3D打印个体化导航模板在胸椎和颈椎椎弓根螺钉植入的临床应用

目的 研究数字化(3D)打印技术的个性化导航模板设计在胸椎和颈椎手术个性化置钉应用的准确性和安全性。方法 2014年7月至2014年11月,对7例需要行胸椎、颈椎椎弓根螺钉植入手术的患者术前通过CT扫描、Mimics软件三维重建建立三维仿真模型。并使用Geomagic软件设计最佳的内固定钉道,然后根据钉道设计导航模板,用3D打印机打印导航模板,用于手术时辅助置钉;术中辅助植入胸椎、颈椎椎弓根螺钉共24枚,术后CT扫描评价螺钉位置,记录有无与螺钉植入的相关并发症。结果 通过导航模板辅助植入的24枚椎弓根螺钉,23枚完全在椎弓根内,1枚穿破椎弓根外壁,穿出距离均小于1.2 mm,椎弓根穿破率为4%,植钉准确率为96%,螺钉位置可接受率为100%。无一例出现螺钉植入有关的神经、血管损伤等并发症。结论 3D打印个体化导航模板辅助胸椎、颈椎椎弓根螺钉植入的植钉准确性高、安全。     

数字化胸椎椎弓根导向模板的设计及其临床应用研究

目的采用数字骨科技术设计并制作胸椎椎弓根导向模板,评价其在胸椎骨折椎弓根钉内固定术中的临床应用价值。方法选取自2013-01—2015-02行胸椎椎弓根钉内固定的5例单椎体骨折,术前根据CT三维重建扫描所得的数据,借助医学影像控制系统Mimics 17.0软件重建伤椎三维数字模型,并根据三维空间内的椎体骨折情况,利用Unigraphics NX 9.0工程软件设计具有椎弓根钉最佳进钉通道且与置钉椎体三维互补的导向模板。通过快速成型技术制作胸椎椎弓根导向模板及椎体,并在术中通过椎弓根导向模板与椎体后侧结构的精确贴合,按照预先设计的置钉通道置钉,术后复查CT评价螺钉位置。结果 5例均顺利完成椎弓根钉置钉操作,共置入30枚椎弓根钉,置入螺钉长度为30~45 mm,直径为5.0~7.0 mm。按改良置钉分级标准评定椎弓根钉置入结果:Ⅰ级19枚,Ⅱ级9枚,Ⅲ级2枚。所有患者均获得12~24(13.00±4.12)个月随访,未发现与置钉相关的神经根、脊髓等损伤症状,无螺钉松动、退出、断裂。结论胸椎骨折内固定术中采用数字化椎弓根导向模板辅助椎弓根钉置入较传统置钉方法有更快速、安全和精确的优势。     

改良3D打印导航模板辅助寰枢椎椎弓根螺钉置钉的准确性分析

目的 :探讨改良3D打印导航模板辅助寰枢椎椎弓根螺钉置钉的准确性。方法:选择我院2015年6月~12月期间行寰枢椎手术的患者17例,男11例,女6例;年龄25~56岁,平均43.3±8.7岁;寰枢椎骨折脱位13例,寰枢椎畸形4例。术前将患者的寰枢椎CT数据导入Mimics17.0软件,生成目标椎体的三维模型,使用逆向工程原理设计与其表面相吻合的反向模板及椎弓根螺钉最佳钉道并生成相应导向通道,标杆相对通道向内侧平移约10mm,将导向通道及标杆与模板拟合一体,设计形成带有导向通道和标杆的改良导航模板。将设计好的导板通过3D打印机打印出来。在3D模型上模拟置钉,体外试验确认方案可行后再将改良导航模板消毒、灭菌并应用于临床。术中将改良3D打印导板与寰枢椎紧密贴合。术者分别以电钻及手钻通过导向通道,以标杆为参照物及导向杆,通过导向通道钻探螺钉通道后取下导板,攻丝后顺钉道置入椎弓根螺钉。将术前规划钉道与术后螺钉配对拟合进行螺钉精确性分析,并以Kawaguchi等评价法判断螺钉位置的优劣等级。结果:手术时间106±11min,术中出血量为220±73ml。共置入68枚颈椎椎弓根螺钉,其中寰椎与枢椎各34枚。术前预设进钉点、内倾角及头倾角与术后相比差异均无统计学意义(P0.05)。术后Kawaguchi等评价法显示:0级占97.06%(66/68),Ⅰ级占2.94%(2/68),有2枚螺钉穿破骨皮质,Ⅱ、Ⅲ级螺钉数为0。结论:通过改良3D打印导板辅助寰枢椎椎弓根置钉,可提高与术前预设最佳钉道的吻合度、精确匹配术前计划,可提高临床手术置钉的准确性,减少偏差。     

