedures, both groups experienced dramatic improvement after surgery, and that improvement was durable for five years. Their conditions have not worsened in the five or more years we’ve been following these patients.
This outcome validated surgery as a very reasonable treatment option for patients with single-level lumbar degenerative disc disease who have failed at least six months of non-operative therapy. In the ProDisc study patients, the average was nine months of failed non-surgical treatment.
Therefore, over the course of six to nine months, if a patient is not getting better with the therapies that help most people—that being rest, physical therapy, spinal injections, and/or anti-inflammatory medication—we have very good validation that surgery can help.
SpineUniverse: What does the data reveal about patient satisfaction with lumbar disc replacement?
At every one of the data points that we evaluated, the ProDisc patients always did a bit better than the spinal fusion patients, although not always statistically significant. We also know that after two years and five years, an overwhelming majority of patients were satisfied and would have had the procedure again if they needed it.
We know that patients with an artificial disc go back to work faster, have better range of motion, and use fewer narcotics and muscle relaxers than patients who had fusions. Furthermore, from the five-year data, there is a dramatic decrease in adjacent level degeneration in the patients with the ProDisc versus the patients with a fusion. That difference was about 3:1.
SpineUniverse: Are there other reasons why the data is so significant?
We think that over a longer period of observation, the results will translate into a significant decrease in re-operations or operations at adjacent vertebral levels. So far, there is a difference, but it’s not statistically significant because the numbers are too small. However, we think in 10 to 15 years from surgery, the change we see radiographically (eg, on x-ray evaluation) will translate into a reduced need for adjacent level surgery, which will be a huge advantage for artificial discs.
SpineUniverse: Is there a concern about, or issues of device subsidence (eg, loosening)?
The occurrence of artificial disc subsidence is not greater than in spinal fusions. In a well-performed fusion or a well-performed artificial disc implantation procedure, subsidence is rare.
Remember, not every patient is a good candidate for spinal fusion or an artificial disc. We are scrupulous in working up each patient before surgery is considered. At Texas Back, all patients undergo a pre-operative DEXA scan to measure bone mineral density. A patient who has severe osteopenia or is diagnosed with osteoporosis is not offered the artificial disc because we know the subsidence risk is high and the outcome may not be good.