ARTIFICIAL DISC REPLACEMENT in the LUMBAR SPINE
Low back pain is a significant cause of disability in the U.S. and worldwide. It is estimated that 70% to 80% of people will experience low back pain at some point in their lives.
Artificial disc replacement is a newer surgical procedure for relieving low back pain. Similar to hip or knee joint replacements, a disc replacement substitutes a mechanical device for an intervertebral disc in the spine. The device is meant to restore motion to the spine by replacing the worn, degenerated disc.
This technology has been available in Europe for over a decade. Artificial disc replacement initially gained FDA approval for use in the U.S. in 2004. Over the past several years, numerous other disc replacement designs have been developed and are currently being tested (AAOS, 2015).
To determine who is a good candidate for disc replacement, the surgeon may require a few tests. These may include magnetic resonance imaging (MRI), discography, computed tomography (CT or CAT scan), and x-rays. These tests will also help the surgeon determine the source of the pain.
Good candidates for disc replacement have the following:
- Back pain thought to be caused mostly from one or two intervertebral discs in the lumbar spine
- No significant facet joint disease or bony compression on nerves
- Not excessively overweight
- No prior major surgery in the lumbar spine
- No deformity (scoliosis)
TREATMENT & BENEFITS
Artificial disc replacement has emerged as an alternative treatment option to lumbar fusion surgery for low back pain.
Lumbar fusion surgery remains the “gold standard” for treating low back pain patients who are not helped by nonsurgical methods and many people find relief with lumbar fusion, however the results of fusion surgery vary. For example, a patient with spinal stenosis who has a fusion procedure may have a very different outcome from a patient who has a fusion to help back pain that is caused by disc degeneration. In addition, some patients whose fusion surgeries heal perfectly still end up with no improvement of their back pain.
The artificial disc offers several theoretical benefits over the spinal fusion for chronic back pain, including:
- Potentially enhanced clinical success rates (pain reduction)
- Potential to avoid premature degeneration at adjacent levels of the spine by maintaining normal spinal motion
The surgical implantation procedure is performed through an incision in the abdomen (similar to an anterior lumbar interbody fusion).
With this approach, the organs and blood vessels must be moved to the side. This allows your surgeon to access the spine without moving the nerves.
Usually, a vascular surgeon assists the orthopaedic surgeon with opening and exposing the disc space. Most surgeries take about 2 to 3 hours.
The disc replacement device may comprise the nucleus (center) of the disc while leaving the annulus (outer ring) in place, although this technology is still in an investigative stage.
In most cases, total artificial disc replacements substitute the annulus and nucleus with a mechanical device that will simulate spinal function.
There are a number of different disc designs. Each is unique in its own way, but all maintain a similar goal: to reproduce the size and function of a normal intervertebral disc.
Some of the discs are made of metal, while others are a combination metal and plastic, similar to joint replacements in the knee and hip. Materials used include medical grade plastic (polyethylene) and medical grade cobalt chromium or titanium alloy.