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《中国矫形外科杂志》2020,(6):572-573
[目的]应用一种中间锁定两端滑动的椎弓根钉棒系统治疗生长发育期特发性脊柱侧弯。[方法]采用中间锁定两端滑动椎弓根螺钉系统治疗生长发育期特发性脊柱侧弯66例。手术在全麻下进行,侧弯主弯区(顶椎)两个椎体两侧置入4枚椎弓根钉,在顶椎两端上下椎体每间隔1个椎体置入滑动钉,平均每一侧置入4~6枚椎弓根螺钉。选择2根矫形合金棒置入椎弓根钉尾端,两端多出上下末位钉约3 cm,留出纵向滑移的空间,折成生理弧度,H型套帽固定尾部,然后慢慢旋转双棒,矫正脊柱畸形,将双棒锁紧固定于主弯区顶椎4枚钉上,在双侧矫形棒上放置横向滑动或锁定连杆,并锁紧,框架结构固定完毕。[结果] 66例特发性脊柱侧弯术前Cobb角(53.16±3.44)°,术后为(8.23±2.01)°,手术矫形效果满意。术前Cobb角≤50°患者矫正率为85%,术后随访1~6年,滑动区域内螺钉随脊柱纵向生长而伴发的生长性滑移距离1.5~3 cm,全部患者随访未见断钉、断棒和神经损伤等严重并发症。[结论]中间锁定两端滑动的椎弓根钉棒系统治疗生长发育期特发性脊柱侧弯过程中不影响患者正常发育且固定牢固。 相似文献
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《中国矫形外科杂志》2019,(9):833-836
[目的]评价胸椎半椎弓根钉置入固定方法的生物力学可靠性,为临床应用提供必要的安全参数。[方法]从尸体标本上应用半椎弓根置钉固定,对固定好的中上胸椎进行力学试验。采用应变电测试验技术。测试固定好的标本的抗压强度、扭矩与转角关系曲线、剪切强度和弯曲强度。[结果]当载荷从100 N逐渐加载到600 N的过程中,载荷与应变曲线呈正相关,表明模型的整体结构处于稳定状态。在中心加载时各试件加载至400 N时位移量在0.6~1.3 mm,说明位移变化不大。弯扭矩与试件两端之间相对扭转角呈线性关系,当扭转角达到10°时最大扭矩为12.40 N·m、弯矩为5.60 N·m。[结论]生物力学研究表明,在抗压强度、抗扭转时的剪切强度和弯曲强度上,半椎弓根钉置入技术在较粗规格的螺钉固定下,足够达到内固定及矫形的要求。 相似文献
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目的评价滑动椎弓根钉棒系统矫正青少年特发性脊柱侧凸的疗效。方法将椎弓根钉与矫形棒之间的连接设计为滑动式,使之可随脊柱生长而延长。手术治疗青少年特发性脊柱侧凸32例,对照术前和术后的脊柱侧凸cobb’s角并统计矫形率。结果 32例患者平均随访18个月,cobb’s角矫形平均39°(27°-53°)。患者术后身高平均增加3.2 cm,肺活量平均增加6%,有一例出现皮肤破溃。结论滑动椎弓根钉棒系统对青少年特发性脊柱侧凸有确切疗效,但其远期疗效还需要更进一步的随访来评价。 相似文献
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目的 :评估新型微创椎弓根钉-板内固定系统的生物力学强度。方法:根据美国材料测试协会(ASTM)标准构建单钉-棒测试组件,在万能材料试验机上分别对微创椎弓根钉-板、单向椎弓根钉-棒和万向椎弓根钉-棒组件进行生物力学强度测试。测试内容包括静态侧压测试和疲劳测试。在静态侧压测试中使用6套组件,记录组件屈服载荷、屈曲刚度以及失效模式。在疲劳测试中记录完成250万次循环负荷的最大应力数值。结果:微创椎弓根钉-板组件的屈服载荷和屈曲刚度显著低于单向椎弓根钉-棒组件(834.6±74.5N vs 1087.7±59.0N,218.1±22.4N vs 300.0±14.9N,P0.001)。微创椎弓根钉板组件的屈服载荷与万向椎弓根钉-棒组件比较无显著性差异(834.6±74.5N vs 762.8±88.6N,P=0.118);而钉-板组件的刚度显著低于万向钉-棒组件(218.1±22.4N/mm vs 389.5±37.2N/mm,P0.001)。单向椎弓根钉-棒组件的失败模式为连接棒发生塑性形变,万向椎弓根钉-棒组件为"球窝偶联"结构失效,微创椎弓根钉-板组件为钛板的塑性形变和钉-板连接部位失效。在250万次动态侧压疲劳测试中,单向椎弓根钉-棒组件、微创椎弓根钉-板组件和万向椎弓根钉-棒组件分别在450N、450N和350N循环载荷下完成测试。结论:新型微创椎弓根钉-板内固定系统可耐受250万次450N循环载荷作用,同时具有高屈服载荷和低屈曲刚度的特点。 相似文献
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【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。 相似文献
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目的测试新型上胸椎椎弓根钉内固定系统的生物力学性能。方法采用国际通用标准ASTM F543-2013及ASTM F1717-2013测试新型上胸椎椎弓根钉内固定系统的生物力学性能,进行单轴钉置入及拔出试验,万向钉压缩试验。并与常用颈胸椎椎弓根钉棒系统(常用组)及强生椎弓根钉棒系统(强生组)进行比较。结果试验组置入力矩低于常用组,拔出力小于常用组,差异有统计学意义(P0.05)。试验组屈服力大于强生组,但小于常用组,差异有统计学意义(P0.05)。试验组屈服刚度大于强生组,弹性位移、屈服位移小于强生组,但与常用组比较差异无统计学意义(P0.05)。试验组动态试验加载力最大值81 N为强生组的屈服力,反复加载后未损坏,故动态测试结果优于强生组。常用组动态试验加载力最大值110.9 N为试验组的屈服力,试验组与常用组反复加载后均未损坏,故动态试验结果接近。结论若上胸椎不稳但胸廓完整,新型上胸椎椎弓根钉内固定系统的生物力学性能可以满足临床的需要,提供即刻稳定性。 相似文献
