后凸成形骨水泥强化技术对骶骨钉固定强度的生物力学影响

目的评价后凸成形骨水泥(Polymethylmethacrylate,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,为骶骨钉松动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,并采用DEXA评价标本骨密度。在同一骶骨标本上,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,记录最大拔出力并比较。结果11具标本的平均骨密度为0.71±0.08g/cm2。A组的螺钉拔出力(508N)显著低于其他4种固定组(P0.05)。B组的螺钉拔出力(685N)与E组(702N)无显著差异(P0.05),但是,两者的拔出力均显著低于C和D组(P0.05)。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。     

磷酸钙骨水泥强化椎弓根螺钉固定的生物力学研究

目的:评价磷酸钙骨水泥(calciumphosphatecement,CPC)对椎弓根螺钉固定的强化作用。方法:在两组男性尸体椎骨的一侧直接置入椎弓根螺钉作为对照(对照侧),另一侧填入CPC后再置入螺钉作强化固定(强化侧),15min和12h后测定椎弓根螺钉的最大轴向拔出力(Fmax),然后用CPC重新固定12h后拔松的椎弓根螺钉并测得其Fmax。结果:强化侧Fmax和对照侧比较,15min后提高了55%,12h后提高了83%;重新固定后,两侧Fmax较固定前分别提高了54.2%和63.6%,差别有显著性意义(Wilcoxon's检验,P<0.01)。结论:磷酸钙骨水泥能强化椎弓根螺钉的固定。     

骨质疏松程度对骶骨椎弓根螺钉固定的生物力学影响

目的:评价骨质疏松程度对骶骨椎弓根螺钉固定强度的影响.方法:25具骨质疏松成人新鲜尸体骶骨标本,按尸体腰椎骨密度(BMD)值分为A组(n=9,BMD 0.70～0.79g/cm2)、B组(n=8,BMD 0.60～0.69异/cm2)和C组(n=8,BMD＜0.60g,cm2).在同一标本的S1左侧置入双皮质椎弓根螺钉,右侧置入单皮质椎弓根螺钉时用聚甲基丙烯酸甲酯(PMMA)骨水泥强化.4h后使用MTS实验机对螺钉尾部进行30～250N的头尾方向循环加载2000次后,测定椎弓根螺钉的下沉位移和轴向拔出力.2000次载荷中螺钉下沉超过2mm定义为锚定失败.结果:A组和B组螺钉均未出现锚定失败;C组双皮质椎弓根螺钉锚定失败6例(75%),PMMA强化单皮质椎弓根螺钉锚定失败5例(63%).A组双皮质螺钉固定的下沉位移和轴向最大拔出力与PMMA强化螺钉固定比较无显著性差异(P＞0.05);B组.PMMA强化螺钉固定的下沉位移显著低于双皮质螺钉固定,轴向最大拔出力显著高于双皮质固定(P＜0.05).A组双皮质螺钉固定和PMMA强化螺钉固定的下沉位移均显著低于B组(P＜0.05),A组双皮质螺钉同定的轴向最大拔出力显著高于B组(P＜0.05).A组PMMA强化螺钉固定的轴向最大拔出力与B组比较无显著性差异(P＞0.05).C组内同定失败病例中,PMMA强化螺钉固定的承载次数显著高于双皮质螺钉固定(P＜0.05).结论:BMD≥0.70g/cm2时双皮质骶骨椎弓根螺钉同定和PMMA强化单皮质骶骨椎弓根螺钉固定可获得同等的锚定强度,BMD值为0.60～0.69g/cm2时PMMA强化单皮质骶骨椎弓根螺钉同定的锚定强度显著高于双皮质螺钉固定,BMD值＜0.60g/cm2时两种锚定方式均容易导致早期松动.术前行腰椎BMD检查可指导选择骶骨螺钉同定方式.     

