椎间盘疝入胸腰段骨折椎体导致骨折畸形愈合及椎间隙高度下降

目的：分析损伤且疝入胸腰段骨折椎体的椎间盘组织对骨折愈合、椎体骨缺损体积变化及椎间隙高度影响的临床特点。方法：自2016年4月至2020年4月，行椎弓根钉棒系统复位内固定治疗140例胸腰段单椎体骨折合并上邻椎间盘损伤患者，男83例，女57例，年龄19~58（39.33±10.26）岁。术后6、12、18个月定期门诊复诊随访。损伤椎间盘组织未疝入骨折椎体患者为对照组，椎间盘损伤且疝入骨折椎体患者为观察组。通过不同回访时间下胸腰段正侧位X线片、CT及MRI扫描图像，分析计算骨折椎体楔变角、矢状位后凸角和上邻椎间隙高度变化，椎体复位后骨折愈合及骨缺损体积的变化以及椎间盘退变等级变化；并通过视觉模拟评分（visual analogue scale，VAS）、日常生活功能障碍指数（Oswestry disability index，ODI）评估患者预后；最后综合分析不同组别之间上述结果的差异性。结果：所有患者术后伤口正常愈合，无并发症发生。共87例患者获得完整回访资料，至少回访至内固定术后18个月。胸腰段正侧位X线发现观察组患者在复位内固定手术18个月后，椎体楔变角、矢状位后凸角增加及上邻椎间隙高度下降均大于对照组（P<0.05）。CT扫描发现观察组患者椎体复位术后12个月骨折畸形愈合并形成与椎间隙相通的骨缺损"空腔"，且其体积较前明显增大（P<0.05）。MRI扫描发现术后12个月观察组损伤椎间盘退变率较对照组严重且差异具有统计学意义（P<0.05）。但各时间下腰背部疼痛VAS及ODI差异无统计学意义。结论：损伤椎间盘组织疝入骨折椎体，使骨折周围骨质吸收骨缺损体积增大，形成与椎间隙相通的畸形愈合"空腔"，这可能是内固定装置去除后椎体楔变角、矢状面后凸角增加和椎间隙高度下降的主要原因。     

The degeneration of adjacent intervertebral discs negatively influence union rate of osteoporotic vertebral fracture: A multicenter cohort study

Background

With the increasing aging population in developed countries, there has been an associated increased prevalence of osteoporotic vertebral fracture (OVF). Many previous reports have attempted to predict the risk of delayed union associated with OVF. However, the role of endplate failure and the degeneration of adjacent intervertebral discs, and their association with delayed union has received little attention. The aim of this study was to evaluate the endplate fracture and disc degeneration rank as risk factors for delayed union.

Development of a rat model with lumbar vertebral endplate lesion

Purpose

Vertebral endplate lesion (EPL) caused by severe disc degeneration is associated with low back pain. However, there is no suitable animal model to elucidate the pathophysiology of EPL. This study aimed to develop a rat model of EPL and evaluate rat behavior and imaging and histological findings.

Methods

The L4-5 intervertebral discs of Sprague–Dawley rats were transperitoneally removed, except for the outer annulus fibrosus and cartilage endplate, in the EPL group. The L4-5 discs were not removed and simply exposed in the sham group. Changes around the vertebral endplate on magnetic resonance imaging (MRI) and computed tomography (CT) were evaluated. Additionally, pain-related behavioral and histological assessments were performed.

Results

In the EPL group, a low-signal area around the vertebral endplate was observed on T1-weighted and T2-weighted fat-saturated MRI at 8 weeks or later after surgery. In the same group, CT showed osteosclerosis around the vertebral endplate at 12 weeks after surgery. The sham group did not show abnormal imaging features on the MRI and CT. Behavioral evaluation showed that the EPL group had a significantly longer grooming time than the sham group. Conversely, the 12-week postoperative locomotion time and the 1- and 12-week postoperative standing times were significantly shorter in the EPL group than in the sham group. Histological evaluation showed a high degree of vertebral endplate degeneration and an increased number of osteoclasts and proportion of nerve fibers expressing calcitonin gene-related peptide in the EPL group compared to those in the sham group.

