聚甲基丙烯酸甲酯强化对骨质疏松椎弓根螺钉固定的生物力学作用

目的探讨聚甲基丙烯酸甲酯 (polymethylmethacrylate,PMMA)骨水泥强化椎弓根螺钉的方法和评价 PMMA强化骨质疏松椎弓根螺钉后的生物力学性质。方法 6具新鲜老年女性胸腰段骨质疏松脊柱标本 (T10～ L5),使用双能 X线骨密度吸收仪测试每个椎体的骨密度,随机取 16个椎体 (32侧椎弓根 ),一侧椎弓根拧入 CCD螺钉,测量最大旋入力偶矩后拔出螺钉作为正常对照组,用 PMMA骨水泥强化椎弓根螺钉作为修复固定组,行螺钉拔出试验;另一侧经导孔直接强化椎弓根螺钉后拔出作为强化固定组,记录三组螺钉的最大轴向拔出力。结果椎体平均骨密度为 (0.445± 0.019)g/cm2;螺钉最大旋入力偶矩为（ 0.525± 0.104） Nm;正常对照组螺钉最大轴向拔出力为 (271.5± 57.3)N;修复固定组为 (765.9± 130.7)N;强化固定组为 (845.7± 105.0)N。 PMMA骨水泥强化或修复骨质疏松椎弓根螺钉后最大抗压力明显高于强化前,差异有非常显著性意义 (P< 0.01)。结论 PMMA骨水泥强化骨质疏松椎弓根螺钉能显著增加螺钉在椎体内的稳固性。     

椎弓根骨水泥灌注螺钉再植入的临床应用

目的探讨椎弓根骨水泥灌注螺钉再植入技术对骨质疏松患者手术治疗的临床疗效。方法骨质疏松患者16例,平均63．8岁。采用椎弓根骨水泥灌注螺钉再植入的方法植入椎弓根螺钉121枚,观察椎弓根螺钉术中及术后的稳定性。结果16例患者均获得随访,随访时间8～36个月,平均18个月。16例均获得骨性愈合,愈合时间为4～6个月,X线片显示内固定物无松动、断裂或脱落,螺钉周围未见透亮线出现。结论经椎弓根向椎体、钉道灌注聚甲基丙烯酸甲酯骨水泥,固化椎体的同时,增加了椎弓根螺钉的把持力,能够满足骨质疏松患者脊椎后路固定手术对力学稳定的要求。     

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。     

骨水泥螺钉与可膨胀椎弓根螺钉治疗严重骨质疏松腰椎病手术的比较

[目的]对比可灌注椎弓根骨水泥螺钉与可膨胀椎弓根螺钉应用于严重骨质疏松老年患者腰椎退变疾病手术的临床效果。[方法]选择本院2012～2015老年腰椎退变疾病合并严重骨质疏松患者30例;完善术前X线片、CT及MRI检查后,15例行经皮可灌注骨水泥螺钉固定+Mis-TILF减压手术技术,另15例行可膨胀螺钉固定+Mis-TILF减压手术技术。分别记录术前、术后VAS评分、JOA评分以及椎弓根钉松动率并进行统计分析。[结果]所有患者均顺利手术,术中均未出现神经损伤、骨水泥渗漏。所有患者随访1年以上。VAS评分随术后时间延长而逐渐减小、JOA评分随术后时间延长而逐渐增加,不同时间点间的差异均有统计学意义(P0.05)。随访中均未见螺钉断钉、断棒现象。可灌注椎弓根骨水泥螺钉组所有患者椎弓根螺钉未见松动现象,可膨胀椎弓根螺钉组有2例患者椎弓根钉出现不同程度松动,占可膨胀螺钉组13.3%,两组椎弓根钉松动率差异有统计学意义。[结论]微创下中空可灌注骨水泥螺钉应用于老年严重骨质疏松患者,在术后恢复过程中效果更可靠,固定更牢固,不易松动,可为老年微创手术患者提供稳定有效的脊柱内固定。     