可注射磷酸钙骨水泥对不同骨质椎弓根螺钉的强化作用

目的评价不同骨质疏松程度条件下,可注射性磷酸钙骨水泥对椎弓根螺钉稳定性强化作用,为其应用于合并有骨质疏松症的患者脊柱手术提供力学理论基础。方法采用新鲜尸体脊柱标本,根据骨密度检测结果,按临床诊断标准分成骨质正常、骨量减少、骨质疏松和重度骨质疏松四个水平;然后,每个骨密度水平,分直接置入椎弓根螺钉（对照组）和用可注射性磷酸钙骨水泥强化钉道后置入椎弓根螺钉（钉道强化组）,各12枚,进行螺钉轴向拔出实验,测定最大拔出力、刚度和能量吸收值三项指标,进行组间的对比分析。结果骨密度水平从正常下降到重度疏松程度,最大拔出力、刚度、能量吸收值均随之下降,同种置钉方法组间存在显著性差异（P〈0.05）。骨质疏松条件下钉道强化组最大拔出力、刚度、能量吸收值与骨量减少条件下对照组的比较,两者无显著性差异（P〉0.05）;但是,重度骨质疏松条件下钉道强化组的最大拔出力、刚度、能量吸收值均显著性低于骨量减少条件下对照组的（P〈0.05）。结论可注射性磷酸钙骨水泥强化钉道后可以提高椎弓根螺钉的稳定性,尤其是骨质疏松条件下经钉道强化后可以达到需要固定强度。     

骨水泥强化骨质疏松性椎体椎弓根螺钉的研究进展

目前椎弓根螺钉固定技术作为脊柱后路稳定的"金标准",已被广泛应用于临床.如果病人合并骨质疏松症,其内固定失败的风险将大大增加.骨水泥强化技术不仅能够显著提高骨质疏松性椎体术后骨质疏松椎体的稳定性,还能明显改善固定节段的周期性抗屈能力,为骨质疏松性椎体提供坚强、持久的内固定,从而有效重建脊柱的稳定性.但骨水泥强化技术也存在并发症,如骨水泥渗漏、加快邻近节段退变、增加骨折风险等.本文通过对骨水泥强化椎弓根螺钉固定的力学特性、骨水泥的选择、强化方式及近远期并发症等方面对骨水泥强化椎弓根螺钉固定技术进行综述.     

geneX骨水泥强化骨质疏松椎体椎弓根钉的生物力学研究

目的评估骨质疏松情况下geneX骨水泥强化椎弓根钉的固定强度。方法应用微量注射泵对30个新鲜小牛腰椎标本注射稀盐酸建立骨质疏松椎体模型。60个椎弓根分为四组:geneX骨水泥组,硫酸钙骨水泥(CSC)组,聚甲基丙烯酸甲酯骨水泥(PMMA)组,对照组。随机选择一侧注射2.5 ml骨水泥,然后置入螺钉;另一侧行正常螺钉固定对照,应用材料试验机进行轴向拔出力测试,记录各组的轴向最大拔出力和能量吸收值并进行比较。结果 geneX组与CSC组两组拔出力及能量吸收值比较,差异无统计学意义(P>0.05),两组均显著低于PMMA组(P<0.05),两组均显著高于对照组(P<0.05)。结论 geneX骨水泥强化椎弓根钉可显著提高椎弓根固定强度,geneX骨水泥可用作椎弓根强化螺钉的填充材料。     

磷酸钙骨水泥强化椎弓根螺钉对骨质疏松性椎体骨折的临床意义

目的 :评价磷酸钙骨水泥 (calciumphosphatecement ,CPC)强化和修复椎弓根螺钉的生物力学效果。方法 :6具新鲜老人骨质疏松的脊柱标本 ,从T11～L4 共 36个椎体 ,随机选取其中 32个 ,分为 4组 ,每组 8个。A组 :随机选择一侧椎弓根放置直径为 6 .5mm的椎弓根螺钉 ,另一侧以直径为 3.5mm的钻头导孔。向两侧椎弓根孔道注入配制好的磷酸钙骨水泥 (CPC) 3～ 5ml ,体温下 ( 37℃ )放置 2 4h后 ,再行前述拔出实验。B组 :应用PMMA进行修复和强化 ,作为对照 ,操作方法同A组。C组 :植入椎弓根螺钉 ,添加或不添加CPC ,进行周期抗屈实验。D组 :相同方法 ,应用PMMA作为对照。结果 :CPC骨水泥强化组和修复组拔出力明显高于对照组 ,差异有显著性意义 (P <0 .0 5)。结论 :在植入椎弓根螺钉时添加具有生物活性的磷酸钙 (CPC)骨水泥可显著提高其初始稳定性     

