BMD reduced in men with chronic low back pain
MedWire News: Men with chronic low back pain have below-average bone mineral density (BMD) at the lumbar spine, study findings show.
The research offers new insights into the mechanisms and clinical significance of back pain, say Andrew Briggs (Curtin University, Perth, Western Australia) and co-authors writing in BMC Musculoskeletal Disorders.
Briggs's team hypothesized that chronic low back pain impacts vertebral bone health and investigated this in a sample of community dwelling, middle-aged adults who were participating in the Joondalup Spinal Health Study.
The cohort comprised 29 adults with chronic low back pain and 42 adults with no history of back pain in the preceding year. In the former group, the mean duration of back pain was 13.3 years in men and 11.6 years in women, while the mean Oswestry Disability Index score was 16.2% in men and 15.4% in women.
People with and without back pain were similar with regard to baseline demographic, anthropometric, and clinical characteristics, Briggs et al note.
However, two BMD measures, assessed using dual-energy X-ray absorptiometry (DXA) at the lumbar spine, were significantly lower at L3 in men with chronic low back pain than in pain-free men.
Specifically, areal BMD was 0.09 g/cm3 lower and lateral-projection apparent volumetric BMD was 0.02 g/cm3 lower in the back pain group than in others. These differences are likely to be clinically significant, say the authors, and confer an increased susceptibility to fracture.
Using multiple linear regression models, Briggs's team then estimated that chronic low back pain, together with age, weight, and height, accounted for just over half of the variance in areal and lateral-projection apparent volumetric BMD at the L3 joint.
Noting that areal BMD is an accepted surrogate for bone strength and that lateral-projection apparent volumetric BMD reduces confounding associated with spinal degenerative disease, the authors conclude: "These findings raise important questions regarding the mechanisms related to, and clinical impact of, this association and underline the potential clinical utility of lateral-projection DXA methods to assess vertebral bone parameters."
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By Joanna Lyford