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

Wenzhi ZHAO; Yingxi LIU; Jun ZHANG; Lu ZHANG

ABSTRACT

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 l6 CT machine was provided from Germany Siemens Company.

METHODS:

60 mice were randomly divided into two groups i 5 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.