椎弓根螺钉对幼犬腰椎发育的影响

目的通过动物实验观察椎弓根螺钉置入对腰椎形态发育的影响。方法取16只2月龄幼犬，随机分为三组。A组为空白对照组（3只），自L1-7做后路切开显露，暴露目标椎的椎板部分，仅造成对目标椎椎板的软组织剥离损伤。B组为对照组（5只），暴露目标椎椎板后，将螺钉穿过椎弓根，造成对目标椎椎弓根及神经弓中心软骨的隧道破坏后再将螺钉取出，螺钉不留置。C组为实验组（8只），暴露目标椎椎板后，将螺钉穿过椎弓根，造成对目标椎椎弓根及神经弓中心软骨的隧道破坏后不取出，螺钉留置于目标椎椎弓根内。实验的目标椎设计为L2、L4、L6，目标椎的上下两个相邻椎体的相应测量指标的平均值设计为其自身对照。CT测量术后当日及术后3个月的腰椎形态学指标，通过配对t检验比较各组目标椎在不同时期的形态学指标测量值与其自身对照值的差异情况，从而判断椎弓根螺钉的置入对脊椎形态发育的影响效果。结果C组目标椎的椎管面积、横径、纵径、椎弓根长度与相邻脊椎平均值比较差异有统计学意义（P〈0．05），而A组、B组与相邻脊椎平均值比较差异无统计学意义（P〉0．05）。各组椎体横径、纵径、高度与相邻脊椎平均值比较差异无统计学意义（P〉0．05）。结论椎弓根螺钉固定可影响幼犬腰椎椎管及椎弓的发育，可能导致医原性椎管狭窄而对于椎体发育无明确影响。仅破坏神经弓中心软骨联合而不留置螺钉对腰椎发育无明显的影响。     

青少年特发性胸椎侧凸患者胸椎横断面上的发育特征及其意义

目的:探讨青少年特发性脊柱侧凸(adolescent idiopathic scoliosis,AIS)患者青春期胸椎横断面上的发育特征及其意义。方法:收集30例AIS患者(A组)和30例相应年龄无脊柱畸形的青少年(N组)的胸椎CT片,每组根据研究对象年龄组成再分为两个亚组,每个亚组均为15例。低龄AIS组(A1组)和高龄AIS组(A2组)平均年龄分别为10.6岁和16.8岁;低龄对照组(N1组)和高龄对照组(N2组)平均年龄分别为10.8岁和17.3岁。在AIS患者侧凸区(T5～T12)及对照组相应椎体横断面CT上分别测量椎体的横径和纵径、椎管的横径和纵径、椎弓根长度和直径、椎板长度和直径。对相同年龄段的AIS和对照组、同一组内的两个亚组以及每个亚组患者左右侧(凹凸侧)的各个相应参数进行比较分析。结果:每组内高龄亚组的椎体均较低龄组增大,但同年龄层的两亚组无明显差异;N组两个亚组间椎管大小无明显差异,而A2组椎管横径明显大于A1组以及N2组。高龄亚组的椎弓根长度、直径及椎板长度和相应低龄亚组相比均无明显差异,但A2组凸侧以及N2组的椎板直径明显大于相应低年龄组。N组内左右侧后弓测量参数无明显差异,A1组和A2组凹侧椎弓根较凸侧长,但差异无显著性。同年龄层两亚组的椎弓根、椎板的直径、长度均无明显差异。结论:在青春期,AIS患者脊椎后弓可能存在膜内成骨异常,而神经中央软骨对AIS脊椎发育没有明显的影响。     

幼猪胸腰椎椎弓根参数的CT测量对置钉的指导意义

[目的]采用CT扫描测量约克夏幼猪的胸腰椎椎弓根螺钉置入的相关参数,提供动物实验的解剖学参考数据。[方法]10只6周龄的雌性约克夏幼猪进行CT平扫三维重建后测量T1～L5的椎体高度、椎体横径、椎体纵径、椎管横径、椎弓根骨性通道全长、椎弓根宽度等参数,按照测量数据置入椎弓根螺钉,术后再次行CT扫描检查,评估螺钉置入准确性。[结果]根据CT影像学测量结果,椎弓根宽度平均为5.3～7.4 mm,椎弓根骨性通道全长平均为18.8～22.6 mm,椎弓根水平面置入角度平均为32.1°～44.4°之间。根据测量数据,选取直径为4.5 mm,长度为25 mm的椎弓根螺钉,并在幼猪脊柱成功置入,固定效果可靠。[结论]尽管幼猪的脊椎较小,通过术前CT测量的指导,可以有效地指导椎弓根螺钉的置入。     

