The effect of anterior longitudinal ligament resection on lordosis correction during minimally invasive lateral lumbar interbody fusion: Biomechanical and radiographic feasibility of an integrated spacer/plate interbody reconstruction device

BackgroundLateral lumbar interbody fusion is powerful for correcting degenerative conditions, yet sagittal correction remains limited by anterior longitudinal ligament tethering. Although lordosis has been restored via ligament release, biomechanical consequences remain unknown. Investigators examined radiographic and biomechanical of ligament release for restoration of lumbar lordosis.MethodsSix fresh-frozen human cadaveric spines (L3–S1) were tested: (Miller et al., 1988) intact; (Battie et al., 1995) 8 mm spacer with intact anterior longitudinal ligament; (Cho et al., 2013) 8 mm spacer without intact ligament following ligament resection; (Galbusera et al., 2013) 13 mm lateral lumbar interbody fusion; (Goldstein et al., 2001) integrated 13 mm spacer. Focal lordosis and range of motion were assessed by applying pure moments in flexion-extension, lateral bending, and axial rotation.FindingsCadaveric radiographs showed significant improvement in lordosis correction following ligament resection (P < 0.05). The 8 mm spacer with ligament construct provided greatest stability relative to intact (P > 0.05) but did little to restore lordosis. Ligament release significantly destabilized the spine relative to intact in all modes and 8 mm with ligament in lateral bending and axial rotation (P < 0.05). Integrated lateral lumbar interbody fusion following ligament resection did not significantly differ from intact or from 8 mm with ligament in all testing modes (P > 0.05).InterpretationLordosis corrected by lateral lumbar interbody fusion can be improved by anterior longitudinal ligament resection, but significant construct instability and potential implant migration/dislodgment may result. This study shows that an added integrated lateral fixation system can significantly improve construct stability. Long-term multicenter studies are needed.     

Effect of cage design,supplemental posterior instrumentation and approach on primary stability of a lumbar interbody fusion – A biomechanical in vitro study

BackgroundThere are various techniques and approaches for lumbar interbody fusion differing in access, cage type and type of supplemental posterior instrumentation. While a transforaminal access usually includes a hemifacetectomy, the facet joint can be preserved with a more lateral extraforaminal access. The supplemental posterior instrumentation required for both fusion techniques is still debated. The purpose of the present study was to compare primary stability of the two accesses for two different cage types with none, unilateral and bilateral supplemental posterior instrumentation.MethodsSix monosegmental lumbar functional spinal units (FSUs) were included in each of the two groups, and subjected to a flexibility test. As cages, a newly designed cage was compared to a standard cage in the following states: (a) native, (b) stand-alone cage, (c) bilateral internal fixator, (d) unilateral internal fixator, (e) unilateral facetectomy + bilateral internal fixator, (f) unilateral facetectomy + unilateral internal fixator and (g) unilateral facetectomy with stand-alone cage. For comparison the range of motion was normalized to the native state and the effects of the facetectomy, cage type, and supplemental instrumentation was compared.FindingsWithin the subject comparison showed a significantly higher flexibility for the unilateral facetectomy in all motion directions (p < 0.001).In between subject comparison showed a significant effect of cage type on flexibility in flexion/extension (p = 0.002) and lateral bending (p = 0.028) but not in axial rotation (p = 0.322). The type of supplemental posterior fixation had a significant effect on the flexibility in all motion directions (stand-alone > unilateral fixator > bilateral fixator).InterpretationCage design and approach type are affecting the primary stability of lumbar interbody fusion procedures while the type of posterior instrumentation is the most influencing factor.     

