Precision measurement of segmental motion from flexion-extension radiographs of the lumbar spine

OBJECTIVE: To measure sagittal plane motion of lumbar vertebrae from lateral radiographic views. Previously identified factors of imprecision such as distortion in central projection, off-centre position, axial rotation, and lateral tilt of the spine were compensated. STUDY DESIGN: This study presents a new protocol to measure sagittal plane rotational and translational motion from lateral flexion-extension radiographs of the lumbar spine. BACKGROUND: Conventional methods to determine sagittal plane rotation and translation are prone to error from the distortional effects of the divergence of the radiographic beam and the measurement error inherent in constructing tangents to the contours of the vertebral body. High precision is attained by roentgen-stereophotogrammetric methods, but because of their invasive nature they can be applied only in exceptional cases. Agreement has been reached only in that measurement of sagittal plane motion from lumbar spine flexion-extension radiographs is inaccurate. Normal patterns of sagittal plane motion and the definition of what is an abnormal flexion-extension radiograph have not been settled. METHOD: Starting from an analysis of vertebral contours in the lateral view, geometric measures are identified which are virtually independent of distortion, axial rotation or lateral tilt. Applying a new protocol based on those geometric measures, the pattern of translational and rotational motion was determined from flexion-extension radiographs of 61 symptom-free, adult subjects. Measurement errors were quantified in a specimen experiment; a reproducibility study quantified inter- and intraobserver errors. RESULTS: Magnitude and sign of 'translation per degree of rotation' determined from a cohort of 61 adult subjects were very uniform for all levels of the lumbar spine. An auxiliary study evaluating a cohort of 10 healthy subjects where flexion-extension radiographs had been taken standing and side-lying showed no dependence of the rotation/translation pattern on posture. The error study demonstrated errors in angle ranging between 0.7 and 1.6 degrees and errors in displacement ranging between 1.2% and 2.4% of vertebral depth (the largest errors occurring at the L(5)/S(1) segment). Intra- and interobserver tests showed no or only negligibly small bias and an SD virtually equal to the measurement error multiplied by radical2. The relation of displacement to angle observed in the normal cohort can be used in individual cases to predict translational motion depending on the rotation actually performed. A comparison of the predicted translation (determined from normal controls) and the value actually measured allows translational hypo-, normal, or hypermobility to be quantified. Examples illustrate application of the new method in cases of normal, hypo-, and hypermobility and in the case of an instrumented spine. CONCLUSIONS: The results of this study show that precision of the measurement of rotational and translational motion can be considerably enhanced by making allowance for radiographic distortional effects and by minimizing subjective influence in the measurement procedure.     

Congenital cervical block vertebrae are associated with caudally adjacent discs

BACKGROUND: Knowledge on the time course of changes in cervical disc height and cervical kinematics at motion segments adjacent to congenital block vertebrae is fragmentary. Compared with this, after surgical fusion of cervical spine segments some find increased degenerative processes in combination with hypermobility or instability while others were unable to confirm these changes. This cross sectional study was undertaken to investigate whether congenital block vertebrae are associated with an increased risk of disc degeneration and hypermobility at adjacent motion segments. METHODS: In 25 subjects (mean age 40 years) disc height, vertebral height and segmental mobility at motion segments adjacent to a congenital block vertebra were assessed quantitatively by distortion-compensated Roentgen analysis. The findings were compared to a normal database. FINDINGS: Height of the disc cranially adjacent to the block vertebra did not deviate from the norm while height of the caudally adjacent disc was significantly reduced. The height of the vertebrae adjacent to the block did not deviate from normal. The motion segments formed by the block vertebra and the adjacent discs and vertebrae exhibited no deviation from normal with respect to sagittal plane rotational or translational motion. INTERPRETATION: Congenital block vertebrae do not result in rotational or translational hyper- or hypomobility at motion segments adjacent to the block. Whether the observed, significant height reduction of the caudally adjacent disc is caused by degeneration following the block formation cannot undoubtedly be concluded as the initial state is not known. Further longitudinal studies are needed to investigate this issue.     

