Numerical investigation of the relative effect of disc bulging and ligamentum flavum hypertrophy on the mechanism of central cord syndrome

BackgroundThe pathogenesis of the central cord syndrome is still unclear. While there is a consensus on hyperextension as the main traumatic mechanism leading to this condition, there is yet to be consensus in studies regarding the pathological features of the spine (intervertebral disc bulging or ligamentum flavum hypertrophy) that could contribute to clinical manifestations.MethodsA comprehensive finite element model of the cervical spine segment and spinal cord was used to simulate high-speed hyperextension. Four stenotic cases were modelled to study the effect of ligamentum flavum hypertrophy and intervertebral disc bulging on the von Mises stress and strain.FindingsDuring hyperextension, the downward displacement of the ligamentum flavum and a reduction of the spinal canal diameter (up to 17%) led to a dynamic compression of the cord. Ligamentum flavum hypertrophy was associated with stress and strain (peak of 0.011 Mpa and 0.24, respectively) in the lateral corticospinal tracts, which is consistent with the histologic pattern of the central cord syndrome. Linear intervertebral disc bulging alone led to a higher stress in the anterior and posterior funiculi (peak 0.029 Mpa). Combined with hypertrophic ligamentum flavum, it further increased the stress and strain in the corticospinal tracts and in the posterior horn (peak of 0.023 Mpa and 0.35, respectively).InterpretationThe stenotic typology and geometry greatly influence stress and strain distribution resulting from hyperextension. Ligamentum flavum hypertrophy is a main feature leading to central cord syndrome.     

Recognition of prodromal cervical spondylotic myelopathy presenting in a U.S. Veteran referred to chiropractic for acute thoracic pain: A case report

ObjectiveTo highlight a patient who was referred to a VA chiropractic clinic for thoracic pain and upon physical exam was found to be myelopathic, subsequently requiring surgery.Clinical featuresA 58-year-old male attended a telephone interview with the VA chiropractic clinic for thoracic pain of 4 months duration; he denied neck pain, upper extremity symptoms or clumsiness of the feet or hands. At his in-person visit, he acknowledged frequently dropping items. The physical examination revealed signs of myelopathy including positive Hoffman's bilaterally, 3+ brisk patellar reflexes, and 5+ beats of ankle clonus bilaterally. He also had difficulty walking heel/toe.Intervention and outcomeCervical and thoracic radiographs were ordered and a referral was placed to the Physical Medicine and Rehabilitation (PM&R) Clinic for evaluation of the abnormal neurologic exam and suspicion of cervical spondylotic myelopathy (CSM). He was treated for 2 visits in the chiropractic clinic for his thoracic pain, with resolution of thoracic symptoms. No treatment was rendered to the cervical spine.The PM&R physician ordered a cervical MRI which demonstrated severe central canal stenosis and increased T2 signal within the cord at C5–C6, representing myelopathic changes. The PM&R specialist referred him to Neurosurgery which resulted in a C5-6, C6-7 anterior cervical discectomy and fusion.ConclusionThe importance of physical examination competency and routine thoroughness cannot be overstated. Swift identification of pathologic signs by the treating chiropractor resulted in timely imaging and surgical intervention.     

Biomechanical analysis on of anterior transpedicular screw-fixation after two-level cervical corpectomy using finite element method

BackgroundAnterior cervical trans-pedicle screw fixation was introduced to overcome some of the disadvantages associated with anterior cervical corpectomy and fusion. In vitro biomechanical studies on the trans-pedicle screw fixation have shown excellent pull-out strength and favorable stability. Comprehensive biomechanical performance studies on the trans-pedicle screw fixation, however, are lacking.MethodsThe control computed tomography images (C2-T2) were obtained from a 22-year-old male volunteer. A three dimensional computational model of lower cervical spine (C3-T1) was developed using computed tomography scans from a 22 year old human subject. The models of intact C3-T1 (intact group), anterior cervical trans-pedicle screw fixation (trans-pedicle group), and anterior cervical corpectomy and fusion (traditional group) were analyzed with using a finite element software. A moment of 1 N·m and a compressive load of 73.6 N were loaded on the upper surface and upper facet joint surfaces of C3. Under six conditions, four parameters such as the range of motion, titanium mesh plant stress, end-plate stress, and bone-screw stress were measured and compared on two treatment groups.FindingsCompared with the intact model, the range of motions for treatment groups were decreased. Compared with cervical corpectomy and fusion, the titanium plant, C4 upper end-plate and C7 lower end-plate stresses in trans-pedicle group were reduced. No significant difference was discovered on bone-screw stress between the two groups for lateral flexion and rotation, but bone-screw stress is smaller in trans-pedicle group when compared with traditional group. With exception of individual difference, trans-pedicle group had better biomechanical results than traditional group in range of motions, titanium mesh plant stress, end-plate stress and bone-screw stress.InterpretationThe trans-pedicle method has better biomechanical properties than the anterior cervical corpectomy and fusion making it a viable alternative for cervical fixations.     