Guidelines for cortical screw versus pedicle screw selection from a fatigued decompressive lumbar laminectomy model show similar stability and less bone mineral density dependency

BackgroundTraditional pedicle screws are the gold standard for lumbar spine fixation; however, cortical screws along the midline cortical bone trajectory may be advantageous when lumbar decompression is required. While biomechanic investigation of both techniques exists, cortical screw performance in a multi-level lumbar laminectomy and fusion model is unknown. Furthermore, longer-term viability of cortical screws following cyclic fatigue has not been investigated.MethodsFourteen human specimens (L1–S1) were divided into cortical and pedicle screw treatment groups. Motion was captured for the following conditions: intact, bilateral posterior fixation (L3–L5), fixation with laminectomy at L3–L5, fixation with laminectomy and transforaminal lumbar interbody fusion at L3–L5 both prior to, and following, simulated in vivo fatigue. Following fatigue, screw pullout force was collected and “effective shear stress” [pullout force/screw surface area] (N/mm²) was calculated; comparisons and correlations were performed.FindingsIn flexion-extension and lateral bending, all operative constructs significantly reduced motion compared to intact (P < 0.05), regardless of pedicle or cortical screws; only posterior fixation with and without laminectomy significantly reduced motion in axial rotation (P < 0.05). Pedicle screws significantly increased average pullout strength (944.2 N vs. 690.2 N, P < 0.05), but not the “effective shear stress” (1.01 N/mm² vs. 1.1 N/mm², P > 0.05).InterpretationIn a posterior laminectomy and fusion model, cortical screws provided equivalent stability to pedicle screw fixation, yet had significantly lower screw pullout force. No differences in “effective shear stress” warrant further investigation of the effect of screw length/diameter in the aforementioned screw trajectories.     

单侧腰椎弓根螺钉及经椎板关节突螺钉固定与双侧固定的比较

背景：经椎板关节突关节螺钉固定、椎问植骨融合治疗脊柱疾患是一种独特的固定方法,可用于退变性腰椎的融合。目的：比较采用微创经腰椎间孔椎体融合联合单侧椎弓根螺钉及经椎板关节突螺钉固定与常规开放后路腰椎体间融合术联合双侧椎弓根螺钉固定治疗下腰痛疾病的临床效果。方法：纳入2010年6月至2012年6月于武警广东总队医院就诊的腰椎间盘突出伴腰椎轻度不稳患者49例,均采用后路减压椎间融合器植骨内固定治疗。其中24例采用微创经椎间孔椎体融合术联合单侧椎弓根螺钉及经椎板关节突螺钉固定,25例采用常规开放后路腰椎体间融合术联合双侧椎弓根螺钉固定,比较两种固定方法的临床疗效。结果与结论：两种固定方法术后椎体融合率、日本矫形外科协会评分及疼痛目测类比评分改善率差异均无显著性意义（P〉0．05）。可见对无严重不稳的单节段退变性腰椎疾病患者,两种治疗方法的效果相当,均能有效提高椎间融合率,使小关节稳定,解除临床症状,门诊随访满意。但采用微创经椎间孔椎体融合术联合单侧椎弓根螺钉及经椎板关节突螺钉固定的患者手术切口长度、手术时间、术中出血量、术后切口引流液量明显减少（P〈0．05）,说明该方法具有创伤小、操作简单的优势。     

