Calcified tissue international
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Calcif. Tissue Int. · Apr 2012
Intrinsic material properties of trabecular bone by nanoindentation testing of biopsies taken from healthy women before and after menopause.
Postmenopausal osteoporosis in women is characterized by an increase in bone fragility and risk of fracture. In addition to transmenopausal decline in three-dimensional trabecular bone architecture, changes in intrinsic material properties (local stiffness, damping, and hardness) may contribute to increased bone fragility. In this study, nanoindentation was used to quantify transmenopausal changes in the intrinsic properties of trabecular bone. ⋯ Elastic and viscoelastic material properties of the trabecular bone were measured using quasi-static and dynamic nanoindentation techniques, respectively. Paired Student's t tests (n = 15) were performed to assess the significance of the measured intrinsic properties. Trabecular bone microarchitecture is compromised in postmenopausal women, and although this loss is associated with a trend toward reduction in some intrinsic properties (storage modulus), we found no statistically significant changes in bone intrinsic properties between healthy pre- and postmenopausal biopsies in the quasi-static results and frequency-averaged dynamic results.
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Calcif. Tissue Int. · Mar 2012
Effect of dosing interval duration of intermittent ibandronate treatment on the healing process of femoral osteotomy in a rat fracture model.
The effects of bisphosphonate treatment schedule on fracture healing have not previously been tested. We evaluated the effect of ibandronate dosing interval duration on healing following surgical "fracture" (osteotomy) using a rat femoral fracture model. Six-week-old rats (n = 160) underwent osteotomy and were then allocated into vehicle control (CNT) or an ibandronate treatment group: 5 μg/kg daily (DAY, 5 days/week), 75 μg/kg once every 3 weeks (I-3), 150 μg/kg once every 6 weeks (I-6), resulting in the same total ibandronate dose over the study. ⋯ The structural properties of osteotomized femora were increased in the DAY group compared with CNT, but intrinsic material properties reduced inversely and became closer to those of CNT in response to increased dosing interval. Ibandronate induced formation of large calluses around osteotomies but delayed woven bone remodeling into lamellar bone and reduced intrinsic material properties in a rat fracture model. Extending the dosing interval of intermittent ibandronate treatment appeared to reduce the suppression of callus remodeling caused by ibandronate, which would have delayed healing after osteotomy.
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Calcif. Tissue Int. · Jan 2012
The risk of a second hip fracture in patients after their first hip fracture.
We investigated the incidence of additional fractures and the rate of prescription of osteoporotic pharmacotherapy after an initial hip fracture. We surveyed female patients aged 65 and over who sustained their first hip fracture between January 1, 2006, and December 31, 2007, treated at 25 hospitals in five geographic areas in Japan. Data for 1 year after the first hip fracture were collected from medical records, and questionnaires were mailed to all patients. ⋯ In comparison to the general population, women ≥65 years of age who sustained an initial hip fracture were four times as likely to sustain an additional hip fracture. Antiosteoporosis pharmacotherapy was prescribed for 436 patients (18.7%), while 1,240 patients (53.3%) did not receive any treatment during the 1-year period. Patients who have sustained one hip fracture have a higher risk of a second hip fracture compared to the general population, and most of these women receive no pharmaceutical treatment for osteoporosis.
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Calcif. Tissue Int. · Oct 2011
The combination of structural parameters and areal bone mineral density improves relation to proximal femur strength: an in vitro study with high-resolution peripheral quantitative computed tomography.
The aim of this study was to assess structural indices from high-resolution peripheral quantitative computed tomography (HR-pQCT) images of the human proximal femur along with areal bone mineral density (aBMD) and compare the relationship of these parameters to bone strength in vitro. Thirty-one human proximal femur specimens (8 men and 23 women, median age 74 years, range 50-89) were examined with HR-pQCT at four regions of interest (femoral head, neck, major and minor trochanter) with 82 μm and in a subgroup (n = 17) with 41 μm resolution. Separate analyses of cortical and trabecular geometry, volumetric BMD (vBMD), and microarchitectural parameters were obtained. ⋯ No differences in these correlations were found using 41 μm compared to 82 μm resolution. In multiple regression analysis of MCS, a combined model (age- and sex-adjusted) with aBMD and structural parameters significantly increased R (2) values (up to 0.90) compared to a model holding aBMD alone (R (2) up to 0.78) (P < 0.05). Structural parameters and aBMD are equally related to MCS, and both cortical and trabecular structural parameters obtained from HR-pQCT images hold information on bone strength complementary to that of aBMD.
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Calcif. Tissue Int. · May 2011
Role of parathyroid hormone in bone fragility of postmenopausal women with vitamin D insufficiency.
Vitamin D insufficiency is related to an increase in PTH, which might be critical for an increase in bone fragility. However, the role of endogenous PTH in vitamin D insufficiency-induced fracture risk remains unclear. The present study was performed to examine the relationships among vitamin D insufficiency, bone fragility, and PTH in 202 Japanese postmenopausal women. ⋯ The proportion of subjects with prevalent fractures was significantly higher in the group with lower PTH and lower 25(OH)D than in the group with lower PTH and higher 25(OH)D or higher PTH and higher 25(OH)D. In conclusion, vitamin D insufficiency was found to be related to prevalent fracture risk independently of PTH. Functional hypoparathyroidism, rather than functional hyperparathyroidism, might be a risk factor for bone fragility in vitamin D insufficiency.