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Low Back Pain and Artificial Disc Replacement

Peer Reviewed

Low back pain is a significant problem that affects many Americans. Today, we have several procedures to treat patients who have failed all non-operative management. Recently, the Food and Drug Administration (FDA) approved an artificial disc for the treatment of low back pain (CHARITÉ™ Artificial Disc, DePuy Spine, Inc.). In addition, other artificial disc devices developed by other companies expect to be FDA-approved and subsequently come to market. These devices will provide surgeons options when selecting an artificial disc device.

Disc Replacement Explained
Artificial disc replacement is the actual removal of the disc (intervertebral disc) through an incision made through the abdomen(anterior approach). The disc is completely removed and the prosthesis (artificial disc) is positioned and implanted between the two vertebral bodies.

spinal column
Spinal Anatomy: A disc lies between two vertebral
bodies; this may be called a ‘motion segment’

This prosthesis is analogous to one used in knee or hip replacement. These devices are often a metal-on-metal design that restores and maintains normal motion. The benefit of artificial disc replacement is that it maintains normal spinal motion and spares the patient from having the 'motion' segment fused.

To explain this further, in the lumbar spine there are five motion segments. Each motion segment consists of two bones (vertebrae) with a disc in between. Located behind the vertebrae and discs are small joints (facet joints). The facet joints are similar to joints elsewhere in the body that allow the motion of bending forward and backward.

facet joints

Goals and Benefits of Artificial Disc Replacement
The goal of an artificial disc is to remove the pain generator; that being a degenerated or damaged disc. After the degenerated disc is removed, the artificial disc is implanted into the empty space and maintains the motion of that particular motion segment. The benefits include:

1. Avoids disrupting the segment above or below the disc, which preserves the natural anatomy of the unaffected lumbar discs.

2. Allows the surgeon to restore normal disc height and post-operatively allows the patient more flexibility to bend forward, backward, and rotate or twist.

Disc Replacement: Better than Spinal Fusion?
Total disc or artificial disc replacement is not a soft material and an artificial disc does not restore or replace a human disc. An artificial disc is a prosthetic device made from metal and is sometimes designed with a plastic liner or core that helps to maintain the body's ability to flex and extend. Through the FDA's trial studies, it was found that patients who underwent artificial disc replacement did experience a quicker post-operative return to normal functional activity. This is definitely a benefit.

However, artificial disc replacement is not for all patients with low back pain and it does not replace the need for spinal fusion. Lumbar spinal fusion, which is a common treatment for patients with low back pain who have failed non-operative management, is effective in reducing pain. The disadvantage of spinal fusion is it limits the patient's range of motion and may transfer stress to the discs above and/or below the fused segment.

Making Decisions
Patients who are interested in exploring artificial disc replacement as a treatment option should seek a well-qualified surgeon with vast experience in performing anterior (through the stomach) spine surgery. Artificial disc replacement is similar to any major surgical procedure. There are possible complications that include unresolved back pain, prosthesis failure, bowel or bladder problems, and the need to revise the prosthetic device at a later date.

Technology Marches On
The clinical trials, those presently completed, have proven that artificial disc replacement not only maintains spinal flexibility, but also reduces pain and restores function to patients who suffer low back pain. No doubt -- future improvements in technology and surgical techniques, along with a better understanding of natural anatomy, will expand the indications for use of total disc replacement.

Updated on: 09/07/12
Steven R. Garfin, MD

Not all patients with low back pain are candidates for an artificial disc replacement. It should not be perceived as a panacea for everyone with chronic back pain. The current clinical results, as assessed through FDA approved controlled trials, show that after 6 to 12 months the clinical results following an artificial disc replacement compared to a one or two level fusion are similar, assuming the fusion heals. But the early results following surgery, to return for work and function, strongly favor the artificial disc. Artificial disc replacement surgery does appear to be easier to perform, as well as to recover from. The results appear to be reliable and consistent over the 2-year follow-up period study. However, it needs to be emphasized that it is only indicated for use in selected patients with low back pain that do not respond to normal nonoperative means. Most patients with chronic back pain will not be candidates for any surgery. Of those that are, some may still benefit from a fusion rather than an artificial disc. Additionally, the motion maintained from a one-level artificial disc replacement is not necessarily normal in the human once implanted. Clinically (functionally) a patient may not be able to tell the difference whether they had a successful 1- level fusion or an artificial disc at one year, as the outward motions (not radiographic) may be identical. Long-term follow-up is necessary, and undergoing.

The artificial disc is an exciting new technology and opportunity for patients. Emphasis, however, has to be on patient selection and indications. Again, this is not a treatment for all patients with chronic low back pain. The surgical success is in the 70 - 80% range, which is not dissimilar from a solid fusion in the right setting with the right indications, which is low back pain from a degenerative disc, assuming the source can be localized and determined.

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