椎弓根螺钉骨水泥强化固定治疗腰椎退行性变的临床效果

目的 探讨椎弓根螺钉骨水泥强化固定治疗腰椎退行性变的临床效果.方法 对56例腰椎退行性变患者行椎弓根螺钉骨水泥强化固定、椎间植骨融合,术前测量拟固定椎体的骨密度,术中测量螺钉的最大旋入力偶矩后取出螺钉,钉道注入聚甲基丙烯酸甲酯（PMMA）3ml再次置入螺钉并测量螺钉的最大旋入力偶矩,椎体固定后减压并行椎体间植骨融合.结果 患者均获随访,时间6~24（14.4±3.6）个月,均未发生内固定物松动、断钉及断棒等并发症.影像学评估：骨水泥分布于钉道周围松质骨中无明显椎体外渗.末次随访时按改良Macnab标准评价临床疗效：优27例,良22例,可7例;椎弓根螺钉的最大旋入力偶矩经术中骨水泥强化固定后由（0.61±0.23）N·m增至（1.35±0.32） N·m,差异有统计学意义（P〈0.05）.结论椎弓根螺钉骨水泥强化固定治疗腰椎退行性变可以明显增强螺钉的稳定性.     

骨水泥强化椎弓根螺钉治疗胸腰椎骨质疏松性骨折伴后凸畸形的研究

目的观察骨水泥强化椎弓根螺钉治疗胸腰椎骨质疏松性骨折伴后凸畸形的临床疗效。方法随访2013年3月至2016年8月在我院采用骨水泥强化椎弓根螺钉治疗胸腰椎骨质疏松性骨折伴后凸畸形的52例患者,男10例,女42例,年龄55~84岁,平均70.5岁。通过PACS阅片软件测量术前、术后3个月及末次随访脊柱局部后凸Cobb角来观察后凸畸形矫正情况,通过比较术前及术后腰背部疼痛视觉模拟评分(visual analogue scale,VAS)、Oswestry功能障碍评分(oswestry disability index,ODI)评估患者生活质量。应用ASIA分级系统对神经功能进行评估。收集患者围手术期并发症及骨水泥相关并发症发生情况。结果 52例患者手术共458枚椎弓根螺钉置入了232个椎体中,骨水泥强化了282枚螺钉(61.6%)和146个椎体(62.9%),胸椎平均每个钉道使用骨水泥(2.03±0.52)mL,腰椎平均每个钉道使用骨水泥(2.43±0.88)mL。随访3~56个月,平均19.2个月。术前腰背部疼痛VAS评分为(6.54±1.26)分、ODI评分为(69.06±13.26)%、局部Cobb角为(23.88±13.73)°,末次随访腰背部疼痛VAS评分为(1.88±0.68)分、ODI评分为(20.74±5.91)%、局部Cobb角为(11.07±8.96)°,与术前相比明显改善,差异具有统计学意义(P0.001)。术前7例神经损害患者ASIA分级为C级2例、D级5例,术后提高至D级2例、E级5例。强化282枚螺钉中有1枚出现骨水泥向椎弓根内侧壁渗漏,经术中及时清除后未出现神经功能障碍加重;11枚发生骨水泥向椎体前方渗漏,13枚发生骨水泥渗漏进入椎间盘内,术后均无临床症状。458枚螺钉均无松动、断裂。结论骨水泥强化椎弓根螺钉治疗胸腰椎骨质疏松性骨折伴后凸畸形既提高了螺钉的稳定性,又矫正了后凸畸形。     

骨水泥强化椎弓根螺钉固定治疗老年退行性腰椎不稳的临床疗效分析

目的:探讨用聚甲基丙烯酸甲(polymethylmethacrylate,PMMA)骨水泥强化椎弓根螺钉内固定治疗老年退行性腰椎不稳的临床疗效.方法:回顾性分析2002年3月～2009年6月收治的23例老年腰椎退行性不稳患者的临床资料,其中:男6例,女17例;年龄62～77岁,平均71岁;均采用PMMA骨水泥强化椎弓根螺钉内固定、椎体间植骨融合治疗,术前测量待置人螺钉之椎体的骨密度,术中测量螺钉的最大旋入力偶矩;取出螺钉后经钉道注入3ml粘稠的PMMA,再拧入螺钉,10min后拧紧螺钉并测量螺钉的最大旋入力偶矩;减压后行植骨融合内固定.结果:所有患者随访7～24个月,平均17个月,腰腿痛治愈好转率达87%,无手术并发症发生.PMMA强化椎弓根螺钉后,螺钉的最大旋入力偶矩由0.591±0.213N·m增至1.332±0.377N·m,差异有显著性(P<0.01):影像学表现为骨水泥分布于钉道周嗣松质骨中,未出现椎体外渗漏.结论:骨水泥强化椎弓根螺钉内固定治疗老年退行性腰椎不稳能明显增强螺钉的稳定性;正确掌握进钉技术及螺钉强化技术是手术成功的关键.     

