Posterior distraction forces of the posterior longitudinal ligament stratified according to vertebral level

Introduction Although considered significant in resisting midline intervertebral disc herniation, the posterior longitudinal ligament (PLL) has had relatively few studies performed regarding its morphology and function. We performed the present experiment to discern the amount of posterior tensile force necessary to disrupt the PLL at each vertebral level. Materials and methods Twenty-five adult cadavers underwent laminectomies of vertebrae C1 to S1. After removal of the spinal cord, nerve roots, and dura mater, the PLL was identified for each vertebral level and a steel wire placed around its waist in the midline and a tensile gauge attached and posterior tension applied perpendicular to the spine. Forces necessary to failure of the PLL were noted for each vertebral level. Results The PLL was found to be stronger in the thoracic spine compared to the cervical and lumbar vertebrae (P < 0.05). Dividing the vertebral levels in this manner, we found an average posterior distraction force to failure of 48.3 N in the cervical region, 61.3 N in the thoracic region, and 48.8 N in the lumbar region. Conclusions These findings support clinical observations that thoracic disc herniation is rare. We hypothesize that this clinical observation is partially due to a stronger PLL in the thoracic spine.     

Histological investigation of rabbit ligamentum flavum with special reference to differences in spinal levels

The structure of the ligamentum flavum has yet to be fully elucidated and no studies have investigated fine structural differences at different spinal levels in any animals. The aim of the present study was to clarify structural differences in the ligamentum flavum at different spinal levels (cervical: C3/4 and C5/6; upper thoracic: T2/3; lower thoracic: T9/10; lumbar: L3/4) using light and electron microscopy of rabbit specimens. Light microscopy using resorcin—fuchsin staining revealed that the distribution of elastic fibers was diffuse in the cervical and upper thoracic regions, but was generally dense in the lower thoracic and lumbar regions. Electron microscopy demonstrated that the cervical and upper thoracic regions were rich in collagen fibers. Conversely, the lower thoracic and lumbar regions were rich in elastic fibers. Quantitative image analyses displayed thick elastic fibers in the lower thoracic and lumbar regions, with high area ratios. Radiographic examinations revealed that ranges of motion were large at the cervical region, but small at the lower thoracic and lumbar regions. These findings suggest that structure of the ligamentum flavum varies at different spinal levels with respect to differences in motion.     

椎体成形治疗中聚甲基丙烯酸甲酯骨水泥的应用

背景：经皮椎体成形治疗脊柱血管瘤可栓塞瘤体,增加椎体强度,并具有止痛作用。   目的：分析经皮椎体成形治疗症状性颈、胸、腰椎体血管瘤的临床效果。 方法：选择25例症状性单椎体血管瘤患者,其中颈椎3例,胸椎12例,腰椎10例。均在C型臂X射线机引导下行经皮聚甲基丙烯酸甲脂椎体成形治疗。治疗后摄X射线片观察椎体高度变化及骨水泥分布和渗漏情况,以目测类比评分及Oswesty功能障碍评分评定疼痛缓解及功能恢复情况。 结果与结论：所有手术均顺利完成,未发生脊髓及神经损伤。术中共3节椎体发生骨水泥渗漏,但未出现不适症状。25例患者均获随访10-26个月,疼痛症状均有不同程度改善,治疗后手术椎体高度无明显丢失,椎体无塌陷,血管瘤无复发。表明经皮椎体成形作为治疗症状性椎体血管瘤的理想方法,具有微创、低风险、易恢复、疼痛缓解迅速等优点,但对于椎体皮质有破坏者,需注意骨水泥渗漏的发生。     

