【作者】 刘瑶瑶；

【导师】 许建中；

【作者基本信息】 第三军医大学 ， 外科学， 2012， 博士

【摘要】 随着世界人口老龄化的到来，越来越多的骨质疏松症(Osteoporosis, OP)患者因相关脊柱疾病需行内固定治疗。椎弓根螺钉内固定技术因其短节段、三柱固定等特点成为最为常用的脊柱后路内固定技术。然而，在骨质疏松椎体中由于骨矿物质密度（Bonemineral density, BMD）降低、骨小梁数目（Trabecular number, Tb. N）减少、骨皮质变薄，使椎弓根螺钉把持力下降，极易发生松动、拔出，致脊柱复位、固定失败。因此，如何提高椎弓根螺钉在骨质疏松椎体中的稳定性已成为当前脊柱外科所面临的一个挑战。本课题组在前期研究中设计出可注射骨水泥椎弓根螺钉（Bone cement injectablecanulated pedicle screw, CICPS），初步实验证实CICPS可有效提高椎弓根螺钉的稳定性，降低聚甲基丙烯酸甲酯骨水泥（Polymethylmethacrylate, PMMA）椎管泄漏几率，并避免螺钉直径和长度的增加所带来的风险。然而，将CICPS设计为中空后机械性能有何变化？与普通椎弓根螺钉（Conventional pedicle screw, CPS）及同类产品——韩国DTPSTM椎弓根螺钉(DTPSTM, Dream Spine Total Solutions, Dream STS, Seoul, Korea)相比在力学稳定性方面谁更具有优势？CICPS的临床效果如何？目前国内外还没有相关的研究报道。本课题就是围绕这几方面问题展开的。目的：1)检测CICPS与CPS的最大剪切力，了解螺钉设计为中空后机械性能的变化。2)通过体外标本实验比较CICPS、CPS钉及DTPSTM椎弓根螺钉的生物力学稳定性，分析骨水泥使用量与螺钉最大轴向拔出力(The maximum pullout strength, Fmax)之间的关系，为优化骨水泥使用量提供参考。3)通过初步临床实验探讨CICPS的安全性及有效性，为CICPS的广泛临床应用提供理论依据。方法：1)体外实验部分：对CICPS及CPS行剪切力实验，比较螺钉设计为中空后机械强度的变化。CICPS和DTPSTM分为四组，分别注入1ml，2ml，3ml，5ml骨水泥。将CPS和各组骨水泥螺钉按外科手术方法置入OP生物力学实验模块（Biomechanicaltest block, BTB）中，待骨水泥固化后行X光、CT检查，并置于材料试验机（Materialtesting system, MTS）上行轴向拔出力实验，分析骨水泥使用量与Fmax之间的关系，比较三种螺钉生物力学稳定性特点。2)临床实验部分：2010年至2012年我科共收治OP伴脊柱疾病需行内固定治疗患者24例，均予以CICPS强化固定。记录手术相关并发症，包括骨水泥泄漏、栓塞及感染等。出院后定期随访，随访内容包括视觉模拟疼痛评分（Visual analog scale,VAS)，Oswestry功能障碍指数（Oswestry disability index, ODI)，X光、CT（超过6月）。分析比较术前、术后、末次随访患者临床表现、下肢功能改善情况，内固定松动、拔出情况及骨融合情况。并在影像学检查中对各病种所特有的评价指标作专门的统计。如测量腰椎滑脱病例的滑脱百分比Taillard指数，椎间隙高度及滑脱角，以评价椎体复位和维持情况。结果：1)体外实验部分①剪切力实验：由于螺钉中空设计，CICPS最大剪切力显著低于CPS，但足以满足生理条件下脊柱内固定强度需求。②轴向拔出力实验：骨水泥强化组Fmax显著高于CPS。Fmax随骨水泥使用量的增加而增大，呈高度正相关性。骨水泥使用量为1~3ml时，CICPS Fmax显著高于DTPSTM。CICPS各个侧孔均有骨水泥流出，仅分布于螺钉前部，弥散均匀广泛；BTB中未见向后泄漏，椎体标本中未见椎管内泄露。骨水泥弥散于骨小梁中形成“螺钉-骨水泥-骨小梁”复合体，使螺钉锚定于椎体中。而DTPSTM中骨水泥主要从椎弓根螺钉的近端侧孔流出，远端侧孔较少。骨水泥使用量为5ml时，DTPSTMFmax高于CICPS。两者骨水泥弥散形态类似。2)临床实验部分纳入24例患者均获随访，平均随访时间为6.96±4.68月（3~23月）。与术前相比，末次随访VAS评分、ODI评分显著低于术前，疼痛感及下肢功能明显好转。未发现骨水泥椎管内泄漏；椎体前方静脉丛泄漏4例，但无神经症状。所有患者均未出现栓塞、感染等并发症。术后末次随访影像学检查无椎弓根螺钉松动、拔出，内固定位置良好。术后超过6月的患者骨融合率为100%。其中10例腰椎滑脱症患者，随访Taillard指数、滑脱角与术前相比显著性下降，而椎间隙高度则显著性提高。结论：1) CICPS增强椎弓根螺钉稳定性的效果显著优于CPS和同类产品。骨水泥使用量为1ml时，即可达到满意的内固定强化效果。在减少骨水泥使用量的同时，降低了骨水泥泄漏风险。2)中空设计使CICPS剪切力低于CPS，但足以满足临床需求。3)在骨质疏松椎体中，CICPS骨水泥弥散仅位于螺钉前端，分布均匀，有效降低使用骨水泥可能带来的热损伤、渗漏和神经压迫等并发症。4) CICPS临床应用疗效显著，患者术后恢复良好，无螺钉松动、拔出发生。因此，CICPS可作为OP伴脊柱疾病患者内固定治疗的一种安全、有效且操作简便的新选择。更多还原

