颈椎钩椎关节融合器初始稳定性生物力学测试

目的测试颈椎钩椎关节融合器的初始稳定性。方法将20具山羊颈椎标本随机分为完整颈椎组、自体髂骨块植入组、钩椎关节融合器植入组、传统椎间融合器植入组四组,采用非破坏弹性法对山羊C_(3～4)节段进行过伸/过屈、左右侧屈以及轴向旋转活动范围(range of motion,ROM)测试。结果钩椎关节融合器组、零切迹融合器对照组在前屈、后伸、左右侧屈、轴向旋转维度上角位移与髂骨块植入组均差异有统计学意义(P0.05);钩椎关节融合器组和零切迹融合器对照组过伸/过屈ROM差异无统计学意义(P0.05),但钩椎关节融合器组左右侧屈ROM和左右旋转ROM略小于零切迹融合器对照组,差异有统计学意义(P0.05)。结论钩椎关节融合器在左右侧屈与轴向旋转方面稳定性略优于传统零切迹椎间融合器,在前屈/后伸方面与传统零切迹椎间融合器稳定性相当。     

不同椎板减压范围对BioFlex系统生物力学的影响

【摘要】 目的：利用有限元方法分析比较不同椎板减压范围对脊柱动态内固定BioFlex系统生物力学的影响。方法：利用Mimics 10.01三维重建软件建立正常L3～L5几何模型并利用ProE逆向工程软件建立BioFlex系统几何模型,按临床术式进行组装并导入ANSYS Workbench 14.0有限元分析软件进行前处理建立四种L3～L5三维有限元模型：完整状态L3～L5模型（INT组）,L4-L5椎板减压+1/2关节突切除+Bioflex模型（MF-BF组）,L4-L5椎板减压+全关节突切除+Bioflex模型（TF-BF组）,L4-L5椎板减压+髓核摘除+Bioflex模型（D-BF组）;在各模型L3椎体的上表面以及上关节突的关节面轴向予1200N载荷和8Nm、8Nm、6Nm、4Nm力矩下模拟人体腰椎正常生理轴向载荷、前屈、后伸、侧弯和扭转,L5椎体的下表面及下关节突表面各节点六个方向自由度完全固定。测量各模型固定节段和邻近节段的活动度以及邻近节段的髓核间应力与关节突应力,并进行分析比较。结果：椎板减压并置入动态内固定Bioflex系统后,脊柱固定节段的活动度各减压组较INT组明显减小（P＜0.05）,其中TF-BF组前屈活动度减小幅度最大达77.2%,MF-BF组后伸、侧弯、旋转活动度减小幅度最大分别达37.4%、67.2%、83.1%;邻近节段的活动度各减压组较INT组增大（P＜0.05）,其中MF-BF组前屈活动度增大幅度最大达22.9%,TF-BF组后伸、侧弯活动度增大幅度最大分别达18.2%、32.1%,DF-BF组旋转活动度增大幅度最大达13.8%。不同状态下固定节段及邻近节段活动度MF-BF组、TF-BF组及D-BF组间波动幅度不大,两两比较差异无统计学意义（P＞0.05）。邻近节段关节突应力及髓核间应力各减压组较INT组明显增大（P＜0.05）,其中TF-BF组关节突应力在后伸、旋转活动时增大幅度最大分别达81.6%、77.3%,DF-BF组关节突应力在侧弯活动时增大幅度最大达60.5%,DF-BF组髓核间应力在前屈活动时增大幅度最大达46.6%,MF-BF组髓核间应力在后伸、侧弯、旋转活动时增大幅度最大分别达11.8%、63.5%、51.3%;邻近节段的关节突应力与髓核间应力在不同状态下各减压组间波动幅度不大,两两比较差异无统计学意义（P＞0.05）。结论：置入BioFlex系统后脊柱固定节段的活动度明显减小,邻近节段的活动度增大,固定与邻近节段活动度不随椎板减压范围的改变而明显改变;邻近节段关节突应力及髓核间应力明显增大,其大小不随椎板减压节段范围的改变而明显改变。     