医用骨水泥在骨质疏松患者行椎弓根钉固定中的作用

目的：探讨应用骨水泥在骨质疏松患者行椎弓根钉同定术的临床效果和安全性。方法：对20例骨质疏松患者经骨水泥灌注后行椎弓根钉固定术，比较患者术后1周和复查时的X线片，观察内置物有无松动，骨水泥固定螺钉周围有无透亮线出现。并对复查患者行固定节段的CT扫描，观察螺钉周围有无透亮线出现。结果：18例(90％)患者获随访，平均随访时间18个月，X线片中均未发现内置物松动或脱出，固定节段植骨愈合良好．在骨水泥固定螺钉周围未发现有透亮线出现；CT扫描在螺钉周围也未发现透亮线出现。结论：对于骨质疏松患者．应用骨水泥对椎弓根钉固定进行加固可防止内置物松动脱出，有较好稳定脊柱的临床效果。但应注意手术技巧，确保没有骨水泥渗漏。     

通用型脊柱内固定系统椎弓根螺钉的生物力学测试

目的测试自行设计的通用型脊柱内固定系统(generalspinesystem,GSS)椎弓根螺钉以及SOCON和CCD螺钉置入正常成人椎体标本的最大轴向拔出力及最大旋入力矩,评价GSS螺钉对椎弓根的锚固作用。方法将27个正常成人腰椎椎体标本随机分为3组,每组9个椎体(18侧椎弓根),分别置入GSS、SOCON和CCD椎弓根螺钉,行螺钉拔出试验,测试并记录螺钉的最大旋入力矩和最大轴向拔出力。结果三组螺钉的最大旋入力矩分别为(1.83±0.27)Nm、(2.09±0.51)Nm和(1.66±0.34)Nm,最大轴向拔出力分别为(1131.0±255.4)N、(1034.0±262.3)N和(886.1±152.9)N。GSS螺钉最大轴向拔出力最大,且与CCD螺钉相比差异有非常显著性意义(P<0.01)。结论GSS螺钉具有很强的椎弓根锚固作用。     

临时单侧经皮椎弓根螺钉撑开联合PKP治疗椎体后壁破裂骨质疏松椎体压缩骨折

目的:评价临时单侧椎弓根螺钉撑开结合椎体后凸成形术治疗伴椎体后壁破裂的骨质疏松椎体压缩骨折的疗效。方法:选择我院2012年1月~2014年12月收治的35例单节段伴椎体后壁破裂且无神经功能损害的骨质疏松椎体压缩骨折患者,女性30例,男性5例,年龄55~80岁(平均65.5±7.13岁)。损伤节段从T11~L4共35个骨折椎体。均采用术中临时单侧椎弓根螺钉撑开,结合球囊扩张椎体后凸成形术治疗,随访观察治疗效果。影像学观测术前、术后伤椎Cobb角及椎体高度变化情况,采用视觉模拟评分(vasual analogue scale,VAS)、Oswestry功能障碍指数(Oswestry disability index,ODI)评价患者手术前后的疼痛和功能状况以判断临床疗效。结果:手术时间平均78.33±13.94min,每个病椎注入骨水泥量平均5.10±1.13ml。术中出血平均18.80±5.29ml。术中有2个椎体出现骨水泥渗漏,渗漏方向为椎体侧方1例,椎间隙1例,均无椎管内渗漏。术后随访12~24个月(平均15±5.50个月)。术前伤椎Cobb角为16.25°±6.50°,伤椎前缘高度为0.62±0.17,伤椎中央高度为0.63±0.09;末次随访时分别为12.26°±5.14°,0.71±0.11和0.70±0.14,较术前明显改善(P0.05);术前VAS为8.03±1.61分,ODI为0.73±0.17;末次随访时分别为0.60±0.74分和0.10±0.04,较术前明显改善(P0.05)。结论:伴有椎体后壁骨折的骨质疏松椎体压缩骨折,应用经皮邻椎临时椎弓根螺钉撑开结合椎体后凸成形术治疗,恢复椎体高度满意,骨水泥渗漏发生率低,可获得良好的临床疗效。     

