A Mechanistic Model For Internal Bone Remodeling In Disuse And Simulation Of Osteoporosis On Cancellous Bone At Meso-structural Level

The structure of bone adapts to its mechanical condition, which is usually called the relationship between loading and growing. The study on bone functional adaptation is not only the basis of biomechanics, but also has greatly theoretical importance and wide application. "A mechanistic model for internal bone remodeling in disuse"put forward BMU's remodeling , which approaches the real physiological process. Cancellous bone is an important part of bone, which is porous, made of an interconnecting framework of trabeculae. The research of functional adaptation of cancellous bone is presently a hot point, which is the important basis of the development of orthopaedics. The research on bone adaptation of cancellous bone has profoundly investigating content, and has important clinical value and healthy significance. Cancellous bone is a central suffer injury part of osteoporosis. Obviously, the simulation of osteoporosis in meso-ostructure of cancellous bone has great investigating content, which is the theoretical basis and computer model of prevention and cure the osteoporosis. As a serious disease over all the world, osteoporosis is threatening the health of human being, which is recognized by more and more people widely. At present , many investigators have done much research on osteoporosis , and most focused on bone physiology and the effects of medicine to the treatment of osteoporosis . Thus biochemical markers of osteoporotic structure were often investigated. There are also many experiments dealing with the occurrence of osteoporosis , but unfortunately little is done about the basic quantitative model . By combining it with FEM the structure of bone can be predicated. The research of this dissertation is quantitative research based on the actual physiology and results of many experiments . The paper investigated the mechanistic model for internal bone remodeling in disuse model, and simulated the osteoporosis in cancellous structure, which integrated with a grant from the National Natural Science Foundation of China "The relationship of mechanical and biological factors of osteoporosis and the computational simulation". Most of works is as follows : 1. Put forward "A mechanistic model for internal bone remodeling in disuse" Scott J.Hazelwood etc (2001) put forward the mechanistic model for internal bone remodeling exhibits different dynamic responses in disuse and in damage which is the newest and most approaches to real biological process of bone remodeling model. To apply it in the simulation of osteoporosis in meso-structure of cancellous bone, we modified it as below: (1) We got rid of the part of "damage computation", because it is not essential in the process of osteoporosis; (2) We introduce "cyc model"to simulation, i.e."one day"is the cycle time in former model, we changed it to cyc(cyc=2.4.8) as the new cycle time. Correspondingly, we changed the parameter in model. At last, we compare the results and data of the two model. We got these results as: the difference of the two model is little, which hardly has influence on the simulation. 2. discuss the effects of different initial strain model and corresponding parameter to results of simulation we discussed many parameters including the bone filling area-Af, the form of elastic model, the refilling period , the resorption period, the reverseperiod. The results indicated that however we changed the parameter of "high strain model", we can't get a result which approached to experiment data, while by using "low strain model", our simulating results is near to the experiment data. So we concluded that "low strain model"is a more ideal model to simulate the process of osteoporosis. 3. simulate the idiopathy osteoporosis—the osteoporosis aroused by ageing and menopause factor combining FEM and the mechanistic model for internal bone remodeling in disuse. As to the simulation of osteoporosis aroused by ageing, we renovated the load in model in every cycle time according to the muscle strength-age curve suggested by Burr DB. The result indicated that load has great effect on simulation. Moreover, we enhanced the MESr by the period of age. The result didn't approach to experimental data greatly. The cause was that we had adopted the "high strain model"as the initial model. We can improve it by using "low strain model"as the initial model to study in the days to come. On the other hand, menopause can make MESr improve 30% and BMU activation frequency increase. We simulated the osteoporosis aroused by menopause from above two sides. The results indicated that MESr improving 30% conduced bone loss increasing more than 10%; the increase of BMU activation frequency didn't work on the simulating results obviously. So we got the conclusion that the improvement of MESr is a more crucial factor to the osteoporosis aroused by menopause. 4. pilot study the prevention and cure of Chinese osteoporosis According to the experiment data of Chinese osteoporosis, we simulated a load-age curve of Chinese conversely. It is very vital to establish scientific and logical exercise project which includes sport mode , sport quantity and sport extent at different phase and at different part to prevent and cure osteoporosis in middle-aged men . And then it provides theoretical basis and the method for computation and analysis . The research in this dissertation was supported by Natural Science...