Conclusion

Our rat EPL model showed pain-related behavioral patterns and an increased expression of pain-related neuropeptide. This model could contribute to the study of the pathophysiology of EPL and will help in the treatment of low back pain in the future.

     

Effect of endplate reduction on endplate healing morphology and intervertebral disc degeneration in patients with thoracolumbar vertebral fracture

Objective

To determine the effect of endplate reduction on the final healing morphology and degenerative changes in intervertebral discs.

Methods

Forty-eight patients with single-level thoracolumbar fractures with endplate injury were included. All patients underwent posterior reduction and pedicle screw fixation, and postoperative imaging was used to determine whether endplate reduction was successful. The healing morphology of the endplate was divided into three types: increased endplate curvature, irregular healing and traumatic Schmorl node. MRI was performed at baseline and at the last follow-up evaluation to observe changes in disc degeneration (disc height and nucleus pulposus signal) and Modic changes.

Results

The reduction rate in the central area was significantly lower than that in the peripheral area (P = 0.017). In patients with successful reduction, 90.9% (20/22) of the endplates healed with increased curvature. In patients with an unsuccessful endplate reduction, 63.4% (26/41) of the endplates healed irregularly, and 34.1% (14/41) of the endplates formed traumatic Schmorl nodes. Endplate reduction was closely related to the final healing morphology of the endplate (P < 0.001), which had a significant protective effect on the degeneration of the intervertebral disc. At the last follow-up evaluation, there was no statistically significant correlation between different endplate healing morphologies and new Modic changes.

Conclusions

The reduction rate in the central area is significantly lower than that in the peripheral area. Although all of the intervertebral discs corresponding to fractured endplates had degenerated to different degrees, successful endplate fracture reduction can obviously delay the degeneration of intervertebral discs.

     

Radiological study on disc degeneration of thoracolumbar burst fractures treated by percutaneous pedicle screw fixation

Objective

To examine disc degeneration at levels adjacent and next adjacent to the fractured vertebra and to analyses, if the disc degeneration is determined by the endplate fracture.

Summary of background data

Thoracolumbar burst fracture is one of the most common spinal injuries. The diagnostic (clinical and imaging) approach and treatment of a fractured vertebra is well established; however, some controversy remains. The associated disc degeneration is less well known after 9–12 months of the short segment pedicle screw fixations. There is a major controversy whether spinal trauma with vertebral endplate fractures can result in posttraumatic disc degeneration. No study to date, however, has assessed disc degeneration of the AO type A3 thoracolumbar fractures without neurologic deficits after pedicle screw fixations.

Methods

Twenty-six patients with single-level AO type A3 thoracolumbar fractures and no neurological deficit were treated by using postural reduction and short segment percutaneous pedicle screw fixation. No laminectomy and fusion were performed. Implants were removed 9–12 months after the first operation. The thoracolumbar magnetic resonance imaging (MRI) was used to assess disc degeneration at levels adjacent and next adjacent to the fractured vertebra before the first operation and after the second operation in a retrospective study.

Results

After the instrumentation removal, new disc degeneration was usually found at level adjacent to the cranial endplate of fractured vertebra by MRI examination in 24 patients. The average Pfirrmann grade of degenerative discs adjacent to the cranial fractured endplates deteriorated from 2.1 pre-operatively to 3.4 after the second operation. No change of disc degeneration was seen at the caudal disc space adjacent to the fractured vertebra and the levels next adjacent to the fractured vertebra. The discs next adjacent to the fractured vertebra were showed to be relatively normal without changes of degeneration during the study period.

Conclusions

Disc degeneration usually occurs at level adjacent to the fractured endplate of thoracolumbar burst fractures. Endplate fracture is strongly associated with disc degeneration. No correlation between fixation level and disc degeneration is seen in this study.     

