腰椎椎弓峡部裂单椎节经椎弓根钉棒固定体外生物力学研究

目的 通过生物力学实验评估单椎节经椎弓根钉棒固定方法(STSR)治疗不伴椎体滑脱的腰椎椎弓峡部裂的力学特性.方法 取人体下腰椎标本6具,在L4下关节突、L5上下关节突、S1上关节突分别贴应变片,在正常状态、L5双侧椎弓峡部裂状态、植入STSR内固定状态3种力学形态下分别测量应变片在力学加载时的应变量变化.结果 前屈时L5下关节突竖形应变量内固定状态与峡部裂状态比较减少27%;后伸时L4 下关节突竖形片、L5下关节突横形片、L5下关节突竖形片应变量内固定状态与峡部裂状态比较分别减少23%、21%和51%,以上差异均有统计学意义(P＜0.05).侧屈时L5下关节突竖形片内固定状态与峡部裂状态比较减少59%;旋转时L4下关节突竖形片应变量内固定状态与峡部裂比较减少57%,以上差异有统计学意义(P＜0.01).结论 STSR系统能恢复峡部裂造成的不稳定,与峡部裂状态比较在下腰椎前屈、后伸、侧屈、旋转运动时增加了相应关节突的稳定.     

腰椎髓核摘除后小关节应力分析

[目的]研究L4、5正常腰椎节段、髓核摘除术后腰椎节段小关节的应力大小和分布情况.[方法]利用有限元软件Ansys,建立L4、5正常节段和髓核摘除术后三维有限元模型.固定模型L5椎体下终板,在L4椎体上终板施加400 N的轴向压缩载荷,并在L4椎体上终板分别向模型施加前屈、后伸和右旋转力,力矩大小均为6 Nm.分析各个状态下腰椎小关节的应力分布情况.[结果]建立了L4、5腰椎节段正常、髓核摘除术后的三维有限元模型.小关节处理为三维接触模型,线性、面接触单元,无摩擦,由上下关节突关节面及韧带结构组成.正常模型两侧小关节在右旋转时均产生较大应力,而以左侧小关节产生应力更大.髓核摘除模型在前屈、后伸、旋转时小关节的应力均增加.[结论]在腰椎不同的运动状态下,两侧小关节面各个部位的接触情况是不同的,应力大小和分布也是变化的.髓核摘除后腰椎前柱的承载功能减弱,小关节等后柱结构分担载荷增大.     

内窥镜下后路腰椎椎体间融合附加单侧椎弓根螺钉固定的力学基础

[目的]通过生物力学试验评价内窥镜下后路腰椎椎体间融合(PLIF)附加单侧椎弓根螺钉固定的稳定性及力学合理性。[方法]建立PLIF术式相关的小牛腰椎模型,进行前屈、后伸、左右侧屈、扭转等的非破坏性测定,记录融合节段L4、5和邻近节段L3、4的应变、应力、腰椎的轴向刚度和扭转刚度等力学量并对比分析。[结果]PLIF附加单侧椎弓根螺钉固定组融合节段上的应变、应力在前屈、后伸、侧屈等工况下较正常组有所减少但差异无统计学意义(P>0.05),而与PLIF附加双侧椎弓根螺钉固定组间差异有非常显著性意义(P<0.01)。在500 N载荷作用下,PLIF附加单侧椎弓根螺钉固定组脊柱位移为(2.56±0.34)mm,轴向刚度较正常组增加了5%,但差异无统计学意义(P>0.05);而与PLIF附加双侧椎弓根螺钉固定组间差异有统计学意义(P<0.05)。PLIF附加单侧椎弓根螺钉固定后扭转刚度较正常组差异无显著性(P>0.05),但明显低于PLIF附加双侧椎弓根螺钉固定组(P<0.05)。同时,PLIF附加单侧椎弓根螺钉固定后,邻近节段L3、4小关节上的应变、应力及L3、4椎间盘上的应力在各种不同工况下与正常组间差异无统计学意义(P>0.05),而在前屈时与PLIF附加双侧椎弓根螺钉固定组间差异有统计学意义(P<0.05)。[结论]PLIF附加单侧椎弓根螺钉固定可以弥补由于后方骨性和韧带结构部分破坏所造成的医源性不稳,增强腰椎的初始稳定性;在重建脊柱稳定性的同时,并没有增加邻近节段退行性疾病发生的危险。     

