Association Between Bone Mineral Density And Lumbar Disc Degeneration In Women

Objectives:Lumbar Disc Degeneration (LDD) are very common conditions in the aging population which may cause severe lower back pain and decrease the quality of life. Especially in postmenopausal women, with the sharp decline in estrogen levels, bone density drops down very quickly, and also will bring a more severe lumbar disc degeneration. Over the past three decades, relationship between the BMD and LDD remains controversial. Awareness of the correlation is not uniform. Part of the clinical and epidemiological studies found that bone mineral density and degenerative spinal disc disease are negatively correlated, the underlying mechanism of which has no definitive explanation though. The aim of our research was to study the relationship between LDD and BMD of the lumbar spine.Study design:The study population consisted of 184 women (aged 30.9-81.6 years, mean 58.8 years), which contained 97 postmenopausal women (mean 66.7 years) who had health checkup for BMD and lumbar spine MRI examination from January 2015 to December 2015 at the Sir Run Run Shaw Hospital of Zhejiang University. Bone density examination was operated by specialists; dual-energy X-ray absorptiometry was used to measure the lumbar spine (L1-L4) BMD. The severity of LDD was graded from T2-weighted MRI images using the five-grade Pfirrmann classification. Four vertebral levels (L1-L4) were studied (total 736 discs). The association between lumbar BMD, T-score and Z-score and the severity of LDD was studied separately for each vertebral level with ANOVA analysis, using potential confounders (age and BMI) as covariates.Results:1. Lumbar spine BMD and T-score of women negatively correlated with age (r EMD =-0.632, r T=-0.632, p<0.01), and positively correlated with BMI (r BMD=0.226, r T= 0.225, p<0.01) in women;2. Elder women had more severe Lumbar disc degeneration (mildly, moderately and severely degenerative women had average ages of 49.6 ± 9.5 years,61.3 ± 8.5 years and 66.0 ± 7.2 years respectively) and BMI may aggravate Lumbar disc degeneration (the average BMI of mildly, moderately and severely degenerative women were 23.0 ± 2.2 kg/m2,23.4 ± 3.3 kg/m2 and 23.7 ± 3.3 kg/m2 respectively);3. Higher lumbar BMD and Z-score were associated with more severe LDD in postmenopausal women at all studied levels (L1-L4), Pearson correlation coefficient ranging from 0.352 to 0.530. Statistical significance of any result did not alter after controlling for confounding factors.Conclusions:1、Lumbar spine BMD and T-score of women negatively correlated with age and positively correlated with BMI.2、Lumbar disc degeneration positively correlated with age and BMI.3、Higher lumbar BMD/Z-score were associated with more severe LDD in postmenopausal women.