Motion characteristic of the normal lumbar spine in young adults: instantaneous axis of rotation and vertebral center motion analyses

To determine the motion characteristic of the normal lumbar spine, 61 of 612 optimal radiographs of healthy young Japanese adults in the neutral erect, active maximum flexion and maximum extension positions were carefully selected. The coordinates of the instantaneous axis of rotation (IAR) and vertebral center from L1 to L5 vertebra were analyzed. The directional shifts in IAR in the x-axis and the y-axis closely reflected translational and rotational movements of the vertebra. The IAR showed qualitative values with very large, 95%, probability ellipses in the normal lumbar spine. Analysis of coordinates of the vertebral center provided quantitative data of the extension-to-flexion motion of each vertebra. In extension-to-flexion motion, the L4 vertebra showed a translation-predominant motion characteristic. The L5 vertebra had a rotation-predominant motion characteristic. The patterns of motion of the L1-L4 vertebrae were correlated to the intervertebral disc height and the inclination angle of the facet joint. The L5 vertebra alone showed some specific patterns suggestive of the involvement of a separate ligamentous stabilizer, the iliolumbar ligaments, which reduces translation.     

Geometry of the vertebral bodies and the intervertebral discs in lumbar segments adjacent to spondylolysis and spondylolisthesis: pilot study

The objective is to evaluate the geometric parameters of vertebral bodies and intervertebral discs in spinal segments adjacent to spondylolysis and spondylolisthesis. This pilot cross-sectional study was an ancillary project to the Framingham Heart Study. The presence of spondylolysis and spondylolisthesis as well as measurements of spinal geometry were identified on CT imaging of 188 individuals. Spinal geometry measurements included lordosis angle, wedging of each lumbar vertebra and intervertebral disc. Last measurements were used to calculate ΣB, the sum of the lumbar L1–L5 body wedge angles; and ΣD, the sum of the lumbar L1–L5 intervertebral disc angles. Using Wilcoxon–Mann–Whitney test we compared the geometric parameters between individuals with no pathology and ones with spondylolysis (with no listhesis) at L5 vertebra, ones with isthmic spondylolisthesis at L5–S1 level, and ones with degenerative spondylolisthesis at L5–S1 level. Spinal geometry in individuals with spondylolysis or listhesis at L5 shows three major patterns: In spondylolysis without listhesis, spinal morphology is similar to that of healthy individuals; In isthmic spondylolisthesis there is high lordosis angle, high L5 vertebral body wedging and very high L4–5 disc wedging; In degenerative spondylolisthesis, spinal morphology shows more lordotic wedging of the L5 vertebral body, and less lordotic wedging of intervertebral discs. In conclusion, there are unique geometrical features of the vertebrae and discs in spondylolysis or listhesis. These findings need to be reproduced in larger scale study.     

Biomechanical and clinical study on screw hook fixation after direct repair of lumbar spondylolysis

Objective : To evaluate the biomechanical effect and clinical results of hook screw fixation after direct repair of lumbar spondylous defects in the pars interarticularis. Methods: L2-L6 spines of 8 fresh-frozen and thawed calf cadavers were used for mechanical testing. Bilateral spondylous defects were created in the L4 vertebra. The intervertebral rotation ranges between L4 and L5 were scanned and computerized in various states of motion, such as flexion/extension, lateral bending and torsional loadings applied on the intact spine and the spondylous spine when the spondylous spine was fixed with modified Scott' s fixation, hook screw fixation and Buck ' s fixation sequentially and respectively. Between July 2002 and February 2004, 14 young male patients (aged 15-31 years) suffering from symptomatic lumbar spondylolysis were treated with TSRH hook screw fixation after direct repair of the defects. MacNab criteria were used to assess their pre-and post-operative status. Results: Each fixation technique could significantly increase the intervertebral rotational stiffness and made the stiffness return to nearly the intact level. Hook screw technique provided more rotational stability than the others. Hook screw and Buck' s techniques provided more flexion/extension stability than modified Scott' s technique. Neither complication nor instrumental failure was observed in this study. The mean follow-up period was 21 months. All the patients except one acquired union during the follow-up period. Thirteen patients had a“good”or“excellent”result according to MacNab criteria. Conclusions: Hook screw fixation shows biomechanical advantages and is safe and effective for young patients with lumbar spondylolysis.     

