寰枢椎定位导向内固定置钉点、角度、直径及长度的个性化设计

目的：为提高内固定置钉的一次成功率，利用辅助检查资料为寰枢椎椎弓根螺钉的置钉制定简单、实用的个性化方案。 方法：选择2002-01/2006-09解放军第二五一医院骨科患者31例。术中采用自制的寰枢椎定位导向器，根据寰枢椎椎弓根X射线-CT个体化测量的结果，确定进钉点、入钉的角度，选择直径及长度合适的椎弓根螺钉置入。寰椎椎弓根进钉点：左侧（19.93±1.32）mm，右侧（19.16±1.30）mm，寰椎椎弓根向内侧进钉角度：左侧（23.72±2.09）°，右侧（23.35±1.91）°，寰椎向头侧进钉角度（9.00±1.20）°。枢椎椎弓根进钉点：左侧（13.14±0.82）mm，右侧（13.85±0.79）mm。 枢椎椎弓根向内侧进钉角度：左侧（24.52±1.26）°右侧（20.42±1.42）°，枢椎向头侧进钉角度（25.00±3.00）°。 结果：①对31例患者置入124枚椎弓根螺钉，1次置钉成功122枚螺钉，正确率为98.39%，有2枚因内倾角偏差不够，穿破椎弓根的外侧骨皮质而改为2次定位。②2例术后出现枕大神经痛，经对症治疗1个月后痊愈，2例螺钉穿破寰椎左侧椎弓根外侧壁，未发现脊髓、椎动脉损伤。③所有患者X射线片显示寰椎完全复位，枢椎齿状突骨折处对位良好。CT片示螺钉与椎动脉的脊髓位置关系良好。④平均随访10.5个月，均获得骨性融合，未发现钉板断裂材料反应。⑤按JOA评分标准，优16例，良12例，可2例，差1例，优良率90.32%。 结论：X射线-CT个性化设计方案可提高寰枢椎椎弓根螺钉的置入成功率。     

胸椎椎弓根外固定技术的临床应用☆

应用椎弓根外内固定技术2004/2007年在中山大学附属第三医院骨科治疗34例患者，固定前采用CT加密扫描测量进钉点、进钉点至椎体前缘的深度、进钉角度和直径，固定中椎弓根钉入点为横突尖，进钉方向为平均向头侧倾斜10°~ 20°、与中线成角30°~40°，顺椎弓根外侧皮质进入椎体，固定后CT加密扫描观察螺钉周围的皮质骨是否完整、是否靠近节段血管、是否穿透皮质骨，评价置入钉的准确性和安全性。34例患者共置入160枚胸椎椎弓根螺钉,固定后CT加密扫描和X射线片观察到148枚(92.5% )螺钉置入准确，12枚(7.5%)螺钉发生错置。实验结果表明，胸椎椎弓根根外内固定与椎弓根内固定相比，具有更宽的置入宽度，更长的螺钉长度，以及更大的内聚角度，具有安全可靠、简单实用等优点，并具有生物力学优越性，是胸椎后路内固定的一种良好选择。     

自发性寰枢关节脱位后路复位内固定术中枢椎椎弓根螺钉置入不能时的备选方法

目的探讨自发性寰枢关节脱位后路内固定过程中枢椎椎弓根螺钉置入不能时,其他备选螺钉内固定技术的安全性及有效性。方法对贵州省人民医院神经外科未采用枢椎椎弓根螺钉内固定治疗的11例自发性寰枢关节脱位患者的临床资料进行回顾性分析。在枢椎椎弓根螺钉置入不能时,采用枢椎椎板螺钉、峡部螺钉、枢椎下关节突螺钉及延长固定节段至C3侧块螺钉来增加稳定性的方法。手术前后分别行CT及MRI检查,评价脊髓受压程度、脱位复位情况、螺钉位置、骨融合情况;通过比较术前、术后日本骨科协会(JOA)评分来评价疗效。结果 11例患者均为枢椎椎弓根置钉不能,改用备选方法置钉,全部行枕颈钉棒内固定。共置入枢椎椎板锣钉14枚,枢椎峡部螺钉5枚,枢椎下关节突螺钉1枚,延长固定节段至C3侧块螺钉4枚。术中均未发生椎动脉和脊髓神经根损伤。11例患者的寰枢关节脱位均得到不同程度的复位,随访中无患者出现螺钉松动、滑脱、断钉及复位丢失等情况,JOA评分为显著增加。结论对自发性寰枢关节脱位后路内固定过程中枢椎椎弓根螺钉置入不能时,可根据情况,个性化选用枢椎椎板螺钉、峡部螺钉、枢椎下关节突螺钉及延长固定节段至C3侧块螺钉的方法来固定,是可行且有效的。     