Comparison of dynamic posteroanterior spinal stiffness to plain film radiographic images of lumbar disk height

BACKGROUND: Assessments of spinal stiffness have become more popular in recent years as a noninvasive objective biomechanical means to evaluate the human spine. Studies investigating posteroanterior (PA) forces in spinal stiffness assessment have shown relationships to spinal level, body type, and lumbar extensor muscle activity. Such measures may be important determinants to discriminate between patients with low back pain (LBP) and asymptomatic subjects. OBJECTIVE: To determine the relationships between dynamic PA spinal stiffness and radiographic measures of lower lumbar disk height and disk degeneration. METHODS: L4 and L5 posterior disk height (PDH), vertebral body height (PVH), anterior disk height (ADH), and vertebral body height (AVH) were obtained from digitized plain film anteroposterior (AP) and lateral radiographs of 18 symptomatic LBP patients presenting to a chiropractic office (8 female patients and 10 male patients, aged 15-69 years, mean 44.3, SD 15.4 years). Disk degeneration (DD) and facet arthrosis (FA) were qualitatively assessed from the films by an independent examiner. Anterior disk height ratios (ADHR = ADH/AVH) and posterior disk height ratios (PDHR = PDH/PVH) were calculated from the disk height measurements and were compared to L4 and L5 posteroanterior spinal stiffness obtained using a previously validated mechanical impedance stiffness assessment procedure. RESULTS: One third of the subjects were found to have radiographic evidence of mild or moderate DD and approximately two thirds of the subjects showed signs of mild or moderate FA. The L4 and L5 anterior disk height and posterior disk height were approximately one half and one fifth of the respective vertebral body heights, and the PA stiffness was greater at L4 than at L5. Male subjects had a greater ADHR than female subjects, but female subjects had a greater L4 and L5 PA stiffness in comparison to male subjects; however, these differences were not statistically significant. Posteroanterior L5 vertebral stiffness was found to be significantly correlated to the L5 PDHR. CONCLUSIONS: Computations of spinal input impedance are relatively simple to perform, can provide a noninvasive measure of the dynamic mechanical behavior of the spine, appear to have potential to discriminate pathologic changes to the spine, and warrant further study on a larger sample of normal subjects and patients.     

Cervical zygapophyseal joints: geometrical parameters and relationship to cervical kinematics

The relationship was examined between the height and slope of the cervical zygapophyseal joints and the patterns of motion of the cervical vertebrae. The height and orientation of the C₃---C₇ superior articular processes were measured in lateral radiographs of 40 normal subjects. The C₄-C₆ facets were oriented at approximately 40° to the vertical, while the C₃ and C₇ facets were more steeply oriented. The heights of the superior articular processes were found to increase at progressively lower vertebral levels. Contrary to published views, the slope of the superior articular facets has no bearing on the pattern of motion of the cervical vertebrae. No relationship was found between slope of the facets and the location of the instantaneous axes of rotation of the cervical vertebrae. In contrast the height of the articular processes was perfectly related to the location of the axes of rotation. Articular height, but not slope, is a major determinant of the patterns of motions of the cervical vertebrae.

This study provides data necessary to confirm or deny the putative roles of the cervical zygapophyseal joints in determining motion of the cervical spine in the sagittal plane.     

Unsuspected upper cervical spine fractures associated with significant head trauma: role of CT

Several recent studies report the sensitivity of computed tomography (CT) to be far greater than that of traditional plain film radiographic studies for evaluation of cervical spine fractures and spinal cord pathology. Nevertheless, plain films continue to be the standard screening examination. CT is used only if fractures are demonstrated or suspected on plain film survey. Recently, three patients with significant head and neck trauma (all three patients had intracranial hemorrhage) had cervical spine evaluation by computed tomography and standard plain film views. CT demonstrated significant C1-C2 fractures, while plain films were completely normal in all three cases. Prospectively studying the next 50 patients with significant head trauma, we added a few more slices to the routine head scan protocol to cover the first three cervical vertebrae. This added very little time or cost to the procedure. The additional CT images demonstrated four upper cervical fractures that could not be seen on plain films, even in retrospect. Our findings suggest that routine inclusion of the upper cervical spine with head CT is appropriate in the evaluation of patients with significant head trauma as defined by intracranial hemorrhage or skull fracture.     

