Spinal growth modulation using a novel intravertebral epiphyseal device in an immature porcine model

Purpose  

Fusionless growth modulation is an attractive alternative to conventional treatments of idiopathic scoliosis. To date, fusionless devices achieve unilateral growth modulation by compressing the intervertebral disc. This study explores a device to control spinal alignment and vertebral morphology via growth modulation while excluding the disc in a porcine model.     

Lumbar posterolateral fusion inhibits sensory nerve ingrowth into punctured lumbar intervertebral discs and upregulation of CGRP immunoreactive DRG neuron innervating punctured discs in rats

Degeneration of lumbar intervertebral discs is thought to be a cause of low back pain. Studies have found that a cause of discogenic low back pain is intervertebral disc inflammation and axonal growth of afferent fibers innervating the disc. Lumbar spine fusion for chronic discogenic low back pain is considered an effective procedure. However, no study has investigated the mechanism of pain relief. We did this by applying Fluoro-Gold (FG) to the ventral aspect of the L4–L5 intervertebral discs of 40 rats. We exposed the nucleus pulposus to the annulus fibrosus in a disc punctured model. Rats were divided into 4 groups. Group A: Punctured intervertebral disc with sham posterolateral fusion (PLF) (n = 10), Group B: Punctured intervertebral disc with PLF (n = 15), Group C: Normal intervertebral disc (no puncture) with PLF (n = 10), and Group D: Normal disc (no disc puncture) with sham PLF (n = 5). Four weeks after surgery, bilateral L1–L5 dorsal root ganglia (DRGs) were stained with growth-associated protein 43 (GAP43), a marker of axonal growth, and calcitonin gene-related peptide (CGRP), a neuropeptide marker of pain. Bone union was evaluated using X-ray imaging. Of the FG-labeled neurons, the proportions of GAP43- and CGRP-immunoreactive (IR) neurons in Group A were significantly higher than in Group D (P < 0.05). The proportions of GAP43- and CGRP-IR neurons in bone union rats in Group B were significantly lower than in nonunion rats in Group B and in the rats in Group A (P < 0.05). No significant differences in GAP43- and CGRP-IR neurons were observed between bone union and nonunion rats in Group C and the rats in Group D (P > 0.05). PLF is strongly related to the downregulation of GAP43 and CGRP expression. Therefore, PLF may suppress the increase of inflammatory neuropeptides and the process of axonal growth. Moreover, these results may explain, in part, the mechanism of pain relief following lumbar spinal fusion for chronic discogenic low back pain in humans.     

The changes of relative position of the thoracic aorta after anterior or posterior instrumentation of type I Lenke curve in adolescent idiopathic thoracic scoliosis

The risk of impingement of the aorta associated with thoracic vertebral screw or pedicle screw instrumentation in the treatment of thoracic scoliosis has been an important concern. To understand this phenomenon more systematically, the relative position of the aorta with reference to the thoracic vertebrae in right thoracic adolescent idiopathic scoliosis (AIS) following anterior and posterior spinal instrumentation was analyzed in detail quantitatively; 34 patients underwent anterior (n = 14) or posterior (n = 20) spinal instrumentation were recruited in the present study. The relative position of the thoracic aorta, vertebral rotation, apical vertebral translation and thoracic kyphosis were measured from pre- and post-operative CT images from T5 to T12. The aorta was found to shift antero-medially in the anterior instrumentation group but not in the posterior spinal instrumentation group. It is likely that the disc removal, soft tissue release and spontaneous vertebral derotation of the scoliosis could account for the antero-medial shifting of the aorta. By the shifting, the space for contralateral screw penetration was reduced.     

