胫骨远端后内侧解剖钢板的设计与生物力学研究*

目的测试自制胫骨远端后内侧解剖钢板的力学性能，为临床应用提供科学依据。方法根据胫骨远端后内侧解剖特征设计出后内侧解剖钢板，新鲜胫骨各6具造成相同的胫骨远端骨折，分别行后内侧解剖钢板和外侧钢板内固定后，通过轴向压缩试验，三点弯曲试验，扭转力学性能试验来进行两种固定方法的生物力学研究，数据采用SPSS13．0分析。结果后内侧解剖钢板在三点弯曲、轴向压缩、扭转力学试验与外侧钢板之间均无差异（P〉0．05）。结论胫骨远端后内侧解剖钢板能够为治疗胫骨远端骨折提供一种新型的内固定材料，来弥补外侧解剖钢板在临床应用的局限性。     

纵向生理加压外固定器的生物力学分析

背景：目前骨外固定器大多为刚性结构,对骨折端存在过多的应力遮挡,影响骨折愈合速度及骨痂质量,甚至骨折发生不愈合。 目的：观察纵向生理加压外固定器固定胫骨中段横断骨折后与人体正常胫骨生物力学强度的差异。 方法：选取12根新鲜胫骨标本随机分为试验组和对照组,试验组分别用线锯造成胫骨中段横断骨折,纵向生理加压外固定器固定;对照组即正常胫骨。分别进行轴向载荷、弯曲载荷、扭转载荷作用下的力学实验,记录每一级加载后胫骨的位移及扭转角度,计算出轴向压缩刚度、弯曲刚度及扭转刚度。 结果与结论：在生理范围内加载下,试验左右应变略大于对照组,但其固定后整体刚度与对照组无显著性差异(P > 0.05);试验组的弯曲应变大于对照组,但其整体刚度与对照组无显著性差异(P > 0.05);两组整体扭转刚度无明显差异(P > 0.05);试验组极限弯曲载荷明显大于对照组(P < 0.05)。提示纵向生理加压外固定器能够达到足够的生物力学强度,有良好的稳定性,对骨折能起到生物学固定。     

新型点接触锁定加压接骨板的生物力学研究

目的对一种集合点状接触、锁定及加压于一体的新型接骨板(PC-LCP),进行弯曲力学特性、生物力学稳定性测试评估。方法对三种医用不锈钢接骨板,点接触锁定加压接骨板(PC-LCP)、有限接触动力加压接骨板(LC- DCP)、动力加压接骨板(DCP)各3副进行四点弯曲试验;20对新鲜山羊胫骨制成横断骨折,应用三种接骨板固定,进行四点弯曲、扭转及垂直压缩试验。结果PC-LCP弯曲刚度弱于DCP、LC-DCP,三者有显著差异(P<0.05),但三种接骨板固定骨折后的生物力学特性没有显著差异。结论强度稍低的新型接骨板PC-LCP固定骨折后与其它两种接骨板有同样的生物力学强度及较好的力学稳定性。     

骨干骨折压力侧皮质缺损钢板内固定的生物力学研究

目的 :评价压力侧骨皮质缺损时钢板内固定的即刻稳定程度 ,明确压力侧皮质骨块复位的重要性。方法 :6具新鲜股骨标本 ,于中段造成蝶形皮质缺损 ,测定正常股骨 ,单纯钢板内固定及对侧皮质骨块复位钢板内固定的垂直压缩、三点弯曲及抗扭转能力 ,比较不同固定方法在相同载荷下的位移。结果 :正常股骨在 5 0 0N垂直压力下的垂直位移 ,3 0 0N压力下的三点弯曲位移及 10N .m下的旋转角位移分别为 0 .82mm ,1.5 6mm和 0 .82° ,仅应用钢板于张力侧内固定后的三项位移分别为 8.2 9mm ,10 .5 9mm和9.11° ,应用钢板内固定对侧皮质骨块复位后分别为 1.78mm ,5 .15mm和 6.75° ,三项指标间均有非常显著性差异。结论 :当存在压力侧骨皮质缺损时 ,钢板固定骨块复位时的稳定性较单纯应用钢板内固定时好。应重视恢复钢板对侧皮质骨块的复位 ,恢复内侧的支撑力 ,以防止内固定的失败     

