To establish the three -dimensional finite element model of sciatic nerve injury,and then calculate the stress and dis-placement at the site of anastomosis with the three -dimensional finite element analysis software and provide the basic biomechanical experiments for the injury of sciatic nerve transplantation.The three -dimensional finite element model with 5mm,10mm,15mm, 20mm of sciatic nerve injury nerve autograft were established,we applied 10N tensile load on the force model,the displacement and stress values around each measuring point were calculated by using the finite element software (PROE5.0).The maximum stress of transplantation group with 5 mm is greater than that in transplantation group with 10 mm,15 mm and 20 mm under the same load simu-lation of sciatic nerve injury with autologous nerve.The maximum displacement of transplantation group with 20 mm is greater than that in the transplantation group with 15 mm,10 mm and 5 mm in the presence of 10 kf simulation with autologous nerve injury of sciatic nerve.It is feasible for sciatic injury model by numerical calculation using three -dimensional finite element method.

目的：确定各种药物治疗动物骨质疏松的效果。方法以去卵巢法复制动物骨质疏松模型，以中药、西药、VK，钙剂进行治疗，饲养15 w后处死大鼠、取大鼠胫骨，采用德国蔡司公司生产的扫描电子显微镜观察各组大鼠胫骨纵断面的骨显微结构（骨小梁排列情况），采用成都泰盟公司BI-2000医学图像分析系统观察各组大鼠胫骨切片骨形态计量学指标。结果模型组骨小梁周长、骨小梁面积、骨小梁相对体积、骨小梁平均厚度、骨小梁平均间距小于正常对照组、中药组、西药组、维生素K（VK）组（P＜0.05）。模型组与钙剂组各项指标差异不显著（P＞0.05），模型组胫骨骨小梁排列稀疏，孔隙较大，正常对照组骨小梁细密，中药组、西药组，通过治疗骨小梁修复较好，钙剂组和VK组骨小梁排列有一定稀疏，有一定孔隙。结论模型组骨纤维结构发生改变，骨组织形态计量学指标发生改变；中药、西药治疗骨组骨组织形态计量学指标与正常对照组接近，中药、西药对治疗骨质疏松都具有一定效果。

OBJECTIVE:The study aims to compare the stress shielding effects of implantable anatomical and traditional prostheses after in vitro total hip joint replacement simulation. The study serves as a biomechanical basis for novel artificial prostheses and for clinical hip joint replacements.METHODS:Sixteen femoral specimens from adult male corpses were randomly divided into two groups: the traditional prosthesis group implanted into femur specimens using simulated total hip joint replacement (n = 8) and the femoral neck-preserved anatomical prosthesis implantation group that used a collum femoris preserving stem/trabeculae oriented pattern (CFP/TOP) acetabular cup (n = 8). The strain values in the two groups before and after prosthesis implantation were measured at different test points using electric resistance strain gauges. The stress shielding rate was calculated according to the related formula.RESULTS:The results showed that the rates of proximal femoral stress shielding were significantly higher at test points 1-10 in the traditional femoral prosthesis transplantation group than in the anatomical prosthesis group (p < 0.05).CONCLUSIONS:There were different effects of stress shielding between the anatomical and traditional prostheses. Retained femoral anatomical implants should reduce stress shielding and increase the stability of anatomical prosthesis implants.

To compare the big mouse's femur creep mechanical characteristic of the normal control group,the osteoporosis animal model one and the osteoporosis animal model in each treatment group and to determine the treatment effect.The osteoporosis animal model was copied by the ovariectomized method.The animals were treated by Chinese medicine、western medicine、VK and the calcium agent respectively.After 15 weeks,the big mouse was executed.The big mouse's femur was token out to do the creep experiment,the stress increasing speed of creep experiment was 0.01MR/s,the experiment time was 7 200 s(P0.05),100 data were gathered.The creep experiment data and curves were recorded,the empirical datum was done by three parameter model processing.The stress relaxation quantity difference of normal control group treated by Chinese native medicine,western medicine one were not remarkable in 7 200 s(P0.05),slow change quantity of the model one in 7 200 s was lower that of normal control one,the Chinese native medicine one and the western medicine one.The difference was remarkable(P0.05).The creep of VK group in 7 200 s was greater than that of the model one and the calciam agent one,the difference was remarkable(P0.05).The creep characteristics of big mouse of the treatment group by Chinese medicine and western medicine restore to their original level.The mouse's femur creep of recovery of the VK treated group has some recovery.The big mouse's creep characteristic of the model group has changed.