Spine slenderness and wedging in adolescent idiopathic scoliosis and in asymptomatic population: an observational retrospective study

The origin of the deformity due to adolescent idiopathic scoliosis (AIS) is not known, but mechanical instability of the spine could be involved in its progression. Spine slenderness (the ratio of vertebral height to transversal size) could facilitate this instability, thus playing a role in scoliosis progression. The purpose of this work was to investigate slenderness and wedging of vertebrae and intervertebral discs in AIS patients, relative to their curve topology and to the morphology of control subjects. A total of 321 AIS patients (272 girls, 14 ± 2 years old, median Risser sign 3, Cobb angle 35° ± 18°) and 83 controls were retrospectively included (56 girls, median Risser 2, 14 ± 3 years). Standing biplanar radiography and 3D reconstruction of the spine were performed. Geometrical features were computed: spinal length, vertebral and disc sizes, slenderness ratio, frontal and sagittal wedging angles. Measurement reproducibility was evaluated. AIS girls before 11 years of age had slightly longer spines than controls (p = 0.04, Mann–Whitney test). AIS vertebrae were significantly more slender than controls at almost all levels, almost independently of topology. Frontal wedging of apical vertebrae was higher in AIS, as expected, but also lower junctional discs showed higher wedging than controls. AIS patients showed more slender spines than the asymptomatic population. Analysis of wedging suggests that lower junctional discs and apex vertebra could be locations of mechanical instability. Numerical simulation and longitudinal clinical follow-up of patients could clarify the impact of wedging, slenderness and growth on the biomechanics of scoliosis progression. These slides can be retrieved under Electronic Supplementary Material.     

Intervertebral disc changes with angulation, compression and reduced mobility simulating altered mechanical environment in scoliosis

Purpose  

The intervertebral discs become wedged and narrowed in scoliosis, and this may result from altered biomechanical environment. The effects of four permutations of disc compression, angulation and reduced mobility were studied to identify possible causes of progressive disc deformity in scoliosis. The purpose of this study was to document morphological and biomechanical changes in four different models of altered mechanical environment in intervertebral discs of growing rats and in a sham and control groups.     

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。     

Vertebral column decancellation for the management of sharp angular spinal deformity

The management goal of sharp angular spinal deformity is to realign the spinal deformity and safely decompress the neurological elements. However, some shortcomings related to current osteotomy treatment for these deformities are still evident. We have developed a new spinal osteotomy technique—vertebral column decancellation (VCD), including multilevel vertebral decancellation, removal of residual disc, osteoclasis of the concave cortex, compression of the convex cortex accompanied by posterior instrumentation with pedicle screws, with the expectation to decrease surgical-related complications. From January 2004 to March 2007, 45 patients (27 males/18 females) with severe sharp angular spinal deformities at our institution underwent VCD. The diagnoses included 29 congenital kyphoscoliosis and 16 Pott’s deformity. Preoperative and postoperative radiographic evaluation was performed. Intraoperative, postoperative and general complications were noted. For a kyphosis deformity, an average of 2.2 vertebrae was decancellated (range, 2–4 vertebrae). The mean preoperative kyphosis was +98.6° (range, 82°–138°), and the mean kyphosis in the immediate postoperative period was +16.4° (range, 4°–30°) with an average postoperative correction of +82.2° (range, 61°–124°). For a kyphoscoliosis deformity, the correction rate was 64% in the coronal plane (from 83.4°–30.0°) postoperatively and 32.5° (61% correction) at 2 years’ follow-up. In the sagittal plane, the average preoperative curve of 88.5° was corrected to 28.6° immediately after surgery and to 31.0° at 2 years’ follow-up. All patients had solid fusion at latest follow-up. Complications were encountered in eight patients (17.8%), including CSF leak (n = 1), deep wound infection (n = 1), epidural hematoma (n = 1), transient neurological deficit (n = 4), and complete paralysis (n = 1). The results of this study show that single-stage posterior VCD is an effective option to manage severe sharp angular spinal deformities.     

