Morphometry of the supra sciatic notch intrailiac implant anchor passage

STUDY DESIGN: Anatomic study of human ilia. OBJECTIVE: To determine the anatomic dimensions influencing intrailiac anchor placement and design. SUMMARY OF BACKGROUND DATA: The development of the Galveston intrailiac implant anchor markedly improved results of spinal instrumentation to the pelvis. Better quantification of the passage dimensions is needed for the design of anatomically specific implants. METHODS: The length and outer diameter of two intrailiac anchor passages were determined from randomly selected, disease-free pairs of ilia from 129 white skeletons belonging to the Hamann-Todd Osteological Collection (Cleveland, OH, Museum of Natural History). RESULTS: Path B, an anchor passage running from the posterior superior iliac spine to the anterior inferior iliac spine, was significantly longer than path A, proceeding from the posterior superior iliac spine to the superior rim of the acetabulum, in adult and teenage males and females. For example, in adult females path B measured 141.2 +/- 7.5 mm versus 124.9 +/- 7.1 mm, P = or < 0.0001. The absolute minimum path A length available for an intrailiac post or screw anchor, following the required posterior superior iliac spine removal, was 80 mm in adults and male teenagers and 70 mm in female teenagers. For path B the hip joint was not at risk, and a safe anchor passage of at least 90 mm in teenagers and 110 mm in adults was available. The minimum thickness of the paths occurred directly above the sciatic notch. It was significantly larger in path A than path B, 20.2 +/- 2.4 mm versus 14.4 +/- 3.2 mm, P < 0.0001. CONCLUSION: Of the two supra sciatic intrailiac paths studied, the path passing from the posterior superior iliac spine toward the anterior inferior iliac spine provided a longer and potentially safer anchor site. These studies suggest techniques for accessing longer anchor paths and the need for larger diameter anchors in order to achieve optimum intra iliac anchor stiffness and strength.     

Percutaneous transiliac pelvic fracture fixation: cadaver feasibility study and preliminary clinical results

BACKGROUND: Insertion of iliosacral lag screws into the S1 vertebral body has been well described in the literature. In situations in which the patient's S1 body morphology precludes the safe use of iliosacral screws, alternative implants have been suggested. The purpose of this study was to evaluate the feasibility of percutaneous transiliac pelvic fracture fixation as a treatment alternative. METHODS: First, three human cadaver torsos were examined to define the fluoroscopic anatomic parameters of the posterior iliac wing. Landmarks were identified to localize the potential initial implant insertion point for safe percutaneous placement of implants posterior to the spinal canal at the level of the posterior superior iliac spine. Next, a series of 10 clinical cases was used for an initial evaluation of a technique based on these findings, employing a cannulated, self-locking, transiliac screw. The pelvic injuries were type C in nine patients (OTA 61-C1 in seven, 61-C2 in one, and 61-C3 in one) and type B (OTA 61-B2) in one. RESULTS: Anatomic dissection of the cadavers with direct measurements and fluoroscopic imaging indicated that a percutaneous technique was feasible for transiliac pelvic fixation. The initial clinical series provided support for the described technique as determined from the cadaver-derived data. In these 10 cases, there were no untoward intraoperative events. Follow-up to union (minimum, 5 months) revealed no hardware failures. CONCLUSIONS: Percutaneous transiliac pelvic fixation is a feasible technique that may be considered by the pelvic surgeon pending further clinical study.     