兔单椎轴向动态冲击的实验研究

目的通过对兔单椎进行动态冲击破坏试验,并与静态压缩实验进行对比,研究椎体轴向冲击的损伤机制。方法通过落锤动态冲击实验装置,利用示波器和高速摄影获得力传感器的电压波形图和椎体冲击的详细过程。结果胸、腰椎平均静态载荷分别为910、947 N,平均动态载荷分别为1 196、1 026 N;胸、腰椎平均动荷系数分别为1.37和1.08。静载条件下,胸、腰椎平均等效应力为15.28、12.51 MPa;动载条件下,胸、腰椎平均等效应力20.03、13.56 MPa。动态冲击过程中,纵向、横向平均应变分别为-0.3和-0.005(压缩);动载条件下,椎骨的破坏能量从0 J一直增大到4.4 J。结论在动、静态实验条件下,同一椎体动态载荷大于静态载荷;胸椎平均动荷系数大于腰椎;胸椎应力大于腰椎;椎体受到轴向冲击力时纵向应变大于横向应变;椎体能量增长呈现先缓慢后快速的过程。研究结果可以为临床人脊柱椎体损伤的预防和康复提供指导意见。     

Numerical variations in human vertebral column: a case report

Numerical increases in the elements of the vertebral column probably do not occur. In this case, 25 presacral vertebrae (PSV) were determined in the vertebral column of a 22-years-old male skeleton. Their distribution was as follows; 7 cervical, 12 thoracic, 1 thoraco-lumbar, 5 lumbar. Sacrum contained 5 vertebrae. In addition, sacralization or lumbarization was not seen.     

The cat vertebral column: stance configuration and range of motion

This study examined the configuration of the vertebral column of the cat during independent stance and in various flexed positions. The range of motion in the sagittal plane is similar across most thoracic and lumbar joints, with the exception of a lesser range at the transition region from thoracic-type to lumbar-type vertebrae. The upper thoracic column exhibits most of its range in dorsiflexion and the lower thoracic and lumbar in ventroflexion. Lateral flexion is limited to less than 5° at all segments. The range in torsion is almost 180° and occurs primarily in the midthoracic region, T4-T11. Contrary to the depiction in most atlases, the standing cat exhibits several curvatures, including a mild dorsiflexion in the lower lumbar segments, a marked ventroflexion in the lower thoracic and upper lumbar segments, and a profound dorsiflexion in the upper thoracic (above T9) and cervical segments. The curvatures are not significantly changed by altering stance distance but are affected by head posture. During stance, the top of the scapula lies well above the spines of the thoracic vertebrae, and the glenohumeral joint is just below the bodies of vertebrae T3-T5. Using a simple static model of the vertebral column in the sagittal plane, it was estimated that the bending moment due to gravity is bimodal with a dorsiflexion moment in the lower thoracic and lumbar region and a ventroflexion moment in the upper thoracic and cervical region. Given the bending moments and the position of the scapula during stance, it is proposed that two groups of scapular muscles provide the major antigravity support for the head and anterior trunk. Levator scapulae and serratus ventralis form the lateral group, inserting on the lateral processes of cervical vertebrae and on the ribs. The major and minor rhomboids form the medial group, inserting on the spinous tips of vertebrae from C4 to T4. It is also proposed that the hypaxial muscles, psoas major, minor, and quadratus lumborum could support the lumbar trunk during stance. Received: 2 January 1997 / Accepted: 23 September 1997     

New dysostosis showing multilevel absence of vertebral pedicles: unique developmental anomaly of vertebral arches?

We report on an apparently normal child who shows hypopaplasia of the vertebral pedicles and posterior arches of several cervical, thoracic, and lumbar vertebrae with normally fused spinous apophyses, hypoplastic sacrum, lumbar epidural lipomatosis, synostoses of some cervical vertebral disks, and sacral spina bifida. The most likely mechanism is an abnormal differentiation of the spinal processes, due most probably to an absence of differentiation in cartilage of the dense mesenchyme forming their most anterior part. Because the anomalies affect multiple levels, we highly suspect a genetic basis to this unusual dysostosis affecting the development of the posterior sclerotomes.     

