中国修复重建外科杂志

中国修复重建外科杂志

股骨头缺血性坏死新月征的形成机制

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【摘 要】 目的 对发生股骨头缺血性坏死出现X 线片上“新月征”股骨头的结构改变及与所受应力的对应关系
进行研究,探讨“新月征”的形成机制。 方法 收集1998 年3 月- 2003 年4 月全髋关节置换术前X 线片显示有“新月征”
的股骨头16 例18 髋,进行大体和冠状位断面观察。应用有效压应力原理和应力集中理论对发生在缺血性坏死股骨头上
的结构改变原因进行解释和说明。 结果 松质骨内的骨小梁形成三维立体交互连接的网格结构,孔隙率50% ~ 90%,
髓内压20 ~ 30 mmHg。股骨头内松质骨的构造符合多孔介质的定义,是一种多孔介质。松质骨的变形机制与多孔介质
材料变形机制相同。软骨下骨板与松质骨间的断面结构改变使应力易在二者交界处集中。有效压应力原理和应力集中理
论可对发生在缺血坏死股骨头上的一些现象及彼此之间的关系进行明确的解释和说明。 结论 导致“新月征”骨折线
正发生在软骨下骨板下的原因是由于在坏死灶外侧软骨下骨板局灶性被吸收发生后,软骨下骨板与未被修复坏死松质骨
交界处发生应力集中,集中的应力导致骨折线正位于软骨下骨板下,施加在未被修复坏死松质骨上增加的有效压应力引
起未被修复坏死松质骨的体积减小,从而导致新月形空腔在软骨下骨板下形成,新月形空腔在X 线片上显示出“新月 征”。

【Abstract】 Objective To investigate corresponding relation between structure change of the femoral head with
“crescent sign” and stress exerted on the avascular necrosis of femoral head, to explore the mechanism of the “crescent sign” formation. Methods From March 1998 to April 2003, the femoral heads of 18 hips in 16 cases having osteonecrosis and “crescent sign” in X-ray film before total hi p arthroplasty, were collected. General and coronal section plane morphology of the femoral heads were observed. The princi ple of effective stress and stress concentration theory were used to explain the phenomena and structure changes in osteonecrosis of the femoral head. Results Cancellous bone existed as a threedimensional,interconnected network of trabeculae rods and plates, with 50%-90% of porosity and 20-30 mmHg bone marrow pressure. According to the definition of porous media, bones especially cancellous bone was a kind of sol id and l iquid two phases porous media. Cross-sectional structure changes in the junction between subchondral plate and cancellous were the place where stress concentrated. The principle of effective stress and stress concentration theory could explain the phenomena and their relationship that occurred in avascular necrosis of the femoral head. Conclusion The “crescent sign” starts in an area of very focal resorption in the subchondral plate laterally and peripherally. The focal resorption in the subchondral plate breaks the continuity of subchondral plate and causes stress concentration in the resorption region. The concentrated stress accumulates in the junction between subchondral plate and unrepaired necrotic cancellous bone brings on the fracture right below the subchondral plate. The focal resorption of the subchondral plate also provides a pathway for the pore water in the unrepaired necrotic bone skeleton to outflow, therefore cause effective stress increase and unrepaired necrotic bone skeleton be compacted by increased effective stress appl ied on unrepaired necrotic cancellous bone skeleton, and results in the volume decrease of unrepaired necrotic cancellous bone and the formation of cavum below the subchondral plate. The cavum shows “crescent sign” in the X-ray film.

关键词: 股骨头缺血性坏死; 新月征; 多孔介质; 有效压应力

Key words: Avascular necrosis of femoral head; Crescent sign; Porous media; Effective stress

引用本文: 张念非,祈生文,柴建峰. 股骨头缺血性坏死新月征的形成机制. 中国修复重建外科杂志, 2008, 22(3): 303-306. doi: 复制

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