Computer-assisted pedicle screw placement for thoracolumbar spine fracture with separate spinal reference clamp placement and registration

BACKGROUND: The objective of the study was to improve the accuracy of computer-assisted pedicle screw installation in the spine. This study evaluates the accuracy of computer-assisted pedicle screw placement with separate spinal reference clamp placement and registration on each instrumented vertebra for thoracolumbar spine fractures. METHODS: Postoperative radiographs and CT scans assessed the accuracy of pedicle screw placement in 21 adult patients on each instrumented vertebra. Screw placements were graded as good if the screws were placed in the central core of the pedicle and the cancellous portion of the body. Screw placements were graded as fair if the screws were placed slightly eccentrically, causing erosion of the pedicular cortex, and with less than a 2-mm perforation of the pedicular cortex. Screw placements were graded as poor if screws were placed eccentrically with a large portion of the screw extending outside the cortical margin of the pedicle and with more than a 2-mm perforation of the pedicular cortex. RESULTS: A total of 140 image-guided pedicle screws were placed in 21 patients: 78 in the thoracic and 62 in the lumbar spine. Of the 140 pedicle screw placements, 96.4% (135/140) were categorized as good; 3.6% (5/140), fair; and 0% were poor. All 5 fair placement screws were placed in the thoracic spine without any mobility. CONCLUSION: Separate registration increases accuracy of screw placement in thoracolumbar pedicle instrumentation. Separate spinal reference clamp placement in the instrumented vertebra provides real-time virtual imaging that decreases the possibility of downward displacement during manual installation of the screw.     

Accuracy of fluoroscopic navigation of pedicle screws. CT-based evaluation of bone screw placement

While the advantages of C-arm navigation in computer-assisted spine surgery are obvious, the accuracy of pedicle screw placement with virtual fluoroscopy still needs to be verified. The C-arm-based ION system (Medtronic Sofamor Danek) was used to navigate pedicle screw insertion in patients undergoing spinal surgery for various conditions. In a prospective study, a total of 160 screws were inserted in the first 30 consecutive patients since introduction of the system at our institution: 54 at the thoracic spine (highest level: TH4) and 106 at the lumbar spine. Computed tomography (CT) scans were performed postoperatively by two independent radiologists to control the accuracy of screw placement at the level of the pedicles after reconstruction of axial images according to Laine et al. The comparison of the calculated accuracy rate of pedicle screw placement using virtual fluoroscopy with reported results achieved with CT-based navigation shows similar results for virtual fluoroscopy and a remarkable increase of accuracy in comparison to reports on conventional pedicle screw placement.     

Computer-assisted thoracic pedicle screw placement: an in vitro feasibility study

STUDY DESIGN: In this cadaveric study, a computer-assisted image guidance system was tested for accuracy of thoracic pedicle screw placement. OBJECTIVES: Evaluate the system's accuracy for thoracic pedicle screw placement in vitro. SUMMARY OF BACKGROUND DATA: The effective use and reliability of pedicle screw instrumentation in providing short-segment stabilization and correction of deformity is well known in the lumbar spine. Pedicle screw placement in the thoracic spine is difficult because of the small dimensions of the thoracic pedicles and risk to the adjacent spinal cord and neurovascular structures. Investigators have shown the improved accuracy of computer-assisted lumbar pedicle screw placement; but the accuracy of computer-assisted thoracic pedicle screw placement, which is becoming more widely used, has not been shown. METHODS: In five human cadavers, 120 thoracic pedicle screws were placed with computer-assisted image guidance. The largest clinically feasible screw was used based on the cross-sectional dimensions of each pedicle. The accuracy was assessed by postoperative computed tomography and visual inspection. RESULTS: The overall pedicle cortex violation was 23 of 120 pedicles (19.2%). Nine violations (7.5%) were graded as major and 14 (11.7%) as minor. A marked and progressive learning curve was evident with the perforation rates that decreased from 37.5% in the first cadaver to 4.2% in the last two cadavers. CONCLUSIONS: Accurate thoracic pedicle screw placement is feasible with computer-assisted surgery. However, as with any other new surgical technology, the learning curve must be recognized and incorporated into the necessary fundamental knowledge and experience for these procedures.     

