高正加速度重复暴露环境对SD大鼠种植体骨结合的影响

The effects of repeated high acceleration on implant osseointegration in SD rats

目的:以小动物离心机模拟飞行员高正加速度(+Gz)暴露环境,观察其对SD大鼠种植体骨结合的影响。方法:18只SD大鼠随机分为+Gz重复暴露组和对照组,每组9只,每只动物左右侧股骨远心端分别植入一枚纯钛种植体。术后24 h内实验组进入+Gz暴露环境,4~9 G 1 G/s逐渐增加,每周3次,对照组不作特殊处理。分别于2、4、8周随机处死两组各3只动物取材,进行micro CT扫描、双荧光标记和组织学分析,观察种植体周围骨结合情况。结果:2周时,+Gz重复暴露组骨体积分数(BV/TV)、骨小梁数量(Tb.N)、新骨沉积速率(MAR)、种植体-骨接触率(BIC)、种植体周围新骨生成量(BA)均显著低于对照组(P<0.05),骨小梁间隙(Tb.Sp)显著高于对照组(P<0.01);4周时,+Gz重复暴露组MAR、BA显著低于对照组(P<0.05);8周时两组各指标均无统计学差异。结论:种植体植入后即刻进入+Gz重复暴露环境使SD大鼠骨结合初期形成速度减缓;但随着+Gz加载时间的延长,这种不利影响逐渐消退,最终达到与对照组相似的骨结合情况。

Objective:To investigate the effects of repeated high acceleration(+Gz)on implant osseointegration in SD rats.Methods:18 SD rats were divided into+Gz and control groups randomly(n=9),and 1 implant was placed in each femur of the rat's lower limb.24 hours postoperatively,the experimental rats were exposed to+Gz of 4 to 9 G with 1 G/s environment 3 times a week,while the control rats were fed normally.3 rats from each of the 2 groups were sacrificed at 2,4 and 8 weeks after implantation.Micro-CT,sequential fluorescence double labeling,and histological examination were perfomed for the analysis of implant osseointegration.Results:The bone volume fraction(BV/TV),trabecular number(Tb.N),mineral apposition rate(MAR),implant-bone contact rate(BIC)and bone area in implant thread(BA)of the+Gz group were significantly lower than those of the control group at 2 weeks(P<0.05),and so as to MAR,BA at 4 weeks(P<0.05),while there was no significant difference of the parameters at 8 weeks after implantation.Conclusion:In SD rats early exposure to+Gz environment postoperatively may have a negative effect on initial osseointegration by slowing bone formation.However,it will not lead to poorer bone mass when sustained over a long period.