Comparative biomechanical analysis of an improved novel pedicle screw with sheath and bone cement

STUDY DESIGN: A human cadaveric biomechanical study of fixation strength of an improved novel pedicle screw (NPS) with cement and a conventional screw. OBJECTIVE: To clarify whether the NPS has adequate fixation strength without leakage in vertebrae with low bone quality. SUMMARY OF BACKGROUND DATA: The fixation strength of pedicle screws decreases in frail spines of elderly osteoporotic patients. Augmentation of screw fixation with bone cement must be balanced against increased difficulty of screw removal and risk of cement leakage. We developed the NPS consisting of an internal screw and an outer sheath to mitigate the disadvantages of cement augmentation. METHODS: The T12 and L1 vertebrae obtained from 18 formalin preserved cadavers (11 males and 7 females; mean age, 82.7 y) were used. The mean bone mineral density was 0.39 +/- 0.14 g/cm2. The NPS was inserted into one pedicle of each vertebra and the control screw, a Compact CD2 screw, was inserted into the contralateral pedicle. Both screws were 6mm in diameter and 40 mm in length. Pull-out tests were performed at a crosshead speed of 10 mm/min. Cyclic loading tests were performed with a maximum 250 N load at 2 Hz until 30,000 cycles. RESULTS: Cement leakage did not occur in any of the specimens tested. The mean maximum force at pull-out was 760 +/- 344 N for the NPS and 346 +/- 172N for the control screw (P < 0.01). Loosening of 50% of the screws was observed after 17,000 cycles of the NPS and after 30 cycles of the control screw. The hazard ratio of loosening was 19.6 (95% confidence interval 19.3-19.9) (P < 0.001). CONCLUSIONS: The NPS showed a significantly higher mechanical strength than the control screw in both pull-out tests and cyclic loading tests. The NPS showed more than adequate strength without cement leakage.     

两种长度的颈椎椎弓根螺钉与侧块螺钉拔出试验比较

目的:比较两种长度的颈椎椎弓根螺钉和侧块螺钉的抗拔出力,探讨颈椎经椎弓根短螺钉固定的可行性。方法:5具C3~C5共15节新鲜颈椎标本,用长度为28mm和20mm的皮质骨螺钉分别置入椎弓根,并用20mm的螺钉行侧块双皮质固定,螺钉进入侧块深度约14mm。行拔出试验,比较螺钉的最大轴向拔出力。结果:椎弓根长螺钉的最大拔出力为650N,椎弓根短螺钉为585N,两者比较无显著性差异(P>0.01);侧块螺钉的最大拔出力为360N,与椎弓根短螺钉比较有显著性差异(P<0.0001)。结论:颈椎椎弓根短螺钉固定可提供足够的稳定性,其安全性相对较高。     

Hydroxyapatite-coating of pedicle screws improves resistance against pull-out force in the osteoporotic canine lumbar spine model: a pilot study.