Stepwise methodology for plain radiographic assessment of pedicle screw placement: a comparison with computed tomography

OBJECTIVE: The objective of this study is to evaluate the effectiveness of a specific methodology for plain radiographic assessment of lumbar pedicle screw position. PURPOSE: To evaluate the effectiveness of using orthogonal plain radiographs and a systematic method of interpretation, developed by the senior author, in assessing the placement of lumbar and lumbosacral pedicle screws. STUDY DESIGN: This was an adult cadaver study of the accuracy of using plain radiographs or computed tomography to assess pedicle screw position. Plain radiographs were performed and compared with computed tomography (CT) scans. Gross anatomic dissections were performed to directly confirm screw position. Variables, including screw material, radiographic view, and screw dimensions, were assessed for their effect on the ability of physicians to determine pedicle screw position. Multiple readers were included in the study, including 1 spine Fellow, 3 experienced orthopedic spine surgeons, and 1 neuroradiologist. METHODS: Five adult cadaveric spines were instrumented with titanium pedicle screws from L1 to S1. Screws were placed outside the confines of the pedicle in all 4 quadrants or within the pedicle using a Latin-Square design. Each cadaver was imaged with orthogonal radiographs and high-resolution CT scans. The spines were then reimaged after the instrumentation was replaced with stainless steel screws placed in the identical position. Finally, each spine was dissected to assess the exact position of the screws. Images were read in a blinded fashion by 1 spine fellow, 2 staff surgeons, and a staff radiologist. The results were compared with the known screw positions at dissection. RESULTS: In total, 120 pedicle screws were placed, 44 (38%) outside the confines of the pedicle. Sensitivity, defined as the percent of the misplaced screws that were correctly identified, was similar across the 3 diagnostic tests, but markedly improved when all CT formats were considered together. Similarly, specificity, defined as the percent of screws correctly read as being placed within the pedicle, was independent of radiographic examination. Sensitivity of the radiographic technique was 70.1% and specificity was 83.0%, whereas sensitivity for CT scans was 84.7% and specificity was 89.7%.There was an observed association with anatomic level, with a consistently less accuracy in detecting screw position at L1 with plain x-ray (P=0.001). Additionally, correct position of stainless steel screws was more difficult to detect as compared with titanium (P=0.033) using either x-rays or CT. Other variables examined, such as screw length and screw diameter, did not have an effect on the ability to read the positioning. CONCLUSIONS: CT scans, often considered the "gold standard" for clinical assessment of pedicle screw placement, have limitations when validated with gross anatomical dissection. The described systematic method for evaluating pedicle screw placement using orthogonal plain radiographs attained accuracy comparable to high-resolution CT scans.     

Computer tomography assessment of pedicle screw placement in thoracic spine: comparison between free hand and a generic 3D-based navigation techniques

Introduction

Although pedicle screw fixation is a well-established technique for the lumbar spine, screw placement in the thoracic spine is more challenging because of the smaller pedicle size and more complex 3D anatomy. The intraoperative use of image guidance devices may allow surgeons a safer, more accurate method for placing thoracic pedicle screws while limiting radiation exposure. This generic 3D imaging technique is a new generation intraoperative CT imaging system designed without compromise to address the needs of a modern OR.

Aim

The aim of our study was to check the accuracy of this generic 3D navigated pedicle screw implants in comparison to free hand technique described by Roy-Camille at the thoracic spine using CT scans.

Material and methods

The material of this study was divided into two groups: free hand group (group I) (18 patients; 108 screws) and 3D group (27 patients; 100 screws). The patients were operated upon from January 2009 to March 2010. Screw implantation was performed during internal fixation for fractures, tumors, and spondylodiscitis of the thoracic spine as well as for degenerative lumbar scoliosis.

Results

The accuracy rate in our work was 89.8 % in the free hand group compared to 98 % in the generic 3D navigated group.