不同路径髂骨钉钉道的CT影像学研究

目的：研究髂骨钉的最佳路径,为腰骶骨盆重建手术提供参考依据。方法：2009年2月至8月,选门诊或住院因各种原因进行骨盆CT扫描及三维重建并且无阳性表现的50例患者影像学资料进行研究,男28例,女22例;年龄19～65岁,平均41.2岁。设计4条路径,A、B、C路径均以CLIC点（Chiotic线与后髂嵴的交叉点,位于髂后上棘上方24mm处）为起点,方向分别为髋臼上缘、髂前下棘、髋臼中心;D路径以髂后上棘起点,指向髂前下棘。对每条路径中不同钉道的长度及钉道中两处狭窄点的骨板厚度进行数据分析。结果：A（CLIC点到髋臼上缘）、B（CLIC点到髂前下棘）、D（髂后上棘与髂前下棘）路径钉道长度相当,但A路径髂骨板厚度明显较B、D路径大。A、C（CLIC点到髋臼中心）路径髂骨板厚度无明显差异,但A路径通道长度明显大于C路径。结论：A路径即从CLIC点到髋臼上缘方向的髂骨钉钉道路径最长且髂骨板最厚,能够容纳相对最长最粗的髂骨钉,又能承受的拉力最大,是最理想的髂骨钉钉道。     

Screw placement in percutaneous acetabular surgery: gender differences of anatomical landmarks in a cadaveric study

Purpose

Percutaneous reduction and periarticular screw implantation techniques have been successfully introduced in acetabular surgery. The advantages of this less invasive approach are attenuated by higher risks of screw misplacement. Anatomical landmarks are strongly needed to prevent malplacement. This cadaver study was designed to identify reliable anatomical osseous landmarks in the pelvic region for screw placement in acetabular surgery. Gender differences were specifically addressed.

Methods

Twenty-seven embalmed cadaveric hemipelvic specimens (13 male, 14 female) were used. After soft-tissue removal, anterior and posterior column acetabular screw placement was conducted by one orthopaedic trauma surgeon under direct vision. Each column was addressed by antegrade and retrograde screw insertion. Radiographic verification of ideal screw placement was followed by assessment of the distance from the different entry points to adjoining anatomical osseous structures.

Results

For anterior column screw positioning, the posterior superior iliac spine (PSIS), posterior inferior iliac spine (PIIS), iliopectineal eminence and centre of the symphysis were most reliable regarding gender differences. For posterior column screw positioning, the distance to the anterior superior iliac spine (ASIS) and the ischial tuberosity showed the lowest deviation between the different gender specimens. Highest gender differences were seen in relation to the cranial rim of the superior pubic ramus in retrograde anterior column screw positioning (p = 0.002). Most landmarks could be targeted within a 2.5-cm range in all specimens.

Conclusions

The findings emphasise the relevance of osseous landmarks in acetabular surgery. By adhering to easily identifiable structures, screw placement can be safely performed. Significant gender differences must be taken into consideration during preoperative planning.     

Pedicle screw fixation of the C7 vertebra using an anteroposterior fluoroscopic imaging technique

Cervical pedicle screws have been reported to be biomechanically superior to lateral mass screws. However, placement of these implants is a technical challenge. The purpose of this investigation was to use an anatomic and a clinical study to evaluate a technique for placement of the pedicle screws in the C7 vertebra using fluoroscopic imaging in only the anteroposterior (A/P) plane. Ten adult cadaver C7 vertebrae were used to record the pedicle width, inclination and a suitable entry point for placement of pedicle screws. A prospective study of 28 patients undergoing posterior instrumentation of the cervical spine with C7 pedicle screw placement was also performed. A total of 55 C7 pedicle screws were placed using imaging only in the A/P plane with screw trajectory values obtained by the anatomic study. Radiographs and CT scans were performed post-operatively. The average posterior pedicle diameter of C7 vertebra was 9.5 ± 1.2 mm in this study. The average middle pedicle diameter was 7.1 mm and the average anterior pedicle diameter was 9.2 mm. The average transverse pedicle angle was 26.8 on the right and 27.3 on the left. CT scans were obtained on 20 of 28 patients which showed two asymptomatic cortical wall perforations. One screw penetrated the lateral wall of the pedicle and another displayed an anterior vertebral penetration. There were no medial wall perforations. The preliminary results suggest that this technique is safe and suitable for pedicle screw placement in the C7 vertebra.     