BACKGROUND CONTEXT: In patients with spinal osteoporosis, the early achievement and maintenance of a biological bond between the pedicle screw and bone is important to avoid screw loosening complications. There are few reports of in vivo investigations involving biomechanical and histological evaluations in the osteoporotic spine. PURPOSE: To evaluate the effect of hydroxyapatite (HA)-coating on the pedicle screw in the osteoporotic lumbar spine and to investigate the relationship between resistance against the screw pull-out force and bone mineral density (BMD) of the vertebral body. STUDY DESIGN/SETTING: Mechanical and pathological investigations in the lumbar spine. METHODS: Two 24-month-old female beagle dogs were fed a calcium-free dog chow for 6 months after ovariectomy (OVX). BMD (in g/cm2) was measured by dual energy X-ray absorptiometry at pre-OVX and 6 months after OVX. Pedicle screws were placed from L1 to L6 at 6 months after OVX. Twenty-four pure titanium cortical screws (Synthes, #401-114) were used as pedicle screws (Ti-PS). Of these, 12 screws had HA-coating (HA-PS). The HA-PS screws were inserted into the right pedicles and the Ti-PS were inserted into the left pedicles. Ten days after this procedure, the lumbar spines were removed en bloc for screw pull-out testing and histological evaluation. RESULTS: The mean BMD value of the lumbar vertebrae 6 months after the OVX was 0.549+/-0.087 g/cm2, which was significantly less than the pre-OVX mean BMD of 0.603+/-0.092 g/cm2 (p < 0.001). The mean resistance against the pull-out force for the HA-PS was significantly greater at 165.6+/-26.5N than in the Ti-PS (103.1+/-30.2N, p < .001). The histological sections in the HA-PS clearly revealed new bone bonding with the apatite coating but only fibrous tissue bonding in the Ti-PS. CONCLUSIONS: The results of this study showed that the resistance to the pull-out force of HA-PS is 1.6 times that of Ti-PS. Furthermore, HA-PS has superior biological bonding to the surrounding bone, as early as 10 days after surgery in this osteoporotic spine model. Thus, in patients with osteoporosis, coating of the pedicle screw with HA may provide better stability and bonding between the pedicle screw and bone in the early postoperative period.     

不同椎弓根螺钉固定及骨水泥强化方法在骨质疏松骶骨上锚定强度的比较

目的:通过比较不同椎弓根螺钉固定及骨水泥强化方法在骨质疏松骶骨上的锚定强度,探讨骶骨椎弓根螺钉松动后的理想补救技术.方法:应用11具成人新鲜骶骨标本,经骨密度测试确认为骨质疏松后,在同一骶骨标本上,依次建立5种骶骨螺钉固定模型,A组,单皮质椎弓根螺钉固定(左侧):B组,双皮质椎弓根螺钉固定(右侧);C组,PMMA钉道强化后单皮质椎弓根螺钉固定(建立于A组螺钉拔出后);D组,PMMA钉道强化后侧翼钉固定(右侧);E组,后凸成形技术支持下的PMMA强化后侧翼钉固定(左侧).应用MTS材料测试机进行轴向拔出测试,记录各种骶骨螺钉固定技术的最大拔出力并进行比较.结果:11具标本的骨密度为0.55～0.79g,cm~2,平均0.71±0.08g/cm~2.A～E组最大拔出力分别为508±128N、685±126N、846±230N、543±121N和702±144N.A组与D组间无显著性差异(P>0.05),且均显著低于B、C和E组(P<0.05);B组与E组间无显著性差异(P>0.05),但两组的拔出力均显著低于C组(P<0.05).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更高的锚定强度.骶骨椎弓根钉一旦发生松动,PMMA钉道强化和后凸成形技术支持下的PMMA强化后的侧翼钉固定均可成为理想的补救手段.     

Biomechanical comparison of anatomic trajectory pedicle screw versus injectable calcium sulfate graft-augmented pedicle screw for salvage in cadaveric thoracic bone

Many salvage options for failed thoracic pedicle screws exist including the use of a different trajectory or the augmentation of the screw with polymethylmethacrylate cement. Although polymethylmethacrylate immediately increases the construct stiffness and the pull-out strength, it may cause bone necrosis, toxin relaxation, and/or neural injury. On the other hand, calcium sulfate bone grafts have a high potential for biologic incorporation and no thermal damage effect. In the current study, polyaxial pedicle screws were first inserted with a straightforward approach on both sides in 17 fresh human cadaveric thoracic vertebrae. The maximal insertion torque for each screw was measured and then the pull-out strengths were recorded. Afterward, these pedicle screws were randomly assigned to be replaced either by graft augmentation or by anatomic trajectory technique for salvage. The graft-augmented screws were placed using the previous holes. The maximum insertional torque for each anatomic trajectory screw was measured. Finally, the pull-out strengths of the revision screws were recorded. The mean maximum insertional torque decreased with the anatomic trajectory salvage technique when compared with the straightforward approach, 0.23 versus 0.38 Nm, respectively (P=0.003). The anatomic trajectory revision resulted in decreased pull-out strength when compared with the pull-out strength of the straightforward technique, 297 versus 469 N, respectively (P=0.003).The calcium sulfate graft augmentation increased the pull-out strength when compared with the pull-out strength of the straightforward technique, 680 versus 477 N, respectively (P=0.017). The mean pull-out strength ratio of revised screw to original was 0.71 for anatomic trajectory and 1.8 for graft-augmented screws, a statistically significant difference (P=0.002).     

