Degenerative disc disease occurs when wear and tear on the intervertebral discs between the bones (vertebrae) in the spinal column cause deterioration that eventually results in pain. This disorder is associated with aging. It is among the most common sources of back pain in people who are middle-aged or older.

As they age, most people suffer some damage to their intervertebral discs, also known as spinal discs. Normally, these discs serve as shock absorbers between the bones of the spine and help the back to stay flexible. The discs are made up of two parts:

• Outer layer. This is the tough, fibrous covering (annulus fibrosis) of the disc.
  
  
• Core. Inside the outer layer is a soft, jelly-like core (nucleus pulposus). It contains about 80 percent water, which gives the core a sponge-like quality, making it better able to absorb spinal stress.

As people age, their spinal discs usually begin to slowly flatten, deteriorate, lose water content, and become thin and more brittle.

The deterioration from this aging process can leave spinal discs vulnerable to the type of injury known as degenerative disc disease. In this disorder, the outer layer of a spinal disc may tear. In some cases, the inner core of the disc may burst through the outer covering in a condition known as a herniated disc. These protrusions sometimes press on nerves, resulting in pain in the back and leg that can range from mild to excruciating.

Patients with degenerative disc disease usually experience several phases of symptoms, which can occur over several decades. Initially, acute back pain may make it difficult to move the back in a normal fashion. Then, the area where the injury occurred becomes inflamed, resulting in back pain that comes and goes over a period of time. Eventually, the body restabilizes the injured part of the back, and the patient usually experiences fewer episodes of back pain because fully degenerated discs have lost the substances (proteins) that caused inflammation and pain.

Degenerative disc disease is a condition that sometimes generates confusion. The medical community has yet to define degenerative disc disease precisely, so patients often encounter varying explanations of the disorder. In addition, many physicians consider the “disease” part of the name to be a misnomer. In reality, it is a degenerative condition that sometimes produces pain due to one or more damaged discs.