终板下椎体缺血诱导兔椎间盘退行性变模型的建立及终板中内皮素1的表达

目的通过终板下注射无水乙醇阻碍椎体-终板营养,建立一种新型兔腰椎椎间盘退行性变模型,并观察终板退行性变过程中内皮素1(ET-1)的表达情况。方法健康4月龄新西兰兔32只,随机分成4组,每组8只,选取L5,6椎体(对应L4/L5及L5/L6椎间盘)注射300μL无水乙醇,选取L4椎体(对应L3/L4椎间盘)注射磷酸盐缓冲液(PBS)作为实验对照,L7椎体(对应L6/L7椎间盘)未注入任何物质作为正常对照。其中1组造模后1个月提取软骨终板细胞,行免疫细胞化学染色检测ET-1表达;余3组分别于造模后1、3和5个月进行椎间盘X线和MRI检查,取椎间盘组织行HE染色观察形态学改变,免疫组织化学染色观察ET-1表达。结果注射无水乙醇后,随着时间进展,X线片显示椎间隙高度显著下降、椎间隙变窄、边缘骨赘增生,MRI T2WI显示椎间盘低信号;苏木精-伊红染色(HE)显示终板的生长板厚度变薄,终板结构破损,同时软骨终板细胞退化、直至消失,髓核中细胞发生转化(由空泡细胞转变为软骨样细胞,进而形成纤维软骨样细胞)造成髓核纤维化,纤维环结构排列紊乱、纤维化程度逐步加重;免疫组织化学染色显示,发生退行性变的终板组织内有ET-1表达,但随着退行性变加剧,ET-1表达强度下降;提取的退行性变软骨终板细胞(造模后1个月)也显示细胞质内ET-1强表达。结论通过注射无水乙醇阻碍椎体-终板营养途径可成功建立兔椎间盘退行性变模型,终板退行性变过程中伴随ET-1的表达。     

Disc degeneration contributes to the denser bone in the subendplate but not in the vertebral body in patients with lumbar spinal stenosis or disc herniation

BACKGROUND CONTEXTIt is commonly believed that decreased bone quality would lead to endplate degeneration and arthritic changes in the facet joints, and thus accelerated disc degeneration (DD). However, some more detailed studies of vertebral bone structure have found that bone mineral density (BMD) in the vertebral body is increased rather than decreased in moderate or greater disc degeneration. The relationship between BMD and DD still needs further study. MRI-based vertebral bone quality scores have been shown to be effective in reflecting BMD, rendering a new way to evaluate the changes of vertebral body bone with DD using MRI alone.PURPOSETo evaluate MRI-based vertebral bone quality and Pfirrmann grades in patients with lumbar spinal stenosis or disc herniation, and to identify if DD is associated with denser bone around the endplate.STUDY DESIGN/SETTINGA single-center, retrospective cohort study.PATIENT SAMPLEA total of 130 patients with lumbar disc herniation and lumbar spinal stenosis from January 2019 to November 2020 who had a complete dual-energy X-ray absorptiometry scan and noncontrast lumbosacral spine MRI data.OUTCOME MEASURESThe vertebral bone quality score (VBQ) and sub-endplate bone quality score (EBQ) was calculated as a ratio of the signal intensity of the vertebral bodies and sub-endplate regions to the signal intensity of the cerebrospinal fluid at L3 on the mid-sagittal T1-weighted MRI images, respectively. The Pfirrmann grades of the lumbar discs were assessed as well.METHODSThe age, gender, body mass index, and T-score of the lumbar spine of the patients were collected. The degeneration grades of the lumbar discs were evaluated according to the Pfirrmann classification. VBQ and EBQ were measured through T1-weighted lumbar MRI. The VBQ and EBQ scores were compared between cranial and caudal sides. The correlation between MRI-based bone quality and DD was calculated. A linear regression model was used to examine the association between DD and adjacent EBQ and VBQ.RESULTSThis study included 569 lumbar segments from 130 inpatients. Cranial and caudal EBQ decreased with the increase of the Pfirrmann grade. The discs with Pfirrmann grade 5 had significantly lower caudal EBQ than the discs with Pfirrmann grades 2, 3, and 4. In the osteoporosis patients, the Pfirrmann grades negatively correlated both with the cranial EBQ and caudal EBQ. Pfirrmann grade greater than 4 was an independent contributor to the cranial EBQ, whereas greater than 3 was an independent contributor to the caudal EBQ.CONCLUSIONSDisc degeneration grades correlated with the EBQ but not with the VBQ. In patients with lumbar spinal stenosis or disc herniation, DD contributes to the denser bone in the sub-endplate, but not in the whole vertebral body.     