Efficacy of novel-concept pedicle screw fixation augmented with calcium phosphate cement in the osteoporotic spine

Pedicle screw instrumentation has become increasingly popular for rigid internal stabilization of the thoracolumbar spine. However, when pedicle screws are used in elderly osteoporotic patients, the screw–bone interface is stripped easily. Therefore, the risk of screw loosening and backing-out after surgery has increased. The purpose of this study was to evaluate the efficacy of the novel-concept pedicle screw fixation augmented with calcium phosphate cement (CPC) in the osteoporotic spine. The novel-concept screw has the same shape as the ordinary screw, but it is hollow and fabricated with 20 small holes (1.3mm in diameter) leading to the hollow part on the bottom of the thread. Fifteen embalmed cadaveric lumbar vertebrae were instrumented with two types of pedicle screw (the ordinary screw and the novel-concept screw) in each pedicle. Only the novel-concept screws were augmented with CPC after insertion. Seven days later, axial pull-out testing was performed at a crosshead speed of 10mm/min. The mean maximal pull-out strength of the ordinary screws was 258N, and that of the novel concept screws was 637N. These results suggest that the novel-concept screw augmented with CPC can be useful for pedicle screw fixation of the osteoporotic spine.     

Cervical pedicle screws vs. lateral mass screws: uniplanar fatigue analysis and residual pullout strengths

BACKGROUND CONTEXT: Although successful clinical use of cervical pedicle screws has been reported, anatomical studies have shown the possibility for serious iatrogenic injury. However, there are only a limited number of reports on the biomechanical properties of these screws which evaluate the potential benefits of their application. PURPOSE: To investigate if the pull-out strengths after cyclic uniplanar loading of cervical pedicle screws are superior to lateral mass screws. STUDY DESIGN: An in vitro biomechanical study. METHODS: Twenty fresh-frozen disarticulated human vertebrae (C3-C7) were randomized to receive both a 3.5 mm cervical pedicle screw and lateral mass screw. The screws were cyclically loaded 200 times in the sagittal plane. The amount of displacement was recorded every 50 cycles. After cyclical loading, the screws were pulled and tensile load to failure was recorded. Bone density was measured in each specimen and maximum screw insertion torque was recorded for each screw. RESULTS: During loading the two screw types showed similar stability initially, however the lateral mass screws rapidly loosened compared to the pedicle screws. The rate of loosening in the lateral mass screws was widely variable, while the performance of the pedicle screws was very consistent. The pullout strengths were significantly higher for the cervical pedicle screws (1214 N vs. 332 N) and 40% failed by fracture of the pedicle rather than screw pullout. Pedicle screw pullout strengths correlated with both screw insertion torque and specimen bone density. CONCLUSIONS: Cervical pedicle screws demonstrated a significantly lower rate of loosening at the bone-screw interface, as well as higher strength after fatigue testing. These biomechanical strengths may justify their use in certain limited clinical applications.     

下颈椎后路3种固定技术的拔出强度研究

目的评价下颈椎后路侧块螺钉、椎弓根螺钉、经关节螺钉3种固定方法的拔出强度。方法6具新鲜颈椎尸体标本（C3～C7）,分别用侧块螺钉Roy-Camille法（LMS）、椎弓根螺钉（TPS）和经关节螺钉植入法（TAS）拧入螺钉,使用万能材料实验机,以100、200、300、400、500、600N分级加载,以18mm/min加载速度进行螺钉拔出实验,测试其最大拔出力、最大拔出能量。结果LMS最大拔出力为（426±38）N,最大拔出能量为（5.26±0.39）J;TPS最大拔出力为（502±42）N,最大拔出能量为（7.18±0.67）J;TAS最大拔出力为（482±40）N,最大拔出能量为（6.68±0.47）J。LMS的最大拔出力和最大拔出能量均小于TPS和TAS（P〈0.05）,而TPS和TAS之间相近,差异无统计学意义（P〉0.05）。结论经关节螺钉拔出强度优于侧块螺钉,而椎弓根螺钉拔出强度最大。     

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。