Localization of the trunk muscles using musculoskeletal ultrasound guidance for pedicle screw stimulation during spine surgery

The precise placement of recording electrodes at the relevant myotome is mandatory while performing pedicle screw stimulation (PSS) during spine surgery; however, their placement at trunk muscles is challenging. This study aimed to determine whether ultrasound guidance is useful for trunk muscle localization for PSS during spine surgery. A retrospective clinical study was conducted from a prospective database. Eighty-four patients eligible for spine surgery were recruited. Ultrasound was used to localize the intercostal, rectus abdominis, and internal oblique and psoas muscles if pedicle screw placement was performed at T3 to L1. After the operation, patients were examined for any new neurological deficits related to this procedure, and computed tomography was performed to check screw position if indicated. Four to 22 pedicle screws were used for spinal fixation. The threshold of stimulus to obtain a compound muscle action potential ranged from 1.29 to >20 mA during PSS. Six of our patients sustained new postoperative deficits, and only one case was related directly to pedicel screw misplacement. Loss of motor evoked potential (MEP) over both the lower limbs was noted during pedicle screw placement, and the stimulus threshold during PSS were 1.29 mA at the left T9 and 3.8 mA at the right T5 level. MEP remained absent at the end of surgery despite removal of those two screws. The patient woke with significant weakness in both lower limbs (muscle power 0/0) and voiding difficulty. Fortunately, he regained walking ability 4.5 months later after intensive rehabilitation therapy.     

Focal hole versus screw stimulation to prevent false negative results in detecting pedicle breaches during spinal instrumentation

ObjectiveWe describe a stimulus-evoked EMG approach to minimize false negative results in detecting pedicle breaches during lumbosacral spinal instrumentation.MethodsIn 36 patients receiving 176 lumbosacral pedicle screws, EMG threshold to nerve root activation was determined using a focal probe inserted into the pilot hole at a depth, customized to the individual patients, suitable to position the stimulating tip at the point closest to the tested nerve root. Threshold to screw stimulation was also determined.ResultsMean EMG thresholds in 161 correctly fashioned pedicle instrumentations were 7.5 mA ± 2.46 after focal hole stimulation and 21.8 mA ± 6.8 after screw stimulation. Direct comparison between both thresholds in individual pedicles showed that screw stimulation was always biased by an unpredictable leakage of the stimulating current ranging from 10 to 90%. False negative results were never observed with hole stimulation but this was not true with screw stimulation.ConclusionsFocal hole stimulation, unlike screw stimulation, approaches absolute EMG threshold as shown by the lower normal limit (2.6 mA; p < 0.05) that borders the upper limit of threshold to direct activation of the exposed root.SignificanceThe technique provides an early warning of a possible pedicle breakthrough before insertion of the more harmful, larger and threaded screw.     

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。     

Accuracy of Pedicle Screw Insertion Using Fluoroscopy-Based Navigation-Assisted Surgery : Computed Tomography Postoperative Assessment in 96 Consecutive Patients

Objective

Two-dimensional fluoroscopy-based computerized navigation for the placement of pedicle screws offers the advantage of using stored patient-specific imaging data in providing real-time guidance during screw placement. The study aimed to describe the accuracy and reliability of a fluoroscopy-based navigation system for pedicle screw insertion.

Methods

A total of 477 pedicle screws were inserted in the lower back of 96 consecutive patients between October 2007 and June 2012 using fluoroscopy-based computer-assisted surgery. The accuracy of screw placement was evaluated using a sophisticated computed tomography protocol.

Results

Of the 477 pedicle screws, 461 (96.7%) were judged to be inserted correctly. Frank screw misplacement [16 screws (3.3%)] was observed in 15 patients. Of these, 8 were classified as minimally misplaced (≤2 mm); 3, as moderately misplaced (2.1-4 mm); and 5, as severely misplaced (>4 mm). No complications, including nerve root injury, cerebrospinal fluid leakage, or internal organ injury, were observed in any of the patients.

Conclusion

The accuracy of pedicle screw placement using a fluoroscopy-based computer navigation system was observed to be superior to that obtained with conventional techniques.     

