肾创伤的生物力学性质及其临床特点

目的总结肾创伤生物力学性质及其临床特点。方法回顾本院2000年1月至2006年1月间收治的326例肾创伤病例,分析创伤过程中生物力学因素发挥的临床效应。结果随着暴力动量的增大,肾创伤等级、肾切除率及死亡率均随之增高,有统计学意义(P＜0．05)。钝性暴力相对于锐性更容易造成闭合伤和合并伤,且肾切除率低,差异有统计学意义(P＜0．01)。后腰着力的肾伤情重于腹部正面或侧面着力,且合并伤发生率低(P＜0．05)。创伤瞬间速度变化的趋向对伤情等级、肾切除率及死亡率无明显影响(P＞0．05)。结论肾创伤过程中暴力的生物力学性质与其临床表现紧密相关。     

空心钉和骨圆针固定治疗股骨转子间骨折的力学随机对照试验

目的:通过与4枚斯氏针固定比较,利用生物力学方法评价多枚空心钉固定股骨转子骨折的适应证和可靠性。方法:使用Sawbone股骨模型,模拟EvansⅢA型骨折,分别用2种多枚空心钉方法(矩外空心钉和矩内空心钉法)及多枚骨圆针固定,在CSS-11101力学实验机上进行载荷试验,取300 N载荷下股骨头垂直位移和张口位移数值,比较3种方法的轴向刚度。通过扭转实验比较3种固定方法的抗扭转能力。结果:3种固定方法在轴向刚度方面差异有统计学意义(P<0.05),而抗扭转能力方面差异无统计学意义(P>0.05)。结论:矩外空心钉固定力学性能相似于4枚骨圆针,而矩内空心钉固定弱于4枚骨圆针。应用多枚空心钉固定应选择稳定型股骨转子间骨折。     

松质骨螺钉骨水泥强化的生物力学和组织学研究

目的通过动物实验观察不同骨水泥强化松质骨螺钉的生物力学和组织学变化动态,为骨质疏松骨折患者内固定提供理论基础。方法在10只杂种犬胫骨近端制作松质骨螺钉植入的动物模型,分别采用碳酸化羟基磷灰石水泥(CHC)和聚甲基丙烯酸甲酯(PMMA)强化,分别于术后5d、4、8、12和16周处死动物,观察螺钉拔出的生物力学和组织学变化。结果CHC强化的螺钉拔出力随手术后时间的延长而逐渐升高,16周时达到(512.5 14.5)N,而PMMA强化组螺钉拔出力则随手术后时间的延长而逐渐降低。CHC-骨界面结合紧密,并且随时间延长出现CHC降解和骨长入,而PMMA-骨界面形成一层纤维组织。结论CHC强化能够提高松质骨螺钉植入体内的稳定性,并且随植入时间延长而逐渐升高。     

Surgical Biomechanics of the Patellofemoral Joint

This review presents objective data, as far as possible, about the current understanding of the biomechanics of the patellofemoral joint as it pertains to the management of patellofemoral problems. When faced with a patellofemoral malfunction, it is important to check all the soft-tissue and articular geometry factors relating to the patella locally and not to neglect the overall lower limb alignment and function. It is important to remember that small alterations in alignment can result in significant alterations in patellofemoral joint stresses and that changes in the mechanics of the patellofemoral joint can also result in changes in the tibiofemoral compartments. Surgical intervention for patellofemoral problems needs to be planned carefully and take into account an individual’s anatomy.     

额、枕部直接冲击导致中脑损伤的力学机制研究

目的分析额、枕部直接冲击造成中脑应力响应,探讨颅脑直接冲击导致脑干损伤的力学机制。方法构建头颅三维有限元模型,模拟计算额、枕部直接冲击损伤,分析中脑上、下交界面节点应力分布,总结中脑应力响应。结果中脑-间脑界面在冲击初始阶段,2ms即出现应力增高,中脑-桥脑界面应力升高开始于冲击后期(10ms),两交界面节点应力在冲击时程中均持续升高,额部冲击比枕部冲击在中-间脑界面造成的应力峰值高。结论中脑在颅脑直接冲击伤的致伤机制中占有突出地位,中脑的应力改变可解释脑震荡的意识障碍及部分原发脑干伤的临床表现。     

镍钛记忆合金腕骨四角融合器的研制及生物力学测试

目的研究一种新的用于四角融合的内固定器械和方法.方法根据国人头状骨、月骨、三角骨和钩骨的测量数据及解剖特点,采用镍钛记忆合金制作腕骨四角融合器（NiTi shape memory alloyfour-corner arthrodesis concentrator,NT-FCAC）;取32侧成人头状骨、月骨、三角骨和钩骨标本,分别采用NT-FCAC和克氏针固定,体外模拟四角融合术,用858型双轴液压材料测试系统（858-MTS）测试其固定强度;2件NT-FCAC施加20～200N循环拉伸载荷（1Hz）,观察NT-FCAC的形变情况;分析试验结果,评价NT-FCAC的生物力学特性.结果NT-FCAC固定臂产生的回复力可将头状骨、月骨、三角骨和钩骨聚合于一体,体部可遮挡植入上述4处腕骨间关节间隙的松质骨,防止其滑脱;NT-FCAC组固定强度大于克氏针组（P＜0.05）;2件NT-FCAC发生形变达到6%时,施加的载荷次数分别为4 239次和4068次.结论NT-FCAC的设计符合头状骨、月骨、三角骨和钩骨的解剖特点,其固定强度可满足四角融合术后不需外固定、早期功能锻炼的生物力学要求,疲劳强度可满足四角融合术后达骨性愈合的需要.     