O形臂导航辅助经皮椎弓根螺钉内固定的初步应用

目的探讨O形臂导航辅助经皮椎弓根螺钉内固定的准确性与安全性。方法回顾性分析7例经皮椎弓根螺钉内固定病人的临床及影像学资料。病人均在置钉结束后行O形臂系统3D扫描,按照Gertzbein-Robbins分级评估置钉的准确性。结果 7例病人在O形臂导航辅助下共置入29枚椎弓根螺钉,其中Gertzbein-Robbins分级A级23枚(79.31%),B级4枚(13.79%),C级1枚(3.45%),E级1枚(3.45%)。手术共置入29枚克氏针,其中1枚(3.45%)突破椎体前缘。术中无关节突关节受到破坏。1例出现置钉相关神经并发症行再次手术调整椎弓根螺钉。随访(8.29±2.43)个月,无钉棒置入后相关并发症。结论 O形臂导航辅助经皮椎弓根螺钉内固定具有较高的准确性及安全性。     

经椎弓根钉板内固定治疗上颈椎疾患的个性化设计及临床应用

背景：上颈椎疾患从后路行椎弓根固定在国内个别大型医院虽已相继开展,但该手术仍为颈椎外科高难度手术。为了将手术风险降至最低,作者设计了一套个体化手术方案,并结合自行研制的椎弓根定位导向器行术中精确定位置钉,经检索相关数据库在国内未见报道。 目的：提高内固定置钉的一次成功率及植入体的生物力学效应,利用辅助检查资料为寰枢椎椎弓根螺钉的置钉制定简单、实用的个性化方案。 方法：选择2002-01/2006-09解放军第二五一医院骨科患者31例。术中采用自制的寰枢椎定位导向器,根据寰枢椎椎弓根X射线-CT个体化测量的结果,确定进钉点、入钉的角度,选择直径及长度合适的椎弓根螺钉置入。寰椎椎弓根进钉点：左侧(19.93± 1.32) mm,右侧(19.16±1.30) mm,寰椎椎弓根向内侧进钉角度：左侧(23.72±2.09)°,右侧(23.35±1.91)°,寰椎向头侧进钉角度(9.00±1.20)°。枢椎椎弓根进钉点：左侧(13.14±0.82) mm,右侧(13.85±0.79) mm。 枢椎椎弓根向内侧进钉角度：左侧(24.52±1.26)°,右侧(20.42±1.42)°,枢椎向头侧进钉角度(25.00±3.00)°。 结果与结论：①31例患者置入124枚椎弓根螺钉,1次置钉成功122枚螺钉,正确率为98.39%,有2枚因内倾角偏差不够,穿破椎弓根的外侧骨皮质而改为2次定位。②2例术后出现枕大神经痛,经对症治疗1个月后痊愈,2例螺钉穿破寰椎左侧椎弓根外侧壁,未发现脊髓、椎动脉损伤。③所有患者X射线平片显示寰椎完全复位,枢椎齿状突骨折处对位良好。CT片示螺钉与椎动脉的脊髓位置关系良好。④平均随访10.5个月,均获得骨性融合,未发现钉板断裂材料反应。无炎症、排异等宿主反应。⑤按JOA评分标准,优16例,良12例,可2例,差1例,优良率90%。提示从生物力学角度实施植入体置入,可提高寰枢椎椎弓根螺钉的置入成功率。     

