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The Relationship of Lumbar Multifidus Muscle Morphology to Previous, Current, and Future Low Back Pain: A 9-Year Population-Based Prospective Cohort Study

Hebert, Jeffrey J. DC, PhD*; Kjaer, Per PT, PhD*,†; Fritz, Julie M. PT, PhD; Walker, Bruce F. DC, DrPH§

doi: 10.1097/BRS.0000000000000424
Epidemiology

Study Design. Population based prospective cohort study.

Objective. We explored the cross-sectional relationships between lumbar multifidus (LM) intramuscular adipose tissue (IMAT) infiltration and low back pain (LBP) at 3 successive time points and investigated the role of IMAT in predicting the occurrence of LBP after 5 and 9 years.

Summary of Background Data. Although LBP is a major source of disease burden, the biological determinants of LBP are poorly understood.

Methods. Participants were 40-year-old adults randomly sampled from a Danish population and followed up at 45 and 49 years of age. At each time point, participants underwent magnetic resonance imaging and reported ever having had LBP, LBP in the previous year, nontrivial LBP in the previous year, or a history of pain radiating into the legs. Pixel intensity and frequencies from T1-weighted magnetic resonance images identified the greatest proportion of LM IMAT at the L4 and L5 spinal levels. IMAT infiltration was categorized as normal/mild, moderate, or severe based on tertile divisions. Associations were explored with crude and adjusted odds ratios (aORs) from logistic regression models. Model covariates included sex, body mass index, and occupational and leisure time physical activity.

Results. A total of 401 participants were enrolled, with 331 (83%) and 286 (71%) participants followed up at 5 and 9 years, respectively. The cross-sectional analyses demonstrated that at the age of 40 years, participants with severe IMAT infiltration demonstrated increased odds of ever experiencing LBP (aOR [95% confidence interval, 95% CI] = 3.16 [1.45–6.89]), nontrivial LBP (aOR [95% CI] = 2.82 [1.36–5.81]), LBP in the past year (aOR [95% CI] = 1.95 [1.07–3.53]), and leg pain (aOR [95% CI] = 2.08 [1.19–3.62]). There were no consistent cross-sectional associations between LBP/leg pain and LM IMAT at 45 or 49 years of age and LM IMAT did not predict future LBP or leg pain.

Conclusion. The relationship between LM IMAT and LBP/leg pain is inconsistent and may be modified by age.

Level of Evidence: N/A

Lumbar multifidus fat infiltration has been previously associated with low back pain. Our results indicate that lumbar multifidus fat infiltration is associated with low back pain at the age of 40 years, but not at 45 or 49 years of age. The association between lumbar multifidus fat infiltration and low back pain may be modified by age.

*Murdoch University School of Psychology and Exercise Science, Murdoch, Western Australia, Australia

Department of Sports Science and Clinical Biomechanics, University of Southern Denmark, Odense, Denmark and Spine Centre of Southern Denmark, Middelfart, Denmark

Department of Physical Therapy, University of Utah, and Intermountain Healthcare, Salt Lake City, UT; and

§Murdoch University School of Health Professions, Murdoch, Western Australia, Australia.

Address correspondence and reprint requests to Jeffrey J. Hebert, DC, PhD, Murdoch University School of Psychology and Exercise Science, 90 South St, ECL SS 2.015, Murdoch, Western Australia 6150; E-mail: J.Hebert@Murdoch.edu.au

Acknowledgment date: November 19, 2013. First revision date: March 22, 2014. Acceptance date: April 22, 2014.

The manuscript submitted does not contain information about medical device(s)/drug(s).

Industrial Insurance Company (now Topdanmark), the Chiropractic and Osteopathic College of Australasia and Murdoch University funds were received to support this work.

Relevant financial activities outside the submitted work: board membership, employment, payment for lectures, consultancy, grants/grants pending, payment for manuscript preparation and travel/accommodations/meeting expenses.

© 2014 by Lippincott Williams & Wilkins