Conclusion

In conclusion, 3D navigation-assisted pedicle screw placement is superior to free hand technique in the thoracic spine.     

The placement of lumbar pedicle screws using computerised stereotactic guidance.

Computer-assisted frameless stereotactic image guidance allows precise preoperative planning and intraoperative localisation of the image. It has been developed and tested in the laboratory. We evaluated the efficacy, clinical results and complications of placement of a pedicle screw in the lumbar spine using this technique. A total of 62 patients (28 men, 34 women) had lumbar decompression and spinal fusion with segmental pedicle screws. Postoperative CT scans were taken of 35 patients to investigate the placement of 330 screws. None showed penetration of the medial or inferior wall of a pedicle. Registration was carried out 66 times. The number of fiducial points used on each registration averaged 5.8 (4 to 7) The mean registration error was 0.75 mm (0.32 to 1.72). This technique provides a safe and reliable guide for placement of transpedicular screws in the lumbar spine.     

导航辅助脊柱胸腰段椎弓根钉植入的临床应用

目的探讨临床运用计算机影像导航技术引导脊柱胸腰段椎弓根钉植入的准确性。方法2003年5月-2007年5月，29例患者接受116枚计算机影像导航技术引导脊柱胸腰段椎弓根钉植入手术治疗，T10-T1250枚胸椎弓根钉，L1-L3 66枚腰椎弓根钉。术中记录椎弓根钉植入所需时间及C-臂透视工作次数，椎弓根钉植入完成后，即行C-臂正侧位摄片并与导航路径进行比较测量。术后CT进行椎弓根层面扫描，根据椎弓根钉与椎弓根皮质问关系分为四级：A=在椎弓根内；B=突破皮质，〈2mm；C=突破皮质，2-4mm；C=突破皮质，〉4mm。结果术后CT椎弓根位置扫描显示：A级101枚（87．07％）；B级10枚（8．62％）；C级2枚（1．72％）；D级3枚（2．59％）。1枚椎弓根钉植入平均所需时间：2．73±0．64min（1．15～4．02min）。下胸椎9枚（7．75％）胸椎弓根钉突破皮质，上腰椎6枚（5．17％）腰椎弓根钉突破皮质，且临床观察未发现与椎弓根钉突破皮质相关的神经血管等并发症。植入的椎弓根钉C-臂正侧位摄片与导航路径吻合比较，进钉点均差2．6mm（最大3．1mm），角度均差3．3°（最大5．4°）。结论计算机影像导航辅助脊柱胸腰段椎弓根钉植入，提供二维、多平面实时显示，保证了脊柱胸腰段椎弓根钉植入的准确性及安全性，明显减少放射线的暴露强度。     

电磁影像导航技术在胸腰椎手术中的应用

目的：探讨电磁影像导航技术在胸腰椎手术中的应用价值。方法：对诊断为腰椎滑脱、腰椎管狭窄症、退行性腰椎侧凸的32例患者(男14例，女18例，平均年龄4l岁)在手术中应用电磁影像导航技术辅助进行椎弓根螺钉置入，10例同时行椎间融合器置入。术后均进行置入螺钉节段的X光平片及CT扫描以确定螺钉置入情况。结果：全组患者安全完成手术，手术时间平均2．8h(1．6～3．7h)，术后影像学检查结果显示所有螺钉置入位置准确。术中与术后无与螺钉置人相关的并发症发生。结论：应用电磁影像导航技术，可以辅助螺钉的准确置入，减少手术时间及放射线照射，尤其对脊柱畸形、严重退变病例或再次手术者，具有显著的优越性。     

Effective in vivo radiation dose with image reconstruction controlled pedicle instrumentation vs. CT-based navigation