三维虚拟图像导航技术在脊柱椎弓根螺钉固定中的应用☆

背景：近年来经椎弓根螺钉固定技术显著提高了脊柱固定强度和融合效率,但是椎弓根螺钉置入位置不佳可能损害脊髓和神经引起严重并发症。 目的：评估置入前CT扫描三维虚拟图像导航技术在脊柱椎弓根螺钉固定中的应用价值。 设计、时间及地点：前瞻性、随机对照观察,于2006-01/2008-12在中国医学科学院北京协和医院骨科完成。 对象：纳入因脊柱疾病行椎弓根螺钉固定的患者95例,导航组45例,常规组50例。 方法：将95例患者按随机数字表法分为2组,导航组术中在计算机导航技术辅助下置入椎弓根螺钉,常规组采用传统的解剖标志法结合术中透视定位置入椎弓根螺钉。 主要观察指标：比较2组间螺钉钉道准备时间、螺钉位置优良率及螺钉置入后并发症的发生率。 结果：导航组中36例患者共置入椎弓根螺钉206枚,优良率96.1%;有9例患者因故未能行导航。常规组50例患者共置入椎弓根螺钉285枚,优良率100.0%,无位置差的螺钉。2组患者的螺钉位置优良率差异无显著性意义(P > 0.05)。导航组的钉道准备时间显著长于常规组[(360±22),(56±8) s,P < 0.01]。2组患者螺钉置入后均无并发症发生。 结论：与传统解剖标志定位法相比,应用置入前CT扫描三维虚拟图像导航技术置入椎弓根螺钉的精度无明显差异,且延长了手术时间,其在脊柱椎弓根螺钉固定中的应用价值有限。     

框架立体定向图像引导颈椎弓根螺钉个体化置钉的实验研究

目的探索一种基于虚拟现实可视化技术的颈椎弓根螺钉置钉方法。方法选取6例成人颅-颈椎标本，改进的四柱式定位框架以螺钉固定于枕颈部，使颅-颈-肩形成统一刚性结构，保持空间位置恒定。CT薄层扫描获取60个椎弓根的空间定位数据，Aero—tech手术规划系统三维建模，设计安全、个体化的置钉路径，导向弓把持下经皮细钻钻孔，套管针导引下置入攻丝，复查CT评价置钉的准确性。结果60个椎弓根置钉中，攻丝与规划路径有偏差者8个，失败率为13％，横突孔方向突破5个，椎管骨皮质突破3个；6例位于C（3-5）（占75％）；2例位于C1、C2椎体（占25％）。结论框架立体定向图像引导的颈椎弓根螺钉个体化置入方向精确，减少置钉的并发症，置钉过程直观、简单，能术前虚拟演示，有临床应用前景。     

单、双侧后外侧椎弓根钉置入并植骨融合治疗退变性腰椎滑脱的随机对照

背景：节段融合辅以椎弓根钉置入内固定治疗退变性腰椎疾病可提高融合率。 目的：比较单、双侧椎弓根钉置入内固定并植骨融合治疗退变性腰椎滑脱的临床疗效和融合率。 方法：将退变性腰椎滑脱患者随机分为2组,分别行双侧与单侧椎弓根钉置入内固定并植骨后外侧融合。 结果与结论：两组患者失血量、输血量、住院时间、手术并发症、临床疗效、融合率和对临近间盘的影响方面差异无显著性意义。单侧内固定组手术操作时间较双侧内固定组明显缩短(P < 0.001)。双侧内固定组置入186枚椎弓根螺钉中有3枚穿透皮质刺激神经根而行二次手术;单侧内固定组置入90枚螺钉未发生与螺钉置入相关的并发症。表明退变性腰椎滑脱患者行单侧和双侧椎弓根钉置入并植骨内固定后外侧融合效果相同,但单侧内固定成本费用低、节省手术时间,置钉时穿破椎弓根皮质刺激神经根的风险小。     

个体优化经椎弓根置钉复位内固定治疗胸腰椎骨折

背景：在日臻成熟的椎弓根螺钉应用技术中,仅满足于将螺钉置入椎弓根中是不够的,而是应根据骨折复位固定要求寻求最佳置钉通道。 目的：验证经椎弓根内固定个体化治疗胸腰椎骨折的有效性和安全性。 方法：对50例胸腰椎骨折患者内固定前X射线片和CT片进行个体化矢状面及水平面椎弓根螺钉置入角、椎弓根横径、间距、钉道深度、椎体前后高、脊柱后凸角及椎管前后径测量,确定胸腰段椎弓根钉道个体优化置钉和复位的安全范围。术中结合解剖定位标志,C臂X射线机监控置钉并复位骨折椎体,确定复位结果。 结果与结论：置钉位置良好,角度及深度适中,内固定后骨折椎体复位高度、后凸角及椎管面积改善(P < 0.01)。经2~26个月随访,骨折均愈合。提示在胸腰段椎弓根钉道个体化影像测量安全范围内,优化置入椎弓根钉和复位是保证置钉内固定安全和椎体骨折复位合理而有效的方法。     

