Burned-out discs stop hurting: fact or fiction?
METHODS
Cross-sectional study of a general-population sample.


OBJECTIVE
The aim was to test the hypothesis that moderate disc degeneration (DD) is stronger associated with low back pain (LBP) than severe degeneration, and also to identify a possible dose-response relationship between numbers of degenerated discs and LBP.


BACKGROUND
Among many clinicians there has been a belief that DD initially causes pain because of the penetration of fluid nuclear material through annular fissures, and that pain eventually resolves as the nucleus becomes fibrotic and can no longer penetrate the fissures.


METHODS
From a population-based cohort of 412 individuals, all aged 40, three groups were created for a primary analysis: those with exclusively normal discs (white nuclei on a T2-weighted MRI), those with moderate DD (grey) + normal, and those with severely degenerated (black) + normal discs. The number of individuals reporting LBP during the past year (the most relevant for chronic/intermittent pain) and the past month were separately related to DD. Second, a possible dose-response in terms of numbers of abnormal discs was analyzed.


RESULTS
The percentage of people with LBP was virtually not influenced by grey discs, where the fraction with pain during the past year was close to 69% irrespective of the presence or number of grey discs. Black discs, however, increased the corresponding fraction from 60%, if no black discs, to 86% for those with 2 (odds ratio of 2 per number of black disc). The risk for LBP during the past year attributed to black discs was 11%.


CONCLUSIONS
The data could not support the hypothesis that severely degenerated discs are "burned out" and become less painful. People with black discs had a higher prevalence of LBP compared to those with grey or normal discs, the latter 2 being equally often painful.
Bendix
Tom
T
The Back Research Center, Funen Hospital, Ringe, Denmark. tbendix@health.sdu.dk
Kjaer
Per
P
Korsholm
Lars
L
D000328:Adult; D003430:Cross-Sectional Studies; D005260:Female; D006801:Humans; D007403:Intervertebral Disc / Q000000981:diagnostic imaging / Q000473:pathology*; D008297:Male; D010147:Pain Measurement / Q000379:methods; D011859:Radiography; D013122:Spinal Diseases / Q000000981:diagnostic imaging / Q000473:pathology*; D013997:Time Factors