A morphological study of lumbar vertebral endplates: radiographic, visual and digital measurements

Purpose

Clinical observations suggest that endplate shape and size are related to complications of disc arthroplasty surgery. Yet, the morphology of the vertebral endplate has not been well defined. This study was conducted to characterize the morphology of lumbar vertebral endplates and to quantify their morphometrics using radiographic, visual and digital measures.

Methods

A total of 591 vertebral endplates from 76 lumbosacral spines of men were studied (mean age 51.3 years). The shape of the vertebral endplates was classified as concave, flat and irregular, and was evaluated from both radiographs and cadaveric samples. Each endplate was further digitized using a laser scanner to quantify diameters, surface area and concavity for the whole endplate and its components (central endplate and epiphyseal rim). The morphological characteristics and morphometrics of the vertebral endplates were depicted.

Results

In both radiographic and visual assessments, more cranial endplates (relative to the disc) were concave and more caudal endplates were flat at all disc levels (p < 0.001). On average, the mean concavity depth was 1.5 mm for the cranial endplate and 0.7 mm for the caudal endplate. From L1/2 down to L5/S1 discs, the vertebral endplate gradually changed into a more oval shape. The central endplate was approximately 70 % of the diameter of the whole endplate and the width of the epiphyseal rim varied from 3 to 7 mm.

Conclusions

There is marked morphological asymmetry between the two adjacent endplates of a lumbar intervertebral disc: the cranial endplate is more concave than the caudal endplate. The size and shape of the vertebral endplate also vary considerably between the upper and lower lumbar regions.     

Changes of the adjacent discs and vertebrae in patients with osteoporotic vertebral compression fractures treated with or without bone cement augmentation

BACKGROUND CONTEXTAlthough vertebral augmentation with bone cement has been commonly used to treat symptomatic osteoporotic vertebral compression fractures, relatively little is known about the impact of augmentation on the adjacent spinal components.PURPOSETo determine the imaging effects of vertebral augmentation on the adjacent discs, the augmented vertebra, and the involved spinal segment.STUDY DESIGNRetrospective radiographic study.PATIENT SAMPLEPatients with acute osteoporotic vertebral compression fractures who underwent vertebral augmentation or nonoperative treatments.OUTCOME MEASURESOn baseline and follow-up mid-sagittal T2W magnetic resonance images, quantitative measurements of disc degeneration, including disc height, bulging, and signal, vertebral height, wedge angle, and segmental kyphotic angle were acquired.METHODSLumbar spine magnetic resonance images of patients with acute osteoporotic vertebral compression fractures at a local hospital in Eastern China between 2010 and 2017 were reviewed. Student's t-tests and χ² tests were used to examine the differences of baseline and changes over time between vertebrae underwent vertebral augmentation and those did not. Paired t-tests were used to examine the differences between baseline and follow-up to study the changes of adjacent disc degeneration, creep deformity of the vertebra and progression of segmental kyphosis.RESULTSThere were 112 acute vertebral compression fractures (72 treated with kyphoplasty and 40 with nonoperative treatments) in 101 subjects. At final follow-up (mean 21.5 months), the cranial disc of the augmented vertebra decreased in height (p<.001), and both cranial and caudal discs decreased in signal intensity (p≤.02). The discs in the nonoperative group did not undergo such degenerative changes. For the fractured vertebra, vertebral height significantly decreased (p<.01 for both) and vertebral wedge angle significantly increased (p≤.01 for both), regardless of augmentation treatment or not. Segmental kyphotic angle significantly increased in vertebral fractures that underwent vertebral augmentation (p<.001), but not in those underwent nonoperative treatments.CONCLUSIONSPatients that underwent vertebral augmentation had more advanced disc degeneration at adjacent disc levels as compared to those without augmentation. The fractured vertebral body height decreased and the wedge angle increased, regardless of vertebral augmentation treatment or not. Vertebral augmentation may be associated with increased creep deformity of the adjacent vertebra and the progression of segmental kyphosis.     