Evaluation of axial and flexural stresses in the vertebral body cortex and trabecular bone in lordosis and two sagittal cervical translation configurations with an elliptical shell model

BACKGROUND: Osteoarthritis and spinal degeneration are factors in neck and back pain. Calculations of stress in clinically occurring configurations of the sagittal cervical spine are rare. OBJECTIVE: To calculate and compare combined axial and flexural stresses in lordosis versus cervical configurations in anterior and vertical sagittal head translated positions. DESIGN: Digitized measurements from lateral cervical radiographs of 3 different shapes were used to calculate axial loads and bending moments on the vertebral bodies of C2-C7. METHODS: An elliptical shell model was used to model horizontal cross-sections of the vertebral bodies of C2 through T1. Axial and flexural stresses were calculated with short compression block equations. Elliptical shell modeling permitted separation of stresses into cortical and inner medullary regions. Digitized radiographic points were used to create polynomials representing the shape of the sagittal cervical curvatures from C1 to T1. To calculate bending moments at each vertebral segment, moment arms from a vertical line through C1 were determined from digitizing. RESULTS: Compared with the normal lordosis, stresses on the anterior vertebral body cortical margins of C5-T1 in the sagittal translated postures are compression rather than tension. At the posterior vertebral bodies in the anteriorly translated position and vertically translated postures, the stresses change from compression to tension at C5 through T1. In absolute value (ABS) compared with values at the same segments in a normal lordosis, the magnitude of the combined anterior stresses in the sagittal postures are higher at C5-C7 (eg, ABS[sigma(straight)/sigma(normal)] approximately 1.25 to 4.25). CONCLUSIONS: Vertebral body stresses are reversed in direction at C5-T1 in sagittal translated postures compared to a normal lordosis. Stress analysis, with implications for bone remodeling, indicates that both sagittal head translation postures, anterior head carriage, and vertical head translation, are undesirable configurations in the cervical spine.     

睡姿和枕高对颈椎应力影响的三维有限元分析

背景:目前睡姿和枕高的研究主要集中在临床方面,多采用统计调查、测量及影像学相结合的方法。但采用三维有限元法分析睡姿和枕高对颈椎应力影响的研究至今鲜见报道。目的:采用数学仿真的方法探讨睡姿及枕高对颈椎应力的影响。方法:以正常人体头颈CT图像为原始数据,依次经过Mimics 10.0、Geomagic Studio 11.0及Hypermesh 10.0软件建立全颈椎的三维有限元模型,利用Abaqus 6.10软件仿真分析仰卧状态与侧卧状态不同枕高下颈椎的应力特性。结果与结论:睡姿和枕高对颈椎应力均有影响。枕高相同时,仰卧位椎间盘应力的最大值大于侧卧位。同样睡姿下,颈椎椎体及椎间盘的应力值均随枕高的增加而增大。从颈椎应力的生物力学角度看,侧卧比仰卧更有利于颈椎的健康,且仰卧位枕高应低于侧卧位。     