Biomechanical comparison of spinal cord compression types occurring in Degenerative Cervical Myelopathy

BackgroundDegenerative Cervical Myelopathy results from spine degenerations narrowing the spinal canal and inducing cord compressions. Prognosis is challenging. This study aimed at simulating typical spinal cord compressions observed in patients with a realistic model to better understand pathogenesis for later prediction of patients' evolution.MethodsA 30% reduction in cord cross-sectional area at C5-C6 was defined as myelopathy threshold based on Degenerative Cervical Myelopathy features from literature and MRI measurements in 20 patients. Four main compression types were extracted from MRIs and simulated with a comprehensive three-dimensional finite element spine model. Median diffuse, median focal and lateral types were modelled as disk herniation while circumferential type additionally involved ligamentum flavum hypertrophy. All stresses were quantified along inferior-superior axis, compression development and across atlas-defined spinal cord regions.FindingsAnterior gray and white matter globally received the highest stress while lateral pathways were the least affected. Median diffuse compression induced the highest stresses. Circumferential type focused stresses in posterior gray matter. Along inferior-superior axis, those two types showed a peak of constraints at compression site while median focal and lateral types showed lower values but extending further.InterpretationMedian diffuse type would be the most detrimental based on stress amplitude. Anterior regions would be the most at risk, except for circumferential type where posterior regions would be equally affected. In addition to applying constraints, ischemia could be a significant component explaining the early demyelination reported in lateral pathways. Moving towards patient-specific simulations, biomechanical models could become strong predictors for degenerative changes.     

Degenerative cervical myelopathy

Cervical myelopathy is the most common cause of acquired spinal cord compromise. The concept of degenerative cervical myelopathy (DCM), defined as symptomatic myelopathy associated with degenerative arthropathic changes in the spine axis, is being introduced. Given its progressive nature, treatment options have to be chosen in a timely manner. Surgical options include anterior discectomy and fusion (ACDF), anterior corpectomy and fusion (ACCF), arthroplasty (in highly select cases), posterior laminectomy with/without fusion, and laminoplasty. Indications for each should be carefully considered in individual patients. Riluzole, a sodium-glutamate antagonist, is a promising option to optimize neurologic outcomes post-surgery and is being examined in the CSM-Protect Randomized Controlled Trial. Preoperative risk assessment is mandatory for prognostication. Sagittal alignment is known to play an important role to optimize surgical outcome. Guidelines for optimal management of DCM are in process. In principle, all but the mildest cases of DCM should be offered surgery for optimal outcome.     

Orientation entropy analysis of diffusion tensor in healthy and myelopathic spinal cord

The majority of nerve fibers in the spinal cord run longitudinally, playing an important role in connecting the brain to the peripheral nerves. There is a growing interest in applying diffusion tensor imaging (DTI) to the evaluation of spinal cord microarchitecture. The current study sought to compare the organization of longitudinal nerve fibers between healthy and myelopathic spinal cords using entropy-based analysis of principal eigenvector mapping. A total of 22 subjects were recruited, including 14 healthy subjects, seven cervical myelopathy (CM) patients with single-level compression, and one patient suffering from multi-level compression. Diffusion tensor magnetic resonance (MR) images of the cervical spinal cord were obtained using a pulsed gradient, spin-echo echo-planar imaging (SE-EPI) sequence with a 3T MR system. Regions of interest (ROIs) were drawn manually to cover the spinal cord, and Shannon entropy was calculated in principal eigenvector maps. The results revealed no significant differences in orientation entropy values along the whole length of cervical spinal cord in healthy subjects (C2-3: 0.73±0.05; C3-4: 0.71±0.07; C4-5: 0.72±0.048; C5-6: 0.71±0.07; C6-7: 0.72±0.07). In contrast, orientation entropy values in myelopathic cord were significantly higher at the compression site (0.91±0.03), and the adjacent levels (above: 0.85±0.03; below: 0.83±0.05). This study provides a novel approach to analyze the orientation information in diffusion MR images of healthy and diseased spinal cord. These results indicate that orientation entropy can be applied to determine the contribution of each compression level to the overall disorganization of principal nerve tracts of myelopathic spinal cord in cases with multi-level compression.     

