This study aims to investigate the regional variations of trabecular morphological parameters and mechanical parameters of the femoral head,as well as to determine the relationship between trabecular morphological and mechanical parameters.Seven femoral heads from patients with fractured proximal femur were scanned using a micro-CT system.Each femoral head was divided into 12 sub-regions according to the trabecular orientation.One 125 mm^3 trabecular cubic model was reconstructed from each sub-region.A total of 81 trabecular models were reconstructed,except three destroyed sub-regions from two femoral heads during the surgery.Trabecular morphological parameters,i.e.trabecular separation(Tb.Sp),trabecular thickness(Tb.Th),specific bone surface(BS/B V),bone volume fraction(BV/TV),structural model index(SMI),and degree of anisotropy(DA) were measured.Micro-finite element analyses were performed for each cube to obtain the apparent Young's modulus and tissue level von Mises stress distribution under 1%compressive strain along three orthogonal directions,respectively.Results revealed significant regional variations in the morphological parameters(P<0.05).Young's moduli along the trabecular orientation were significantly higher than those along the other two directions.In general,trabecular mechanical properties in the medial region were lower than those in the lateral region.Trabecular mechanical parameters along the trabecular orientation were significantly correlated with BS/BV,BV/TV,Tb.Th,and DA.In this study,regional variations of microstructural features and mechanical properties in the femoral head of patients with proximal femur fracture were thoroughly investigated at the tissue level.The results of this study will help to elucidate the mechanism of femoral head fracture for reducing fracture risk and developing treatment strategies for the elderly.
Linwei LüGuangwei MengHe GongDong ZhuJiazi GaoYubo Fan
Objective To assess the effects of high-frequency loading using whole body vibration on distal radius density in adults. Methods The volunteers diagnosed with osteoporosis or osteopenia in the First Hospital of Jilin University from January 2011 to December 2014 were recruited. All the subjects performed foot-based, whole body vibrations on the vibration platform(35 Hz, 0.25 g) once a day, for 15 minutes per session over a period of 4 weeks. The bone mineral density of distal radius(rB MD) was measured using dual-energy X-ray absorptiometry at before, 2-week, and 4-week after the vibration treatment. Blood pressures were measured at the end of the vibration treatment. Results A total of 114 volunteers were enrolled. The average rB MD before the treatment was 0.331±0.014 g/cm^2. It was reached 0.337±0.019 g/cm2 at the end of the fourth week, increased by 1.79%(P<0.05). Whole body vibration increased rB MD of men and women respectively(1.77% and 1.80%, P<0.05). Blood pressures did not change in any of the groups. Conclusion A 4-week whole body vibration was feasible and contributed to increase of rBMD.