三种置钉方法在下颈椎经椎弓根螺钉置入过程中的比较

背景：目前各种下颈椎椎弓根置钉方法的准确率报道不一,特别是国内常用的椎板部分切除置钉法、Abumi法、管道疏通法缺乏比较。 目的：探讨下颈椎(C3~7)经椎弓根螺钉内固定的可行性,比较椎板部分切除置钉法、Abumi法、管道疏通法在置钉满意率、出血量、置钉时间、并发症等方面的差异。 方法：选择60例需颈后路经椎弓根螺钉内固定治疗的下颈椎疾患病例,随机分成3组,各置入椎弓根螺钉80枚,分别采用椎板部分切除置钉法、Abumi法及管道疏通法。术中计算各方法置钉时间、出血量;出院前观察置钉满意率及在颈椎椎弓根四壁损伤例数的构成比;比较C3~7每一节段的椎弓根外侧壁损伤发生率。 结果与结论：椎板部分切除组、Abumi组及管道疏通组置钉时间依次递减(P < 0.05),置钉满意率依次递增(P < 0.05)。3组间置钉出血量及颈椎椎弓根四壁损伤例数的构成比差异无显著性意义(P > 0.05),椎弓根损伤好发生于外壁。C4、C5节段外壁损伤发生率明显高于C3、C6、C7。提示管道疏通法在经颈后路椎弓根螺钉内固定常规置钉法中优势明显。     

Application of robotic assistance in surgical treatment of degenerative disease of lumbosacral spine

Robotic assistance has gained increasing popularity in spinal surgery recently. Robotic assistance provides higher effectiveness and safety especially in conditions of complicated anatomy. It also enables the novel, previously unavailable surgical techniques, such as GO-Lif for lumbar spine fusion. The aim of the study is to assess the applicability and effectiveness of the robotic assistance in surgical treatment of degenerative lesion of lumbar spine. 16 patients were operated with robotic assistance device (SpineAssist; MAZOR Surgical Technologies, Caesarea, Israel) between August 2009 and February 2010 in Spinal Department of Burdenko Neurosurgical Institute (Moscow, Russia) with degenerative disc disease. Preoperative assessment included MRI, X-rays and high-resolution CT (slice < 1 mm). The CT is essential for preoperative planning using computed work station SpineAssist. The robot was utilized for automated intraoperative positioning of the instruments according to preoperatively planned trajectories. Basic parameters of surgeries were thoroughly recorded: overall surgery time, radiation dose (all manipulations were performed under fluoroscopic control), accuracy of screw placement relative to preoperative planning, which was assessed using postoperative high-resolution CT with 3D reconstruction. Particular interest of the study was focused on the novel fusion technique for lumbar spine: Go-Lif (Guided Oblique Lumbar Interbody Fusion). This fusion modality enables segment fixation with two screws only, it is comparable with pedicular screws in terms of stability, being far less invasive. It may be used standalone or together with TLIF techniques. Robotic assistance enabled optimal screw placement even in complex anatomical cases (thin pedicles and rotational deformity). No implant-related complications were recorded. Surgery time was much longer in first 2 cases, though in further it decreased nearly to conventional (without robot) surgery time. For radiation dose same tendency was observed--in first 2 cases all surgical steps were fluoroscopically controlled, in further cases--only for primary anatomy registration. Based on control CT, accuracy of implant placement with robotic assistance is 1 mm.     