Design and application of a novel patient-specific 3D printed drill navigational guiding template in percutaneous thoracolumbar pedicle screw fixation: A cadaveric study

The conventional surgical method of percutaneous pedicle screw fixation (PPSF) mainly uses X-ray fluoroscopy guidance to target the vertebral pedicle for screw placement. This study aimed to explore the feasibility of establishing a personalized drill guide template for PPSF based on a three-dimensional (3D) printing technique and to evaluate the accuracy and safety of the method for assisting screw insertion in cadaveric specimens. The T3-L3 trunk cadaveric specimens from six adults were subject to a computed tomography (CT) scan in the prone position. A three-dimensional model containing the back skin contour was reconstructed. A bilateral ideal pedicle screw in the T6-L1 segment was designed. Then, the reverse templates were designed. The two templates were fused and printed into an individualized guide template. PPSF was performed under the assistance of the guide template, and the CT scan was taken postoperatively to access the screw position. Ninety-six pedicle screws were successfully placed on the bilateral vertebral body of the T6-L1 segment with the assistance of a guide template. The guide plate was not loosened or displaced when operated by a single hand, and the operation time was 24.6 ± 7.9 s. The axial CT images after puncture indicated that in 96 puncture needles, 90 needles were grade I and 6 were grade II, with a puncture accuracy rate of 98.6%. In conclusion, an individualized PPSF navigation template was developed using Mimics software and 3D printing prototyping, which improved the accuracy of PPSF in cadaveric specimens.     

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.     

神经外科手术机器人置入椎弓根螺钉的精准性

目的 探讨神经外科手术机器人在人体腰椎模型进行椎弓根螺钉置入的精准性.方法 利用0型臂影像系统对模型进行正侧位扫描,并三维重建,获取3D-CT数据,传入手术机器人系统,规划椎弓根螺钉的最佳进钉点和进钉方向.手术机器人系统利用3D-CT数据自动注册后,置入椎弓根螺钉.应用置钉前后的3D融合图像,按照Gertzbein-R...     

Significance of Preoperative Prone Position Computed Tomography in Free Hand Subaxial Cervical Pedicular Screwing

ObjectiveThe subaxial cervical pedicle screwing technique shows powerful biomechanical properties for posterior cervical fusion. When applying a pedicle screw using the freehand technique, it is essential to analyse cervical computed tomography and plan the surgery accordingly. Normal cervical computed tomography is usually performed in the supine position, whereas during surgery, the patient lies in a prone position. This fact leads us to suppose that radiological evaluations may yield misleading results. Our study aimed to investigate whether there is any superiority between preoperative preparation on computed tomography performed in the prone position and that performed in the supine position. MethodsThis study included 17 patients (132 pedicle screws) who were recently operated on with cervical vertebral computed tomography in the prone position and 17 patients (136 pedicle screws) who were operated on by conventional cervical vertebral computed tomography as the control group. The patients in both groups were compared in terms of age, gender, pathological diagnosis, screw malposition and complications. A screw malposition evaluation was made according to the Gertzbein-Robbins scale. ResultsNo statistically significant difference was observed between the two groups regarding age, gender and pathological diagnosis. The screw malposition rate (from 11.1% to 6.9%, p<0.05), mean malposition distance (from 2.18 mm to 1.86 mm, p <0.05), and complications statistically significantly decreased in the prone position computed tomography group. ConclusionPreoperative surgical planning by performing cervical vertebral computed tomography in the prone position reduces screw malposition and complications. Our surgical success increased with a simple modification that can be applied by all clinicians without creating additional radiation exposure or additional costs.     

Image-guided pedicle screws using intraoperative cone-beam CT and navigation. A cost-effectiveness study

Image-guided surgery using intraoperative cone-beam CT and navigation improves screw placement accuracy rates. However, this technology is associated with high acquisition costs. The aim of this study is to evaluate the costs of revision surgery from symptomatic pedicle screw malposition to justify whether the costs of acquiring intraoperative navigation justify the expected benefits. This is a retrospective cost-effectiveness analysis of consecutive patients who had pedicle screw instrumentation using intraoperative cone-beam CT and navigation compared with patients who underwent freehand pedicle screw instrumentation at our institution over 4 years. The costs associated with revision surgery for symptomatic pedicle screw malposition (excess length of stay, intensive care, theatre time, implants and additional outpatient appointments) were calculated. A total of 19 patients had symptomatic screw malpositioning requiring revision surgery. None of these patients had screws inserted under navigation. Revision surgery accounted for an extra 304 bed days and an additional 97 h theatre time. The total extra spent over 4 years was £464,038. When compared to the costs of revision surgery for screw malpositioning, it was cost neutral to acquire and maintain this technology. Intraoperative image-guided surgery reduces reoperation rates for symptomatic screw malposition and is cost-effective in high volume centers with improved patients outcomes. High acquisition and maintenance cost of such technologies is economically justifiable.     