海藻酸钠为主体胶黏合骨碎块的体外实验

背景:粉碎性骨折比较理想的治疗方式是应用胶黏剂直接黏合骨碎块,医用黏合剂在临床上已广泛应用。但利用植物中提取的生物胶用于骨折块的固定治疗目前未见报道。目的:采用海藻酸钠胶为主体材料,改性后加入增黏剂、固化剂进行固定骨折块的体外实验,并观察其黏结效果。方法:取市售新鲜猪股骨皮质骨标本,制备成大小约2cm2的骨片。以海藻酸钠为主体胶,分别与羧甲基纤维素钠和瓜儿胶按适当比例混和,用其黏合猪股骨断面面积为1cm2左右大小的皮质骨块,然后用氯化钙溶液固化,分别测试实验当天和浸泡于生理盐水1,2,3周后骨块的剪切应力。结果与结论:两种混合胶的黏合力随着时间的推移呈正态分布曲线,在1周后达到最高峰,剪应力达到17000σ/Pa,之后逐渐下降,黏剂完全有能力粘固断面面积1cm2左右大小的骨块。提示海藻酸钠改性后加入适当增黏剂,可以起到固定小骨块的作用。     

人胫骨四种内固定器的生物力学评价

目的 :比较四种内固定器在人胫骨骨折时的生物力学特性。方法 :将经防腐固定成人胫骨9根 ,制成中段横断骨折 ,依次安放双Ender钉 ,双矩形钉 ,梅花钉和四孔钢板 ,并进行前内侧和前外侧三点弯曲实验及轴向扭转实验。结果 :Ender钉、四孔钢板、梅花钉和矩形钉内固定器的三点弯曲刚度分别为 :前外侧 13 .0、2 5 .4、41.8、2 3 .3N/mm ;前内侧 2 5 .5、 16.2、41.4、2 0 .2N/mm ;轴向扭转 15°时的力矩分别为 :1.43、4.67、0 .86、0 .86Nm。梅花钉抗弯曲较其它内固定器强 (P <0 .0 1～ 0 .0 5 ) ,余者间无显著性差别 ;四孔钢板抗轴向扭转较其它内固定器强 (P <0 .0 1) ,Ender钉次之。结论 :4种内固定器中四孔钢板抗轴向扭转性能最好 ,梅花钉的三点弯曲刚度最强 ,对于胫骨骨折 ,Ender钉和矩形钉可以提供较好的稳定作用。     

新型点状接触动力加压接骨板的研制(生物力学部分)

目的:研制一种可对骨折断端动力加压的点状接触接骨板,对其加压特性及固定的力学稳定性进行评价。方法:使用测加压力装置,比较一颗螺钉动力位加压时动力加压钢板及点状接触动力加压接骨板的加压力。使用山羊新鲜配对胫骨20对,做成横断骨折模型,分别用DCP及PC-DCP加压固定和骨折断端存在3mm间隙情况下固定,在多功能力学试验机上进行四点弯曲实验及扭转实验。结果:PC-DCP与DCP之间加压力无显著性差异(p>0.05)。PC-DCP固定的抗弯刚度稍大于DCP,抗扭刚度较DCP稍降低,但两者之间差异均无显著性(p>0.05)。结论:PC-DCP可对骨折断端有效加压,具有与DCP相似的力学稳定性。     

a-氰基丙烯酸正辛酯反复粘接人胫骨皮质骨的生物力学研究

在医用粘接胶固定骨折断端时,往往需要反复粘接固定才能达到满意的复位效果。本实验将新鲜人胫骨干复温后,于胫骨中段横断,取前方的皮质骨制成规则的三棱形,仔细处理断端骨面及三棱形的侧面,测量其面积后用于抗拉强度、剪切强度和弯曲强度的测定。在37℃生理盐水中用细砂纸打磨粘接面去除残余于骨面的胶体后,拭干各粘接面,再次测定抗拉、剪切、弯曲等指标,观察其变化。结果显示,第一次粘接的剪切强度大于第二次的剪切强度,二者之间有显著差异(P<0．05);第二次粘接的剪切强度大于第三次粘接的剪切强度,但无统计学显著差异(P>0．05);抗拉强度随粘接次数增加而减小,但各组之间无显著差异(P>0．05);在胶体断裂前,其弹性模量和刚度系数无显著差异(P>0．05)。在本实验中,初次粘接的抗拉强度为5．93 MPa,剪切强度为9．11 MPa,剪切实验中,被粘接的骨面的微形态结构的变化对剪切强度影响较大。在剪切强度的测定中,每次测定应去除1～2 mm的粘接面的骨质,以保证实验结果的可靠性。而拉伸试验和弯曲试验中,由于粘接面微形态结构的变化对实验结果无显著影响,去除骨面残留的胶体后即可进行反复实验。在临床操作中,对于剪切应力较大的部位,应一次粘接固定,以免反复粘接后影响粘接的固定效果。     