Robotics in spine surgery: A systematic review

Robotic systems to assist with pedicle screw placement have recently emerged in the field of spine surgery. Here, the authors systematically reviewed the literature for evidence of these robotic systems and their utility. Thirty-four studies that reported the use of spinal instrumentation with robotic assistance and met inclusion criteria were identified. The outcome measures gathered included: pedicle screw accuracy, indications for surgery, rates of conversion to an alternative surgical method, radiation exposure, and learning curve. In our search there were five different robotic systems identified. All studies reported accuracy and the most commonly used accuracy grading scale was the Gertzbein Robbins scale (GRS). Accuracy of clinically acceptable pedicle screws, defined as < 2 mm cortical breech, ranged from 80% to 100%. Many studies categorized indications for robotic surgery with the most common being degenerative entities. Some studies reported rates of conversion from robotic assistance to manual instrumentation due to many reasons, with robotic failure as the most common. Radiation exposure data revealed a majority of studies reported less radiation using robotic systems. Studies looking at a learning curve effect with surgeon use of robotic assistance were not consistent across the literature. Robotic systems for assistance in spine surgery have continued to improve and the accuracy of pedicle screw placement remains superior when compared to free-hand technique, however rates of manual conversion are significant. Currently, these systems are successfully employed in various pathological entities where trained spine surgeons can be safe and accurate regardless of robotic training.     

Fijación lumbar posterior empleando el sistema de imagen quirúrgica O-arm: experiencia inicial

ObjectThe use of transpedicular screw fixation has been widely accepted for the treatment of degenerative and traumatic pathology of the lumbar spine. Complications of spinal instrumentation can be serious. Screw misplacement can result in unintended durotomy, nerve root and/or cauda equina injury. In comparison to fluoroscopy-assisted screw placement, computer-assisted image guidance has been shown to achieve overall higher rates of accuracy. The O-arm is able to obtain computed tomography (CT)-type images with multiplanar reconstruction. In this study we evaluated a cohort of patients who underwent posterior lumbar fusion with pedicle screws utilizing the O-arm imaging system.MethodsA retrospective review of 40 consecutive patients who underwent posterior lumbar fusion surgery with O-arm utilization, was performed. The study population included 14 males and 26 females. Age range was 39-85 years with an average of 63.8 years. Twenty one patients had degenerative lumbar stenosis (52.5%) and 19 had spondylolisthesis (47.5%). Intraoperative CT-images were obtained. The mean time for surgery and screw placement was assessed.ResultsA total of 252 pedicle screws were sited using O-arm navigation system, with a mean of 6.3 screws per patient (range 4-10). On the basis of intraoperative CT, 3 screws were redirected, representing a 98.81% accuracy rate.The mean duration of surgery was 157.2 (90-240) minutes and the mean time for screw placement was 7.13 (3.08-15) minutes per screw.Three patients (7.5%) developed superficial wound infections which were treated conservatively. No patients required a return to the operating room because of screw malposition.ConclusionThe use of intraoperative O-arm imaging system with computer-assisted navigation significantly increases the surgical accuracy and safety of pedicle screw placement in lumbar fusion surgery.     

术中CT辅助下椎弓根螺钉置入的精确性和安全性评估

目的 评估术中CT辅助下椎弓根固定技术的安全性和准确性。方法 回顾性分析2014年5月至2015年5月术中CT辅助下椎弓根固定手术治疗的39例脊柱脊髓疾病患者的临床资料,其中脊柱脊髓损伤6例,颅颈交界区畸形6例,脊柱退行性变14例,脊柱脊髓肿瘤13例;术后应用Gertzbein-Robbins分级评价螺钉植入的精确性。结果 椎弓根螺钉固定总数为112枚,术中根据CT影像进行位置修正的螺钉共38枚;其中脊柱脊髓损伤23枚,颅颈交界区畸形8枚,脊柱退行性变40枚,脊柱脊髓肿瘤41枚;颈椎 23枚,胸椎48枚,腰椎41枚。根据Gertzbein-Robbins分级0级105枚,1级5枚,2级2枚。术后发生切口感染4例、脑脊液漏2例、神经损伤1例,未发生与螺钉植入直接相关的并发症,也无二次翻修病例。结论 术中CT能够帮助术者在术中发现位置不良的椎弓根螺钉并对其进行修正,提高椎弓根螺钉植入固定术的精确性和安全性。     

Pedicle Screw Placement in the Thoracolumbar Spine Using a Novel,Simple, Safe,and Effective Guide-Pin : A Computerized Tomography Analysis