寰椎椎弓根螺钉联合经寰枢关节螺钉内固定稳定性的生物力学研究

【摘要】 目的：评估寰椎椎弓根螺钉联合经寰枢关节螺钉固定技术的力学稳定性。方法：选取成人颈椎新鲜标本6具,解剖剔除肌肉制备上颈椎完整模型（完整组）,用生物力学测试及计算机视觉分析软件测量在1.5Nm力矩下前屈后伸、左右侧弯和左右旋转时C1-C2的活动度（ROM）;破坏寰椎前弓和侧块制备不稳模型（失稳组）,再次测量相同力矩下各运动方向C1-C2的ROM活动度。随后暴露寰枢椎置钉点,根据先后顺序置入寰椎椎弓根螺钉+枢椎椎弓根螺钉固定（C1P+C2P组）、单纯经寰枢关节螺钉固定（TA组）、寰椎椎弓根螺钉+经寰枢关节螺钉固定（C1P+TA组）,依次分别测量相同力矩下各运动方向C1-C2的ROM,比较各组C1-C2 ROM的差异。结果：失稳组相较于完整组在六个方向上有更大的ROM,两组所有方向上的ROM均有显著性差异（P<0.05）;C1P+C2P组、C1P+TA组、TA组与失稳组比较,所有方向上的ROM均有显著性减少（P<0.05）,三组间比较,前屈、后伸、左旋转和右旋转方向上的ROM存在统计学差异（P<0.05）,C1P+TA组相似文献   

经椎板螺钉固定脊椎融合术治疗腰椎退变性不稳

目的 探讨经椎板螺钉（简称TLS）在腰椎退变性不稳脊椎融合术的固定价值。方法 6具较新鲜脊柱标本（L4～L5）分别在正常、不同程度髓核切除和TLS固定后进行稳定性实验,测量三维运动范围（ROM）。临床组应用TLS治疗腰椎退变性不稳脊椎融合41例。结果 与正常（对照组）相比,TLS单侧固定组的前屈、后伸、侧弯、旋转ROM分别减少2．92％、1．78％、5．77％和7．92％,双侧固定组分别减少15．59％、5．72％、15．18％和20．19％;“髓核半切＋TLS”组明显小于“核髓全切＋TLS”组和对照组。随访6～26个月,脊椎均融合,平均融合时间4．3个月,优20例,良18例,可3例。结论 TLS固定后脊柱各向稳定性增加,治疗腰椎退变性不稳脊椎融合固定简单、安全、较为可靠。     

Solis椎间融合器治疗Ⅱ型Hangman骨折的生物力学评价

目的:比较Solis椎间融合器、椎间植骨及椎间植骨+钢板内固定治疗Ⅱ型Hangman骨折的生物力学稳定性,为临床应用Solis椎间融合器治疗Hangman骨折提供理论依据.方法:6具成人新鲜冷冻颈椎标本,每具依次制作成以下5种状态组,即正常对照组(A组)、Ⅱ型Hangman骨折模型组(B组)、Solis椎间融合器置人组(C组)、单纯椎间植骨组(D组)、椎间植骨+钢板内固定组(E组).按以上顺序应用脊柱三维运动试验机和三维激光扫描仪测试每一状态下C2/3节段的三维运动范嗣(ROM).结果:与A组比较,B组前屈、后伸、旋转及侧弯ROM均显著增大(P<0.05);C组旋转ROM显著增大(P<0.05),其他方向无显著性差异(P>0.05);D组前屈、后伸及旋转ROM显著增大(P<0.05).侧弯方向无显著性差异:E组旋转ROM显著增大(P<0.05),其他方向无显著性差异(P>0.05).与B组比较,C组、E组均在前屈、后伸和侧弯方向及D组在后伸、侧弯方向ROM显著变小(P<0.05),C、D、E组旋转及D组前屈ROM与B组比较无显著性差异.C、D及E组相互比较,C组后伸ROM显著小于D组(P<0.05),其他方向与D组比较无显著性差异;C组前屈ROM显著大于E组(P<0.05),其他方向与E组比较无显著性差异;D组前屈、后伸及侧弯ROM均显著大于E组(P<0.05),旋转方向与E组比较无显著性差异.结论:在Ⅱ型Hangman骨折的治疗中,Soils椎间融合器有助于恢复前屈、后伸及侧弯方向上的稳定性,但在旋转方向上不能恢复稳定性,术后需辅以外固定,以确保融合;其稳定作用弱于钢板内固定,但优于单纯植骨.     

