| Osteoporosis fracture is a disease that most threaten the life of aged people now. The characteristic of osteoporosis include bone strength degraded, microarchitecture broken and fragility increased which lend the osteoporosis fracture happened more easily. Once fracture happens, it is very difficult to be treated, and the therapeutic efficacies are not satisfactory which may badly affects patients'life, induced patients disabled,even died. Therefore, prevent and therapy in osteoporosis are highly important. Nowadays, for the osteoporosis, medical therapy is the primary measure. But the medical therapy have some of insufficiency, such as take long time, untoward effects evidently, therapeutic efficacies are slowly, so it is more difficult to increase the bone density and strength. Extracorporeal shock wave treatment have more effect in treatment of fracture and nonunion that testified by studies, especially in the process of bone formation. However, osteoporosis are displayed bone sorption enhancement and bone formation weaken. For this reason, in this study extracorporeal shock wave were applied to the osteoporosis animal bone tissue, according to the bone formation effect of extracorporeal shock wave, to investigate it would whether influenced the process of cancellous bone rebuild, increased bone density and improved bone quality or not.Part 1: Establishment of Rabbit Osteoporosis Model by Ovariectomy plus Dexamethasone Intramuscular InjectionObjective To investigate the feasibility of establish rabbit osteoporosis model by ovariectomy plus Dexamethasone intramuscular injection. Methods 24 five months old female New Zealand white rabbits were divided into three groups equally. Group A, shame operation plus Sodium Chloride intramuscular injection. Group B, ovariectomy plus Sodium Chloride intramuscular injection. Group C, ovariectomy plus Dexamethasone intramuscular injection. The bilateral ovaries of the last two groups were ectomized. Before operation and 2, 3 months after operation, the BMD were measured by double-energy X-ray absorption meter, respectively. 3 months after operation, micro-CT was used to detect the experimental rabbits. Result 3 months after operation, the BMD of lumbar spine and proximal femur in group C were 30.45% and 35.49% lower than those in group A espectively.The micro-CT reconstruction analysis showed that 3-months after operation, the difference of BMD, BMC and trabecula stereology parameter of distal femur have statistical value between group A and C. The trabecular of the distal femur in group B and group C all became raritas, breakage and disordered, of which, group C was much more obviously. Conclusion These results suggest that ovariectomy plus Dexamethasone intramuscular injection is a good method to establish New Zealand rabbit osteoporosis model. Three months are enough to establish the osteoporosis model using ovariectomy plus dexamethasone intramuscular infection, shorter than using only ovariectomy. Part 2: Effect of extracorporeal shock wave on femoral condyle trabecular bone in an osteoporosis rabbit modelObjective To investigate the treatment effects of extracorporeal shock wave(ESW) on femoral condyle in an osteoporosis rabbit in vivo. Methods Thirty New Zealand white rabbits used ovariectomy plus Dexamethasone intramuscular injection 3 months to establish osteoporosis animal model. All animals were randomized into 3 groups: group A (sham), group B (4 weeks of treatment) and C (8 weeks of treatment). In group B and C, high-energy shock wave (energy flux density: 0.47mJ/mm2, 2000 impuls) were applied to the right femoral condyles. All animals were sacrificed 4 (group B) or 8 (group C) weeks after ESW treatment, underwent micro-CT scan and histological examination. Results Micro-CT analysis showed that bone mineral density (BMD), bone mineral content (BMC) and micro-architectural parameters in group B and C were higher significantly than those in group A. The BMD in group C was 79.9% and 14.0% higher than that in group A and group B respectively. Although BMD, BMC and micro-architectural parameters in group C were higher than those in group B, no significant differences were detected between the two groups. Conclusion ESW can improve the reconstruction and remodeling of cancellous bone and increase the BMD and BMC in the osteoporosis rabbit model. It can be used as local treatment for osteoporosis.Part 3: Study on effect of different energy flux density extracorporeal shock wave on femoral condyle trabecular bone in osteoporosis rabbit modelObjective To investigate the difference of bone formation effects of different energy flux density extracorporeal shock wave on femoral condyle in osteoporosis rabbit in vivo. Methods Thirty New Zealand white rabbits used ovariectomy plus Dexamethasone intramuscular injection 3 months to establish osteoporosis animal model. All animals were randomized into 3 groups: group A (sham), group B were used 0.28 mJ/mm2 energy flux density extracorporeal shock wave and group C were used 0.47 mJ/mm2, shock wave pulses are 2000. The right femoral condyles of all the test animal were applied. All animals were sacrificed after ESW treatment 4 or 8 weeks, and underwent micro-CT scan.Results Micro-CT analysis showed that bone volume/tissue volume(BV/TV) and trabecular number(Tb.N) have significant differences on 4 weeks after ESW treatment between the group B and C. On 8 weeks after ESW treatment, the group C, bone mineral density (BMD), bone mineral content (BMC), bone volume/tissue volume(BV/TV), bone surface/tissue volume (BS/TV) and trabecular connectivity density were higher significantly than those in group B, the BMD and BMC in group C were 16.8% and 10.6% higher than those in group B respectively. Although the other micro-architectural parameters in group C were higher than those in group B on 8 weeks after ESW treatment, but no significant differences were detected between the two groups. Conclusion In a range, different energy flux density extracorporeal shock wave used on osteoporosis animal made different effect. It is showed that higher energy flux density extracorporeal shock improve the reconstruction , remodeling of cancellous bone and increase the BMD is better than lower. |
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