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Objective To investigate the effects of locally and systemically administered alendronate on wear-debris induced osteolysis in vivo. Methods Endotnxin-free titanium particles were injected into rabbit femurs prior to insertion of a non-weight-bearing polymethylmethacrylate plug into the distal femur canal. Then the particles were repeatedly injected into the knee 2, 4 and 6 weeks after the implantation. Alendronate was incorporated into bone cement for local delivery at three different concentrations [0.1, 0.5, and 1.0 weight%(wt%)]. For systemic delivery, alendronate was subcutaneously injected ( 1.0 mg· kg-1·week-1).Results Eight weeks after operation, there was significant evidence of osteolysis surrounding the plug in the control group, while markedly-blocked osteolysis was noted in the local delivery group (0.5 wt% and 1.0 wt%), and the systemic delivery group. It was found that alendronate had improved peri-prosthetic bone mineral density in a dose-effect model. Notably, no significant difference was found between local delivery of 0.5 wt% alendronate and systemic delivery in bone mineral density and implant fixation. Conclusion Alendronate-loaded bone cement (0.5 wt% ) may be as effective as the systemic delivery in inhibiting titanium particle-induced osteolysis.
RESUMO
objective: To observe the variations of stress magnitude in the cervical vertebra exerted by vertical traction force from various angles and different points. Methods: The cervical vertebra model was produced by using elastic material of light (polycarbonate) and silica rubber(1:1). By calculating the arithmetical progression of interference fringe. The author judged the stress magnitude in the posterior edge of the C4-7 vertebral bodies when different kinds of pulling force acted on. Result: The interference pattern was seen clearly on the screen while the force acted on the model. When the pulling force acted on C1 or C2, the force was acting at an angle of 150the maximum of the stress presented in C4-5 and when the force acted at an angle of 25° the maximum stress presented in C5-6 and C6-7. Conclusion: The stress distributed upon the posterior edge of the vertebral joints is closely related to the points that the force aced on and the direction of the force． Appropriate points and direction of the pull should be selected according to the change of the lesion joints when manual manipulation is used for the treatment of cervical vertebral disease.