三种后路寰枢椎融合术的离体生物力学研究

目的 通过离体生物力学研究方法,比较3种后路寰枢椎融合技术的力学稳定性.方法 将8具新鲜尸体的颈椎标本(C1～4)置于1.5 Nm载荷下,测量C1、2关节的三维运动范围(ROM).每具标本依双侧经寰枢关节间隙螺钉结合Gallie内固定术、双侧经寰枢关节间隙螺钉结合寰椎椎板钩内固定术、双侧寰椎侧块螺钉结合枢椎椎弓根螺钉内固定术的顺序实施固定,每次固定后测量三维运动范围.结果 包含经寰枢关节间隙螺钉的内固定组在旋转和侧屈方向上具有最小的ROM角度,其中新型的双侧经寰枢关节间隙螺钉结合寰椎椎板钩内固定组在前屈后伸运动方向上也具有最小ROM角度.寰椎侧块螺钉结合枢椎椎弓根螺钉内固定组在旋转方向上ROM角度显著大于单独经寰枢关节螺钉内固定组,但在侧屈和前屈后伸方向上ROM角度近似于经寰枢关节间隙螺钉,差异无统计学意义.结论 双侧经寰枢关节间隙螺钉结合寰椎椎板钩内固定术具有最强的生物力学稳定性;双侧寰椎侧块螺钉结合枢椎椎弓根螺钉内固定术与双侧经寰枢关节间隙螺钉结合寰椎椎板钩内固定技术比较,具有相似的力学稳定性.     

聚乙烯醇水凝胶人工髓核置入对腰椎运动影响的生物力学研究

目的：研究髓核摘除后聚乙烯醇水凝胶人工髓核置入对腰椎活动度和椎间隙高度的影响.方法：对7具新鲜成人尸体L4/5正常椎间隙、髓核摘除后和置入人工髓核后在8.0Nm扭矩下的屈伸、侧弯和旋转的活动度（ROM）、中性区（NZ）和椎间隙高度变化进行测试、比较.结果：髓核摘除后,L4/5椎间屈伸、侧弯、旋转的ROM和NZ较正常组显著增加（P＜0.05或0.01）,在0和200N的负荷下椎间隙高度较相同情况下正常组分别下降1.2mm和1.7mm;置入人工髓核后,相对于正常椎间隙,L4/5椎间屈伸、侧弯、旋转的ROM和NZ无明显差异,较髓核摘除组明显下降（P＜0.05或0.01）,在0N和200N的负荷下椎间隙高度较相同情况下髓核摘除组分别增加1.6mm和2.0mm.结论：聚乙烯醇水凝胶人工髓核置入椎间盘切除后的椎间隙可有效恢复椎间隙高度,维持腰椎节段正常的三维运动功能稳定性.     

下颈椎经关节螺钉钉棒系统固定的生物力学研究

目的：比较下颈椎三柱损伤后单独经关节螺钉固定（TAS）、经关节钉棒系统同定（TRS）和侧块螺钉钉棒系统固定（LRS）的三维稳定性。方法：12具新鲜颈椎标本．制成C4／5、C5／6节段三柱损伤模型，分别进行单独经关节螺钉（TAS组）、经关节螺钉钉棒系统（TRS组）和侧块螺钉钉棒系统（LRS组）三种方法固定，在非限制性和非破坏性的实验条件下测试其前屈、后伸、左右侧弯和轴向旋转运动状态的稳定性。结果：TAS组和TRS组在各方向的运动范同（ROM）和中性区（NZ）的均数均显著小于完整标本组，差异有统计学意义（P〈0．05）；LRS组在前屈、后伸、侧弯运动中的ROM和NZ与完整标本组比较有显著降低，差异有统计学意义（P〈0．05）；LRS组在旋转运动中的ROM和NZ与完整标本组比较有不同程度的降低，但差异无统计学意义（P〉0．05）。TAS、TRS在各个方向稳定性明显优于LRS组（P〈0．05）。TRS在前屈运动中的ROM和NZ与TAS组比较有所减小，但无统计学意义（P〉0．05）；在后伸、侧弯和旋转运动中，TRS组稳定性明显优于TAS组，有统计学意义（P〉0．05）。结论：在下颈椎三柱损伤选择经关节固定技术时以钉棒形式同定稳定性更好。     