3D打印导航模板引导双侧下颈椎前路椎弓根螺钉置钉的可行性

目的 :通过3D打印技术及骨科数字化技术制作下颈椎前路椎弓根螺钉置钉导航模板,观察模板辅助下置钉的准确性。方法:选取正常成人颈椎湿性标本10具(男、女各5具),将椎前软组织剔除,采用64排薄层CT扫描后获取其DICOM格式数据,导入Mimics软件后三维建模并为颈前路椎弓根螺钉选取理想钉道,设计建立螺钉导航模板后导出其STL数据,通过3D打印机快速打印成型。在导航导板引导下进行下颈椎前路椎弓根螺钉置钉,通过X线及CT评价螺钉的准确性。结果:10具尸体分别于C3~T1每节段置入2枚螺钉,共计120枚,根据螺钉的位置将其分为4级:0级,螺钉完全在椎弓根内,共115枚;1级,螺钉穿破椎弓根皮质,穿出部分小于螺钉直径的25%,1枚;2级,螺钉穿破椎弓根皮质,穿出部分为螺钉直径的25%~50%,3枚;3级,螺钉穿出椎弓根部分大于螺钉直径的50%,1枚。5枚穿破椎弓根皮质者2枚穿破椎弓根内侧皮质,3枚穿破外侧皮质,总体准确性为95.8%。结论:在湿性尸体颈椎标本上应用3D打印及骨科数字化技术制作的导航模板辅助行下颈椎前路椎弓根螺钉置钉的准确性高,为临床应用提供了依据。     

3D打印技术辅助中上胸椎椎弓根置钉的准确性分析

目的评价3D打印技术在中上胸椎"分水岭"区域损伤(T3~7)椎弓根置钉时的应用价值。方法回顾性分析自2013-03—2016-02手术治疗的7例T3~7骨折或脱位。对患者进行薄层CT扫描,采用3D打印技术打印出中上胸椎实体模型,在模型上标定需固定节段的椎弓根钉进钉点(Magerl法),测量每一个节段螺钉的直径、长度、内倾角、头倾(尾倾)角,然后选择合适的椎弓根钉模拟置钉。结果本组共置入56枚椎弓根钉,按目前通行的评估椎弓根钉准确性的方法,在CT平扫的影像上对椎弓根穿透的程度进行分级:0级33枚,1级18枚,2级4枚(穿破外侧壁),3级1枚(穿破外侧壁,未造成不良后果),准确率91.1%。结论对于中上胸椎椎弓根置钉困难的患者,尤其是需要长节段置钉时,可以在3D打印的实体模型上模拟置钉,选择安全、有效的椎弓根钉,提高徒手置钉准确率,缩短了年轻医师的学习曲线。     

基于3D打印技术辅助逆向耻骨上支外侧髓内拉力螺钉置钉个性化导向模板的初步研制

目的:观察利用数字化导向模板技术和3D打印制作的个体化逆向耻骨上支外侧髓内拉力螺钉导向模板的可行性。方法:回顾性选择1例骨盆骨折患者,男性,23岁,分型为LCⅡ型骨折。根据CT薄层扫描数据输入3D打印机打印1∶1骨盆模型,Mimics等软件设计钉道并通过逆向工程软件设计数字化导向模板,3D打印导板固定模型后置入直径2.0 mm克氏针,通过影像学观察其准确性。结果:3D打印的骨盆模型及数字化个性化导向定制的手术导向板能够满足耻骨上支外侧骨折置钉的要求,克氏针置入后经X线及CT证实与手术设计一致,导板与骨性标志贴合良好。结论:基于3D打印技术的个性化导向模板可实现逆向耻骨上支外侧髓内拉力螺钉置钉的精确置入,并且可以节省手术时间及减少患者及医护人员的射线暴露次数。     