Lumbar instability: a dynamic approach by traction-compression radiography

Translatory segmental instability was provoked by successive axial traction and compression of the lumbar spine in 117 patients with a known spondyl- or retro-olisthetic displacement. Lateral spot radiography showed an anteroposterior translatory movement of 5 mm or more in 24 of 45 patients with lytic spondylolisthesis of L5, in all of 7 patients with degenerative spondylolisthesis of L4, and in 37 of 65 patients with a retro-olisthetic displacement of L3, L4, or L5. In cases of spondyl- and retro-olisthetic instability the upper vertebra moved posteriorly during traction and anteriorly during compression. Severity of low-back pain (LBP) symptoms did not show any correlation with the degree of the maximal displacement but correlated significantly with the amount of instability both in the case of spondyl- and retro-olisthesis. Traction-compression radiography proved a simple and practical method to diagnose and measure translatory segmental instability even when conventional flexion-extension load failed to provoke any abnormal movement (eg, in the case of spondylolisthesis).     

腰椎滑脱发生部位性别年龄的分布特征

目的探讨腰椎滑脱好发部位、性别、年龄的分布特征。方法随机取我院（同济医院）骨科2000年1月至2006年12月期间腰椎滑脱手术病例共149例,剔除合并脊柱外伤、先天、手术后、病理性疾病等12例,对其余137例从发病部位、性别、年龄等各方面进行统计学分析。结果女性退行性腰椎滑脱总的发病数是男性的2.48倍;男女各年龄段不同部位、性别腰椎滑脱发病数呈非正态性分布;L4峡部裂性滑脱平均年龄与L5峡部裂性滑脱平均年龄之间有显著性差异;腰椎退行性滑脱发生的平均年龄为51.88岁,比峡部裂性滑脱（46.47岁）发生晚,两者有显著性差异。结论腰椎滑脱发生性别、年龄有显著性差异。女性退行性滑脱的发生率大于男性,40~60岁为腰椎滑脱的高发时段,峡部裂组发生平均年龄早于退行变组。     

Lumbar trapezoid plate for lumbar spondylolisthesis. A clinical study on preoperative and postoperative instability

The authors studied the effects of a "lumbar trapezoid plate" (spinal plate and pedicle screwing), performed for lumbar spondylolisthesis, observing the effect on the remaining adjacent discs with regard to preoperative and postoperative instability. The authors examined changes in preoperative and postoperative lumbar ROM (range of motion), displacement of motor unit levels, and occurrence of instability in the remaining discs, such as horizontal and rotational displacement, in 26 patients who were followed up for a mean of 29 postoperative months; 13 patients had spondylolytic spondylolisthesis and 13 patients degenerative spondylolisthesis. The authors studied the effects of the fused vertebral angle and reduction of spondylolisthesis on the remaining upper and lower adjacent discs and the preoperative and postoperative fused disc heights. Intervertebral fusion must affect the remaining adjacent discs, but compensatory function of the remaining motor unit level was more influenced by the fused intervertebral angle than by repositioning of the spondylolisthesis. Fusion at a physiologically lordotic position is quite necessary. For this purpose, it is considered important to prevent grafted bones of the posterior lumbar interbody fusion (PLIF) from collapse and to maintain the achieved alignment of the lumbar spine.     

Global spinal motion in subjects with lumbar spondylolysis and spondylolisthesis: does the grade or type of slip affect global spinal motion?

