Analysis of vertebral morphology in idiopathic scoliosis with use of magnetic resonance imaging and multiplanar reconstruction

BACKGROUND: Several studies have provided data on the vertebral morphology of normal spines, but there is a paucity of data on the vertebral morphology in patients with idiopathic scoliosis. METHODS: The morphology of the pedicles and bodies of 307 vertebrae as well as the distance between the pedicles and the dural sac (the epidural space) in twenty-six patients with right-sided thoracic idiopathic scoliosis were analyzed with use of magnetic resonance imaging and multiplanar reconstruction. RESULTS: A distinct vertebral asymmetry was found at the apical region of the thoracic curves, with significantly thinner pedicles on the concave side than on the convex side (p < 0.05). The degree of intravertebral deformity diminished farther away from the apex, with vertebral symmetry restored at the neutral level. In the thoracic spine, the transverse endosteal width of the apical pedicles measured between 2.3 mm and 3.2 mm on the concave side and between 3.9 mm and 4.4 mm on the convex side (p < 0.05). In the lumbar spine, the pedicle width measured between 4.6 mm at the cephalad part of the curve and 7.9 mm at the caudad part of the curve. The chord length and the pedicle length gradually increased from 34 mm and 18 mm, respectively, at the fourth thoracic vertebra to 51 mm and 25 mm, respectively, at the third lumbar vertebra. The transverse pedicle angle measured 15 in the cephalad aspect of the thoracic spine, decreased to 7 at the twelfth thoracic vertebra, and increased again to 16 at the fourth lumbar vertebra. The width of the epidural space was <1 mm at the thoracic apical vertebral levels and averaged 1 mm at the lumbar apical vertebral levels on the concave side, whereas it was between 3 mm and 5 mm on the convex side (p < 0.05). CONCLUSION: Idiopathic scoliosis is associated with distinctive intravertebral deformity, with smaller pedicles on the concave side and a shift of the dural sac toward the concavity.     

特发性胸椎侧凸前路矫形对胸主动脉偏移的影响及意义

目的 比较青少年特发性胸椎右侧凸患者前路开放小切口矫形手术和后路矫形手术对胸主动脉偏移的影响及其意义.方法 29例青少年特发性胸椎右侧凸患者分为两组.A组14例患者行开放小切口前路矫形术,男1例,女13例,平均14.3岁,胸弯Cobb角平均44.9°.B组15例患者行后路钉钩联合矫形术,男3例,女12例,平均14.2岁,胸弯Cobb角平均46.4°.两组患者手术前后均行胸椎T5～T12节段CT扫描,在每个节段测量右侧肋骨头至主动脉后壁的切线与双侧肋骨头连线的夹角(α)、椎管前缘中点与主动脉中心连线和双侧肋骨头连线的夹角(β)、椎体旋转(γ)、主动脉与椎体间距离(a)以及与左侧肋骨头前缘的垂直距离(b)并进行比较.将胸主动脉偏移与侧凸的三维矫形进行相关性分析明确胸主动脉偏移的原因.结果 A组患者手术后置钉安全角α、主动脉相对椎管前缘旋转角β较术前增大,在T8,T9差异有显著性(P＜0.05);椎体旋转γ角减小,在T8,T9差异有显著性(P＜0.05);主动脉与椎体间距离a减小,主动脉后壁与右侧肋骨头间距离b增大,两者和术前相比在T9有显著性差异(P＜0.05).B组手术前后椎体旋转及主动脉与相邻椎体的解剖关系无明显变化.A组α角、β角、b值增加量与γ角减小量呈明显相关性(P＜0.01);a值减少量与β角增加量具有良好相关性(P＜0.05);在顶椎区α角、β角、b值的增加量与顶椎偏移减少量、a值减少量与T5～T12后凸增加量明显相关(P＜0.01).结论 特发性胸椎右侧凸患者行小切口前路矫形术后胸主动脉相对椎体向前方偏移并靠近椎体.发生主动脉偏移的原因包括主动脉松解、椎体去旋转、冠状面和矢状面矫形.     