脊柱结核的MRI表现

目的：探讨MRI对脊柱结核的诊断价值。方法：回顾分析98例经手术病理证实的脊柱结核患者的脊柱MRI征象，观察椎体、终板、椎间盘及椎管等变化，并与X线平片及CT片进行比较。结果：椎体结核早期．MRI上可见椎体形态正常，椎体前中部骨质破坏，呈片状长T1、长T2信号影，边界不清；椎体终板局限性破坏．椎间盘信号不均匀，可见囊状小脓肿形成；椎旁软组织肿胀或少量脓肿形成。MRI对椎体破坏、椎间盘受累、椎旁脓肿及椎管受累的诊断优于X线平片及CT（P〈0．05）。结论：MRI对病变椎体病理改变具有高敏感性，使脊柱结核的早期诊断成为可能。MRI可清晰最示脊柱结核的椎体骨炎、椎旁脓肿、终板破坏及受累椎管狭窄程度．并有助于与椎体肿瘤的鉴别。     

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

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

Influence of asymmetric tether on the macroscopic permeability of the vertebral end plate

We implemented an experimental model of asymmetrical compression loading of the vertebral end plate (VEP) in vivo. The macroscopic permeability of the VEP was measured. We hypothesized that static asymmetrical loading on vertebrae altered the macroscopic permeability of the VEP. In scoliosis, solute transport to and from the disc is dramatically decreased especially at the apical intervertebral disc. The decrease in permeability could be induced by mechanical stress. Nine skeletally immature pigs were instrumented with left pedicle screws and compression rod at the T5/T6 and L1/L2 levels. After 3 months, three cylindrical specimens of the VEP were obtained from each of the tethered levels. A previously validated method for measuring permeability, based on the relaxation pressure due to a transient-flow rate was used. A pistoning device generated a fluid flow that fully saturated the cylindrical specimen. The decrease in upstream pressure was measured using a pressure transducer, which allowed the macroscopic permeability to be derived. A microscopic study completed the approach. Overall macroscopic permeability was lower for the tethered VEPs than for the VEPs of the control group, respectively −47% for flow-in (p = 0.0001) and −46% for flow-out (p = 0.0001). In the tethered group, macroscopic permeability of the specimens from the tethered side was lower than macroscopic permeability of those from the non-tethered side, −39% for flow-out (p = 0.024) and −47% for flow-in (p = 0.13). In the control group, the macroscopic permeability was greater in the center of the VEP than in its lateral parts for flow-out (p = 0.004). Macroscopic permeability of the center of the VEPs was greater for flow-out than for flow-in (p = 0.02). There was no significant difference between thoracic and lumbar. This study demonstrated that compression loading applied to a growing spine results in decreased permeability of the VEP. This result could be explained by local remodeling, such as calcification of the cartilage end plate or sclerosis of the underlying bone.     

Imaging study of wedge changes in the vertebral bodies and intervertebral discs in adolescent idiopathic scoliosis

Objective: To observe wedge changes in the vertebral bodies and intervertebral discs in progressive adolescent idiopathic scoliosis before and after conservative treatment with braces, and to explore the correlation between wedge changes in the vertebral bodies or intervertebral discs and scoliosis curves. Methods: Thirty‐seven consecutive patients with adolescent idiopathic scoliosis were included in this study from June 2001 to August 2003. There were 31 female and 6 male patients, with an average age of 14.9 years. According to the Peking Union Medical College (PUMC) grading system, eight cases were Ia, three Ib, five Ic, twelve IIb1, three IIb2, three IIc1, one IIc3, and two IId1. Wedge changes in the vertebral bodies and intervertebral discs, and the scoliosis angles were measured by radiographic evaluation before conservative treatment with braces and before surgery. Results: In the mature patients (Risser sign IV, V, menarche two years or more previously), wedge changes in the vertebral bodies and intervertebral discs worsened with curve progression, and were poorly correlated with the degree of curve (r= 0.17). But in the developmentally immature patients (Risser sign 0–III, pre‐menarche), there was a significant correlation with the degree of curve (r= 0.69). Wedge changes in the vertebral bodies and intervertebral discs worsened with curve progression, and were significantly correlated with the degree of curve. Conclusion: Wedge changes in the vertebral bodies and intervertebral discs have a positive correlation with degree of curve, which indicates that asymmetric growth of the cartilaginous endplate might be the primary cause of wedge change in the vertebral bodies.     