There is a rapid increase of computer-assisted surgery (CAS) in the spine for insertion of pedicle screws. In contrast to the traditional technique using fluoroscopy, CT is the primary source for surgical navigation systems. PURPOSE OF THE STUDY: To compare organ and effective doses of fluoroscopy-controlled versus computer-assisted pedicle screw insertion under the aspect of risk reduction and number needed to treat. MATERIALS AND METHODS: In 20 consecutive cases of traditional pedicle screw instrumentation under fluoroscopic control the effective doses were recorded in vivo and the organ doses then calculated. Simulating a spiral CT necessary for the 3-D-model for navigation we defined a spiral CT protocol for the instrumented levels and calculated organ and effective doses from Monte Carlo Results from CT examinations. RESULTS: Organ doses were clearly higher for the CT model than in any of the fluoroscopic procedures in vivo. The mean effective dose for the CT model was fifteen times higher than the fluoroscopic dose: 7.27 mSv versus 0.48 mSv. CONCLUSIONS: In experienced hands open pedicle screw insertion in the thoracic and lumbar spine using fluoroscopy-control requires a fifteen times lower radiation dose than do CT scans necessary for computer-assisted surgery. Regarding the published small percentage of neurological complications in traditional screw insertion technique the use of computer-assisted surgery in pedicle screw insertion using CT scan should be limited to carefully chosen indications. The development of navigation systems based on other data sources than CT should be encouraged.     

IsoC-3D实时定位导航系统引导植入腰椎椎弓根螺钉34例

目的:探讨IsoC-3D实时定位导航系统在腰椎椎弓根螺钉植入手术过程中的应用.方法:对腰椎滑脱、腰椎失稳、脊柱侧弯、腰椎骨折共34例在IsoC-3D实时定位导航系统引导下完成椎弓根螺钉的植入,共植入椎弓根螺钉132枚,术后进行X线平片及CT扫描掌握螺钉的方向和位置.结果:132枚椎弓根螺钉均未穿破椎弓根,椎弓根螺钉的方向、深度、位置均相当理想,全部病例无硬膜、神经根损伤.结论:IsoC-3D实时定位导航系统可以准确引导腰椎椎弓根螺钉的植入,避免椎弓根螺钉植入相关的并发症.     

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.     

Computer-assisted orthopedic surgery with individual templates and comparison to conventional operation method

STUDY DESIGN: Comparison was made of the accuracy of a pedicle bore performed by conventional technique and by using an individual template in the lumbar spine of cadavers. OBJECTIVES: The fixation of pedicle screws necessitates a high amount of surgical skill and experience to avoid lesions of nerves and vessels. By using individual templates in a cadaver study the goal was to prove the accuracy and efficiency of this less-invasive image-guided surgery in comparison with the conventional technique by fluoroscopy and computed tomographic (CT) scan. SUMMARY OF BACKGROUND DATA: Based on three-dimensional models generated from CT scans of the lumbar spine, precise preoperative planning of the position and trajectory of pedicle screws is possible. In comparison with other means of computer-assisted spine surgery with navigation systems, in which a time-consuming intraoperative matching of the bone surface structure is necessary, the use of individual templates enables the surgeon to reduce the operation time considerably. METHODS: Individual templates are customized on the basis of three-dimensional reconstructions of the bone structures extracted from CT image data and depending on the individual preoperative surgical planning, which uses the desktop image processing system for orthopedic surgery (DISOS). A desktop-computer-controlled milling device is used as a three-dimensional printer to automatically mold the shape of small reference areas of the bone surface into the body of the template. Postoperative CT scans were obtained and the accuracy of the pedicle bore rated by two independent observers. RESULTS: The preparation time with the individual template lasted slightly longer than with the conventional operation technique (555 seconds and 482 seconds, respectively). Fluoroscopic study took a mean time of 31.5 seconds, with the conventional operation technique and 5.5 seconds with the individual template. The assessment of the postoperative CT scans demonstrated a higher accuracy of the pedicle bore with the individual template. CONCLUSIONS: This cadaveric study has shown that overall operation time including the fluoroscopy time can be shortened by using the individual template for the pedicle bore. The individual template is an alternative to the computer-assisted navigation systems with a good cost-performance ratio without excessive technical workload on the physicians or the surgical personnel. Further investigations must be conducted to validate the clinical applicability of this system.     

