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目的 :探讨椎体内注射辛伐他汀/泊洛沙姆407温敏型智能水凝胶对骨质疏松小型猪腰椎骨质和椎弓根螺钉内固定稳定性的影响。方法:9只健康成年雌性广西巴马小型猪,行双侧卵巢切除术,术后低钙饮食18个月,双侧卵巢切除后18个月小型猪腰椎骨密度(bone mineral density,BMD)较切除前降低了25.23%,即骨质疏松模型建立成功。每只骨质疏松小型猪采取自身对照,将3个腰椎(L4~L6)进行随机分组,在椎体左侧钉道内单次注射载辛伐他汀0、0.5、1.0mg的水凝胶,并分别在两侧置入钛合金椎弓根螺钉。3个月后处死,取出每只小型猪的椎体(L4~L6),剔除椎体周围软组织,在各椎间盘处离断,游离成单个椎体,用双能X线骨密度仪检测BMD,行Micro-CT扫描并定量分析骨小梁微结构及骨整合率,内固定螺钉轴向拔出实验,不脱钙骨组织学观察。结果:辛伐他汀0.5mg、1mg组椎体与给药前相比,BMD分别增加了32.12%和28.16%,辛伐他汀0.5mg、1mg组椎体与辛伐他汀0mg组相比,BMD分别增加了31.25%和31.09%(P均<0.01);辛伐他汀0.5mg、1mg组与辛伐他汀0mg组相比,相对骨体积(BV/TV,%)分别增加了47.49%和43.42%,骨小梁数量(Tb.N)分别增加了49.23%和39.01%,骨小梁厚度(Tb.Th)分别增加了66.09%和54.28%,骨小梁间隙(Tb.Sp)分别降低了55.85%和52.80%,骨整合率分别增加了46.54%和42.63%(P均<0.01);辛伐他汀0.5mg与1mg组的最大轴向拔出力(Fmax)与辛伐他汀0mg组相比,分别增加了45.75%和51.53%(P<0.01);组织学观察发现辛伐他汀0.5mg、1mg组螺钉周围骨小梁明显增多,钉骨接触面积明显增大。结论:骨质疏松小型猪腰椎椎体内单次注射低剂量辛伐他汀可促进骨形成,增加骨密度,改善骨骼微结构,增加骨整合率,显著提高椎弓根螺钉在骨质疏松椎体中的稳定性。
OBJECTIVE: To investigate the effect of injecting simvastatin / poloxamer 407 thermo-sensitive hydrogel on stability of lumbar vertebrae and pedicle screw fixation in osteoporosis mini-pigs. Methods: Nine healthy adult female Bama miniature pigs underwent bilateral oophorectomy. After low-calcium diet for 18 months, the bone mineral density (BMD) of miniature pigs at 18 months after bilateral ovariectomy Before excision reduced by 25.23%, that is, osteoporosis model was established successfully. Each osteoporosis minipig adopts self-control, and randomly divided 3 lumbar vertebrae (L4 ~ L6) into a single injection of simvastatin 0,0.5,1.0mg hydrogel in the left lateral vertebral canal Titanium screws were placed on both sides of the pedicle screw. Three months later, the vertebral bodies (L4 ~ L6) of each miniature pig were removed, the soft tissues around the vertebral bodies were removed, and the vertebral bodies were separated at each intervertebral disc and were dissociated into single vertebral bodies. BMD was measured by dual energy X-ray absorptiometry Micro-CT scanning and quantitative analysis of trabecular bone microstructure and rate of bone consolidation, axial fixation screw removal experiment, not decalcified bone histological observation. Results: The BMD of simvastatin 0.5mg and 1mg group were increased by 32.12% and 28.16% compared with those before administration, respectively. Compared with simvastatin 0.5mg and 1mg group, BMD (BV / TV,%) increased by 47.49% and 43.42% respectively compared with simvastatin 0.5mg, 1mg group and simvastatin 0mg group (P <0.01) The number of trabecular (Tb.N) increased by 49.23% and 39.01%, the trabecular thickness increased by 66.09% and 54.28% respectively, the Tb.Sp decreased by 55.85% And 52.80% respectively. The bone consolidation rate increased by 46.54% and 42.63% respectively (P <0.01). Compared with simvastatin 0 mg group, the maximum axial pullout force (Fmax) of simvastatin 0.5 mg and 1 mg group Increased by 45.75% and 51.53%, respectively (P <0.01). Histological observation showed that the trabecular bone around the screw of simvastatin 0.5mg and 1mg group increased obviously, and the contact area of nail increased obviously. Conclusion: Single injection of simvastatin in the lumbar vertebral body of osteoporosis can promote bone formation, increase bone density, improve the microstructure of bone, increase the rate of bone consolidation, and significantly improve the stability of pedicle screws in osteoporotic vertebral body In the stability.