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.
Watch: Video: What Is a Degenerative Disc and the Degenerative Cascade?
Unlike muscles, which have good blood supply, once a spinal disc is injured it cannot repair itself.
Stages of Degenerative Disc Disease
In the 1970s, 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), the studies also concluded that this process happened over a period of 20 to 30 years.
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Although patients over 60 may have pain from other degenerative conditions, such as degenerative osteoarthritis and/or spinal stenosis, it is uncommon for them to have pain from degenerative disc disease or other disc problems.
While this summary is a simplification of Kirkaldy-Willis's 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.