胸椎椎弓根形态测量研究

目的:观察不同节段胸椎椎弓根形态特征,探讨其临床意义。方法:测量40具国人胸椎标本的椎弓根横径、矢状径、矢状面夹角、椎弓根间距、椎弓根后缘皮质到椎体前缘皮质距离及椎弓根-椎板夹角,观察椎弓根后缘中点与相应横突根部的关系。结果:（1）除T1外,各节段椎弓根矢状径均明显大于横径（P<0.01）;（2）椎弓根矢状面夹角从T1到T9逐渐减小,T10以下为负角;（3）椎弓根后缘皮质沿其轴线到椎体前缘的长度从T1到T7逐渐增加,T7到T12基本相同;（4）T1与T12椎弓根螺钉拟进钉点位于横突根部中点,T2及T11位于横突根部中上1/3点,其余各节段均位于横突根部上缘。结论:进行胸椎椎弓根螺钉固定时,应根据不同节段椎弓根形态特点,结合X线片或CT片,选择相应的螺钉直径、长度、进钉部位及方向。     

腰骶椎经皮椎弓根螺钉相关放射学数据测量及临床意义

[目的]为腰骶椎经皮椎弓根螺钉置入提供直观的影像学数据资料。[方法]测量245例成人腰骶椎X线片及CT片相关数据,包括L1~S1各椎弓根横径及纵径、椎弓根间距、上下相邻椎同侧椎弓根间距、椎弓根轴线与上关节突后缘及椎体前缘交点间距、椎弓根水平位穿刺角(transverse puncture angle,TPA)、椎弓根矢状位穿刺角(sagittal puncture angle,SPA)。[结果]椎弓根横径从L1~5呈逐渐增大趋势,纵径从L1~3逐渐减小,L4、5纵径似有渐增趋势但均L1~3,而S1纵径及横径均变小。椎弓根间距从L1~5呈逐渐增大,相邻椎体同侧椎弓根间距从L1~S1逐渐减小。这些数据男女性别间差异有统计学意义(P0.05)。TPA从L1~S1逐渐增大,SPA从L1~S1由正变负,增大趋势明显,男女性别间差异无统计学意义(P0.05)。[结论]腰骶椎椎弓根大小、椎弓根间距、上下相邻椎同侧椎弓根间距、TPA、SPA呈规律变化,在经皮椎弓根螺钉置入穿刺手术中利用相应数据有利于穿刺点的定位,同时遵循变化规律可以增加穿刺成功率。     

T4椎弓根-肋骨复合体横纵径的相关测量

目的:测量T4椎弓根-肋骨复合体的横纵径相关数据并探讨其意义。方法:12例随机成人胸椎,男7例,女5例;平均年龄23岁(19～28岁)。采用病例自身对照分组,即同一病例、同侧T4椎弓根与椎弓根-肋骨复合体对照。所用设备为GE公司Lightspeed16排螺旋CT,自T3至T5行CT扫描及三维重建。测量参数:椎弓根横径、椎弓根-肋骨复合体横径、椎弓根纵径、椎弓根-肋骨复合体纵径、椎弓根-肋骨复合体重叠纵径。结果:T4椎弓根-肋骨复合体中的椎弓根与肋骨部分重叠,椎弓根横径与椎弓根-肋骨复合体的横径比较差异有统计学意义(P<0.05);椎弓根纵径与椎弓根-肋骨复合体纵径间比较差异无统计学意义(P>0.05),椎弓根-肋骨复合体重叠纵径与椎弓根纵径或复合体纵径间差异均有统计学意义(P<0.05)。结论:T4椎弓根-肋骨复合体中椎弓根与肋骨是部分而非完全重叠,且椎弓根或复合体的纵径均不能等同于重叠纵径。     