三种单纯腰椎椎间融合并双侧椎弓根螺钉内固定后即刻稳定性的比较

背景:椎间融合术按照手术入路主要有前路椎间融合术、后路椎间融合术和椎间孔入路椎问融合术.3种融合术术中切除的结构不同,融合器置入的部位不同,其腰椎即刻稳定性也存在差异.目的:比较前路椎间融合术、后路椎间融合术、椎间孔入路椎间融合术加用双侧椎弓根螺钉内固定后腰椎即刻稳定性的差异.设计:对比观察.材料:腰椎标本来自新鲜小牛15具.方法:模拟临床手术建立前路椎间融合术、后路椎间融合术、椎间孔入路椎间融合术3种椎间融合术模型,先将所有标本作为正常对照组进行测试,然后将标本随机分为3组,每组5个标本,制成单纯椎间融合组,分别采用3种椎间融合术测试后,在此基础上再附加双侧椎弓根螺钉内固定进行测试.主要观察指标:脊柱三维运动测试机上测试3种模型加用双侧椎弓根螺钉固定前后腰椎生物力学特性的变化.结果:行3种单纯椎间融合后,腰椎的稳定性能明显下降,附加了双侧椎弓根螺钉固定后,腰椎的各项稳定性指标均增强,包括扭转力学指标也得到了很大增强,有效增加了腰椎的刚度.椎间孔入路椎间融合术各项稳定性指标都明显优于其他两种方法,说明椎间孔入路椎间融合术的即刻稳定性能在3者中最有优势.后路椎间融合术的刚度明显强于前路椎间融合术,应变和应力也较前路椎间融合术有优势,但是其扭转稳定性却不如前路椎间融合术.结论:行单纯椎间融合术后,腰椎的稳定性较正常对照组均宵明显下降,在加用双侧椎弓根螺钉内固定后能有效地提高其稳定性能.在3种椎间融合术中,椎间孔入路椎间融合术的腰椎即刻稳定性能最优.     

腰椎间融合后路非对称与对称固定螺钉应力的有限元比较

背景：经椎间孔腰椎间融合非对称固定的生物力学稳定性研究,发现固定效果与双侧椎弓根螺钉接近,可满足临床应用所需生物力学要求。经关节突椎弓根螺钉参与经椎间孔腰椎间融合非对称固定的螺钉力学安全性又会怎样呢？目的：建立L4＋s功能节段左侧经椎间孔腰椎间融合后,分别予以同侧椎弓根螺钉＋对侧经关节突椎弓根螺钉、同侧椎弓根螺钉＋对侧经椎板关节突螺钉及双侧椎弓根螺钉固定的三维有限元模型,施加相同的载荷,分析不同运动状态下螺钉应力分布特点,比较3种螺钉应力状况。方法：对一成人正常L4—5椎节段标本、椎间融合器、椎弓根螺钉和皮质骨螺钉进行64排螺旋CT扫描,通过Mimicsll．1建立左侧经椎间孔腰椎间融合后3种内固定组合（同侧椎弓根螺钉＋对侧经椎板关节突螺钉、同侧椎弓根螺钉＋对侧经关节突椎弓根螺钉及双侧椎弓根螺钉固定）的几何模型,利用Simpleware3．1软件分别建立三维有限元模型,模拟500N惦Nm载荷下前屈、后伸、左＼右侧弯、左＼右侧旋等6种运动状态,用Abaqus6．8软件进行螺钉应力变化和分布特点分析。结果与结论：由于经椎间孔腰椎间融合入路切除了左侧关节突,造成内植物应力分布不对称,对弹性模量大的内固定器械一椎弓根螺钉应力影响最大,尤其是在左旋运动时。在不对称组合内固定中,由于关节突关节螺钉的使用,使对侧椎弓根螺钉应力相应增加,以左旋运动时尤为明显,但关节突关节螺钉断裂的危险性增高不明显。提示为降低螺钉断裂的风险,经椎间孔腰椎间融合后路3种组合内固定均应严格限制旋转运动,尤其是关节突切除侧的旋转运动。     

双侧钉棒及同侧单钉棒置入内固定的生物力学比较

背景：腰椎失稳、腰椎滑脱等腰椎退行性疾病常常需要实施腰椎融合,其目标是稳定脊柱,但究竟采取何种内固定方式仍存在争论。目的：比较单侧与双侧经椎间孔减压椎体间融合治疗腰椎退行性病变的生物力学差异。方法：人新鲜尸体腰椎标本6具,L4～5模拟微创经椎间孔减压椎体间融合,根据不同的内固定组合方式分为2组,即双侧钉棒组及同侧单钉棒组。在生物力学试验机上测量各种固定方式不同工况下的运动范围（ROM值）,并进行比较。结果与结论：以完整的腰椎运动单元为参照,两固定组的ROM值均低于对照组（P〈0.05）。其中双侧钉棒组在各工况下ROM值均显著低于同侧单钉棒组（P〈0.05）。提示在生物力学实验中,单侧椎弓根螺钉固定椎间融合生物力学性能优良,刚度适中,腰椎可获得可靠的稳定性。但与双侧钉棒固定比较,单钉棒方式仍然存在差距。     