低温等离子体射频消融术应用于椎间松解的组织学观察

目的评价低温等离子体射频消融术应用在椎间松解及其自然转归的组织学变化。方法将12只2.0~2.5月龄的健康雌性山羊随机分为低温等离子体消融组(消融组,n=6)和传统胸椎椎间盘切除组(传统组,n=6)。每只动物均处理中段6个胸椎椎间盘(T_5/T_6/T_7/T_8/T_9/T_(10)/T_(11)),光镜下分别比较2种术式术后即刻和术后12周自然转归的组织学变化。结果消融组术后即刻椎间盘组织(纤维环,髓核和软骨终板)基本被去除,仅在软骨终板和骨性终板交界处残留一薄层软骨终板,表面光整,厚度均匀,周围组织细胞形态基本正常。传统组术后即刻纤维环、软骨终板有不同程度的剩余,骨性终板无明显破坏,松解面凹凸不平,刀痕周围的组织细胞形态正常。消融组术后12周显微镜下见椎间残留有部分薄层软骨终板已被不同程度的钙化,椎间前后缘融合稍差;椎间中部被大量成纤维细胞连接,软骨细胞增生更加明显,椎体骨小梁和终板下骨小梁之间无明确的界限,潮标前移变薄。传统术后12周显微镜下见软骨终板大部分消失,仅在近椎体后缘残留;终板下骨小梁排列不规则,上下终板下骨小梁之间未呈连续性生长,而是被大量由软骨细胞和成纤维细胞组成的组织连接,其中可见新生的毛细血管,上下潮标不对称并前移。结论采用低温等离子体消融术行椎间准备可以较好地去除软骨终板,处理后的终板面较传统组光整,且对周围健康组织影响小,和传统组都能获得早期的椎间融合倾向。     

Intervertebral Disc Degeneration Is Associated With Aberrant Endplate Remodeling and Reduced Small Molecule Transport

The intervertebral disc is the largest avascular structure in the body, and cells within the disc rely on diffusive transport via vasculature located within the vertebral endplate to receive nutrients, eliminate waste products, and maintain disc health. However, the mechanisms by which small molecule transport into the disc occurs in vivo and how these parameters change with disc degeneration remain understudied. Here, we utilize an in vivo rabbit puncture disc degeneration model to study these interactions and provide evidence that remodeling of the endplate adjacent to the disc occurs concomitant with degeneration. Our results identify significant increases in endplate bone volume fraction, increases in microscale stiffness of the soft tissue interfaces between the disc and vertebral bone, and reductions in endplate vascularity and small molecule transport into the disc as a function of degenerative state. A neural network model identified changes in diffusion into the disc as the most significant predictor of disc degeneration. These findings support the critical role of trans-endplate transport in disease progression and will improve patient selection to direct appropriate surgical intervention and inform new therapeutic approaches to improve disc health. © 2020 American Society for Bone and Mineral Research. Published 2020. This article is a U.S. Government work and is in the public domain in the USA.     