To compare the femoral lower cancellous bone vertical and lateral creep property of sample and provide biomechanical parameters of femoral lower cancellous bone.Before the test,specimens were removed at room temperature,10 thaw femoral lower specimens were taken,each specimen was processed with 20 mm width,20 mm length,20 mm high.First 10 samples were rested on longitudinal creep experiments.The stress increased speed of creep experiments was 0.01 MPa/s,setting time for 7 200 s,collecting 100 experimental data.The creep of the femoral lower cancellous bone longitudinal sample was 0.26% at 7 200 s.The creep of transverse was 0.33% at 7 200 s.Creep curves were based on the relation of index.The creep of lower lateral femoral cancellous bone at 7 200 s was bigger than that of vertical.The horizontal and vertical of the femoral below cancellous bone are different in the creep property,and it is anisotropic viscoelastic material.

BACKGROUND:Bone mechanics is a branch of biomechanics.Biomechanical property research of fractures after internal and external fixation is an important method to estimate the fixed-effects.OBJECTIVE:To compare the stress relaxation properties of tibial fractures fixed by three different internal and external fixation devices.METHODS:The simulated tibial fractures were fixed by the intramedullary nails,plate,and external fixation respectively.Axial compression stress relaxation experiment was performed in the specimens of the three groups using electronic universal testing machine.RESULTS AND CONCLUSION:Axial compression stress relaxation curves of the specimens fixed with internal and external fixation in each group showed that the stress relaxation at 7 200 s in the external fixation group was higher than those of the plate fixation group and the intramedullary nail fixation group,but the differences were not significant (P>0.05).The results preliminary showed that the effects of plate fixation,intramedullary nail fixation,and external fixation on stress relaxation property of bone in femoral neck fractures were similar.

BACKGROUND: Trauma and degeneration of cervical vertebrae can make cervical vertebra loses stability. That need the operation treatment, and sometimes need removal of the small joint. There are few studies on evaluation of the creep characteristics after separate resection of small joint at present. OBJECTIVE: To compare normal cervical samples with the removal of cervical C5-6 facet joint stress relaxation of the creep mechanical properties, to determine whether the removal of the facet joint have an impact on stress relaxation properties. METHODS: Creep test on the removal of the normal facet joint specimens and the normal specimens was done on Japan shimadzu electronic universal testing aircraft. Temperature of human body on (36.5±0.5) ℃ in temperature field was simulated, stress on specimens by the speed of 5%/s was imposed, the time for 7 200 s was set. Creep equation from 100 data was calculated by three-parameter model. RESULTS AND CONCLUSION: The creep curve of normal specimens and the removal of the cervical facet joint were changed by the index relationship. It changed rapidly in the initial 600 s. With the extension of the time, the strain decline into the final phase of the balance slowly. The creep had no significant difference between the normal specimens and the removal of the cervical facet joint specimens in 7 200 s (P < 0.05). The calculation of the three-parameter model is simple, can be good fit changes in the strain curve. From this ideal equation, quantitative differences between the two groups are not significant.