Biomechanical evaluation of anterior lumbar interbody fusion with various fixation options: Finite element analysis of static and vibration conditions

BackgroundAnterior lumbar interbody fusion combined with supplementary fixation has been widely used to treat lumbar diseases. However, few studies have investigated the influence of fixation options on facet joint force and cage subsidence. The aim of this study was to explore the biomechanical performance of anterior lumbar interbody fusion with various fixation options under both static and vertical vibration loading conditions.MethodsA previously validated finite element model of the intact L1–5 lumbar spine was employed to compare five conditions: (1) Intact; (2) Fusion alone; (3) Fusion combined with anterior lumbar plate; (4) Fusion combined with Coflex-F fixation; (5) Fusion combined with bilateral pedicle screw fixation. The models were analyzed under static and vertical vibration loading conditions respectively.FindingsBilateral pedicle screws provided highest stability at surgical level. Applying supplementary fixation diminished the dynamic responses of lumbar spine. Compared with anterior lumbar plate and Coflex-F device, bilateral pedicle screws decreased the stress responses of the endplates and cage under both static and vibration conditions, while increased the facet joint force at adjacent levels. As for comparison between Coflex-F device and anterior lumbar plate, results showed a similarity in biomechanical performance under static loading, and a slightly higher dynamic response of the latter under vertical vibration.InterpretationThe biomechanical performance of lumbar spine was significantly influenced by the variation of fixations under both static and vibration conditions. Bilateral pedicle screws showed advantages in stabilizing surgical segment and relieving cage subsidence, but may increase the facet joint force at adjacent levels.     

Comparative analysis of posterior fusion constructs as treatments for middle and posterior column injuries: An in vitro biomechanical investigation

BackgroundTitanium pedicle screw–rod instrumentation is considered a standard treatment for spinal instability; however, the advantages of cobalt-chromium over titanium is generating interest in orthopedic practice. The aim of this study was to compare titanium versus cobalt–chromium rods in posterior fusion through in vitro biomechanical testing.MethodsPosterior and middle column injuries were simulated at L3–L5 in six cadaveric L1-S1 human spines and different pedicle screw constructs were implanted. Specimens were subjected to flexibility tests and range of motion, intradiscal pressure and axial rotation energy loss were statistically compared among five conditions: intact, titanium rods (with and without transverse connectors) and cobalt–chromium rods (with and without transverse connectors).FindingsAll fusion constructs significantly (P < 0.01) decreased range of motion in flexion–extension and lateral bending with respect to intact, but no significant differences (P > 0.05) were observed in axial rotation among all conditions. Intradiscal pressure significantly increased (P ≤ 0.01) after fusion, except for the cobalt–chrome conditions in extension (P ≥ 0.06), and no significant differences (P > 0.99) were found among fixation constructs. In terms of energy loss, differences became significant P ≤ 0.05 between the cobalt ? chrome with transverse connector condition with respect to the cobalt–chrome and titanium conditions.InterpretationThere is not enough evidence to support that the cobalt–chrome rods performed biomechanically different than the titanium rods. The inclusion of the transverse connector only increased stability for the cobalt–chromium construct in axial rotation.     

Comparison of effects of four interbody fusion approaches on the fused and adjacent segments under vibration

