应变理论在骨折愈合中的临床应用PPT通用课件

1、应变理论在骨折愈合中的临床应用一点粗浅的了解2011-03-30骨折愈合的分型应变的概念基于Perren应变理论的一些AO理念附：微动促进骨折愈合的一项研究要点Fracture healing can be divided into two types:primary or direct healing by internal remodeling; secondary or indirect healing by callus formation 骨折愈合分为2种类型通过内塑形的一期或直接愈合通过骨痂形成的二期或间接愈合直接愈合occurs only with absolute stabil

2、ity and is a biological process of osteonal bone remodeling 仅发生在绝对稳定固定时，它是骨单位重建的生物过程绝对稳定使骨折部位的修复组织在生理负荷下的应变完全消除将应变减少到临界值以下可以减少骨痂形成的刺激，使骨折的愈合没有出现肉眼可见的骨痂间接愈合occurs with relative stability (flexible fixation methods). It is very similar to the process of embryological bone development and includes both

3、 intramembraneous and endochondral bone formation. In diaphyseal fractures, it is characterized by the formation of callus. 发生于相对稳定固定时（弹性固定方法），包括膜内成骨和软骨成骨除了加压技术外，所有的固定方法均可视为弹性固定，提供相对稳定性。其特点是骨痂形成Bone healing can be divided into four stages:inflammation; soft callus formation; hard callus formation; r

4、emodeling. 骨折间接愈合的四个阶段炎性期软骨痂形成期硬骨痂形成期重塑形期Interfragmentary movement stimulates the formation of a callus and accelerates healing 骨痂形成需要一定程度的力学刺激骨折块之间的相对活动可刺激骨痂的形成，加速骨折的愈合Perrens strain theoryThe manner in which mechanical factors influence fracture healing is explained by Perrens strain theory.Perren

5、 SM, Cordey J (1980) The concept of interfragmentary strain. Berlin Heidelberg New York: Springer-Verlag.Perren应变理论解释了机械力学因素对于骨折愈合的影响Perrens strain theory Perren应变理论Motion at the fracture results in deformation producing strain in the granulation tissue at the fracture site.骨折端的活动引起的形变会在骨折端肉芽组织中产生应变

6、Strain-应变Strain is the deformation of a material when a given force is applied. Normal strain is the change in length ( l) in comparison to original length (l)when a given load is applied. Thus, it has no dimensions and is often expressed as a percentage. 在应力作用下，材料在单位长度内发生的形变对材料施加应力后其长度发生的变化没有单位，通常用

7、百分比表示=（L-L。）/L。= L/L组织在功能正常状态下可耐受的变形程度有很大的变化范围完整骨骼的正常应变程度为2%（骨折发生前）肉芽组织的应变能力为100%在早期，当骨痂主要成分为软组织时，骨折端耐受畸形或组织应变的强度要大于后期的骨性骨痂The amount of deformation that a tissue can tolerate and still function varies greatly. Intact bone has a normal strain tolerance of 2% (before it fractures), whereas granulatio

8、n tissue has a strain tolerance of 100%. Bony bridging between the distal and proximal callus can only occur when local strain (ie, deformation) is less than the forming woven bone can tolerate. Thus, hard callus will not bridge a fracture gap when the movement between the fracture ends is too great

9、 Thus, overloading of the fracture with too much interfragmentary movement later in the healing process is not well tolerated只有当局部的应变小于编织骨所能耐受的程度，远近端的骨痂才能发生骨性连接因此，当骨折端的活动过大时，硬骨痂无法桥接骨折端在骨折愈合的后期，过度的负荷使骨折块发生过多的活动不利于骨折的愈合Callus formation will not take place when the strain is too low A low-strain enviro

10、nment will be produced if the fixation device is too stiff, or if the fracture gap is too wide . Delayed healing and nonunion will result但是，当应变过小时骨痂无法形成当固定装置过于坚硬或骨折间隙过宽时，会产生低应变的环境，此时可发生骨折不愈合或延迟愈合根据Perrens strain theorythe strain is the higher the smaller the gap is.The same deforming force produces

11、more strain at the site of a simple fracture than at that of a multifragmentary fracture.骨折间隙越小，应变越大相同的应力作用于简单骨折和粉碎骨折，其中简单骨折产生的应变较大Multifragmentary fractures tolerate more motion between the two main fragments because the overall movement is shared by several fracture planes, which reduces the tissu

12、e strain or deformation at the fracture gap. 粉碎骨折可耐受两个主要骨折块之间有更大范围的活动因为其总的活动被不同的骨折平面所分担，因此减少了骨折间隙中组织的应变A perfectly reduced simple fracture (small gap) stabilized under compression (absolute stability and low strain) heals without external callus (direct healing). 简单骨折（间隙小）解剖复位加压固定（绝对稳定，低应变）后，骨折发生无外骨

13、痂的愈合（直接愈合）A simple fracture (small gap) fixed with a bridging plate (relative stability) is exposed to movement (high strain). Fracture healing is delayed or will not occur at all 简单骨折（间隙小）用桥接钢板（相对稳定）固定后，骨折端的活动导致高应变，骨折愈合延迟甚至不愈合Today there is clinical experience and experimental proof that flexible f

14、ixation can stimulate callus formation, thereby accelerating fracture healing . This can be observed in diaphyseal fractures splinted by intramedullary nails, external fixators, or bridging plates 已有临床和实验室证据表明弹性固定可刺激骨痂的形成，从而促进骨折的愈合骨干骨折后，使用随内钉、外固定架、桥接钢板固定可观察到这一现象In a complex fracture (large gap) fixe

15、d with a bridging plate (relative stability) the strain will be low in spite of movement, and fracture healing will occur with callus formation (indirect bone healing). 复杂骨折（间隙大）用桥接钢板（相对稳定）固定后，骨折端虽有活动，但应变低，骨折发生有骨痂形成的愈合（间接愈合）外部机械刺激对应用弹性外固定固定的骨干截骨模型愈合作用的研究BackgroundIt is generally accepted that small

16、interfragmentary movements (IFMs) yield better bone healing results than larger IFMs ( 1 mm). However, the optimal size of IFM within the l-mm range remains undetermined.ObjectiveThe purpose of this study was to investigate the effect of an externally applied mechanical stimulus on fracture healing

17、under flexible fixation.DesignStimulation of fracture healing under various conditions of interfragmentary movement in an in vivo fracture model on 41 sheepMethodsStandardized transverse osteotomy of 3 mm gap size in the left ovine tibia was fixed with an unilateral external fixator. To perform cont

18、rolled axial micromovement, a custom-designed stimulation module was applied to the fixator rods (Fig. 1). The module was electromechanically driven and controlled by a microprocessor .MethodsThe sheep were divided into four IFM groups of 0.0, 0.2, 0.4 and 0.8 mm and stimulated with this amplitude（振幅） for 1200 cycles per day