Obesity is associated with reduced disc height in the lumbar spine but not at the lumbosacral junction.
METHODS
Cross-sectional, community-based study.


OBJECTIVE
To investigate the relationships between obesity, disc height, and low back pain in the lumbosacral spine.


BACKGROUND
Although obesity is a recognized risk factor for low back pain, our understanding of the mechanisms for this is limited. The evidence for an association between obesity and spinal structural changes is also conflicting.


METHODS
Seventy-two participants from a community-based study of musculoskeletal health underwent magnetic resonance imaging from the T12 vertebral body to the sacrum. Disc height was measured from L1-L2 to L5-S1. Body mass index was measured and low back pain in the previous 2 weeks was assessed.


RESULTS
The mean and total lumbar disc heights were reduced in obese individuals compared with nonobese individuals (mean height (standard error):1.04 (0.03) cm vs. 1.14 (0.02) cm, P = 0.01; total height (standard error):4.16 (0.11) cm vs. 4.57 (0.10) cm, P = 0.01), after adjusting for age, sex, and height. Although obesity was associated with reduced disc heights at the L1-L2 and L3-L4 levels, there were no significant relationship at the lumbosacral junction (mean difference (95% confidence interval [CI]):0.10 (-0.14 to 0.16) cm, P = 0.89). Both mean and total lumbar disc heights were negatively associated with recent pain after adjusting for age, sex, and height (mean height: mean difference (95% CI):0.09 (0.02-0.17) cm, P = 0.02; total height: mean difference (95% CI): 0.37 (0.07-0.66) cm, P = 0.02). However, these relationships were no longer significant when we also adjusted for weight (mean height; mean difference (95% CI):0.07(-0.009 to 0.15) cm, P = 0.08; total height: mean difference (95% CI):0.28 (-0.04 to 0.60) cm, P = 0.08). There were no significant relationships between disc height and recent pain at the lumbosacral junction.


CONCLUSIONS
Obesity was associated with reduced disc height in the lumbar spine, but not at the lumbosacral junction, suggesting these joints may have different risk factors. There was also evidence for an inter-relationship between obesity, lumbar disc height, and recent pain, suggesting that structural changes have a role in back pain and may in part explain the association between obesity and back pain.
*Department of Epidemiology and Preventive Medicine, School of Public Health and Preventive Medicine, Monash University, Alfred Hospital, Melbourne, Victoria, Australia †Healthcare Imaging Services, Epworth Hospital, Richmond, Victoria, Australia ‡Department of Medicine, Central Clinical School, Monash University, Alfred Centre, Melbourne, Victoria, Australia; and §Menzies Research Institute, Hobart, Tasmania, Australia.
Donna M
DM
Urquhart
Ivan
I
Kurniadi
Kevin
K
Triangto
Yuanyuan
Y
Wang
Anita E
AE
Wluka
Richard
R
OʼSullivan
Graeme
G
Jones
Flavia M
FM
Cicuttini
D000328:Adult; D000368:Aged; D016009:Chi-Square Distribution; D003430:Cross-Sectional Studies; D005260:Female; D006801:Humans; D007403:Intervertebral Disc / Q000000981:diagnostic imaging / Q000473:pathology / Q000503:physiopathology*; D017116:Low Back Pain / Q000503:physiopathology*; D008159:Lumbar Vertebrae / Q000000981:diagnostic imaging / Q000473:pathology / Q000503:physiopathology*; D008161:Lumbosacral Region; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D009765:Obesity / Q000503:physiopathology*; D011859:Radiography; D012447:Sacrum / Q000000981:diagnostic imaging / Q000473:pathology / Q000503:physiopathology*