Comparison of the structure of human intervertebral discs in the cervical,thoracic and lumbar regions of the spine

Posterior and anterior heights, cross-sectional area and shape were measured for all the intervertebral discs in four spines from elderly human cadavers. Disc height was a minimum at the T4-5 level; thoracic discs were less wedge-shaped than those in the cervical and lumbar regions. Cross-sectional area increased from the cranial to caudal extremity; at the L5-S1 level the nucleus pulposus occupied a high proportion of this area. Cervical discs tended to have an elliptical cross-sectional shape, thoracic discs were more circular and lumbar discs tended to have an elliptical cross-section which was flattened or re-entrant posteriorly. This shape distribution was quantified by defining a shape index which had a maximum value of 1 for a circular cross-section. Orientations of the reinforcing fibres in the outer lamellae of the anterior annulus fibrosus were measured from 27 discs by X-ray diffraction. For these measurements, C3-4, T7-8 and L2-3 were chosen as representative of cervical, thoracic and lumbar discs. The fibre tilt, with respect to the axis of the spine, was significantly less in the cervical discs (at 65 degrees) than in the thoracic and lumbar discs (about 70 degrees). These findings are interpreted in relation to differing functional requirements and possible mechanisms of failure in the cervical, thoracic and lumbar regions of the spine in the light of current knowledge on the biomechanics of the intervertebral disc.     

Changes in the surface of the superior articular joint from the lower thoracic to the upper lumbar vertebrae

Thirty-two human vertebral columns were selected from the Kanazawa Collection at the University of Kanazawa, Japan. The superior articular joint surface was categorised into the thoracic type and the lumbar type, and the pattern of the change from one type to the other in the lower thoracic and upper lumbar region was examined. In 21 of 32 cases (66%), the change from the thoracic to the lumbar type occurred over 2 vertebral segments, either between the 12th thoracic and 1st lumbar vertebrae (44%) or between the 11th and 12th thoracic vertebrae (22%). In the remaining 11 cases (34%), the change occurred over 3 vertebral segments, with a transitional type of articular surface. The change from the thoracic to lumbar type of articular surface has been believed to occur over 2 vertebral segments, but occurs over 3 segments in as many as 34% of the articular surfaces.     

New dysostosis showing multilevel absence of vertebral pedicles: Unique developmental anomaly of vertebral arches?

We report on an apparently normal child who shows hypopaplasia of the vertebral pedicles and posterior arches of several cervical, thoracic, and lumbar vertebrae with normally fused spinous apophyses, hypoplastic sacrum, lumbar epidural lipomatosis, synostoses of some cervical vertebral disks, and sacral spina bifida. The most likely mechanism is an abnormal differentiation of the spinal processes, due most probably to an absence of differentiation in cartilage of the dense mesenchyme forming their most anterior part. Because the anomalies affect multiple levels, we highly suspect a genetic basis to this unusual dysostosis affecting the development of the posterior sclerotomes. Am. J. Med. Genet. 95:473–476, 2000. © 2000 Wiley‐Liss, Inc.     

Vertebral spinal osteophytes

Osteoarthritis is a common complication in the elderly and is often associated with osteophyte growth on vertebral bodies. The clinical presentation of vertebral osteophytes is related to anatomical structures adjacent to the spinal column. For instance, cervical osteophytes potentially involve the pharynx and esophagus, leading to dysphagic symptoms that may be accompanied by food aspiration, vocal fold paralysis and obstructive sleep apnea. In addition to anterior cervical osteophytes, posterior and uncinate process osteophytes may form, compressing the spinal cord and vertebral artery blood supply, respectively. Cervical osteophytes have also been shown to form an accessory median atlanto-occipital joint when the relationship between the atlas, dens and basiocciput is involved. In the thorax, the esophagus is often affected by osteophytes and may result in dysphagia. Traumatic and non-traumatic thoracic aorta pseudoaneurysm formation has been attributed to sharp osteophytes lacerating the aorta, a direct complication of the relationship between the aorta anterior vertebral column. Additionally, aspiration pneumonia was reported in patients with compression of a main stem bronchus, due to mechanical compression by thoracic osteophytes. In the lumbar spinal region, the two major structures in close proximity to the spine are the inferior vena cava and abdominal aorta, both of which have been reported to be affected by osteophytes. Treatment of osteophytes is initially conservative with anti-inflammatory medications, followed by surgical removal. Increasing obesity and geriatric populations will continue to result in an array of osteoarthritic degenerative changes such as osteophyte formation.     