青少年特发性脊柱侧凸胸廓对椎体轴向旋转影响的力学研究

目的 研究青少年特发性脊柱侧凸(AIS)在轴向负载条件下胸廓结构对椎体旋转的影响.方法 基于AIS患者CT扫描数据,构建包括胸廓和不包括胸廓两种三维有限元模型,进入ANSYS前处理器,设置边界条件和载荷,进入求解模块,进行不同载荷下轴向负载模拟计算,最后进入ANSYS后处理器,读取并分析脊柱侧凸不同椎体旋转角度大小和方向变化.结果 胸廓对胸椎结构性侧凸以上椎体的旋转角度大小和旋转方向有明确影响,对腰椎椎体和骶椎的旋转没有作用.胸廓对顶椎的轴向旋转角度仅有轻度影响,两种模型在不同载荷条件下,顶椎的旋转方向一致,角度大小比较差异无统计学意义.结论 AIS脊柱畸形造成椎体和胸廓结构的解剖学改变,会带来生物力学的相应改变.畸形的胸廓不能有效保护胸椎轴向旋转的稳定性.     

Differences in early sagittal plane alignment between thoracic and lumbar adolescent idiopathic scoliosis

Background contextIt has previously been shown that rotational stability of spinal segments is reduced by posteriorly directed shear loads that are the result of gravity and muscle tone. Posterior shear loads act on those segments of the spine that are posteriorly inclined, as determined by each individual's inherited sagittal spinal profile. Accordingly, it can be inferred that certain sagittal spinal profiles are more prone to develop a rotational deformity that may lead to idiopathic scoliosis; and lumbar scoliosis, on one end of the spectrum, develops from a different sagittal spinal profile than thoracic scoliosis on the other end.PurposeTo examine the role of sagittal spinopelvic alignment in the etiopathogenesis of different types of idiopathic scoliosis.Study design/settingMulticenter retrospective analysis of lateral radiographs of patients with small thoracic and lumbar adolescent idiopathic scoliotic curves.Patients sampleWe included 192 adolescent idiopathic scoliosis patients with either a thoracic (n=128) or lumbar (n=64) structural curve with a Cobb angle of less than 20° were studied. Children with other spinal pathology or with more severe idiopathic scoliosis were excluded, because this disturbs their original sagittal profile. Subjects who underwent scoliosis screening and had a normal spine were included in the control cohort (n=95).Outcome measuresThoracic kyphosis, lumbar lordosis, T9 sagittal offset, C7 and T4 sagittal plumb lines, pelvic incidence, pelvic tilt, and sacral slope, as well as parameters describing orientation in space of each individual vertebra between C7 and L5 and length of the posteriorly inclined segment.MethodsOn standardized lateral radiographs of the spine, a systematic, semi-automatic measurement of the different sagittal spinopelvic parameters was performed for each subject using in-house developed computer software.ResultsEarly thoracic scoliosis showed a significantly different sagittal plane from lumbar scoliosis. Furthermore, both scoliotic curve patterns were different from controls, but in a different sense. Thoracic kyphosis was significantly decreased in thoracic scoliosis compared with both lumbar scoliosis patients and controls. For thoracic scoliosis, a significantly longer posteriorly inclined segment, and steeper posterior inclination of C7–T8 was observed compared with both lumbar scoliosis and controls. In lumbar scoliosis, the posteriorly inclined segment was shorter and located lower in the spine, and T12–L4 was more posteriorly inclined than in the thoracic group. The lumbar scoliosis cohort had a posteriorly inclined segment of the same length as controls, but T12–L2 showed steeper posterior inclination. Lumbar lordosis, pelvic incidence, pelvic tilt, and sacral slope, however, were similar for the two scoliotic subgroups as well as the controls.ConclusionsThis study demonstrates that even at an early stage in the condition, the sagittal profile of thoracic adolescent idiopathic scoliosis differs significantly from lumbar scoliosis, and both types of scoliosis differ from controls, but in different aspects. This supports the theory that differences in underlying sagittal profile play a role in the development of different types of idiopathic scoliosis.     

