BACKGROUND:The authors found that when the bilateral percutaneous vertebral augmentation is used to treat osteoporotic vertebral compression fractures with a total bone cement injection of 4 mL or more,different distribution patterns were usually presented on the X-rays;however,there were few reports addressing the effects of these patterns of bone cement distribution on the biomechanical properties of fractural vertebrae. OBJECTIVE:To further explore the biomechanical effects of different bone cement filling doses and distribution patterns on biomechanics of the fractural vertebrae using the finite element method. METHODS:The L1-L3 finite element models of osteoporosis were established,and the vertebral compression fractures were simulated in L2.Four distribution patterns bilateral partial fusion(FH type),full fusion(FO type),symmetrical separation(SA type),and asymmetric segregation(SN type)were simulated in 4 and 6 mL injections in the osteoporotic vertebral compression fracture models,respectively,and a total of nine sets of models were obtained.These models were solved under the same boundary conditions and compared with the stress and displacement of the L2 fractural vertebra. RESULTS AND CONCLUSION:(1)The maximum stresses of the nine groups of models were concentrated in the L2 fractural area,and the maximum stress and maximum displacement of each filling model were lower than in the osteoporotic vertebral compression fracture model,indicating the effectiveness of bone cement filling in the treatment of osteoporotic vertebral compression fracture.(2)Compared with 4 mL bone cement filling,6 mL bone cement filling could significantly reduce the stress of fractured vertebrae and enhance the strength of fractured vertebrae while improving the stability of fractured vertebrae.(3)In the same state of movement,the FH type stress was the least,followed by the SA type,both of which were close.FO type stress was the largest,especially in the lateral bend,which might be associated with its cluster shape resulting in the concentration of lateral stress.In the aspect of displacement,FH type was the least and FO type was the largest.(4)The results show that increased dose of bone cement injection reduces fractural vertebral stress and improves stability,but increases the risk of leakage.Bilateral symmetrical dispersed bone cement(FH type,SA type)is superior in restoring vertebral strength and stability than full fusion(FO type),asymmetric separated(SN type)bone cement.Therefore,when clinically performing bilateral percutaneous vertebral augmentation treatment of osteoporotic vertebral compression fractures,the bilateral symmetric dispersions of the distribution are first guaranteed;priority is recommended for FH type distribution,for appropriate stress stimulation and best stability.

ObjectiveTo analyze the polarized light microscopic characteristics， the composition of physical phases and their relative contents of Maifanitum from different origins， and to establish the Fourier characteristic fingerprint of Maifanitum powder crystals by X-ray diffraction（XRD）. MethodA total of 26 batches of Maifanitum samples were selected， and the microscopic characteristics of the sample powders and grinding flakes were observed by polarized light microscopy under single polarized light and orthogonal polarized light， and the main phase compositions and their relative contents were analyzed by powder crystal XRD technique， and the XRD Fourier characteristic fingerprint of Maifanitum was established. The incident light source of XRD was Cu target Kβ radiation， the light tube voltage and light tube current were 40 kV and 40 mA， respectively， the divergence slit was 1°， the scattering slit was 1°， the receiving slit was 0.2 mm， the scanning speed was 5°·min^-1 with continuous scanning and scanning range of 5-90°（2θ）， and the step length was 0.02°. ResultThe polarized light micrographs of powders and grinding flakes of Maifanitum were obtained， and the main phases were plagioclase， potassium feldspar and quartz， and a few samples also contained illite， pyrite， iron dolomite， calcite， iron amphibole and chlorite， etc. The relative total content of feldspar phases was 61.9%-82.4%， and the relative content of quartz was 12.6%-33.6%. The XRD Fourier fingerprint analysis method of Maifanitum with 13 common peaks as the characteristic fingerprint information was established， and the similarity calculated by the mean correlation coefficient method was 0.920 9-0.997 7， the similarity calculated by the mean angle cosine method was 0.940 5-0.998 4， the similarity calculated by the median correlation coefficient method was 0.921 1-0.997 5， and the similarity calculated by the median angle cosine method was 0.947 5-0.998 2. ConclusionThe polarized light microscopic identification characteristics of Maifanitum are mainly plagioclase， quartz and potassium feldspar， and the technique of powder crystal XRD Fourier fingerprint analysis can be used for the identification of Maifanitum.