Effects of unisegmental disc compression on adjacent segments: an in vivo animal model

It is controversial whether fusion of discs in the spine leads to increased degeneration on the remaining discs or whether the degenerative changes are merely a part of the inevitable natural history process. To determine the effects of unisegmental compression and subsequent recovery on adjacent segments, we studied histology, radiology and intradiscal pressure using an in vivo rabbit model. Fifteen New Zealand rabbits were divided in to three groups of five. In the first group, the intervertebral disc L4–L5 of the lumbar spine was axially loaded for 28 days with an external loading device. In the second group, the intervertebral disc was compressed for 28 days and allowed to recover for an equal amount of time, with the loading device removed. Five animals underwent a sham operation, in which the external loading device was situated, but their discs remained unloaded for 28 days. The intradiscal pressure was determined in the loaded discs as well as in the cranial and caudal adjacent discs. Lateral radiographs were taken from each subjected intervertebral disc with adjacent vertebral bodies and the cranial and caudal adjacent segments. The compressed discs showed lower intradiscal pressure in comparison with the control group, which remained unloaded. In the cranial and caudal discs adjacent to the loaded discs the average intradiscal pressure was similar to the unloaded controls. The loaded discs demonstrated a significant decrease in disc space. No discs adjacent to the loaded discs changed in height. The lamellar architecture of the inner, middle, and outer annulus became more disorganized in the loaded discs. The nucleus pulposus showed increase of mucoid degeneration and increased cell death. Intervertebral discs from the control group and the adjacent discs to the compressed discs maintained their normal morphology. This study shows that mechanical loading of discs in the spine can cause rapid degeneration. Adjacent discs, however, did not change in terms of radiology, intradiscal pressure, or histology.     

Dynamic adaptation of vertebral endplate and trabecular bone following annular injury in a rat model of degenerative disc disease

Background Context

Degenerative disc disease (DDD) is associated with longitudinal remodeling of paravertebral tissues. Although chronic vertebral changes in advanced stages of DDD are well-studied, very little data exists on acute vertebral bone remodeling at the onset and progression of DDD.

Age changes in lumbar vertebrae and intervertebral discs

Reduction of stature in old age has been attributed to loss of disc height. A measurement study of 204 cadaveric lumbar spines from subjects ranging in age from one day to 97 years confirmed data on loss of "spinal stature" but could not confirm a loss of disc height. With aging, there is a progressive increase in vertebral end-plate concavity, associated with decreased bone density. These changes are more evident and take place earlier in females than in males. In the cancellous bone of vertebral bodies, a decrease in the number of horizontal trabecular "cross braces" leads to fracture of the vertical weight-bearing "beams" supporting the vertebral endplate. The intervertebral discs expand centrally and become increasingly convex. Measurements of average disc height demonstrate that loss of disc height is unusual in a normal, aging population. Only a minority of lower lumbar discs from elderly subjects show "thinning" and degeneration (beyond Rolander's Grade 2). Thus, loss of stature in the elderly is attributable to loss in vertebral height rather than loss in disc height. Dessication and thinning of discs, or discs that "bulge like underinflated automobile tires" are not typical of elderly spines.     

退变大鼠颈椎间盘细胞凋亡的实验研究

目的动态观察大鼠颈部动静力失去平衡后颈椎间盘细胞凋亡的改变.方法建立动静力失衡性颈椎间盘退变模型,透射电镜、TUNEL法、流式细胞仪PI法检测造模3、5、7月后椎间盘细胞凋亡程度.结果退变椎间盘内有典型凋亡的细胞,以软骨细胞为主.与对照组比较,各个模型组软骨细胞凋亡指数明显升高(P＜0.01);模型组间比较,5月、7月较3月细胞凋亡指数明显升高(P＜0.01).结论退变椎间盘软骨细胞凋亡数目增多可能是椎间盘退变的机理之一.     

