利塞膦酸钠干预骨质疏松大鼠股骨骨折愈合的实验研究

Experimental study of risedronate on the healing of femur fracture in osteoporosis rats

目的观察双膦酸盐类(bisphosphonates,BPs)药物利塞膦酸钠对骨质疏松大鼠股骨骨折愈合各个阶段影像学、组织病理学及生物力学等方面的影响及其可能机制。方法将健康6月龄Sprague-Dawley(SD)雌性大鼠90只,随机分为空白对照组、干预组和安慰剂组,每组30只。干预组和安慰剂组大鼠行卵巢切除术建立骨质疏松模型,空白对照组行假手术。继续喂养4周后,3组大鼠均行股骨干骨折手术。术后干预组给予利塞膦酸钠灌胃治疗,安慰剂组和空白对照组仅予0.9%氯化钠溶液灌胃。分别在骨质疏松骨折手术前、骨折手术后第3周和第6周时,观察和比较3组大鼠骨骼影像学、骨组织显微形态学、股骨骨密度(BMD)、骨矿物质含量(BMC)、生物力学指标。结果X线摄片发现,骨折手术后第3周时,干预组骨折处骨连续性较空白对照组和安慰剂组好;但在骨折手术后第6周时,干预组大鼠骨折处骨连续性较空白对照组和安慰剂组差。骨折愈合组织的组织病理学检查发现,与空白对照组、安慰剂组相比,在骨折手术后第3周时,干预组大鼠骨折处软骨细胞增殖较多,骨小梁较密集,骨小梁相互之间连接性较好,骨皮质厚度更大,骨折愈合情况更好;但在骨折手术后第6周时,干预组大鼠骨折处增殖的软骨细胞较少,骨小梁稀疏,骨小梁相互之间连接性差,骨皮质厚度变化不明显,出现骨折愈合延迟现象。3组大鼠BMD值均随时间延长而增高(P值均<0.01);在骨折手术后第3周和第6周时,干预组BMD值均显著高于安慰剂组同时间点(P值均<0.01)。空白对照组大鼠BMC值随时间延长增高,干预组和安慰剂组均随时间延长而降低(P值均<0.01);在骨折手术后第3周和第6周时,干预组BMC值均显著高于安慰剂组同时间点(P值均<0.01)。干预组和安慰剂组大鼠骨折手术后第6周时股骨的最大载荷、最大载荷恢复率分别显著低于同组骨折手术后第3周时(P值均<0.01);在骨折手术后第3周和第6周时,干预组大鼠股骨的最大载荷、最大载荷恢复率均显著高于安慰剂组同时间点(P值均<0.01)。结论利塞膦酸钠能提高骨质疏松性大鼠股骨骨折愈合过程中新生骨痂结构强度和生物力学指标,但长期使用可能影响骨重塑能力。

Objective To explore the effect of risedronate sodium,a kind of bisphosphonates(BPs),on femoral fracture healing in osteoporotic rats from the aspects of imaging,histopathology and biomechanics and its possible mechanism.Methods Ninety healthy 6-month-old Sprague-Dawley(SD)female rats were randomly divided into 3 groups:blank control group,intervention group and placebo group(n=30).The model of osteoporosis was established in intervention group and placebo group by oophorectomy.Sham operation was performed in blank control group.After 4 weeks of continuous feeding,all rats in the three groups underwent femoral shaft fracture surgery.Then risedronate sodium was administered in the intervention group,and normal saline was given in the placebo group and blank control group.The imaging,bone tissue micromorphology,femoral bone mineral density(BMD),bone mineral content(BMC)and biomechanical indicators were observed before osteoporotic rat fracture surgery,and at the 3rd and 6th weeks after fracture surgery.Results X-ray photography found that,compared with the blank control group and placebo group,there was more continuous bone at the fracture in the intervention group at the 3rd week after fracture surgery and less continuous bone at the 6th week after fracture surgery.Histopathological examination revealed that at the 3rd week after fracture surgery,compared with the blank control group and placebo group,the rats in the intervention group had more proliferated chondrocytes at the fracture,dense trabecular bones,better connection between trabecular bones,thicker bone cortex and better fracture healing;but at the 6th week after fracture surgery,there were few cartilage cells proliferating at the fracture in the intervention group,the trabecular bones were sparse,the connectivity was poor between trabecular bones,the thickness of the bone cortex did not change significantly,and the fracture healing was delayed.The BMD of rats in the three groups increased with time(all P<0.01).At 3th and 6th weeks after surgery.The BMC of rats in the blank control group also increased with time,but the BMC in the intervention group and placebo group were decreased(all P<0.01).Both BMD and BMC of the intervention group were significantly higher than those of the placebo group at 3th and 6th weeks after fracture surgery(all P<0.01).In the intervention group and the placebo group,the maximum load and the recovery rate of the maximum load of the callus at 6 weeks after fracture surgery were lower than those at 3 weeks(all P<0.01).The maximum load and the maximum load recovery rate in the intervention group were higher than those in the placebo group at 3 and 6 weeks after the fracture surgery(all P<0.01).Conclusion Risedronate improves the structural strength and biomechanical indicators of the new callus during the healing of femoral fractures in osteoporotic rats,but long-term use may affect bone remodeling.