Degenerative disc disease can occur in any region of the spine; however, it most commonly occurs in the lumbar spine. Doctors are not sure of the exact cause of degenerative disc disease, but it appears that aging, trauma, and arthritis contribute to this condition. Doctors suspect that genetic, environmental, and autoimmune factors play a role as well. Additionally, lifestyle factors, such as smoking, or strenuous repetitive activities, such as gymnastics or lifting, may lead to degenerative disc disease. Degenerative disc disease develops most frequently in middle-aged or young adults with active lifestyles.
Physical changes in the disc occur with the natural aging process. With advancing age, discs lose water content and become narrower, less flexible, and less effective as cushions between the vertebrae. As a disc deteriorates, the outer layer can weaken and tear. Discs heal slowly, during which time new nerve endings may form in the torn area. Contact with the new nerve endings can cause irritation and pain.
A healthy disc acts as a cushion between the vertebrae. However, when a disc degenerates, painful bone on bone rubbing can occur. This can lead to changes in the spine structure that cause pain and impairs movement and function.
Without the protective disc, the spine can become structurally unstable and unable to tolerate stress, which may lead to other painful spine conditions including a herniated disc, spondylolisthesis, and spinal stenosis. A herniated disc occurs when the outer layer of the disc (annulus) ruptures and the inner contents (nucleus pulposus) comes out. Pain, irritation, and swelling results when the inner contents contact the spinal cord or spinal nerves. Spondylolisthesis is a spine condition that occurs when one vertebra shifts forward out of place. Spinal stenosis is a type of spine condition that results when the facet joints and ligaments enlarge, narrowing the space inside of the spinal canal.