Mechanical initiation of intervertebral disc degeneration

STUDY DESIGN: Mechanical testing of cadaveric lumbar motion segments. OBJECTIVES: To test the hypothesis that minor damage to a vertebral body can lead to progressive disruption of the adjacent intervertebral disc. SUMMARY OF BACKGROUND DATA: Disc degeneration involves gross structural disruption as well as cell-mediated changes in matrix composition, but there is little evidence concerning which comes first. Comparatively minor damage to a vertebral body is known to decompress the adjacent discs, and this may adversely affect both structure and cell function in the disc. METHODS: In this study, 38 cadaveric lumbar motion segments (mean age, 51 years) were subjected to complex mechanical loading to simulate typical activities in vivo while the distribution of compressive stress in the disc matrix was measured using a pressure transducer mounted in a needle 1.3 mm in diameter. "Stress profiles" were repeated after a controlled compressive overload injury had reduced motion segment height by approximately 1%. Moderate repetitive loading, appropriate for the simulation of light manual labor, then was applied to the damaged specimens for approximately 4 hours, and stress profilometry was repeated a third time. Discs then were sectioned and photographed. RESULTS: Endplate damage reduced pressure in the adjacent nucleus pulposus by 25% +/- 27% and generated peaks of compressive stress in the anulus, usually posteriorly to the nucleus. Discs 50 to 70 years of age were affected the most. Repetitive loading further decompressed the nucleus and intensified stress concentrations in the anulus, especially in simulated lordotic postures. Sagittal plane sections of 15 of the discs showed an inwardly collapsing anulus in 9 discs, extreme outward bulging of the anulus in 11 discs, and complete radial fissures in 2 discs, 1 of which allowed posterior migration of nucleus pulposus. Comparisons with the results from tissue culture experiments indicated that the observed changes in matrix compressive stress would inhibit disc cell metabolism throughout the disc, and could lead to progressive deterioration of the matrix. CONCLUSIONS: Minor damage to a vertebral body endplate leads to progressive structural changes in the adjacent intervertebral discs.     

CT辅助山羊腰椎解剖测量及与人体腰椎的对比研究

目的:通过对山羊腰椎的解剖测量以及与人体腰椎的对比研究,为腰椎假体的动物模型建立奠定基础。方法:通过计算机辅助软件Mimics 16.0对波尔山羊新鲜腰椎标本及健康成人腰椎的椎体、椎弓根、椎间盘等部位的解剖参数进行采集,最终运用统计学软件对两者腰椎解剖特点进行对比研究。结果:山羊椎体前高中高后高,最大值分别为(38.7±2.9)、(40.1±2.6)、(40.7±2.7)mm。其终板宽度大于其深度,整体呈心形或肾形外观。山羊上终板向外凸出,下终板凹陷较小,最大值为(1.6±0.6)mm。山羊椎弓根高自L1至L6不断增大,最大值为(30.5±1.9)mm;其椎弓根宽与夹角随着椎体序列的增加先减小后增大,最小值分别为(6.7±0.4)mm与(45.9±2.6)°。山羊椎间盘前高中高后高,三者随着椎间隙的变化数值波动较小;其椎间孔高与宽亦变化较小,分别在(12.9±0.3)~(14.3±1.0)mm与(5.7±1.0)~(6.7±0.9)mm波动。对比结果显示山羊腰椎椎体高、椎弓根高及夹角明显大于人类(P0.05),而其终板宽与深、椎间盘高等明显小于人类(P0.05)。此外,两者某些结构如椎弓根高、椎间盘高等随着椎体序数的增加亦呈现出不同变化规律。结论:山羊腰椎虽然在某些方面如终板及椎间孔形态等与人体存在相似性,但是在诸多方面仍存在较大差异。掌握山羊腰椎的解剖特点及与人体之间的差异对于腰椎假体及相关技术的山羊动物研究具有重要的指导意义。     

椎体终板损伤对兔椎问盘髓核Ⅰ、Ⅱ型胶原的影响

目的 观察椎体终板损伤对兔椎间盘髓核Ⅰ、Ⅱ型胶原的影响并探讨其机制.方法 4个月龄清洁级日本大白兔12只,完整取出40个包含终板的完整椎间盘(L2-L5),随机分为实验组和对照组,每组20个.实验组参考Daniel Haschtmann的方法建立终板损伤模型.椎间盘整体培养2周后,免疫组织化学方法观察椎间盘髓核中Ⅰ、Ⅱ型胶原的表达情况,并用HMIAS-2000图像分析系统进行半定量分析.结果 免疫组织化学染色显示:实验组椎间盘髓核Ⅰ型胶原的表达比对照组高;而Ⅱ型胶原的表达则比对照组低,差异均有统计学意义(P<0.05).结论 外伤致椎体终板损伤后会导致椎间盘髓核Ⅰ、Ⅱ型胶原的变化,继而加速椎间盘退行性变.     