新型外固定系统在胫骨骨折上的生物力学研究

目的将新研制出的一种可实现三维空间万向调节的新型外固定支架系统进行生物力学特性的测试,评定该外固定支架系统的有效性,为临床研究提供可靠的理论依据。方法选取10具新鲜成年男性尸体的胫骨标本,制成横断胫骨骨折模型。实验组用自行研制的外固定系统进行骨折固定,对照组采用临床常用的Hoffman 2型外固定支架;对固定好的胫骨骨折模型行轴向压缩、扭转实验,并将测试所得数据结果进行统计学分析。结果 2组在轴向压缩、水平扭转方面比较,差异无统计学意义(P0.05),说明新型外固定支架系统与临床常用的Hoffman 2型外固定支架的轴向压缩、抗扭转方面无差异,符合临床应用标准。结论新型外固定支架系统的设计能够满足骨折固定对生物力学的要求,为骨折外固定提供了更多的选择。     

异种骨内固定器力学性能的实验研究

目的了解牛骨材料及其构件的力学强度[抗拉、抗压、抗折(弯曲)和抗扭(剪切)强度].方法将材料分为天然、处理和构件(即产品)三组并制成标准试件,用规定设备按标准方法进行检测.结果(1)牦牛股骨拉伸、压缩、抗折、扭转极限应力分别为106.35±3.45、127.60±2.65、225.9±4.1、53.45±1.55(MPa),胫骨拉伸、压缩、抗折、扭转极限应力分别为114.96±1.46、184.75±3.25、211.35±2.45、51.9±0.5(MPa).湖区水牛胫骨拉伸、压缩、抗折、扭转极限应力分别为1 28.1±11、195.8±9.4、167.4±1 2.7、54.25±0.75(MPa).(2)E0气薰灭菌对牛骨材料的力学性能无明显影响,幅照灭菌对牛骨材料的力学性能稍有影响.(3)处理后,牛骨螺钉、圆钉的抗折强度较材料有所降低,而抗拉强度、抗压强度、抗扭强度变化不大.结论牛骨是一种力学性能良好,适合制作内固定构件的高强度生物材料.     

Mechanical Evaluation of Large-Size Fourth-Generation Composite Femur and Tibia Models

Composite analogue bone models provide consistent geometric and structural properties that represent a valuable asset in a range of biomechanical analyses and testing procedures. The objective of this study was to evaluate the diaphyseal structural properties of the large-size Fourth-Generation composite analogue femur and tibia models concentrated on mechanical behaviors under axial compression, bending and torsion. Thirty of each large-size composite analogue models (femora and tibiae) were tested under medial-lateral four-point bending, anterior-posterior four-point bending, axial compression and external rotational torque to evaluate flexural rigidity, axial stiffness, torsional rigidity and ultimate failure strength. The composite femur was tested under torsion at both the femoral neck and the mid-diaphyseal areas. Large-size Fourth-Generation composite replicate bones exhibited intra-specimen variations under 10% for all cases and was also found to perform within the biological range of healthy adult bones (age: <80 years old) range with respect to flexural rigidity (<8%) and torsional rigidity (<12%). The failure modes of these composite models were close to published findings for human bones (four-point bending: butterfly fragment fracture; torsional: spiral fracture; and compression: transverse fracture). The large-size composite analogue femur and tibia are close to ideal replicas for standardization in biomechanical analyses. One advantage of these analogue models is that their variability is significantly lower than that of cadaveric specimens for all loading regimens. Published results vary widely in cadaveric studies, which is likely due to the high anatomic variability among cadaveric specimens. This study evaluated and advanced our overall understanding of the capacity of composite analogue bone models mimic the structural properties of average healthy adult human bones.     

股骨头松质骨力学性质实验研究

目的 研究股骨头松质骨力学性质，为临床提供生物力学参数。方法 对正常国人新鲜尸体股骨头松质骨的拉伸、压缩、扭转、剪切、弯曲、冲击力学性能进行实验研究。结果 得出了股骨头松质骨的拉伸、压缩破坏载荷、强度极限、弹性模量，扭转破坏扭矩、扭转剪切强度极限，弯曲破坏载荷、弯曲强度极限、剪切破坏载荷、剪切强度极限，冲击功、冲击韧性等测试指标的实验结果。结论 股骨头松质骨抗压强度大于抗拉强度，压缩弹性模量大于拉伸弹性模量，扭转强度大于剪切强度，抗弯强度与抗压强度接近。     

Morphological and radiological findings in induced abnormal bone growth in lambs

Unilateral hip excision arthroplasty in skeletally immature lambs resulted in altered load bearing and posture in the contralateral limb. Derangement of endochondral bone growth occurred in distal tibiae and metatarsi and both angular and torsional deformities developed. There was no absolute correlation between torsional and angular deformities. Although femoral torsion was variable, the unoperated pelvic limbs frequently developed exaggerated internal torsion of tibiae and metatarsi. Tibiae of operated limbs developed less torsion than was seen in control animals. These findings suggest that functional limb loading can modify developing bone torsion and that torsional deformities in lambs may be a consequence of increased functional torque.     