BackgroundWhich lumbar fusion approaches having fewer impacts on the lumbar spine, reducing the risk of complications and the most conducive to bone fusion under whole-body vibration is urgent to know.ObjectivesThis study researched the best approach under vibration by comparing the effects of four different approaches on the spine, especially regarding some significant indexes related to complications and outcomes.MethodsThe L1-L5 finite element model was modified to simulate anterior, posterior, trans-foraminal and direct lateral lumbar interbody fusion approaches with bilateral pedicle screw fixation at L4-L5 level.FindingsAnterior lumbar interbody fusion decreased the corresponding vibration amplitude of the dynamic response at adjacent segments compared with the other three approaches. Direct lateral lumbar interbody fusion decreased the maximum stress in the cage, the endplates at the fused level, and the maximum compressive stress at the interface between the cage and endplates. The maximum disc height and segmental lordosis of Direct lateral lumbar interbody fusion model were the highest among these fusion approaches.InterpretationAnterior lumbar interbody fusion may provide a more stable environment for the adjacent segments under vibration. Direct lateral lumbar interbody fusion may reduce the risk of subsidence, cage failure, and adjacent segment disease. Direct lateral lumbar interbody fusion may provide a more stable and suitable environment for vertebral cell growth and lead to better fusion outcomes. The findings may help us understand the effect of various fusion approaches on lumbar and provide some references for choosing a fusion approach.     

Biomechanical testing of different posterior fusion devices on lumbar spinal range of motion

BackgroundRecent minimal-invasive posterior fusion devices are supposed to provide stability and obtain fusion in combination with interbody cages in the instrumented segment. The aim of the present study is to evaluate the primary stability of two minimal-invasive posterior prototypes compared to an established spinous process plate and standard pedicle screw instrumentation.MethodsSeven fresh frozen human cadaver lumbar spines (L2–L5) were tested in a spinal testing device with a moment of 7.5 Nm. Spinal stability was determined as mean range of motion (RoM) in the segment L3/L4 during extension-flexion, lateral bending and axial rotation. The RoM was measured during five conditions: 1. intact; 2. working prototype composed of an interspinous device and process plates; 3. an established spinous process fixation device 4. working prototype of facet fixation and 5. pedicle screw fixation.FindingsAll devices caused a significant reduction of RoM during extension-flexion. The RoM during lateral bending was significantly reduced to 37% (of intact) by pedicle screws and 68% by facet fixation prototype. During axial rotation the RoM was significantly reduced to 52% by pedicle screws and to 86% by facet fixation prototype. The other devices had no significant influence on RoM during lateral bending and axial rotation.InterpretationThe facet fixation prototype provided less primary stability compared to pedicle screws, but had significant advantages over spinous process fixation techniques. The results encourage further testing of this implant as a minimal-invasive approach for posterior fixation.     

以三维有限元分析两种方法L4／5椎间融合后的螺钉应力

背景：作者未查及使用乏维有限元方法分析椎弓根螺钉内阚定并自体髂召’植骨或椎间融合器植骨后螺钉应力情况的相关报道。目的：在L4～L5节段有限元模型上建立椎弓根螺钉内吲定并椎间双枚椎间融合器置入和椎弓根螺钉内固定并椎间自体髂骨植骨的模型,分析两种不同方法植骨后螺钥的应力分布情况。方法：选择1名健康男性,年龄20岁,借助CT扫描和有限元软件,建立L4-Ls节段的三维有限元模型。在验证有效的模型上建立后路椎弓根乍钉棒系统内固定＋双枚椎间融合器植骨模型（模型A）和后路椎弓根钉棒系统内固定＋椎间自体髂骨植骨有限元模型（模型B）,然后在各模型上分别施加载倚,观察螺钉应力分布情况。结果与结论：建立两种不同后路内固定并植骨融合术式三维有限元模型,在不同载荷情况下,发现模型B螺钉应力值均大于模型A,且差异具有显著性意义（P〈0.05）,差值最大部位为螺钉尾部。结果提示后路椎弓根钉棒系统内固定＋椎间自体骼骨植骨后更容易出现椎弓根螺钉断裂情况。     

