Intraoperative computed tomography-guided navigation versus fluoroscopy for single-position surgery after lateral lumbar interbody fusion

There are no reports comparing fluoroscopy and intraoperative computed tomography (CT) navigation in lateral single-position surgery (SPS) in terms of surgical outcomes or implant-related complications. Therefore, the purpose of this study was to use radiological evaluation to compare the incidence of instrument-related complications in SPS of lateral lumbar interbody fusion (LLIF) using fluoroscopy with that using CT navigation techniques. We evaluated 99 patients who underwent lateral SPS. Twenty-six patients had a percutaneous pedicle screw (PPS) inserted under fluoroscopy (SPS-C group), and 73 patients had a PPS inserted under intraoperative CT navigation (SPS-O group). Average operation time was shorter in the SPS-C group than in the SPS-O group (88.4 ± 24.4 min versus 111.9 ± 35.3 min, respectively, P = 0.003). However, there was no significant difference between the two groups in postoperative thigh symptoms or reoperation rate. The screw insertion angle of the SPS-C group was smaller than that of the SPS-O group, but there was no significant difference in the rate of screw misplacement (4.6% versus 3.4%, respectively, P = 0.556). By contrast, facet joint violation (FJV) was significantly lower in the SPS-O group than in the SPS-C group (8.4% versus 21.3%, respectively, P < 0.001). While fluoroscopy was superior to intraoperative CT navigation in terms of mean surgery time, there was no significant difference in the accuracy of PPS insertion between fluoroscopy and intraoperative CT navigation. The advantage of intraoperative CT navigation over fluoroscopy is that it significantly decreases the occurrence of FJV in SPS.     

Fluoroscopic versus CT-guided cortical bone trajectory pedicle screw fixation: Comparing trajectory related complications

Cortical bone trajectory (CBT) pedicle screw fixation is an emerging technique for treatment of degenerative spine disease which requires either intraoperative fluoroscopy or intraoperative CT guidance (iCT). To date, there has been no direct comparison of these two navigation modalities; here we compare fluoroscopic versus iCT navigation for CBT pedicle screw fixation. We retrospectively reviewed all patients who underwent CBT screw fixation with either fluoroscopic or iCT guidance for lumbar degenerative disease by the senior author. Trajectory-related complications such as medial or lateral breach were compared on postoperative CT, in addition to the incidence of trajectory-related dural tear. We also compared general surgical complications such as postoperative infection and decompression related durotomies. Thirty-eight patients (19 fluoroscopic, 19 CT-guided) who underwent placement of 182 cortical screws (88 fluoroscopic, 94 CT-guided) were identified. In terms of trajectory-related complications, the iCT cohort had fewer medial breaches (1/94) compared to the fluoroscopic cohort (6/88) (p = 0.05). Each group had one lateral breach (p = 0.73). There was one case of CSF leak from screw placement in the fluoroscopic cohort, but none in the iCT cohort (p = 0.48). Overall, there were eight trajectory-related complications in the fluoroscopic cohort versus two in the iCT cohort (p = 0.04). Our data suggests statistically significant decreased trajectory-related complications with iCT-guided CBT screw fixation as compared to fluoroscopically guided. In terms of general surgical complications, while we observed increased postoperative infections in our fluoroscopic cohort, there was no statistically significant difference.     

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.     

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。     

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.     

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。     

Evaluation of the implantation of transpedicular screws in spinal instrumentation with free-hand technique and navigation-assisted with intraoperative computed tomography: An analytical-positional study

BackgroundSpinal instrumentation using transpedicular screws has been used for decades to stabilize the spine. In October 2018, an intraoperative CT system was acquired in the Neurosurgery service of the University Hospital Complex of Vigo, this being the first model of these characteristics in the Spanish Public Health System, so we began a study from January 2015 to December 2019 to assess the precision of the transpedicular screws implanted with this system compared with a control group performed with the classical technique and final fluoroscopic control.MethodsThe study was carried out in patients who required transpedicular instrumentation surgery, in total 655 screws were placed, 339 using the free-hand technique (Group A) and 316 assisted with intraoperative CT navigation (Group B) (p > 0.05). Demographic characteristics, related to surgery and the screw implantation grades were assessed using the Gertzbein–Robbins classification.Results92 patients were evaluated, between 12 and 86 years (average: 57.1 years). 161 thoracic screws (24.6%) and 494 lumbo-sacral screws (75.4%) were implanted. Of the thoracic screws, 33 produced a pedicle rupture. For the lumbo-sacral screws, 71 have had pedicle violation. The overall correct positioning rate for the free-hand group was 72.6% and for the CT group it was 96.5% (p < 0.05).ConclusionThe accuracy rate is higher in thoracic-lumbar instrumentation in the navigation group versus free-hand group with fluoroscopic control.     