Comparison of Radiation Exposure in Lumbar Pedicle Screw Placement With Fluoroscopy Vs Computer-Assisted Image Guidance With Intraoperative Three-Dimensional Imaging

Background/objective: Little is known about the long-term effects of chronic exposure to ionizingradiation. Studies have shown that spine surgeons may be exposed to significantly more radiation than thatobserved in surgery on the appendicular skeleton. Computer-assisted image guidance systems have beenshown in preliminary studies to enable accurate instrumentation of the spine. Computer-assisted image guidance systems may havesignificant application to the surgical management of spinal trauma and deformity. The objective of this study was to compare C-arm fluoroscopy and computer-assisted imageguidance in terms of radiation exposure to the operative surgeon when placing pedicle screw-rod constructsin cadaver specimens.

Methods: Twelve single-level (2 contiguous vertebral bodies) lumbar pedicle screw-rod constructs (48screws) in 4 fresh cadavers were placed using standard C-arm fluoroscopy and computer-assisted imageguidance (Stealth Station with lso-C^3D ).Pedicle screw-rod constructs were placed at L1-L2, L3-L4, and L5-S1 in 4 fresh cadaver specimens. Imaging was alternated between C-arm fluoroscopy and computer-assistedimage guidance with Stealth Station lso-C^3D. Radiation exposure was measured using ringand badge dosimeters to monitor the thyroid, torso, and index finger. Postprocedure CT scans were obtained to judge accuracy of screw placement.

Results: Mean radiation exposure to the torso was 4.33 ± 2.66 mRemfor procedures performed with standard fluoroscopy and 0.33 ± 0.82 mRem for procedures performed with computer-assisted image guidance. This difference was statistically significant (P = 0.012). Radiation exposure to the index finger and thyroid was negligible for all procedures. The accuracy of screw placement was similar for both techniques.

Conclusions: Computer-assisted image guidance systems allow for the safe and accurate placement ofpedicle screw-rod constructs with a significant reduction in exposure to ionizing radiation to the torso of theoperating surgeon.     

Lumbar pedicle screw placement: Using only AP plane imaging

Background:

Variations in the pedicle morphology and presence of spinal deformities can make pedicle screw placement challenging. Recently, computerized tomography (CT) guided screw placement has reportedly improved the surgical accuracy of pedicle screw insertion. However, it is time consuming and expensive. We combined single-plane fluoroscopy in AP projection alone with tactile guidance for placing pedicle screws more efficiently and accurately. This report presents our results with this technique.

Materials and Methods:

An Institutional Review Board (IRB) approved retrospective study was carried out on 308 patients who underwent lumbar spinal fusion with 1806 pedicle screws placed using fluoroscopy only in the AP plane. There were 182 patients with two-level fusion, 79 with single-level fusion, 26 with three-level fusion, and 21 with more than three-level fusions. The indications of surgery included spondylolisthesis, adult scoliosis, revision surgery, lumbar canal stenosis, and discogenic pain. Pedicle screws were inserted under fluoroscopic guidance in the AP plane alone with a final lateral image after completion of implant placement. Radiographs were performed postoperatively in all patients and CT scans were obtained on 78 patients with 588 screws.

Results:

Twenty nine (5%) cortical wall perforations were noted amongst the 588 screws that were evaluated with a CT scan and did not result in postoperative vascular or neural complications. Anterior cortical vertebral violation was noted in 14 patients, while in 9 patients the screws penetrated the lateral wall of the pedicle. The medial wall of the pedicle was encroached in six patients with no frank perforations.

Conclusion:

Placement of pedicle screws under fluoroscopic guidance using AP plane imaging alone with tactile guidance is safe, fast, and reliable. However, a good understanding of the radiographic landmarks is a prerequisite.     