Cage椎弓根内固定联合自体颗粒骨打压植骨的即时生物力学稳定性

背景：自体骨移植结合椎间融合器联合椎弓根螺钉常运用于椎体融合,但单纯颗粒骨打压联合椎弓根钉的临床生物力学研究报道不多。目的：比较后路自体颗粒骨打压植骨内固定及Cage内固定的即时生物力学稳定性。方法：利用腰椎后路附件逐级破坏和椎间盘切除制作腰椎不稳模型。12具猪腰椎标本随机分为两组：打压植骨结合椎弓根螺钉内固定组（实验组）,Cage结合椎弓根螺钉内固定组（对照组）。使用脊柱三维运动测试机模拟人体对两组标本在正常、不稳、融合3个状态下进行前屈、后伸、左右侧屈、左右旋转等各个活动的生物力学测试,三维激光扫描仪测定不同载荷下不稳节段的运动范围。结果与结论：正常状态下,两组间L2～3节段各方向运动范围差异无显著性意义（P〉0.05）,说明两组标本均衡性好,具有可比性;与正常状态相比,两组不稳状态各方向运动范围亦明显增加（P〈0.05）;融合后对照组L2～3节段椎间各方向运动范围均较实验组小,但差异无显著性意义（P〉0.05）。说明自体颗粒骨打压植骨内固定与Cage内固定均能明显提高脊柱的即时生物力学稳定性,而且两组对于改善脊柱稳定性无显著性差异。     

原位及复位融合腰椎滑脱的三维有限元分析

背景：由于脊柱结构复杂,对复位或原位融合后融合的腰椎节段应力分布变化特点的精确生物力学分析一直是个难点。目的：通过建立b5节段退变性滑脱原位椎间融合椎弓根钉内固定和复位椎间融合椎弓根钉内固定的三维有限元模型来比较腰椎滑脱原位融合和复位融合两种手术方式在各种载荷下的生物力学变化及其对腰椎稳定的影响。方法：根据健康成年男性的下腰椎CT数据,利用mimics,Catia和Patran,Marc等软件建立起b5节段的三维有限元模型,利用此模型模拟退变性腰椎滑脱,在此基础上建立L4／5节段原位椎间融合椎弓根钉内固定和复位椎间融合内固定模型,分析两模型在各种载荷下的应力分布特点,并比较异同。结果与结论：L舶节段退变性滑脱原位椎间融合椎弓根钉内固定和复位椎间融合椎弓根钉内固定三维有限元模型在前屈后伸侧屈旋转负荷下,该节段各部结构,包括椎体,椎弓根钉内固定器和椎问融合器上的应力变化没有显著差异。两模型都显示椎间融合器和椎弓根螺钉内固定器上分布的应力最大。结果表明退变性腰椎滑脱,行原位椎间融合内固定和复位椎间融合内固定后,复位与否对该节段生物力学没有显著影响。     

Mechanical behavior of fixation components for periprosthetic fracture surgery

BackgroundReliable periprosthetic fracture treatment needs detailed knowledge on the mechanical behavior of the fixation components used. The holding capacity of three conventional fixation components for periprosthetic fracture treatment was systematically investigated under different loading directions.MethodsLocking compression plates were fixed to a 7 cm long part of diaphyseal fresh frozen human femur with either a single 1.7 mm cerclage cable, a 5.0 mm monocortical or a bicortical locking screw (n = 5 per group). Constructs were loaded in lateral, torsional and axial direction with respect to the bone axis in a load-to-failure test. Corresponding stress distribution around the screw holes was analyzed by finite element modeling.FindingsBoth screw fixations revealed significantly higher stiffness and ultimate strength in axial compression and torsion compared to the cerclage (all P < 0.01). Ultimate strength in lateral loading and torsion was significantly higher for bicortical screws (mean 3968 N SD 657; mean 28.8 Nm SD 5.9) compared to monocortical screws (mean 2748 N SD 585; mean 14.4 Nm SD 5.7 Nm) and cerclages (mean 3001 N SD 252; mean 3.2 Nm SD 2.0) (P ≤ 0.04). Stress distribution around the screw hole varied according to the screw type and load direction.InterpretationFixation components may be combined according to their individual advantages to achieve an optimal periprosthetic fracture fixation.     

