Ultrastructure observation of experimental osteoporotic fracture healing / 中华骨科杂志

ABSTRACT

Objective To observe the ultrastructural alteration and healing characteristics of osteoporotic fracture, and to elucidate its cellular mode of healing. Methods Eighty female SD rats of 8 months old, which had the weight of 290 to 340 g, were randomized into two groups of 40 each the osteoporotic fracture model(OPFM) and the common fracture model(CFM). After anesthesia, the bilateral posterior transperitoneal approach was performed in the OPFM group and the bilateral ovaries were removed; and in the CFM group, only the sham operations were performed. Three months later, the fracture of femoral middle shaft were created and fixed with a Kirschner pin through medullary cavity. The callus of each rat was examined by transmission electron microscopy(TEM) and scanning electron microscopy(SEM) in 5 days and 1, 2, 4, 6, 8, 12 and 16 weeks postoperatively. Results TEM showed that the number of chondrocyte in OPFM group was greater, but function was lower than that of CFM group. Volume of collagen secreted by the chondrocyte was less and arranged irregularly during the fracture healing period in OPFM group. Number and function of osteoblasts in OPFM group were lower than that of CFM group. Extracellular collagen was disordered and sparse, but function of osteoclasts in OPFM group was more active than that of CFM group. The SEM showed that the collagen in callus of CFM group was dense and arranged in good order or pyknotic. Conclusion The fracture healing of the osteoporotic fractures is due to the decrease of the osteoblastic formation and the increase of the osteoclastic resorption as well as the poor bony healing quality.