Structural vertebral changes in the horizontal plane in idiopathic scoliosis and the long-term corrective effect of spine instrumentation

Summary The rotation and structural changes of the apex vertebra in the horizontal plane as well as of the thoracic cage deformity were quantified by measurements on computed tomography (CT) scans from patients with right convex thoracic idiopathic scoliosis (IS). The CT scans were obtained from 12 patients with moderate scoliosis (mean Cobb angle 25.8°, r 13°–30°) and from 33 with severe scoliosis (mean Cobb angle 46.2°, r 35°–71°). In addition, CT scans of thoracic vertebrae from 15 patients without scoliosis were used as reference material. Ten of the scoliotic cases had had Cotrel-Dubousset instrumentation (CDI) and posterior fusion and had entered a longitudinal study on the effect of operative correction on the re-modelling of the apical vertebra. An increasingly asymmetrical vertebral body, transverse process angle, pedicle width and canal width were found in the groups with scoliosis as compared with the reference material. Vertebral rotation and rib hump index were significantly larger in patients with early and advanced scoliosis than in normal subjects. The modelling angle of the vertebral body, the transverse process angle index and the vertebral rotation in relation to the middle axis of the thoracic cage were significantly greater in patients with severe than with moderate scoliosis. The results of this longitudinal study suggest that the structural changes of the apical vertebra regress 2 years or more after CD instrumentation.     

Morphometric analysis of thoracic and lumbar vertebrae in idiopathic scoliosis

STUDY DESIGN: Prospective study on the morphometry of 337 pedicles in 29 patients with idiopathic scoliosis. OBJECTIVES: To analyze by means of computed tomographic scans the vertebral morphometry in idiopathic scoliosis treated by pedicle screw instrumentation. SUMMARY OF BACKGROUND DATA: Although several studies exist on the vertebrae's morphometry in normal spines, little is known concerning the morphometry of scoliotic vertebrae. METHODS: The pedicles' morphometry between T5 and L4 was analyzed by computed tomographic scans in 29 surgically treated patients with idiopathic right thoracic scoliosis. Measurements included chord length, endosteal transverse pedicle width, transverse pedicle angle, and pedicle length. RESULTS: The endosteal transverse pedicle width was significantly smaller (P < 0.05) on the concavity in the apical region of the thoracic spine and measured between 2.5 and 4.2 mm in the middle thoracic spine (T5-T9) and between 4.2 and 5.9 mm in the lower thoracic spine (T10-T12). In the lumbar spine, the width varied between 4.8 and 9.5 mm without significant differences between the concave and convex sides (P > 0.05). The chord length was shortest at T5, measuring 37 mm and increased gradually to 50 mm at L3 with significantly larger dimensions in male patients and on the concavity of the apical region in the thoracic spine (P < 0.05). The pedicle length varied minimally, with a range of between 20 and 22 mm, and was relatively consistent throughout the thoracic and lumbar spine. The transverse pedicle angle varied between 6 degrees in the lower thoracic spine and 12 degrees in the upper thoracic and lower lumbar spine. CONCLUSION: The morphometry in scoliotic vertebrae is substantially different from that of vertebrae in normal spines, with an asymmetrical intravertebral deformity shown in scoliotic vertebrae. Pedicle screw instrumentation on the concavity in the apical region of thoracic curves appears critical because of the small endosteal pedicle width.     

