后凸成形骨水泥强化技术在骶骨钉翻修中的生物力学作用  

Biomechanical Effect of Kyphoplasty-Assisted PMMA Augmentation on Sacral Screw Fixation Strength

作　　者：庄新明[1] 于滨生[1] 郑召民[1] 李泽民[1] 王泰平[1] 

机构地区：[1]中山大学附属第一医院脊柱外科∥骨科研究所,广东广州510700

出　　处：《中山大学学报（医学科学版）》2010年第4期503-507,共5页Journal of Sun Yat-Sen University:Medical Sciences

基　　金：广东省科技计划项目(2008B050100012);广东省医学科研项目(A2008161)

摘　　要：【目的】评价后凸成形骨水泥(PMMA)强化技术对骨质疏松情况下骶骨钉固定强度的生物力学影响,为骶骨钉翻修选择坚强的补救技术提供依据。【方法】11具新鲜骶骨标本用于实验,双能X线吸收法(DEXA)评价骨密度。在同一骶骨上,依次建立非PMMA强化和PMMA强化骶骨钉的固定模型如下,A组:单皮质椎弓根钉;B组:双皮质椎弓根钉;C组:传统PMMA强化单皮质椎弓根钉;D组:后凸成形PMMA强化椎弓根钉;E组:后凸成形PMMA强化侧翼钉。在MTS试验机上对五种骶骨钉依次进行轴向拔出测试,记录最大承受拔出力并比较。【结果】11具标本的平均骨密度为(0.71±0.08)g/cm2。A组的螺钉拔出力(508N)显著低于其它4种固定组(P<0.05)。B组的螺钉拔出力(685N)与E组(702N)无显著差异(P>0.05),但是,两者的拔出力均显著低于C和D组(P<0.05)。重要的是,D组(986N)的拔出力显著高于C组(846N)。【结论】在骨质疏松患者的骶骨固定中,双皮质骶骨椎弓根钉较单皮质具有显著的力学优势。骶骨椎弓根钉一旦发生松动,传统的和后凸成形PMMA强化技术均可成为补救手段,并且后凸成形PMMA强化骶骨椎弓根钉可获得最坚强的锚定。【Objective】 To evaluate the biomechanical effect of kyphoplasty-assisted polymethylmethacrylate （PMMA） augmented technique on the sacral screw fixation strength in osteoporotic condition,and provide evidences for choosing rigid salvage techniques for sacral screw revision. 【Method】 Eleven fresh osteoporotic cadaveric sacra were used in this study and bone mineral density （BMD） of each specimen was measured by dual-energy radiograph absorptiometry （DEXA）. Sacral screws with and without PMMA augmentation were sequentially established on the same sacrum as follows,Group A：unicortical pedicle screw; Group B：bicortical pedicle screw; Group C：pedicle screw with traditional PMMA augmented technique; Group D：pedicle screw with kyphoplasty-assisted PMMA augmentation; Group E：ala screw with kyphoplasty-assisted PMMA augmentation. Axial pull-out resistance of the five screws was sequentially tested on a MTS material testing machine,and the maximum bear pull-out strengths were measured for comparison. 【Results】 The average BMD of 11 specimens was 0.71 ± 0.08 g / cm2. Group A （508 N） exhibited significantly less pull-out strength compared with all the other groups （P〈 0.05）. No statistical difference on pull-out strength was detected between Group B （685 N） and E （702 N） （P 〉0.05）; however,the two techniques exhibited markedly lower pull-out strength than Group C and D （P〈 0.05）. Importantly,the pull-out strength in Group D （986 N） was obviously higher than that in Group C （846 N）. 【Conclusions】 For sacral screw fixation of osteoporotic patient,bicortical sacral pedicle screw could acquire significant mechanical advantage over unicortical. Once the loosening of pedicle screw occurs,the traditional and kyphoplasty-assisted PMMA augmentations may serve as a suitable salvage technique. Moreover,the sacral pedicle screw with kyphoplasty-assisted PMMA augmented technique may obtain the most rigid anchoring strength.

关 键 词：腰骶融合 骨质疏松 骶骨钉 骨水泥强化 生物力学 

分 类 号：R68[医药卫生—骨科学]