Topic Overview

What is degenerative disc disease?

Degenerative disc disease is not really a disease but a term used to describe the normal changes in your spinal discs as you age. Spinal discs are soft, compressible discs that separate the interlocking bones (vertebrae) that make up the spine. The discs act as shock absorbers for the spine, allowing it to flex, bend, and twist. Degenerative disc disease can take place throughout the spine, but it most often occurs in the discs in the lower back (lumbar region) and the neck (cervical region).

See a picture of the spine and the discs in your spine.

The changes in the discs can result in back or neck pain and/or:

• Osteoarthritis, the breakdown of the tissue (cartilage) that protects and cushions joints.
• Herniated disc, an abnormal bulge or breaking open of a spinal disc.
• Spinal stenosis, the narrowing of the spinal canal, the open space in the spine that holds the spinal cord.

These conditions may put pressure on the spinal cord and nerves, leading to pain and possibly affecting nerve function.

What causes degenerative disc disease?

As we age, our spinal discs break down, or degenerate, which may result in degenerative disc disease in some people. These age-related changes include:

• The loss of fluid in your discs. This reduces the ability of the discs to act as shock absorbers and makes them less flexible. Loss of fluid also makes the disc thinner and narrows the distance between the vertebrae.
• Tiny tears or cracks in the outer layer (annulus or capsule) of the disc. The jellylike material inside the disc (nucleus) may be forced out through the tears or cracks in the capsule, which causes the disc to bulge, break open (rupture), or break into fragments.

These changes are more likely to occur in people who smoke cigarettes and those who do heavy physical work (such as repeated heavy lifting). People who are obese are also more likely to have symptoms of degenerative disc disease.

A sudden (acute) injury leading to a herniated disc (such as a fall) may also begin the degeneration process.

As the space between the vertebrae gets smaller, there is less padding between them, and the spine becomes less stable. The body reacts to this by constructing bony growths called bone spurs (osteophytes). Bone spurs can put pressure on the spinal nerve roots or spinal cord, resulting in pain and affecting nerve function.