人工寰齿关节置换与Magerl经关节螺钉固定的生物力学比较

[目的]测试人工寰椎齿状突关节置换后寰枢椎的稳定性和功能,并与Magerl经关节螺钉固定进行比较.[方法]将12例新鲜的成人头颈部标本随机分为两组,第1组在齿状突切除术后使用人工寰齿关节置换;第2组在齿状突切除术后使用Magerl经关节螺钉固定.对两组的每一标本分别测定完整状态、人工关节置换术后或经关节螺钉固定后的运动范围和中性区.[结果]人工关节置换术后与完整状态相比前屈、后伸、左右侧屈的运动范围和中性区明显减小(P＜0.05),左右旋转的运动范围无显著差异(P＞0.05),中性区增大(P＜0.05).Maged经关节螺钉固定后与完整状态相比前屈、后伸、左右侧屈及左右旋转的运动范围和中性区均明显减小(P＜0.05).人工关节置换术后及Magerl经关节螺钉固定后两组在前屈、后伸及左右侧屈的ROM稳定指数和NZ稳定指数相比均无显著差异(P＞0.05).[结论]实验证实在齿状突切除后,进行自行设计的人工寰椎齿状突关节置换可取得与Magerl经关节螺钉固定相似的前屈、后伸及左右侧屈稳定性,重要的是与完整状态相比左右旋转的运动范围无显著差异,最大限度的保留了寰枢复合体重要的旋转功能,对以往齿状突切除、脊髓减压后需要使用寰枢椎融合的患者,提供了另一种术式的选择.     

应用经关节螺钉固定在寰枢关节不稳中的生物力学研究与临床应用

目的 探讨后路经关节螺钉固定(Magerl技术)加植骨融合治疗寰枢关节不稳定的生物力学特性及其临床价值.方法 生物力学研究:取新鲜冰冻尸体标本30具,随机分成5组:完整标本组、寰枢椎不稳实验模型组、寰枢椎后路椎弓根螺钉固定组、寰枢椎经关节螺钉固定组及寰枢椎经关节螺钉联合Brooks钢丝固定组,每组各6具.标本施加±1.5N·m纯力偶矩作为加载的最大力矩,模仿前屈、后伸,左、右侧弯,左、右轴向旋转6种生理性运动,测量各种生理性运动的活动范围(ROM)和中性区(NZ)值.应用SPSS 11.0软件进行统计分析,比较组间差异.临床研究:2000年2月至2005年1月应用寰枢椎经关节螺钉(Magerl技术)固定、C1.2棘突间植骨融合术治疗寰枢椎不稳患者23例,男16例,女7例;年龄17～62岁,平均38.6岁;先天性畸形致脱位3例,外伤性脱位20例.所有患者进行定期随访和影像学检查,评估颈椎稳定性和植骨融合率.结果 标本生物力学测试结果表明:屈伸稳定性、侧弯稳定性和轴向稳定性均为寰枢椎经关节螺钉联合Brooks钢丝固定组＞寰枢椎经关节螺钉固定组＞寰枢椎椎弓根螺钉固定组＞寰枢椎完整标本组＞寰枢椎不稳模型组,组间差异有统计学意义.临床研究表明:23例共放置经关节螺钉46枚;无一例发生椎动脉损伤、脊髓损伤或舌下神经麻痹等并发症.23例患者均获随访,随访时间4～36个月,平均15个月;随访中2例患者主诉旋转活动部分受限;影像学检查提示所有患者植骨全部融合.结论 单纯的Magerl螺钉固定失稳的寰枢关节具有足够坚固的生物力学性能,临床上结合棘突间植骨可达到满意的骨性融合.     