BACKGROUND:Similar to other soft tissues,ligament has viscoelasticity.The stress relaxation and creep viscoelasticity of ligaments are based on human physiologic functions.Studies have demonstrated that osteoarthritis has effect on ligament mechanical property.OBJECTIVE:To compare stress relaxation rheological properties of medial collateral ligament(MCL) between normal and osteoarthritis animal models,to determine the influence of osteoarthritis on MCL ligament stress relaxation characteristics.METHODS:Animal osteoarthritis models were prepared by closed joint Nick method.Each 10 MCL samples were taken from normal and osteoarthritis rats for stress relaxation experiments.The strain increase rate was 5%/s,and test duration was 7 200 s,a total of 100 data were collected.The stress relaxation data,and change laws of curves,stress and time were observed.All data were analyzed by one linear regression.RESULTS AND CONCLUSION:The stress relaxation of the normal and model groups changed fast at the initial 600 s,followed by a slow decrease.The stress relaxation of the normal group at 7 200 s was 4.69 MPa,and the model group was 0.29 MPa.The 7 200 s stress relaxation quantity of the model group was obviously smaller than that of the normal group(P < 0.05).The stress relaxation curves were changed in a log relationship.The knee osteoarthritis can decrease MCL stress relaxation,which influences LCL stress relaxation characteristics.

对正常和坏死股骨头进行蠕变实验,为新型人工关节的研究和髋关节置换术提供蠕变力学特性参数.8个正常股骨头实验标本取自正常人新鲜尸体,男性,年龄22～28岁;8个股骨头坏死样本为股骨头坏死病人进行人工髋关节置换术后所遗弃,也为男性,年龄28～56岁.利用日本岛津电子万能试验机,在(36.5±0.5)℃条件下,以0.5MPa/s的应力增加速度对标本施加压力.在7200s的试验时间内,采集100个实验数据,描绘出蠕变曲线并计算蠕变参数.实验结果表明所有样本在最初600s内蠕变速度较快,之后缓慢上升,7200s时蠕变曲线基本保持平衡,蠕变量与时间呈指数关系.坏死组股骨头7200s蠕变量为0.61%,显著低于正常组的0.85%(P<0.05).此结果证实股骨头坏死后其蠕变力学特性发生改变.

目的 比较正常和骨性关节炎动物模型膝关节内侧副韧带的蠕变特性,确定骨性关节炎对内侧副韧带蠕变特性的影响.方法 在日本岛津电子万能试验机上对正常和病态组各10个试样进行蠕变实验.蠕变实验的应力增加速度为0.01 mPa/s.设定实验时间为7200 s,采集100个数,以归一化分析的方法处理实验数据.结果 正常和病态组内侧副韧带蠕变最初600 8变化较快,之后应变缓慢上升,正常组7200 s蠕变量1.622％,病态组7200s蠕变量1.146％.结论 蠕变曲线是以指数关系变化的,骨性关节炎对膝关节内侧副韧带蠕变特性具有一定影响.

To compare the nature of stress relaxation of normal femoral head and necrosis femoral head to provide the stress relaxation parameter for the artificial joint research and the hip replacement.The stress relaxation experiment was carried on the Daojin electron universal testing machines of Japan with respecticrely 8 specimens of normal femoral head and necrosis femoral head.The experiment was carried on in 36.5℃ simulating human body temperature,5%/s strain rate of increased was imposed on the specimen strain,the hypothesis time as 7 200 s,100 empirical data were gathed.Three parameter model computation stress relaxation equation was used.The stress relaxation curve and stress relaxation quantity at 7 200 s were observed.The stock bone had rapid changes during the first 600 s,afterwards the stress decreased slowly,the stress relaxation quantity of the normal group at 7 200 s was 0.31 MPa,the stress relaxation quantity of the morbid state group at 7 200 s was 0.22 MPa,the stress relaxation quantity of the morbid state group at 7 200 s was obviously lower than the normal group(P0.05).After stock bone necrosis disrupted the normal arrangement of trabecular bone,the bone quantity lost,thus had the influence on the counter stress relaxation characteristic.The stress relaxation data may proves that stress relaxation characteristic of necrosis stock bone is bad.