ObjectiveTo improve pedicle screw placement accuracy with minimal radiation and low cost, we developed specially designed K-wire with a marker. To evaluate the accuracy of thoracolumbar pedicle screws placed using the novel guide-pin and portable X-rays.MethodsObservational cohort study with computerized tomography (CT) analysis of in vivo and in vitro pedicle screw placement. Postoperative CT scans of 183 titanium pedicle screws (85 lumbar and 98 thoracic from T1 to L5) placed into 2 cadavers and 18 patients were assessed. A specially designed guide-pin with a marker was inserted into the pedicle to identify the correct starting point (2 mm lateral to the center of the pedicle) and aiming point (center of the pedicle isthmus) in posteroanterior and lateral X-rays. After radiographically confirming the exact starting and aiming points desired, a gearshift was inserted into the pedicle from the starting point into the vertebral body through the center of pedicle isthmus.ResultsNinety-nine percent (181/183) of screws were contained within the pedicle (total 183 pedicle screws : 98 thoracic pedicle screws and 85 lumbar screws). Only two of 183 (1.0%) thoracic pedicle screws demonstrated breach (1 lateral in a patient and 1 medial in a cadaver specimen). None of the pedicle breaches were associated with neurologic or other clinical sequelae.ConclusionA simple, specially designed guide-pin with portable X-rays can provide correct starting and aiming points and allows for accurate pedicle screw placement without preoperative CT scan and intraoperative fluoroscopic assistance.     

计算机导航辅助椎弓根螺钉固定的临床研究

目的椎弓根螺钉固定是脊柱病变切除后稳定性重建的标准方法。常规术中透视监测行颈胸节段椎弓根螺钉固定具有相当挑战性,本文旨在就计算机导航辅助椎弓根螺钉固定技术进行初步分析。方法2005年1月至2006年3月在计算机导航系统辅助下,对21例患者（年龄17～63岁,平均43．4岁）共行102枚椎弓根螺钉固定。术前采用0．75mm薄层螺旋CT数据扫描并导入计算机工作站进行脊柱三维重建;术中进行工具注册和匹配后对椎弓根螺钉固定进行实时显示。术后所有病例均采用CT和X线平片随访监测效果。结果手术顺利,螺钉大小选择合适,102枚椎弓根螺钉中100枚螺钉（98%）固定位置及方向准确,2枚椎弓根螺钉突破椎弓根外壁距离小于2mm。所有操作均未发生血管和神经损伤并发症。术中透视次数及手术室人员所受X线辐射量明显减少。结论计算机导航辅助椎弓根螺钉固定是一项安全的手术,且手术精度高。     

Posterior thoracic segmental pedicle screw instrumentation: evolving methods of safe and effective placement

The use of pedicle screw instrumentation in the spine has evolved over the last two decades. The initial use of pedicle screws began in the lumbar spine. As surgeons have become more comfortable with the complex anatomy required for accurate screw placement, the use of pedicle instrumentation has evolved to include their use in the thoracolumbar and thoracic spine. The impetus behind their increased use is a result of the many advantages that pedicle screw anchorage offers over traditional hook and rod constructs. Improved deformity correction and overall construct rigidity are two important advantages of pedicle screw instrumentation due its three-column control over the spinal elements. First, pedicle screw instrumentation obviates the need to place instrumentation within the spinal canal with its inherent risk of neurologic injury. Second, the placement of pedicle screws is independent of facet or laminar integrity and thus has been extremely useful in traumatic, neoplastic, and degenerative conditions. The benefits of pedicle screws in the thoracic spine has been tempered by the potential for catastrophic neurological or soft tissue injuries due to the close proximity of these structures. The narrow and inconsistent shape of the thoracic pedicles, especially in spinal deformity, makes their placement technically challenging. As a result, surgeons have employed a number of techniques to ensure the safe and efficacious placement of thoracic pedicle screws. Detailed anatomic landmarks used to determine pedicle location, intraoperative imaging including navigation, and neurophysiological monitoring are some of the techniques currently used by surgeons. The implementation of these techniques and a thorough understanding of the complex three-dimensional anatomy have allowed surgeons to successfully place thoracic and thoracolumbar pedicle screws.     