个体化3D打印导向模板辅助胸腰椎椎弓根螺钉置入在强直性脊柱炎中的应用研究

目的 :评价个体化设计定制3D打印椎弓根螺钉导向模板辅助强直性脊柱炎(ankylosing spondylitis,AS患者胸腰椎椎弓根螺钉置入的准确性与安全性。方法:纳入2016年1月至2019年9月收治的8例AS患者的胸腰椎三维CT检查数据,利用Mimics 17.0、ideaMaker等计算机软件设计AS胸腰椎椎弓根螺钉导向模板,并利用3D打印机打印制作全部病例的实体模型(T_(10)-L_2),每例2份,分为导板辅助螺钉置入组(实验组)和徒手置钉组(对照组)。两组胸腰椎椎弓根螺钉均由同一名脊柱外科医师负责置入。根据术后CT影像结果评估两组椎弓根螺钉置入的准确性,并对螺钉置入情况进行分级:0级和1级螺钉为可接受置钉,2级和3级为不可接受置钉。同时比较术前3D打印软件虚拟设计的椎弓根螺钉的直径、长度、进钉点与后正中线的距离等指标与术中实际使用情况。结果:导板辅助螺钉置入组设计并打印出AS胸腰椎3D打印椎弓根螺钉导向模板23块,辅助置入螺钉46枚,可接受螺钉为44枚;置入单枚螺钉平均时间为(4.20±1.15) min,X线机透视次数为(5.00±1.25)次,置钉过程中螺钉和克氏针平均调整次数为(1.76±1.32)次。徒手置钉组使用传统影像学透视徒手方法置钉46枚,可接受螺钉30枚;置入单枚螺钉平均时间为(14.67±2.23) min,X线机透视次数为(14.46±2.21)次,螺钉和克氏针平均调整次数为(4.76±3.39)次。导板辅助螺钉置入组与徒手置钉组螺钉置入成功率分别为95.65%(44/46)和56.22%(30/46),差异有统计学意义(χ~2=13.538,P0.05);术前3D打印软件虚拟设计的椎弓根螺钉的直径、长度、进钉点与后正中线的距离,与术中实际使用情况差异无统计学意义(P0.05);导板辅助螺钉置入组置入单枚螺钉的时间、X线机透视次数及置钉过程中螺钉和克氏针平均调整次数均明显少于徒手置钉组(P0.01)。结论:3D打印技术定制个体化椎弓根螺钉导向模板显著提高了置钉的安全性、准确性及手术效率,尤其适用于AS合并骨折脱位等须行后路椎弓根螺钉固定的胸腰椎椎体。     

3D打印个性化异形解剖导向钢板辅助经口前路寰枢椎置钉的数字化研究

目的 探讨3D打印个性化异形解剖导向钢板辅助经口前路寰枢椎置钉的可行性。方法 选取2018年6月—2020年12月中国科学院大学宁波华美医院收治的5例难复性寰枢椎脱位患者的影像学资料,利用3D打印技术制作寰枢椎3D模型并设计寰枢椎个性化异形解剖导向钢板。在体外进行钢板贴合度实验,记录3D模型的打印时间、钉道设计时间及异形解剖导向钢板制作时间;记录导向钢板的钉道方向、角度及长度,并与基于CT 3D重建数据设计的虚拟钉道进行对比,评估螺钉位置的准确性。结果 3D模型打印时间、钉道设计时间及异形解剖导向钢板制作时间分别为（210.0±10.3）min、（15.0±2.7）min、（1 440.0±25.3）min。3D打印寰枢椎个性化异形解剖导向钢板与模型贴合良好,X线和CT检查证实寰枢椎螺钉位于骨性钉道内,逆向寰枢椎椎弓根螺钉钉道方向、角度及长度与基于CT 3D重建数据设计的钉道一致。结论 3D打印寰枢椎个性化异形解剖导向钢板辅助经口前路寰枢椎置钉可实现钢板良好贴合及螺钉精确置入,为寰枢椎脱位的治疗提供了一种更为精确的方案。     