BACKGROUND:Studies on surgery for sacral fracture and S2 sacral pedicle screw fixation have been conducted.However,the strain distribution rule of sacrum under maximum pulling-out force of S2 sacral pedicle screw is rarely reported.OBJECTIVE:To explore the pulling-out force of S2 sacral pedicle screw and the strain distribution of sacrum so as to provide biomechanical parameters for clinical fixation.METHODS:Fresh sacrum specimens from fresh corpses of normal people,with the method of S2 sacral pedicle screw fixation outside.The small sensors were connected to fixation device of pedicle screw to measure the tightening force of pedicle screw.At the same time,the electric strain on the strain gauge of different parts which was resistance to static and dynamic strain gauge pre-pasted on the four fixed-site edge of pedicle and the different parts of sacrum was measured using the resistance strain gauge.The entry point of screw 1 was the lowest point of the inferior margin of left first posterior sacral foramina;screw 2 was the lowest point of the inferior margin of right first posterior sacral foramina;screw 3 was the intersection point of left first posterior sacral foramina and lateral sacral crest;screw 4 was the intersection point of right first posterior sacral foramina and lateral sacral crest.Maximum pulling-out forces of pedicle screw and strain distribution values of the different points of sacrum were measured.RESULTS AND CONCLUSION:The screw pulling-out force of screws 1,2,3 and 4 were(3997.2) N,(281.05.2) N,(196 4.3) N,and(2014.6) N,respectively.The minimum strain was found in the 8th measurement point of screw 2(13.51.1),and the maximum strain was found in the 1st measurement point of screw 1(96.86.5).These findings indicate that S2 sacral pedicle screw procedure accords with the biomechanical principle.

选择胸椎骨折固定器需要了解肋骨的力学特性.本文对正常国人青年和老年尸体肋骨进行扭转实验,并对比分析青年和老年尸体肋骨的扭转力学特性,为临床提供生物力学参数.实验标本取自4具正常国人男性新鲜尸体肋骨,年龄分别为23岁、27岁、72岁、76岁,根据年龄分为青年组和老年组.以肋骨标本沿纵向切成长55mm的样本试样,每组各20个.实验环境温度为20℃,将样本两端装夹于扭转试验机的夹头内,以1°/s的扭转速度对试样施加扭矩,测试样本破坏后的最大扭矩和最大扭转角值,并计算其扭转切应力,同时观察样本破坏断口的形貌.实验结果表明,青年组肋骨最大扭矩、切应力和扭转角均大于老年组,有显著性差异(P < 0.05),因此青年组和老年组肋骨具有不同的扭转力学特性.样本断口形貌显示,2组样本断口多数为斜型,少数为横型.大体观察,青年组肋骨骨小梁排列细密,老年组肋骨骨小梁排列稀疏,具有老年骨质疏松的特征.

BACKGROUND:Spinal cord injury lead to muscular atrophy of lower extremity and evoke osteoporosis following a long duration.It is necessary to study the mechanical properties of animal models with osteoporosis secondary to spinal cord injury.OBJECTIVE:To observe spinal cord injury-induced mechanical changes of vertebra.METHODS:Totally 66 Wistar,male,rats were randomly divided into the control and model groups.Spinal cord was injured by cutting vertebral plate at T10 centrum horizontally.L1-4 vertebra was harvested at 11 weeks after model preparation for compression,torsion and impulse tests.RESULTS AND CONCLUSION:Compared with the control group,the maximum load,maximum stress,maximum torque,maximum stress,maximum torsion angle,maximum impact energy,and maximum impact toughness of the model group were smaller (P<0.05),suggesting that there are variations in compression,torsion and impulse features of rat vertebra osteoporosis secondary to spinal cord injury.