胸骨柄松质骨结合钛网支撑满足颈椎前路修复植骨需求的可行性

背景:现今临床上常用的自体植骨材料多为髂骨、胫骨、腓骨等部位的松质骨块或骨碎块.采用胸骨柄松质骨作为植骨材料融合稳定颈椎未见报道.目的:测量国人胸骨柄标本及无明显退变的颈椎X射线侧位片,探讨胸骨柄内松质骨结合钛网植骨在颈椎前路手术中应用的可行性,为自体骨移植开发一个新的植骨材料来源.方法:测量40具胸骨柄标本的胸骨柄长、胸骨柄最大宽、胸骨柄最小宽、胸骨柄厚、胸骨柄前皮质厚及胸骨柄后皮质厚,计算胸骨柄体积.将胸骨柄长、胸骨柄最大宽、最小宽每边减去4 mm,胸骨柄前、后皮质骨减去1 mm作为胸骨柄内松质骨取骨区(以下简称供区)边界,计算胸骨柄内供区的体积.选择106例无明显退变的中立位颈椎侧位X射线片,测量C2～3至C7～T1椎间隙和C3～C7椎体高度.计算常规颈椎前路术中单间隙、双间隙、三间隙椎间盘切除,1个椎体+2个椎间盘及2个椎体+3个椎间盘切除所需钛网长度和钛网内所需植骨体积.验证供区内松质骨是否满足临床需要.结果与结论:胸骨柄体积为(17 735.51± 5 231.93) mm3;供区松质骨体积为(8 982.83± 2 437.56) mm3.颈前路术中使用钛网最短和所需植骨量最小为单间隙植骨,所需钛网最长和所需植骨量最大为2个椎体+3个椎间隙切除.颈椎前路常用的任意一种术式中,钛网内所需盛骨体积均明显小于供区体积.提示胸骨柄内松质骨结合钛网支撑可满足大多数颈椎前路融合过程中的植骨需求.与自体髂骨植骨相比,操作更简单方便,不影响患者早期功能锻炼和负重行走.

Abstract：

BACKGROUND: Current commonly used bone graft materials include cancellous bone or bone blocks from ilium, tibia, fibula and others. There is no report of bone graft and fusion in cervical spine from manubrium sterni. OBJECTIVE: To measure lateral X-ray of cervical vertebrae with no degeneration and manubrium sterni samples to explore feasibility of autologous cancellous bone graft of manubrium sterni with pyramesh in anterior cervical spinal fusion surgery, so as to develop a new source of autogenous bone graft.METHODS: A total of 40 manubrium sterni specimens were selected and the length, maximum width and minimum width, thickness, anterior and posterior cortex thickness of manubrium sterni were measured. Manubrium sterni area was calculated: the length, maximum width and minimum width were 4 mm reduced from those of manubrium sterni, its thickness was 2 mm reduced from that of manubrium sterni. The formula of measuring the manubrium sterni volume is (maximum width of manubrium sterni + the minimum width of manubrium sterni)×length of manubrium sterni × thickness of manubrium sterni×1/2. Intervertebral height and vertebral height from C2 to C7 were measured from lateral cervical radiograph of 106 patients with cervical radiolopathy, and the length of pyramesh needed in anterior cervical spinal surgery for one, two, three discs resection, one vertebra plus two discs resection and two vertebrae plus three discs resection was calculated. RESULTS AND CONCLUSION: The manubrium sterni volume was (17 735.51±5 234.92) mm3 and the volume of bone-grafting area was (8 982.83±2 427.76) mm3. The length of pyramesh and volume of bone used in operation were minimal for one disc resection, and maximal for two vertebrae plus three discs resection. The volume of bone graft in the pyramesh was significantly less than the donor area in any anterior cervical spinal fusion operation. Results show that autologous cancellous graft of manubrium sterni combined with pyramesh supporting can be used in anterior cervical spinal fusion surgery. Compared with autologous iliac graft, this method is simpler and does not influence early functional exercise or walking bearing weight.     

Line drawing analyses of static cervical X ray used in chiropractic.