椎弓根螺钉系统固定对椎体生长发育的影响

目的:探讨椎弓根螺钉系统固定对5岁以下婴幼儿椎体生长发育的影响。方法 :回顾性分析2000年1月～2016年12月在我院行双侧椎弓根螺钉固定的先天性脊柱侧凸患儿,年龄≤5岁,随访时间至少5年。在术前与末次随访时,于CT轴位图像上测量患者固定椎和邻近非固定椎的椎体及椎管相关参数(椎体及椎管前后径和横径、椎管面积及双侧椎弓根长度)。计算各项参数的生长值(末次随访数值-术前数值)和生长百分比(增长值除以末次随访值)。将胸椎和腰椎的参数进行分组比较。采用统计学的方法比较组间差异。结果:本研究共纳入13例患者,接受手术时的平均年龄为3.4±1.1岁(2～5岁),平均随访7.2±2.2年(5～11年)。所有患者均接受半椎体切除、椎弓根螺钉固定、短节段融合。研究共纳入69个椎体,包括43个固定椎以及26个非固定椎。在末次随访时,所有椎体的各项参数均得到明显增加。固定椎椎管前后径的生长值(2.2±1.7mm)与椎管面积(72.8±48.5mm~2)明显大于非固定椎(1.1±1.3mm,39.2±26.3mm~2),固定椎椎管前后径的生长百分比[(11.2±7.1)%]与椎管面积生长百分比[(21.3±11.6)%]明显大于非固定椎[(6.0±6.0)%,(13.4±8.1)%],固定椎椎体前后径的生长值(3.8±2.5mm)明显小于非固定椎(6.1±3.0mm),生长百分比[(20.5±12.1)%]也明显小于非固定椎[(28.1±11.0)%],差异均具有统计学意义(P0.05)。在腰椎椎体中,结果类似。在随访过程中,非固定腰椎椎管形状发生了明显的变化,而在固定腰椎体中此形状变化不明显。结论:椎弓根螺钉系统固定可能会减缓椎体的生长发育,间接加速椎管的生长发育,可能阻止或减缓腰椎椎管形状的演变。但其影响较小,椎弓根螺钉固定的椎体较术前均有明显的生长。所以,在小于5岁的婴幼儿中应用椎弓根螺钉系统固定对椎体生长发育并无严重影响。     

胸椎椎弓根-肋骨复合体的解剖及影像学研究

目的 探讨胸椎椎弓根-肋骨复合体的解剖结构影像学特点及其临床意义.方法 取4具成人新鲜尸体胸椎脊柱标本.主要测量参数(数据)包括:椎弓根及椎弓根-肋骨复合体的横径、螺钉最长值、矢状角,以及椎弓根、椎弓根-肋骨复合体以及椎弓根-肋骨重叠的纵径.测量中将尸体标本与CT影像测量(含二维、三维重建)相结合.结果 椎弓根-肋骨复合体是一立体结构,椎弓根与肋骨不在同一平面,且两者位置关系随不同节段而发生变化.椎弓根-肋骨复合体纵径值T1最小,为(12.6±0.8)mm,T11最大,为(16.9±1.1)mm.椎弓根-肋骨重叠纵径值T1最小,为(7.2±0.3)mm,T10最大,为(11.8±1.0)mm.椎弓根纵径与椎弓根-肋骨复合体纵径间差异无统计学意义(P＞0.05),椎弓根纵径、椎弓根-肋骨复合体纵径均与椎弓根-肋骨重叠纵径间差异有统计学意义(P＜0.05).结论 椎弓根-肋骨复合体是一较复杂的立体结构,椎弓根-肋骨重叠纵径应被视为该复合体的真实或有效纵径.     