背景:骨质疏松的预防、诊断和治疗都需要了解药物治疗的效果。扭转力学性能指标是对药物治疗后骨质疏松质量评价的一种可靠方法。目的:观察不同药物治疗动物骨质疏松的疗效。方法:四五月龄雌性Wistar大鼠建立骨质疏松模型,以复方中药、阿仑膦酸钠、维生素K、钙剂进行治疗,饲养15周后处死大鼠,取大鼠股骨在扭转试验机上以1（°）/s进行扭转实验,实验结束后通过试验机测量变盘读取转矩和扭转角数据,试样破坏后观察试样的断口形貌。结果与结论:骨质疏松大鼠最大转矩、扭转角、切应力均低于正常大鼠（P＜0.05）,而经过复方中药或阿仑膦酸钠治疗后,最大转矩、扭转角、切应力得到恢复,但维生素K及钙剂治疗效果不明显。说明中药、西药、维生素K治疗动物骨质疏松模型大鼠均有一定疗效,钙剂效果不明显,中药的效果最好。

Background: Both the studies of artificial joints and femoral and neck fracture fixation need to know the femoral neck cancellous bone creep mechanical properties. Objective: To quantitatively investigate the time-dependent variation of femoral neck creep. Methods: Creep experiments were conducted on eight femoral neck cancellous bone specimen using an electronic all-powerful machine. The experiments were performed at 36.5 °C as the body temperature, and the stress speed was 0.11 MPa/s. The experiment duration was 7 200 s. On hundred experiment data were collected and processed based on a three-parameter model. Results and Conclusion: The femoral neck cancellous bone creep changed quickly within initially 600 s, and then went up slowly. The creep amount was 0.84%. The creep curves changed in an index manner, and the three-parameter model was very good to fit the creep curves and equations of the femoral neck cancellous bone.

BACKGROUND: The creep characteristics of cancellous bone from necrotic femoral head are important for clinical artificial joint replacement. Therefore, it is necessary to study mechanical properties of cancellous bone at 45 ° direction. OBJECTIVE: To compare creep properties of normal femoral head and necrotic femoral head at 45 ° direction based on three-parameter model established creep equation. METHODS: A total of 8 normal and 8 necrotic femoral heads were used. The cancellous bone was harvested at 45 ° and subjected to creep test on electronic universal testing machine. With simulated temperature field of human body temperature at 36.5 °C, stress was imposed on the samples by an increase of 5%/s for 7 200 seconds. 100 experimental data were collected, and stress relaxation equation was calculated using three-parameter model. RESULTS AND CONCLUSION: The creep curve of the femoral head of normal and necrotic changes was exponential relation. Changes were fast in the first 600 seconds, and strain increased slowly with time, finally entered into balance stage. 7 200 s creep of cancellous bone from necrotic femoral head was less than normal femoral head cancellous bone. Three-parameter model calculation is simple and can well fit the creep of changes in the femoral head. The establishment of such idealized equation quantitatively shows poor visco-elasticity of the necrotic femoral head.

目的 腰椎松质骨的冲击力学特性对治疗骨质疏松、骨重建、骨再造以及人工关节置换术等具有重要的临床意义,本文对正常国人青年和老年新鲜尸体腰椎松质骨进行冲击试验,通过分析确定老年腰椎松质骨和青年尸体腰椎松质骨是否具有不同的冲击力学特性.方法 死后1h之内解剖取出青年和老年死者腰椎L1-L5标本,并将标本沿纵向切成长30mm、宽5mm、高5mm的试样共40个,按年龄分青年和老年组各20个样本.以能量释放方法对2组样本进行冲击实验,根据试验机显示出的样本承受的冲击功,利用材料力学中的数学公式计算出每个样本的冲击韧性.结果 青年组腰椎松质骨承受的冲击功为(35.92±3.26)N·mm,冲击韧性为(1.44±0.13)N·cm/mm2;老年组的冲击功为(28.2±2 94)N·mm,冲击韧性为(1.14±0.11)N·cm/mm2.结论 老年组腰椎松质骨的冲击力学特性因老年性骨质疏松发生一定变化,其冲击力学性能显著降低.