Dynamics of spinal cord compression with different patterns of thoracolumbar burst fractures: Numerical simulations using finite element modelling

BackgroundIn thoracolumbar burst fractures, spinal cord primary injury involves a direct impact and energy transfer from bone fragments to the spinal cord. Unfortunately, imaging studies performed after the injury only depict the residual bone fragments position and pattern of spinal cord compression, with little insight on the dynamics involved during traumas. Knowledge of underlying mechanisms could be helpful in determining the severity of the primary injury, hence the extent of spinal cord damage and associated potential for recovery. Finite element models are often used to study dynamic processes, but have never been used specifically to simulate different severities of thoracolumbar burst fractures.MethodsPreviously developed thoracolumbar spine and spinal cord finite element models were used and further validated, and representative vertebral fragments were modelled. A full factorial design was used to investigate the effects of comminution of the superior fragment, presence of an inferior fragment, fragments rotation and velocity, on maximum Von Mises stress and strain, maximum major strain, and pressure in the spinal cord.FindingsFragment velocity clearly was the most influential factor. Fragments rotation and presence of an inferior fragment increased pressure, but rotation decreased both strains outputs. Although significant for both strains outputs, comminution of the superior fragment isn't estimated to influence outputs.InterpretationThis study is the first, to the authors' knowledge, to examine a detailed spinal cord model impacted in situ by fragments from burst fractures. This numeric model could be used in the future to comprehensively link traumatic events or imaging study characteristics to known spinal cord injuries severity and potential for recovery.     

Biomechanics of anterior plating failure in treating distractive flexion injury in the caudal subaxial cervical spine

BackgroundOperative level is a potential biomechanical risk factor for construct failure during anterior fixation for distractive flexion injury. No biomechanical study of this concept has been reported, although it is important in clinical management.MethodsTo explore the mechanism of this concept, a previously validated three-dimensional C2-T1 finite element model was modified to simulate surgical procedure via the anterior approach for treating single-level distractive flexion injury, from C2-C3 to C7-T1. Four loading conditions were used including no-compression, follower load, axial load, and combined load. Construct stability at the operative level was assessed.FindingsUnder these loading conditions with the head's weight simulated, segmental stability decreases when the operative level shifts cephalocaudally, especially at C6-C7 and C7-T1, the stress of screw-bone interface increases cephalocaudally, and in the same operative level, the caudal screws always carries more load than the cephalad ones. All these predicted results are consistent with failure patterns observed in clinical reports. In the contrast, under other loading conditions without the weight of head, no obvious segmental divergence was predicted.InterpretationThis study supports that the biomechanical mechanism of this phenomenon includes eccentric load from head weight during sagittal movements and difference of moment arms. Our study suggests that anterior fixation is not recommended for treating distractive flexion injury at the caudal segments of the subaxial cervical spine, especially at C6-C7 and C7-T1, because of the intrinsic instability in these segments. Combined posterior rigid fixation with anterior fixation should be considered for these segments.     

Comparative studies of cervical spine anterior stabilization systems - Finite element analysis

BackgroundThe object of the study was to assess the impact of one-level stabilization of the cervical spine for both anterior static and dynamic plates. Segments C2–C6 of the cervical spine, were investigated, from which was determined the stress and strain fields in the region of implantation and adjacent motion segments. The purpose was the comparison of changes that affect the individual stabilizers.MethodsFor testing we used finite element analysis. The cervical spine model takes into account local spondylodesis. The study includes both an intact anatomical model and a model with implant stabilization.FindingsThe analysis covered the model loaded with a moment of force for 1 Nm in the sagittal plane during movement. We compared both the modeled response of the whole fragment C2–C6 and the response of individual motion segments. The largest limitation of range of motion occurred after implantation with static plates. The study also showed that the introduction of the one-level stabilization resulted in an increase in stress in intervertebral disc endplates of adjacent segments.InterpretationThe results indicate that the increase in stress caused by stiffening may result in disorders in remodeling of bone structures. The use of dynamic plates showed improved continuity strains in the tested spine, thereby causing remodeling most similar to the physiological state and reducing the stresses in adjacent segments     

