应力松弛接骨板对骨应力遮挡率影响的实验研究

将螺孔部衬有不同数量、不同厚度聚乙烯垫圈的３１６Ｌ不锈钢接骨板置于２０根聚甲基丙烯酸甲酯模拟骨中段。分别在固定后不同时期测定不同载荷下接骨板内二螺孔间的外表面及接骨板对侧模拟骨中段的应变值，从而计算出应力遮挡率。结果发现，有垫与无垫接骨板组在术后１０周内的应力遮挡率无统计学差异，１０周以后两组间出现显著性差异，无垫组保持不变，有垫组的应力遮挡率逐渐下降。在垫圈厚度相同时，衬垫数量越多（本实验最多采用４孔４垫），后期应力遮挡率下降越明显。表明应力遮挡率的变化与垫圈数量关系密切。     

可变刚度接骨板系统对循环压缩载荷的力学反应

为了防止或减轻坚硬接骨板固定后局部骨质疏松，我们在普通接骨板的螺孔与螺钉间加一粘弹性材料制成的垫圈，而形成可变刚度接骨板系统，本文通过体外模拟试验，分析其对循环压缩载荷的反应。结果发现：此系统承受１０￣５次压缩载荷后，固定刚度仍确实可靠。以后随着加载次数的继续增加，至２Ｘ１０￣５次后，其固定刚度逐渐下降，应力遮挡率明显降低，具有较好的临床相关性。分析其机理在于垫圈材料的疲劳破坏引起螺钉松动所致。     

可变刚度接骨板系统对循环压缩载荷的力学反应

为了防止或减轻坚硬接骨板固定后局部骨质疏松，我们在普通接骨板的螺孔与螺钉间加一粘弹性材料制成的垫圈，而形成可变刚度接骨板系统，本文通过体外模拟试验，分析其对循环压缩载荷的反应。结果发现：此系统承受１０￣５次压缩载荷后，固定刚度仍确实可靠。以后随着加载次数的继续增加，至２Ｘ１０￣５次后，其固定刚度逐渐下降，应力遮挡率明显降低，具有较好的临床相关性。分析其机理在于垫圈材料的疲劳破坏引起螺钉松动所致。     

低应力遮挡效应接骨板的研究与设计

在骨折的治疗中,接骨板的应用最为普遍,接骨板种类繁多,出现问题也较多,比如断钉、断钢板、骨折不愈合、骨质愈合不良等问题。为了有效降低上述问题发生,促进骨愈合我们研究设计了低应力遮挡效应接骨板。1构造1.1低应力遮挡效应接骨板的螺孔为长方形或长椭圆     

形状记忆锯齿臂环抱内固定器的稳定性研究

本文采用５２根犬股骨作中段截骨，分别以新设计的形状记忆锯齿臂环抱内固定器、接骨板和髓内钉进行固定。然后对三种固定方法对固定骨段的应力遮挡率、不同加载方向的弯曲强度和扭转强度进行测试。试验证实环抱器有良好的抱持力，固定后其抗弯强度与接骨板无明显差异，而其应力遮挡率却明显低于接骨板（ｐ＜０．０１），同时抗扭作用又明显高于髓内钉（ｐ＜０．０１）。上述结果提示，环抱器可在对骨折提供可靠固定的同时，避免接骨板所致的应力遮挡性骨质疏松，具备髓内钉所没有的良好抗扭能力，并在安放时不损伤髓内血供和骨膜，具有良好的应用前景。     

应力松驰接骨板对固定段骨结构及力学性能影响的实验研究

目的:了解应力松驰接骨板固定对固定段骨形态结构及力学性能的影响.方法:分别将应力松驰接骨板(实验组)和坚硬接骨板(对照组)固定于兔胫骨干中段,采用CT扫描及CT值测定和力学测试,观察固定段骨结构及力学性能的变化.结果:固定后8～12周,两组板下皮质骨厚度均逐渐变薄,伴CT值和固定骨段力学强度下降,以对照组为明显.24～36周,实验组板上皮质骨厚度、CT值和固定骨段力学强度逐渐恢复,接近正常;而对照组呈现松质骨化,36周时最大三点弯曲强度仅为正值53.9%.结论:应力松驰接骨板减轻了板下骨骨质疏松的发生,在不去除接骨板的情况下,可使疏松板下骨形态结构及力学性能逐渐恢复.     