OBJECTIVE: This review article identifies the chiropractic techniques used to assess the structure of the cervical spine as seen on the static cervical radiograph. DATA SOURCES: On-line search of MEDLINE, key words, radiograph and X ray in combination with cervical spine (vertebrae); the Chiropractic Research Archives Collection (CRAC); indexes published in the Journal of Chiropractic Research; conference proceedings from Annual Biomechanics Conference of the Spine, FCER sponsored conferences and Annual Upper Cervical Spine Conference; references identified from bibliographies of pertinent articles; a telephone poll of radiography/technique instructors at chiropractic colleges. STUDY SELECTION: Techniques that quantitatively assess relative alignment of skeletal structures or distortion of the spinal column. DATA EXTRACTION: Techniques were grouped according to the structures analyzed and the views used. DATA SYNTHESIS: Variables and artifacts that limit the reliability or validity of static cervical X ray line drawing analysis were identified and the techniques assessed for their reported reliability and validity. CONCLUSIONS: Reliability studies exist showing that inter- and intraexaminer reliability are sufficient to measure lateral and rotational displacements of C1 to within +/- 1 degree. This amount of error allows objective analysis of upper cervical X rays to detect changes in the angular positional relationships of radiographic images on the order of those already seen clinically. Methods of cervical analysis that use relative angular measures of skeletal positioning are best able to control the effects of radiographic distortion. The accuracy of the analysis methods has not been ascertained to establish the extent to which angular measurement of vertebral relationships actually reflect three-dimensional movement. It is not known how much of the changes that are seen in pre/post-radiograph sets are due to positioning changes of the patient between radiographic procedure, and how much are due to actual changes of skeletal relationships brought about by adjustment.     

Comparison of axial and flexural stresses in lordosis and three buckled configurations of the cervical spine

OBJECTIVE: To calculate and compare combined axial and flexural stresses in lordosis versus buckled configurations of the sagittal cervical curve. DESIGN: Digitized measurements from lateral cervical radiographs of four different shapes were used to calculate axial loads and bending moments on the vertebral bodies of C2-C7.Background. Osteoarthritis and spinal degeneration are factors in neck and back pain. Calculations of stress in clinically occurring configurations of the sagittal cervical spine are rare. METHODS: Center of gravity of the head (inferior-posterior sella turcica) and vertebral body margins were digitized on four different lateral cervical radiographs: lordosis, kyphosis, and two "S"-shapes. Polynomials (seventh degree) and stress concentrations on the concave and convex margins were derived for the shape of the sagittal cervical curvatures from C1 to T1. Moments of inertia were determined from digitizing and the use of an elliptical shell model of cross-section. Moment arms from a vertical line through the center of gravity of the head to the atlas and scaled neck extensor moment arms from the literature were used to compute the vertical component of extensor muscle effort. Segmental lever arms were calculated from a vertical line through C1 to each vertebra. RESULTS: In lordosis, anterior and posterior stresses in the vertebral body are nearly uniform and minimal. In kyphotic areas, combined stresses changed from tension to compression at the anterior vertebral margins and were very large (6-10 times as large in magnitude) compared to lordosis. In kyphotic areas at the posterior vertebral body, the combined stresses changed from compression (in lordosis) to tension. CONCLUSIONS: The stresses in kyphotic areas are very large and opposite in direction compared to a normal lordosis. This analysis provides the basis for the formation of osteophytes (Wolff's Law) on the anterior margins of vertebrae in kyphotic regions of the sagittal cervical curve. This indicates that any kyphosis is an undesirable configuration in the cervical spine. Relevance. Osteophytes and osteoarthritis are found at areas of altered stress and strain. Axial and flexural stresses at kyphotic areas in the sagittal cervical spine are abnormally high.     

Clinical and radiological evaluation of Vertebrace extrication collars

An aid for prehospital cervical immobilization was studied radiographically. We applied the Vertebrace Extrication Collar to ten volunteers and measured cervical movement in the sagittal plane. Results of mean degrees of flexion-extension and mean percentage of restricted motion at each level compared favorably with results of earlier studies using rigid orthoses (the four-poster brace, Cervicothoracic, Somi Brace, and Yale collar). A second method of analysis, measuring relative motion of vertebral segments by level, found no flexion displacement in 70% and no extension displacement in 60% at C5-C6. The Vertebrace Collar proved to be effective in restricting movement of the cervical vertebrae most often injured following serious trauma.     