Unilaterale trianguläre lumbopelvine Stabilisierung

Operative fixation has become treatment of choice for unstable sacral fractures. Osteosynthesis for these fractures results in loss of reduction in up to 15%. Vertical sacral fractures involving the S1 facet joint (Isler 2 and 3) may lead to multidirectional instability. Multidirectional instability of the posterior pelvic ring and lumbopelvic junction may be stabilized and forces balanced by a so-called lumbopelvic triangular fixation. Lumbopelvic triangular fixation combines vertical fixation between the lumbar vertebral pedicle and the ilium, with horizontal fixation, as an iliosacral screw or a transiliacal plate osteosynthesis. The iliac screw is directed from the posterior superior iliac spine (PSIS) to the anterior inferior iliac spine (AIIS). Thereby, lumbopelvic fixation decreases the load to the sacrum and SI joint and transfers axial loads from the lumbar spine directly onto the ilium. Triangular lumbopelvic fixation allows early full weight bearing and therefore reduces prolonged immobilization. The placement of iliac screws may be a complex surgical procedure. Thus, the technique requires thorough surgical preparation and operative logistics. Wound-related complications may occur. Preexisting Morell–Lavalée lesions increase the risk for infection. Prominent implants cause local irritation and pain. Hardware prominence and pain are markedly reduced with screw head recession into the PSIS.     

Prospective evaluation of thoracic pedicle screw placement using fluoroscopic imaging

BACKGROUND: In this prospective 18-month study, 29 patients underwent posterior thoracic instrumentation with placement of 209 transpedicular screws guided by intraoperative fluoroscopic imaging and anatomic landmarks. We assessed the safety, accuracy, complications, and early stability of this technique. METHODS: Pedicle and pedicle-rib units were measured, and screw cortical penetrations were graded on anatomy and depth of penetration. All 29 patients underwent preoperative computed tomographic (CT) imaging, and 28 underwent postoperative CT imaging (199/209 screws). RESULTS: From T2 to T12, screw diameters were >or=5 mm with mean medial screw angulation measuring 20-25 degree. Of the 209 screws placed from T1 to T12, 111 had diameters greater than or equal to the pedicle width. From T3 to T9, the mean diameter of the pedicle screws exceeded the mean pedicle width. Lateral pedicle wall penetration occurred significantly more often than superior, inferior, and medial pedicle wall penetrations and anterolateral vertebral body penetration. Five of six high-risk screw penetrations occurred in one patient when intraoperative technique was compromised. We observed no new postoperative neurologic deficits, visceral injuries, or pedicle screw instrumentation failures. The three high-risk anterolateral vertebral body penetrations at T1 and T2 were associated with a significantly decreased mean screw transverse angle; the three high-risk medial pedicle wall penetrations occurring from T3 to T9 were associated with a significantly increased mean screw transverse angle. Among all 26 patients available at postoperative follow-up (mean 11.9 months), the mean loss of kyphosis correction was 2.0 degree. CONCLUSIONS: Guided by intraoperative fluoroscopic imaging and anatomic landmarks, thoracic pedicle screws can be placed safely. Early clinical follow-up reveals excellent results with minimal loss of kyphosis correction.     

Galveston固定髂骨钉置入路径的研究

目的 通过成人尸体髂骨形态解剖学及影像学相关数据的测量与分析,探讨Galveston 固定中最理想的髂骨钉置入路径.方法 保存完好的5具10侧新鲜尸体半骨盆,性别不限.于髂骨Chiotic线上方15 mm处每5 mm平行于该线截骨,直至髋臼上缘.分别测量截骨面髂骨钉置入有效路径长度、峡部位置及内径宽度.50例成人患者(性别不限)行骨盆CT三维重建.分别测量Click点至髂前下棘下缘(A)、髂后上棘至髂前下棘下缘(B)、髂后上棘至髋臼上壁(C)三条路径的有效路径长度,以及峡部内径宽度及峡部与进钉点的距离.结果 与尸体髂骨测量结论一致,影像学测量结果示路径A拥有最长的有效路径长度,男性平均(137±8)mm,女性(130±11)mm.经由路径A、B可支持两枚髂骨钉的置入,两路径均允许置入男性长度100 mm,直径8 mm,女性长度80 mm,直径6～7 mm髂骨钉.结论 相对于传统髂骨钉置入路径,Click点至髂前下棘下缘允许更长髂骨钉的置入而穿破髋臼的风险更小,为Galveston固定中髂骨钉置入最理想路径.     