Strain behavior of malaligned cervical spine implanted with metal-on-polyethylene,metal-on-metal,and elastomeric artificial disc prostheses – A finite element analysis

BackgroundPostoperative alterations in cervical spine curvature (i.e. loss of lordotic angle) are frequently observed following total disc replacement surgery. However, it remains unclear whether such changes in lordotic angle are due to preoperative spinal deformities and/or prostheses design limitations. The objective of the study is to investigate strain and segmental biomechanics of the malaligned cervical spine following total disc replacement.MethodsThree disc prostheses were chosen, namely a metal-on-polyethylene, a metal-on-metal, and an elastomeric prosthesis, which feature different geometrical and material design characteristics. All discs were modelled and implanted into multi-segmental cervical spine finite element model (C3-C7) with normal, straight and kyphotic alignments. Comparative analyses were performed by using a hybrid protocol.FindingsThe results indicated that as the spine loses lordotic alignment, the prosthesis with elastomeric core tends to produce significantly larger flexion range of motion (difference up to 6.1°) than metal-on-polyethylene and metal-on-metal prostheses. In contrast, when the treated spine had normal lordotic alignment, the range of motion behaviors of different prostheses are rather similar (difference within 1.9°). Large localized strains up to 84.8% were found with the elastomeric prosthesis, causing a collapsed anterior disc space under flexion loads.InterpretationChanges in cervical spinal alignments could significantly affect the surgical-level range of motion behaviors following disc arthroplasty; the in situ performance was largely dependent on the designs of the artificial disc devices in particular to the material properties.     

下颈椎前路内固定联合后路经关节金属螺钉置入固定的生物力学稳定性

背景:对退变性颈椎管狭窄单纯采用前路椎体次全切除或椎间盘切除或单纯后路单开门椎管扩大成行均不能彻底完成脊髓减压和脊柱三柱稳定。目的:探讨下颈椎前路固定联合后路经关节螺钉固定的生物力学稳定性。方法:正常成人尸体颈椎标本,每具分别制作以下两种模型:①经后路C3～C7单开门和下颈椎前路C5椎体次全切除钛网支撑植骨、ORION内固定模型(对照组)。②经后路C3～C7单开门和经关节螺钉内固定及下颈椎前路C5椎体次全切除钛网内植骨、ORION内固定模型(实验组)。结果与结论:实验组在前屈、后伸、左、右侧屈及左、右旋转移位角度均小于对照组(P<0.001)。提示:①在生物力学实验中,下颈椎前路固定联合后路经关突节螺钉固定的生物力学性能优良,对抗前屈、后伸、左、右旋转的作用力更强,颈椎可获得更可靠的稳定性。②下颈椎前路固定联合后路经关节螺钉固定在对抗颈椎前屈运动时力学稳定性更为强大。     

平山病的动态磁共振成像研究

目的通过颈椎中立位及过屈位磁共振扫描观察平山病患者颈髓形态的变化,进一步分析平山病诊断的影像学依据,并初步探讨平山病的发病机制。方法选择正常人无颈椎病史30例,以及确诊平山病患者20例,进行颈椎中立位及过屈位磁共振扫描,选择C6水平分别在两种体位测量颈髓正中线前后径,另外测量过屈位相邻两个椎体后缘的角度。结果患者C6水平颈髓前后径中立位(Dn)及过屈位(Df)分别为(0.542±0.076)cm、(0.418±0.067)cm,正常对照Dn及Df分别为(0.670±0.049)cm、(0.595±0.047)cm,患者均较正常人小(P<0.01),且过屈位颈髓前后径患者较正常人变小更为明显,且以一侧变扁为著(P<0.01)。过屈位相邻椎体后缘成角依次为AC34(3.0±2.0)°、AC45(6.7±2.2)°、AC56(11.8±2.3)°、AC67(8.6±3.7)°,下颈段大于上颈段(AC56>AC67>AC45>AC34)。结论磁共振成像可以明确显示平山病形态学改变,是诊断平山病的重要依据之一,下颈段颈椎成角较大,可能是造成平山病集中在下颈段脊髓的原因之一。     

[18F]-Fluorodeoxyglucose–Positron Emission Tomography in Patients With Active Myelopathy