1～6岁正常小儿胸椎椎弓根形态学研究

【摘要】 目的：测量1～6岁小儿胸椎椎弓根的形态学参数,为小儿胸椎椎弓根螺钉固定提供解剖学依据。方法：收集2009年7月~2010年1月在北京儿童医院行胸部CT检查的1～6岁非脊柱疾患小儿胸椎螺旋CT影像资料。根据年龄将入组儿童分为1～岁组（1组）,2～岁组（2组）,4～6岁组（3组）,每组20例。每例均测量T1～T12左右两侧椎弓根参数共24组数值。将64排螺旋CT平扫胸椎的三维重建数据传至工作站,在多平面重建技术下获得每个椎弓根的矢状面及横断面成像,测量胸椎椎弓根横径（内外径）、纵径（内外径）、骨-螺钉通道长度、椎弓根横断面夹角、椎弓根矢状面夹角,并将上述各参数与年龄进行相关性分析,椎弓根横断面夹角和椎弓根矢状面夹角年龄组间采用多重T检验。结果：（1）椎弓根的横径（内外径）T1～T4逐渐减小,T5～T12逐渐增大;横内径值（除T1、T6、T11、T12外）与年龄无显著相关性（rs：0.011～0.363,除T1、T6、T11、T12外,P>0.05）,其随年龄增长变化不明显;横外径值（除T4外）与年龄均存在显著正相关性（rs：0.151～0.539,除T4外,P<0.05）,其随年龄增长而增长。（2）椎弓根纵径（内外径）T1～T12逐渐增大,除T1外纵径均大于横径;各节段参数与年龄均存在显著正相关性（纵内径rs：0.526～0.786,纵外径rs：0.692～0.864,P<0.05）。（3）骨-螺钉通道长度各年龄组中最短为T1或T2,最长为T9或T10,T1～T9有逐渐增加的趋势,T10～T12有逐渐减小的趋势;各节段参数与年龄均存在显著正相关性（rs：0.299～0.676,P<0.05）。（4）椎弓根横断面夹角最大为T1,T1～T12逐渐减小,部分小儿T11及T12的椎弓根横断面夹角可达0°甚至负角,除T1外,其余各节段参数与年龄均存在显著负相关性（rs：-0.432～-0.107,除T1 P>0.05外,余P<0.05）,1组与2、3组间存在显著性差异（P<0.05）,2组与3组间无显著性差异（P>0.05）。（5）椎弓根矢状面夹角T1~T12呈下降趋势,各节段参数与年龄无显著相关性（rs：-0.125～0.127,P>0.05）,1、2、3三组间无显著性差异（P>0.05）。结论：1～6岁小儿胸椎椎弓根横外径、纵经、骨-螺钉通道长度与年龄的相关性较大,而椎弓根横内径的生长速度较慢,与年龄的相关性较小;横断面及矢状面夹角与年龄的相关性较小,除1~岁年龄组外,其余年龄段的参数值随年龄增长无明显变化。因此行1～6岁小儿胸椎椎弓根螺钉内固定手术时,应根据患儿年龄及术中情况妥善选择螺钉型号及进钉方式,以避免手术风险。     

青少年特发性胸椎侧凸患者胸椎椎弓根横径的分型及其临床意义

目的 探讨胸椎椎弓根横径的测量及分型在青少年特发性胸椎侧凸患者治疗中的临床意义.方法 对2008年10月至2009年7月收治的30例青少年特发性胸椎侧凸患者(侧凸组)和2008年8月至2009年7月于本院就诊的20例年龄匹配的非侧凸青少年患者(对照组)采用螺旋CT行胸椎连续扫描,在图像编档和通信系统(PACS)上逐层阅片,选择胸椎椎弓根显示最清楚的层面对椎弓根横径进行测量,并根据测量结果将其分为4型.分别对侧凸组凹凸侧和对照组左右侧椎弓根横径进行对比,并对侧凸组与对照组椎弓根分型的构成比进行分析.结果 两组患者胸椎椎弓根横径T1～4逐渐减少,T5～12逐渐增加.对照组同节段双侧胸椎椎弓根横径差异无统计学意义(P>0.05).侧凸组顶椎区凹侧的椎弓根横径明显小于凸侧,差异有统计学意义(P<0.05).侧凸组中4型椎弓根的比例明显高于对照组,1型椎弓根的比例低于对照组,差异均有统计学意义(P<0.05).结论 青少年特发性胸椎侧凸患者胸椎椎弓根横径常较小,术前应根据CT胸椎椎弓根形态制定置钉策略,以减少经胸椎椎弓根置入螺钉的并发症的发生.     

The effect of pedicle screw insertion through the neurocentral cartilage on the growth of immature canine vertebra

