粗聚焦震波对大鼠骨质疏松性骨折愈合的影响及生物力学评估

Effect of unfocused shock wave on the healing of osteoporotic fractures in rats and the biomechanical evaluation

目的观察粗聚焦震波对大鼠骨质疏松性骨折愈合过程中的骨密度、骨微结构及愈合后生物力学特性的影响。方法 66只体重为200～250 g的3月龄雌性SD大鼠卵巢去势制造骨质疏松模型,造模成功后左腿胫骨制造开放性骨折并予克氏针内固定。术后分为对照组和治疗组,治疗组用震波能量密度0.26 mJ/mm2,频率60次/分,冲击量为2000次治疗一次。结果治疗后4周和8周行组织学观察显示治疗组与对照组比较骨性骨痂所占比例较大,8周时骨小梁改建基本完成;而Micro CT检验数据结果显示治疗组骨密度(BMD);骨小梁体积(BV)、组织体积(TV)、骨体积分数(BV/TV)、平均骨小梁厚度(Tb.Th)、平均骨小梁数目(Tb.N)均明显高于对照组(P<0.05),其中治疗8周后的骨密度改变存在显著差异(-3.6%vs 4.9%,P<0.05)。且治疗组最大压缩荷载在治疗后4周(48.1±5.6(治疗组)vs21.8±4.8(对照组))、8周时亦明显高于对照组(57.5±6.1(治疗组)vs28.6±5.0(对照组))。结论粗聚焦震波能够抑制骨折后的骨丢失,增加骨密度,促进骨折愈伤组织的生长,改善骨小梁三维结构及骨组织的力学性能,可用来促进骨质疏松性骨折的愈合并改善骨质量,预防再骨折。

Objective To observe the effect of unfocused shock wave on bone mineral density （BMD） and bone micro - structure during the healing process of osteoporotic fractures, and the characteristics of biomechanics after healing in rats. Methods A total of 66 3 - month, 200 - 250g, female SD rats were selected. After ovariectomization and successful osteoporotic model building, left tibial open fractures were made and all the fractures were internal fixed with kirschner pins. After the operation, all the 66 rats were divided into control group and treatment group. Rats in treatment group were treated with unfocused shock wave once, with the energy density of 0.26mJ/mm^2 , at the frequency of 60 each minute, and 2000 impact quantities. X ray, micro CT, and biomechanical test were performed to investigate the results. Results Histological observation at 4 and 8 weeks after the treatment showed more osseous callus formation in treatment group than in control group. The bone remodeling almost finished at 8 weeks after the treatment. Micro-CT showed that BMD, bone trabecular volume （BV） , tissue volume （TV） , BV/TV, Tb. Th, and Tb. N were significantly higher in the treatment group than those in control group （P 〈 0.05 ）. After 8-week treatment, BMD changed significantly （ - 3.6% vs 4.9% , P 〈 0. 05 ）. After 4-week treatment, the ultimate load in control group and treatment group was 21.8 ± 4.8 and 48.1 ± 5.6, respectively. After 8-week treatment, it was 28.6 ± 5.0 and 57.5 ± 6.1 , respectively （ P 〈 0.05 ）. Conclusion Unfocused shock wave can inhibit bone mass loss after fractures, increase BMD, promote the growth of callus, and improve the 3D structure of bone trabecular and mechanic characteristics of bone tissue. So it can be used to promote the healing of osteoporotic fractures,to improve quality,and to prevent recurrence of fractures.