3D打印导航模板在辅助寰枢椎椎弓根螺钉置入中的应用价值

目的:探讨三维(3D)打印导航模板辅助寰枢椎椎弓根螺钉置钉的价值。方法:回顾性分析2013年1月~2015年10月我院收治的43例寰枢椎骨折和/或脱位患者,均行后路寰枢椎切开复位内固定术。按手术方式不同分为3D打印导航模板组(19例)和传统置钉组(24例)。3D打印导航模板组术前将患者的颈椎CT数据导入Mimics 17.0软件,行3D重建并设计带钉道的导航模板后打印、消毒;术中将导航模板与置钉椎体贴合紧密后,通过定位孔钻孔、置钉。传统置钉组在C型臂X线机透视下徒手置钉。统计并对比两种置钉方法的准确率,通过测量并比较术前预设钉道角度与术后实际钉道角度差异评估进针角度的精确性。比较两组的置钉时间、手术时间、透视次数、术中出血量及患者颈肩部疼痛视觉模拟评分(visual analogue scale,VAS)和日本骨科协会(Japanese Orthopaedic Association,JOA)颈椎神经功能评分的差异情况。结果:两组患者在性别、年龄、临床诊断、病变节段、合并症及术前是否牵引复位方面均无统计学差异(P0.05)。19例3D打印导航模板辅助置入椎弓根螺钉68枚,置钉准确率94.1%,置钉时间2.2±0.4min/枚,透视次数4.6±1.1次,手术时间197±41min,术中出血量395±64ml;传统徒手置钉组置入椎弓根螺钉76枚,置钉准确率76.3%,置钉时间3.4±0.7min/枚,透视次数9.4±2.7次,手术时间245±67min,术中出血量552±79ml。两组置钉准确率、置钉时间、透视次数、手术时间及术中出血量均有统计学差异(P0.05)。3D打印导航模板组的内倾角及头倾角与预设值无统计学差异0.05),置钉角度的精确性明显优于徒手置钉组(P0.05)。术后3d、6个月及12个月患者颈肩部VAS及颈椎JOA评分较术前明显好转(P0.05),而术后6个月及12个月两组间颈肩部VAS及颈椎JOA评分无统计学差异(P0.05)。结论:3D打印导航模板辅助寰枢椎椎弓根置钉可提高置钉准确率,同时还可缩短置钉时间、手术时间,减少透视次数和术中出血量。     

个性化3D打印辅助手术治疗A型颅底凹陷症

[目的]介绍个体化3D打印技术辅助治疗A型颅底凹陷症的技术。[方法] 2017年1月～2018年6月收治A型颅底凹陷症患者21例。对每例患者均行枕颈部CT扫描重建和CTA检查,利用mimics软件重建患者枕颈部3D模型,并对枢椎椎弓根螺钉进针点、进针角度、螺钉直径、长短进行个体化设计,3D打印机打印制作患者枕颈部1:1大小模型和螺钉导向模板,在3D模型及螺钉导向模板的指导下完成手术操作,术后复查枕颈部CT重建扫描,对置钉位置及临床疗效进行对比分析。[结果] 12例患者行前路口咽松解加后路枕颈减压固定融合,9例患者行单纯后路减压复位固定融合术。其中,18例患者均在术中模型、螺钉导板和C臂透视辅助下置入枢椎椎弓根螺钉,3例患者因枢椎椎弓根细小选择置入C3椎体椎弓根螺钉,术后复查枕颈部CT提示寰枢椎脱位完全复位,螺钉位置良好,无患者出现神经和椎动脉损伤,2例患者术后出现颈后伤口感染,清创联合敏感抗生素治疗后痊愈。术后平均随访(6.02±4.47)月,术后1、3、6个月JOA评分,寰齿前、后间隙,脊髓脑干角得到明显改善。[结论]术前个体化3D打印和枢椎弓根螺钉位置设计可以有效提高手术中置钉准确率,减少术中神经和椎动脉损伤的风险。     

