| With the increase in human life expectancy across the globe, the population aging poses new threats to human being's welfare, the Osteoporosis (OP) and the bone fracture induced by OP ranks sixth among the common diseases, severely threatening the health of the old and middle-aged people. The increase in population base and the speeding up of aging combine to make the OP a serious problem plaguing the old and middle-aged people in China. In particular, the osteoporosis occurring after menopause and the bone fracture from OP have constituted the main threats to the old and middle-aged women in China. Concerning OP, an extensive and in-depth research needs to be carried out to explore the possible mechanism and the developing process, thus making it possible to prevent OP actively, to relieve or remove the pain from OP, and to treat the OP effectively which has brought much pain and substantial economic burden to patients. The paper consists of two parts. The first part deals with the issue of simulating the osteoporosis process on three respects: the mechanical factor, biological factor, and the mechanical-biological factor, thus making us being informed of the level of OP, and making possible the active prevention and effective treatment towards OP. The second part conducts an animal experimental study on OP treated by means of high-frequency and low-magnitude vibration to seek a preventing and treating method characterized by no drug use and no invasiveness, facing the situation that the primary methods for treating OP are drug therapies assisted by nutrition therapies and exercise therapies which usually tends to induce a series of problems such as the drug-resistance of the body, gastrointestinal stimulation, and kidney stones.At present it has been the focus of research to conduct quantitative numerical modeling by computer based on the outcomes of some experiments. Part one of the dissertation puts forward a quantitative computational model with time course involved of the developing process of OP concerning the interior of cortical bone, cancellous bone, and the cortical endometrial; explores the application of the new quantitative computation model into the simulation of the effect of the OP caused by disuse as well as peak bone mass on the OP process. And only the contributions of mechanical factor to the development of osteoporosis were discussed.Based on the function of adaptive bone and the theory of mechanical control system, three computational models describing the OP process and indicating the time course were put forward with regard to the three places of the interior of cortical bone, cancellous bone, and the cortical endometrial respectively, in accordance with the physiological process of bone remodeling; the OP from disuse was simulated as well. The three models were applied to discuss the effect of PBM (peak bone mass) change and the threshold change of the bone remodeling on the OP process of the cancellous bone, with the outcome very similar to the real physiological process. The state variables, parameters and control equation in the model are in capable of describe the mechanical and biological process of disuse OP.The simulation of the proximal femur OP based on the three models was presented preliminarily, simulating the OP process at different age levels and various disuse extent, with the results approaching fairly the actually measured data in documents. The disuse OP simulation about the cortical bone endometrial was conducted from the three perspectives of the mechanical factor, the biological factor, and the mechanical-billogical factor, with the simulation result from the perspective of the mechanical-billogical factor more in line with the real physiological process. The establishment of the three models enabled the simulation of osteoporosis to undergo the transformation from micro to macro and the transformation from the point level to the structure level, thus providing both the theoretical basis and computational method for the research on osteoporosis, and serving as good guidance for clinical practice.In the second part, based on the pre-tests at the early stage, the animal experiment was formulated, in which the 8-week high-frequency low-magnitude vibration with f = 32Hz and a = 0.3g was conducted on the rats, and the comparison between the continuous vibration and the intermittent vibration was made.For the multiple primary OP, the ovariectomized rats model (simulated the I type OP ) and the tail-suspended rats model (simulated theâ…¡type OP ) were established, with the f = 32Hz, a = 0.3g continuous vibration and the intermittent vibration imposed on the ovariectomized rats model, and only the f = 32Hz, a = 0.3g continuous vibration on the tail-suspended rats model due to the experimental condition and other reasons .From the 8-week experiment, the following observations were obtained:(1)Over the 8 weeks, no significant difference was recorded and obtained among all the groups concerning the life habits, with activity amount, diet, and water basically the same. No significant difference was recorded for the skin color among all the groups. All rats survived.