Disc degeneration, the break down of the discs in the back, is a major cause of lower back pain in adults. When looking at an x-ray at the discs, the healthy discs have a white center (nucleus), while the annulus seems dark. The nucleus will get darker as the disc degenerates until it becomes black, which means complete degeneration. Although the actual definitions for the breakdown may vary, most researchers believe and agree that it is likely caused by fluid loss in the center, compression of the disc so it loses height, and little breaks (fissures) in the bone.
Doctors don’t understand exactly the reason what role the fissures or ruptures have in lower back pain, but they do suspect that it is when the degeneration is at the moderate level that the most pain occurs, rather than when the degeneration has become severe. The authors of this study tested this theory by studying 412 patients who were divided into three groups: those with completely normal discs (white nucleus), those with severely degenerated discs (black nucleus), and those where were in between (gray nucleus).
All the patients were 40 years old and the group was fairly equally divided between men (199) and women (213). They all completed a questionnaire regarding how much pain they experienced in the back and legs, their physical activity, leisure activities, and several demographic measures, such as income and education levels. Magnetic resonance imaging (MRI) was done on all patients to see the extent of the disc degeneration, if any.
The results of the questionnaires and tests found that patients in the no degeneration group and those with moderate degeneration both complained of about the same levels of lower back pain in the previous year, while those with severe degeneration complained of significantly more lower back pain. Statistically, the overall lower back pain was measured at 69 percent, regardless of whether there were gray discs. A significant difference was found when black discs were present though. Those patients who had no black discs measured in at about 60 percent while those with black discs were at 86 percent if they had two.
The authors wrote that their findings determined that it wasn’t the moderately degenerated discs that were causing the bulk of lower back pain from disc degeneration, but it was the severely degenerated ones that were the main cause. They point out that this is a significant finding because patients who have more than one black disc have double the risk of developing lower back pain.