Accuracy of upper thoracic pedicle screw placement using three-dimensional image guidance

Background contextPedicle screw malposition rates using conventional techniques have been reported to occur with a frequency of 6% to 41%. The upper thoracic spine (T1–T3) is a challenging area for pedicle screw placement secondary to the small size of the pedicles, the inability to visualize this area with lateral fluoroscopy, and significant consequences for malpositioned screws. We describe our experience placing 150 pedicle screws in the T1–T3 levels using three-dimensional (3D) image guidance.PurposeThe aim of this study was to assess the accuracy of 3D image guidance for placing pedicle screws in the first three thoracic vertebrae.Study designThe accuracy of pedicle screw placement in the first three thoracic vertebrae was evaluated using postoperative thin-section computed tomography (CT) scans of the cervicothoracic region.Patient sampleThirty-four patients who underwent cervicothoracic fusion were included.Outcome measuresRadiological investigation with CT scans was performed during the postoperative period.MethodsThirty-four consecutive patients underwent cervicothoracic instrumentation and fusion for a total of 150 pedicle screws placed in the first three thoracic vertebrae. All screws were placed using 3D image guidance. Medical records and postoperative imaging of the cervicothoracic junction for each patient were retrospectively reviewed. An independent radiologist reviewed the placement of the pedicle screws and assessed for pedicle breach. All cortical violations were reported as Grade 1, 0 to 2 mm; Grade 2, 2 to 4 mm; and Grade 3, greater than 4 mm.ResultsOverall, 140 (93.3%) out of 150 screws were contained solely in the desired pedicle. All 10 pedicle violations were Grade 1. The direction of pedicle violation included three medial, four inferior, two superior, and one minor anterolateral vertebral body. No complication occurred as a result of screw placement or the use of image guidance.ConclusionsUpper thoracic pedicle screw placement is technically demanding as a result of variable pedicle anatomy and difficulty with two-dimensional visualization. This study demonstrates the accuracy and reliability of 3D image guidance when placing pedicle screws in this region. Advantages of this technology in our practice include safe and accurate placement of spinal instrumentation with little to no radiation exposure to the surgeon and operating room staff.     

3D打印模板导航经皮椎弓根螺钉置钉在经椎间孔腰椎椎间融合术治疗腰椎椎管狭窄症中的初步应用

目的探讨3D打印模板导航经皮椎弓根螺钉置钉在经椎间孔腰椎椎间融合术(TLIF)治疗腰椎椎管狭窄症中应用的可行性、准确性和安全性。方法回顾性分析2016年1月—2017年3月本院采用TILF治疗的单节段腰椎椎管狭窄症患者的临床资料,选取10例应用3D打印模板导航置钉的患者作为试验组,选取一般情况相似的10例作为对照组。试验组下肢无临床表现侧在3D打印模板导航下置入螺钉(模板侧),下肢有临床表现侧切开后经Wiltse入路顺导针置入螺钉(穿刺侧);对照组采用传统徒手法置入椎弓根螺钉。记录患者手术时间、出血量、透视时间及次数、螺钉置入的准确性及脊髓、神经损伤并发症发生情况。结果试验组手术时间、出血量少于对照组,差异有统计学意义(P0.05)。试验组模板侧透视时间及次数少于穿刺侧及对照组,差异有统计学意义(P0.05);而穿刺侧与对照组相比差异无统计学意义(P0.05)。试验组无2级螺钉,对照组2级螺钉有4枚。0级螺钉比例,试验组两侧均优于对照组,差异有统计学意义(P0.05);试验组两侧差异无统计学意义(P0.05)。所有患者均无脊髓、神经损伤等并发症发生。结论 3D打印模板导航经皮椎弓根螺钉置钉应用于TLIF治疗腰椎椎管狭窄症是可行的。虽然应用过程中需要注意避免皮肤移动、体位变化对置钉准确性的影响,但仍是一种新的、可选择的微创置钉技术。     

Radiographic verification of pedicle screw pilot hole placement in thoracic spine using Kirschner wires versus spiral wires

To evaluate the feasibility of the pedicle screw pilot holes placement in thoracic spine using the spiral wires as the guide pin.     

