Smith G K, LaFond E, Heyman S J, Cofone M A, Gregor T P
Department of Clinical Studies, School of Veterinary Medicine, University of Pennsylvania, Philadelphia 19104, USA.
Am J Vet Res. 1997 Oct;58(10):1078-82.
To investigate the in vitro load/displacement characteristics of the hip joints in dogs as a function of joint position.
10 hip joints from 5 healthy dogs.
A material test system was used to generate load/displacement curves for each joint. Joints were mounted in a custom-designed jig that held the joint in fixed anatomic orientations while plotting displacement and corresponding applied loads. All hips were cycled between 40 N of compression and 80 N of distraction. Each hip was tested at 10 degrees increments from 30 degrees flexion to 70 degrees extension.
When the hips were in a neutral orientation (approximately a standing position), load/displacement curves were characteristically sigmoidal (tri-phasic), indicating that, in this position, displacement was not highly dependent on load. The curves had a central low-stiffness region in which most of the lateral displacement took place. In contrast, when hips were positioned at the extremes of flexion and extension, this central, low-stiffness region was less distinct, and load/displacement curves were more linear, indicating a proportional relation between load and displacement. The load/displacement curve of 1 hip joint in the study deviated markedly from the others in a pattern consistent with cavitation of the synovial fluid.
When the hip joint is positioned in a neutral position, load-displacement behavior is sigmoidal, whereas when the hip joint is in an extended position, load/displacement behavior is more linear.
Establishing load/displacement behavior of the hip joints in dogs was an important exercise in establishing the position for and estimating the repeatability of a clinical stress-radiographic method for quantitating joint laxity in dogs.
研究犬髋关节在体外的负荷/位移特性与关节位置的关系。
来自5只健康犬的10个髋关节。
使用材料测试系统为每个关节生成负荷/位移曲线。关节安装在定制设计的夹具中，该夹具将关节保持在固定的解剖学方位，同时绘制位移和相应的施加负荷。所有髋关节在40 N的压缩力和80 N的牵张力之间循环。每个髋关节在从30度屈曲到70度伸展的过程中以10度的增量进行测试。
当髋关节处于中立方位（近似站立位）时，负荷/位移曲线呈典型的S形（三相），表明在此位置，位移高度不依赖于负荷。曲线有一个中央低刚度区域，大部分侧向位移发生在此区域。相比之下，当髋关节处于屈曲和伸展的极端位置时，这个中央低刚度区域不太明显，负荷/位移曲线更呈线性，表明负荷与位移之间存在比例关系。研究中的1个髋关节的负荷/位移曲线与其他曲线明显不同，其模式与滑液的空化一致。
当髋关节处于中立位置时，负荷-位移行为呈S形，而当髋关节处于伸展位置时，负荷/位移行为更呈线性。
确定犬髋关节的负荷/位移行为对于确定一种用于定量犬关节松弛度的临床应力放射学方法的位置和估计其可重复性是一项重要的工作。
