What Is Lumbar Disc Disease (Herniated Disc, Ruptured Disc or Slipped Disc)?

As we age, the intervertebral disc may lose water and become dried out. As this happens, the disc compresses. This may lead to the deterioration of the tough outer ring allowing the nucleus, or the inside of the ring, to bulge out. This is considered a bulging disc.

As the disc continues to degenerate, or with continued stress on the spine, the inner nucleus pulposus may actually rupture out from the annulus. This is considered a ruptured, or herniated, disc, often called a slipped disc. The fragments of disc material can then press on the nerve roots that are located just behind the disc space.  Herniated discs can cause pain, weakness, numbness, or changes in sensation.

Most herniated discs are found at the lower lumbar spine, especially at the L4-5 and L5-S1 levels. About 12 million Americans have degenerative disc disease.

Anatomy of the lumbar spine

The vertebral column, also called the backbone, is made up of 33 vertebrae that are separated by spongy disks and classified into four distinct areas. The cervical area consists of seven bony parts in the neck; the thoracic spine consists of 12 bony parts in the back area; the lumbar spine consists of five bony segments in the lower back area; five sacral bones (fused into one bone, the sacrum); and four coccygeal bones (fused into one bone, the coccyx).

Lumbar disc disease occurs in the lumbar area of the spine. The lumbar area of the spine (and other areas of the spine) is made up of two parts, including the following:

• Vertebral bodies - the parts that are made of bone.
• Intervertebral discs - also known as the discs; the discs are located between the bony parts of the spine and act as "shock absorbers" for the spine.

The vertebral bodies are numbered from 1 to 5 in the lumbar spine and the discs are located between two of the vertebral bodies and are numbered accordingly (such as a disc at L2-3, or between the lumbar discs numbered 2 and 3).

The intervertebral disc is composed of two parts, including the following:

• Annulus fibrosis - a tough outer ring of fibrous tissue.
• Nucleus pulposus - located inside the annulus fibrosis; a more gelatinous or soft material.