老年人髋部好发骨折的超微结构根据

Ultrastructural Evidences for Vulnerability of Hip Region to Fracture in Aged People

目的：探索老年人髋部好发骨折而股骨头不易骨折的原因．方法：通过扫描电镜及透射电镜对２１例股骨头及颈部（１４例进行人工股骨头置换的股骨颈囊内骨折病例及７例死于脑外伤的青年人）作超微结构水平的观察．结果：（１）在老年人股骨上端有三种形式的骨吸收，即松质骨小梁的破骨细胞性骨吸收、松质骨小梁的骨细胞性骨吸收，以及皮骨质哈氏系统的破骨细胞性骨吸收．（２）在青年人中，骨小梁所组成的拱桥结构在头部为圆形或近似圆形，在头、颈交界部为卵圆形，在颈部为狭长卵圆形．在老年人中虽发生骨吸收，各部位的骨小梁拱桥结构基本维持原来的形态特征．结论：（１）髋部好发骨折是由于各种形式的骨吸收降低骨的结构强度所引起．（２）股骨头因其圆形及近似圆形的骨小梁拱桥结构能很好承受各种方向的外来暴力而不易发生骨折，尽管骨小梁有骨吸收．头。

Aim: To probe ultrastructually into why hip region was the predilected site of fracture in aged people, yet with the femoral head exempted. Methods: Twentyone upper femoral ends, including 14 specimens collected from aged people undergoing endoprosthetic replacement for intracapsular fracture of femoral neck and 7 from young adults died of brain injury, were subjected to transmission electron microscopic and scanning electron microscopic observation. Results: In the upper femoral ends of the aged existed three types of bone resorption, viz., osteoclastic resorption and osteocytic resorption of trabeculae of the cancellous bone and osteoclastic resorption of Haversian systems of the cortical bone. In the young adults the arch structures constituted by the trabeculae of the femoral head showed round or roundish configuration, while those of femoral headneck junction revealed oval profile and those of femoral neck exhibited narrow oval outline. In aged people, the morphological characteristics of the trabecular arch structures remained despite overtl one resorptions. Conclusion: Vulnerability of hip region to fracture in aged people is due to a decline in structural strength of bone tissues resulted from osteoclastic and osteocytic resorption. The round and roundish trabecular arch structures of the femoral head can bear the external forces from various directions so effectively that no fracture will take place here, while the oval and narrow oval bones of the headneck junction and the neck region fail to stand the horizontal external forces, thereby leading to fracture easily.