Navigated minimally invasive facet fusion during percutaneous lumbar pedicle screw insertion: Technical note

ObjectiveMinimally invasive surgery (MIS), or percutaneous, lumbar pedicle screw placement is commonly done, but the percutaneous nature of this makes posterior arthrodesis extremely difficult. Many times, surgeons will simply forego posterior arthrodesis, place posterior pedicle screws, and rely only on the interbody area for arthrodesis. We describe our technique of adding facet arthrodesis via the same corridor through which the pedicle screw is inserted with minimal addition of time or steps.MethodsWe demonstrate our technique of how we use navigation and tubular retractors to perform posterior facet arthrodesis during percutaneous pedicle screw placement. We illustrate this technique with a case of a patient with scoliosis, intraoperative photos, and an illustrative video. We also show an intraoperative computed tomography image to help visualize the arthrodesis surfaces. With this technique, we show how there are a few additional steps that are not very time consuming to add posterior arthrodesis.ResultsMIS facet fusion can be performed in a relatively straightforward manner during percutaneous pedicle fixation without significant addition of intraoperative time or steps.ConclusionsIt is possible to add posterior arthrodesis to percutaneous lumbar pedicle screw fusion with few added steps and minimal addition of time using navigation and MIS tubular retractors.     

Facet joint violation after single-position versus dual-position lateral interbody fusion and percutaneous pedicle screw fixation: A comparison of two techniques

BackgroundThe purpose of this study was to compare the incidence of facet joint violation (FJV) after placement of percutaneous pedicle screws (PPSs) in 2 cohorts of patients who underwent surgery in a single position or dual position following lateral lumbar interbody fusion (LLIF) (extreme lateral interbody fusion [XLIF]).MethodsWe reviewed 82 patients who underwent combined XLIF surgery and PPS fixation for the treatment of degenerative lumbar spinal disorders. Patient demographics were compared between 2 groups: those who remained in the lateral decubitus position for PPS fixation (SP group) and those who were turned to the prone position (DP group). Postoperative axial computed tomography scans were evaluated independently for FJV according to the following classification: grade 0, no impingement; grade 1, screw head in contact/suspected to be in contact with the facet joint; and grade 2, screw clearly invaded the facet joint.ResultsA total of 349 screws were graded. Using the consensus grades, the incidence of FJV was 13.2% (46/349), but the incidence of FJV did not differ significantly according to the position of the patient during PPS insertion (SP group; 15.4%, DP group; 10.8%, P = 0.204).ConclusionsAlthough the incidence of FJV after PPS insertion did not differ between the prone and lateral decubitus positions, grade 2 FJV was observed only in the SP group. To avoid FJV, the surgeon should pay close attention to the facet joints when inserting PPSs with the patient in a lateral decubitus position.     

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.     

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。     

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.     

The Clinical Experience of Computed Tomographic-Guided Navigation System in C1-2 Spine Instrumentation Surgery

Objective

To identify the accuracy and efficiency of the computed tomographic (CT)-based navigation system on upper cervical instrumentation, particularly C1 lateral mass and C2 pedicle screw fixation compared to previous reports.

Methods

Between May 2005 and March 2014, 25 patients underwent upper cervical instrumentation via a CT-based navigation system. Seven patients were excluded, while 18 patients were involved. There were 13 males and five females; resulting in four degenerative cervical diseases and 14 trauma cases. A CT-based navigation system and lateral fluoroscopy were used during the screw instrumentation procedure. Among the 58 screws inserted as C1-2 screws fixation, their precise positions were evaluated by postoperative CT scans and classified into three categories : in-pedicle, non-critical breach, and critical breach.

Results

Postoperatively, the precise positions of the C1-2 screws fixation were 81.1% (47/58), and 8.6% (5/58) were of non-critical breach, while 10.3% (6/58) were of critical breach. Most (5/6, 83.3%) of the critical breaches and all of non-critical breaches were observed in the C2 pedicle screws and there was only one case of a critical breach among the C1 lateral mass screws. There were three complications (two vertebral artery occlusions and a deep wound infection), but no postoperative instrument-related neurological deteriorations were seen, even in the critical breach cases.