单侧椎弓根钉固定结合椎间融合治疗腰椎间盘突出症

背景：脊柱双侧内固定广泛应用于治疗腰椎退行性疾病,但长期随访发现坚强内固定形成的应力遮挡效应会导致融合椎体的骨量丢失以及临近椎体退变加速。目的：观察单侧椎弓根螺钉内固定椎间融合治疗腰椎间盘突出症的临床效果。方法：2006-01/2010-01江苏大学附属武进医院对45例一侧肢体为主要症状的腰椎间盘突出症患者进行经椎间孔后路椎间融合单侧椎弓根螺钉内固定。结果与结论：45例患者均获得随访,随访时间6～24个月。全部切口均一期愈合,未发生切口感染。JOA评分和目测类比疼痛评分两项指标均有显著改善,固定后及末次随访与固前相比,差异有显著性意义（P〈0.01）。45例患者中优36例,良5例,可4例,优良率为91%。6个月后X射线及CT提示椎间融合,椎间融合器无移位,无沉降,内固定无松动、断裂。提示单侧神经减压椎间融合和单侧椎弓根螺钉固定是可行的脊柱外科技术,治疗腰椎间盘突出症可获得满意的临床效果。     

单双侧椎弓根螺钉椎体问融合术治疗腰椎退行性疾病的疗效比较

目的 比较单、双侧椎弓根螺钉椎体间融合术治疗腰椎退行性疾病的临床疗效.方法 2006年10月至2010年10月采用后路椎体间融合椎弓根螺钉固定治疗资料完整的60例腰椎退行性疾病患者,根据固定方式分为A、B两组.A组应用单侧椎弓根螺钉椎体间融合术治疗28例,男16例,女12例;年龄40～56岁,平均48岁.术前诊断:腰椎椎间盘脱出4例,腰椎椎间盘术后复发6例,腰椎管狭窄症6例,腰椎退行性不稳8例,退行性腰椎滑脱症4例.B组应用双侧椎弓根螺钉椎体间融合术治疗32例,男18例,女14例;年龄42～67岁,平均52岁.术前诊断:腰椎椎间盘脱出5例,腰椎椎间盘术后复发6例,腰椎管狭窄症7例,腰椎退行性不稳6例,退行性腰椎滑脱症8例.使用ODI评分、VSA视觉模拟评分对两组患者术前评分及术后评分,并比较两组的手术时间、失血量、融合率、医疗费用、手术优良率、并发症发生率等情况.结果 两组患者ODI评分、VSA视觉模拟评分术前与术后3个月、6个月比较差异有统计学意义(PO 05),两组融合率分别为92%、94%.结论 单、双侧椎弓根螺钉椎体间融合术治疗腰椎退行性疾病临床疗效均满意,单侧椎弓根螺钉椎体间融合术创伤小,经济简便,是治疗腰椎退行性疾病的较好选择;但应严格掌握手术适应证,长期疗效尚需进一步临床研究.     

Interpedicular kinematics in an in vitro biomechanical assessment of a bilateral lumbar spondylolytic defect

BackgroundA spondylolytic defect in lumbar vertebra is a common condition during early childhood and adolescence, and is considered a precursor to spondylolisthesis. This study examined whether a bilateral spondylolytic defect in lumbar spine intrinsically results in increased intervertebral translations during different bending motions.MethodsSeven fresh frozen cadaveric kangaroo lumbar (L1–L6) spine specimens were tested in a kinematic spine simulator; first in their intact state, followed by creating a bilateral spondylolytic defect at L4 and retesting. In addition to recording global and segmental range of motions, the pedicles at L3, L4, and L5 vertebrae were digitized bilaterally and virtually tracked throughout testing. Interpedicular kinematic metrics were employed to capture any changes in translatory motions during flexion–extension, bilateral bending, and axial torsion testing modes.FindingsFollowing the defect, range of motion at the defect level (L4–L5) increased significantly in all the three motion planes. At L4–L5, normalized interpedicular displacement increased significantly in flexion–extension (median change + 156%) and bilateral bending (median change + 58%) motions, but changes in bending-plane and out-of-plane intervertebral translations were not significant in any of the testing modes.InterpretationIn the absence of any significant changes in bending-plane and out-of-plane intervertebral translations at L4–L5, changes in interpedicular displacement would directly correspond with the stretching of posterior annulus of the L4–L5 intervertebral disc. A bilateral spondylolytic defect at L4 may result in significant overstretching of the posterior annulus of the L4–L5 disc during flexion–extension and bilateral bending motions.     