重度骨质疏松人工骨模块中不同剂量聚甲基丙烯酸甲酯强化椎弓根螺钉稳定性的比较

目的比较重度骨质疏松人工骨模块中不同剂量聚甲基丙烯酸甲酯(PMMA)强化椎弓根螺钉的稳定性,分析螺钉稳定性与PMMA剂量间的相关关系。方法将48块重度骨质疏松模块随机分为A~F 6个实验组(n=8),A组不注射PMMA,B~F组分别向钉道内注入1.0、2.0、3.0、4.0、5.0 m L PMMA后,各组拧入椎弓根螺钉,记录最大拧入力矩(T_(max))。待骨水泥硬化后进行X线检查,观察螺钉周围骨水泥的分布情况;随后进行力学实验,测量最大轴向拔出力(Fmax)并观察模块的破坏情况。结果 B~F组螺钉被PMMA严密包绕,B~F组螺钉周围PMMA的范围逐渐增加。与A组相比,B~F组的T_(max)均有显著提高。B组和C组、C组与E组之间T_(max)的差异具有统计学意义(P0.05),其余任何2组的T_(max)之间差异均无统计学意义(P0.05)。与A组相比,B~F组的Fmax均有显著提高。B组和C组、C组和D组、E组和F组的Fmax之间差异均无统计学意义(P0.05),其余任何2组的T_(max)之间差异均有统计学意义(P0.05)。T_(max)、Fmax、PMMA剂量三者之间均存在正相关关系。螺钉拔出后,A~F组模块的破坏程度逐渐增加。结论 PMMA可以显著提高重度骨质疏松人工骨模块中椎弓根螺钉的稳定性,螺钉的稳定性与PMMA剂量存在正相关关系。本研究中注射4 m L PMMA可以作为重度骨质疏松条件下合适的选择。     

骨水泥强化椎弓根螺钉固定的研究进展

椎弓根螺钉固定技术是脊柱后路固定的标准技术,但在骨质疏松情况下固定易松动失效,常需要行骨水泥强化以提高固定效果.本文简要介绍了疏松性椎骨骨-钉界面生物力学、骨水泥强化固定的方法和材料.并指出强化固定的指征和可吸收材料在骨质疏松性骨质强化巾的替代过程及其强度可能是值得期待的研究方向.     

直入式注入PMMA骨水泥强化椎弓根钉内固定生物力学研究

【摘要】 目的 分析直入式骨水泥注入椎体强化方法在体外提高螺钉稳定性的效果。方法采用新鲜尸体脊柱标本共24个椎体,一侧椎弓根采用直入式注入PMMA骨水泥强化椎弓根钉固定作(试验组),另一侧椎弓根采用常规椎弓根螺钉固定(对照组),两侧进行最大轴向拔出力试验、最大旋出力矩试验、周期抗屈试验生物力学测试,比较两组测试结果。结果〓骨水泥强化组中螺钉的稳定性均显著强于单纯常规椎弓根螺钉组(P < 0.05)。结论〓应用PMMA行椎体强化椎弓根钉固定有利于增强对椎弓根钉的把持力,可有效防止椎弓根钉的松动及脱落,具有良好的临床效果。     

Polymethylmethacrylate augmentation of the pedicle screw: the cement distribution in the vertebral body