胸骨柄松质骨结合钛网支撑满足颈椎前路修复植骨需求的可行性

背景：现今临床上常用的自体植骨材料多为髂骨、胫骨、腓骨等部位的松质骨块或骨碎块。采用胸骨柄松质骨作为植骨材料融合稳定颈椎未见报道。目的：测量国人胸骨柄标本及无明显退变的颈椎X射线侧位片,探讨胸骨柄内松质骨结合钛网植骨在颈椎前路手术中应用的可行性,为自体骨移植开发一个新的植骨材料来源。方法：测量40具胸骨柄标本的胸骨柄长、胸骨柄最大宽、胸骨柄最小宽、胸骨柄厚、胸骨柄前皮质厚及胸骨柄后皮质厚,计算胸骨柄体积。将胸骨柄长、胸骨柄最大宽、最小宽每边减去4mm,胸骨柄前、后皮质骨减去1mm作为胸骨柄内松质骨取骨区（以下简称供区）边界,计算胸骨柄内供区的体积。选择106例无明显退变的中立位颈椎侧位X射线片,测量C2～3至C7～T1椎间隙和C3～C7椎体高度。计算常规颈椎前路术中单间隙、双间隙、三间隙椎间盘切除,1个椎体＋2个椎间盘及2个椎体＋3个椎间盘切除所需钛网长度和钛网内所需植骨体积。验证供区内松质骨是否满足临床需要。结果与结论：胸骨柄体积为（17735.51±5231.93）mm3;供区松质骨体积为（8982.83±2437.56）mm3。颈前路术中使用钛网最短和所需植骨量最小为单间隙植骨,所需钛网最长和所需植骨量最大为2个椎体＋3个椎间隙切除。颈椎前路常用的任意一种术式中,钛网内所需盛骨体积均明显小于供区体积。提示胸骨柄内松质骨结合钛网支撑可满足大多数颈椎前路融合过程中的植骨需求。与自体髂骨植骨相比,操作更简单方便,不影响患者早期功能锻炼和负重行走。     

Finite element analysis of the cervical spine: a material property sensitivity study

OBJECTIVE: The study determined the effect of variations in the material properties of the cervical spinal components on the output of the finite element analysis (external and internal responses of the cervical spine) under physiologic load vectors. DESIGN: A three-dimensional (3D) anatomically accurate finite element model comprising of the C4-C5-C6 cervical spine unit including the three vertebrae, two interconnecting intervertebral discs, and the anterior and posterior ligament complex is used. BACKGROUND: The effect of material property variations of spinal components on the human lumbar spine biomechanics is extensively studied. However, a similar investigation of the cervical spine is lacking. METHODS: Parametric studies on the variations in the material properties of all the cervical spine components including the cortical shell, cancellous core, endplates, intervertebral disc, posterior elements and ligaments were conducted by exercising the 3D finite element model under flexion, extension, lateral bending and axial torsion loading modes. Low, basic and high material property cases for each of the six components under all the four physiologic loading modes were considered in the finite element analysis. A total of 432 results were evaluated to analyze the external angular rotation, and the internal stresses in the middle vertebral body, the superior and inferior endplates and the two intervertebral discs. RESULTS: Variations in the material properties of the different cervical spinal components produced dissimilar changes in the external and internal responses. Variations in the material properties of the cancellous core, cortical shell, endplates and posterior element structures representing the hard tissues did not affect the external angular motion, and the internal stresses of the inferior and superior intervertebral discs under all four loading modes. In contrast, variations in the material properties of the intervertebral disc and ligament structures representing the soft tissues significantly altered the angular motion, and the stresses in the inferior and superior intervertebral discs of the cervical spine. CONCLUSION: The material properties of the soft tissue structures have a preponderant effect on the external and internal responses of the cervical spine compared with the changes in the material properties of the hard tissue structures. RELEVANCE: Bone remodeling (e.g., osteophyte) secondary to degeneration of the human cervical joints may be explained by a change in the material property of the soft tissues, coupled with an increase in stress (due to these material property variations) in the spinal components. Consequently, to accurately predict the biomedical effects of cervical spine degeneration, it is critical to accurately determine the material property of these components.     