Routine spinal navigation for thoraco–lumbar pedicle screw insertion using the O-arm three-dimensional imaging system improves placement accuracy

Modern image-guided spinal navigation employs high-quality intra-operative three dimensional (3D) images to improve the accuracy of spinal surgery. This study aimed to assess the accuracy of thoraco-lumbar pedicle screw insertion using the O-arm (Breakaway Imaging, LLC, Littleton, MA, USA) 3D imaging system. Ninety-two patients underwent insertion of thoraco–lumbar pedicle screws guided by O-arm navigation over a 27 month period. Intra-operative scans were retrospectively reviewed for pedicle breach. The operative time of patients where O-arm navigation was used was compared to a matched control group where fluoroscopy was used. A total of 467 pedicle screws were inserted. Four hundred and forty-five screws (95.3%) were placed within the pedicle without any breach (Gertzbein classification grade 0). Sixteen screws (3.4%) had a pedicle breach of less than 2 mm (Gertzbein classification grade 1), and six screws (1.3%) had a pedicle breach between 2 mm and 4 mm (Gertzbein classification grade 2). The grade 2 screws were revised intra-operatively. There was no incidence of neurovascular injury in this series of patients. The mean operative time for O-arm patients was 5.25 hours. In a matched control group of fluoroscopy patients, the mean operative time was 4.75 hours. The difference in the mean operative time between the two groups was not statistically significant (p = 0.15, paired t-test). Stereotactic navigation based on intra-operative O-arm 3D imaging resulted in high accuracy in thoraco–lumbar pedicle screw insertion.     

Pilot study of oblique lumbar interbody fusion using mobile percutaneous pedicle screw and validation by a three-dimensional finite element assessment

The purpose of this study was to try oblique lateral interbody fusion (OLIF) using percutaneous pedicle screws (PPS) with mobility.Twelve patients who underwent single-level OLIF were observed for at least one year. These included 6 patients with conventional PPS (rigid group), and 6 with movable PPS (semi-rigid group). Mobile PPS used cosmicMIA, which is a load sharing system. The anterior and posterior disc height, screw loosening and bone healing period, and implant failure were evaluated at final observation by CT. Moreover, the stress on the vertebral body-cage, on the vertebral body-screw/rod and on the bone around the screw was estimated using a three-dimensional finite element assessment in both groups.There was no significant difference in surgical time, amount of bleeding, JOA score, or low back pain VAS between groups. There were no differences between groups in anterior and posterior disc height, screw loosening, and implant failure at final observation. The bone healing period was significantly shorter in the semi-rigid screw group (18.3 months vs 4.8 months, p = 0.01). The finite element analysis showed that the lower stress on the rod/screw would contribute to fewer implant fractures and that lower stress on the bone around the screw would reduce screw loosening, and that higher compressive force on the cage would promotes bone healing.OLIF combined with a movable screw accelerated bone healing by nearly 75%. We conclude that mobile PPS in combination with OLIF promotes bone healing and can be a better vertebral fusion technique.     