Many studies have proven that the polymethylmethacrylate (PMMA) augmentation of the pedicle screw can significantly increase stiffness and strength of spinal fixation. Some major complications have also been reported. However, there are no reports discussing cement distribution and its morphology in the osteoporotic vertebral body, which is critical in the analysis of the biomechanical strength of the pedicle screw and the risk of cement leakage after pedicle screw augmentation. In this study, we used computed tomography (CT) to evaluate the cement distribution in the osteoporotic vertebral body after PMMA augmentation of a pedicle screw and to analyze the factors leading to cement leakage. Two groups of patients were studied. Group A consisted 25 osteoporotic patients (mean age of 73 years) with spinal instrumentation who had a total of 145 pedicle screws and cement augmentation with biopsy needles. Group B consisted of 23 osteoporotic patients (mean age of 74.6 years) with spinal instrumentation who had a total of 125 cannulated pedicle screws with cement augmentation. All patients had CT evaluation of the cement distribution in the vertebral body after the surgery. The cement distribution in the vertebrae was divided into four zones in the axial CT view: anterior one-third, middle third, and posterior third of vertebral body, and the pedicle. The morphology of the cement distribution around the pedicle screw was defined as scattered type or concentrate type. The leakage pattern was divided to anterior–lateral, posterior–lateral, and canal leakage. The correlations among bone mineral density (BMD), the cement leakage rate, and cement distribution morphology were also analyzed. The results showed that most augmented pedicle screws had cement extension into three of the four zones of the vertebral body (66.3%), followed by two zones (20%), all four zones (11.5%), and only one zone (2.2%). Overall, 123 screws (84.8%) in Group A and 108 screws (86.4%) in Group B had cement concentrate type distribution. The cement leakage rate in Group A is 18.3% and 13.6% in Group B. Patients with a BMD <0.6 g/cm² had significantly higher rates of cement leakage and tended toward a scattered cement distribution. There was only one patient who had a symptomatic leakage (sciatica) in Group B. We concluded that the cement distribution after pedicle screw augmentation with biopsy needle or cannulated screw technique was mostly localized in three zones of the vertebral body, and patients with lower BMD had a higher risk of cement leakage and scattered cement distribution.     

骨质疏松尸体腰椎中膨胀式椎弓根螺钉与骨水泥强化椎弓根螺钉固定稳定性的比较研究

【摘要】 目的：比较骨质疏松尸体腰椎膨胀式椎弓根螺钉（expansive pedicle screw,EPS）固定与骨水泥强化椎弓根螺钉（polymethylmethacrylate-augmented pedicle screw,PMMA-PS）固定的稳定性。方法：16个腰椎标本取自4具新鲜尸体的脊柱（L1~L4）。年龄51~78岁,平均63岁,其中女性3具,男性1具。所有标本经X线检查排除畸形、骨折等病变,其中1个腰椎因严重畸形被剔除。测量各椎体的骨密度值（bone mineral density,BMD）后,将15个椎体随机分为3组。采用相同方法制备钉道,普通椎弓根螺钉（CPS）组直接置入CPS;PMMA-PS组先向钉道内注入PMMA,再置入CPS;EPS组直接置入EPS。置钉后24h,对标本进行X线检查和CT扫描,观察螺钉位置及骨水泥分布情况;然后将椎体固定于MTS 858上,沿椎弓根螺钉的长轴方向以10mm/min的加载速度进行拔出实验,测量螺钉的最大轴向拔出力（the maximum pullout strength,Fmax）和能量吸收值（energy absorbed value,EAV）。结果：所有腰椎的BMD均小于0.8g/cm2,T值为-3.5~-2.5,均为骨质疏松椎体,3组之间BMD的差异无统计学意义（P>0.05）。X线检查和CT重建显示各组螺钉位置均良好,PMMA-PS组中未见PMMA渗漏现象;CPS组螺钉被周围的骨质直接包绕;PMMA-PS组螺钉被PMMA所包裹,PMMA存在于螺钉周围的骨质中,在椎体内形成了“纺锤样”结构;EPS组螺钉的前端在椎体内明显膨胀,形成了“爪状”结构。CPS组、PMMA-PS组和EPS组的Fmax分别为751.50±251.37N、1521.70±513.27N和1175.20±396.51N,PMMA-PS组和EPS组均显著高于CPS组（P<0.001,P=0.026）,而PMMA-PS组和EPS组之间的差异无统计学意义（P=0.064）。CPS组、PMMA-PS组和EPS组的EAV分别为1.47±0.51J、3.09±0.93J和2.46±0.69J,PMMA-PS组和EPS组均显著高于CPS组（P<0.001,P=0.005）,而PMMA-PS组和EPS组之间的差异无统计学意义（P=0.067）。结论：EPS可显著提高骨质疏松腰椎内椎弓根螺钉的稳定性,达到了与传统PMMA强化椎弓根螺钉接近的固定强度,具有良好的临床应用前景。     