羟基磷灰石/聚酰胺66颈椎融合器在颈椎间盘突出症前路手术重建中的临床疗效

目的探讨纳米羟基磷灰石/聚酰胺66（nano-hydroxyapatite polyamide66,n-HA/PA66）颈椎融合器在颈椎间盘突出症前路手术重建中的临床疗效。方法 2008年12月-2010年6月,对14例颈椎间盘突出症患者行前路椎间盘切除、椎管减压,以n-HA/PA66椎间融合器支撑植骨、钢板螺钉内固定治疗。随访时间3～12个月,平均6.3个月;随访时以日本矫形外科学会（Japan Orthopaedic Assoctiation,JOA）评分改善率评价患者神经功能恢复情况,复查X线片评估椎间融合器植骨融合情况,包括椎间高度及椎间融合器下沉情况。结果 14例患者均成功完成颈椎前路减压手术以及椎间融合器的安放固定。所有患者术前症状均得到不同程度的改善,术后3、6、12个月的JOA改善率分别为87.0%、94.0%、97.0%。影像学检查显示所有患者植骨融合,椎间高度及椎间融合器的位置维持良好,无下沉、移位。结论 n-HA/PA66颈椎间融合器具有早期支撑稳定功能,可有效维持颈椎椎间高度;术后植骨融合率高且便于X线片观察,是颈椎间盘突出症患者前路手术植骨的理想支撑材料,但长期效果需进一步随访观察。     

Cervical spine imaging in trauma patients: a simple scheme of rationalising arm traction using zonal divisions of the vertebral bodies.

OBJECTIVE--To evaluate the effectiveness of arm traction for cervical spine imaging in trauma patients and devise a scheme to predict the probability of visualising the C7/T1 level in trauma patients. METHODS--98 trauma patients were studied. Each vertebral body was divided into three equal horizontal zones, the disc space between vertebral bodies being equivalent to one zone. The fifth cervical vertebra was used as the starting level (zone 1). Zones obtained pre and post arm traction on the lateral cervical spine radiographs were recorded. Results were analysed to show the probability of imaging the lower cervical spine, including the cervico-thoracic junction. RESULTS--If the initial film showed less than zone 10 (mid-C7 vertebra), the probability of showing zone 13 (upper body of T1) with arm traction was only 7.7%, that is, one success in every 13 pulls; or conversely, 12 failures in every 13 pulls. CONCLUSIONS--Unless an initial cervical spine radiograph includes the upper one third of the body of the C7 vertebra, the probability of attaining the C7/T1 level with arm traction is < 15%. It is suggested that all initial radiographs of the lateral cervical spine in major trauma patients be done with arm traction, and where the upper one third of the body of C7 vertebra is not seen, then computerised tomography, swimmer's, or oblique views be considered.     

颈性眩晕患者的寰枢椎影像学特征

目的探讨颈性眩晕患者的寰枢椎影像学特征。方法对74例颈性眩晕患者摄颈椎前后位、侧位及颈椎张口位片，部分患者行寰枢椎CT三维重建和／或颈椎MRI椎动脉造影。结果本组患者的影像学异常主要有颈椎生理曲度变直、寰椎两侧块宽度不等或／和两侧块与枢椎齿状突间距离不等、侧块下关节面与枢椎上关节面不平行等；寰枢椎CT三维重建可显示寰椎侧移和旋转；颈椎MRI椎动脉造影可显示寰椎侧移和旋转对椎动脉的影响；寰椎后弓以上旋转和侧移的椎动脉商径变小。结论颈性眩晕的病变部位主要在寰枢椎，发病机制是寰椎侧移和向前或后旋转。     