空心椎弓根螺钉置入结合小切口后路腰椎融合治疗腰椎间盘突出症

背景：经皮椎弓根螺钉技术的优点在于可有效减少置钉操作对椎旁肌的过度损伤,有利于患者术后的腰背肌功能恢复,其微创技术操作可避免传统开放手术创伤大,出血多等缺陷。可折断U形长尾空心椎弓根螺钉为中空设计,撑开效果良好,内固定后应力强度、压缩时间、弯曲刚度和扭转力学性能均得到临床验证。目的：观察可折断U形长尾空心椎弓根螺钉系统置入结合小切口后路腰椎椎体间融合治疗单节段腰椎间盘突出症的临床效果。方法：纳入2012年1至12月间因腰椎间盘突出症接受可折断U形长尾空心椎弓根螺钉系统置入结合小切口后路腰椎椎体间融合治疗的患者30例。术后随访12个月,通过患者腰腿疼目测类比评分、Oswestry功能障碍指数以及影像学指标评估临床治疗效果。结果与结论：患者术前目测类比评分及Oswestry功能障碍指数分别为（7.3±0.7）分和71.4±7.1;术后第3天分别为（2.9±0.7）分和29.8±3.6,与术前相比差异有显著性意义;至术后12个月时,低水平目测类比评分及Oswestry功能障碍指数未发生显著改变。术后短时间随访发现,病例术后1年椎间融合良好,无内固定失败或感染等并发症发生。提示可折断U形长尾空心椎弓根螺钉系统置入结合小切口后路腰椎椎体间融合治疗腰椎间盘突出症的临床效果良好,椎间融合率高,手术并发症发生率低,创伤小。     

经微创通道单侧椎弓根置钉联合经椎间孔入路腰椎体间融合术治疗腰椎间盘突出症

目的探讨经Quadrant微创通道单侧椎弓根置钉联合单枚cage经椎间孔入路腰椎体间融合术在腰椎间盘突出症中的疗效及并发症的预防。方法对31例腰椎间盘突出症患者采用全层切开法实施经Quadrant微创通道单侧椎弓根置钉联合单枚cage经椎间孔入路腰椎体间融合术。观察手术时间、出血量、切口长度、住院时间及术后并发症情况。应用视觉模拟评分系统(VAS)评定患者术前和末次随访时的疼痛程度;末次随访采用正、侧位X线片判定植骨融合率及椎间高度,并按Nakai标准评定临床疗效。结果手术时间82~180 min,平均100 min;术中出血90~200 mL,平均120 mL;切口长度3~6 cm,平均4.5 cm;住院时间5~14 d,平均7 d;术后未出现切口区明显皮缘坏死,伤口感染等并发症。所有患者获随访,平均随访时间8个月(3~16个月)。随访期间未见椎弓根钉棒松动、断裂;末次随访疼痛VAS评分由术前(7.1±1.3)分降至(2.3±1.6)分,椎间融合率93.3%,椎间隙高度前缘由术前(1.31±0.33)cm升高到术后(1.54±0.21)cm,后缘由术前(0.55±0.11)cm升高到术后(0.65±0.10)cm。临床疗效:优15例,良11例,可5例,优良率83.87%。结论经微创通道单侧椎弓根置钉联合经椎间孔入路腰椎体间融合术具有手术时间短、出血少、对人体正常组织结构破坏小、治疗费用低等优点;全层切开法对于预防皮缘坏死,脂肪液化具有良好的临床效果。