Placement of pedicle screws in thoracic idiopathic scoliosis: a magnetic resonance imaging analysis of screw placement relative to structures at risk

In posterior pedicle screw instrumentation of thoracic idiopathic scoliosis, screw malposition might cause significant morbidity in tems of possible pleural, spinal cord, and aorta injury. Preoperative axial magnetic resonace images (MRI) in 12 consecutive patients with right thoracic adolescent scoliosis, all with King type 3 curves, were analyzed in order to evaluate the relationship between the inserted pedicle screw position to pleura, spinal cord, aorta. Axial vertebral images for each thoracic level were scanned and the simulation of pedicle screw insertion was performed using a digital measurement programme. The angular contact value for each parameter regarding the pleura and spinal cord was measured on both sides of the curve. The aorta-vertebral distance was also measured. Aorta-vertebral distance was found to be decreasing gradually from the cephalad to the caudad with the shortest distance being measured at T12 with a mean of 1.2 mm. Concave-sided screws on T5–T9 and convex-sided screws on T2–T3 had the greatest risk to spinal cord injury. Pleural injury is most likely on T4–T9 segments by the convex side screws. T4–T8 screws on the concave side and T11–T12 screws on the convex side may pose risk to the aorta. This MRI-based study demonstrated that in pedicle instrumentation of thoracic levels, every segment deserves special consideration, where computer scanning might be mandatory in immature spine and in patients with severe deformity.     

脊柱侧凸患者胸主动脉与相邻椎体的解剖关系及临床意义

目的:观察胸椎侧凸患者胸主动脉与相邻椎体的解剖关系,并探讨其临床意义。方法:30例胸椎侧凸患者行胸椎CT平扫,测量T4～T12椎体横断面上右侧肋骨小头至主动脉后壁的切线与双侧肋骨小头连线(线RR)的夹角(α)、椎管前缘中点至主动脉中点连线与线RR的夹角(β)、线RR至椎管前壁的垂直距离(a)、左侧肋骨小头前缘至主动脉后壁的距离(b)、椎体横径(c)及椎体旋转角(γ),并与64例无脊柱畸形者对比。结果:从T4～T12,两组的α角、β角和b值均存在先减小后增大的趋势,脊柱侧凸组均较对照组低,且α角在T7～T10、β角在T5～T10和b值在T9、T10显著低于正常对照组。从T4～T12,两组的a值均逐渐降低,且脊柱侧凸组显著低于对照组。两组的c值从T4～T12均逐渐增加,两组间差异无统计学意义。结论:胸椎侧凸患者术前行影像学检查测量胸主动脉与相邻椎体上述指标,可更精确、更安全地放置螺钉。     

The anatomical relationship between the aorta and the thoracic vertebral bodies and its importance in the placement of the screw in thoracoscopic correction of Scoliosis

Thoracoscopically-assisted anterior spinal instrumentation is being used widely to treat adolescent idiopathic scoliosis (AIS). Recent studies have showed that screws placed thoracoscopically could counter the aorta or entrance into the spinal canal. There are a few studies defining the anatomic landmarks to identify the relationship between the aorta and the thoracic vertebral body using quantitative measurement for the sake of safe placement of thoracoscopic vertebral screw in anterior correction for AIS. The CT scanning from T4 to T12 in 64 control subjects and 30 AIS patients from mainland China were analyzed manually. Parameters to be measured included the angle for safety screw placement (α), the angle of the aorta relative to the vertebral body (β), the distance from the line between the left and the right rib heads to the anterior wall of the vertebral canal (a), the distance from the left rib head to posterior wall of the aorta (b), the vertebral body transverse diameter (c) and vertebral rotation (γ). No significant differences were found between the groups with respect to age or sex. Compared with the control group, α angle from T7 to T10, β angle from T5 to T10 and b value at T9, T10 were significantly lower in the scoliotic group. The a value was significantly lower in the scoliotic group. The c value showed no significant difference between the two groups. In conclusion, to place the thoracoscopic vertebral screw safely, at the cephalad thoracic spine (T4–T6), the maximum ventral excursion angle should decrease gradually from 20° to 5°, the entry-point of the screw should be close to the rib head. For apical vertebrae (T7–T9), the maximum ventral excursion angle increased gradually from 5° to 12°. At the caudal thoracic spine (T10–T12), the maximum ventral excursion angle increased, the entry-point should shift 3∼5 mm ventrally.     