应力松驰接骨板对固定段骨结构及力学性能影响的实验 …

目的：了解应力松驰接骨板固定对固定段骨形态结构及力学性能的影响。方法：分别将应力松驰接骨板（实验组）和坚硬接骨板（对照组）固定于兔胫骨干中段,采用ＣＴ扫描及ＣＴ值测定和力学测试,观察固定段骨结构及力学性能的变化。结果：固定后８～１２周,两组板下皮质骨厚度均逐渐变薄,伴ＣＴ值和固定骨段力学强度下降,以对照组为明显。２４～２６周,实验组板上皮质骨厚度、ＣＴ值和固定骨段力学强度逐渐恢复,接近正常;而对照     

锥状点式接触接骨板与普通接骨板的力学性能及对局部血流量影 …

为了比较锥状点式接触接骨板与普通接骨板的力学性能及对局部皮质微循环的影响，采用材料，尺寸完全一致的模拟骨，分别用两种有板固定，进行三点弯曲实验和扭转移实验比较二者的力学性能，另用１４只山羊，４只正常对照，１０只行胫骨中段横行截骨后分别用两种接骨板固定，术后３天，２周，４周和９周处死动物，用放射性微局部血流量测定法评价接骨板下和对侧皮腩骨血流量。结果发现：两种接骨板的抗弯能力无显著差异；当转角大于１     

有限元法分析不同固定方式在胫骨远端粉碎性骨折骨愈合中的生物力学差异

背景：胫骨远端粉碎性骨折伴软组织损伤的治疗具有挑战性，新型逆行胫骨髓内钉、外置接骨板是重要的治疗手段，但其在骨折愈合不同时期、不同负重情况时的骨折端应变、应力遮挡情况未见报道。目的：通过有限元分析法探讨骨折愈合不同时期逆行髓内钉及外置接骨板的生物力学差异，为临床应用及康复锻炼提供科学参考。方法：利用1名40岁健康男性的胫骨CT数据，建立胫骨远端粉碎骨折的有限元模型，构建胫骨逆行髓内钉、外置接骨板固定模型及骨痂模型并根据骨折的固定原则进行装配。使用ANSYS软件进行有限元分析，比较骨折愈合不同时期时逆行髓内钉及外置接骨板2种固定方式的骨折端位移、胫骨应力遮挡、骨痂应力、胫骨及固定装置应力分布情况。结果与结论：(1)胫骨骨折端相对位移随着骨折愈合的进行逐渐减小，在术后3个月后位移明显减少；术后0,1个月，外置接骨板组的垂直位移及总位移均大于逆行髓内钉组，2种固定方式的Z轴位移(水平内外侧位移)均较X、Y轴位移明显，且接骨板模型的Z轴位移差异最明显；2种固定方式的Z轴位移最大位置均位于胫骨外侧，位移最小位置均位于胫骨内侧；(2)骨折愈合的应力遮挡率随骨折时间延长而逐渐降低；逆行髓内钉的应力遮...     

锥状点式接触接骨板与普通接骨板的力学性能及对局部血流量影响的比较

为了比较锥状点式接触接骨板与普通接骨板的力学性能及对局部皮质骨微循环的影响,采用材料、尺寸完全一致的模拟骨,分别用两种接骨板固定,进行三点弯曲实验和扭转实验比较二者的力学性能。另用１４只山羊,４只正常对照,１０只行胫骨中段横行截骨后分别用两种接骨板固定。术后３天、２周、４周和９周处死动物,用放射性微球局部血流量测定法评价接骨板下和对侧皮质骨血流量。结果发现：两种接骨板的抗弯能力无显著差异;当转角大于１８时,普通接骨板的抗扭能力要高于锥状点式接触接骨板。普通接骨板板下皮质骨持续缺血,而锥状点式接触接骨板板下皮质骨血循环明显好于普通接骨板组,术后２周、４周、９周时分别是后者的２．５倍、９．９倍和２．８倍。接骨板对侧皮质骨缺血是短暂的,术后２周就已恢复。因此,尽管锥状点式接触接骨板的抗扭能力稍低于普通接骨板,但它在保护接骨板下血运方面明显优于普通接骨板,因而更有利于骨折愈合。     