ObjectiveTo report and compare spinal cord [¹⁸F]-fluorodeoxyglucose–positron emission tomography (FDG-PET) metabolism in 51 patients with active myelopathy.Patients and MethodsWe retrospectively identified patients from January 1, 2001, through December 31, 2011, with active myelopathy in whom FDG-PET was performed. Inclusion criteria were (1) intramedullary myelopathy, (2) neoplastic/inflammatory etiology, and (3) FDG-PET performed after myelopathy onset. Exclusion criteria were (1) extramedullary myelopathy, (2) radiation-associated myelopathy, (3) no pathological confirmation of neoplasm, and (4) inactive myelopathy. Diagnostic categories of nonsarcoid inflammatory, neoplastic, and neurosarcoid were based on their final myelopathic diagnosis. Two radiologists who independently assessed FDG-PET for spinal cord hypermetabolism and maximum standardized uptake value (SUVmax) were blinded to the underlying etiology.ResultsFifty-one patients (53% women) with a median age of 60 years (range, 20-82 years) were included. Inflammatory myelopathic diagnoses (n=24) were as follows: paraneoplastic (n=13), autoimmune/other (n=5), inflammatory demyelinating (n=4), and transverse myelitis (n=2). Neoplastic diagnoses (n=21) were as follows: intramedullary metastases (n=12), intramedullary lymphoma/leukemia (n=7), and primary intramedullary neoplasm (n=2). Six patients had neurosarcoid myelopathy. Spinal cord hypermetabolism was more common with neoplastic myelopathy than with nonsarcoid inflammatory myelopathy (17 of 21 [81%] vs 6 of 24 [25%]; P<.001). Agreement between radiologist’s assessments was excellent (κ=0.88). Median SUVmax was greater in neoplastic than in nonsarcoid inflammatory causes of myelopathy (3.3 g/mL vs 1.9 g/mL; P<.001). The FDG-PET hypermetabolism was seen in 3 of the 6 patients (50%) with neurosarcoid myelopathy (median SUVmax, 2.6 g/mL; range, 1.8-12.2 g/mL).ConclusionSpinal cord FDG-PET hypermetabolism in patients with active myelopathy may be reliably detected and was more common in neoplastic than in inflammatory myelopathies in this study. Future investigation of spinal cord FDG-PET is indicated to assess its potential contributions in evaluating active myelopathies.     

MRI观察成人无骨折、脱位型颈髓损伤

目的 分析成人无骨折、脱位颈椎外伤合并颈脊髓损伤的MR表现及其临床意义.方法 收集该病患者38例,入院时均行颈椎X线、CT及MR检查,其中男32例,女6例,年龄24～62岁,平均(42.0±0.4)岁.结果 本组病例X线、CT及MR检查均未见颈椎骨折及脱位.脊髓MRI信号改变包括脊髓信号无改变4例,髓内水肿30例,髓内出血9例,脊髓软化或囊性变4例以及增强后有强化13例.其他MRI表现包括颈椎后纵韧带骨化或颈椎间盘退变或损伤后突出等,为脊髓受压迫的原因.结论 MRI可为无骨折、脱位型颈脊髓损伤患者的诊断与正确治疗提供依据.MRI无信号改变或仅有水肿表现者预后较好,髓内出血或者异常强化者预后较差.     

两种前路减压植骨融合并钛钢板置入内固定治疗相邻两个节段脊髓型颈椎病的比较

背景:颈椎前路手术减压方法主要包括环锯法颈椎前路减压融合、前路椎间盘切除植骨融合与钛板置入内固定和前路椎体次全切除植骨融合并置入钛板内固定。目的:比较两种不同的颈椎前路减压植骨融合并钛钢板置入内固定治疗相邻两个节段脊髓型颈椎病的临床效果及生物相容性反应。方法:相邻两节段脊髓型颈椎病患者54例按数字表法随机分为2组。27例采用前路椎间盘切除植骨融合并钛板置入内固定,27例采用前路椎体次全切除植骨融合并钛板置入内固定。比较两组融合节段高度和Cobb’s角、神经功能改善率、置入后并发症发生率。结果与结论:两组各有4例因失随访或随访时间不到2年未纳入结果。前路椎间盘切除植骨融合并钛板置入内固定组23例随访26～48个月;前路椎体次全切除植骨融合并钛板置入内固定组23例随访24～53个月。两组住院时间,融合节段高度,脊髓功能改善率,治疗优良率和有效率差异无显著性意义(P>0.05)。后组手术时间、术中出血量均高于前组(P<0.05),融合节段Cobb’s角的改善也较优(P<0.05),但供骨区并发症发生率低(P<0.05)。提示两种方法治疗相邻两个节段脊髓型颈椎病均取得满意的疗效,前路椎间盘切除植骨融合并钛板置入内固定具有手术时间短、术中出血量少、明显改善融合节段Cobb’s角、椎体骨质保留多、减少供骨区并发症等优点。     