脊柱侧凸顶椎椎体及附件旋转角测量及其临床意义

[目的]评估特发性脊柱侧凸患者术前椎体、椎板、棘突旋转角及椎体相对棘突偏移的距离,为指导术中轴状面去旋转及冠状面侧凸矫形提供影像学基础.[方法]选取本院脊柱外科2008年1月～2010年1月收治的30例特发性脊柱侧凸患者,男11例,女19例;平均年龄17.0岁,Cobb角51.9°,术前皆行平卧位顶椎区域CT平扫.测量顶椎椎体、椎板及棘突的旋转角度,然后将椎体、椎板及棘突的旋转角度利用SPSS13.0进行三组定量资料的两两比较,分析三者间的旋转角差异.同时测量椎体相对椎板的偏移距离,计算出其平均值.[结果]顶椎旋转角:椎体平均为17.3°±8.67°,椎板平均为17.6°±11.14°,棘突平均为11.3°±10.51°.经统计分析椎体、椎板与棘突间的旋转角差异具有统计学意义(P=0.017,P=0.013),而椎体与椎板间的旋转角度无明显统计学差异(P =0.906).椎体相对椎板偏移的距离平均为(0.19 ±0.12) cm.[结论]测量脊柱侧凸患者术前CT顶椎椎体、椎板及棘突的旋转度和椎体相对棘突的偏移距离,对术中指导脊柱侧凸的轴状面和冠状面矫形具有一定临床意义.     

An analysis of the effect of the Zielke operation on S-shaped curves in idiopathic scoliosis. The use of EVAs showing that correction of the thoracic curve occurs in its lower part: significance of the thoracolumbar spinal segment

This paper analyzes the initial effect of the Zielke VDS operation on S-shaped idiopathic spinal curves in 17 patients with particular reference to the thoracic spine. The curves are evaluated by conventional methods (Cobb angle, apical vertebral rotation, kyphosis, and lordosis) and by a new method using end vertebra angles (EVAs). Three new surgical correction indices are used. In the lower curve, the surgical correction averaged 81%, and it is usually larger than that induced in the thoracic curve by about 48% (surgical correctability index). The lower curve correction is asymmetric, occurring more in its lower part (lower EVA) than in its upper part (upper EVA), a difference that the authors attribute to the restraint imposed by the rib cage on the upper EVA of the lower curve. In the upper (thoracic) curve, the surgically induced correction is variable and averages 33% (range, 6-69%). It is related significantly to preoperative bending film flexibility. The thoracic curve correction also is asymmetric, occurring more in its lower part (lower EVA) than in its upper part (upper EVA), which usually remains stable. The kyphosis angle decreases by an average of 7 degrees. The thoracic apical vertebral rotation shows variable changes. The findings show that the correction of the upper curve occurs mainly in the thoracolumbar spinal segment. It is suggested that this junctional segment of the spine is of importance in determining the limits of both instrumentation and fusion for idiopathic scoliosis.     

Colour Doppler ultrasonography for evaluation of anterior chest blood supply: the possible role of arterial blood supply to the costosternal junction in the aetiology of idiopathic scoliosis in female adolescents