C4～C6颈椎有限元模型的建立和多点力学加载方法

背景:人体颈椎运动是多节段之间相互力学及位移关系的变化,建立多节段有限元模型及多点力学加载方法可以为颈椎生物力学研究提供高精度的模型和科学的计算分析方法。目的:建立人体C4~C6颈椎三维有限元模型,并在此基础上提出多点力学加载方法。方法:以正常人C4~C6颈椎CT图像作为数据源,利用Mimics10.0、Ansys11.0有限元分析软件建立三维有限元模型,对其进行多点力学加载测试,模拟生理状态时颈椎的轴向、屈曲、后伸、侧弯、扭转运动,分析各运动状态下C4~C6颈椎关节突和椎间盘的应力和位移改变。结果与结论:建立的C4~C6颈椎有限元模型几何形态逼真,重现了C4~C6颈椎节段解剖结构外形,整体显示直观,表面无过多简化,建成后的三维有限元模型与实体组织具有良好的几何相似性。应力Se、Sz在不同加载工况时,前屈/后伸>侧弯>轴向加载。轴向加载载荷明显小,导致应力位移水平低。提示应用正常人体原始资料构建的C4~C6颈椎有限元模型以及多点力学加载分析的方法科学有效,为颈椎的生物力学研究提供了高精度模型和科学的计算分析方法。     

不同时期颈椎病患者颈椎骨密度变化与椎体变形关系

目的:通过对颈椎病患者X线和颈椎骨密度的测量,探讨不同年龄段颈椎病患者颈椎椎体变形与骨密度变化之间的关系。方法:分3组,正常组20例,平均年龄23岁;颈椎间盘突出症组(颈椎组)22例,平均年龄43岁,腰椎骨密度正常;骨质疏松合并颈椎管狭窄症组(疏松组)28例,平均年龄58岁,腰椎骨密度显示骨质疏松。所有病例测量颈椎侧位C3～C6的椎管、椎体矢状径比,椎体变形指数,C4～C6骨密度。数据进行统计学处理。结果:与正常组相比,颈椎组患者仅在C5,C6椎体出现轻度椎管狭窄,椎体变形,骨密度无明显变化;疏松组则是颈椎高度减低,周径增宽,骨密度升高,3值之间有明显的相关性。结论:椎体骨质疏松的发展与颈椎病的自然发展病程具有明确的相关性,可能是颈椎开始退变进而发展为颈椎病的始动因素之一。     

Distracting injuries in patients with vertebral injuries

To describe the prevalence and types of distracting injuries associated with vertebral injuries at all levels of the spine in blunt trauma patients. A prospective cohort study was conducted at an urban Level I trauma center. All patients undergoing radiographic evaluation of the cervical, thoracic, or lumbar vertebrae after blunt trauma were enrolled. Patients had a data collection form completed by the treating physician before radiographic imaging and were evaluated for the following upon initial presentation: tenderness to the cervical, thoracic, or lumbar spine, distracting injuries, altered mental status, alcohol or drug intoxication, or neurological deficits. Patients with distracting injuries as the sole documented indication for vertebral radiographs were reviewed for the types of injuries present. A total of 4698 patients were enrolled in the study. There were 336 (7.2%) patients who had distracting injuries as the sole documented indication for obtaining radiographic studies of the vertebrae. Eight (2.4%, 95% CI 1.0-4.6%) of the 336 patients had 14 acute vertebral injuries including compression fractures (5), transverse process fractures (7), spinous process fracture (1), and cervical spine rotatory subluxation (1). There were 13 thoracolumbar injuries and one cervical spine injury. Distracting injuries in the eight patients with acute vertebral injuries included 13 bony fractures. Distracting injuries in those patients without vertebral injuries included bony fractures (333), lacerations (63), soft tissue contusions (62), head injuries (15), bony dislocations (12), abrasions (11), visceral injuries (8), dental injuries (5), burns (3), ligamentous injuries (3), amputation (1), and compartment syndrome (1). In conclusion, in patients with distracting injuries, bony fractures of any type were important for identifying patients with vertebral injuries. Other types of distracting injuries did not contribute to the sensitivity of the clinical screening criteria in the detection of patients with vertebral injuries.