Anatomical risks of using supra-acetabular screws in percutaneous internal fixation of the acetabulum and pelvis

We conducted a study to determine whether a lag screw placed percutaneously at the level of the pelvic brim for treatment of iliac fracture risks injury to the lateral femoral cutaneous nerve (LFCN). A 4-mm Kirschner wire (K-wire) was placed percutaneously into each of 8 human cadaveric hemipelvises (4 pelvises) at the level of the pelvic brim to represent the path of screw placement. Under fluoroscopic guidance, each K-wire was advanced from the anteroinferior iliac spine toward the posterior iliac crest. Cadavers were dissected at study end. Proximity of the LFCN to the percutaneously inserted K-wire was the main outcome measured. In 4 of the 8 hemipelvises, the LFCN was disrupted; in 3 hemipelvises, it was within 4 mm of the K-wire; in the last hemipelvis, it was 23 mm away. LFCNs varied anatomically from 1 to 5 branches; disruptions occurred more in LFCNs with multiple branches than in those with 1 branch. The results suggest considerable risk for injury to the LFCN during percutaneous fixation of iliac and acetabular fractures using a percutaneous screw at the level of the pelvic brim.     

骶髂关节经皮拉力螺钉固定钉道参数的解剖学测量

目的 为经S_1椎弓根水平骶髂关节拉力螺钉固定术提供应用解剖学依据.方法 2008年6月至2009年7月收集50个成人骨盆的螺旋CT扫描数据,重建骨盆三维模型,模拟经皮托力螺钉固定.测量S_1椎弓根的宽和高、骶髂关节拉力螺钉的进针点和进针方向、进针点至S_1椎体对侧前皮质和髂后上棘的距离.结果 S_1椎弓根的宽和高分别为(20.43±1.63)mm和(20.26±0.99)mm;2枚螺钉的进针点均在髂前上棘和髂后上棘的连线上方,至髂后上棘的距离分别为(49.87±6.80)mm和(51.11±7.15)mm.螺钉平行进入S_1椎弓根,与髂骨翼后外侧面垂直,与冠状面和欠状面的夹角分别为18.35°±5.20°和77.62°±3.98°.进针点到S1椎体对侧前皮质的距离分别为(76.08±4.32)mm和(77.62±3.98)mm.骶髂关节拉力螺钉的长度、S_1椎弓根的高度和宽度、进针点到髂后上棘的距离、进针点与冠状面的夹角在男女之间差异有统计学意义(P<0.05).结论 正常成人在S_1椎弓根水平均町置入2枚直径为6.5 mm的拉力螺钉,钉道参数的解剖学测量为骶髂关节拉力螺钉固定手术导航模板的设计提供了理论基础.     

An evaluation of image-guided technologies in the placement of anterior thoracic vertebral body screws in spinal trauma: a cadaver study

BACKGROUND: Image guidance provides additional anatomic information to the surgeon, which may allow more accurate insertion of spinal implants. Imprecise placement of anterior thoracic screws places the spinal cord and paraspinal structures at risk for injury. Image guidance may afford a safety benefit to patients when anterior thoracic screws are required in the setting of spinal stabilization after trauma. OBJECTIVES: To compare the accuracy of anterior thoracic screw placement using standard fluoroscopy, computer-assisted fluoroscopic image guidance, Iso-C3D image guidance, and electromagnetic fluoroscopic image guidance. STUDY DESIGN: A surgical simulation study in human cadaver spine specimens. METHODS: After an open thoracotomy approach, anterior thoracic screws were placed by experienced spine surgeons using 4 different image-guided techniques in 4 human cadaver thoracic spines. Screws were placed in the 9th, 10th, and 11th thoracic vertebrae of each specimen. The specimens were then examined with thin-cut computed tomography (CT) scans, and with sagittal and coronal reconstructions. Measurements included the distance of the screw from the spinal canal, the angle of the screw path in relation to a perpendicular to a line that bisects the spinous process, and the angle of screw divergence from the superior endplate. RESULTS: There was no evidence of spinal canal penetrance with any of the image-guided techniques used to place anterior thoracic vertebral body screws. Screws inserted with standard fluoroscopy tended to aim anterolaterally by 18 degrees. The image-guidance systems allowed more accurate placement of anterior thoracic screws in the transverse plane compared with standard fluoroscopy. There was no statistically significant difference in coronal plane screw angulation (angle of divergence with the superior endplate) between any of the imaging methods. CONCLUSIONS: Spinal image-guidance systems may allow spine surgeons to place anterior thoracic screws more precisely, particularly in the axial plane. The improved accuracy of spinal implant insertion could ultimately provide a benefit to patient safety, especially in the setting of malaligned vertebral bodies after trauma.     