Instrumentation Report An endoscopic pedicle probe: Preliminary development

Abstract

Insertion ofpedicle screws in the thoracolumbar spine can be challenging. Incorrect placement can lead to a failure. of fusion or to significant neurologic morbidity. Recently, techniques utilizing intraoperative monitoring and stereotaxis have been developed to achieve proper screw placement. While these techniques may be accurate, they are expensive and may reqLiire additional operating room personnel. We have developed an endoscopic pedicle probe for placement of pedicle screws that may overcome some of these limitations. A small 1.2 mm endoscope was adapted to fit within a hollow pedicle probe. Irrigation was provided via a separate channel within the endoscope. Images from the probe were displayed. both 6n a monitor screen and on a heads up display. The endoscopic pfobe was used to probe 3.6 sawbqne andc22 cadaver thoracolumbar pedicles. After cannulation each specimen was examined to assess Sanvisualized pedicle perforation. In sawbones, perforation was visualized endoscopically in 3 pedicles (8%) with no further perforations found on later direct examination. In cadavers the corticar ca(1cellous interface Was adequately visualized and no perforations occurred. These preliminary results suggest that the endoscopic probe may have utility in the placement of thoracolumbar pedicle screws. [Neurol Res 1997; 19: 657-661]     

True accuracy of percutaneous pedicle screw placement in thoracic and lumbar spinal fixation with a CT-based navigation system: Intraoperative and postoperative assessment of 763 percutaneous pedicle screws

PurposeTo investigate intraoperative reinsertion of percutaneous pedicle screw (PPS) with intraoperative CT-based navigation and to evaluate the rate of deviation of PPS at postoperative radiographic examination.MethodsSeven hundred sixty-three screws were inserted in 138 patients. We investigated the rate of occurrence of intraoperative PPS reinsertion after the diagnosis of screw deviation by fluoroscopy and the causes of each screw deviation. The subsequent distribution of PPS deviation was evaluated by postoperative CT. We also assess the difference in variance between the group judged to be PPS misplaced intra-/postoperatively (IOD group/POD group) and appropriate PPS placement (ND group).ResultsAmong all the screws inserted, 10 (1.3%) were diagnosed as being deviated by fluoroscopy during surgery, and 74 (9.7%) screws were found to be deviated at postoperative CT evaluation. We found more pedicle screw mismatch in the POD group than in the ND group (52.7 vs 11.0%, P < 0.001). The distance between the screw and the reference was greater in the IOD group than that in the ND group (1.4 ± 1.2 vs 2.4 ± 1.1 vertebral levels, P = 0.016). In one patient in the IOD group, a motor function deficit was observed postoperatively.ConclusionPPS fixation under intraoperative CT-based navigation did not prevent screw deviation completely. It is necessary to consider errors that occur during surgery and to confirm placement with real-time assistance such as fluoroscopy even in a surgery performed under CT navigation 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。     

神经导航在脊柱固定手术中的应用

目的：探讨应用神经导航系统进行椎弓根螺钉植入的优越性及近期疗效。方法在神经导航辅助下,对17例病人植入76枚椎弓根螺钉,记录单个椎体注册时间、钉道准备时间、术中出血量、术中“C”型臂照射次数、导航精度、术中螺钉重植次数及术后并发症;术后行CT检查评价椎弓根螺钉位置。结果平均单个椎体注册时间（6.3±2.1） min,平均钉道准备时间（2.6±1.3） min,平均术中出血量（253±70） ml;平均“C”型臂照射次数（3.5±0.5）;平均导航精度（0.9±0.1） mm。根据Richter法评估螺钉植入位置：优70枚,良5枚,差1枚;优良率98.68%。术中重植螺钉4枚,重植率5.26%。10例病人随访3～7个月,均无明显神经系统阳性体征。结论在神经导航辅助下,术者可以实时监测螺钉植入过程,前瞻性地判断植入椎弓根螺钉的大小、位置,使椎弓根螺钉植入有较高的准确性和安全性。     

神经导航技术在脊柱固定手术中的应用(附16例报告)

目的探索使用神经导航技术进行脊柱内固定。方法在神经导航辅助下,对16例患者置入70根椎弓根(侧块)螺钉。通过术后X线摄片核实椎弓根螺钉置入的准确性。结果置入的70根椎弓根(侧块)螺钉长度和直径选择合适,其中68根(97·1%)固定位置及方向准确;早期曾有1根穿出至椎体前方(<1mm),未作处理;1根穿出至椎间盘,经翻修后固定情况良好。无神经和血管损伤症状。结论使用神经导航技术,可以前瞻性地判断置入椎弓根(侧块)钉的大小、位置,实时监测置入过程,提高置入的准确性和安全性。术中脊柱影像三维重建及注册配准对神经导航的准确性有较大影响。     

