SCANNING ELECTRON-MICROSCOPY OF HUMAN LUMBAR VERTEBRAL TRABECULAR BONE SURFACES

Trabecular bone from fourth lumbar vertebral bodies of 30 autopsy subjects (18 male and 12 females, 30-91 years of age) was investigated using surface mode scanning electron microscopy. In the younger individuals, proper coupling of formation and resorption appeared to have maintained both the bone mass and the shape and structural integrity of the trabecular elements. In elderly individuals, including osteoporotics, irregularities and uncoupling of these activities brought about a loss of bone and a disruption of trabecular structure. Distinct resorption patterns (lateral and vertical) are responsible for trabecular thinning and removal of structural elements. Irregularities in the formative process in old age may account for the compensatory thickening and changes in shape and texture of trabecular elements. The mechanisms involved in the occurrence of microfractures and the fate of disconnected elements were also identified. An increased proportion of arrested mineralizing fronts is found in older individuals and in frank osteoporotics. Resorption may occur through osteoid and arrested mineralizing fronts, as well as through resting, fully mineralized surfaces.