3D打印经皮导板辅助经皮后凸成形术治疗骨质疏松椎体压缩性骨折

目的:验证3D打印经皮导板辅助经皮后凸成形术(percutaneous kyphoplasty,PKP)治疗骨质疏松椎体压缩性骨折(osteoporosis vertebral compression fractures,OVCFs)的安全性。方法:对2020年11月至2021年8月,采用PKP治疗的60例OVCFs患者进行回顾性分析,男24例,女36例,年龄72～86(76.5±7.9)岁,其中30例采用常规PKP治疗(常规组),30例采用3D打印经皮导板辅助PKP治疗(导板组)。观察术中椎弓根穿刺时间(穿刺针到椎体后缘)及透视次数,手术总时间,总透视次数,骨水泥注入量,并发症(椎管型骨水泥渗漏),比较两组患者术前和术后3 d的视觉模拟评分(visual analogue scale,VAS)及伤椎前缘压缩率。结果:60例患者均成功实施手术,无椎管型骨水泥渗漏并发症发生。导板组椎弓根穿刺时间(10.23±3.15) min,透视次数(4.77±1.07)次,手术总时间(33.83±4.21) min,总透视次数为(12.27±2.61)次;常规组椎弓根穿刺时间(22.83±3.09)...     

Pedicle screw placement in the thoracic spine: a randomized comparison study of computer-assisted navigation and conventional techniques

Objective： To evaluate the accuracy of computer-assisted pedicle screw installation and its clinical benefit as compared with conventional pedicle screw installation techniques.
Methods： Total 176 thoracic pedicle screws placed in 42 thoracic fracture patients were involved in the study randomly, 20 patients under conventional fluoroscopic control （84 screws） and 22 patients had screw insertion under three dimensional （3D） computer-assisted navigation （92 screws）. The 2 groups were compared for accuracy of screw placement, time for screw insertion by postoperative thincut CT scans and statistical analysis by χ^2 test. The cortical perforations were then graded by 2-mm increments： Grade Ⅰ （good, no cortical perforation）, Grade Ⅱ （screw outside the pedicle 〈2 mm）, Grade Ⅲ （screw outside the pedicle 〉2 mm）.
Results： In computer assisted group, 88 （95.65%） were Grade Ⅰ （good）, 4 （4.35%） were Grade Ⅱ （〈2mm）, no Grade Ⅲ （〉2 mm） violations. In conventional group, there were 14 cortical violations （16.67%）, 70 （83.33%） were Grade Ⅰ （good）, Ⅱ （13.1%） were Grade Ⅱ （〈2 mm）, and 3 （3,57%） were Grade Ⅲ （〉2 mm） violations （P〈0.001）. The number （19.57%） of upper thoracic pedicle screws （ T1-T4 ） inserted under 3D computer-assisted navigation was significantly higher than that （3.57%） by conventional fluoroscopic control （P〈0.001）. Average screw insertion time in conventional group was （4.56 ±1.03） min and （2.54 ± 0.63） min in computer assisted group （P〈0.001）. In the conventional group, one patient had pleura injury and one had a minor dura violation.
Conclusions： This study provides further evidence that 3D computer-assisted navigation placement ofpedicle screws can increase accuracy, reduce surgical time, and be performed safely and effectively at all levels of the thoracic spine, particularly upper thoracic spine.     