人工寰齿全关节置换后对寰枢关节稳定性和三维运动生物力学评价

目的 探讨人工寰齿关节置换后对寰枢关节稳定性和三维运动的生物力学性能.方法 选用12具新鲜尸体颈椎标本(包括枕骨基底部和C1～C4颈椎节段)置入1.53 Nm载荷下,依次轮流测试其完整状态、前路减压术后、Magerl螺钉固定后、人工寰齿关节置换后、疲劳实验后C1、C2节段标本的三维运动范围(ROM).结果 人工寰齿关节置换后,寰枢关节旋转运动范围和中性区接近正常状态,但屈伸和侧屈运动范围较前路减压术后和正常状态明显减少,差异有统计学意义(P＜0.05).在控制属伸和侧屈方向上,人工寰齿关节置换后同Magerl螺钉固定后表现出了最小的ROM(P＞0.05),但在控制寰枢关节旋转方向上,两者差异有统计学意义(P＜0.05).各进行2000次屈伸、侧屈和旋转疲劳实验后对人工寰齿关节置换后三维运动范围无明显影响,差异无统计学意义(P＞0.05).结论 自行研制的人工寰齿关节置换后既能重建寰枢关节良好的即刻稳定性又能保留其关节运动功能.     

下颈椎后路内固定器对失稳颈椎固定作用的生物力学评价

目的 评价下颈椎后路内固定器重建失稳颈椎稳定性的生物力学性能。方法 5具新鲜颈椎尸体标本制造脱位模型后依次用棘突钢丝、侧块螺钉、自制螺钉、椎弓根螺钉固定，用脊柱三维运动测量系统测算其运动范围。结果 棘突钢丝在屈伸和侧弯时的运动范围可恢复完整颈椎水平，但旋转时的运动范围比完整颈椎大。侧块螺钉和自制螺钉的运动范围均较完整颈椎小，且侧弯和旋转的运动范围明显小于棘突钢丝。椎弓根螺钉侧弯和旋转的运动范围最小。内固定相邻节段的运动范围虽有变化，但差异无显著性(P＞0．05)。结论 棘突钢丝可重建失稳颈椎的屈伸稳定性，但侧弯和旋转稳定性欠佳，侧块螺钉和自制螺钉优于棘突钢丝，椎弓根螺钉的稳定性最强。     

In vitro flexibility of the cervical spine after ventral uncoforaminotomy. Laboratory investigation

OBJECT: Degenerative spine disorders are, in the majority of cases, treated with ventral discectomy followed by fusion (also known as anterior cervical discectomy and fusion). Currently, nonfusion strategies are gaining broader acceptance. The introduction of cervical disc prosthetic devices was a natural consequence of this development. Jho proposed anterior uncoforaminotomy as an alternative motion-preserving procedure at the cervical spine. The clinical results in the literature are controversial, with one focus of disagreement being the impact of the procedure on stability. The aim of this study was to address the changes in spinal stability after uncoforaminotomy. METHODS: Six spinal motion segments derived from three fresh-frozen human cervical spine specimens (C2-7) were tested. The donors were two men whose ages at death were 59 and 80 years and one woman whose age was 80 years. Bone mineral density in C-3 ranged from 155 to 175 mg/cm3. The lower part of the segment was rigidly fixed in the spine tester, whereas the upper part was fixed in gimbals with integrated stepper motors. Pure moment loads of +/- 2.5 Nm were applied in flexion/extension, axial rotation, and lateral bending. For each specimen a load-deformation curve, the range of motion (ROM), and the neutral zone (NZ) for negative and positive directions of motion were calculated. Median, maximum, and minimum values were calculated for the six segments and normalized to the intact segment. Tests were done on the intact segment, after unilateral uncoforaminotomy, and after bilateral uncoforaminotomy. RESULTS: In lateral bending a strong increase in ROM and NZ was detectable after unilateral uncoforaminotomy on the right side. Overall, the ROM during flexion/extension was less influenced after uncoforaminotomy. The ROM and NZ during axial rotation to the left increased strongly after right unilateral uncoforaminotomy. Changes after bilateral uncoforaminotomy were marked during axial rotation to both sides. CONCLUSIONS: Following unilateral uncoforaminotomy, a significant alteration in mobility of the segment is found, especially during lateral bending and axial rotation. The resulting increase in mobility is less pronounced during flexion and least evident on extension. Further investigations of the natural course of disc degeneration and the impact on mobility after uncoforaminotomy are needed.     