枢椎后路椎板螺钉固定技术的可行性研究

目的:观察和测量国人枢椎椎板以获取形态学参数,探讨枢椎后路椎板螺钉固定的可行性及进针技术.方法:用电子游标卡尺、量角器测量28套正常成年人枢椎新鲜标本的相关参数,包括上位和下位椎板螺钉进针点距椎板上缘距离、枢椎椎板上、中、下部的厚度.枢椎椎板高度、上位和下位椎板螺钉的长度和进针角度、进针点至椎动脉孔及下关节突中心点距离等14项指标.并对测得的数据进行统计学分析.结果:上位和下位椎板螺钉进针点距椎板上缘距离分别为4mm和8 mm,枢椎椎板上、中、下部的厚度分别为3.2、6.7、5.5 mm,椎板高度为12.8mm,上位和下位椎板螺钉的长度分别为26.2mm和25.5mm.结论:枢椎后路椎板螺钉固定技术在国人解剖学上具有可行性,枢椎椎板螺钉固定可作为枢椎后路固定技术的补充.     

The safety of fluoroscopically-assisted thoracic pedicle screw instrumentation for spine trauma

BACKGROUND: Pedicle screw fixation is considered biomechanically superior to other stabilization constructs. However, the potential for severe complications have discouraged its use in the thoracic spine. Our goal is to determine the incidence of major perioperative complications following the placement of thoracic pedicle screws using anatomic landmarks and intraoperative fluoroscopy in patients with spine fractures. METHODS: Retrospective review of 245 consecutive patients with spine fractures requiring pedicle screw fixation between T1 and T10 at a regional Level I trauma center between 1995 and 2001. Database and medical record review were used to identify the incidence of major perioperative complications. A major complication was defined as a potentially life-threatening vascular injury, neurologic deterioration, pneumothorax or hemothorax, and tracheoesophageal injury. Patients were monitored for these complications from the time of surgery until discharge. RESULTS: In all, 1,533 pedicle screws were placed between T1 and T10 in 245 patients. No patient sustained a major complication related to screw placement. Three patients (1.2%) required a secondary procedure for prophylactic revision of four (0.26%) malpositioned screws. CONCLUSIONS: This study supports the safety of pedicle screws in the thoracic spine using preoperative imaging evaluation, standard posterior element landmarks and intraoperative fluoroscopy.     

骶骨侧块在髂骨外板后部投影的临床意义

目的：观察并测量骶骨侧块在髂骨外板后部的投影范围，探讨骶髂螺钉置入的理想区域。方法：在16具尸体骨盆标本上，用克氏针沿着骶骨侧块最外缘自内向外穿过髂骨，根据克氏针在髂骨外板的位置，得到骶骨侧块在髂骨外板的三角形投影。分别测量两侧投影的宽度、高度、投影纵轴到髂后上棘、髂后下棘的距离。结果：骶骨侧块投影的高度为61．4mm，三角形投影的底部宽度为56．8mm，三角形投影的纵轴到髂后上棘和髂后下棘的平均距离分别为30．0mm、27．4mm。结论：骶骨侧块在髂骨外板投影区的上部是骶髂螺钉置入的较佳位置。     