This prospective comparative study was carried out to investigate the blood supply to the anterior chest wall by measurement of several anatomical and haemodynamic flow parameters of the internal mammary artery, with the use of colour Doppler ultrasonography, in female scoliotics with idiopathic right convex scoliosis in adolescence. Previous investigations have postulated that asymmetry of the breasts in female adolescents may be linked with the development of right convex thoracic scoliosis. This breast asymmetry is supposed to be linked with anatomical and functional asymmetry of the internal mammary artery that is the main supplier to the mammary gland. However, no measurements of anatomical and haemodynamic parameters of the internal mammary artery have been made to justify or reject the hypothesis of asymmetric blood flow volume to the breasts and costosternal junction in female adolescent scoliotics. Twenty female adolescents with right convex thoracic scoliosis and 16 comparable female individuals without spine deformity were examined with roentgenograms (scoliotics only) to measure scoliosis curve, vertebral rotation and concave and convex rib–vertebra angle at three vertebrae (the apical, one level above and one below the apical vertebra). Doppler ultrasonography was used to measure, at the origin of the internal mammary artery, its lumen diameter, cross-sectional area, time average mean flow and flow volume per minute in scoliotics and controls, which were compared with each other. The roentgenographic parameters were compared with the ultrasonographic parameters in the scoliotics to disclose any relationship. The reliability of colour Doppler ultrasonography was high and the intra-observer variability low (ANOVA, P=0.92–0.94). There was no statistically significant difference in the ultrasonographic parameters of the internal mammary artery between right and left side in each individual as well as between scoliotics and controls. In scoliotics the right mammary artery time average mean velocity increases with the convex (P<0.05) and concave (P<0.01) rib–vertebra angle one level above the apical vertebrae and with the apical convex rib–vertebra angle (P<0.05). The right internal mammary artery flow volume per minute increases with convex (P<0.01) and concave (P<0.01) rib–vertebra angle one level above the apical vertebrae and with the apical convex rib–vertebra angle (P<0.05). Left internal mammary artery cross-sectional area increases with convex apical rib–vertebra angle (P<0.01) and concave rib–vertebra angle one level above the apical vertebra (P<0.01). Conclusively, this investigation showed that haemodynamic flow parameters of the right internal mammary artery and anatomical parameters of the left internal mammary artery are significantly correlated with the magnitude of rib–vertebra angles close to the apex of right thoracic scoliosis in female adolescents. This study did not find any evidence for side-difference in vascularity of the anterior thorax wall and, thus, it could not clearly justify previous theories for development of right thoracic scoliosis in female adolescents.A reviewers comment to this paper can be found at     

Lateral bone density variations in the scoliotic spine

Adolescent Idiopathic Scoliosis (AIS) is the most common deformity of the spine, affecting 2–4% of the population. Previous studies have shown that the vertebrae in scoliotic spines undergo abnormal shape changes, however there has been little exploration of how scoliosis affects bone density distribution within the vertebrae.In this study, existing CT scans of 53 female idiopathic scoliosis patients with right-sided main thoracic curves were used to measure the lateral (right to left) bone density profile at mid-height through each vertebral body. Five key bone density profile measures were identified from each normalized bone density distribution, and multiple regression analysis was performed to explore the relationship between bone density distribution and patient demographics (age, height, weight, body mass index (BMI), skeletal maturity, time since Menarche, vertebral level, and scoliosis curve severity).Results showed a marked convex/concave asymmetry in bone density for vertebral levels at or near the apex of the scoliotic curve. At the apical vertebra, mean bone density at the left side (concave) cortical shell was 23.5% higher than for the right (convex) cortical shell, and cancellous bone density along the central 60% of the lateral path from convex to concave increased by 13.8%. The centre of mass of the bone density profile at the thoracic curve apex was located 53.8% of the distance along the lateral path, indicating a shift of nearly 4% toward the concavity of the deformity. These lateral bone density gradients tapered off when moving away from the apical vertebra. Multi-linear regressions showed that the right cortical shell peak bone density is significantly correlated with skeletal maturity, with each Risser increment corresponding to an increase in mineral equivalent bone density of 4–5%. There were also statistically significant relationships between patient height, weight and BMI, and the gradient of cancellous bone density along the central 60% of the lateral path. Bone density gradient is positively correlated with weight, and negatively correlated with height and BMI, such that at the apical vertebra, a unit decrease in BMI corresponds to an almost 100% increase in bone density gradient.     

