Two years ago, I considered having a disc replacement. There just wasn't enough evidence to satisfy me that these new implants were really the way to go. I had a fusion instead. I keep wondering if I made the right decision. What's the status of this new treatment now?
Five years ago (in 2004), the Food and Drug Administration (FDA) approved the CHARITÃ artificial disc. This approval was made based on a two-year trial conducted by orthopedic surgeons at 14 different clinics around the United States. The first five-year results for the same patients are now available. This is the largest and longest randomized, multicenter study of artificial discs published in the United States so far.
All patients receiving the artificial disc had severe back pain. They had all tried (and failed to improve with) six months or more of conservative (nonoperative) care. The diagnosis for everyone was degenerative disc disease. Only patients with single-level disease between L4 and S1 were included.
The patients were randomly divided into two groups. One group was treated with a spinal fusion at the affected level. The second group had the damaged disc removed and replaced with an artificial disc device.
Various measures were used to study the outcomes. Pain, range-of-motion, function, disability, work
status, and reoperation rates were all compared between the two groups. For the most part, they found similar results in both groups. The same number of patients improved at the same time and in the same amount in both groups.
This isn't the result they were expecting. In theory, the artificial disc replacement should produce better results than a fusion. In reality, only slightly more than half the group had improved function and that was very minimal.
There was some question raised that maybe the similarity of results was because of differences in patients in each group. But the groups were very similar in terms of race, age, weight, activity level, and work status before surgery. The only significant difference was the larger number of patients in the disc replacement group who had prior (minor) back surgery. The CHARITÃ group was also more likely to be working full-time before surgery compared with the fusion group.
Independent reviewers of the study suggested that the results weren't really acceptable for either treatment (fusion or disc replacement). And the fact that the patients chosen for either surgery were highly selected raised some questions, too. If patients were so carefully selected but didn't really get the hoped for results, what does that suggest?
Although the authors say the disc replacement is safe and effective for this patient population, the editors advised caution. They suggested future studies are needed to look at some of these problems and answer the difficult questions raised before giving artificial disc replacements the green light as safe and effective for long-term use.