颈椎椎弓根螺钉徒手植入技术的临床研究

目的 评价颈椎椎弓根螺钉徒手植入技术（无须术中影像技术引导）的安全性和可靠性。方法应用Axis内固定系统（美国枢法模公司）对36例颈椎疾病患者进行颈后路经椎弓根内固定术,共植入螺钉144枚,方法如下：①术中清晰地显露颈椎侧块和突间关节,用直径3,0mm高速球形磨钻去除侧块外上象限处骨皮质,然后用2．0mm的自制手锥沿椎弓根事先确定的方向轻轻钻入,若遇阻力则需略改变方向,使其自然置入,深约2～2,5cm。确定无误后,则安置Axis钛板和置入长度合适的椎弓根螺钉。②安装完毕后,即用C型臂X线机作双斜位透视,无误后关闭切口。结果从G～G,共植入根弓根螺钉144枚,其中10枚（6．8％）钉初次置入后感觉松动,经校正后二次置入成功,11枚（3．5％）钉道钻孔后出血较多,但及时处理后出血停止并无不良结果。术后X线斜位片及CT片显示,16枚（11．1％）螺钉穿破椎弓根,其中10枚螺钉（6．9％）穿破椎弓根外侧皮质,4枚（2．8％）穿破椎弓根上侧皮质,2枚（1．3％）穿破椎弓根下侧皮质。随访未发现与螺钉置入穿破椎弓根皮质有关的神经血管损伤问题。结论本研究提示,在事先充分的对每个患者颈椎椎弓根X线及CT解剖结构了解的情况下,徒手置入椎弓根螺钉行颈椎后路内固定安全可行。     

骨盆髂嵴外固定架Schanz钉置钉区域的影像学研究

目的:对骨盆髂嵴外固定架Schanz钉置钉区域进行影像学研究以指导置钉.方法:将筛选出的9例成人正常骨盆的2.0 mm层厚轴向CT扫描结果导入MIMICS 10.0软件.通过后者将髂嵴外固定架Schanz钉置钉区域,即位于髂前上棘及臀中肌结节之间的、髋臼之上的髋臼前柱的高位部分,进行真正矢状面及冠状面重建.然后应用该软件的测量工具于重建面上进行测量,最后对测量结果进行分析.结果:位于髂前上棘前缘后方16.5 mm宽度为49.6 mm的髂嵴节段可用作定位髂嵴外固定架Schanz钉的进钉点.该节段髂嵴所覆盖骨质相对丰厚及纵深,可完全容纳直径为5.0 mm的Schanz钉,并可经髂嵴将该直径的螺钉最浅打入71.7 mm至髋臼顶及最深打入143.5 mm至髋臼后方相对致密的骨质.结论:本研究结果可用于指导髂嵴外固定Schanz钉的置入,于上述进钉点区域将Schanz钉朝向髋臼或其后方打入臼顶或臼后相对致密的骨质以获得较好的把持力从而增强固定效果.     

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.     

改良二维X线导航模拟椎体三维影像引导胸腰段椎弓根钉内固定的临床应用

目的探讨改良二维X线导航模拟椎体三维影像的方式在引导胸腰段椎弓根钉内固定的应用效果。方法对66例胸腰段骨折和腰椎疾病患者行后路椎弓根钉固定撑开复位手术,采用改良二维导航的方法获取手术椎节的正侧位及斜位片,虚拟成椎体的正侧位及椎弓根轴位片,引导椎弓根钉植入术。结果术中共植入280枚椎弓根钉,导航虚拟路径与实际椎弓根钉影像之间的平均位置差为1.5mm,角度平均偏差1.0°。术后CT显示,全部椎弓根钉均位于椎弓根内,未出现涉及或突破皮质的现象;椎弓根钉与椎体纵轴角度平均偏差2.0°。结论采用改良二维X线导航模拟椎体三维影像的方法引导胸腰段椎弓根内固定,提高了置钉的准确性和安全性,简便可行,临床效果显著。