Degenerative disc disease is a condition that involves weakening of one or more vertebral discs which normally act as a cushion between the vertebrae. This can occur anywhere in the spine. This condition can develop as a natural part of the aging process but may also result from an injury to the back or neck. Degenerative disc disease typically begins when small tears appear in the disc wall called the annulus. Individual lamellae collagen fibers make up the annulus. Tears in the lamellae are referred to as annular tears or as a 'torn disc'. When the disc degenerates the disc begins to lose many of its properties that make it a good shock absorber. For some people these tears can cause considerable pain and spasms. Just like other tissues in our bodies, the disc heals over several weeks by creating scar tissue however scar tissue is not as strong as the original disc wall.
Over time, with repeated neck or back injuries, the process of tearing and scarring may weaken the disc wall. As people age, the nucleus pulposus (center of the disc) becomes damaged and loses its water content. This fluid is needed to keep the disc functioning as a shock absorber. If the nucleus pulposus is not able to act as a cushion, the nucleus collapses and the vertebrae above and below the damaged disc slide closer together. This improper alignment causes the facet joints (the areas where the vertebrae touch) to twist due to an unnatural position. In time, this awkward positioning of the vertebrae may create bone spurs or osteophytes. If bone spurs grow into the spinal canal, they may pinch the spinal cord and nerves, a condition called spinal stenosis. If the outer annulus tears and a piece of the nucleus pulposus moves through the tear, a disc herniation may pinch the spinal cord and nerves. The site of the injury may be painful. Some people experience a radiculopathy as pain, numbness, or tingling in the arms or legs.
Dr. Thomas Schuler further explains common causes of back and neck pain. He differentiates sprains and strains, and discuses how disc degeneration can lead to chronic back pain. He defines active and passive stabilizers known as fractures (spondylolysis and slippage (spondylolisthesis).