C_4～C_6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。     

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。     

下颈椎前路内固定联合后路经关节金属螺钉置入固定的生物力学稳定性

背景：对退变性颈椎管狭窄单纯采用前路椎体次全切除或椎间盘切除或单纯后路单开门椎管扩大成行均不能彻底完成脊髓减压和脊柱三柱稳定。目的：探讨下颈椎前路固定联合后路经关节螺钉固定的生物力学稳定性。方法：正常成人尸体颈椎标本,每具分别制作以下两种模型：①经后路C3～C7单开门和下颈椎前路C5椎体次全切除钛网支撑植骨、ORION内固定模型（对照组）。②经后路C3～C7单开门和经关节螺钉内固定及下颈椎前路C5椎体次全切除钛网内植骨、ORION内固定模型（实验组）。结果与结论：实验组在前屈、后伸、左、右侧屈及左、右旋转移位角度均小于对照组（P〈0.001）。提示：①在生物力学实验中,下颈椎前路固定联合后路经关突节螺钉固定的生物力学性能优良,对抗前屈、后伸、左、右旋转的作用力更强,颈椎可获得更可靠的稳定性。②下颈椎前路固定联合后路经关节螺钉固定在对抗颈椎前屈运动时力学稳定性更为强大。     

二种颈前路减压术治疗多节段脊髓型颈椎病疗效分析

目的：比较二种不同颈前路减压术式对治疗多节段脊髓型颈椎病的手术疗效及影像学结果。方法2008年5月至2011年11月行颈前路减压术治疗多节段脊髓型颈椎病98例,根据手术方式不同分为二组：前路颈椎间盘切除减压融合术（anterior cervical discectomy with fusion,ACDF）（A组）和前路椎体次全切减压融合术（anterior cervical corpectomy with fusion,ACCF）（B组）。所有患者术前、术后不同时期采用JOA评分评估神经功能情况,X线评价颈椎曲度、椎间高度变化情况。结果所有患者均获得术后17个月的随访。术后1个月、术后17个月JOA评分较术前之间差异均有统计学意义（P〈0.05）,而组间比较差异无统计学意义（P〉0.05）。术后1个月、术后17个月COBB角、椎间高度与术前之间差异均有统计学意义（P〈0.05）,但B组术后17个月COBB角、椎间高度与术后1个月之间差异有统计学意义（P〈0.05）。结论前路颈椎间盘切除减压融合术和前路椎体次全切除减压融合术均可有效地治疗多节段脊髓型颈椎病,但前路椎体次全切除减压融合术后颈椎稳定性比前路颈椎间盘切除减压融合术差。     

两种前路减压植骨融合并钛钢板置入内固定治疗相邻两个节段脊髓型颈椎病的比较

背景：颈椎前路手术减压方法主要包括环锯法颈椎前路减压融合、前路椎间盘切除植骨融合与钛板置入内固定和前路椎体次全切除植骨融合并置入钛板内固定。目的：比较两种不同的颈椎前路减压植骨融合并钛钢板置入内固定治疗相邻两个节段脊髓型颈椎病的临床效果及生物相容性反应。方法：相邻两节段脊髓型颈椎病患者54例按数字表法随机分为2组。27例采用前路椎间盘切除植骨融合并钛板置入内固定,27例采用前路椎体次全切除植骨融合并钛板置入内固定。比较两组融合节段高度和Cobb’s角、神经功能改善率、置入后并发症发生率。结果与结论：两组各有4例因失随访或随访时间不到2年未纳入结果。前路椎间盘切除植骨融合并钛板置入内固定组23例随访26～48个月;前路椎体次全切除植骨融合并钛板置入内固定组23例随访24～53个月。两组住院时间,融合节段高度,脊髓功能改善率,治疗优良率和有效率差异无显著性意义（P〉0.05）。后组手术时间、术中出血量均高于前组（P〈0.05）,融合节段Cobb’s角的改善也较优（P〈0.05）,但供骨区并发症发生率低（P〈0.05）。提示两种方法治疗相邻两个节段脊髓型颈椎病均取得满意的疗效,前路椎间盘切除植骨融合并钛板置入内固定具有手术时间短、术中出血量少、明显改善融合节段Cobb’s角、椎体骨质保留多、减少供骨区并发症等优点。