硫酸钙骨水泥在骨折椎体成形术中的力学性能

Biomechanical Properties of Calcium Sulfate Vertebroplasty Combined with Posterior Trans-Pedicle Screw Fixation in Treatment of Thoracolumbar Compression Fracture

目的评价硫酸钙骨水泥在胸腰椎压缩性骨折椎体成形术中的生物力学性能。方法采集15具新鲜成年小牛胸腰椎标本,制成T11~L1脊柱功能单位,随机分为A、B、C三组各5具,正常完整标本组（A组）,后路复位椎弓根钉固定组（B组）,后路复位椎弓根钉固定结合硫酸钙椎体成形组（C组）。B、C组标本制成T12椎体屈曲压缩性骨折模型,分别采用后路复位椎弓根钉固定及后路复位椎弓根钉固定结合硫酸钙椎体成形。三组标本在WE-10型万能材料试验机上加载不同级别载荷,检测脊柱功能单位的载荷-应变关系、载荷-位移关系、强度、刚度等生物力学性能,试验数据进行统计学处理,并进行组间比较。结果胸腰椎功能单位抗压强度,A、B、C三组分别为（2488±224）N、（3 368±310）N、（4 283±404）N,B、C之间相差21%,差异有统计学意义（t=1.422,P〈0.05）;A、C之间相差42%,差异有统计学意义（t=1.814,P〈0.05）。胸腰椎功能单位刚度,A、B、C三组分别为（400±32）N/mm、（455±42）N/mm、（638±61）N/mm,B、C之间相差29%,差异有统计学意义（t=1.792,P〈0.05）;A、C之间相差37%,差异有统计学意义（t=2.628,P〈0.05）。结论经后路椎弓根螺钉固定结合硫酸钙椎体成形术治疗胸腰椎压缩性骨折的生物力学性能优越,术后不但强度大、刚度高,而且承载能力大,椎体高度恢复满意;术后的胸腰椎稳定,极大地分担内固定物的应力负荷,进而降低螺钉的松动、折断发生率及术后椎体高度的丢失。

Objective To assess the biomechanical properties of calcium sulfate vertebroplasty combined with posterior trans-pedicle screw fixation in treatment of thoracolumbar compression fractures.Methods Fifteen fresh bovine T11-L1 function spine unites（FSU） were collected and divided into three groups randomly：normal control group（A group,n=5）,trans-pedicle screw fixation group（B group,n=5） and vertebroplasty group（C group）.T12 flexion-compression fracture model were made in all specimens of B、C group,only reduction with posterior trans-pedicle screw fixation was performed in B group and calcium sulfate vertebroplasty combined with posterior trans-pedicle screw fixation was performed in C group.Fifteen specimens of 3 groups were placed on the WE-10A universal testing machine and accepted different loading.Biomechanical characters of load-straining,load-displacing,rigidity,strength of the SFU were performed.The experimental outcome were collected and compared by statistic analysis.Results Compression strength of FSU in A,B,C group was（2 488±224） N、（3 368±310） N、（4 283±404） N respectively,C group were 21% and 42% higher than that of B、A group.The thoracolumbar stiffness of A,B,C group was（400±32） N/mm、（455±42） N/mm、（638±61） N/mm respectively,C group were 29% and 37% higher than that of B、A group.The data above were significant differences statistically（P〈0.05）.Conclusion The biomechanical properties of calcium sulfate vertebroplasty combined with posterior trans-pedicle screw fixation in treatment of thoracolumbar compression fractures not only have strong strength and stiffness,but also have a stable function spine unit,which could decrease the stress loading of the internal fixation,decrease the incidences of screw breakage and avoid the lose of the vertebral.height.