骨质疏松绵羊腰椎膨胀式椎弓根螺钉与骨水泥强化椎弓根螺钉固定稳定性的动态比较研究

【摘要】 目的：比较骨质疏松绵羊腰椎膨胀式椎弓根螺钉（expansive pedicle screw,EPS）与骨水泥强化椎弓根螺钉（polymethylmethacrylate-augmented pedicle screw,PMMA-PS）固定的动态稳定性。方法：8只健康成年雌性绵羊,体重55.7±5.6kg,年龄5.5±0.7岁。行双侧卵巢切除术（去势手术）后1个月开始连续肌肉注射甲基强的松龙（0.45mg/kg/d）10个月,在建模前、激素注射结束后1个月（建模后）测量绵羊腰椎的骨密度（bone mineral density,BMD）,BMD显著下降（>25%）时为骨质疏松动物模型成功建立。建模后将每只骨质疏松绵羊腰椎（L1~L6）随机分为3组,每组2个腰椎。普通椎弓根螺钉（conventional pedicle screw,CPS）组,直接拧入CPS;PMMA-PS组,向钉道内注入聚甲基丙烯酸甲酯（PMMA,1.0ml）后拧入CPS;EPS组,直接拧入EPS。螺钉置入术后6周和12周各处死4只绵羊,取出腰椎,剔除标本周围软组织,自各椎间盘处离断,游离成单个椎体。每个腰椎随机选择一侧的螺钉行轴向拔出实验,将椎体固定于MTS 858生物材料实验机上,沿椎弓根螺钉长轴方向以5mm/min的加载速度进行轴向拔出实验,测量螺钉的最大轴向拔出力（the maximum pullout strength,Fmax）和能量吸收值（energy absorbed value,EAV）。结果：建模前、后绵羊腰椎的BMD分别为1.14±0.10g/cm2和0.83±0.07g/cm2,建模后BMD显著下降（P<0.05）,平均为27.2%（25.4%~28.9%）,骨质疏松绵羊模型成功建立。置钉术后6周EPS组和PMMA-PS组的Fmax分别为1252.13±203.51N和1426.38±235.75N,EAV分别为2.48±0.45J和2.84±0.55J,均显著高于CPS组（827.88±139.22N和1.66±0.30J）（P<0.05）;置钉术后12周EPS组和PMMA-PS组的Fmax分别为1518.88±256.81N和1472.75±248.65N,EAV分别为3.09±0.59J和2.95±0.60J,均显著高于CPS组（906.63±152.50N和1.80±0.35J）（P<0.05）;置钉术后6周、12周EPS组的Fmax和EAV与PMMA-PS组比较差异均无统计学意义(P>0.05)。置钉术后12周CPS组和PMMA-PS组的Fmax和EAV与同组置钉术后6周比较无显著性变化（P>0.05）,置钉术后12周EPS组的Fmax和EAV较同组置钉术后6周均有显著性提高（P<0.05）。结论：与CPS相比,EPS可显著提高螺钉在骨质疏松绵羊腰椎中的稳定性,并达到了与临床常用的PMMA-PS近似的固定效果。     

Biomechanical comparative study of the stability of injectable pedicle screws with different lateral holes augmented with different volumes of polymethylmethacrylate in osteoporotic lumbar vertebrae

Background Context

Polymethylmethacrylate (PMMA) is widely used for pedicle screw augmentation in osteoporosis. Until now, there had been no studies of the relationship between screw stability and the distribution and volume of PMMA.