STUDY DESIGN: This was a prospective pilot study to investigate the global motion characteristics of the spondylolysis and spondylolisthesis populations. OBJECTIVES: The aim of this study is to determine the influence of a spondylolisthesis or a spondylolysis on global spinal motion and to establish whether this is dependent on the cause of the slip or the degree/grade of the slip. SUMMARY OF BACKGROUND DATA: The condition of spondylolisthesis has been extensively discussed in the literature with respect to its etiology and management. However, the mechanics and movement of the spine in relation to pathology and the effect of this condition on function have received scant attention. METHODS: The motion of the lumbar spine was investigated in 31 patients (19 men, 12 women, mean age 47.7 +/- 17.8 years) who were diagnosed as having either a lumbar spondylolysis or a spondylolisthesis. These patients were compared with a preexisting database of 203 normal subjects (100 men, 103 women, mean age 39.8 +/- 13.4 years). Patients were graded according to the type of spondylolisthesis or spondylolysis they had, and the extent of slip was rated using Meyerding's classification (1932) and measured directly using methods of Boxall et al (1979) and Wiltse et al (1983). RESULTS: Direct measurements of the extent of slip using Boxall et al (1979) and Wiltse et al (1983) methods were found to have no significant correlation with the resultant range of motion (ROM) or the speed of movement. This study suggests that motion parameters are influenced by the grade of slip in patients with spondylolisthesis, and the type of spondylolisthesis i.e., whether isthmic or degenerative. In the A-P flexion-extension plane, the results indicate that subjects with a defect only, i.e., a spondylolysis, and thus no slip present with a spinal hypermobility (P < 0.01). Subjects with an isthmic slip tend to be either slightly hypermobile or within the anticipated range of motion, whereas those subjects with a degenerative slip tend to be hypomobile (P < 0.05). Movements into lateral flexion were restricted in both the isthmic and degenerative spondylolisthesis patients, whereas rotation was only influenced by the level at which the defect occurred. In terms of degree of displacement, in higher grades of displacement, there was a trend towards hypermobility. CONCLUSIONS: The findings of this study suggest that the grade and type of spondylolisthesis do influence global motion parameters. This information may be useful in the clinical assessment of this patient group.     

腰椎滑脱部位性别年龄的关系分析

目的 :探讨腰椎峡部裂滑脱和退行性滑脱在发生部位、好发年龄和性别分布三方面差异。方法 :随机取 2 0 0 1年 1月～ 2 0 0 4年 1月期间手术的峡部裂滑脱和退行性滑脱共 76例 ,从发病部位、性别、年龄三方面进行统计学分析。结果 :腰椎滑脱不同类型在滑脱部位方面存在显著性差异 ,L5峡部裂发病率高于L4,L4退变性滑脱发病率高于L5。不同性别在滑脱部位方面无显著性差异。 40～ 5 0岁为腰椎滑脱的高发时段 ,退变组平均年龄大于峡部裂组。结论 :腰椎峡部裂滑脱和退行性滑脱在发生部位、好发年龄、性别分布三方面存在差异 ,为鉴别诊断和治疗提供帮助。     

椎板回植椎弓根钉系统一体化固定治疗腰椎滑脱伴神经损伤

目的探讨采用椎板回植与椎弓根钉系统一体化固定腰椎滑脱合并神经损伤手术中的疗效。方法应用椎板回植与椎弓根钉系统一体化固定技术治疗腰椎滑脱合并神经损伤53例,L3~4滑脱4例,L4~5滑脱29例,L5~S1滑脱20例,退行性滑脱37例,单节段峡部崩裂性滑脱16例。结果53例均随访3年以上(3年8个月~7年2个月),全部病例回植椎板均在术后3~4个月达到良好的骨性融合,无对神经产生新的压迫,无症状复发和腰椎滑脱加重。结论椎板回植与椎弓根钉系统一体化固定在治疗腰椎滑脱合并神经损伤应用中操作简单、安全、可靠,具有恢复局部结构和维持脊柱稳定性的特点。     

Degenerative lumbar instability

The degenerative process typically results in a stiff but stable lumbar spine; however, occasionally instability may result. The primary forms of degenerative lumbar instability are spondylolisthesis, which is a translation of a single vertebra over another or a more global degenerative scoliosis. All forms of lumbar instability can result in back pain and neural compression. Most forms of degeneration that result in instability are self-limited and can be treated through non-operative means; however, some forms may be progressive and significantly symptomatic so that patients will require surgery.     

