微波促进钛合金内固定骨折术后骨愈合的实验研究

Treatment effect of microwave on fracture with titanium alloy internal fixation

目的探讨钛合金内固定骨折术后微波治疗的安全性及其对骨愈合的影响。方法选31只新西兰大白兔,建立兔股骨干骨折钛合金植入模型。动物建模术后3 d,取15只模型动物,根据微波照射功率不同分为:20W组、40 W组及60 W组,每组5只。采用实时温度测量方法测定不同剂量各组微波照射时钛合金,钛合金周围肌肉组织及对照侧肌肉组织温度变化,确定动物模型的治疗剂量。将另16只模型动物随机分成实验组(连续波型照射),对照组(模拟治疗),每组8只。对兔股骨骨折钛合金植入模型给予30 d治疗剂量的微波照射。采用X线平片射线相对密度定期评价骨折愈合。治疗结束处死动物,观察HE染色及电镜下组织形态,检测组织中caspase-3,caspase-9 mRNA及蛋白表达,评价钛合金周围组织热损伤。结果动物模型的治疗剂量为25 W 10 min。实验组与对照组相比,植入物毗邻肌肉、神经组织及骨组织无明显的形态学变化,两组骨骼肌caspase-3,caspase-9mRNA及蛋白表达差异不显著(均P>0.05)。X线平片结果表明照射第10天两组骨折愈合差异明显(P=0.03),而第30天两组差异不显著(P=0.12)。骨组织病理学评分结果表明微波治疗可促进骨折愈合。结论小剂量微波治疗不会对钛合金植入物周围组织造成不可逆热损伤且可有效促进钛合金内固定术后骨折愈合。

Objective To study effect of microwave treatment on fracture healing with titanium alloy internal fixation.Methods Titanium alloy internal fixation systems were implanted in rabbits withthigh bone fracture. Temperature changes of muscle tissues around implants were measured during the irradiation for seeking a reasonable dose. Then rabbits in treatment group began to receive microwave treatment 3 days after operation. Normalized radiographic density of the fracture gap was measured. All of the animals were killed after 10 and 30 days microwave treatment,and then histological examinations were performed on the harvested muscles,nerves and bone tissues. The expression of caspase- 3,- 9 was analyzed by real time- PCR and western blot. Results No abnormal morphological changes were shown in nerve and bone around the implants of microwave treatment group. But some reversible damages were observed occasionally in muscles,including swelling myocytes with light microscopy and mitochondrial swelling with transmission electron microscopy. The expression of caspase- 3,caspase- 9 didn＇t rise significantly（ both P〈0. 05）. Radiographic assessments showed that fracture healingwas accelerated especially on the 10 th day of the microwave treatment（ P = 0. 03）,while no significant difference on the30 th day（ P = 0. 12）. Conclusion Low power microwave treatment would be helpful in the healing of fractures with titanium alloy internal fixation.