A degenerated disc may occur due to degenerative changes in the annulus fibrosus or nucleus pulposus, resulting in discogenic pain, slipped disc, or soft tissue injury to the spine.
A degenerated disc is an intervetrebral disc in the spine that has undergone changes, affecting it's structural integrity and possibly negatively affecting the structures that it protects. A spinal disc, also known as an intervertebral disc, is a soft tissue of that protects and separates the vertebral bones of the spine. the discs of the spine are composed of an outer annulus fibrosus, and an inner core called the nucleus pulposus. The inner nucleus pulposus has a composition and shape of a gel pack. Because of the malleable nature of this gel-like inner core, the discs are able to support movement of the spine, as well as provide a cushion against pressures and downward movement. The outer annulus fibrosus is composed of rings and layers of fibrous rings that cross-cross one another to make for a very solid outer layer. When the discs of the back are healthy, the vertebral bones remain well protected and separated from one another, and the spine is stable.
Patients may experience lower back pain, either directly or indirectly as a result of degenerative changes to the discs. When we are young, the wall of the disc remains very strong, and there is enough material in the nucleus to keep the disc fully inflated. When we get older, the disc begins to dry out in the nucleus, reducing the amount of material in the disc, shrinking it. The outside of the discs also begins to wear out, thinning at its outer wall. Both of these types of changes to a degenerated disc may cause nerve problems, instability of the spine, and pain.
One of the most well known changes that may occur in discs is a herniated disc, also known as a slipped disc, This occurs when the annulus frays to the point that the outer wall bulges outwards or tears altogether. Bulges in the wall of the annulus are known as bulging discs. Tears in the discs are known as herniated discs.
A degenerated disc can cause pain in one of two ways. Pain may come directly as a result of pain sensitive nerves in the disc that responds to degenerative changes. Pain may also result from a bulging of the disc wall that occurs with a bulging disc, or due to herniated disc materials that are ejected out of the disc and into the nearby nerve root.
Typically, degenerative changes occur first in the nucleus of the disc, as it begins to dry out as we approach middle age. Repetitive trauma or strained ligaments may accelerate these age-related changes to the nucleus of the disc. As the inside of the disc begins to shrink in size, this change may trigger changes on the outside of the disc in response. Abnormal fibrous tissue may begin to develop on the annulus. These changes to both sections of the disc may increase abnormal fibrosus, and the growth of highly vascular reparative tissue into the substance of the disc itself.
These changes to a degenerated disc may cause the outer envelop of the disc to weaken and become more prone to tearing. This tearing of the disc may open to the point of a disc herniation, or is may affect highly sensitive nerve fibers in the annulus to be affected. Back pain due to nerves of the annulus becoming affected by degenerative disc changes is known as discogenic pain.