以椎板应力线及关节面为参考标志的改良椎弓根置钉方法的应用研究

目的　探讨确定脊柱经椎弓根置钉的改良方法。 方法　以椎板应力线及关节面为参考标志的改良置钉方法及传统置钉方法对205例脊柱疾患患者进行手术置钉, A组进钉点：按传统进钉方法。B组改良置钉方法：寻找椎板应力线骨嵴及关节面的位置,以此为参考点。应用术中及术后X线、CT检查及术中神经根剥离子触摸检查置钉准确性,计算术中一次性置钉的成功率,比较传统入钉法与改良入钉法的置钉成功率。 结果　应用传统置钉方法与改良置钉方法置钉成功率在颈椎手术中分别达到78.1%和95.5%（P＝0.002）,在胸椎手术中达到82.4%和95.9%（P<0.001）,在腰椎手术中达到80.3%和97.0%(P＜0.001）,总计成功率为80.7%和96.5%(P＜0.001）。两组差异有明显统计学意义。 结论　应用椎板应力线及关节面为参考标志的椎弓根置钉方法可以作为颈椎、胸椎及腰椎传统置钉方法的改良方法,有较高的置钉成功率。应力线骨嵴及关节面分别代表椎体的应力传导情况,按此参考标志进行置钉,可实现椎弓根置钉的个体化,有较大的应用价值。     

The vertebral level of origin of spinal nerves in the rat

Several dissections were performed to determine the level of spinal cord termination and the vertebral level at which the dorsal and ventral roots of spinal nerves C1-S4 emerged from the spinal cord in the rat. These levels of emergence were then compared to the level of exit from the vertebral canal. The dissections demonstrated that the effect of differential growth between spinal cord and vertebral column begins in the lower cervical region and becomes progressively more pronounced throughout thoracic and lumbar levels. The disparity between the vertebral level of emergence of spinal roots from the spinal cord and their level of exit via intervertebral foramina was found to be considerably larger than was previously reported by Greene ('68). It was further noted that the spinal cord terminated at the level of the intervertebral disc between the third and fourth lumbar vertebrae, not between the fourth and fifth lumbar vertebrae as reported by Greene ('68).     

Correlations between spondylometric features and body height of man

The author has studied correlational relationships of the spondylometric features on the material of 1,572 adult workers at Zabkowice 648 men and 924 women. He applied elastometric method in his own modification. Negative correlation between the length of thoracic kyphosis and the length of lumbar lordosis and the positive correlation between the length of the vertebral column and the body height have been stated. The findings confirm the results of previous studies in children and juveniles, and may be of value for the prevention of the diseases of the vertebral column.     

数字X线摄影组织均衡技术在胸腰段椎体病变的应用价值

目的探讨数字X线摄影（DR）组织均衡技术在胸腰段椎体病变诊断中的应用价值。方法80例骨折病人，其中男性66例，女性14例，年龄20～82岁，平均年龄52．5岁。用碘化铯非晶硅阵列数字平板探测器采集图像，行胸腰段椎体正侧位摄影，所有病人的侧位影像均行DR组织均衡技术后处理。由3位高级影像专家采用双盲法评价图像，并行统计学处理。结果胸腰段椎体病变32例，正常48例。胸腰段椎体侧位的常规DR与运用组织均衡技术处理的影像质量区别较大。差异有统计学意义。结论DR组织均衡技术对显示胸腰段椎体的侧位影像有较大的临床价值。     

Regional differences in zygapophysial joint cavities: A histological study of human fetuses