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。     

腰椎间盘突出症后路髓核摘除术后远期并发关节突骨折

[目的]探讨腰椎间盘突出症后路髓核摘除术后远期并发关节突骨折的发病机理、临床特征及治疗措施。[方法]本组6例，原腰椎间盘突出症后路髓核摘除术式：半椎板切除5例，扩大开窗术1例。骨折的关节突均为半椎板切除或椎板开窗椎的下关节突。[结果]1例进行了再次髓核摘除术、经椎弓根内固定加植骨术，其余5例保守治疗后症状缓解或消失。[结论]作为腰椎间盘突出症后路髓核摘除术后复发的原因之一，关节突骨折值得重视。早期诊断，适当处理，预后良好。     

不同入路经皮内窥镜下关节成形术对椎间盘生物力学影响的三维有限元分析

目的:通过三维有限元法分析经皮内窥镜下L4下关节突成形术与L5上关节突成形术对椎间盘生物力学的影响。方法:选取1例健康青年男性志愿者,对其进行薄层螺旋CT扫描,建立正常的L3～L5三维有限元模型,将上述有限元模型与经典文献数据进行验证。验证后,模拟腰椎经皮内窥镜技术分别于侧后方入路对L5上关节突与后方入路对L4下关节突做直径7.5mm的圆柱状骨切除以模拟椎间孔成形,从而获得正常模型、L5上关节突成形模型(A模型)和L4下关节突成形模型(B模型)3种模型。在L3椎体上表面向终板施加负荷为400N的垂直于水平面压力模拟正常人腰椎承载重力,在前屈、后伸、左右侧弯、左右旋转的方向上分别施加7.5N·m的纯扭矩,比较3种模型在前屈、后伸、左右侧曲、左右旋转状况下L3/4、L4/5椎间盘应力变化情况。结果:A模型前屈、后伸、左侧屈、右侧屈、左旋、右旋状态下L4/5椎间盘的最大应力分别为0.390MPa、0.520MPa、0.450MPa、0.430MPa、0.510MPa和0.498 MPa;B模型前屈、后伸、左侧屈、右侧屈、左旋、右旋状态下L4/5椎间盘的最大应力分别为0.375MPa、0.490MPa、0.440MPa、0.420MPa、0.482MPa和0.478MPa。A模型前屈、后伸、左侧屈、右侧屈、左旋、右旋状态下L3/4椎间盘的最大应力分别为0.369MPa、0.480MPa、0.442MPa、0.432MPa、0.468MPa和0.452MPa;B模型前屈、后伸、左侧屈、右侧屈、左旋、右旋状态下L3/4椎间盘的最大应力分别为0.368MPa、0.478MPa、0.436MPa、0.430MPa、0.465MPa和0.444MPa。结论:腰椎经皮内窥镜技术下,侧后入路L5上关节突成形较后方入路L4下关节突成形对L4/5椎间盘在后伸、旋转状态下的生物力学影响较大。两者对邻近节段L3/4椎间盘的应力变化的影响较小。     

节段开窗髓核摘除对腰椎稳定性的影响

目的 本研究观察了腰椎椎板节段开窗髓核摘除对腰椎稳定性的影响。方法 ７具新鲜腰骶椎标本头尾端固定,模拟人体行屈曲,侧弯和旋转活动,随后顺序进行Ｌ３－Ｓ１椎板节段开窗及Ｌ４－５,Ｌ５,Ｓ１髓核摘除,对比观察术前和多节段椎板双侧开窗及髓核摘除术后腰椎各节段在三维空间的位移变化,结果 单纯多节段开窗后屈江活动时Ｌ４,５前后水平和轴向位移分别增加１８％和１６％,Ｌ５Ｓ１则分别增加１９％和４５％,椎板开窗加     

