Lumbar disc replacement surgery comes as a relief for all those patients suffering from severe discogenic back pain for several years. Discogenic back pain refers to pain in the low back and legs arising from compression of neural structures by degenerated disc fragments. The surgery aims at replacing the diseased disc with a prosthesis (artificial disc) that mimics the movement of the natural disc.
The lumbar spine refers to the lower segment of the human spine in the low back region. This segment consists of 5 short bones called vertebrae arranged over one another, separated by soft cushion like structures called as intervertebral discs. The low back is subjected to maximum load during all the movements of the human body as maximum movement occurs here. As a result it is vulnerable to degenerative changes in the disc as well as in the vertebrae. When the disc degenerates it loses its water content, shrinks in height and disintegrates into fragments and bulges. This may compress the nearby spinal nerves passing in its vicinity. Also reduced disc height results in reduced intervertebral distance, which puts pressure on the facet joints causing their hypertrophy (thickening).
Lumbar Disc Replacement Surgery
Compression of the spinal nerves due to thickened ligaments, bony spurs on the lower surface of vertebral bodies or due to prolapsed disc leads to pain in the back and radiating pain numbness and tingling in the legs. In longstanding cases there may also be weakness in the legs.
The procedure aims at replacing the diseased disc with a metal or plastic prosthesis which maintains normal spine movement. It also aims at restoring normal intervertebral distance and enlargement of narrowed intervertebral foramen thus relieving the compression of nerves.
Who may require Lumbar Disc Replacement Surgery
All those individual suffering from discogenic back pain as diagnosed by a combination of clinical symptoms of back pain, and radiating leg pain and diagnostic tests supported by radiological evidence of degenerative disc disease are ideally suited for this procedure. These patients must also have undertaken conservative treatment (bed rest, traction, physical therapy, medication) for a considerable period of time with no satisfactory results.
Details of the Surgery
Disc replacement surgery is done to stop the symptoms of degenerative disc disease. Discs wear out or degenerate as a natural part of aging and from stress and strain on the spine. Eventually, the problem disc collapses, which causes the vertebra above to sink toward the one below. This loss of disc height affects nearby structures - especially the facet joints.
When the disc collapses it no longer supports its share of the load in the spine. The facet joints of the spine begin to support more of the force that is transmitted between each vertebra. This increases the wear and tear on the articular cartilage that covers the surface of the joints. The articular cartilage is the smooth, slippery surface that covers the surface of the bone in any joint in the body. Articular cartilage is tough, but it does not tolerate abnormal pressure well for long. When damaged, articular cartilage does not have the ability to heal. This wear and tear is what is commonly referred to as arthritis.
Shrinking disc height also reduces the size of the neural foramina, the openings between each vertebral pair where the nerve roots leave the spinal column. The arthritis also results in the development of bone spurs that may protrude into these openings further narrowing the space that the nerves have to exit the spinal canal. The nerve roots can end up getting squeezed where they pass through the neural foramina.
Replacing the damaged disc with an artificial disc, or implant, called a prosthesis can restore the normal distance between the two vertebrae. The artificial disc sits between the two vertebrae and distracts or jacks up the upper vertebra. Enlarging the disc space relieves pressure on the facet joints. It also opens up the space around the spinal nerve roots where they pass through the neural foramina.
Another benefit of the artificial disc replacement is that it mimics a healthy disc. Natural motion is preserved in the spine where the new disc is implanted. And it helps maintain stability in the spinal joints above and below it.
Who can benefit from this procedure?
For many years, the standard of care for chronic pain from a degenerated disc has been spinal fusion surgery. Bone graft donated by a bone bank or taken from your pelvic bone is used to fuse two or more vertebral bones together. The spine is stabilized but you will lose motion at that level. The increased stress on the next lumbar vertebra can cause problems later.
The artificial disc replacement is used to reduce or eliminate the pain while still allowing motion. One advantage of the artificial disc is that it may also prevent premature breakdown of adjacent levels of the lumbar spine.
You may be a good candidate for a lumbar artificial disc replacement if you have chronic pain and disability from lumbar disc degeneration despite nonoperative treatment for at least six months. The artificial disc replacement provides an alternative to spinal fusion. The device helps restore the normal space between two vertebrae. You will still have movement at the level where the ADR is implanted.
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