不同骨密度防腐标本椎体成形术后生物力学及渗漏率的研究

The biomechanical and cement leakage study of the different bone mineral density embalmed verte- bral body after vertebroplasty

目的探讨骨密度对防腐标本椎体成形术后生物力学及骨水泥渗漏率的影响并分析其原因。 方法取防腐标本9具，年龄（65±3）岁，每个标本取T11～L3椎体。利用双能X线数字闪烁式二维全身骨密度仪（DEXA，OSTE0COREⅢ型）测量每个椎体的骨密度（BMD），根据BMD值筛选出30个椎体标本，按照单因素随机分为骨量较好组（A组）、骨量一般组（B组）、骨量较差组（C组）。压缩制备成椎体骨折模型后行椎体成形术，术后行生物力学实验，CT扫描统计渗漏例数，应用SPSS 21.0统计软件进行统计分析。 结果3组椎体标本注入骨水泥后最大垂直载荷和刚度分别为A组：（5 178.43±903.17） N、（427.01±171.85） N/mm；B组：（4 630.49±504.542） N、（385.67±101.49） N/mm；C组：（3 476.67±757.29） N、（302.76±70.95） N/mm。术后最大垂直载荷组间比较差异有统计学意义（F＝13.772，P＝0.000），其中C组和A、B两组比较差异有统计学意义。术后刚度组间比较差异无统计学意义（χ2＝4.376，P＝0.112）。3组骨水泥渗漏率分别为60%、50%、30%（A组6例、B组5例、C组3例），差异无统计学意义（P＝0.534）。 结论防腐标本椎体成形术后，骨密度与椎体最大垂直载荷及骨水泥渗漏率均呈正相关，对刚度恢复无明显影响。

Objective To explore the differences of biomechanics and cement leakage among dif- ferent bone mineral density （BMD） embalmed vertebral body after vertebroplasty. Methods Forty - five vertebral bodies were harvested from 9 embalmed cadavers. BMD of the vertebral body was measured using dual emission X -ray absorptiometry （DEXA）. According to their BMD, vertebral bodies were divided in- to 3 groups ： preferable bone mass group （ A, n = 10） ; general bone mass group （ B, n = 10） , poor bone mass group （C ,n = 10）. All specimens were selected to make into compression fracture model by the bio- mechanical machine for further test. After fracture vertebroplasty was performed, all vertebral bodies underwent unilateral vertabroplasty, with 2. 5 ml bone cement injection for each vertebral body. The biomechani- cal testing was carried out before the fracture and after cement injection. The cement leakage rate and dis- tribution of cement were assessed with the reference of postoperative CT scan （ group A, 6 cases ; group B, 5 cases; group C, 3 cases）. Results In groups A, B and C the intensity and stiffness after cement injection were （5 178.43 ±903.17） N, （4 630.49 ±504.542） N, （3 476.67 ±757.29） N; （427.01 ± 171.85） N/mm, （302. 76 ± 70. 95） N/ram, （385.67 ± 101.49 ） N/mm, respectively. After vertabroplasty the intensity was statistically significant among 3 groups （ F = 13. 772 ,P =0. 000）, and the stiffness showed no significant difference （χ2 =4. 376,P =0. 112）. The leakage rate was higher in group A than in group B and C but have no statistically significant （ P =0. 534）. Conclusion The BMD, maximum load strength and bone cement leakage rate were positively related after vertebroplasty. The recovery of stiffness was not influenced by BMD.