Objective: To explore the influence of pedicle screw insertion through the neurocentral cartilage (NCC) on the development of vertebrae and spinal canal in an animal experiment. Methods: Sixteen dogs were randomly assigned to three groups: in group 1, posterior muscles at the surgery site were dissected; in group 2, the pedicles were drilled through the NCC by screws; in group 3, screws were placed in the pedicles through the NCC. Vertebrae of T8, T10, T12, L2, L4 and L6 were studied with the average data of the adjacent two vertebrae serving as controls. Spiral computerized tomography (CT) was used to assess the morphologic parameters of studied vertebrae and their controls. Measurements were made by an independent radiologist on the first post‐operative day and 3 months after operation. Paired Student's t‐tests of studied vertebrae and their controls were performed to evaluate the effect of pedicle screw insertion. Results: In group 3, 3 months after operation the area, transverse diameter and anterior‐posterior diameter of the vertebral canal and length of pedicle of studied vertebrae were significantly smaller than those of control vertebrae (P < 0.05). There were no significant differences in morphologic parameters between the studied vertebrae and the control vertebrae in groups 1 and 2 (P > 0.05). Conclusion: (i) Pedicle screw placement has a significant impact on the growth of the canine vertebra canal, and may lead to iatrogenic spinal stenosis, but their placement has no significant effect on the vertebral bodies; and (ii) the NCC can repair itself automatically. Drilling pedicle bone through the NCC with a screw and then removing the screw has no obvious impact on the growth of vertebrae.     

The effect of pedicle screw insertion at a young age on pedicle and canal development

STUDY DESIGN.: A longitudinal case study. OBJECTIVE.: To determine whether pedicle screws placed in an immature spine exert effect on the continued growth of the vertebral body. SUMMARY OF BACKGROUND DATA.: Pedicle screws have revolutionized surgical treatment of spinal deformities by allowing a mode of secure fixation that provides consistently better correction rates in adults and adolescents. In the young child, however, the trajectory of pedicle screws takes them through an open physis: the neurocentral cartilage. There exists little information regarding the possible effect of pedicle screws inserted at a young age on further development of the spine and the spinal canal. METHODS.: Patients undergoing pedicle screw instrumentation of at least 2 levels before the age of 5 years (60 mo) for the first time for any diagnosis and who had been followed for at least 24 months were included. Measurements were performed in instrumented and adjacent noninstrumented levels without visible deformity in pre- and postoperative cross-sectional images and compared using statistical methods. RESULTS.: Ninety segments in 15 patients met the inclusion criteria (average age at instrumentation 46.3 mo [range, 29-60 mo]). Forty segments had no screws and 50 had at least 1 screw. Pedicle length and vertebral body diameter had significantly increased in both groups, whereas spinal canal parameters did not change significantly. No significant difference was observed between the growth rates in levels with or without screws in pedicle length, vertebral body diameter, or spinal canal parameters (anterior-posterior and interpedicular diameters, and area). CONCLUSION.: Pedicle screw instrumentation performed before the age of 5 years does not cause a negative effect on the growth of pedicles, the transverse plane of the vertebral body, or the spinal canal. It can be safely performed in the treatment of deformity in this age group.     

The effect of pedicle screw instrumentation at a young age on upper thoracic vertebra and canal development

BACKGROUND CONTEXTPedicle screws are widely used in spinal surgeries. Pedicle screw fixation has shown better clinical effects than other techniques by providing steady fixation from the posterior arch to the vertebral body. However, there are several concerns about the impact of pedicle screw instrumentation insertion on vertebral development in young children, including early closure of the neurocentral cartilage (NCC). The effect of pedicle screw insertion in an early age on further growth of the upper thoracic spine is still unclear.PURPOSEThis study aimed to evaluate the impact of pedicle screw insertion on further growth of the upper thoracic vertebra and spinal canal.STUDY DESIGNA retrospective case study.PATIENT SAMPLETwenty-eight patients.OUTCOME MEASUREMENTSX-ray and CT parameters including length, height and area of the vertebrae and spinal canal were manually measured.METHODSTwenty-eight patients who underwent pedicle screw fixation (T1-T6) before the age of 5 years from March 2005 to August 2019 at Peking Union Medical College Hospital were recruited, and records were retrospectively reviewed. Vertebral body and spinal canal parameters were measured at instrumented and adjacent noninstrumented levels and compared using statistical methods.RESULTSNinety-seven segments met the inclusion criteria (average age at instrumentation 44.57 months, range from 23–60 months). Thirty-nine segments had no screws, and 58 had at least one screw. There was no significant difference between the preoperative and final follow-up values of the measurement of vertebral body parameters. No significant difference was observed between the growth rates in levels with or without screws in pedicle length, vertebral body diameter, or spinal canal parameters.CONCLUSIONPedicle screw instrumentation in the upper thoracic spine does not cause a negative effect on the development of the vertebral body and spinal canal in children younger than 5 years old.     