Rapid prototyping drill guide template for lumbar pedicle screw placement

To develop a novel method of spinal pedical stereotaxy by reverse engineering and rapid prototyping techniques, and to validate its accuracy by experimental and clinical studies. Methods: A 3D reconstruction model for the desired lumbar vertebra was generated by using the Mimics 10.11 software, and the optimal screw size and orientation were determined using the reverse engineering software. Afterwards, a drill template was created by reverse engi-neering principle, whose surface was the antitemplate of the vertebral surface. The drill template and its correspond-ing vertebra were manufactured using the rapid prototyping technique. Results: The accuracy of the drill template was con-firmed by drilling screw trajectory into the vertebral biomodel preoperatively. This method also showed its ability to cus-tomize the placement and size of each screw based on the unique morphology of the lumbar vertebra.The drill tem-plate fits the postural surface of the vertebra very well in the cadaver experiment. Postoperative CT scans for controlling the pedicle bore showed that the personalized template had a high precision in cadaver experiment and clinical application. No misplacement occurred by using the per-sonalized template. During surgery, no additional computer assistance was needed.Conclusions: The authors have developed a novel drill template for lumbar pedicle screw placement with good applicability and high accuracy. The potential use of drill templates to place lumbar pedicle screws is promising. Our methodology appears to provide an accurate technique and trajectory for pedicle screw placement in the lumbar spine.     

Rapid prototyping drill guide template for lumbar pedicle screw placement

To develop a novel method of spinal pedical stereotaxy by reverse engineering and rapid prototyping techniques, and to validate its accuracy by experimental and clinical studies. Methods: A 3D reconstruction model for the desired lumbar vertebra was generated by using the Mimics 10.11 software, and the optimal screw size and orientation were determined using the reverse engineering software. Afterwards, a drill template was created by reverse engi-neering principle, whose surface was the antitemplate of the vertebral surface. The drill template and its correspond-ing vertebra were manufactured using the rapid prototyping technique. Results: The accuracy of the drill template was con-firmed by drilling screw trajectory into the vertebral biomodel preoperatively. This method also showed its ability to cus-tomize the placement and size of each screw based on the unique morphology of the lumbar vertebra.The drill tem-plate fits the postural surface of the vertebra very well in the cadaver experiment. Postoperative CT scans for controlling the pedicle bore showed that the personalized template had a high precision in cadaver experiment and clinical application. No misplacement occurred by using the per-sonalized template. During surgery, no additional computer assistance was needed.Conclusions: The authors have developed a novel drill template for lumbar pedicle screw placement with good applicability and high accuracy. The potential use of drill templates to place lumbar pedicle screws is promising. Our methodology appears to provide an accurate technique and trajectory for pedicle screw placement in the lumbar spine.     

快速成型模型佐助胸腰椎椎弓根置钉的研究

目的 探讨快速成型技术佐助胸腰椎椎弓根螺钉置入的准确性和可靠性.方法 将患者分成两组,快速成型组26例,传统手法置钉组26例,由同一位医师分别采用快速成型模型佐助置钉法和传统手法置钉进行胸腰椎椎弓根螺钉置入.术后CT扫描比较两种方法的置钉准确性.结果 快速成型模型佐助置钉156枚,其中3枚穿破皮质,成功率98.08％,绝对风险率0.64％;传统手法置钉121枚,11枚穿破皮质,成功率90.91％,绝对风险率4.13％.两组病例均未出现神经血管损伤并发症,快速成型佐助置钉法准确率明显高于传统手法置钉,安全性提高,差异具有统计学意义(P＜0.05).结论 快速成型模型佐助胸腰椎椎弓根置钉,可提高准确率和安全性,操作简单,符合个体化置钉,为胸腰椎椎弓根螺钉置入提供一种新方法.     

