Effect of 6-month high-impact step aerobics and resistance training on BMD and tibial bending strength in sedentary premenopausal women.

The rationale of this study was to examine the effectiveness of 6-month high-impact step aerobics (SA) or moderate-intensity resistance training exercise (RT) on bone mineral density (BMD) and bone bending strength in sedentary women. Results show that SA enhanced BMD in the heel, lower leg, and lumbar spine 2. INTRODUCTION: To determine the effectiveness of 6 months of high-impact step aerobics (SA) or moderate-intensity resistance training (RT) on areal bone mineral density (aBMD) and tibial bending strength in sedentary premenopausal women. METHODS: Sixty-nine women (20-35 years old) who were randomly assigned to RT (n = 22), SA (n = 26), or non-treatment control (CON, n = 21) groups completed the study. SA had a minimum of 50 high-impact landings each training session. RT had a periodized lower body resistance training program incorporating eight exercises (65-85% of 1 repetition maximum: 1-RM). Both RT and SA met 3 times weekly. aBMD was assessed using dual X-ray absorptiometry (DXA). Tibial bending strength was assessed using mechanical response tissue analysis (MRTA). Measurements at 6 months were compared to baseline using ANCOVA, adjusted for baseline measures and covariates with α = 0.05. RESULTS: Calcaneus aBMD (0.0176 vs -0.0019 or -0.0009 g/cm2 relative to RT, p < 0.004, and CON, p < 0.006, respectively), lower leg aBMD (0.0105 vs -0.0036 g/cm2, relative to RT, p = 0.02), and lumbar spine 2 (L2) aBMD (0.0082 vs -0.0157 g/cm2 relative to CON, p < 0.02) were significantly greater in the SA group after 6 months. Tibial bending strength and bone resorption biomarkers were unchanged in all three groups after 6 months. CONCLUSION: Sedentary premenopausal women engaging in 6 months of high-impact aerobic exercise improved aBMD in the calcaneus, lower leg, and L2.

-643C > T RANKL gene polymorphism is associated with osteoporosis in Tunisian postmenopausal women.

OBJECTIVES: The dynamic nature of the skeleton is achieved by a remodeling process. Receptor activator of nuclear factor kappa B (RANK) ligand (RANKL) stimulates bone resorption by activating RANK signaling. Therefore it is considered as a candidate gene regulating susceptibility to osteoporosis. In the current study, we have investigated the association between the RANKL gene -693G > C and -643 C > T polymorphisms and bone mineral density (BMD) in a population of postmenopausal Tunisian women. METHODS: Polymorphic sites in RANKL gene (rs9533155 -693G > C and rs9533156 -643 C > T polymorphisms) were determined using PCR-RFLP analysis in 566 postmenopausal Tunisian women. All statistical analysis were examined by SPSS software. RESULTS: We have detected a significant difference in lumbar spine and hip BMD for -643C > T genotypes. For -693G > C genotypes, a significant difference was detected only in hip BMD. The distribution of -643C > T genotypes and alleles between three groups (osteoporotic, osteopenic and normal women) revealed a significant association of the TT genotype with development of osteoporosis (p = 0.01; odds ratio 2.15), although for the -693G > C polymorphism, no significant results were found. CONCLUSION: We have demonstrated the association of the -643C > T polymorphism with BMD variation and osteoporosis risk in postmenopausal Tunisian women.

Does the Bone Mineral Density of the Lumbar Spine Correlate With Dual-Energy X-ray Absorptiometry T Score? A Cadaveric-Based Analysis of Computed Tomography Densitometry.

BACKGROUND: Pedicle screw loosening is a complication of spinal instrumentation in osteoporotic patients. Dual-energy x-ray absorptiometry scans are not able to detect variations in bone mineral density (BMD) within specific regions of vertebrae. The purpose of this study was to investigate whether spine T scores correlate with cortical and cancellous BMD of pedicles and other 6 anatomical regions of lumbar spine. METHODS: Eleven cadaveric spines with a mean age of 73 years were digitally isolated by applying filters for cortical and cancellous bone on computed tomography images. Eleven L5 vertebrae were separated into 7 anatomical regions of interest using 3-dimensional software modeling. Hounsfield units (HU) were determined for each region and converted to cortical and cancellous BMD with calibration phantoms of known BMD. Correlations between T scores and HU values were calculated using Pearson correlation coefficient. RESULTS: Mean vertebral T score was 0.15. Cortical BMD of pedicles was strongly correlated with T score (R 2 = 0.74). There was moderate correlation between T score and cortical BMD of lamina, inferior articular process (IAP), superior articular process (SAP), spinous process, and vertebral body. There was weak correlation between T score and cortical BMD of transverse process (R 2 = 0.16). Cancellous BMD of vertebral body was strongly correlated with T score (R 2 = 0.82). There was moderate correlation between T score and cancellous BMD of pedicles, spinous process, and transverse process. There was weak correlation between T scores and cancellous BMD of lamina, IAP, and SAP. CONCLUSIONS: There is a strong correlation between T scores and cortical BMD of lumbar pedicle. There is strong correlation between T scores and cancellous BMD of vertebral body. Cortical and cancellous BMD of transverse process and lamina were weakly correlated with T score and less affected by osteoporosis. CLINICAL RELEVANCE: Patients with osteoporosis may especially benefit from the development of extrapedicular fusion strategies due to the relatively higher bone density of these fixation sites.