CT三维重建立体导航引导技术在胸椎弓根钉置入手术中的应用

目的探讨术前CT三维重建立体导航引导技术在胸椎弓根钉置入手术中的应用方法和临床意义。方法2003年5月-2006年5月采用CT三维重建导航对2t例（122枚）胸椎弓根钉置入手术进行立体引导，其中上胸椎38枚，中下胸椎84枚。男13例，女8例；年龄为13—76岁，平均43岁。术中使用C形臂X线机拍摄正侧位X线片，术后行CT扫描以了解椎弓根钉位置情况。结果术后CT椎弓根位置扫描显示：A级109枚（89．3％）B级6枚（4．9％）；C级3枚（2．5％）；D级4枚（3．3％）。结论术前CT三维重建立体导航引导技术使椎弓根钉按预期的路径精确置入，尤其提高了具有挑战性的胸椎椎弓钉置入的安全性和准确性。     

A novel computer-assisted drill guide template for thoracic pedicle screw placement: a cadaveric study

Introduction  

The objective of this study was to develop a novel, patient-specific, navigational template for thoracic pedicle screw placement.     

The ventral lamina and superior facet rule: a morphometric analysis for an ideal thoracic pedicle screw starting point

Background contextWith the increasing popularity of thoracic pedicle screws, the freehand technique has been espoused to be safe and effective. However, there is currently no objective, definable landmark to assist with freehand insertion of pedicle screws in the thoracic spine. With our own increasing surgical experience, we have noted a reproducible and unique anatomic structure known as the ventral lamina.PurposeWe set out to define the morphologic relationship of the ventral lamina to the superior articular facet (SAF) and pedicle, and describe an optimal medial-lateral pedicle screw starting point in the thoracic spine.Study designWe conducted an in vitro fresh-frozen human cadaveric study.MethodsOne hundred fifteen thoracic spine vertebral levels were evaluated. After the vertebral body was removed, Kirschner wires were inserted retrograde along the four boundaries of the pedicle. Using digital calipers, we measured width of the SAF and pedicle at the isthmus, and from the borders of the SAF to the boundaries of the pedicle. We calculated the morphologic relationship of the ventral lamina and the center of the pedicle (COP) to the SAF.ResultsTwo hundred twenty-nine pedicles were measured, with one pedicle excluded because of fracture of the SAF during disarticulation. The ventral lamina was clearly identifiable at all levels, forming the roof of the spinal canal and confluent with the medial pedicle wall (MPW). The mean distance from the SAF midline to the MPW was 1.36±1.23 mm medial. The MPW was lateral to SAF midline in 34 pedicles (14.85%) and, on average, was a distance of 0.52±0.51 mm lateral. The mean distance from the SAF midline to the COP was 2.17±1.38 mm lateral. The COP was medial to SAF midline in only 11 pedicles (4.80%).ConclusionsThe ventral lamina is an anatomically reproducible structure located consistently medial to the SAF midline (85%). We also found the COP consistently lateral to the SAF midline (95%). Based on these morphologic findings, the medial-lateral starting point for thoracic pedicle screws should be 2 to 3 mm lateral to the SAF midline (superior facet rule), allowing screw placement in the COP and avoiding penetration into the spinal canal.     

Accuracy of percutaneous pedicle screws for thoracic and lumbar spine fractures: a prospective trial

Purpose

The percutaneous insertion technique requires surgical skill and experience. However, there have been few clinical reports evaluating the accuracy of minimally invasive pedicle screw placement using the conventional fluoroscopy method. The purpose of this study was to evaluate the accuracy of percutaneous pedicle screw placement in the treatment of thoracic and lumbar spine fractures using two-plane conventional fluoroscopy.

Methods

A prospective clinical trial was performed. A total of 502 percutaneous pedicle screws in 111 patients, all inserted with the assistance of conventional fluoroscopy, were evaluated. The safety and accuracy of pedicle screw placement were based on the evaluation of postoperative axial 3-mm slice computed tomography scans using the scoring system described by Zdichavsky et al. [Eur J Trauma 30:234–240, 2004; Eur J Trauma 30:241–247, 2004].

Results

427/502 pedicle screws (85 %) were classified as good and excellent concerning the best possible screw length and 494/502 (98 %) were found to have good or excellent position. One screw had to be revised due to medial position with a neurological deficit.

Conclusions

This study demonstrates the feasibility of placing percutaneous posterior thoracolumbar pedicle screws with the assistance of conventional fluoroscopy. Minimally invasive transpedicular instrumentation is an accurate, reliable and safe method to treat a variety of spinal disorders, including thoracic and lumbar spine fractures.