Three dimensional finite element analysis of the pediatric lumbar spine. Part II: biomechanical change as the initiating factor for pediatric isthmic spondylolisthesis at the growth plate

A non-linear 3-dimensional finite element pediatric lumbar spine model with vertebral growth plate and apophyseal bony ring was developed. Lumbar spondylolysis was simulated in the model. The Von Mises stresses in the structures surrounding the vertebral growth plate, including apophyseal bony ring and osseous endplate were calculated in various loading modes. Instantaneous axis of rotation (IAR) path from flexion to extension was also analyzed. The results were compared with those of the intact model and the literature. The IAR path was at the posterior disc-endplate space of the lower vertebra in the intact spine, and moved cranially towards the upper-posterior disc space in the lytic spine. This was in agreement with in vivo radiological data by Sakamaki et al. [19]. During various loading modes, stresses in the spondylolytic pediatric model were higher than that of the intact model; ranging from 1.1 to 6.0 times, with the highest value in extension at the growth plate. In conclusion, FE models indicate that stress concentrations in the lytic model increase at the growth plate which may lead to physis stress fracture leading to spondylolisthesis.Part I of this article can be found at http://dx.doi.org/ 10.1007/s00586-005-1026-z     

Using cineradiography for continuous dynamic-motion analysis of the lumbar spine

STUDY DESIGN: Cineradiography was used to analyze continuous dynamic motion in the lumbar spine. OBJECTIVES: To identify motion patterns of the lumbar spine in asymptomatic volunteers and symptomatic patients with L4 degenerative spondylolisthesis, and to use the findings to discuss segmental instability in this disorder. SUMMARY OF BACKGROUND DATA: The use of radiographic findings to assess lumbar spine instability remains controversial. Although some studies have reported on lumbar kinematics during actual movement, the motion patterns in asymptomatic volunteers and symptomatic patients with L4 degenerative spondylolisthesis have not been fully clarified. METHODS: While asymptomatic volunteers (n=20; mean age, 27; control group) and symptomatic patients with L4 degenerative spondylolisthesis (n=41; mean age, 63; degenerative spondylolisthesis [DS] group) flexed from a sitting neutral position and back to the neutral position (flexion course), cineradiography was used to record lateral segmental lumbar motions. Twelve frames were selected during the flexion course, and flexion-extension angle (f-e angle) and translation in the sagittal plane were measured at each motion segment (L2-L3, L3-L4, L4-L5, and L5-S1). The DS group was classified into 2 subgroups according to percentage of slip: DS group I, with a slip equal to or less than 15%; and DS group II, with a slip of more than 15%. The motion pattern was compared between the groups. RESULTS: In the control group, f-e angle and translation at the L2-L3, L3-L4, and L4-L5 segments moved simultaneously, although the L5-S1 segment showed an initial delay. The amount of f-e angle and translation changed almost symmetrically. In both f-e angle and translation, the L4-L5 segment showed a large motion pattern. In DS group I (n=21), the L4-L5 segment showed a large motion pattern in f-e angle and an intermediate motion pattern in translation. In DS group II (n=20), the L4-L5 segment showed an intermediate motion pattern in f-e angle, and a small motion pattern in translation. The relative range of f-e angle at the L4-L5 segment had the largest range in DS group I, and the relative translation showed a serial decrease from the control group through DS group II. A significant correlation between f-e angle and translation (harmonious motion pattern) was noted at the L2-L3, L3-L4, and L4-L5 segments in the control group. The harmonious motion pattern at the L4-L5 segment was significantly less in the DS group than in the control group. The loss of harmonious motion pattern (disordered motion pattern) at L4-L5 was well-revealed in the DS group II. CONCLUSIONS: Motion analyses using cineradiography helped to explain the phenomena of lumbar spine kinematics. Based on continuous dynamic-motion analysis with cineradiography, large f-e angle and disordered motion pattern during the flexion-backward course in the DS group I was considered to be caused by segmental instability. The decreased translation and disordered motion pattern throughout the flexion course in the DS group II was considered to be caused by restabilization.     