O-arm计算机导航辅助脊柱椎弓根螺钉置入的准确性

[目的]分析O-arm计算机辅助导航技术在脊柱椎弓根螺钉置入的准确性。[方法]回顾性分析2017年1月~2018年9月本院椎弓根螺钉置入患者575例,根据椎弓根螺钉置入方式不同,分为两组。导航组采用O-arm计算机辅助导航技术系统置入椎弓根螺钉233例,传统组采用传统徒手法置入椎弓根螺钉342例。行CT检查,依据Neo分型评估置钉准确性。[结果]导航组共置入1459枚椎弓根螺钉,其中C1~7置入222枚,T1~12置入535枚,L1~5置入652枚,S1置入50枚。每名患者置钉数量1~24枚,平均(6.26±3.77)枚。传统组共置入1724枚椎弓根螺钉,其中C1~7置入269枚,T1~12置入601枚,L1~5置入785枚,S1置入87枚。每名患者置钉数量1~20枚,平均(5.67±4.11)枚。导航组全部病例顺利完成手术,术中无血管、神经损伤等并发症,置钉安全率为100%,传统组有4例发生血管、神经损伤等并发症。所有患者术后进行12~24个月随访,随访过程均未发生不良事件。依据CT影像Neo分级标准,导航0型及1型椎弓根螺钉的成功置入率达98.01%,而传统组0型及1型椎弓根螺钉的成功置入率91.85%;两组间置入螺钉准确性的差异具有统计学意义(P<0.05)。[结论]与传统C臂X线机等徒手置钉方式相比,O-arm计算机辅助导航技术可提高脊柱椎弓根螺钉置入准确性,同时降低神经、血管等并发症的发生。     

Rapid prototyping drill guide template for lumbar pedicle screw placement

To develop a novel method of spinal pedical stereotaxy by reverse engineering and rapid prototyping techniques, and to validate its accuracy by experimental and clinical studies. Methods: A 3D reconstruction model for the desired lumbar vertebra was generated by using the Mimics 10.11 software, and the optimal screw size and orientation were determined using the reverse engineering software. Afterwards, a drill template was created by reverse engi-neering principle, whose surface was the antitemplate of the vertebral surface. The drill template and its correspond-ing vertebra were manufactured using the rapid prototyping technique. Results: The accuracy of the drill template was con-firmed by drilling screw trajectory into the vertebral biomodel preoperatively. This method also showed its ability to cus-tomize the placement and size of each screw based on the unique morphology of the lumbar vertebra.The drill tem-plate fits the postural surface of the vertebra very well in the cadaver experiment. Postoperative CT scans for controlling the pedicle bore showed that the personalized template had a high precision in cadaver experiment and clinical application. No misplacement occurred by using the per-sonalized template. During surgery, no additional computer assistance was needed.Conclusions: The authors have developed a novel drill template for lumbar pedicle screw placement with good applicability and high accuracy. The potential use of drill templates to place lumbar pedicle screws is promising. Our methodology appears to provide an accurate technique and trajectory for pedicle screw placement in the lumbar spine.     

Rapid prototyping drill guide template for lumbar pedicle screw placement

To develop a novel method of spinal pedical stereotaxy by reverse engineering and rapid prototyping techniques, and to validate its accuracy by experimental and clinical studies. Methods: A 3D reconstruction model for the desired lumbar vertebra was generated by using the Mimics 10.11 software, and the optimal screw size and orientation were determined using the reverse engineering software. Afterwards, a drill template was created by reverse engi-neering principle, whose surface was the antitemplate of the vertebral surface. The drill template and its correspond-ing vertebra were manufactured using the rapid prototyping technique. Results: The accuracy of the drill template was con-firmed by drilling screw trajectory into the vertebral biomodel preoperatively. This method also showed its ability to cus-tomize the placement and size of each screw based on the unique morphology of the lumbar vertebra.The drill tem-plate fits the postural surface of the vertebra very well in the cadaver experiment. Postoperative CT scans for controlling the pedicle bore showed that the personalized template had a high precision in cadaver experiment and clinical application. No misplacement occurred by using the per-sonalized template. During surgery, no additional computer assistance was needed.Conclusions: The authors have developed a novel drill template for lumbar pedicle screw placement with good applicability and high accuracy. The potential use of drill templates to place lumbar pedicle screws is promising. Our methodology appears to provide an accurate technique and trajectory for pedicle screw placement in the lumbar spine.