退变性腰椎侧凸形成和发展的相关因素分析

目的 探讨退变性腰椎侧凸患者椎问盘的不对称指数、腰椎间盘退变程度以及骨密度降低对侧凸角度的影响.方法 采用回顾性研究的方法,选取2002年1月至2010年8月,共96例退变性腰椎侧凸患者为研究对象(侧凸组);2002年1月至2010年8月确诊为腰椎管狭窄症并且资料齐全的患者96例为对照组;两组间性别、年龄、体质量指数匹配.侧凸组:在腰椎正位X线片上测量凸凹侧顶椎间盘及其上下椎间盘的高度和顶椎及其上下椎体的高度,利用Adobe Photoshop 6.0软件,测量MRI图像T2WI顶椎及其上下椎间盘内髓核与脑脊液的相对信号强度.对照组:取2～3、L3-4、L4-5这3个椎间盘为研究对象测定上述指标.应用双能X线吸收法测定两组患者腰椎(L2-4)及股骨颈、股骨粗隆和Ward's三角的T值.结果 侧凸组凸侧椎间盘高度和为(40±7)mm高于凹侧的(28±7)mm(P<0.01),凸侧椎体高度和为(76±12)mm高于凹侧的(72±10)mm(P=0.016):两组之间的椎间盘退变程度差异有统计学差异(P=0.003);两组之间骨密度T值的平均值和骨质疏松的发生率差异有统计学意义(均P<0.01).通过多元线性回归分析结果 显示患者椎间盘的不对称指数、椎间盘的退变程度、骨密度T值影响退变性腰椎侧凸角度.结论 退变性腰椎侧凸常伴有凸凹两侧椎间盘高度以及椎体高度不对称.侧凸角度与椎间盘的不对称指数、椎间盘的退变程度呈正相关,与骨密度值T值呈负相关.

Abstract：

Objectives To investigate the correlation between scoliosis angle and the asymmetric index of degenerative lumbar scoliosis, the degree of intervertebral disc degeneration, decreased bone density. Methods As a retrospectively study, a total of 96 patients with degenerative lumbar scoliosis were retrospectively enrolled from January 2002 to August 2010 as scoliosis group, meanwhile % patients with lumbar spinal stenosis matched in gender, age and body mass index (BMI) were selected as control group.All patients were studied with plain radiographs, MRI and dual energy X-ray absorptiometry at presentation. Radiographic measurements include Cobb angle, the height of the convex and concave side of the apical disc and the contiguous disc superiorly and inferiorly, the height of the convex and concave side of the apical and the contiguous vertebral body superiorly and inferiorly in scoliosis group, the height of L2-3, L3-4, L4-5 discs and the height of L2-4 vertebral body in control group. The average relative signal intensity of lumbar intervertebral disc and cerebrospinal fluid in T2WI sagittal image was measured in apex intervertebral disc and adjacent discs by Adobe Photoshop 6.0 in scoliosis group, which was measured in L2-3, L3-4, L4-5 disc in control group. The bone density of lumbar, femoral neck, trochanter, and Ward's triangle regions were measured with dual-energy X-ray absorptiometry. Results The intervertebral disc height in convex side was greater than the height in the concave side [(40 ± 7) mm vs. (28 ± 7) mm, P < 0. 01] , the vertebral body height in convex side was greater than the height in the concave side [(76 ± 12) mm vs. (72 ± 10) mm, P =0.016] in scoliosis group. There was significant statistically difference in the degenerative degree of intervertebral discs between two groups (P = 0. 003). There was significant statistically difference of the average T-value and the rate of osteoporosis between two groups (P < 0. 01). Multiple linear regression analysis showed that the asymmetric disc index, the degenerative degree of intervertebral disc and osteoporosis were the predominant correlative factors, which affected the development of degenerative lumbar scoliosis. Conclusions Degenerative lumbar scoliosis is always accompanied by the height asymmetry of intervertebral discs and vertebral body from convex and concavity sides. There is positive correlation between the angle of scoliosis and the asymmetric disc index, the degeneration of intervertebral disc, and negative correlation between the angle of scoliosis and the bone density (T-value).     