青年与老年肋骨扭转力学特性对比分析

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.     

Bonding strength of alkyl-2-cyanoacrylates to bone in vitro

This study measured the bonding strength between alkyl-2-cyanoacrylates and bone, and examined how treatment of the bone surface with acid, and prolonged exposure to moisture, affected this strength. The initial strength of all cyanoacrylates was high (9.6-11.2 N/mm2). In long-term experiments under water, n- and i-butylcyanoacrylates lost their strength at a far slower rate than ethylcyanoacrylates. However, the butylcyanoacrylates also showed a decrease of 15% in strength after three weeks. Pretreatment of the bone surface with acid did not have a marked effect on bonding strength, although SEM investigation revealed that the acid treatment had increased the porosity of the bone surface. A study of the fracture surface proved that the adhesive film tended to loosen or break after 3 to 6 weeks under water. The decrease in the bonding strength was probably due to the degradation of the adhesive film in water which loosened mechanical bonds between the bone and adhesive. Considering clinical use it would be necessary to achieve better long-term strength.     

压力对骨折愈合影响的实验研究

用带传感器的外固定架监测骨折端压力变化,比较了弹性加压外固定和一般外固定治疗兔胫骨中段横形截骨时,骨折端的愈合形式,骨痂抗扭功能恢复速率和应力遮挡保护作用出现的时间和强弱。6周时加压固定组一期愈合;骨痂抗扭强度为对照侧88.5%。非加压固定组二期愈合,骨痂抗扭强度是对照侧62.5%。12周时,去除压力组兔胫骨结构和功能均恢复正常,而持续加压组皮质骨疏松明显,强度为对照侧之73%。因此临床治疗骨折的早期,需给予压应力刺激;但应注意适时地去除压力和固定物,防止应力遮挡保护产生的副作用。     

The biocompatibility of materials for internal fixation of fractures

Surgically produced fractures of rabbit tibiae were internally stabilized with intramedullary rods of stainless steel (316LVM), titanium (6A1,4V), polyacetal (Delrin), and polyamide (Nylon 101). Periodic radiographs were taken until sacrifice at 16 weeks after fracture. Structural properties of the tibiae were determined in torsion with the rods in situ, and then the tissue was prepared for histology or microradiography. The results demonstrated that fracture remodeling was adversely affected by the metal rods. New bone was seen to have formed over the ends of the metal rods, and cortical bone resorption was observed in the fracture region, suggestive of transfer of mechanical stress to the rods, resulting in stress shielding of the diaphysis. Negligible osseous response to the polymeric rods was observed; fracture callus remodeling was extensive. The torsional test results demonstrated that fractures with polymeric rods were significantly stronger and tougher than those with metallic rods. With the exception of titanium, the strength of healed fractures was inversely related to the elastic moduli of the implant materials.     

The effect of two configuration factors,time, and thermal cycling on resin to dentin bond strengths

Most in vitro testing of bonding systems is performed using specimens made in a mold with a low configuration (C) factor (ratio of bonded/unbonded surfaces) whereas clinically the C-factor is usually much greater. This study compared the effect of thermal cycling on the measured shear bond strength of 3M Single Bond dental adhesive bonded to dentin using molds with two different C-factors. The hypothesis was that neither C-factor nor thermal cycling would affect measured bond strengths. Resin composite was bonded to human dentin in cylindrical molds with an internal diameter of 3.2mm and either 1mm or 2.5mm deep. The 1mm deep molds had a C-factor of 2.2 and the 2.5mm deep molds had a C-factor of 4.1. Specimens were debonded either 10min after they had been bonded to dentin, or after they had been stored for 7 days in water at 37+/-1 degrees C, or after thermal cycling 5000 times for 7 days. Two-way ANOVA showed that overall both the C-factor and the storage condition had a significant effect on bond strength (p<0.001). There was a significant interaction (p<0.001) between the C-factor and how the specimens had been stored. The GLM/LSMEANS procedure with Sidak's adjustment for multiple comparisons showed that overall the specimens made in the mold with a high C-factor (4.1) had a lower bond strength than those that had been made in the mold with a lower (2.2) C-factor (p<0.001). Thermal cycling had a negative effect on the bond strength only for specimens made in molds with a C-factor of 4.1 (p<0.001).