Hounsfield Units Value is a Better Predictor of Bone Mineral Density Than the Vertebral Bone Quality Score of Magnetic Resonance Imaging in Patients with Lumbar Degenerative Diseases

Background: Computed tomography Hounsfield unit (HU) and magnetic resonance imaging (MRI)-based vertebral bone quality (VBQ) score are both alternative tool to the dual energy x-ray absorptiometry(DEXA) scan T-score to quantify the bone quality. However, it is not known which method more accurately reflects vertebral bone mineral density. Purpose: To evaluate the best method for evaluating vertebral bone mineral density in patients undergoing lumbar spine surgery.Methods: Eighty-five patients who had at most two vertebrae with severe degeneration at L1–L4 were retrospectively reviewed.HU value was measured by axial CT image, VBQ score was calculated by T1-weighted lumbar MRI image, and L1-L4 T-score and bone mineral density (BMD) were measured by DEXA.The correlation of the vertebral HU value and VBQ score to the T-score was analyzed.Results: There were 52 female and 33 male patients. The average age was 57.18±9.65 years . HU values had a positive correlation with BMD and T-score. The correlation coefficients between HU and T-score was 0.751(<0.001) for L1; 0.699(<0.001) for L2; 0.618(<0.001) for L3; 0.543(<0.001) for L4; and 0.677(<0.001) for L1-4.However,VBQ score had a negative correlation with BMD and T-score. The correlation coefficients between VBQ score and T-score was -0.231(<0.05) for L1; -0.246(<0.05) for L2; -0.268(<0.05) for L3; -0.252(<0.05) for L4; and -0.346(<0.01) for L1-4. The correlation coefficients of HU value at L1–L4 were higher than the correlation coefficients of VBQ score . Conclusions: HU value was a better predictor of vertebral bone mineral density than VBQ score in patients with lumbar degenerative disease.

Exercise Modality Affects Older Adult CT-Derived Muscle and Bone Loss During Caloric Restriction

Caloric restriction (CR) can exacerbate muscle and bone loss. We examined 18-month changes in computed tomography (CT)-derived trunk muscle, and volumetric bone mineral density (vBMD) and finite element-estimated bone strength of the spine and hip in 55 older adults randomized to CR alone or CR plus aerobic (CR+AT) or resistance (CR+RT) training. Trunk muscle area loss trended higher with CR+AT [-16.8 cm2 (95% CI: -26.4,-7.1) vs CR: -6.7 (-12.8,-0.5), CR+RT: -9.0 (-14.5,-3.4)]. Spine vBMD loss trended higher with CR+AT [−0.014 g/cm3 (−0.027,−0.001) vs. CR: −0.005 (−0.022,0.012), CR+RT: −0.004 (−0.019,0.011)], and similarly for vertebral bone strength. Hip vBMD losses trended lower with CR+RT [−0.015 g/cm3 (−0.024,−0.006) vs. CR: −0.027 (−0.036,−0.019), CR+AT: −0.029 (−0.037,−0.020)]. Hip vBMD and trunk muscle losses were positively correlated (r=0.53), and spine vBMD loss tended to increase with trunk muscle loss (r=0.21) and fat infiltration (r=0.17). Collectively, aerobic training was less effective at preserving muscle-bone health during CR.

Abcc6 null mice a model for mineralization disorder PXE show vertebral osteopenia without enhanced intervertebral disc calcification with aging

Chronic low back pain is a highly prevalent health condition intricately linked to intervertebral disc degeneration. One of the prominent features of disc degeneration that is commonly observed with aging is dystrophic calcification. ATP-binding cassette sub-family C member 6 (ABCC6), a presumed ATP efflux transporter, is a key regulator of systemic levels of the mineralization inhibitor pyrophosphate (PPi). Mutations in ABCC6 result in pseudoxanthoma elasticum (PXE), a progressive human metabolic disorder characterized by mineralization of the skin and elastic tissues. The implications of ABCC6 loss-of-function on pathological mineralization of structures in the spine, however, are unknown. Using the ABCC6 -/- mouse model of PXE, we investigated age-dependent changes in the vertebral bone and intervertebral disc. ABCC6 -/- mice exhibited diminished trabecular bone quality parameters at 7-months which remained significantly lower than the wild-type mice at 18 months-of-age. ABCC6 -/- vertebrae showed increased TRAP staining along with decreased TNAP staining, suggesting an enhanced bone resorption as well as decreased bone formation. Surprisingly, however, loss of ABCC6 resulted only in a mild, aging disc phenotype without evidence of dystrophic mineralization. Finally, we tested the utility of oral K3Citrate to treat the vertebral phenotype since it is shown to regulate hydroxyapatite mechanical behavior. The treatment resulted in inhibition of osteoclastic response and an early improvement in mechanical properties of the bone underscoring the promise of potassium citrate as a therapeutic agent. Our data suggest that although ectopic mineralization is tightly regulated in the disc, loss of ABCC6 compromises vertebral bone quality and dysregulates osteoblast-osteoclast coupling.

The contributions of cartilage endplate composition and vertebral bone marrow fat to intervertebral disc degeneration in patients with chronic low back pain

Purpose: The composition of the subchondral bone marrow and cartilage endplate (CEP) could affect intervertebral disc health by influencing vertebral perfusion and nutrient diffusion. However, the relative contributions of these factors to disc degeneration in patients with chronic low back pain (cLBP) have not been quantified. The goal of this study was to use compositional biomarkers derived from quantitative MRI to establish how CEP composition (surrogate for permeability) and vertebral bone marrow fat fraction (BMFF, surrogate for perfusion) relate to disc degeneration. Methods: MRI data from 60 patients with cLBP were included in this prospective observational study (28 female, 32 male; age = 40.0 ± 11.9 years, 19–65 [mean ± SD, min–max]). Ultra-short echo-time MRI was used to calculate CEP T2* relaxation times (reflecting biochemical composition), water-fat MRI was used to calculate vertebral BMFF, and T1ρ MRI was used to calculate T1ρ relaxation times in the nucleus pulposus (NP T1ρ, reflecting proteoglycan content and degenerative grade). Univariate linear regression was used to assess the independent effects of CEP T2* and vertebral BMFF on NP T1ρ. Mixed effects multivariable linear regression accounting for age, sex, and BMI was used to assess the combined relationship between variables. Results: CEP T2* and vertebral BMFF were independently associated with NP T1ρ (p = 0.003 and 0.0001, respectively). After adjusting for age, sex, and BMI, NP T1ρ remained significantly associated with CEP T2* (p = 0.0001) but not vertebral BMFF (p = 0.43). Conclusion: Poor CEP composition may play a significant role in disc degeneration severity and can affect disc health both with and without deficits in vertebral perfusion.

Development and characterization of a novel human 3D model of bone metastasis from breast carcinoma in vitro cultured

Breast cancer frequently metastasizes to the skeleton causing significant morbidity. Here, we set-up a novel and advanced ex vivo model by using fresh tissue from human vertebral bone metastasis from breast carcinoma patients able to retain the tumor microenvironment and tumor cells heterogeneity.