单节段与双节段椎弓根螺钉固定胸腰椎单椎体骨折的生物力学比较

目的:比较单节段与双节段椎弓根螺钉固定术固定胸腰椎单椎体骨折的生物力学效果。方法:在16具新鲜小牛胸腰椎标本(T11-L3)的L1椎体上制作不完全爆裂骨折模型,分为两组,分别行单节段与双节段椎弓根螺钉固定,对固定后的标本施加扭矩为4Nm的疲劳载荷共2000次,加载频率为0.5Hz,经脊柱三维运动测量系统测量正常、损伤、固定和周期性加载后固定节段前屈/后伸、左/右侧弯和左/右旋转运动时固定节段的运动范围。结果:单节段固定组前屈、后伸、侧屈、旋转稳定指数(SPI)分别为0.78、0.80、0.92、0.83,双节段固定组SPI分别为0.88、0.89、0.95、0.85,在前屈方向单节段固定组明显小于双节段固定组(P<0.01);疲劳后,单节段固定组SPI在前屈、后伸、侧屈、旋转方向分别降低0.05、0.03、0.05、0.11,降低值均大于双节段固定组,且在旋转和侧屈方向有显著性差异(旋转:P<0.01;侧屈:P<0.05)。结论:两种术式均可重建脊柱骨折即刻稳定性,效果无明显差异。在旋转、侧屈方向,双节段椎弓根螺钉固定术抗疲劳载荷效果优于单节段固定术。     

前路腰椎椎间融合术即刻稳定性的生物力学研究

目的 评价应用聚醚醚酮(poly-ether-ether-ketone,PEEK)椎间融合器行前路腰椎椎间融合的即刻生物力学稳定性.方法 采用6具成人尸体腰椎标本,均来源于男性,X线榆查排除腰椎疾患和明显退行性改变,双能X线骨密度检查证实所有标本骨密度均处于正常范围.截取L4～S2节段腰椎,用自凝型聚甲基丙烯酸甲酯将标本两端固定在夹具内.沿腰椎轴线加载500N的预负荷后,分别在生物力学试验机上检测以下三种状态的前屈、后伸及侧屈各方向活动的即刻稳定性:完整腰椎标本,L5S1椎间盘切除、PEEK椎间融合器植入,辅以后路椎弓根螺钉系统固定.结果 L5S1椎间单纯椎间融合器植入后前屈、后伸、左侧屈方向的活动范围较完整腰椎标本分别减少76.9%、66.6%与81.1%;辅以后路惟弓根螺钉系统固定后,前屈、后伸、左侧屈方向的活动范围较完整腰椎标本分别减少93.9%、90%与86.6%.完整腰椎标本的空白对照组L4,5椎间前屈、后伸与左侧屈活动度分别为4.16°±0.33°、4.02°±0.30°、3.48°±0.34.;L5S1单纯椎间融合器组则分别为5.82°±0.36°、5.38°±0.30°、4.96°±0.29°;L5S1椎间融合器辅助椎弓根螺钉固定组则分别为4.82°±0.26°、5.76°±0.31°、3.98°±0.29°.L5S1椎间单纯椎间融合器植入及附加椎弓根螺钉崮定后,L4,5椎间相对活动度显著增加,各组间差异有统计学意义(P=0.000).结论 单纯应用PEEK椎间融合器的前路腰椎椎间融合术即刻稳定性优于完整腰椎标本.辅以后路椎弓根螺钉系统固定后融合节段稳定性得到显著增强.     