单侧小关节分级切除对腰椎稳定性影响的三维有限元分析

目的研究单侧小关节分级切除对腰椎稳定性的影响。方法采用三维有限元法建立腰椎活动节段（L4～5）的数学力学模型。结果a）在前屈和后伸状态下,各实验切除组与正常对照组无显著性差异（P〉0．05）;b）在左／右侧弯和左／右轴向旋转状态下,小关节切除1／2以上的各组均与正常组有显著性差异（P〈0．05或P〈0．01）。结论a）单侧小关节分级切除对腰椎节段的前屈、后伸稳定性无显著性影响;b）当腰椎小关节切除范围超过1／2,对腰椎节段侧弯运动有显著性影响,尤其以向对侧侧屈为甚;c）当一侧小关节切除超过1／2后,由于失去了小关节和关节囊的限制,导致腰椎活动节段轴向旋转范围增加显著。     

经Coflex固定下腰椎不同节段后的椎间盘

目的 ：模拟临床术式,经Coflex分别固定下腰椎L4,5、L5S1节段,分析其手术节段及邻近节段椎间盘生物力学的差异性。方法：建立下腰椎及Coflex应用于下腰椎的3组有限元模型（完整下腰椎、Coflex固定腰椎L4,5及L5S1节段）。根据脊柱三柱加载理论,模拟下腰椎直立、前屈和后伸3种生理状态下,比较分析纤维环不同区域的应力大小、椎间隙背侧高度变化及髓核内压水平。结果：在直立和后伸工况下,Coflex分别植入L4,5、L5S1节段,均能减少其手术节段纤维环后区应力,限制椎间隙高度变化,并且降低髓核的应力水平。在后伸工况下,Coflex植入L4,5节段可降低L5S1节段的椎间盘应力水平,但Coflex植入L5S1节段不改变L4,5节段椎间盘应力大小。结论：Coflex固定L4,5、L5S1节段均能减少本手术节段椎间盘负载。另外,Coflex固定L4,5节段,起到降低L5S1节段椎间盘负载的生物力学效果。     

猪腰椎间盘髓核摘除术后循环载荷对腰椎稳定性的影响

[目的]评价轴向循环载荷对腰椎间盘髓核摘除术后腰椎稳定性的影响.[方法]从6具新鲜猪腰椎标本上截取18个脊柱功能单位(FSU),行单侧椎板开窗髓核摘除术,根据施加轴向循环载荷峰值的不同随机分为A、B、C三组(300～500 N、300～2 000 N、300～3 500 N),每组6个标本,观察其轴向循环载荷前后椎间盘高度的变化,以及在轴向压缩、前屈后伸和左右侧弯等运动工况下,椎间盘的应变、位移和轴向压缩刚度变化.[结果]循环载荷前后,A组椎间盘高度、刚度、位移变化无显著性差异(P＞0.05),应变增大有显著性差异(P＜0.05);B、C组椎间盘高度和刚度的降低、应变和位移的增大均有显著性差异(P＜0.01).循环载荷后三组间比较,椎间盘高度、应变、位移和刚度的变化幅度均随轴向循环载荷峰值的增大而变大(P＜0.05).[结论]腰椎间盘髓核摘除术后轴向循环载荷使腰椎稳定性下降,并且随着峰值载荷的增大,稳定性逐渐降低.提示对于临床病例,腰椎间盘髓核摘除术后不宜过早下床负重活动,术后早期较小的椎间盘载荷有利于腰椎稳定性的修复.     

Detailed pathological changes of human lumbar facet joints L1–L5 in elderly individuals

Facet joints play an important role in intervertebral load transmission and are crucial for rotational kinematics. Clinically, the role of facet joints as a possible source of low back pain is seen as controversial and at present is not sufficiently investigated. In this study, human lumbar facet (zygapopyhysial) joints from donors with advanced age were analyzed macroscopically, for degenerative changes. The aim was to determine the extent and morphology of degenerative changes in these joints. Lumbar facet joints (L1–L5) of 32 donors were studied (mean age 80.1±11.2 years). Joint capsules were carefully removed and joint surfaces (5 zones) examined using magnifying glasses and probes. In the result, the majority of facet joints showed cartilage defects of varying extent. Defects were located mostly at the margins of the articular surface, the central zone being relatively well preserved. Defect localization was different between superior (most cartilage defects in superior zone) and inferior (most defects inferiorly) facets. Further, defects were more severe caudal (level of L5) and in older persons. Osteophytes were present in up to 30%, located mostly at the latero-dorsal enthesis of the joint capsule on the superior facet. In conclusion, most margins of the articular facets are subject to degenerative changes in the lumbar spine of elderly persons, the topographical pattern being different in superior and inferior facets. This observation can be explained by the segmental motion patterns during extension/flexion movements of the facets. Sometimes, due to the marginal extension, it is obvious that not all changes can be assessed by CT or MRI.     