EXPERIMENTAL STUDIES OF THE EFFECTS OF PRESTRESS

ＥＸＰＥＲＩＭＥＮＴＡＬＳＴＵＤＩＥＳＯＦＴＨＥＥＦＦＥＣＴＳＯＦＰＲＥＳＴＲＥＳＳｏｎｉｎｔａｃｔＣｈａｎｉｎｅＴｉｂｉａＢｏｎｅＳｔｒｕｃｔｕｒｅＬｉｕＢａｏｗｅｉ，ＬｕＳｈｉｂｉ，ＷａｎｇＪｉｆａｎｇＤｅｐｔ．ｏｆＯｒｔｈｏｐ．ｏｆＧｅｎｅｒａ...     

分体螺旋式人工股骨头置换后应力分析的对比性研究

目的：论证分体螺旋式人工股骨头置换的合理性。是否符合生物力学原理。方法：利用９具新鲜成入股骨标本,用三种不同人工髋置换后进行实验应力分析和比较。结果：证明分体螺旋式人工股骨头在应力分布、界面应力、应力遮挡车、初始微动等生物力学特性上优于珍珠面假体和钢制人工髋。结论：分体螺旋式人工骨头置换后应力分布合理,固定牢固,具有高度稳定性。     

分体螺旋式人工股骨头置换后应力分析的对比性研究

目的：论证分体螺旋式人工股骨头置换的合理性。是否符合生物力学原理。方法：利用９具新鲜成入股骨标本,用三种不同人工髋置换后进行实验应力分析和比较。结果：证明分体螺旋式人工股骨头在应力分布、界面应力、应力遮挡车、初始微动等生物力学特性上优于珍珠面假体和钢制人工髋。结论：分体螺旋式人工骨头置换后应力分布合理,固定牢固,具有高度稳定性。     

Morphological transformation of limb bones with growth

The development of the long limb bones consists of two developmental types, one for the length and the other for the thickness. Although the development of the length is due to the growth of the epiphyseal cartilage, the development of width is due to the addition of bone to the periosteal membranes. Growth of bones is influenced not only by chemical factor, such as hormone or vitamin, but also by physical factor such as electrical or mechanical stresses. Changes in the development of the limb bones caused by mechanical stress were studied. The limb bones, which belonged to a hydrocephalic patient who had been bedridden for 16 years, were measured. The lower limb bones had almost no mechanical stress such as weight or walking, due to his being bedridden for many years. He also could not exercise his upper extremity, hence mechanical stress to the upper limb bones was minimal. The circumference at the mid-shaft of each long bone was shorter than the average circumference of the same age. The thickness was also narrower, suggesting Wolff's law. However, no difference was found in length between the subject and the average. While mechanical stress was a factor that accelerated the thickness of the limb bones, stress did not have much influences on the length of the long limb bones. The length of the right clavicle was longer than that of the left due to the pressure of maintaining the same posture. In an experimental study of tail suspended rats showed that there was no significant difference in the length of hindlimb between the experimental group and control group, though a difference was found in the length of forelimb. The length of forelimb in the experimental group was significantly shorter than the control group due to weight pressure. This result suggests that physical pressure in the longitudinal direction is one of the factors that inhibits the growth of the length of bones and that mechanical stress is important for the morphology and the function of bones. Stress exerts different influence to accelerate or inhibit bones according to the direction.     

动态应力钢板与AO钢板对羊股骨干骨折愈合的影响

背景：目前钢板内固定治疗骨折愈合出现应力遮挡影响骨折愈合。 目的：观察动态应力钢板(CO钢板)与普通应力钢板(AO钢板)治疗羊股骨干骨折愈合的效果。 方法：24只山羊制备股骨干骨折模型,造模后随机分为2组,AO钢板组和CO钢板组分别用AO、CO钢板内固定,分别在1,2,3周取出股骨,常规行X射线与磁共振扫描。 结果与结论：X射线显示1周时,两组钢板骨折断端均未见明显变化,骨折线清晰可见;2周AO钢板组骨折断端无明显变化,骨折线明显,CO钢板组骨折断端骨密度增高,骨折线开始变模糊;3周AO钢板组骨折断端骨密度增加,CO钢板组骨折断端骨密度继续增高,出现云絮状外骨痂。MRI显示1周时,两组钢板骨折断端T1WI呈高信号,T2WI压脂序列上呈低信号,但AO钢板组骨折断端PDIR-TSE呈低信号,CO钢板组呈高信号。2周时两组骨折断端T1WI呈等或高信号,在T2WI压脂序列上呈等或低信号,AO钢板组PDIR-TSE呈低信号,CO钢板组呈高信号。3周AO钢板组可见骨折线明显,骨折断端在T1WI呈等或低信号,在T2WI压脂序列上呈等低信号,PDIR-TSE呈低信号;CO钢板组骨折断端可见骨折线模糊,骨折断段在T1WI上呈等或高信号,在T2WI压脂序列上呈等或低信号,PDIR-TSE呈等或高信号。提示CO钢板组骨折断端的血液循环、骨痂含量均优于AO钢板组骨折断端。     

