The introduction of isobutyl 2-cyanoacrylate into artificially created defects in rat tibiae resulted in an intense inflammatory response, bone destruction and retardation of normal repair mechanisms.
The introduction of isobutyl 2-cyanoacrylate into artificially created defects in rat tibiae resulted in an intense inflammatory response, bone destruction and retardation of normal repair mechanisms.
We have developed a bioactive bone cement using CaO-SiO2-P2O5-CaF2 glass powders and ammonium phosphate solution, and investigated its histological and mechanical characteristics in vivo. A bone defect was drilled in ...
详细信息
We have developed a bioactive bone cement using CaO-SiO2-P2O5-CaF2 glass powders and ammonium phosphate solution, and investigated its histological and mechanical characteristics in vivo. A bone defect was drilled in the proximal metaphysis of the rat tibia and filled with the bioactive bone cement in paste form or polymethylmethacrylate (PMMA) bone cement in the dough state. The cements were allowed to harden in situ. Histological examination demonstrated direct bonding between the new cement and bone by 4 weeks. The bioactive bone cement did not degrade up to 24 weeks postimplantation. The inflammatory reaction to the bioactive bone cement was less intense than the reaction induced by PMMA. Changes in the mechanical properties of the cement in vivo were studied by implanting hardened cylindrical specimens of both types of cement into the hindlimb muscles of rats for 12 weeks. The compressive strength of the bioactive cement increased significantly after implantation, and reached 68 MPa in 1 week and 73 MPa in 4 weeks. These values were comparable to those of PMMA, and were maintained up to 12 weeks after implantation. This bioactive bone cement hardens in situ within a few minutes with negligible rise of temperature and can be easily handled as a paste for filling bone cavities of different shapes. In addition, this cement has good osteoconductive and bone bonding potential and fairly high mechanical strength. Therefore, this new cement could be used both as a bioactive bone cement and bone defect filler.
After observation of detailed structural evidence for the origin of birds from dinosaurs(1), and in light of evidence that dinosaur bone tissue resembles the histology in mammals(2), the histology of bone has become o...
详细信息
After observation of detailed structural evidence for the origin of birds from dinosaurs(1), and in light of evidence that dinosaur bone tissue resembles the histology in mammals(2), the histology of bone has become one of the focal points in discussions of the physiology of dinosaurs and Mesozoic birds(3-10). Most of this microstructural information has focused on features related to the vascular organization and the amount of remodelled bone around vascular canals. However, the finer structures have received less attention, although differences in such structures have been observed among modern vertebrates(10,11). Here we present evidence that canaliculi-the submicrometre-sized channels that interconnect bone cells and vascular canals-and the collagen fibre bundles in bone are differently organized among certain dinosaur lineages. Ornithomimid dinosaurs(12) are more like birds than mammals in these features. In canalicular structure, and to some extent in fibre bundle arrangement, ornithischian dinosaurs are more like mammals. These differences in both canalicular and lamellar structure are probably linked to differences in the process and rate(13) of bone formation.
作者：
Cowin, SCCUNY City Coll
Ctr Biomed Engn Sch Engn New York NY 10031 USA CUNY City Coll
Dept Mech Engn Sch Engn New York NY 10031 USA CUNY
Grad Sch New York NY 10031 USA
Poroelasticity is a well-developed theory for the interaction of fluid and solid phases of a fluid-saturated porous medium. It is widely used in geomechanics and has been applied to bone by many authors in the last 30...
详细信息
Poroelasticity is a well-developed theory for the interaction of fluid and solid phases of a fluid-saturated porous medium. It is widely used in geomechanics and has been applied to bone by many authors in the last 30 years. The purpose of this work is, first, to review the literature related to the application of poroelasticity to the interstitial bone fluid and, second, to describe the specific physical and modeling considerations that establish poroelasticity as an effective and useful model for deformation-driven bone fluid movement in bone tissue. The application of poroelasticity to bone differs from its application to soft tissues in two important ways. First, the deformations of bone are small while those of soft tissues are generally large. Second, the bulk modulus of the mineralized bone matrix is about six times stiffer than that of the fluid in the pores while the bulk moduli of the soft tissue matrix and the pore water are almost the same. Poroelasticity and electrokinetics can be used to explain strain-generated potentials in wet bone. It is noted that strain-generated potentials can be used as an effective tool in the experimental study of local bone fluid flow, and that the knowledge of this technique will contribute to the answers of a number of questions concerning bone mineralization, osteocyte nutrition and the bone mechanosensory system. (C) 1999 Elsevier Science Ltd. All rights reserved.
暂无评论