Accuracy and safety of cortical bone trajectory screw placement by an inexperienced surgeon using 3D patient-specific guides for transforaminal lumbar interbody fusion

Cortical bone trajectory (CBT) is an alternative method for pedicle screw insertion. However, identification of the optimal entry point and the direction of the CBT can be challenging for less-experienced surgeons. The purpose of this study was to evaluate the accuracy of the CBT screw placement by an inexperienced surgeon using a three-dimensional (3D) patient-specific guide for transforaminal lumbar interbody fusion (TLIF). Retrospective analysis of the data pertaining to 30 patients (128 screws) who underwent TLIF with CBT by an inexperienced surgeon using a 3D patient-specific guide (MySpine MC, Medacta) at a single center was performed. The accuracy of the CBT screw was graded into four groups (no perforation; Grade A, 0–2 mm; Grade B, 2–4 mm; and Grade C, > 4 mm). The accuracy of the CBT screw placement was 91% (116/128). Out of the 12 misplaced screws, Grade A was observed in 7 screws (5%), Grade B was observed in 3 screws (2%), and Grade C was observed in 2 screws (2%). There were no cases of medial pedicle wall perforation. The mean screw size was 5.95 ± 0.34 mm in diameter and 40.15 ± 2.83 mm in length. Note that, the accuracy of the CBT screws increased to 97% (83/86) over the first10 cases. Preoperative planning and 3D patient-specific guide enabled the use of longer and thicker screws and an optimal entry point. These results suggest the possibility of efficacy and safety in using 3D patient-specific guides for CBT screw placement by an inexperienced surgeon.     

Virtual reality spine surgery simulation: an empirical study of its usefulness

Abstract

Objective:

This study explores the usefulness of virtual simulation training for learning to place pedicle screws in the lumbar spine.

Methods:

Twenty-six senior medical students anonymously participated and were randomized into two groups (A?=?no simulation; B?=?simulation). Both groups were given 15 minutes to place two pedicle screws in a sawbones model. Students in Group A underwent traditional visual/verbal instruction whereas students in Group B underwent training on pedicle screw placement in the ImmersiveTouch^® simulator. The students in both groups then placed two pedicle screws each in a lumbar sawbones models that underwent triplanar thin slice computerized tomography and subsequent analysis based on coronal entry point, axial and sagittal deviations, length error, and pedicle breach. The average number of errors per screw was calculated for each group. Semi-parametric regression analysis for clustered data was used with generalized estimating equations accommodating a negative binomial distribution to determine any statistical difference of significance.

Results:

A total of 52 pedicle screws were analyzed. The reduction in the average number of errors per screw after a single session of simulation training was 53·7% (P = 0·0067). The average number of errors per screw in the simulation group was 0·96 versus 2·08 in the non-simulation group. The simulation group outperformed the non-simulation group in all variables measured. The three most benefited measured variables were length error (86·7%), coronal error (71·4%), and pedicle breach (66·7%).

Conclusions:

Computer-based simulation appears to be a valuable teaching tool for non-experts in a highly technical procedural task such as pedicle screw placement that involves sequential learning, depth perception, and understanding triplanar anatomy.     

Cervical Pedicle Screw Insertion Using the Technique with Direct Exposure of the Pedicle by Laminoforaminotomy

Objective

To present the accuracy and safety of cervical pedicle screw insertion using the technique with direct exposure of the pedicle by laminoforaminotomy.

Methods

We retrospectively reviewed 12 consecutive patients. A total of 104 subaxial cervical pedicle screws in 12 patients had been inserted. We also assessed the clinical and radiological outcomes and analyzed the direction and grade of pedicle perforation (grade 0: no perforation, 1: <25%, 2: 20% to 50%, 3: >50% of screw diameter) on the postoperative vascular-enhanced computed tomography scans. Grade 2 and 3 were considered as incorrect position.

Results

The correct position was found in 95 screws (91.3%); grade 0-75 screws, grade 1-20 screws and the incorrect position in 9 screws (8.7%); grade 2-6 screws, grade 3-3 screws. There was no neurovascular complication related with cervical pedicle screw insertion.

Conclusion

This technique (technique with direct exposure of the pedicle by laminoforaminotomy) could be considered relatively safe and easy method to insert cervical pedicle screw.     

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。