When Shopping for Disc Surgery...

Photo: FDA

Disc problems, such as herniated or bulging discs, and degenerative disc disease are common maladies that can cause back and neck pain, sciatica, and/or pain down the arms. Spinal fusion has been the surgery of choice for years for such problems. More recently, the artificial disk replacement has come on the scene. In 2004 the FDA approved for market the first artificial disk – the Charite, made by De Puy, for the lumbar spine. In 2007, they began approving artificial disks for the neck. The neck is trickier to operate on, and this is probably why the manufacturing of cervical disks has come a few years later than discs for the low back.

Total disc replacement is still a relatively new surgery. The goal is to take out all the disc material in between two vertebrae and put a moveable device in its place. The artificial disc addresses one of the problems with spinal fusion – the limitation of movement at the place where the surgery is done, which may, in turn, cause problems in spinal joints above and below the surgical area, later.

So the artificial disk replacement sounds like a good idea, perhaps? After all, it will allow you to move your spine and it is supposed to take away the pain immediately. If you are considering a disc replacement surgery, slow down. Studies on the artificial disc are sketchy, in more ways than one.

First of all, be sure you are a good candidate for this new type of surgery. The American Association of Orthopedic Surgeons says if you are an ideal candidate for an artificial disc replacement you will have the following characteristics:

• Your doctor thinks your back pain is caused mostly from one or two disks in your low back.
• You don’t have facet joint problems. (The disc replacement surgery sometimes causes facet joint problems.)
• There aren’t any bones pressing on your nerves.
• You are not obese or grossly overweight.
• You’ve never had a major spine surgery before.
• You do not have scoliosis, or other spinal deformity.

Also, the FDA will not allow an artificial disc device to be placed in the spine of a patient who has osteoporosis. In the human body, ligaments help hold the disk in place. In a disc replacement surgery, the device is essentially nailed to the vertebral bones, which, obviously, will need to be very strong.

Next, recognize that because this surgery is still quite new, not all the questions have been answered. There are few, if any long term studies that have looked to see if the pain stays away beyond the two year mark. Also, device failures do happen. And, surgeons need to be trained in the technique before they can perform it well.

Before an artificial disk can go on the market and be used in surgeries, it is the subject of a clinical trial done to assess its safety and effectiveness. Medtronic’s Prestige Cervical Disc, for example, was approved in July of 2007, after a 2 year trial involving 541 patients altogether. Two hundred seventy six of them had a disc replacement – the others served as a control group, for comparison purposes. Based on the results of the study, the FDA approved the device. But most people would want to know that a neck surgery will relieve their pain for much longer than two years. So the company is now required by the FDA to conduct post market research for 7 more years. This is true for all artificial disc manufacturers in the US.

This leads me to mention another problem -- the potential loss of objectivity in the original research process. Researchers from the clinical trial for ProDisc, a device made by Synthes, are now under scrutiny by the FDA for not having disclosed their financial ties to the manufacturer. The New York Times has the full story on that one. What this might mean to you is that if you are considering a disk replacement upon the recommendation of your doctor, the safety indicated by the very test that gave the green light for the product in the first place may indeed not really be there, as the researchers have an invested interest to see the ProDisc device succeed.

Discuss this issue in the Back and Neck Pain forum.