Conclusion

Although CT-based navigation systems can result in a more precise procedure, there are still some problems at the upper cervical spine levels, where the anatomy is highly variable. Even though there were no catastrophic complications, more experience are needed for safer procedure.     

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.     

Pedicle screw placement with use of a navigated surgical drill at subaxial cervical spine

Study designRetrospective cohort study.ObjectiveThis study was performed to evaluate the accuracy of cervical pedicle screw (CPS) placement with use of a navigated surgical drill (ND) and to compare it with navigated manual probe (MP) at C3–C6.Methods47 consecutive patients (27 males and 20 females, 67.2 [33–91] years) underwent a posterior cervical fixation using CPSs under an intraoperative 3D - – CT based navigation system (total 207 CPSs). For initial probing, ND with 2.2-mm steel burr was used since Apr. 2017 (Group ND; 33 patients, 152 CPSs). MP was used earlier (Group MP; 14 patients, 55 CPSs). There were no other different procedures between the two groups. The accuracy of CPS placement was graded with postoperative CT and compared between the two groups.ResultsThere were no significant differences in the total perforation rates both in axial and sagittal planes between Groups ND and MP (axial; 7.2% vs. 14.5%, p = 0.25, sagittal; 10.5% vs. 14.5%, p = 0.46). However, the lateral and rostral perforation rates were significantly reduced in Group ND compared to Group MP (lateral: 36.4% vs. 87.5%, p = 0.04; rostral: 6.3% vs. 100%, p = 0.001).ConclusionAlthough ND did not decrease the total perforation rate significantly, it reduced the incidence of lateral and rostral perforation. ND is likely to make initial probing easier without a forcible manipulation which might cause vertebral rotation.     

Reduction of Radiation Exposure by Modifying Imaging Manner and Fluoroscopic Settings during Percutaneous Pedicle Screw Insertion

ObjectivePercutaneous pedicle screw (PPS) fixation is a needle based procedure that requires fluoroscopic image guidance. Consequently, radiation exposure is inevitable for patients, surgeons, and operation room staff. We hypothesize that reducing the production of radiation emission will result in reduced radiation exposure for everyone in the operation room. Research was performed to evaluate reduction of radiation exposure by modifying imaging manner and mode of radiation source. MethodsA total of 170 patients (680 screws) who underwent fusion surgery with PPS fixation from September 2019 to March 2020 were analyzed in this study. Personal dosimeters (Polimaster Ltd.) were worn at the collar outside a lead apron to measure radiation exposure. Patients were assigned to four groups based on imaging manner of fluoroscopy and radiation modification (pulse mode with reduced dose) : continuous use without radiation modification (group 1, n=34), intermittent use without radiation modification (group 2, n=54), continuous use with radiation modification (group 3, n=26), and intermittent use with radiation modification (group 4, n=56). Post hoc Tukey Honest significant difference test was used for individual comparisons of radiation exposure/screw and fluoroscopic time/screw. ResultsThe average radiation exposure/screw was 71.45±45.75 μSv/screw for group 1, 18.77±11.51 μSv/screw for group 2, 19.58±7.00 μSv/screw for group 3, and 4.26±2.89 μSv/screw for group 4. By changing imaging manner from continuous multiple shot to intermittent single shot, 73.7% radiation reduction was achieved in the no radiation modification groups (groups 1, 2), and 78.2% radiation reduction was achieved in the radiation modification groups (groups 3, 4). Radiation source modification from continuous mode with standard dose to pulse mode with reduced dose resulted in 72.6% radiation reduction in continuous imaging groups (groups 1, 3) and 77.3% radiation reduction in intermittent imaging groups (groups 2, 4). The average radiation exposure/screw was reduced 94.1% by changing imaging manner and modifying radiation source from continuous imaging with standard fluoroscopy setting (group 1) to intermittent imaging with modified fluoroscopy setting (group 4). A total of 680 screws were reviewed postoperatively, and 99.3% (675) were evaluated as pedicle breach grade 0 (<2 mm). ConclusionThe average radiation exposure/screw for a spinal surgeon can be reduced 94.1% by changing imaging manner and modifying radiation source from real-time imaging with standard dose to intermittent imaging with modified dose. These modifications can be instantly applied to any procedure using fluoroscopic guidance and may reduce the overall radiation exposure of spine surgeons.     