Functional MRI of the spine: different patterns of positions of the forward flexed lumbar spine in healthy subjects

Since the introduction of the technique of vertical open-configuration systems, efforts have been made to obtain functional lumbar spinal magnetic resonance (MR) images. The purpose of this study was to determine the relation between facet joint orientation and flexion patterns in the lower lumbar spine. Thirty-four normal subjects (18 women, 16 men) were examined in a vertical open 0.5-T MR scanner with T1-weighted gradient echo (GE) sequences. Flexion angles were digitally measured in the sagittal plane and facet joint orientation in the axial plane. The population showed three different functional flexion patterns: 17.6% (n=6) had kyphotic angles in all three lower lumbar levels during forward flexion (type 1), 50% (n= 17) had a lordotic angle at L5/S1 but kyphotic angles at L4/L5 and L3/L4 (type 2), and 32.4% (n=11) showed lordotic angles at L5/S1 and L4/L5 but a kyphotic angle at L3/L4 (type 3). There were statistically significant differences between flexion patterns and mean facet joint orientation: at 4/15 33.3 degrees for type 1, 33.5 degrees for type 2 and 46.2 degrees for type 3; at L5/S1 27.2 degrees for type 1, 46.4 degrees for type 2 and 48.1 degrees for type 3. There were no significant differences between the three groups at L3/L4. The three different flexion patterns in normal subjects and their relation to facet joint orientation have not been described previously. Knowledge of these patterns may lead to a better understanding of physiological spinal movement as a base for future investigations in low back pain patients.     

椎间盘摘除术对腰椎稳定性的影响

本实验研究应用Ｅｌｉｔｅ三维立体摄像运动分析系统观察一个节段和多个节段椎间盘摘除对整个腰椎稳定性的影响。结果表明，单纯Ｌ４～５椎间盘摘除术后于屈曲３０°时，Ｌ４～５水平位移（Ｔｚ）及旋转位移（Ｒｘ）有明显增加。Ｌ４～５及Ｌ５～Ｓ１椎间盘同时摘除术后于屈曲１０°时，不但Ｌ４～５及Ｌ５～Ｓ１节段Ｔｚ和Ｒｘ显著增加，同时亦有相邻的Ｌ３～４节段活动显著增加。实验结果提示，椎间盘摘除术后，特别是多个椎间盘摘除术后，有导致腰椎在生理活动范围内出现手术节段及相邻节段不稳的倾向。     

The biomechanical effects of graded upper articular process arthroplasty on lumbar spine: A finite element study

BackgroundSuperior articular process arthroplasty is important for intervertebral foramen microscopy but may lead to spinal instability. Currently, there has been no relevant study in relation to the biomechanical analysis of superior articular process arthroplasty. Hence, this study is intended to verify biomechanical effects after unilateral S1 superior articular process arthroplasty.MethodsEight finite element (FE) models of lumbosacral vertebrae (L4-S) were constructed, and the superior articular process formation was simulated with the help of Geomagic studio. Then, the models were imported into Nastran software after optimization. Normal load and appropriate torque were applied to simulate forward flexion, back extension, lateral flexion and lateral rotation. In the end, changes of lumbar range of motion (ROM) and structural stress were compared with those of normal model.ResultsCompared with the normal model, formed from ventral to dorsal (Longitudinal), the larger motion of lumbar spine and the greater larger stress of articular process showed statistical significance (P < 0.05) in most of directions when the forming range was greater than 3/5. Formed from the apex to the base (transverse), the larger motion of lumbar spine and the greater stress of articular process showed statistical significance (P < 0.05) in most of directions when the forming range was great than 1/5.ConclusionWhen conducting unilateral S1 articular process arthroplasty from ventral to dorsal, the forming range is recommended to be less than 3/5 of the superior articular process. Notably, it is not advisable to form from the apex to the base.     