Human zygapophysial joints (ZJ) have regional differences in shape and orientation during prenatal growth. However, there is limited knowledge of the synovial recess during fetal development. We examined sagittal and horizontal histological sections of the vertebral columns of 30 human fetuses at gestational ages of 8–37 weeks. Fetuses of all gestational ages had subaxial cervical articular processes that were thicker than in the thoracolumbar regions, and as large as the corresponding vertebral bodies. A small or large synovial recess extending beyond the articular cartilage was evident at most regions. The cervical ZJ had large or deep recesses that extended inferiorly in midterm fetuses and posteromedially along the vertebral pedicle and lamina in near-term fetuses. Likewise, the thoracic ZJ had small recesses that extended superiorly in midterm fetuses and medially in near-term fetuses. The lumbar recesses extended laterally beyond the medially shifted articular cartilage of the upper adjacent vertebrae in near-term fetuses and the lumbar articular surface was smallest in the three regions at all stages. At any region, a deep recess appeared before an area expansion of the ZJ cartilage. A drastic change in direction and size of the prenatal recess seemed to occur depending on a possible minute dislocation of the ZJ. In particular, a deep posteromedial recess of the cervical ZJ, which extended far beyond the articular cartilage, might be necessary to maintain high flexibility suitable for the strong flexion posture in utero.     

椎管与内容物相互关系的研究

用30条已防腐的成人脊柱,从椎间盘处横锯,测量了各段椎管与内容物的矢径。椎管内硬膜前组织较薄,一般不超过2.0mm,硬膜后组织,由上向下逐渐变厚。椎管与硬膜囊的比值(矢状径)颈段为1:0.73,胸段1:0.68,腰段为1:0.60。从本组材料看,C_(3-5)椎骨段有50％以上椎管矢径较细窄,蛛网膜下腔亦较窄,故受压后缓冲余地小,易出现症状。腰段由上向下硬膜囊的逐渐变小,周围组织逐渐增多,故不易受压。     

How the even-toed ungulate vertebral column works: Comparison of intervertebral mobility in 33 genera

In this study, we used a previously developed osteometry-based method to calculate available range of motion in presacral intervertebral joints in artiodactyls. We have quantified all three directions of intervertebral mobility: sagittal bending (SB), lateral bending (LB), and axial rotation (AR). This research covers 10 extant families of artiodactyls from 33 genera and 39 species. The cervical region in artiodactyls is the most mobile region of the presacral vertebral column in SB and LB. Mobility is unevenly distributed throughout the joints of the neck. The posterior neck joints (C4–C7) are significantly more mobile (on average by 2.5–3.5°) to anterior joints (C2–C4) and to the neck–thorax joint (C7–T1) in SB and LB. An increase in the relative length of the cervical region in artiodactyls is accompanied by an increase in the bending amplitudes (SB: Pearson r = 0.781; LB: r = 0.884). Animals with the most mobile necks (representative of Giraffidae and Camelidae) are 2–3 times more mobile in SB and LB compared to species with the least mobile necks. The thoracic region in artiodactyls, as in other mammals, is characterized by the greatest amplitudes of AR due to the tangential orientation of the zygapophyseal articular facets. The lowest AR values in the thoracic region are typical for the heaviest artiodactyls—Hippopotamidae. The highest AR values are typical for such agile runners as cervids, musk deer, pronghorn, as well as large and small antelopes. SB mobility in the posterior part of the thoracic region can be used by artiodactyls during galloping. The highest values of SB aROM in the posterior part of the thoracic region are typical for small animals with high SB mobility in the lumbar region. The lumbar region in mammals is adapted for efficient SB. Both the cumulative and average SB values in the lumbar region showed correspondence to the running type employed by an artiodactyl. The greatest SB amplitudes in the lumbar region are typical for small animals, which use saltatorial and saltatorial–cursorial running. An increase in body size also corresponds to a decrease in lumbar SB amplitudes. The lowest SB amplitudes are typical for species using the so-called mediportal running. Adaptation to endurance galloping in open landscapes is accompanied by a decrease in lumbar SB amplitudes in artiodactyls. The consistency of the approach used and the wide coverage of the studied species make it possible to significantly expand and generalize the knowledge of the biomechanics of the vertebral column in artiodactyls.     