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[目的]比较膨胀式椎弓根螺钉(expansive pedicle screw,EPS)与骨水泥(polymethylmethacrylate,PM-MA)强化方法在体外增强螺钉稳定性的效果,并观察各方法中的钉道界面情况.[方法]45个新鲜成年绵羊腰椎随机分为3组.CPS组:直接拧入普通椎弓根螺钉;PMMA-PS组:向钉道内注入PMMA后拧入普通椎弓根螺钉;EPS组:直接拧入EPS.24 h后,对所有标本进行轴向拔出实验、X线和micro-CT检查.[结果]EPS组和PMMA-PS组中螺钉的稳定性均显著强于CPS组(P<0.05),而EPS组和PMMA-PS组之间的差异无统计学意义(P>0.05).X线检查示各组中螺钉位置良好.CPS组中骨组织包裹螺钉,形成"螺钉-骨质"界面;PMMA-PS组中,PMMA包裹螺钉,阻碍了螺钉与骨质的接触,形成了"螺钉-PMMA-骨质"界面;EPS组中,骨小梁直接包裹螺钉,形成"螺钉-骨质"界面.螺钉的前端明显膨胀,形成一个"爪状"结构.螺钉前端胀开的两翼挤压周围骨质,使膨胀部分周围的骨质较非膨胀部分更加致密.[结论]EPS可以显著提高螺钉的稳定性,其效果与目前临床上常用的PMMA强化方法接近.同时,EPS可以有效的避免因增加螺钉直径和使用PMMA可能带来的椎弓根骨折和渗漏、压迫等风险.另外,EPS的置入并不增加手术时间和手术创伤.作为一种有效、安全和操作简便的方法,EPS在临床上的广泛应用具有巨大的潜力. 相似文献
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目的 评价聚甲基丙烯酸甲酯(Polymethylmethacrylate,PMMA)修复颈椎前路椎体螺钉钉道的生物力学效果。方法 防腐成人颈椎标本(C3~7)共30个,分3组:正常骨密度组(A组)、骨质疏松组(B组),骨质疏松修复组(C组),各组10个标本,测试疲劳前后的最大轴向拔出力。A、B对照组椎体二侧钉孔均放置4 mm的椎体螺钉,随机选择一侧行即时最大拔出力实验,另一侧在疲劳实验(2 Hz,20 000次)后行最大拔出力实验。C组(实验前需进行螺钉拔松实验)注入PMMA 0.6~1.0 mL,并拧入螺钉,随机选择一侧进行即时和疲劳后最大拔出力实验。结果 A、B、C组即时拔出力明显高于疲劳后拔出力,差异具有统计学意义(P< 0.05),C组疲劳后与A组即时拔出力比较,差异无统计学意义(P >0.05),但高于B组即时拔出力,差异具有统计学意义(P< 0.05)。即时拔出力C组 >A组 >B组,差异均有统计学意义(P< 0.05)。疲劳后拔出力C组 >A组 >B组,差异均有统计学意义(P< 0.05)。PMMA注射后未发现钉道渗漏。结论 PMMA钉道修复能够明显增强椎体螺钉的即时稳定性和抗疲劳能力, 并且安全有效,适用于螺钉松动和拔出的修复固定。 相似文献
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Mark Moldavsky Kanaan Salloum Brandon Bucklen Saif Khalil Jwalant S Mehta 《Indian Journal of Orthopaedics》2016,50(2):177-182
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Poor screw-to-bone fixation is a clinical problem that can lead to screw loosening. Under-tapping (UT) the pedicle screw has been evaluated biomechanically in the past. The objective of the study was to determine if pedicle preparation with a sequential tapping technique will alter the screw-to-bone fixation strength using a stress relaxation testing loading protocol.Materials and Methods:
Three thoracolumbar calf spines were instrumented with pedicle screws that were either probed, UT, standard-tapped (ST), or sequential tapped to prepare the pedicle screw track and a stress relaxation protocol was used to determine pull-out strength. The maximum torque required for pedicle screw insertion and pull-out strength was reported. A one-way ANOVA and Tukeys post-hoc test were used to determine statistical significance.Results:
The pedicle screw insertion torques for the probed, UT, ST and sequentially tapped (SQT) techniques were 5.09 (±1.08) Nm, 5.39 (±1.61) Nm, 2.93 (±0.43) Nm, and 3.54 (±0.67) Nm, respectively. There is a significant difference between probed compared to ST (P ≤ 0.05), as well as UT compared to both ST and SQT (P ≤ 0.05). The pull-out strength for pedicle screws for the probed, UT, ST and SQT techniques was 2443 (±782) N, 2353(±918) N, 2474 (±521) N, and 2146 (±582) N, respectively, with no significant difference (P ≥ 0.05) between techniques.Conclusions:
The ST technique resulted in the highest pull-out strength while the SQT technique resulted in the lowest. However, there was no significant difference in the pull-out strength for the various preparation techniques and there was no correlation between insertion torque and pull-out strength. This suggests that other factors such as bone density may have a greater influence on pull-out strength. 相似文献15.
Objective: In pedicle screw fixation, the heads of monoaxial screws need to be directed in the same straight line to accommodate the rod placement by backing out during operation, which decreases the insertional torque and internal fixation strength. While polyaxial screws facilitate the assembly of the connecting rod, but its ball-in-cup locking mechanism reduces the static compressive bending yield strength as compared with monoaxial screws. Our study aimed to assess the mechanical performance of a modified pedicle screw.
Methods: In this study, the tail of the screw body of the modified pedicle screw was designed to be a cylindershaped structure that well matched the inner wall of the screw head and the screw head only rotated around the cyclinder. Monoaxial screws, modified screws and polyaxial screws were respectively assembled into 3 groups ofvertebrectomy models simulated by ultra high molecular weight polyethylene (UHMWPE) blocks. This model was developed according to a standard for destructive mechanical testing published by the American Society for Testing Materials (ASTM F1717-04). Each screw design had 6 subgroups, including 3 for static tension, load compression and torsion tests, and the rest for dynamic compression tests. In dynamic tests, the cyclic loads were 25%, 50%, and 75% of the compressive bending ultimate loads respectively. Yield load, yield ultimate load, yield stiffness, torsional stiffness, cycles to failure and modes of failure for the 3 types of screws were recorded. The results of modified screws were compared with those ofmonoaxial and polyaxial screws.