Kinematics of the whole lumbar spine. Effect of discectomy

The biomechanical effects of discectomy on the motion behavior of whole lumbar spine are investigated using a Selspot II system. Fresh human ligamentous specimens were potted at the sacrum and clinically relevant loads (flexion/extension, right/left lateral bending, and right/left axial torsion moments) applied through a loading frame attached rigidly to the topmost vertebra of the specimen. The resulting three-dimensional motions of each vertebra for the intact specimen were recorded. The specimen was injured sequentially on the right side of the L4-5 level: partial laminectomy, partial facetectomy, subtotal discectomy, and total discectomy. The motion behavior of the specimen after each injury was recorded. The results of the injured tests were normalized with respect to the corresponding intact results. The normalized data for eight specimens were pooled for statistical analysis. Subtotal discectomy induced significantly less motion at the injury site than total discectomy, in all loading modes. At L3-4, the motion segment above the injury level, anteroposterior translation in flexion and lateral translation in left lateral bending show significant increases irrespective of the amount of nucleus excised. The clinical relevance of these findings are discussed.     

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。     

Internal and external responses of anterior lumbar/lumbosacral fusion: nonlinear finite element analysis

STUDY DESIGN: Determination of external and internal responses of the human lumbosacral spine using a validated 3-dimensional finite element model. OBJECTIVE: The objective of the present study was to evaluate the range of motion, disc stress, and facet joint pressure owing to anterior fusion at L4-L5 or L5-S1 level and compare with the intact spine. SUMMARY OF BACKGROUND DATA: A significant majority of finite element models of anterior lumbar interbody fusion are primarily focused on upper and middle levels, whereas lower spinal levels are most commonly treated with surgery. METHODS: A 3-dimensional L4-S1 finite element model, validated in the entire nonlinear range of the moment-rotation response, was used to determine ranges of motion, disc stress, and facet joint contact pressure under normal and 2 surgical conditions with bone graft and porous tantalum. Biomechanical responses were compared under flexion and extension loading between the 2 fusions and fusion masses and at the fused and intact segments. RESULTS: Moment-rotation responses were nonlinear under all conditions. The range of motion at the caudal level was greater than the range of motion at the rostral level in the intact spine. The range of motion of the L4-S1 spine decreased more with the caudal than rostral fusion and more with the tantulum than bone under both loading modes. Facet joint pressures increased more with the rostral than caudal fusion. Stresses in the adjacent disc were greater with the caudal than rostral fusion under both modes of loading. CONCLUSIONS: At the fused level, the caudal fusion imparted additional rigidity under flexion to the lumbosacral joint. Both fusion masses added flexibility to the adjacent segment. Under both fusion masses, increased facet joint pressure in the lumbosacral joint indicates the susceptibility of this transitional joint to long-term biomechanics-induced consequences. Increased facet joint pressures with the rostral fusion indicate that the posterior complex responds with increased load sharing, and may predispose the spine to facet-related arthropathy. Increased stresses in the adjacent disc with the caudal fusion under both modes of loading imply the potential to disc-related changes owing to long-term physiologic loading.     

脊柱旋转手法治疗腰椎间盘突出症的实验研究

采用模拟手法对３具新鲜尸体的脊柱标本，进行了Ｌ４．５、Ｌ５Ｓ１椎间盘后外缘应力变化的测定，和脊柱不同位置变化下腰椎小关节突相互关系改变的观察。结果发现前屈侧弯旋转法对腰椎小关节突的活动幅度最大，直立旋转法次之，向左侧旋转时小关节突作切面的旋转滑动，右侧小关节间隙增大；向右侧旋转时反之。做前屈侧弯旋转法时，当脊柱向左侧旋转时，椎间盘左后外侧压力增高，同时右后外侧压力减低；向右旋时则反之。而当旋转动作结束复原时，出现负压的一侧均出现一个微小的正压，这种正负压力多次反复的变化，可以使突出的髓核变位或变形，从而使受压的神经根减张。