Vertebral pattern variation in the North Sea harbor porpoise (Phocoena phocoena) by computed tomography

Vertebral series in the harbor porpoise (Phocoena phocoena) include cervical, thoracic, lumbar, and caudal. In contrast to studying skeletons from museums, in which small bones can be missed, evaluation of full body computed tomography (CT) scans provides an overview of the vertebral column, while maintaining interrelationship of all structures. The aim of this study was to document variations in vertebral patterning of the harbor porpoise via evaluation of CT images of intact stranded harbor porpoises. The harbor porpoises were divided into age classes, based on developmental stage of reproductive organs on postmortem examination and closure of proximal humeral physis on CT. Numbers of vertebrae per series, fusion state of the syncervical, type of first hemal arch, number of double articulating ribs, and floating ribs were recorded based on CT images. Included in the study were 48 harbor porpoises (27 males and 21 females), which were divided in two age classes (27 immatures and 21 adults). Total vertebral count varied from 63 to 68 with vertebral formula range C7T12-14L12-16Cd29-33. Twenty-five different vertebral formulas were found, of which C7T13L14Ca30 was the most common (n = 8, 17%). Thoracic vertebrae with six, seven, or eight double articulating ribs and zero, one, or two vertebrae with floating ribs were seen. Four different fusion states of the syncervical and four types of hemal arches were recognized. This study showed a great variation in vertebral patterning in the harbor porpoise, with homeotic and meristic variation in the thoracic, lumbar, and caudal vertebral series.     

经皮穿刺椎体后凸成形中骨水泥渗漏入椎管与胸腰椎椎体后壁形态的关系

背景:经皮穿刺椎体后凸成形术(percutaneous kyphoplasty,PKP)是治疗骨质疏松性椎体压缩骨折的有效方法,虽然临床效果满意,但骨水泥渗漏仍然为其主要并发症,既往文献报道骨水泥渗漏进入椎管的因素较多,但由于缺少对于胸、腰椎椎体后壁形态的观察,胸腰椎椎体后壁形态差异可能也是导致骨水泥渗漏进入椎管的重要因素之一。目的:探讨胸、腰椎椎体后壁形态对骨质疏松性椎体压缩骨折患者行PKP术骨水泥渗漏入椎管的影响。方法:选取行PKP术治疗的临床资料完整并同时具有T6-L5的CT平扫及三维重建影像资料的骨质疏松性椎体压缩骨折患者98例。采用CT三维重建及多平面重建技术测量非骨折椎体后壁凹入椎体的深度及相应椎体中矢状径,计算各椎体后壁凹入椎体深度占同一椎体中矢状径百分比。将测量椎体分为胸椎组(T6-T12)和腰椎组(L1-L5)进行比较观察。选择同期内行PKP手术治疗无CT三维重建资料的骨质疏松性椎体压缩骨折患者357例(548个椎体),也分为胸椎组和腰椎组观察比较骨水泥渗漏侵占椎管程度。结果与结论:①测量98例患者椎体后壁参数发现,椎体后壁凹入椎体深度在T6-T12逐渐加深,平均4.6 mm;L1-L5逐渐变浅,平均0.6mm,椎体后壁凹入椎体深度占同一椎体中矢状径百分比T6-T12均为16%(1/6);L1-L5平均为3%,腰椎较胸椎明显小于16%(1/6);②观察同期行PKP手术治疗的357例患者发现:胸椎行PKP术骨水泥脉渗漏入椎管渗漏率为10.2%(31/304),腰椎渗漏率为3.7%(9/244)。胸椎组骨水泥渗漏侵占椎管最大矢状径平均为(3.1±0.2)mm,侵占椎管面积平均为(30.8±0.3)mm2,椎管侵占率为(22.5±0.2)%;腰椎组骨水泥渗漏侵占椎管最大矢状径为(1.4±0.1)mm,侵占椎管面积为(14.9±0.2)mm2,椎管侵占率为(11.4±0.3)%,胸椎组骨水泥渗漏发生率、侵占椎管最大矢状径、面积明显大于腰椎组(P<0.05)。③结果证实,中下胸椎行PKP术应尽量避免骨水泥分布达到椎体后16%(1/6),因中下胸椎、腰椎椎体后壁凹入椎体深度差异会对PKP术骨水泥渗漏进入椎管的观察造成影响,可能是导致中下胸椎椎管内骨水泥渗漏率明显高于腰椎的原因之一。该试验获得西南医科大学附属医院伦理委员会批准(批准号:K2018008)。