There is minimal blood supply to the disc, and blood is what brings healing nutrients and oxygen to damaged structures in the body. This means that the spinal disc lacks any significant reparative powers. Unlike muscles, which have good blood supply, once a spinal disc is injured it cannot repair itself.
Stages of Degenerative Disc Disease
In the 1970's, Kirkaldy-Willis first described the "degenerative cascade" of degenerative disc disease. He postulated that after an individual suffers a torsional (twisting) injury to the disc, the disc would degenerate in three general stages.
- First, there is significant dysfunction caused by the acute back pain of the injury.
- Next, there is a long phase of relative instability at that particular vertebral segment and the patient will be prone to intermittent bouts of back pain.
- Finally, the body re-stabilizes the segment and the patient experiences fewer episodes of back pain.
Based on the observation that demographic studies show less back pain from degenerative disc disease in elderly adults (over 60 years) than in younger adults (30 to 50 year-olds), he also concluded that this process happened over a period of 20 to 30 years. Although elderly patients may have pain from facet osteoarthritis, it is uncommon for them to have disc problems.
While this summary is a simplification of Kirkaldy-Willis' extensive work, it lays the framework for what is known today. We do know that lumbar disc degeneration is a very common and natural process, and only in limited cases does it become painful.
In This Article:
The "Degenerative Cascade" of a Degenerating Disc
Degenerative Disc Disease and Low Back Pain
The natural history of lumbar degenerative disc disease is relatively benign. The pain tends to be intermittent, and although at times the pain may seem to be getting worse, the painful symptoms are generally not progressive. While the disc degeneration will progress, the low back pain and other symptoms do not tend to get worse with the progression of the degeneration.
Many patients worry that if they are have a lot of low back pain when they are only 35 years old, the pain will become much worse and they may be in a wheelchair by the time they're in their sixties. However, if patients can find a way to manage their back pain and maintain their function, the natural history is really quite favorable. With continued disc degeneration, all the inflammatory proteins within the disc space will eventually burn out, and the disc will usually become stiffer, thus decreasing micro-motion. In fact, someone who is 65 years old is actually less likely to have discogenic back pain than someone who is 35 years old.