Pinealectomy in the chicken: a good model of scoliosis?

The phenomenon of spinal deformity in the pinealectomized chicken has led researchers to postulate a disturbance of melatonin activity as a potential cause of adolescent idiopathic scoliosis (AIS). More recently, structural differences between curves seen in this model and those seen in scoliosis have been highlighted suggesting the deformities observed are not as similar as first thought. We examined melatonin levels, and the radiological and histological characteristics of scoliosis after pinealectomy in chickens. They underwent pinealectomy (P) at 2 days of age, sham surgery (S) or served as controls (C). Mean melatonin levels were 32.9 pmol/L (P), 175 pmol/L (S) and 227.3 pmol/L (C). Scoliosis developed in 75% of chickens after pinealectomy and 38% after a sham procedure. Nineteen percent of unoperated controls also developed scoliosis. A lower melatonin level was associated with the development of scoliosis (p ≤ 0.001), but exceptions were seen with levels up to 265 pmol/L observed in one case. Most of the curves occurring spontaneously and after sham surgery and almost half after pinealectomy were short angular curves: distinct from those resembling idiopathic scoliosis. These occur over one or two segments and are characterized by marked apical wedging, frequently associated with subluxation or dislocation. The intervertebral joint in the chicken is more like a synovial joint histologically than an intervertebral disc. This study highlights important differences between the chicken and the human, and between their respective spinal deformities. Caution is advised when drawing conclusions regarding the pathogenesis of AIS from this model.     

The modulation of spinal growth with nitinol intervertebral stapling in an established swine model

Purpose

Anterior spinal stapling for the treatment of adolescent idiopathic scoliosis has been shown to slow progression in small curves; however, its role in larger curves remains unclear. The purpose of this study was to evaluate the effectiveness of nitinol staples to modulate spinal growth by evaluating the two-dimensional and three-dimensional morphological and histological effects of this method in a well-established porcine model.

Methods

Three immature Yucatan miniature pigs underwent intervertebral stapling. Two staples spanned each of three consecutive mid-thoracic discs and epiphyses. Monthly radiographs were obtained. Computed tomography (CT) was conducted at harvest after 6 months of growth. Measurements of wedging and height for each disc and vertebral body were conducted. Micro CT was used to compare physeal closure between stapled and non-stapled levels. Histology of the growth plate also compared the hypertrophic zone thickness for control and stapled vertebrae.

Results

After 6 months of stapled growth, the average coronal Cobb angle of the stapled segments increased by 7.7 ± 2.0° and kyphosis increased by 3.3 ± 0.6° compared to preoperative curves. Increased vertebral wedging and decreased disc height (p < 0.001) were noted in stapled regions. Overall, 26 ± 23 % of each growth plate was closed in the stapled segments, with 6 ± 8 % closure in the unstapled levels. No difference was observed regarding the hypertrophic zone height when comparing instrumented to uninstrumented levels, nor was a difference recognized when comparing right versus left regions within stapled levels alone.

Conclusions

Six months of nitinol intervertebral stapling created a mild coronal and sagittal deformity associated with reduced vertebral and disc height, and increased coronal vertebral and sagittal disc wedging.     

