The Clinic Study Of DXA Femoral Neck Strength Analysis

Objective To estimate dual energy X-ray absorptiometry(DXA) short-term variability of hip strength analysis (HSA) in femoral necks and body composition parameters and establish the least significant change (LSC) to monitor these parameters from repeat subject scans.Methods73health volunteers had two repeated DXA measurements of bilateral proximal femur and50health volunteers had two repeated DXA measurements of whole body. Short-term variability of HSA parameters and whole body composition parameters were expressed as the root-mean-square coefficient (RMS-CV%) of variation and LSC at95%confidence level.Results At the single hip, the HSA parameters RMS-CV%were observed in0.8～4.0%of cases. At the dual hips, the HSA parameters RMS-CV%were0.6～2.8%。 The HSA parameters reproducibility improved13～33%by measuring the dual femur.Conclusions DXA measurements have low precision errors level in HSA and whole body composition scanning. Objective After exanimate the difference in hip strength analysis (HSA) parameters which included bone cross-sectional area (CSA), cross-sectional moment of inertia (CSMI), section modulus (Z), Periosteal Diameter (PD), Endocortical Diameter(ED) and Cortical Thickness (CT) at bilateral femoral neck dual energy X-ray absorptiometry (DXA) measurements, the study try to investigate the bone strength and cross section structure changes with age between men and women femoral neck by DXA scanning, and try to explain these findings by Mechanobiology theory.Methods400subjects were selected to compare the HSA parameters in dual femora necks. The data from3855normal subjects were analyzed to investigate HSA parameters in different sex group and age group. The study also investigated the difference of HSA parameters in normal, osteopenia and osteoporosis group. Age trends of HSA parameters (CSA, CSMI and Z) were evaluated in old men and postmenopausal women.Results There were high positive correlations between the left and right femoral neck HSA parameters (r=0.801～0.921, p<0.05), and there was no difference between bilateral femoral neck parameters (p>0.05). The decline of bone strength (CSA, CSMI and Z) with aging occurs in old men and postmenopausal women (r=-0.183～-0.495,p<0.05). Comparing with premenopausal women, postemenopausal women have lower bone strength and cortical thickness. Comparing with young men, old men have lower bone strength and cortical thickness, but have high periosteal diameter and endocortical diameter (p<0.05). Hip strength parameters were declined with osteoporotic fracture risk increasing (p<0.05). There were some differences between BMD and HSA parameters (CSA, CSMI and Z) in relative age trends at femoral neck (p<0.05)Conclusions There was no difference between left and right femoral neck bone strength. Aging loss of bone mass in the femoral neck does not necessarily mean reduced bone strength directly. HSA parameters in old men and postmenopausal women showed that reduction in bone strength was not dependent on decline in BMD. Objective The aim of this dual energy X-ray absorptiometry (DXA) study was to compare hip strength analysis (HSA) at femoral neck in low weight, overweight or obesity adults with gender matched normal weight controls. The relationship of body weight, lean mass (LM) and fat mass (FM) was investigated to indices of femoral neck strength.Methods3855adults were separated by body mass index (BMI) into low weight, normal weight, overweight and obesity groups. DXA measurements of the proximal femur and total body were made in these adults groups using a DXA bone densitometer. Bone mineral density (BMD), LM, FM, and HSA parameters which included bone cross-sectional area (CSA), cross-sectional moment of inertia (CSMI) and the section modulus (Z) were measured. Data were analyzed by Student’s t-test, Pearson correlation coefficients examination, and one-way analysis of covariance (ANCOVA).Results Overweight and obesity adults had higher body weight, LM, FM, BMI, CSA, CSMI and Z than normal weight controls, but low weight adults had lower body weight, LM, FM, BMI and HSA parameters than normal weight controls (p<0.05) LM correlated well with CSA, CSMI and Z in all BMI groups (r=0.310～0.616, p<0.05). After adjustment for LM, there were no significant differences between normal weight group with low weight, overweight or obesity groups. However, the differences remain significant after adjustment for FM between normal weight group with low weight, overweight and obesity groups (p<0.05). After adjustment for weight, the differences remain significant between normal weight group with low weight, overweight and obesity groups in women (p<0.05) but not in men.Conclusions This study supports the conclusion that overweight individuals have greater hip neck strength in comparison with normal weight controls, and femoral neck bone strength is adapted with "active stress" provided by muscle. Lean mass is a major determinant for femoral neck strength in all subjects.