| Objectives To study the influence of bone mineral density and bone microstructure of the surrounding bone tissue after implantation of mesoporous bioactive glass (MBG) in bone defects of osteoporotic area, the ability of MBG mediated osteogenesis and induction osteogenesis, and the therapeutic effect of MBG implantation in osteoporotic fracture patients.Methods Firstly we made disused osteoporotic models. Left hind limbs of twenty healthy adult new zealand rabbits were fixed with polymer-plaster cast. To test the effect of the models, we measured the bone mineral density (BMD) of bilateral hind femoral condyle and tibial plateau by the site-directed method just before fixation(TO) and after fixation 2 weeks(T1)、4 weeks (T2)、6 weeks(T3).Secondly those 20 adult new zealand rabbits were randomly divided into MBG group and control group(n=10) just after the disused osteoporotic models were prepared successfully.5 mm encapsulated bone defects in the center of left hind femoral condyle were done by electrical drill. MBG was implanted into the defects in MBG group, and nothing was implanted in control group(n=10). Left hind limbs of all rabbits in two groups were still fixed with plaster cast after operation for 4 weeks. The values of BMD of bilateral hind femoral condyle and tibial plateau were measured immediately after operation(T4), and at 2 (T5)、4(T6)、6 (T7)、8 (T8)、10(T9)、12 weeks (T10) after operation (n=10,10,8,6,3,3,3). The results of BMD of different areas were compared by statistical methodology between two groups.X ray of bilateral hind limbs was taken at T4、T7 and T10(n=10,6,3).There were 2、2、3 and 3 rabbits died (sacrificed artificially and died accidentally) at T5、T6、T7 and T10 in two groups. General samples and microstructure examination were done with samples of the left hind femoral condyle (n=2,2,3,3).Result (1) The values of BMD of bilateral hind femoral condyle and tibial plateau at T3 decreased by 0.080g/cm2(equal to 21.3% of the value of BMD at T0, P<0.01) and 0.075 g/cm2(equal to 20.7% of the value of BMD at T0, P<0.01), which showed the disused osteoporotic models of left hind limbs were prepared successfully at T3. (2) The results of BMD (at T4-T10) of new zealand rabbits left hind femoral condyle showed:the values of BMD decreased from T4 to T6, and increased from T6 to T10; the range of the decreased value in MBG group was less than those in control group, while the range of increased value in MBG group was more than those in control group. The values of BMD in MBG group at T4-T10 were higher than those in control group(P<0.01). (3) The results of X-ray at T7 and T10 showed there was more bone quantity、denser bone quality of bone defects at 6 and 12 weeks after operation in MBG group than those in control group, and there was no obvious concaving deformation in condyles of femur at 6 and 12 weeks after operation in MBG group. (4) The results of general samples and bone microstructure examination at T5、T6、T7 and T10 showed the new bones quantity(general sample observation, mineral apposition rate of the new bone, trabecular number) and microstructure(bone volume fraction、trabecular number and trabecular spacing)of encapsulated bone defect and the surrounding area in MBG group were significanfly better than those in control group.Conclusion Implanting Mesoporous Bioactive Glass (MBG) in bone defects of osteoporotic area can induce new bone formation of the the surrounding areas, increase bone mineral density effectively, and improve the bone microstructure and the bone strength, which is helpful to the prevention and treatment of osteoporosis fracture. |
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