Artificial Disc Replacement
What You Should Know about This Surgical Technique
Question: I want to learn more about artificial disc replacement surgery. It seems like this is a fairly new technique, but are there any updates I should know about?
— Morristown, NJ
Answer: Actually, this is not such a new technique. Artificial disc replacement surgery was first developed in Europe in the mid to late 1980s as an alternative to spinal fusion and has been used there clinically for more than 20 years. We first started studying the artificial disc in the United States with the Food and Drug Administration (FDA) trial of the Charité disc replacement in March 2000. In fact, surgeons at the Texas Back Institute, where I practice, performed the first artificial disc replacement at as part of the FDA clinical study.
Lumbar Artificial Discs—What Is FDA-approved?
The Charité artificial disc was FDA-approved in October 2004. The Charité artificial disc has been used for 10 years. In fact, I with my co-investigators from the IDE trial published the 5-year results of the Charité last year.
There is a second artificial disc that is also FDA-approved for use in the US, and this is called the ProDisc. It was developed in the late 1980s in Europe and has been used there since that time.
The clinical study for the ProDisc artificial disc began in 2001 and was approved for clinical use in the US in August 2006. There are also now 5-year results of the ProDisc disc replacement that show maintenance of success rate and a very low complication and re-operation rate.
Both the Charité and ProDisc artificial discs are made of similar materials, a combination of metal and plastic. These devices try to reproduce the normal motion of the disc itself, although there are slight biomechanical differences between the two devices.
Cervical Artificial Discs—What Is FDA-approved?
For the cervical spine, there are 3 artificial discs approved. The first is the ProDisc C, which is made of metal and plastic. The second is the Bryan disc, which is made of a compressible material. The third is the Prestige disc, which is made of stainless steel.
Artificial disc replacement for the cervical spine is for patients who have arm pain or may have compression of their spinal cord. More insurance companies will pay for cervical disc replacement; fewer will pay for lumbar disc replacement.
Artificial Discs Awaiting FDA Approval
There are several other devices that are still in the process of gaining approval by the FDA. These include the Flexicore, the Maverick, and the Kineflex, all of which are metal-on-metal discs for the lumbar spine.
There are also several other newer generation disc replacements that are currently being studied. An example of a newer generation disc includes the Axiomed Freedom lumbar disc, which is made of a compressible material very similar to a natural disc.
An Experimental Treatment?
Despite the fact that artificial disc replacement has been used successfully and with a very low rate of complication, there are still many insurance companies that consider this procedure experimental.
There are subtle variations between the artificial discs, but in general, all of the patients in the clinical studies show the same general results—approximately 90% of patients achieve a 50% reduction of pain and a 50% improvement of their functional activities, on average. The results are very similar to spinal fusion.
Advantages of Artificial Disc Replacement
The main advantage of artificial disc replacement over spinal fusion is that it may place less biomechanical stresses on the adjacent disc. I am sure that many of you have heard of friends who have had one spinal fusion, only to go back and have another fusion. The 10-year data from Europe, Australia, and our early data in the US shows that the revision rate at 10 years remains at about 10%. What that means is that only about 10% of patients require a second surgery. This is in contrast to many studies for spinal fusion that show that the additional surgery rate at 10 years can be as high as 20% to 40%.
Other advantages include faster recovery and return to normal activities. Most artificial disc replacement patients return to work in 1 to 2 weeks and can resume normal activities (excluding sport activities) after 8 to 12 weeks. This is in contrast to fusion patients who may be restricted in their activities for up to 6 months or more. The 5-year Charité study showed that, statistically, more artificial disc replacement patients were able to work sooner compared to the fusion patients.
Both lumbar and cervical artificial disc replacement represent a move away from spinal fusion and toward giving the patient more successful surgical outcomes.