退行性腰椎不稳发病相关因素的临床研究

目的分析性别、年龄、相应节段椎间盘退变、小关节突骨关节炎以及椎体滑脱与退行性腰椎不稳的相关性。方法行腰椎MRI及站立位过伸过屈侧位片检查,观察L1-S15个运动节段的椎间盘退变、椎间小关节退变以及有无椎体滑脱。腰椎不稳分为前水平位移不稳．后水平位移不稳和角度不稳。椎间盘退变分四度。小关节突退变分为4级。腰椎滑脱分四度。将结果进行Spearman等级相关分析。结果前向水平不稳与椎间盘退变呈正相关,与椎间小关节骨关节炎呈负相关,与椎体滑脱呈正相关;后向水平不稳与年龄呈正相关,与椎间盘退变呈正相关。与椎间小关节骨关节炎呈正相关,与椎体滑脱没有明显相关性。结论退行性腰椎不稳与多种因素具有显著相关性,但腰椎滑脱不一定有不稳。     

Association of incipient disc degeneration and instability in spondylolisthesis

Summary The concurrence of early disc degeneration and abnormal segmental motion in spondylolysis of young low back pain patients (n = 14) was investigated using magnetic resonance imaging (MRI) and flexion-extension radiography. Seven patients with L5 spondylolisthesis had normal discs on MRI and 7 had disc degeneration below the slipped vertebra. The parallel motion, angular mobility and centre of motion were similar in the degenerated discs and in normal discs. The present study shows that in adolescents the motion pattern and hydration of discs associated with spondylolysis and spondylolisthesis are not always abnormal. The early dehydration and degeneration of lumbar discs observed on MRI are not always associated with abnormal mobility of the corresponding motion segment.     

腰椎经皮内镜双侧椎间孔一次成形的有限元分析

目的 采用有限元分析法分析腰椎经皮内镜双侧椎间孔一次成形对腰椎生物力学的影响.方法 选取1例健康成年男性志愿者,通过腰椎CT三维重建检查获取腰椎CT数据,通过Solidworks 15.0软件建立椎间盘及关节软骨模型,建立正常L4,5椎体三维有限元模型(A模型).模拟双侧椎间孔入路经皮内镜腰椎间盘切除术过程,在A模型的...     

Telamon融合技术在下腰椎不稳治疗中的作用

目的回顾性分析了Telamon融合技术在治疗下腰椎不稳定方面的作用。方法本组共68例,均为单节段病变,平均年龄49岁,腰椎椎弓崩裂伴滑脱者27例,腰椎退变性不稳者41例,术前病程平均28．6月,Oswestry残疾指数平均48．5%。所有病例均行后路减压、椎弓根螺钉内固定及Telamon椎体间融合术,其中全椎板切除者5例,双侧椎板间扩大开窗者63例。结果术后随访平均11．8个月,最后随访时Oswestry残疾指数平均7．5％,复查X线片均获良好的骨性融合,无明显不稳定征象。结论Telamon融合技术能提供良好的骨性融合并维持良好的椎体间高度和腰椎的生理性前凸,由于其本身并不具有即刻稳定性,故应在坚强内固定的保护下应用,获得良好效果的关键在于正确的手术适应证。     

Kinematics of the lumbar spine in trunk rotation: in vivo three-dimensional analysis using magnetic resonance imaging

In vivo three-dimensional (3D) kinematics of the lumbar spine has not been well evaluated by the conventional methods because of their methodological limitations, while 3D intervertebral motions have been quantitatively determined by cadaver studies. We thus developed a novel 3D analyzing system for the relative motions of individual vertebrae using 3D magnetic resonance imaging (MRI) and analyzed in vivo 3D intervertebral motions of the lumbar spine during trunk rotation. Ten healthy volunteers underwent 3D MRI of the lumbar spine in nine positions with 15° increments during trunk rotation (0°, 15°, 30°, 45°, and maximum). Relative motions of the lumbar spine were calculated by automatically superimposing a segmented 3D MRI of the vertebra in the neutral position over images of each position using the voxel-based registration method. These 3D motions were represented with 6 degrees of freedom by Euler angles and translations on the coordinate system. The mean axial rotation of ten healthy volunteers of each lumbar spinal segment in 45° trunk rotation to each side ranged from 1.2° to 1.7°. Coupled flexion with axial rotation was observed at the segments from L1/2 to L5/S1. Coupled lateral bending of the segments from L1/2 to L4/5 was in the opposite direction of the trunk rotation, while that of T12/L1 and L5/S1 was in the same direction. The direction of the coupled lateral bending in the present study was different from that in the previous cadaver study only at L4/5. This difference might result from the non-load state of the supine position in the current study and/or the non-physiological state in the cadaver study. Our system has two limitations: (1) the study was conducted with each volunteer in the supine position, and (2) because the rotation device regulated trunk rotation, trunk rotation might not have been physiological. In vivo 3D intervertebral motions of the lumbar spine during trunk rotation were evaluated using our novel motion analysis system. These data may be useful for the optimal orthopaedic management of lumbar spinal disorders. Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users.     