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.     

3D-Slicer联合sina软件辅助椎弓根置钉在椎管内肿瘤手术中的应用

目的 探讨3D-Slicer联合sina软件辅助椎弓根置钉技术在椎管内肿瘤手术中的应用效果。方法 回顾性分析2018年1月至2021年1月手术治疗的46例椎管内肿瘤的临床资料。术中应用3D-Slicer联合sina软件辅助定位置钉26例（观察组）,徒手定位置钉20例（对照组）。术后行C臂、CT扫描,按照Gertzbein-Robbins方法评估置钉的准确性。结果 观察组术中射线量、单钉置入时间、术中出血量、术后术区引流量、术后住院时间均明显低于对照组（P<0.05）。观察组置钉穿破皮质骨发生率（16.38%）、不良置钉率（5.17%）、术中调整置钉率（18.10%）明显低于对照组（分别31.11%、13.33%、37.78%;P<0.05）。两组血管神经损伤及术后1年内钉棒相关并发症发生率均无统计学差异（P>0.05）。结论 与徒手定位置钉相比,3D-Slicer联合sina软件辅助椎弓根置钉,明显提高置钉的准确性,并具减少手术相关的副损伤,缩短住院时间。     

Atornillado anterior de la odontoides empleando tomografía computarizada de haz cónico intraoperatorio y navegación

ObjectiveThe purpose of this study was to asses the value of intraoperative cone-beam CT (O-arm) and stereotactic navigation for the insertion of anterior odontoid screws.Materials and methodsthis was a retrospective review of patients receiving surgical treatment for traumatic odontoid fractures during a period of 18 months.Procedures were guided with O-arm assistance in all cases. The screw position was verified with an intraoperative CT scan. Intraoperative and clinical parameters were evaluated. Odontoid fracture fusion was assessed on postoperative CT scans obtained at 3 and 6 months’ follow-upResultsFive patients were included in this series; 4 patients (80%) were male. Mean age was 63.6 years (range 35-83 years). All fractures were acute type ii odontoid fractures. The mean operative time was 116 minutes (range 60-160 minutes). Successful screw placement, judged by intraoperative computed tomography, was attained in all 5 patients (100%). The average preoperative and postoperative times were 8.6 (range 2-22 days) and 4.2 days (range 3-7 days) respectively. No neurological deterioration occurred after surgery. The rate of bone fusion was 80% (4/5).ConclusionAlthough this initial study evaluated a small number of patients, anterior odontoid screw fixation utilizing the O-arm appears to be safe and accurate. This system allows immediate CT imaging in the operating room to verify screw position.     

Clinical and radiological Comparison of treatment of atlantoaxial instability by posterior C1–C2 transarticular screw fixation or C1 lateral mass-C2 pedicle screw fixation

We compared the clinical and radiological results of posterior atlantoaxial fixation surgery using transarticular screws to those using a polyaxial screw–rod system in 55 patients with symptomatic atlantoaxial instability. Patients underwent posterior C1–C2 fixation: 28 patients (group 1) underwent C1–C2 transarticular screw fixation and 27 patients (group 2) underwent C1 lateral mass–C2 pedicle screw fixation. Patients were followed-up for at least 24 months. The clinical and radiological results were evaluated in the early postoperative period and at 3, 6, 12 and 24 months after surgery. Long-term postoperative stability and bone fusion were examined. After surgery, 93% of patients in group 1 and 96% of patients in group 2 were free of neck pain. The solid fusion rates were 82% for group 1 patients and 96% for group 2 patients at 12 months (p < 0.092). In group 1, three patients showed fibrous union. Four patients had hardware failure due to a screw malposition (one in group 1) and pseudoarthrodesis (two in group 1 and one in group 2). One patient in group 1 had cerebrospinal fluid leakage. One patient in group 2 had occipital neuralgia. One vertebral artery injury occurred during the screw placement in group 1 and another in group 2 during the muscle dissection. C1–C2 transarticular screw fixation and C1 lateral mass–C2 pedicle screw fixation both produced excellent results for stabilization of the atlantoaxial complex, but the radiological outcome tended to be superior in C1 lateral mass–C2 pedicle screw fixation.