青少年脊柱侧凸患者胸椎椎弓根螺钉置入的准确性和安全性评价

目的：探讨青少年脊柱侧凸患者胸椎椎弓根螺钉置入的准确性和安全性，以减少相关手术并发症。方法：32例青少年脊柱侧凸患者术前均对畸形脊柱进行标准俯卧位CT加密扫描，测量进钉点至椎体前缘的深度、进针角度、椎弓根直径和椎体的旋转角度，根据测得数据确定椎弓根螺钉置入的深度和方向，置入螺钉后再行脊柱全长X线片及CT扫描评价置钉的准确性和安全性。结果：32例共置入226枚胸椎椎弓根螺钉，术后CT加密和X线片观察到205枚螺钉（90．7％）完全在椎弓根皮质骨内。10例21枚螺钉（9.3％）发生错置，7枚螺钉（3．1％）偏外，5枚螺钉（2．2％）偏前外侧（其中2枚螺钉靠近节段血管），4枚螺钉（1．8％）偏下，4枚螺钉（1．8％）直径过大导致椎弓根内壁膨胀内移，1枚螺钉（0．4％）误入椎管导致完全性脊髓损伤。T1～T4错置12枚（18．2％），T5～T12错置9枚（6．1％）；凸侧椎根螺钉置入的准确率为93．8％，凹侧为83．1％。结论：脊柱畸形患者术前应常规采用标准俯卧位CT加密扫描，根据扫描图像测得的相关数据可为术中准确置入椎弓根螺钉提供重要参考依据。在青少年脊柱侧凸患者胸椎椎弓根螺钉置入有一定的误置率，螺钉发生错置多见于上胸椎和凹侧．术中应高度重视。     

Pedicle and transverse process screws of the upper thoracic spine. Biomechanical comparison of loads to failure

STUDY DESIGN: An In vitro biomechanical load-to-failure test. OBJECTIVES: To determine the comparative axial pullout strengths of pedicle screw versus transverse process screws in the upper thoracic spine (T1-T4), and to compare their failure loads with bone density as seen on computed tomography. SUMMARY OF THE BACKGROUND DATA: The morphology of the upper thoracic spine presents technical challenges for rigid segmental fixation. Though data are available for failure characteristics of cervical-lateral mass screws, analogous data are wanting in regard to screw fixation of the upper thoracic spine. METHODS: Ten fresh-frozen human spines (T1-T4) were quantitatively scanned using computed tomography to determine trabecular bone density at each level. The vertebrae were drilled and tapped for the insertion of a 3.5-mill meter-diameter cortical bone screw in either the pedicle or the transverse process position. A uniaxial load to failure was applied. RESULTS: The mean ultimate load to failure for the pedicle screws (658 N) was statistically greater than that of the transverse process screws (361 N; P < 0.001). The T1 pedicle screw sustained the highest load to failure (775 N). No significant difference was found between load to failure for the pedicle and transverse process screws at T1. A trend toward decreasing load to failure was seen for both screw positions with descending thoracic level. Neither pedicle dimensions nor screw working length correlated with load to failure. CONCLUSIONS: Upper thoracic pedicle screws have superior axial loading characteristics compared with bicortical transverse process screws, except at T1. Load behavior of either of these screws was not predictable based on anatomic parameters.     

In vivo accuracy of thoracic pedicle screws.

