News Fusion Versus Artificial Disc Arthroplasty for Lumbar Degenerative Disc Disease Fusion surgery for Lumbar Degenerative Disc Disease (DDD) is a time honored, yet controversial treatment approach. Spinal fusion alleviates pain by removing inflammatory disc material and immobilizing the painful spinal segment. Decades of research has produced new technology that now offers an alternative to lumbar fusion. In October of 2004, the Food and Drug Administration (FDA) approved the first total disc replacement or TDR (Charite¢ Artificial Disc, DePuy Spine) for use in the United States. It is approved for use in one level DDD, specifically at either L4-5 or L5-S1. Since itÌs approval a little over a year ago, thousands of surgeons have been trained, but as with any new technology, only a subset of those surgeonÌs are offering the procedure to their patients. Whether it is offered by their surgeon or not, many people with low back pain are independently seeking information about the technology, hoping it may represent a new option in their quest to resolve their particular back pain issue. At the NeuroSpine Center of Wisconsin, we have been wary of Ïjumping on the bandwagonÓ with regard to this technology on account of our excellent clinical outcomes with lumbar fusion and because of what is known and unknown about artificial disc arthroplasty. There is hope that disc arthroplasty will be more efficacious than fusion surgery in treating chronic low back pain due to DDD. Although the pivotal study did demonstrate that patientÌs were more satisfied with the artificial disc than the fusion surgery (73% vs. 54%), only a little over half (57%) of the Charite¢ patients met the established criteria that would define them as having had a Ïsuccessful outcomeÓ. Outcome criteria included return to work, use of narcotics, pain scores and functional status among other things. If only half of the subjects were defined as a success, this would lead one to assume that TDR is not necessarily a reliable procedure. Another vexing problem with lumbar fusion is the issue of adjacent segment degeneration (ASD). When a motion segment is fused, mechanical stress is transferred to the adjacent segment which can in some cases result in ASD. Proponents of motion preservation believe that disc arthroplasty will reduce the incidence of ASD by decreasing the forces at the next, unfused level. However, the literature has not conclusively shown that a one level or even a two level lumbar fusion for degenerative disc disease greatly increases the chance of ASD. There are as many articles describing adjacent level breakdown as articles that refute the accelerated breakdown claims. Furthermore, an article presented at The North American Spine Society (NASS) 2005 Annual Meeting (Pimenta, Phillips) suggested that at 2 years, 50% of subjects who have had a disc arthroplasty do have evidence of accelerated degeneration in the posterior facet joints. Our focus at the NeuroSpine Center of Wisconsin has been to try to optimize surgical outcomes by improving preoperative patient selection. We have found that in approximately 4 out of 5 cases of DDD, patients require only a one level L5-S1 fusion. Fortunately at this level, there is minimal motion so fusing it does not significantly change the biomechanics of the spine. The two findings on an MRI that correlate best with a successful postoperative outcome is the presence of disc space collapse and cartilaginous endplate erosion. Findings such as a disc bulge, disc desiccation or an annular tear do not correlate well with a successful outcome. Discograms are rarely necessary and can often be misleading (both higher false positive and false negative results). Although surgery is not always necessary for patients with DDD, we have found one level ALIF surgery, especially at L5-S1, to be very reliable. It carries with it a low incidence of revision surgery. There has been almost no incidence of ASD and only about 3% will need later posterior stabilization. Using MRI findings of a collapsed disc space and cartilaginous end plate erosion, surgery should result in 85%-90% of patients enjoying significant relief of pain. Since TDRÌs effectively act like a spacer that preserves motion, we do not see a compelling reason for the use of TDRÌs at this time. Our own personal experience has been that an ALIF procedure can be accomplished in about 30 minutes with minimal blood loss. 70% of the patients are discharged the same day and 30% stay over night. We have had an 85-90% success rate. Of those, 75% of non-WorkersÌ Compensation patients reported little in the way of residual pain. Most patients can return to light duty work at 6 weeks and full duty at 12 weeks. After 12 weeks, patients rarely need activity restrictions. We know there is a lot of added expense and even danger associated with lumbar disc arthroplasty as compared with an anterior lumbar interbody fusion (ALIF). At NASS this year, there were reports of three deaths related to postoperative dislodgement (2 pulmonary emboli and one extravasation at the time of reoperation). This would appear to be a very high death rate for treatment of a benign condition in a young, healthy patient population A significant concern with any disc arthroplasty is how long the device will last before it wears out. There are some total disc replacements that were implanted nearly 17 years ago. Since TDR surgery is most often performed in a relatively young population of patients, the implants will need to function well for a minimum of 40-50 years. With only 17 years of experience, we donÌt know enough about how these will wear over time or how they will impact the usual age-related degenerative changes in the lumbar spine. . In summary, although lumbar artificial disc surgery may offer some advantages over a traditional one level ALIF, it should still be considered experimental. More clinical research is needed before it can claim superior results to ALIF , or that it will prevent adjacent segment degeneration. Peter F. Ullrich, Jr., MD For more information call 920-882-8200 or 1-888-231-5236 Back to News     5320 West Michaels Drive   |   Appleton, WI 54913-8400   |   Phone: (920) 882-8200 or (888) 231-5236   |   Fax: (920) 882-8210