国人颈椎椎间盘解剖参数与常用人工椎间盘尺寸的比较

目的　分析临床上常用的人工椎间盘尺寸是否与国人颈椎椎体解剖尺寸相匹配,并据此提出适合国人的人工颈椎椎间盘设计方案。方法利用CT测量138例国内患者C_(2～7)椎体的相关解剖学数据(椎体终板前后径、横径,椎间隙高度,矢状角大小),并分别与4种常用人工椎间盘(Bryan、Prestige LP、Discover、Prodisc-C)的尺寸进行比较,分析人工椎间盘的尺寸是否与各个椎间隙尺寸相匹配,并计算不匹配率。结果 4种常用人工椎间盘中,在椎体终板前后径上与国人颈椎椎体解剖尺寸的不匹配率为15.22%(C_3/C_4节段,Prestige LP、Prodisc-C)至57.61%(C_6/C_7节段,Discover);在横径上的不匹配率为24.28%(C_3/C_4节段,Prodisc-C、Prestige LP)至94.93%(C_6/C_7节段,Bryan)。所有患者中,19.71%的椎体终板前后径大于最大人工椎间盘,52.17%的椎体终板最大横径大于最大人工椎间盘。除了因高度不固定而无法比较的Bryan人工椎间盘,其他人工椎间盘的最大高度均满足患者各节段的最大椎间隙高度,但39.13%的颈椎椎间隙高度小于最小的人工椎间盘高度。C_2/C_3、C_3/C_4、C_4/C_5、C_5/C_6、C_6/C_7节段平均矢状角分别为3.64°、4.51°、5.04°、5.15°、4.13°,纳入的4种人工椎间盘中只有Discover有固定的7°前凸角与之相符。结论目前临床上常用的人工椎间盘尺寸与国人椎体解剖数据存在较大差异,应设计更多的人工椎间盘尺寸来匹配国人颈椎。     

Disc degeneration of cervical spine on MRI in patients with lumbar disc herniation: comparison study with asymptomatic volunteers

An association between progression of cervical disc degeneration and that of lumbar disc degeneration has been considered to exist. To date, however, this association has not yet been adequately studied. Age-related changes in the cervical intervertebral discs were evaluated by magnetic resonance imaging (MRI) in patients with lumbar disc herniation, and compared with the MRI findings of healthy volunteers without lower back pain. The purpose of this study was to clarify whether the prevalence of asymptomatic cervical disc degeneration is higher in patients with lumbar disc herniation than in healthy volunteers. The study was conducted on 51 patients who were diagnosed as having lumbar disc herniation and underwent cervical spine MRI. The patients consisted of 34 males and 17 females ranging in age from 21–83 years (mean 46.9 ± 14.5 years) at the time of the study. The control group was composed of 113 healthy volunteers (70 males and 43 females) aged 24–77 years (mean 48.9 ± 14.7 years), without neck pain or low back pain. The percentage of subjects with degenerative changes in the cervical discs was 98.0% in the lumbar disc herniation group and 88.5% in the control group (p = 0.034). The presence of lumbar disc herniation was associated significantly with decrease in signal intensity of intervertebral disc and posterior disc protrusion in the cervical spine. None of the MRI findings was significantly associated with the gender, smoking, sports activities, or BMI. As compared to healthy volunteers, patients with lumbar disc herniation showed a higher prevalence of decrease in signal intensity of intervertebral disc and posterior disc protrusion on MRI of the cervical spine. The result of this study suggests that disc degeneration appears to be a systemic phenomenon.     