STUDY DESIGN: A retrospective observational study of 279 transpedicular thoracic screws using postoperative computed tomography (CT). OBJECTIVE: To determine the accuracy of transpedicular thoracic screws. SUMMARY OF BACKGROUND DATA: Previous studies have reported the importance of properly placed transpedicular thoracic screws. To our knowledge, the in vivo accuracy of pedicle screw placement throughout the entire thoracic spine by CT is unknown. METHODS: The accuracy of thoracic screw placement within the pedicle and vertebral body and the resultant transverse screw angle (TSA) were assessed by postoperative CT. Cortical perforations of the pedicle were graded in 2-mm increments. Screws were regionally grouped for analysis. RESULTS: Forty consecutive patients underwent instrumented posterior spinal fusion using 279 titanium thoracic pedicle screws of various diameters (4.5-6.5 mm). The regional distribution of the screws was 39 screws at T1-T4, 77 screws at T5-T8, and 163 screws at T9-T12. Fifty-seven percent of screws were totally confined within the pedicle. Although medial perforation of the pedicle wall occurred in 14% of screws, in <1% there was >2 mm of canal intrusion. Lateral pedicular perforation occurred in 68% of perforating screws and was significantly more common than medial perforation (P < 0.0005). Seventeen screws penetrated the anterior vertebral cortex by an average of 1.7 mm. Screws inserted between T1 and T4 had a decreased incidence of full containment within the pedicle (P < 0.0005) and vertebral body (P = 0.039) compared with T9-T12. The mean TSA for screws localized within the pedicle was 14.6 degrees and was significantly different from screws with either medial (mean 18.0 degrees ) or lateral (mean 11.5 degrees ) pedicle perforation (P < 0.0005). Anterior vertebral penetration was associated with a smaller mean TSA of 10.1 degrees (P = 0.01) and with lateral pedicle perforation (P < 0.0005). There were no neurologic or vascular complications. CONCLUSIONS: Ninety-nine percent of screws were fully contained or were inserted with either < or =2 mm of medial cortical perforation or an acceptable lateral breech using the "in-out-in" technique. Anterior cortical penetration occurred significantly more often with lateral pedicle perforation and with a smaller mean TSA. The incidence of fully contained screws was directly correlated with the region of instrumented thoracic spine.     

胸椎经关节突关节椎弓根螺钉固定的可行性研究

 目的明确胸椎后路经关节突关节椎弓根螺钉固定的解剖学可行性和技术参数.为临床应用提供参考。方法取 20具胸椎标本.仔细解剖胸椎的后侧和前侧方.以清楚地暴露胸椎椎板和椎弓根。以椎板下缘向上、外缘向内各 7 mm为进钉点.在 T_1.2、T_5.6、T_9.10直视下置入经关节突关节椎弓根螺钉.通过直接的置钉和 CT重建.观察胸椎后路经关节突关节椎弓根螺钉实际置钉的可行性.测量经关节突关节椎弓根螺钉内固定进钉角度和钉道长度。结果所有胸椎后路经关节突关节椎弓根螺钉均由上位胸椎下关节突经关节突关节.进入下位胸椎的椎弓根.成功置入下位胸椎的椎体内。重建 CT测量发现螺钉在横断面的外倾角度为 2.1°±0.7°.在矢状面的尾倾角度为 41.4°±3.2°.在各节段间略有不同.但差异无统计学意义。平均的螺钉钉道长度为(40.6±4.9) mm.钉道长度由上胸椎向中、下胸椎呈逐渐增加趋势.差异有统计学意义(F=74.09, P<0.01)。结论胸椎后路经关节突关节椎弓根螺钉具有解剖学可行性.可以作为胸椎椎弓根螺钉固定的一种补充内固定方法.但置钉时要求较高的准确性。     

Computer-assisted pedicle screw placement for thoracolumbar spine fracture with separate spinal reference clamp placement and registration

BACKGROUND: The objective of the study was to improve the accuracy of computer-assisted pedicle screw installation in the spine. This study evaluates the accuracy of computer-assisted pedicle screw placement with separate spinal reference clamp placement and registration on each instrumented vertebra for thoracolumbar spine fractures. METHODS: Postoperative radiographs and CT scans assessed the accuracy of pedicle screw placement in 21 adult patients on each instrumented vertebra. Screw placements were graded as good if the screws were placed in the central core of the pedicle and the cancellous portion of the body. Screw placements were graded as fair if the screws were placed slightly eccentrically, causing erosion of the pedicular cortex, and with less than a 2-mm perforation of the pedicular cortex. Screw placements were graded as poor if screws were placed eccentrically with a large portion of the screw extending outside the cortical margin of the pedicle and with more than a 2-mm perforation of the pedicular cortex. RESULTS: A total of 140 image-guided pedicle screws were placed in 21 patients: 78 in the thoracic and 62 in the lumbar spine. Of the 140 pedicle screw placements, 96.4% (135/140) were categorized as good; 3.6% (5/140), fair; and 0% were poor. All 5 fair placement screws were placed in the thoracic spine without any mobility. CONCLUSION: Separate registration increases accuracy of screw placement in thoracolumbar pedicle instrumentation. Separate spinal reference clamp placement in the instrumented vertebra provides real-time virtual imaging that decreases the possibility of downward displacement during manual installation of the screw.