(2) The tibiae of rats were divided into three parts; the shafts of the tibia were made into 5mm-high cylinders, as the compact bone specimens of the compression and breakage experiment with their elastic modulus (E) measured. It was discovered that the mechanical capability of the vibrated groups got enhanced by different degrees. In particular, the compact bones'capability improved significantly in the conditions of O+V (Ovariectomized) and O+IV (Ovariectomized +Intermittent) as compared with in the condition of O (Ovariectomized). While, no significant difference was found between that of the O+IV group and that of the O+V group.A 3mm-high cylinder was taken by abrading the spongy bone of the proximal tibia, as the spongy bone specimen of the compression and breakage test, with its elastic modulus measured. It was discovered that the elastic modulus (E) of the spongy bone improved by different degrees in the group of O+V,S+V, and O+IV as compared with other groups, in particular, the elastic modulus in the O+IV group got enhanced more significantly than that in the O+V group. It is indicated that through the 8-week vibration especially the intermittent virbration on the spongy bone, the anti-compression and anti-breakage ability of the tibia of rats was heightened. In other words, the quality of the tibia got improved.(3) The dynamic measurement of the tetracycline calibration was carried out on the rats to produce the bone mineralization apposition rate (MAR) of all the groups. The MAR value of group O was the highest, the MAR value of group S was the next highest, and the MAR value of group S+V was the lowest. It is indicated that the OP has got lessened significantly after 8 weeks'vibration with f = 32Hz, a = 0.3g. It is testified that the vibration method could prevent and treat OP effectively.(4) The static measurement was carried out on the rats to get the trabecular area percent (%Tb.Ar), trabecular thickness (Tb.Th), trabecular number (Tb.N), trabecular separation (Tb.Sp). The results indicated there existed significant difference among all groups of rats (P<0.05).In terms of the %Tb.Ar, the O+V group was 0.45% and 165.62% higher than the SHAM group and the O group separately. The S+V group (Suspension+Vibration) was 93.10% and 64.72% higher than the S (Suspend) group and the S+L (Suspension+Lode) group respectively. The O + IV group was 5.7% and 119.19% higher than the SH group and the O group separately. But there was no significant difference between the %Tb.Ar of the O + IV group and that of the O group (P>0.05). It indicated that after 8 weeks vibration, the bone mass of all groups increased significantly, while no significant difference was found between the effect of the intermittent vibration and that of the continuous vibration.In terms of the Tb.Th, the O+V group was 3.46% and 12.51% higher than the SH group and the O group separately. The S+V group was 15.88% and 5.2% higher than the S group and the S+L group respectively. The O + IV group was 11.78%, 21.42% and 7.92% higher than the SH group, the O group and the O+V group respectively. The results indicated that the trabecular structure of the O+V group, the O + IV group and the S+V group were improved significantly after 8 weeks'vibration, with the intermittent vibration more effective.In term of the Tb.N, the O+V group was 49.58% and 193.37% higher than the SH group and the O group respectively. The S+V group was 118.99% and 29.43% higher than the S group and the S+L group separately. The O + IV group was 52.39%,198.9% and 1.88% higher than the SH group, the O group and the O+V group separately. The results indicated that the trabecular structure of the O+V group, the O + IV group and the S+V group were improved significantly after 8 weeks'vibration, with the effect of the intermittent vibration slightly better.In terms of the Tb.Sp, the O+V group was 10% and 49.65% lower than the SHAM group and the O group respectively. The S+V group was 39.1% and 29.71% lower than the S group and the S+L group separately. The O + IV group was 12.67%,51.14% and 2.84% higher than the SH group, the O group and the O+V group separately. The results indicated that the trabecular structure of the O+V group, the O + IV group and the S+V group were improved significantly after 8 weeks'vibration, with the effect of the intermittent vibration slightly better.From the above four respects, it was indicated that after 8 weeks'vibration, for the rats from all the groups, the %Tb.Ar got widened, the Tb.Th got thickened and the Tb.N got heightened by different degrees. These mean that the structure of the vibrated bone trabecular gets improved in terms of the fine structure.Due to limited experimental condition and time, the effect of the intermittent vibration and that of the continuous vibration do not differ significantly. Future research shall lengthen should extend the experimental time and the intermittent frequency to testify to their difference.Through the observation of the physiological responses and life habits, through the measurement of the bone's mechanical properties and the bone histomorphometric, it was shown that the 8 weeks'vibration with f = 32Hz, a = 0.3g could not only enhance the elastic modulus (E) of the compact bone and the spongy bone of the tibia, but could also increase the area, the thickness, and the number of the trabecula significantly, with the effect of the intermittent vibration was slightly better than that of the continuous vibration. The results showed that the high-frequency low-magnitude vibration with f = 32Hz, a = 0.3gis capable of enhancing the mechanical properties of the tibia, improving the fine structure of the bone, with the effect of the intermittent vibration possibly better. In other words, the f = 32Hz, a = 0.3g vibration was conducive to the treatment of OP with the effect of the intermittent vibration possibly better.
|
PDF Full Text Request