Bone mass measurements

Ageing Effects on 3-Dimensional Femoral Neck Cross-Sectional Asymmetry: Implications for Age-Related Bone Fragility in Falling

This paper explores the effects of aging on femoral neck (FN) anatomy in a study of women aged 20-90years in relation to implications for FN fracture propensity in buckling. Five hundred and four participants were scanned by Quantitative Computed Tomography and analyzed using Quantitative Computed Tomography Pro BIT (Mindways). FN cross-section was split through geometric center into superior and inferior sectors. Bone mass, structural measurements, and bone mineral density were analyzed. Buckling ratio was calculated as ratio of buckling radius to cortical thickness. Between 2nd decade and 8th decade, age-related integral bone mass reduction in superior sector was substantially larger than in inferior sector (33% compared to 21%), especially in cortical bone superiorly compared to inferiorly (53% vs 21%; p < 0.001), principally due to reduction in cortical thickness, averaged cortical thickness (56%) with little difference in density. Superior and inferior sector trabecular bone mineral density reduction was similar at 41% and 43% respectively. Differential cortical bone loss in superior sector resulted in a 59% inferior displacement (δ) of center-of-mass from geometric center. Differences in δ and averaged cortical thickness with age accounted for a 151% increase in mean superior buckling ratio from 9 to 23. Analysis confirms significant progressive age-related superior cortical bone loss as the major age effect on FN structure with relative preservation of inferior cortex probably related to maintenance of inferior sector by regular loading as a result of standing and walking. Computation of buckling ratio may allow prediction of fracture propensity in a sideways fall.

Correlation between a bone resorption marker and structural geometry of the proximal femur in osteoporotic women treated with raloxifene

PURPOSE

To assess correlations between a bone resorption marker and the structural geometry of the proximal femur in raloxifene-treated postmenopausal women with osteoporosis.

METHODS

45 postmenopausal, osteoporotic women aged 57 to 79 (mean, 67) years underwent raloxifene treatment (60 mg/day) for 12 months. Serum type-I collagen crosslinked N-telopeptide (sNTX) as the bone resorption marker was measured at baseline and 6 months, whereas hip structure analysis (HSA) parameters of the femur (neck, intertrochanter, and shaft) were measured at baseline and 12 months using dual energy X-ray absorptiometry. The HSA parameters included areal bone mineral density (BMD), inner diameter, mean cortical thickness, cross-sectional area, section modulus, and buckling ratio. Correlations between sNTX and HSA parameters were analysed using Pearson's R.

RESULTS

At baseline, sNTX correlated inversely with BMD, cross-sectional area, mean cortical thickness, and section modulus, and positively with buckling ratio in the intertrochanter and shaft (but not the neck). These correlations were significant both crude and adjusted for age. After 12 months of raloxifene treatment, HSA parameters improved significantly for the intertrochanter and shaft only. Of the 3 femoral sites, only the change in sNTX at month 6 correlated positively with changes in the inner diameter at the intertrochanter at month 12 (r=0.303, p=0.045 adjusted for age). Changes in sNTX did not correlate with changes in any other parameters.

CONCLUSION

The surrogate markers for hip fracture including sNTX, BMD, and HSA parameters correlated significantly with each other. Improvement (decrease) of sNTX indicated reduction in bone resorption.

Hip structure analysis of bisphosphonate-treated Japanese postmenopausal women with osteoporosis

The purpose of this study was to clarify the effects of a 1-year treatment with either alendronate or risedronate on the proximal femoral geometry among Japanese women with osteoporosis by hip structure analysis. Postmenopausal women who had taken at least 90% of their prescription for alendronate (35 mg/week, 94 patients) or risedronate (17.5 mg/week, 181 patients) for 1 year were retrospectively analyzed. In the alendronate treatment group, bone mineral density (BMD), cross-sectional area (CSA), section modulus and average cortex significantly increased by 0.81, 1.35, 2.23 and 0.97% at the narrow neck and increased by 2.19, 2.28, 2.85 and 1.11% at the intertrochanteric, respectively. Buckling ratio at the intertrochanteric significantly decreased by 2.50%. The CSA, section modulus and average cortex at the shaft significantly increased at 1 year. In the risedronate treatment group, the CSA, section modulus and average cortex at the narrow neck significantly increased by 0.80, 0.95 and 0.89%, respectively. BMD, CSA, section modulus, and average cortex at the intertrochanteric significantly increased by 1.61, 0.88, 2.05 and 0.79%, respectively, and buckling ratio significantly decreased by 1.53%. BMD, CSA, section modulus, and average cortex at the shaft significantly increased. The percent change of section modulus was significantly correlated with that of BMD, CSA and average cortex and negatively correlated with that of buckling ratio at all regions in both treatment groups. Statistically significant differences between the alendronate and risedronate groups were seen for section modulus in the narrow neck and CSA in the intertrochanteric. In conclusion, Japanese osteoporotic women treated by either alendronate or risedronate showed significant improvements of geometry in proximal femur within 1 year.