兔颈椎终板胶原结构变化对运动节段力学性能的影响

目的 通过测定兔退变颈椎运动节段力学参数的改变,观测其软骨终板胶原的超微结构变化,为退变的椎间盘显现异常力学特性作材料结构上的探讨。方法 将24只家兔随机分为对照组和模型组,模型组家兔保持45°低屈曲位5 h/d,取C5,6、C6,7进行生物力学测定,同时电镜观察终板胶原组织结构改变,总结分析终板材料的结构变化对运动节段力学性能的影响。结果 模型组终板抗扭强度、抗压强度、断裂时的最大形变都低于对照组,胶原排列从有序、致密、规整到紊乱、松散、溶解,并随造模进程的深入而加剧。结论 长时间的应力不均状态,造成椎间盘终板材料力学特性改变;终板胶原结构改变是颈椎间盘生物力学性能减退的原因之一。     

不同钉位布局影响股骨颈骨折内固定效应的生物力学研究

目的:观察应用多枚钉内固定治疗股骨颈骨折时采取不同钉位布局对骨折断端固定效应的影响,为临床操作中寻求最佳钉位布局奠定基础。方法:通过特制壮年人体尸骨股骨颈骨折模型,进行直视下解剖复位后,分别应用3钉倒三角形、3钉正三角形和双钉平行3种不同钉位布局内固定方法完成内固定。在生物力学万能试验机上进行轴向压缩和扭转实验,观察不同生物应力下断端相对的位移距离、轴向刚度、水平剪切刚度和扭转强度等项目,取得试验数据后经统计学处理,进行组间对比,观察其差异的显著性。结果:在3种钉位布局的内固定方法之中,以股骨矩核心下2～3mm处进钉位为下位顶点的倒三角形钉位布局能获得最坚强的固定效应,相同应力下其位移距离最小而各项刚度最大;而股骨矩核心上位和中下位双钉固定法固定效应最差,表现为相同应力下位移距离最大和各项刚度最小。结论:尽可能选择以股骨矩核心下2～3mm处进钉位为下位顶点的倒三角钉位布局法,尽可能减少应用双钉位布局法。     

Dynamic response of the occipito-atlanto-axial (C0-C1-C2) complex in right axial rotation.

The torque-angular deformation in right axial rotation until failure of the ligamentous occipito-atlanto-axial complex subjected to variable loading rate (dynamic) axial torque was characterized using a biaxial MTS system. A special fixture and gear box that permitted right axial rotation of the specimen until failure without imposing any additional constraints were used to obtain the data. The specimens were divided into three groups and tested until failure at three different dynamic loading rates: 50, 100, and 400 degrees/s. A previous study by the authors provided data for quasi-static (4 degrees/s) loading conditions. The torque versus rotation curves can be divided into two straight regions and two transition zones. The plots clearly indicated that at loading rates higher than 4 degrees/s, the specimens became stiffer in the region of steadily increasing resistance prior to failure. The increase in stiffness was maximum at 100 degrees/s. The stiffness decreased somewhat at 400 degrees/s in comparison with 100 degrees/s, but this decrease was not significant. The resulting torque-right axial rotation curves were also examined to estimate the magnitude of maximum resistance (torque) and the corresponding angular rotation value. The average maximum resistance torque increased from 13.6 Nm at 4 degrees/s to 27.8 Nm at 100 degrees/s. The corresponding right angular rotation data (65-78 degrees), however, did not show any significant variation with loading rate. Posttest dissection of the specimens indicated that the type of injury observed was related to the rate of axial loading imposed on a specimen during testing.(ABSTRACT TRUNCATED AT 250 WORDS)     

Effect of autocontrol micromotion intramedullary interlocking nail on fracture healing： an experimental study

Objective: To investigate the effect of autocontrol micromotion locking nail ( AMLN ) on experimental fracture healing and its mechanism. Methods: 16 goats undergoing both sides of transverse osteotomy of the femoral shafts were fixed intramedullary with AMLN and Gross-Kempf (GK) nail, respectively. The follow-up time was 7, 14, 28 and 56 days. Roentgenographic, biomechanical, histological, scanning electromicroscopic and biochemical analyses were done. Results: (1) The strength of anticompression, antiflexion and antitorsion in the fractural end in the AMLN-fixed group was higher than that of GK nail-fixed group; whereas, the rate of stress shelter in the fractured end decreased significantly (P<0.01). (2) The content of the total collagen, insoluble collagen, calcium and phosphate in the AMLN-fixed group was higher than that in the GK nail-fixed group (P<0.05). (3) Histological observation and quantitative analysis of calluses revealed that AMLN could promote the growth of bridge calluses and periosteum calluses. Hence the facture healing and remolding process achieved early, which was much better than traditional GK nail fixation. (P<0.05). (4) 7-14 days postoperation, the calluses of AMLN-fixed group was flourish and camellarly arranged and the collagen fibril formed constantly in the absorption lacuna of bone trabecula. 28-56 days postoperation, the collagen fibril was flourish around the absorption lacuna and was parallel to the bone's longitudinal axis. Active bony absorption and formation were seen, so was remolding and rebuilding. Haversian system was intact and the bony structural net was very tenacious because of the deposition of calcium salt. None of the above findings was observed in the GK nailfixed group. Conclusions: The design of AMLN accords well with the plastic fixation theory. As the geometry ametabolic system constituted by the intramedullary fixation instruments and the proximal and distal end of the fracture is very firm and stable, the disturbance to the physical stress distributed in the fractural end is light. The generation and conduct of the intermittent physical stress between the fractural parts could reach the balance between stress conduct and stress protection. The feature that the healing and remolding take place at the same time speeds up the fractural healing process.