Study design: A prospective follow-up study.
Objective: The aim of this study was to investigate whether early lumbar disc degeneration (DD) in young low back pain (LBP) patients predicts progression of degenerative changes, pain, or disability in a 30-year follow-up.
Summary of background data: MRI is an accurate method for studying degenerative changes in intervertebral discs. Decreased signal intensity (SI) can be used as indication of decreased water content. Long-term prognosis of early DD remains unclear.
Methods: In an earlier study, 75 conscripts aged 20 years with LBP had their lumbar spine examined by MRI. At a follow-up of 30 years, the subjects were contacted; 35 of 69 filled a pain and disability questionnaire, and 26 of 35 were also reexamined clinically and by MRI. The images were evaluated for decreased SI and other degenerative changes. Association between decreased SI of a disc at baseline and the presence of more severe degenerative changes in the same disc space at follow-up was analyzed using Fisher exact test. Association between decreased baseline SI and pain/disability scores from the questionnaire was analyzed with Kruskal-Wallis H test.
Results: The total number of lumbar discs with decreased SI increased from 23 of 130 (18%) to 92 of 130 (71%)-from 0.9 to 3.5 per subject during the follow-up. Distribution of DD changed from being mostly in L4-L5 and L5-S1 discs to being almost even between the four lowermost discs. Discs that had even slightly decreased SI at baseline were more likely to have severely decreased SI at follow-up, compared to healthy discs (57% vs. 11%, P < 0.001). Other degenerative changes were also more common in these discs. Severity of DD at baseline did not have a significant association with current pain or disability.
Conclusion: In young LBP patients, early degeneration in lumbar discs predicts progressive degenerative changes in the respective discs, but not pain, disability, or clinical symptoms.
Level of evidence: 4.