Effects of raloxifene treatment on the structural geometry of the proximal femur in Japanese women with osteoporosis

The purpose of this study was to clarify the effects of 2-year treatment with raloxifene on the proximal femoral geometry among Japanese patients with osteoporosis by hip structure analysis. One hundred ninety-eight community-dwelling postmenopausal women with osteoporosis were enrolled. The structural variables were areal bone mineral density (BMD), cross-sectional area (CSA), section modulus (index of resistance to bending forces), and buckling ratio (index of cortical instability). BMD, CSA, and section modulus at the narrow neck significantly increased by 1.27, 2.67, and 3.90% at 2 years, respectively. BMD, CSA, and section modulus at the intertrochanter significantly increased by 2.55, 4.49, and 6.60% at study termination, respectively. The buckling ratio at the intertrochanter decreased by 2.36% at 1 year, but differences at 2 years became non-significant. Parameters at the shaft were qualitatively similar to those of the narrow neck and intertrochanter. The percent change of the section modulus was significantly higher than that of BMD at 2 years in all three regions. The percent changes of the section modulus is strongly correlated with the percent changes of BMD and CSA, and negative correlated with the percent changes of buckling ratio in all regions. In conclusion, Japanese osteoporotic women on raloxifene therapy have significant improvements of both BMD and geometry in the proximal femur.

Structural trends in the aging proximal femur in Japanese postmenopausal women

Hip structure analysis (HSA) can be used to measure proximal femur geometry using conventional DXA scans of the hip. This study is the first analysis of HSA data in Japanese women to evaluate apparent age trends in the geometry of cross-sectional regions in the proximal femur. 409 Japanese women aged from 50 to 93 years of age were measured by DXA at three sites (narrow neck, intertrochanter, shaft). Using the mean value those between 50-59 years as a reference value, age trends were evaluated using groupings of 5-year intervals and those over 80 as a single group. BMD at three measured sites and section modulus (index of bending strength) at narrow neck declined in a similar age dependent manner, but section modulus at intertrochanter and shaft showed a different pattern. The decline in section modulus at narrow neck occurs after 50-59 years of age, whereas section modulus at intertrochanter remain 70-74 years, after that began to decrease. Section modulus at shaft, an uncommon fracture location, remains fairly static through life. In conclusion, HSA in Japanese women showed that reduction in geometric strength, as reflected by the section modulus, was not dependent on decline in BMD.

In vivo short-term precision of hip structure analysis variables in comparison with bone mineral density using paired dual-energy X-ray absorptiometry scans from multi-center clinical trials

Hip structural analysis (HSA) is a technique for extracting strength-related structural dimensions of bone cross-sections from two-dimensional hip scan images acquired by dual energy X-ray absorptiometry (DXA) scanners. Heretofore the precision of the method has not been thoroughly tested in the clinical setting. Using paired scans from two large clinical trials involving a range of different DXA machines, this study reports the first precision analysis of HSA variables, in comparison with that of conventional bone mineral density (BMD) on the same scans. A key HSA variable, section modulus (Z), biomechanically indicative of bone strength during bending, had a short-term precision percentage coefficient of variation (CV%) in the femoral neck of 3.4-10.1%, depending on the manufacturer or model of the DXA equipment. Cross-sectional area (CSA), a determinant of bone strength during axial loading and closely aligned with conventional DXA bone mineral content, had a range of CV% from 2.8% to 7.9%. Poorer precision was associated with inadequate inclusion of the femoral shaft or femoral head in the DXA-scanned hip region. Precision of HSA-derived BMD varied between 2.4% and 6.4%. Precision of DXA manufacturer-derived BMD varied between 1.9% and 3.4%, arising from the larger analysis region of interest (ROI). The precision of HSA variables was not generally dependent on magnitude, subject height, weight, or conventional femoral neck densitometric variables. The generally poorer precision of key HSA variables in comparison with conventional DXA-derived BMD highlights the critical roles played by correct limb repositioning and choice of an adequate and appropriately positioned ROI.

Rehabilitation of orthopedic and rheumatologic disorders. 1. Osteoporosis assessment, treatment, and rehabilitation

This self-directed learning module highlights a clinical vignette of a female patient with osteoporosis and addresses the clinical presentation, assessment, medical management, and rehabilitation approaches to a patient with an acute vertebral fracture. It is part of the study guide on osteoporosis in the Self-Directed Physiatric Education Program for practitioners and trainees in physical medicine and rehabilitation. This chapter emphasizes the differential diagnosis, clinical diagnostic considerations, current pharmacotherapy, invasive procedure options, and orthotic and exercise interventions for a patient with postmenopausal osteoporosis.

OVERALL ARTICLE OBJECTIVE

To summarize the clinical evaluation, medical management, and rehabilitation strategies in women with postmenopausal osteoporosis and acute vertebral fracture presentation.