Application study of three-dimensional printed navigation template between traditional and novel cortical bone trajectory on osteoporosis lumbar spine

To investigate the safety, accuracy and indications of traditional and novel cortical bone screws placement for osteoporosis lumbar spine, 4 lumbar vertebra specimens (2 males and 2 females) were used for this study. After the computed tomography scanning data of the above anatomical specimens were three-dimensional (3D) reconstructed, one side of each anatomical specimen was randomly chosen to place traditional cortical bone screws, and the other side received novel technical placement. The safety screw trajectory was designed, and a 3D navigation template complementary to the surface anatomical structure of lumbar isthmus lateral margin-vertebral plate-spinous process part was established. The designed supporting navigation template was substantialized, and the navigation template replicated different cortical bone screw trajectory at different sides of the same one lumbar vertebra. Forty cortical bone screws were firstly placed in 3D printed vertebra and then 40 were placed in real anatomical specimens. In 3D printed specimens, the success rates of screw placement with navigation template using traditional and novel techniques were both 100%. While in anatomical specimens, the success rate of screw placement using traditional and novel navigation template was 97.5% (one out of 40 went wrong). Therefore, it is safe, accurate and reliable to place traditional and novel cortical bone screws on osteoporosis lumbar spine using 3D printed navigation template. Traditional and novel screw placement methods should be flexibly applied or combined according to specific sequence and form of vertebra.     

Application of different thresholds for instrumentation device testing in minimally invasive lumbosacral spine fixation

The main aim of this study was evaluating the reliability of stimulus-evoked electromyography (using different thresholds for stimulation of the instrumentation devices) for minimally invasive pedicle screw placement in the lumbosacral spine. A threshold of 5 mA was applied for the pedicle access needle. 7 mA was applied for the tapscrew and pedicle screw stimulation. The existence of threshold differences between vertebral levels was also assessed. All patients underwent postoperative computed tomography (CT) to determine the accuracy of pedicle screw placement. A total of 172 percutaneous pedicle screws were placed in 52 patients. 94.1% of screws were placed at L4, L5 and S1 vertebral levels. No statistically significant differences existed in thresholds of the pedicle access needles, tapscrews and pedicle screws between vertebral levels. In four instances, the pedicle access needle stimulation had a threshold of 5 mA (no breaches were associated). In the rest of occasions, the pedicle access needles had stimulation thresholds above 5 mA. In all instances, tapscrew and pedicle screw thresholds were above 7 mA; the tapscrews and pedicle screws had significantly greater thresholds than the pedicle access needles. No statistically significant differences existed in thresholds between tapscrews and pedicle screws. Postoperative CT imaging revealed one lateral pedicle violation. Both breach rate and false negative rate were 0.5%. No false positive cases were observed. No patients experienced postoperative pedicle screw–related neurologic deficits. A threshold of 5 mA for the pedicle access needle stimulation seems to be safe. Greater than 7 mA should be used for the tapscrew and pedicle screw stimulation.     

胸腰椎椎弓根螺钉置入位置不当19例分析☆

目的：分析胸腰椎椎弓根螺钉置入位置不当的原因。 方法：选择2002-01/2008-01南京中医药大学无锡附属医院骨科收治的经影像学证实的胸腰椎椎弓根螺钉置入位置不当患者19例,男12例,女7例;年龄23~68岁,平均52.5岁。其中胸腰椎骨折5例,腰椎滑脱症8例,退行性腰椎疾病6例。椎弓根固定系统：Steffee 4例,DRFS 3例,RF 6例,AF 4例,GSS 2例。所有病例均经X射线正侧位平片及经椎弓根平面CT薄层扫描观察椎弓根螺钉位置,包括螺钉与椎弓根及硬膜囊,周围大血管的解剖位置关系。 结果：患者自螺钉置入后至发现椎弓根螺钉误置时间为5~69 d,平均18.5 d。其中螺钉穿破椎弓根外侧皮质7例,穿破椎弓根内侧皮质4例,螺钉穿破椎弓根皮质(脊柱侧弯伴旋转)2例,螺钉置入过深2例,螺钉进入椎间孔2例,进入椎间隙2例。 结论：螺钉置入不当的原因与对局部解剖变异及操作技术有关,提高手术技巧、术前术中影像学的测量及监控是正确置钉的关键。