Degenerative Disc Disease
Between each pair of vertebrae in the spine lies a shock-absorbing cushion called an inter-vertebral disc. As the body ages, the degeneration of these discs results from routine “wear and tear.” Everything you do while upright tests the spine’s ability to support your body weight and puts pressure on the discs. In addition, many people sustain minor injuries to the disc, injuries that may not cause any immediate pain. Over the years, these repeated daily stresses and minor injuries can add up, gradually causing “degenerative disc disease.” Although it starts with damage to one or more disc(s), degenerative disc disease eventually affects all parts of the spine surrounding the damaged disc(s).
The most common early symptom of degenerative disc disease is back pain that often spreads to the buttocks and upper thighs. The degenerating disc(s) can also cause “discogenic” pain (which just means pain that originates in a damaged disc) and bulging discs.
Every healthy inter-vertebral disc has two core components: a gelatinous center (the nucleus pulposus) and an outer ring of tough ligament material (the annulus). The nucleus has a jelly quality that allows it to absorb stress. The tough ligaments of the annulus hold the vertebrae together.
In minor disc injuries that result from daily wear and tear, the annulus is generally first to be injured. For example, the ligament may tear slightly. As these tears heal, scar tissue forms. Since scar tissue is not as strong as normal ligament tissue, as more scar tissue forms, the annulus becomes weaker. This may lead to damage of the nucleus. The nucleus may, for example, lose water content, compromising the disc’s ability to act as a cushion. This reduction in cushioning increases stresses on the annulus, leading to still more tears to the ligaments. As this cycle of degeneration continues, the disc’s nucleus may lose all its water. If the nucleus collapses in this way, the space between the vertebrae above and below the degenerating disc will narrow. As a result, the facet joints (located at the back of the spine) will shift, distorting the way these joints work together.
In addition, “bone spurs” (sometimes called osteophytes) may form around the damaged disc space or the facet joints. These bone spurs are thought to be the body’s natural response, an attempt to stop the excess motion at the affected spinal segment. But bone spurs on the spine can become a problem if they start to grow into the spinal canal and press into the spinal cord and spinal nerves. This condition is called spinal stenosis.
Since back pain may result from many different possible causes, the doctor will first need to take a complete history and administer a physical exam. To determine the root cause of your problem, the doctor will likely order such diagnostic tests as X-rays and/or an MRI. If your doctor suspects disc degeneration, X-rays can confirm a decrease in the space between vertebrae, the formation of bone spurs, facet joint hypertrophy (enlargement), or instability when flexing or extending your limbs. An MRI can verify loss of water in a disc, facet joint hypertrophy, spinal stenosis, or a herniated disc.
Spinal discs degenerate in virtually everyone as they grow older. In most cases, appropriate exercise, some modification of activities, and physical therapy that emphasizes proper body mechanics will be sufficient to eliminate or reduce the resultant back pain. Medications such as Motrin or Alleve may also be helpful to reduce inflammation. Only rarely will surgery be necessary.