Static and dynamic compression application and removal on the intervertebral discs of growing rats

Fusionless implants are used to correct pediatric progressive spinal deformities, most of them spanning the intervertebral disc. This study aimed at investigating the effects of in vivo static versus dynamic compression application and removal on discs of growing rats. A microloading device applied compression. 48 immature rats (28 d.o.) were divided into two groups (43d, 53d). Each group included four subgroups: control (no surgery), sham (device installed without loading), static (0.2 MPa) and dynamic compressions (0.2 MPa ± 30% with 0.1 Hz). In 43d subgroups, compression was applied for 15 days. In 53d subgroups, compression was followed by 10 days without loading. Disc heights, nucleus/annulus volumetric proportions and nucleus proteoglycan contents were analyzed using one‐way ANOVA and post‐hoc Tukey comparisons (p < 0.05). Disc heights of 43d and 53d static and dynamic loading rats were lower than shams (p < 0.05). Volumetric proportions remained similar. At 43d, nucleus proteoglycan contents increased in both static and dynamic loading rats. However, at 53d, static loading rats had lower proteoglycan content than dynamic loading rats (p < 0.05). Disc structure is altered following static compression removal, but nucleus proteoglycan content remaining elevated in dynamic group. Dynamic fusionless implants would better preserve disc integrity. © 2015 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 34:290–298, 2016.     

Disc and vertebral wedging in patients with progressive scoliosis

A retrospective longitudinal radiographic study of patients with progressive scoliosis was conducted to determine the relative amount of wedging between vertebrae and discs as a function of progression of the scoliosis curve, cause of the scoliosis, and anatomic curve region. Posteroanterior radiographs of 27 patients with idiopathic scoliosis and of 17 patients with scoliosis associated with cerebral palsy were studied. The amount of wedging of vertebrae and discs at the curve apex was measured by the Cobb method and expressed as a proportion of the curve's Cobb angle. On average, the relative amount of vertebral and disc wedging did not differ significantly between initial and follow-up radiographs made after progression of the scoliosis. In both groups of patients, the mean vertebral wedging was more than the disc wedging in the thoracic region; the converse was found in curves in the lumbar and thoracolumbar regions. The patients with scoliosis associated with cerebral palsy had curves that were longer and more commonly in the thoracolumbar and lumbar regions. The relative wedging did not change significantly with curve progression and did not appear to differ by diagnosis. In the management of scoliosis, including small curves, it should be recognized that both the vertebrae and discs have a wedging deformity.     

Anterior lengthening in scoliosis occurs only in the disc and is similar in different types of scoliosis

BACKGROUND CONTEXTRelative anterior spinal overgrowth was proposed as a generalized growth disturbance and a potential initiator of adolescent idiopathic scoliosis (AIS). However, anterior lengthening has also been observed in neuromuscular (NM) scoliosis and was shown to be restricted to the apical areas and located in the intervertebral discs, not in the bone. This suggests that relative anterior spinal overgrowth does not rightfully describe anterior lengthening in scoliosis, as it seems not a generalized active growth phenomenon, nor specific to AIS.PURPOSETo determine if compensatory curves in congenital scoliosis exhibit a mechanism of anterior lengthening without changes in the vertebral body, similar to curves in AIS and NM scoliosis.STUDY DESIGN/SETTINGCross-sectional.PATIENT SAMPLECT-scans were included of patients in whom a short segment congenital malformation had led to a long thoracic compensatory curve without bony abnormality. Based on data of other scoliosis types, the calculated required sample size was n=12 to detect equivalence of vertebral bodies as compared with nonscoliotic controls. Out of 143 congenital scoliosis patients, 18 fit the criteria and compared with 30 nonscoliotic controls, 30 AIS and 30 NM scoliosis patients.OUTCOME MEASURESThe anterior-posterior length discrepancy (AP%) of the total curve and for vertebral bodies and intervertebral discs separately.METHODSOf each vertebral body and intervertebral disc in the compensatory curve, the anterior and posterior length was measured on CT-scans in the exact mid-sagittal plane, corrected for deformity in all three planes. The AP% was calculated for the total compensatory curve (Cobb-to-Cobb) and for the vertebral bodies and the intervertebral discs separately. Positive AP% indicated that the anterior side was longer than the posterior side.RESULTSThe total AP% of the compensatory curve in congenital scoliosis showed lordosis (+1.8%) that differed from the kyphosis in nonscoliotic controls (−3.0%; p<.001) and was comparable to the major curve in AIS (+1.2%) and NM scoliosis (+0.5%). This anterior lengthening was not located in the bone; the vertebral body AP% showed kyphosis (−3.2%), similar to nonscoliotic controls (−3.4%) as well as AIS (−2.5%) and NM scoliosis (−4.5%; p=1.000). However, the disc AP% showed lordosis (+24.3%), which sharply contrasts to the kyphotic discs of controls (−1.5%; p<.001), but was similar to AIS (+17.5%) and NM scoliosis (+20.5%).CONCLUSIONSThe current study on compensatory curves in congenital scoliosis confirms that anterior lengthening is part of the three-dimensional deformity in different types of scoliosis and is exclusively located in the intervertebral discs. The bony vertebral bodies maintain their kyphotic shape, which indicates that there is no active anterior bony overgrowth. Anterior lengthening appears to be a passive result of any scoliotic deformity, rather than being related to the specific cause of AIS.     

