OSTEOCLASTIC RESORPTION OF HAVERSIAN SYSTEMS IN CORTICAL BONE OF FEMORAL NECK IN AGED WOMEN A SCANNING ELECTRON MICROSCOPIC STUDY

摘要

Objective. To reveal the sequence of events of osteoclastic resorption taking place in the cortical bone of the femoral neck in aged women. Material and Methods. The cross sections of cortical bones of the femoral neck from 7 aged women who underwent endoprosthetic replacement for intracapsular hip fracture, were processed and subjected to scanning electron microscopic observation. Results. The cortical bone sections revealed enlargement of the Haversian canals. On the inner linings of the enlarged canals many oval resorption lacunae could be found, reflecting osteoclastic resorption of the Haversian systems. The osteoclastic resorption with subsequent enlargement of the Haversian canals into round or oval cavities took place first over the inner portions of the cortical sections, thereby rendering these areas porotic (cancellization). These processes of the Haversian systems and canals then gradually emerged over the central and eventually over the outer areas of the cortical bone, and the entire cortical bone became porotic. Meanwhile, the inner porotic portion of the cortex turned into trabeculae (trabecularization) and became gradually re-sorbed, resulting in thinning of the medial cortex. Conclusions. Cortical cancellization, trabecularization and thinning compromised the material strength of the femoral neck so that fracture would ensue even with trivial in- jury.