Biomechanical comparison of spondylolysis fixation techniques

STUDY DESIGN: A load-controlled biomechanical analysis of flexion, extension, and torsional stiffness in instrumented calf spines. OBJECTIVES: To compare biomechanically the performance of various fixation techniques for the repair of spondylolytic defects in the pars interarticularis. SUMMARY OF BACKGROUND DATA: Several techniques have been developed to stabilize a spondylolytic defect in the lumbar spine. There are, however, no comprehensive biomechanical studies in which these techniques are compared. METHODS: Nine fresh-frozen and thawed calf cadaveric lumbar L2-L6 spines were used for mechanical testing. Scott's technique, Buck's technique (screw fixation in the lamina across the defects), modified Scott's technique (wire loops around cortical screws placed into both pedicles and tightened under the spinous process), and screw-rod-hook fixation were applied on the calf lumbar spines in which bilateral spondylolytic defects were created in the L4 vertebra. Motion across the defects for each direction of loading in flexion, extension, and rotation was measured using extensometers. The intervertebral rotations and the strain at the site of the spondylolytic defect were computed from the acquired load-displacement data. RESULTS: Each fixation technique significantly increased stiffness and returned the intervertebral rotational stiffness to nearly intact levels. Displacement across the defect under flexion loading was significantly suppressed by each instrumentation technique, but the least motion (P < 0.05) was allowed with the screw-rod-hook fixation or Buck's technique. CONCLUSIONS: All four fixation techniques restored the intervertebral rotational displacements under flexion and torsional loading to the intact condition. The screw-rod-hook fixation allowed the least amount of motion across the defect during flexion.     

成人峡部裂性腰椎滑脱病理进展的初步探讨

目的:探讨成人峡部裂性腰椎滑脱进展的发生及其产生的原因.方法:随访42例峡部裂和峡部裂性腰椎滑脱患者,据Meyerding滑脱分级,峡部裂而无滑脱患者13例,Ⅰ度滑脱患者29例.全部患者采用非手术治疗或不干预措施.结果:随访2～7年,平均4.3年.依据Boxall滑脱进展指标,11例出现滑脱进展.滑脱节段椎间盘高度降低10%～90%(平均42%).结论:峡部裂性腰椎滑脱在成人中也有一定病理进展,可能与椎间盘退变有关.     

Radiographic evaluation of posterolateral lumbar fusion for degenerative spondylolisthesis: long-term follow-up of more than 10 years vs. midterm follow-up of 2–5 years

Although posterolateral fusion of the lumbar spine without instrumentation has been widely performed for spinal instability caused by degenerative spondylolisthesis in the lumbar spine, few long-term follow-up studies have been reported. We studied ten patients who underwent posterolateral fusion for degenerative spondylolisthesis in the lumbar spine without instrumentation in our hospital, five of whom were followed up for more than 10 years and the other five for 2–5 years. We used radiography to examine their fusion status, instability and degenerative changes at the fusion level, change in the slip, change in lumbar lordosis, and instability and degenerative changes one level above and one level below the fusion. In most of the ten patients, radiographic evaluation demonstrated solid fusion, minimal degenerative changes, and preservation of lumbar lordosis and spinal mobility. Posterolateral lumbar fusion for degenerative spondylolisthesis in the lumbar spine seems promising for obtaining not only good radiographic features but also good clinical results lasting over more than 10 years. Electronic Publication