Causal Effect of Serum Magnesium on Osteoporosis and Cardiometabolic Diseases.

Serum magnesium is associated with osteoporosis and cardiometabolic diseases, but their causal associations remain elusive. We used the two-sample Mendelian randomization (MR) study to explore the causal roles of serum magnesium on osteoporosis and cardiometabolic diseases by using the aggregated genome-wide association studies (GWASs). Six single-nucleotide polymorphisms (SNPs, p < 5 × 10-8) associated with serum magnesium concentrations were all used as instrumental variables. A genetic predisposition to higher serum magnesium concentrations was inversely associated with lower lumbar spine bone mineral density (BMD, beta-estimate: -1.982, 95% CI: -3.328 to -0.635, SE: 0.687, p = 0.004), which was further confirmed by multiple sensitivity analyses. There was limited evidence of associations between serum magnesium and type 2 diabetes, coronary artery disease, heart failure, and atrial fibrillation. This work provided strong evidence that genetically increased serum magnesium concentrations were causally associated with low lumbar spine BMD and suggested that serum magnesium concentrations may be crucial to prevent osteoporosis.

Impact of lumbar syndesmophyte on bone health as assessed by bone density (BMD) and bone texture (TBS) in men with axial spondyloarthritis.

INTRODUCTION: Patients with spondyloarthritis (SpA) have an elevated incidence of osteoporosis and are at increased risk of pathological vertebral fracture. Evaluation of bone density by dual energy X-ray absorptiometry (DXA) has its limits in fracture prediction, already known in this population. One hypothesis is that the presence of lumbar syndesmophyte could overestimate the spine bone mineral density (BMD). Trabecular bone score (TBS) is a new texture measurement correlated with bone microarchitecture. Previous studies have shown that TBS is mildly impacted by osteoarthritis and thus could be a predictor of fracture better than spine BMD. We aimed to evaluate a male population of SpA with BMD and TBS measurement and see the impact of lumbar syndesmophytes. METHOD: Two cohorts of SpA male patients (Lausanne, Sofia) with SpA disease, clinical and bone parameters (femoral neck and total spine BMD+spine TBS) were merged. We compared BMD and TBS results regarding to the presence/absence of syndesmophytes. RESULTS: Our study concerned 51 men [29 with lumbar syndesmophytes (L1 to L4,≥1), 22 without], fulfilling the European Spondyloarthropathy Study Group (ESSG) and the Assessment of SpondyloArthritis international Society (ASAS) criteria. Mean age was 52.18 years old (no difference between the 2 groups) and mean body mass index (BMI) 27.47kg/m2 (29.12±0.67 with and 25.30±0.81 without, P=0.0006). For the overall population mean BMD T-score at the spine was -0.55±1.54, mean BMD T-score at the femoral neck -1.20±0.95 and mean lumbar spine TBS was 1.26±0.13. Regarding to the presence or the absence of syndesmophytes, mean spine BMD T-score was -0.07±1.63 and -1.18±1.16 (P=0.009 and 0.250 before and after adjustment for BMI), mean femoral neck BMD T-score was -1.37±0.93 and -0.97±0.94 (P=0.14 and 0.03 before and after adjustment for BMI) and mean TBS was 1.21±0.12 and 1.33±0.11 (P=0.001 and 0.06 before and after adjustment for BMI) respectively for SpA men with and without syndesmophytes. CONCLUSION: Our results showed that SpA men with and without syndesmophytes have lower results compared to the normal population regarding hip BMD, spine TBS and spine BMD except for men with syndesmophytes who have a normal BMD spine T-score. These results suggest that TBS is not influenced by the syndesmophytes in opposite to spine BMD and could be measured in this population in addition to the neck BMD to assess the bone fragility.