下腰椎不同融合方法的即刻与疲劳后稳定性

目的:观察下腰椎后路不同融合方法的即刻与疲劳后稳定性。方法:9具新鲜L1~S1尸体标本分别头尾端固定,在脊柱三维运动实验机上模拟人体行屈伸、左右侧弯及旋转活动,观察L4~L5节段运动范围(ROM),随后进行各种模拟手术并安装内固定,依次测定失稳腰椎、CD内固定(CD)、CD加椎体间植骨(CD-骨块)、CD加TFC(CD-TFC)状态下L4~L5的ROM值。随后在868Mini-MTS多轴生物力学实验机上对三种术式腰椎进行1500次疲劳加载,再观察L4~L5节段的ROM。结果:①失稳腰椎与正常腰椎比较在各运动方向上ROM均明显增加;②单纯CD内固定即刻稳定性好,但疲劳后呈不稳趋势,在屈伸及左右旋转方向明显失稳;③CD-骨块、CD-TFC稳定性好,疲劳后仍能维持良好的稳定性;④CD-骨块与CD-TFC疲劳组比较在屈伸及左右侧弯时ROM无明显差异,但CD-TFC在抗旋转方向优于CD-骨块组。结论:单纯后路短节段CD内固定和/或椎体间植骨融合均能提供良好的稳定性,但单纯后路短节段CD内固定抗疲劳性差,辅以椎间支撑(植骨或TFC)可有效提高抗疲劳稳定性。     

新型钛合金颈椎前路接骨板的三维稳定性试验

背景：目前,颈椎前路接骨板已经广泛应用于颈椎创伤、畸形、退行性变以及颈椎肿瘤的治疗。目的：应用新型钛合金研制颈椎前路多功能接骨板（multifunctional cervicalplate,MCP）,并且对其进行三维稳定性试验。方法：收集24具6个月左右宰杀的猪颈椎标本随机分为4组,每组6具标本。在连续的4种状态下,即完整状态、植骨状态、接骨板固定状态以及疲劳测试后状态,对颈椎C3-C7施加2.0Nm的纯力矩,测量标本前屈、后伸、左右侧屈、左右旋转的活动范围（rang of motion,ROM）和中性区（neutral zone,NZ）。结果：所有节段在6个方向的ROM上,MCP固定状态、MCP疲劳状态、C-mark接骨板（C-markplate,CMP）固定状态、CMP疲劳状态之间相比较,差异无统计学意义（P〉0.05）,但与完整状态、植骨状态相比较,差异均有显著统计学意义（P〈0.01）。在前屈、左右侧屈方向的ROM上,植骨状态与完整状态相比较,差异有显著统计学意义（P〈0.01）。在屈伸NZ上,MCP固定状态、MCP疲劳状态、CMP固定状态、CMP疲劳状态之间差异无统计学意义（P〉0.05）,但与完整状态、植骨状态相比较,差异均有显著统计学意义（P〈0.01）。在侧屈NZ上,除完整状态与其他状态之间有统计学意义外（P〈0.01）,其他状态之间没有差异（P〉0.05）。在旋转NZ上,所有状态之间均无统计学意义（P〉0.05）。结论：体外生物力学研究表明MCP能够给颈椎提供足够的三维稳定性,在进行扭转疲劳试验后仍然可以保持三维稳定性。     

Dynamics of an Intervertebral Disc Prosthesis in Human Cadaveric Spines

Low-back pain is a common, disabling medical condition, and one of the major causes is disc degeneration. Total disc replacements are intended to treat back pain by restoring disc height and re-establishing functional motion and stability at the index level. The objective of this study was to determine the effect on range of motion (ROM) and stiffness after implantation of the ProDisc®-L device in comparison to the intact state. Twelve L5–S1 lumbar spine segments were tested in flexion/extension, lateral bending, and axial rotation with axial compressive loads of 600 N and 1,200 N. Specimens were tested in the intact state and after implantation with the ProDisc®-L device. ROM was not significantly different in the implanted spines when compared to their intact state in flexion/extension and axial rotation but increased in lateral bending. Increased compressive load did not affect ROM in flexion/extension or axial rotation but did result in decreased ROM in lateral bending and increased stiffness in both intact and implanted spine segments. The ProDisc®-L successfully restored or maintained normal spine segment motion.     

