基于快速生长期大鼠骨生长与重建适应模型的数字量化研究(英文)

Quantitative study of bone growth and remodeling adaptation model in rapid-growing rats

背景:目前骨重建生物模型研究通常运用有限元分析同计算机技术相结合的方法对骨量或骨结构的变化进行模拟和预测。因此,模型不是处在真实的力学环境中,而是在生理限定应力的范围内进行模拟,通过各种数值方法进行试算。目的:将动物实验、数学表达式中未知参数的反演识别和计算机仿真技术相结合,建立数值量化的骨生长与重建适应生物模型,观察应力环境对快速生长期大鼠股骨生长与重建的影响,设计、时间及地点:对比观察实验,实验于2002-10在大连医科大学动物实验中心完成。材料:6周龄雌性SpragueDawley大鼠60只。法国DMS公司Challenger双能X线骨密度仪,德国西门子公司sensation16CT机。方法:60只大鼠随机分为2组:正常对照组15只,不做任何处置;实验组45只由臀部切断其右侧坐骨神经,致使其右后肢瘫痪。其中左后肢承受多于正常状态下的负重为实验组中的过载组,右后肢基本不承受任何负重为实验组中的废用组。实验期为8周。每周提取的大鼠股骨近端骨密度数值,反演骨生长方程中的未知参数B和K,根据股骨的CT截面信息,重塑了三维几何模型。主要观察指标:大鼠体质量、股骨近端骨密度变化;反演骨生长方程中的未知参数B和K变化。结果:实验期内,实验组和对照组大鼠体质量随时间增长呈递增趋势,对照组和过载组股骨近端骨密度随时间增长呈递增趋势,而废用组骨密度在5周后呈下降趋势。从反演结果和处理后的数据上看,骨生长系数B随时间的变化而迅速变小,第10周时基本接近于零。生长因子K随时间的变化而迅速增加,5～10周内增长减缓,10周以后接近水平线。说明骨的快速生长期已经结束,骨的重建和吸收进入了一个平衡期。结论:实验提出的骨重建适应模型不仅能够数值模拟大鼠快速生长期股骨骨密度变化和外界刺激的关系,而且能够预测大鼠整个生命周期中在不同应力环境下股骨的生长趋势。

BACKGROUND： At present, bone remodeling biological model study usually applys finite element method combing with computer technique to simulate and predict bone quantity or bone structure. In this study the author integrate inversion method with animal experiment to establish a quantification bone remodeling biological model of in vivo bone tissue in real stress environment. OBJECTIVE： To set up a quantification biological model of bone growth and remodeling adaptation, which integrates animal experiments, parameter inversion identification of mathematical functions, and technique of computer simulation, DESIGN, TIME AND SETTING： The experiment was accomplished in Animal Experiment Center of Dalian Medical University in October 2002. MATERIALS： 60 female Sprague Dawley mice of 6-week old were used in this study. Challenger double-energy X ray bone density device was provided from DMS Company, France. Sensation 16 CT machine was provided from Germany Siemens Company. METHODS： 60 mice were randomly divided into two groups： 15 animals were in normal control groups, 45 in experiment groups. By designing a new animal experiment, we investigate the effects of stress environments on bone growth and remodeling of rapid growing rats and gather the bone mineral density （BMD） of proximal femur in the same interval for the unknown parameters （B and K） inversion of bone growth and remodeling equation to create the femur three-dimension geometrical model based on CT images. MAIN OUTCOMING MEASURES： Body weight of animal, bone density and CT imagine of proximal femur. RESULTS： Body mass in the experiment group and control group was increased with the rat growing; BMD in the control group and overloading group was also increased with the rat growing; but BMD in the unloading group was decreased in the fifth week. Inversion and experimental data showed that parameter B was rapidly decreased as compared to time, and it was closed to zero in the 10th week. Parameter K was rapidly increased as compared to time, and it was gradually increased from the 5th to the 10th weeks, moreover, it was closed to the horizontal line after 10 weeks. This predicted that rapid growth was over, and bone reconstitution and absorption came into another balance cycle. CONCLUSION： The thought and method used in the model creating in this paper provide clue and reference to establish human model of bone growth and remodeling.