两种不同方法提高椎弓根螺钉稳定性的体外生物力学研究

目的 比较膨胀式椎弓根螺钉(EPS)与骨水泥(PMMA)强化方法在体外提高螺钉稳定性的效果.方法 将60个新鲜成年绵羊腰椎随机分为三组.普通椎弓根螺钉组(CPS组):直接拧入普通椎弓根螺钉;PMMA-PS组:向钉道内注入PMMA(1.0 ml)后拧入CPS;EPS组:直接拧入EPS.24 h后对所有标本进行X线检查,随...     

Fenestrated pedicle screws for cement-augmented purchase in patients with bone softening: a review of 21 cases

Background  

This prospective mixed cohort study was designed to evaluate the middle- to long-term purchase of cement-augmented pedicular screws in patients with poor bone quality. The growing number of surgical procedures performed in the spine has highlighted the problem of screws loosening in patients with poor bone stock due to osteoporosis and/or tumors. Different methods of increasing screw purchase have been reported in the literature, including polymethylmethacrylate (PMMA) augmentation.     

Augmentation of (pedicle) screws with calcium apatite cement in patients with severe progressive osteoporotic spinal deformities: an innovative technique

Screw augmentation with calcium apatite cement (CAC) was used in seven patients with a progressive osteoporotic spinal deformity. Thirty-nine spinal segments (64 screws) were augmented: 15 anteriorly (three patients) and 24 posteriorly (five patients). Dorsally, hemilaminectomy was performed at the level of all augmented screws to rule out CAC leakage. Autogenous bone graft was applied in all patients to induce fusion. Screw augmentation failure occurred in only one patient: 1 of the 16 ventral augmented screws (5.5%) was still loose after the augmentation procedure. In three other patients, 4 out of 48 augmented dorsal screws (5.5%) showed CAC leakage at the pedicle corpus vertebra level. Pedicle wall damage was present at two levels, while at two other levels no wall damage was found during visualization. No CAC-related complications were observed perioperatively. No implant migration was observed, and fusion was observed in all cases at follow-up examination performed at a mean of 32 months after surgery. Received: 29 December 1999 Revised: 30 March 2000 Accepted: 7 April 2000     

Pedicle screw augmentation with bone cement enforced Vicryl mesh

Achieving sufficient mechanical purchase of pedicle screws in osteoporotic or previously instrumented bone is technically and biologically challenging. Techniques using different kinds of pedicle screws or methods of cement augmentation have been used to address this challenge, but are associated with difficult revisions and complications. The purpose of this biomechanical trial was to investigate the use of biocompatible textile materials in combination with bone cement to augment pullout strength of pedicle screws while reducing the risk of cement extrusion. Pedicle screws (6/40 mm) were either augmented with standard bone‐cement (Palacos LV + G) in one group (BC, n = 13) or with bone‐cement enforced by Vicryl mesh in another group (BCVM, n = 13) in osteoporosis‐like saw bone blocks. Pullout testing was subsequently performed. In a second experimental phase, similar experiments were performed using human cadaveric lumbar vertebrae (n = 10). In osteoporosis‐like saw bone blocks, a mean screw pullout force of 350 N (±125) was significantly higher with the Bone cement (BC) compared to bone‐cement enforced by Vicryl mesh (BCVM) technique with 240 N (±64) (p = 0.030). In human cadaveric lumbar vertebrae the mean screw pullout force was 784 ± 366 N with BC and not statistically different to BCVM with 757 ± 303 N (p = 0.836). Importantly, cement extrusion was only observed in the BC group (40%) and never with the BCVM technique. In vitro textile reinforcement of bone cement for pedicle screw augmentation successfully reduced cement extrusion compared to conventionally delivered bone cement. The mechanical strength of textile delivered cement constructs was more reproducible than standard cementing. © 2017 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 36:212–216, 2018.