Non-fusion instrumentation of the lumbar spine with a hinged pedicle screw rod system: an in vitro experiment

In advanced stages of degenerative disease of the lumbar spine instrumented spondylodesis is still the golden standard treatment. However, in recent years dynamic stabilisation devices are being implanted to treat the segmental instability due to iatrogenic decompression or segmental degeneration. The purpose of the present study was to investigate the stabilising effect of a classical pedicle screw/rod combination, with a moveable hinge joint connection between the screw and rod allowing one degree of freedom (cosmicMIA). Six human lumbar spines (L2–5) were loaded in a spine tester with pure moments of ±7.5 Nm in lateral bending, flexion/extension and axial rotation. The range of motion (ROM) and the neutral zone were determined for the following states: (1) intact, (2) monosegmental dynamic instrumentation (L4-5), (3) bisegmental dynamic instrumentation (L3–5), (4) bisegmental decompression (L3–5), (5) bisegmental dynamic instrumentation (L3–5) and (6) bisegmental rigid instrumentation (L3–5). Compared to the intact, with monosegmental instrumentation (2) the ROM of the treated segment was reduced to 47, 40 and 77% in lateral bending, flexion/extension and axial rotation, respectively. Bisegmental dynamic instrumentation (3) further reduced the ROM in L4-5 compared to monosegmental instrumentation to 25% (lateral bending), 28% (flexion/extension) and 57% (axial rotation). Bisegmental surgical decompression (4) caused an increase in ROM in both segments (L3–4 and L4–5) to approximately 125% and approximately 135% and 187–234% in lateral bending, flexion/extension and axial rotation, respectively. Compared to the intact state, bisegmental dynamic instrumentation after surgical decompression reduced the ROM of the two-bridged segments to 29–35% in lateral bending and 33–38% in flexion/extension. In axial rotation, the ROM was in the range of the intact specimen (87–117%). A rigid instrumentation (6) further reduced the ROM of the two-bridged segments to 20–30, 23–27 and 50–68% in lateral bending, flexion/extension and axial rotation, respectively. The results of the present study showed that compared to the intact specimen the investigated hinged dynamic stabilisation device reduced the ROM after bisegmental decompression in lateral bending and flexion/extension. Following bisegmental decompression and the thereby caused large rotational instability the device is capable of restoring the motion in axial rotation back to values in the range of the intact motion segments.     

Biomechanical comparison of transfacet screws to lateral mass screw-rod constructs in the lower cervical spine

Purpose

Transfacet screws have been used as an alternative posterior fixation in the cervical spine. There is lack of spinal stability of the transfacet screws either as stand-along constructs or combined with anterior plate. This study was designed to evaluate spinal stability of transfacet screws following posterior ligamentous injury and combined with anterior plate, respectively, and compare transfacet screws to lateral mass screw-rod constructs.

Methods

Flexibility tests were conducted on eight cadaveric specimens in an intact and injury, and instrumented with the transfacet screw fixation and lateral mass screw-rod construct at C5–C7 levels either after section of the posterior ligamentous complex or combined with an anterior plate and a mesh cage for C6 corpectomy reconstruction. A pure moment of ±2.0 Nm was applied to the specimen in flexion–extension, lateral bending, and axial rotation. Ranges of motion (ROM) were calculated for the C5–C7 segment.

Results

ROM with the transfacet screws was 22 % of intact in flexion–extension, 9 % in lateral bending and 11 % in axial rotation, while ROM with the lateral mass screw-rod construct was 9 % in flexion–extension, 8 % in lateral bending and 22 % in axial rotation. The only significant difference between two constructs was seen in flexion–extension (5.8 ± 4.2° vs. 2.4 ± 1.2°, P = 0.002). When combined with an anterior plate and mesh cage, the transfacet screw fixation reduced ROM to 3.0° in flexion–extension, 1.2° in lateral bending, and 1.1° in axial rotation, which was similar to the lateral mass screw-rod construct.

Conclusions

This study identified the transfacet screw fixation, as stand-alone posterior fixation, was equivalent to the lateral mass screw-rod constructs in axial rotation and lateral bending except in flexion–extension. When combined with an anterior plate, the transfacet screw fixation was similar to the lateral mass screw-rod construct in motion constraint. The results suggested the transfacet screw fixation a biomechanically effective way as supplementation of anterior fixation.