Assessment of Carbon Fibre Composite Fracture Fixation Plate Using Finite Element Analysis

In the internal fixation of fractured bone by means of bone-plates fastened to the bone on its tensile surface, an on-going concern has been the excessive stress shielding of the bone by the excessively-stiff stainless-steel plate. The compressive stress shielding at the fracture-interface immediately after fracture-fixation delays callus formation and bone healing. Likewise, the tensile stress shielding in the layer of bone underneath the plate can cause osteoporosis and decrease in tensile strength of this layer.In this study a novel forearm internal fracture fixation plate made from short carbon fibre reinforced plastic (CFRP) was used in an attempt to address the problem. Accordingly, it has been possible to analyse the stress distribution in the composite plates using finite-element modelling.A three-dimensional, quarter-symmetric finite element model was generated for the plate system. The stress state in the underlying bone was examined for several loading conditions. Based on the analytical results the composite plate system is likely to reduce stress-shielding effects at the fracture site when subjected to bending and torsional loads. The design of the plate was further optimised by reducing the width around the innermost holes.     

Effects of the bone-plate material and the presence of a gap between the fractured bone and plate on the predicted stresses at the fractured bone

In the present study, 3D finite element models for fractured bones with function-graded (FG) bone-plates and traditional bone-plates made of stainless steel (SS) or titanium (Ti) alloy are generated using the ABAOUS code. The predicted Von Mises stresses at the fracture site and underlying bone-plate are examined at different healing stages. The effects on the predicted Von Mises stresses at the fracture site of the presence of a gap between the plate and fractured bone are also studied. Based on the analytical results, it is found that the stress shielding at the fracture site at the fully healed stages decreases when using FG bone-plates compared to Ti alloy or SS bone-plates. In the initial healing stages, the Von Mises stresses at the fracture site increase (stress shielding decreases) by 17% and 11% when using FG bone-plates as compared to SS bone-plates for contacted and non-contacted bone-plate system, respectively. The significant effects of using an FG bone-plate with a gap on the resultant Von Mises stresses on the bone underneath the plate and on the bone stress shielding should be taken into consideration during fractured bone fixation.     

ATMFS对犬骨盆弓状线骨折愈合及骨钙蛋白和骨唾液酸蛋白表达的影响

目的探索骨盆髋臼三维记忆内固定系统(acetabular tridimensional memory fixation system,ATMFS)对犬弓状线骨折愈合及骨钙蛋白和骨唾液酸蛋白表达的影响。方法选用15只成年杂种家犬,双侧髋臼臼顶上方1.5cm处横形截骨,分别采用ATMFS前柱固定器和6孔重建钢板内固定,于术后2、4、6、8、12周行影像学检查、大体观察、骨钙蛋白及骨唾液酸蛋白原位杂交、骨钙蛋白实时定量PCR(RT-PCR)检测,评价骨盆弓状线的骨愈合特征及骨钙蛋白和骨唾液酸蛋白的表达特征。结果 ATMFS侧骨折端无凌乱骨痂,骨折愈合时间明显快于钢板侧。双侧骨折端组织中骨钙蛋白和骨唾液酸蛋白表达与正常比均明显增强。术后4～8周,ATMFS侧骨钙蛋白和骨唾液酸蛋白表达量明显大于钢板侧,两侧比较具有显著性差异(P0.05),其中术后6周双侧差异最为显著(P0.01)。结论 ATMFS固定后于骨折端产生的持续顺应生理力线的压应力能够刺激骨钙蛋白及骨唾液酸蛋白的表达,从而促进骨折早期愈合。