Results: In static tests, results of bending stiffness, yield load, yield torque and torsional stiffness indicated no significant differences between the modified and monoaxial screws (P〉0.05), but both differed significantly from those ofpolyaxial screws (P〈0.05). In dynamic compression tests, both modified and monoaxial screws showed failures that occurred at the insertion point of screw body into the UHMWPE block, while the polyaxial screw group showed screw body swung up and down the screw head because of loosening of the ball-in-cup mechanism.
Conclusions: The modified screw is well-designed and biomechanically improved. And it can provide sufficient stability for segment fixation as monoaxial screws. 相似文献
Methods: In this study, the tail of the screw body of the modified pedicle screw was designed to be a cylindershaped structure that well matched the inner wall of the screw head and the screw head only rotated around the cyclinder. Monoaxial screws, modified screws and polyaxial screws were respectively assembled into 3 groups ofvertebrectomy models simulated by ultra high molecular weight polyethylene (UHMWPE) blocks. This model was developed according to a standard for destructive mechanical testing published by the American Society for Testing Materials (ASTM F1717-04). Each screw design had 6 subgroups, including 3 for static tension, load compression and torsion tests, and the rest for dynamic compression tests. In dynamic tests, the cyclic loads were 25%, 50%, and 75% of the compressive bending ultimate loads respectively. Yield load, yield ultimate load, yield stiffness, torsional stiffness, cycles to failure and modes of failure for the 3 types of screws were recorded. The results of modified screws were compared with those ofmonoaxial and polyaxial screws.
Results: In static tests, results of bending stiffness, yield load, yield torque and torsional stiffness indicated no significant differences between the modified and monoaxial screws (P〉0.05), but both differed significantly from those ofpolyaxial screws (P〈0.05). In dynamic compression tests, both modified and monoaxial screws showed failures that occurred at the insertion point of screw body into the UHMWPE block, while the polyaxial screw group showed screw body swung up and down the screw head because of loosening of the ball-in-cup mechanism.
Conclusions: The modified screw is well-designed and biomechanically improved. And it can provide sufficient stability for segment fixation as monoaxial screws. 相似文献
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目的评价钉棒系统分别行颈椎侧块及椎弓根固定后的初始稳定性,为临床应用提供理论依据。方法取8具新鲜冷冻人体颈椎标本,切断C4、5棘上韧带、棘间韧带、双侧关节囊,制成C4、5后柱不稳损伤模型,每个标本分别行正常标本、双侧C4、5侧块及椎弓根固定标本三维运动范围测定。结果两种内固定组的三维运动范围均明显小于正常组,椎弓根固定组三维运动组小于侧块螺钉固定组,两组差异有统计学意义。结论在颈椎后柱损伤模型中,用钉棒系统分别行侧块及椎弓根固定后均能明显提高脊柱三维稳定性,椎弓根内固定稳定性优于侧块钉棒系统。 相似文献
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目的研究不同骨密度对椎弓根螺钉内固定早期稳定性的影响,为临床工作提供生物力学参考。方法取新鲜成年绵羊胸腰椎脊柱标本(T13-L2)36具,采用随机数字表法分为4组,分别为A(HCL脱钙0 h)、B(HCL脱钙2 h)、C(HCL脱钙4h)、D(HCL脱钙6h)组,每组9个。采用EXPERT-XL双能X线骨密度仪(Lunar公司)对四组脊柱椎体进行测量,依据骨密度的不同分为骨量正常组骨量减少组骨质疏松组严重骨质疏松组。4组均采用在T14-L2上置入椎弓根钉棒系统。以(300±105)N的载荷对4组模型进行250 000次循环4个方向(前屈、后伸、左侧弯、右侧弯)加载,比较4组模型的脊柱活动范围、螺钉的最大拔出力、轴向压缩刚度。结果疲劳试验后,A、B、C、D组脊柱的运动范围值(ROM)、轴向压缩刚度依次增大、螺钉的最大拔出依次减小,各组间差异有统计学意义(P0.05)。结论 1.脊柱骨密度越低,椎弓根固定后脊柱早期的稳定性越差。2.对于骨密度在骨质疏松范围内的患者不能行单纯椎弓根螺钉固定,而且在骨性愈合期间应减少脊柱的活动量。 相似文献