躯干中轴线在脊柱失稳定评价中的应用

目的探讨躯干中轴线（trunk axis line，TAL）在脊柱侧凸和躯干倾斜诊断和治疗中的临床应用价值。方法选择2006年6月到8月间42例特发性脊柱侧凸患者。a）通过测量侧凸顶椎偏离TAL的距离来评价侧凸程度。b）通过测量TAL与重垂线的夹角来评价躯干倾斜，以倾斜角0°～1°为正常，大于1°为失平衡。结果42例患者主弯顶椎偏离TAL距离均大于1cm，范围为（1．22～8．30）cm，平均（4．35±1．64）cm，其中24例存在躯干倾斜（24／42，57．1％），倾斜角度1．41°～9．52°，平均（3．77±1．52）°。以骨盆为参照，躯干左侧倾斜18例（18／42，75％），右侧倾斜6例（6／24，25％）。结论在脊柱全长片上，根据TAL对冠状面上的躯干倾斜和脊柱侧凸进行诊断和评价是可行的，也有助于侧凸分型，以及顶椎、端椎和稳定椎的确定等，所以该方法值得研究和临床试用。     

青少年特发性脊柱侧凸椎弓根螺钉的误置模式及危险因素

目的 评估青少年特发性脊柱侧凸(AIS)椎弓根螺钉不良置入的模式并分析其原因.方法 收集从2008年7月至9月行后路椎弓根螺钉固定的70例AIS患者的临床资料,其中男性12例,女性58例;年龄12～19岁,平均(14.5±2.7)岁;术前Cobb角40°～125°,平均62.0°±18.2°.术中根据解剖标志徒手置入椎弓根螺钉,所有患者术后均行CT检查.在PACS系统上通过PacsClient软件测量螺钉穿破椎弓根内、外壁以及椎体前缘的距离.定义穿破任一壁超过2 mm为不良置钉.不良置钉中穿破内壁超过4 mm或钉尖使主动脉变形定义为高危置钉.对数据进行统计学分析,探讨不良置钉的危险因素.结果 共置入椎弓根螺钉1030枚,胸椎773枚,腰椎257枚.不良置钉108枚(10.5%),其中穿破外壁35枚,穿破内壁56枚,穿破椎体前缘33枚(其中有16枚既穿破了椎体前缘又穿破了外壁).高危置钉16枚(1.6%).顶椎、顶椎近端第5节段和顶椎远端第4节段的不良置钉率高于其他节段,其中顶椎左侧和顶椎近端第5节段右侧不良置钉率均高于对侧.顶椎区高危置钉率最高,达4.8%.Cobb角>90°组不良置钉率高于Cobb角40°～90°组,椎体旋转Ⅲ～Ⅳ度组不良置钉率高于椎体旋转0～Ⅱ度组.结论 AIS不良置钉集中在顶椎、顶椎近端第5节段和顶椎远端第4节段3个区域,高危置钉多发生在顶椎区,危险因素包括Cobb角大小、旋转程度以及与顶椎的距离.     

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.     