【Abstract】 Background: As the world aging population grows, more and more osteoporosispatients need internal fixation for spinal diseases. Pedicle screw fixation technique is mostcommon for posterior spinal fixation as its features of short segment and three columnsfixation. However, decreasing bone mineral density (BMD) and trabecular numbers (Tb. N)and thinning cortical bones lower down the stability of pedicle screw to cause failure of theoperation. How to improve the stability of pedicle screw in osteoporotic vertebral hasbecome a challenge for spinal surgery.According to the previous research, we have designed the bone cement injectablecanulated pedicle screw (CICPS). It has been proved that CICPS can significantly increasethe stability of the pedicle screw, and reduce the risks caused by polymethylmethacrylate(PMMA) leakage or increasing length and diameter of screw. However, does the hollowdesign of CICPS cause any change in mechanical properties? Compared with conventionalpedicle screws (CPS) and DTPSTM(Dream Spine Total Solutions, Dream STS, Seoul,Korea) who has the most advantages in stability of biomechanics? How about the clinicalefficacy of CICPS? None of these is mentioned in the related materials in China or abroad.Objective:1) To observe the distribution of bone cement by X-ray and CT and compare themechanical properties between CICPS and CPS by analyzing the maximum shear stress.2) To compare the biomechanical stability among CICPS, CPS and DTPSTMandanalyze the relationship between bone cement volume and the maximum pullout strength(Fmax) to optimize the volume solution.3) To discuss the safety and efficacy of CICPS by clinical experiments so as toprovide sufficient theretical basis for wide clinical application of CICPS.Methods: 1) Experiments in vitro: Shear stress test is conducted on CICPS and CPS to comparemechanical properties. Four groups of CICPS and DTPSTM, injected with1ml,2ml,3ml,5ml volumes of bone cement, together with CPS are planted in OP biomechanical testblock (BTB). X ray, CT scan and the maximum pullout strength test are conducted tocompare the biomechanical stability among the three screws. The relationship betweenFmax and the volume of bone cement are also analyzed.2) Clinical experiment: From2010to2012,24OP cases have been used CICPS toenhance internal fixation. Complications including bone cement leakage, blockage andinfection are recorded. Visual analog scale (VAS), oswestry disability index (ODI), X-rayand CT (over six months) is followed-up after surgery. The data of clinical manifestation,function of lower limbs, screw pull-out and bone fusion is analyzed. In addition, specialmeasurements were given to spondylolisthesis. The Taillard index (the degree of slip), theslip angle and the disc height were measured on the lateral X-ray view pre-operationallyand follow-up so as to evaluate vertebral reduction and maintenance.Results:1) Experiments in vitro①Shear stress test: The shear stress of CICPS is significantly less than CPS but it canmeet the spinal fixation requirement.②Maximum pullout strength test: In OP biomechanical tests block, the Fmax ofCICPS and DTPSTMis significantly greater than CPS. A larger bone cement volumecaused a greater strength in CICPS and DTPSTM. There is a highly positive correlation.When bone cement volume is1ml,2ml,3ml, the stability of CICPS is greater thanDTPSTM. Bone cement is distributed through all the three side holes of CICPS. No rearleakage is observed in BTB. Bone cement in the bone trabeculae forms the compound of“screw-bone cement-bone trabeculae”, which fix the screw in the vertebral body. InDTPSTM, bone cement is mainly distributed from the proximal side holes, and the distalside hole is less. When bone cement volume is5ml, the stability of DTPSTMis greater thanCICPS. And the dispersion morphology of bone cement is similar between CICPS andDTPSTM.2) Clinical experimentThe average follow-up time is about7.0months (rang3-23months) with the minimum of three months. Compare to the data before surgery, the evaluation of VAS and ODI isbetter after surgery. Pain and lower limb function change for the better. No bone cementleakage is observed; four cases occure spinal sacral veins leakage without nerve symptoms.All patients have no complications such as infection and embolization. On the lastfollow-up imaging examinations, all pedicle screws do not happen to loose or pull out, andthe pedicle screw fixation system is in position. Six month after the surgery, bone infusionrate reaches100%. The cases of spondylolisthesis, post-operatively the average slippercentage (Taillard index), slip angle are significantly decreased and the disc height issignificantly improved compared to those of pre-operation.Conclusion:1) CICPS can enhance stability in osteoporosis vertebral, significantly better thanCPS and similar products. When the bone cement usage is1ml, CICPS can achievesatisfactory effect on enhancing fixation. By reducing the amount of bone cement, CICPSfinally achieves the object of decreasing the leakage risk.2) Hollow design makes CICPS shear stress lower than CPS, but enough to meet theclinical demand.3) In osteoporosis vertebral, bone cement is distributed in the front of screw, whichcan effectively avoid the complications such as, damaging of burning, leakage andcompressing the nerves.4) CICPS clinical result is favorable and the recovery is desirable. No screw loosingor pull-out case is observed. CICPS is considered as a safe, effective, and easily-operatedinternal fixation option for OP patients.更多还原