椎体和椎间盘矢状面形态学改变对退变性脊柱后凸畸形的影响

目的：探讨椎体楔形变和椎间盘退变（塌陷）等形态学改变对成人退变性胸腰椎/腰椎后凸畸形的影响。方法：回顾性分析2015年8月至2020年12月收治的32例脊柱退变性胸腰椎/腰椎后凸畸形患者,其中男8例,女24例,年龄48~75（60.3±12.4）岁。在站立位全脊柱正侧位X线片上测量脊柱冠状面侧凸Cobb角和矢状面胸腰椎/腰椎后凸角（kyphosis angle,KA）,评估顶椎（apex vertebral,AV）及顶椎上下各2个椎体（AV-1,AV-2,AV+1,AV+2）与椎间盘（AV-1D,AV-2D,AV+1D,AV+2D）的高度及楔变参数,包括椎体前缘高度（anterior vertebral body height,AVH）,椎体后缘高度（posterior vertebral body height,PVH）,椎体楔变角（vertebral wedge angle,VWA）,椎体楔变率（ratio of vertebral wedging,RVW）;椎间盘前缘高度（anterior disc height,ADH）,椎间盘后缘高度（posterior disc height,PDH）,椎间盘楔变角（disc wedge angle,DWA）,椎间盘楔变率（ratio of disc wedging,RDW）,椎间盘贡献率（DWA/KA）。结果：所纳入患者KA为（44.2±19.1）°,后凸节段内椎体前缘高度均显著低于椎体后缘高度（P<0.05）,提示椎体发生不同程度楔形变;而后凸节段内椎间盘前后缘高度差异无统计学意义。后凸节段内椎体楔变率/贡献率分别为AV-2（14.98±10.95）%/（14.21±8.08）%,AV-1（21.08±12.39）%/（18.09±7.38）%,AV （26.94±11.94）%/（25.52±8.64）%,AV+1（24.19±8.42）%/（20.82±8.69）%,AV+2（20.56±7.80）%/（15.60±9.71）%,椎体总贡献率为（94.23±22.25）%;后凸节段内椎间盘楔变率/贡献率分别为AV-2D （2.88±2.57）%/（5.27±4.11）%,AV-1D （1.98±1.41）%/（2.29±2.16）%,AV+1D （-5.54±3.75）%/（-0.57±0.46）%,AV+2D （-8.27±4.62）%/（-1.22±1.11）%,椎间盘总贡献率（5.77±4.79）%,且顶椎贡献率明显大于邻近椎体贡献率（P<0.05）。结论：椎体楔形变及椎间盘塌陷共同构成了成人退变性胸腰椎/腰椎后凸畸形状态。就对后凸贡献率而言,椎体形态改变对后凸的贡献要远超椎间盘的贡献,且顶椎的楔形变对胸腰椎/腰椎后凸的贡献尤为明显。