青少年特发性脊柱侧凸患者顶椎区脊髓位置变化及其临床意义

目的:分析青少年特发性脊柱侧凸(AIS)患者顶椎区脊髓偏移和旋转情况,并探讨其临床意义.方法:在28例AIS患者横断面MRI图像上测量顶椎区脊髓中心到椎管前、后内壁及凹、凸侧内壁的距离和脊髓、椎体的旋转角度,将脊髓旋转与椎体旋转的关系按Maruta分型分为O型、U型和R型,并分析脊髓在椎管内的位置及脊髓位置与Cobb角、脊髓旋转角度、椎体旋转角度之间的相关性.结果:顶椎区脊髓中心距脊柱凹侧、凸侧椎管内壁距离分别为7.13±1.89mm、13.68±2.93mm,距凹侧距离明显小于距凸侧距离(t=-9.56,P<0.01);距椎管内壁前、后缘距离分别为7.50±1.63mm、6.99±1.61mm,两者比较无显著性差异(t=1.22.p=0.23).椎体旋转角度为17,53°±6.70°,脊髓旋转角度为16.46°±9.16°,O型8例,U型13例,R型7例.脊髓旋转角度与椎体旋转角度、Cobb角及脊髓中心到凸凹侧椎管内壁的差值之间均呈正相关(分别为r=0.45,P=0.01;r=0.43,P=0.02;r:0.64,P<0.01),与脊髓中心列椎管内壁前后缘的差值之间无显著相关性(r=0.28,P=0.15).结论:AIS患者顶椎区脊髓向凹侧偏移,椎体与脊髓都存在旋转,脊髓的旋转方向因人而异.在行后路脊柱矫形椎弓根螺钉置入时,应特别注意凹侧脊髓及神经根,避免损伤.     

3D MRI在脊柱侧弯畸形矫形术前的临床应用价值

目的探讨3D MRI在脊柱侧弯患者矫形术前的临床应用价值。方法对100例脊柱侧弯患者行术前3DMR检查,采用3D-SPACE T2W序列,多平面重组图像,测量T4、顶椎、L1水平脊髓和椎体的轴位旋转角,观察测量所得顶椎脊髓旋转角与Cobb角的相关性,并进行统计学分析,对顶椎水平脊髓旋转与椎体旋转进行对比。结果顶椎水平脊髓旋转角与Cobb角存在相关性。顶椎水平脊髓旋转可分为3种类型,过度旋转型80例,旋转不足型13例,相反旋转型7例。35例患者最大脊髓旋转角不在顶椎水平。脊髓旋转与椎体旋转不同,在Cobb角大者,大部分脊髓旋转角度大于椎体旋转。MR检查发现2例合并多发神经纤维瘤,1例脊髓空洞,1例蝴蝶椎畸形,5例半椎体并蝴蝶椎畸形,1例合并腹股沟斜疝。结论脊髓、椎体旋转的大小及类型存在差异。脊柱侧弯患者常合并脊髓及椎体多发畸形,3DMR检查在脊柱侧弯畸形矫形术前评估中起着重要作用。     

正常人T4~T12肋骨头与相应椎体椎管解剖学及影像学研究

目的:观察正常人肋骨头和相应椎体及椎管的解剖学及影像学关系。方法:解剖测量组(A组),解剖10具正常成人尸体脊柱标本,测量各节段肋骨头对椎体遮挡率(即双侧肋骨头前缘连线到椎管前壁距离与椎体前缘到椎管前缘距离百分比),以及胸椎前路置钉时最大前方安全角度以及最大后方安全角度(最大前方安全角度即以肋骨头为参照物前路牢固置入螺钉时可向椎体前方形成的最大夹角;最大后方安全角度即以肋骨头为参照物置入螺钉时螺钉不进入椎管可向椎体后方形成的最大夹角);影像测量组(B组),测量30例健康成人胸椎CT平扫片,测量CT照片上各节段肋骨头对相应椎体遮挡率、胸椎前路置钉时最大前方安全角度以及最大后方安全角度。结果:两组肋骨头对相应椎体遮挡率自上而下逐渐减小(从T4约30%到T12约-0.4%),越往头侧肋骨头相对于椎体越靠前,越往下胸椎肋骨头定位相对靠后;前方最大安全角度渐增加(T4约27°到T12约38.3°,P<0.05),后方安全角度逐渐减小(T4约23°到T12约-9°,P<0.05),A、B组间比较统计学差异无显著性(P>0.05)。结论:术前CT片的测量肋骨头和相应椎体椎管的关系可指导胸腔镜辅助下胸椎前路手术置钉,在上段胸椎椎体前路置入螺钉时可考虑部分去除肋骨头,在下段胸椎前路置入螺钉时在肋骨头前缘可安全置入螺钉。