Do we have to pursue complete reduction after PVA in osteoporotic vertebral compression fractures: a finite element analysis

BackgroundConsensus regarding the optimal amount of bone cement and vertebral height in the treatment of osteoporotic vertebral compression fractures (OVCFs) is lacking. Our purpose was to explore the optimal amount of bone cement and vertebral height in OVCF after percutaneous vertebral augmentation (PVA).MethodsA three-dimensional finite element model of the L1-L3 segments was constructed from CT scans of aging osteoporosis patients. Four different postoperative vertebral height models were simulated according to Genant semiquantitative grades 0, 1, 2, and 3. The volume of bone cement filling ranged from 3 ml to 6 ml. These models evaluated the von Mises stress of injured vertebral bodies, adjacent vertebral bodies and intervertebral discs under flexion, extension, left flexion, and right flexion after PVA.ResultsWhen the bone cement content was held constant, as the height of the vertebral body decreased, the stress of the L2 vertebral body decreased during left flexion and right flexion, but the stress of the L2 vertebral body increased and decreased during flexion and extension. As the height of the vertebral body decreased, the stress of the L1-L2 intervertebral disc increased. There was no significant change in the stress of other adjacent vertebrae or intervertebral discs. When the Genant grade was 0, 1, or 2 (3 ml and 4 ml), the stress of the overall vertebral body was closest to normal.ConclusionsWhen the height of the vertebral body is restored to the same height, a bone cement filling volume of 3 ml to 6 ml is suitable and will not produce a significant change in the stress of the vertebral body or adjacent vertebral body. As vertebral body height was lost, it may promote the degeneration of the intervertebral disc above the injury vertebrae after PVA. It is appropriate for the height of the vertebral body to return to Genant grade 0 or Genant grade 1 after surgery. When the height of the vertebral body has Genant grade 2 status, it was best to use 3 ml to 4 ml of bone cement filling. Therefore, when treating OVCFs, clinicians do not need to pursue complete reduction of the vertebral body. It is also important to verify the biomechanics results in clinical studies.     

Changes in vascularity of cartilage endplate of degenerated intervertebral discs in response to melatonin administration in rats

We carried out an experimental investigation of cartilage endplate vascularity of degenerated intervertebral discs produced by exogenous melatonin (MEL) treatment. Adult Swiss albino rats were divided into three groups: control, operated degeneration, and MEL treatment. There were five rats in each group and, using a posterior approach, cuts were made parallel to the endplates in the posterior annulus fibrosus in five consecutive intervertebral discs between the 5th and 10th vertebral segments of the rats' tails. At 8 weeks, five of these animals were treated with exogenous MEL (s.c. injection of 30 μg/100 g body weight daily for 4 weeks). In each experimental group, one animal was examined using CT scanner to study the density of the cartilage endplate of the disc. To evaluate the bone growth and vascularity of the cartilage endplate region, the animals were killed for subsequent histopathological evaluation. We found that the vascular channel counts and percentage areas from animals treated with MEL were significantly lower than from the operated degeneration animals. Accordingly, the density histogram in the MEL group showed a spike profile for both the vertebral body and the cartilage endplate, indicating an increase in the amount of higher density tissues in these regions. Our results demonstrate that the use of MEL reduces the cartilage endplate vascularity of degenerated intervertebral discs, suggesting that it may have an osteoinductive effect on bone formation. Further studies are needed to characterize fully the relevance of our findings for the treatment of disorders such as postmenopausal osteoporosis.