scholarly journals Feasibility and Accuracy of Thoracolumbar Pedicle Screw Placement Using an Augmented Reality Head Mounted Device

Sensors ◽  
2022 ◽  
Vol 22 (2) ◽  
pp. 522
Author(s):  
Henrik Frisk ◽  
Eliza Lindqvist ◽  
Oscar Persson ◽  
Juliane Weinzierl ◽  
Linda K. Bruetzel ◽  
...  
Keyword(s):  
Augmented Reality ◽  
Navigation System ◽  
Pedicle Screws ◽  
Screw Placement ◽  
Mean Deviation ◽  
Angular Deviation ◽  
Clinical Accuracy ◽  
Screw Position ◽  
Grading Scale ◽  
The Mean

Background: To investigate the accuracy of augmented reality (AR) navigation using the Magic Leap head mounted device (HMD), pedicle screws were minimally invasively placed in four spine phantoms. Methods: AR navigation provided by a combination of a conventional navigation system integrated with the Magic Leap head mounted device (AR-HMD) was used. Forty-eight screws were planned and inserted into Th11-L4 of the phantoms using the AR-HMD and navigated instruments. Postprocedural CT scans were used to grade the technical (deviation from the plan) and clinical (Gertzbein grade) accuracy of the screws. The time for each screw placement was recorded. Results: The mean deviation between navigation plan and screw position was 1.9 ± 0.7 mm (1.9 [0.3–4.1] mm) at the entry point and 1.4 ± 0.8 mm (1.2 [0.1–3.9] mm) at the screw tip. The angular deviation was 3.0 ± 1.4° (2.7 [0.4–6.2]°) and the mean time for screw placement was 130 ± 55 s (108 [58–437] s). The clinical accuracy was 94% according to the Gertzbein grading scale. Conclusion: The combination of an AR-HMD with a conventional navigation system for accurate minimally invasive screw placement is feasible and can exploit the benefits of AR in the perspective of the surgeon with the reliability of a conventional navigation system.

scholarly journals First in-human report of the clinical accuracy of thoracolumbar percutaneous pedicle screw placement using augmented reality guidance

2021 ◽  
Vol 51 (2) ◽  
pp. E10
Author(s):  
Alexander T. Yahanda ◽  
Emelia Moore ◽  
Wilson Z. Ray ◽  
Brenton Pennicooke ◽  
Jack W. Jennings ◽  
...  
Keyword(s):  
Augmented Reality ◽  
Lower Extremity ◽  
Pedicle Screw ◽  
Pedicle Screws ◽  
Screw Placement ◽  
Spinal Tumors ◽  
Pedicle Screw Placement ◽  
Percutaneous Pedicle Screw ◽  
Clinical Accuracy ◽  
The Mean

OBJECTIVE Augmented reality (AR) is an emerging technology that has great potential for guiding the safe and accurate placement of spinal hardware, including percutaneous pedicle screws. The goal of this study was to assess the accuracy of 63 percutaneous pedicle screws placed at a single institution using an AR head-mounted display (ARHMD) system. METHODS Retrospective analyses were performed for 9 patients who underwent thoracic and/or lumbar percutaneous pedicle screw placement guided by ARHMD technology. Clinical accuracy was assessed via the Gertzbein-Robbins scale by the authors and by an independent musculoskeletal radiologist. Thoracic pedicle subanalysis was also performed to assess screw accuracy based on pedicle morphology. RESULTS Nine patients received thoracic or lumbar AR-guided percutaneous pedicle screws. The mean age at the time of surgery was 71.9 ± 11.5 years and the mean number of screws per patient was 7. Indications for surgery were spinal tumors (n = 4, 44.4%), degenerative disease (n = 3, 33.3%), spinal deformity (n = 1, 11.1%), and a combination of deformity and infection (n = 1, 11.1%). Presenting symptoms were most commonly low-back pain (n = 7, 77.8%) and lower-extremity weakness (n = 5, 55.6%), followed by radicular lower-extremity pain, loss of lower-extremity sensation, or incontinence/urinary retention (n = 3 each, 33.3%). In all, 63 screws were placed (32 thoracic, 31 lumbar). The accuracy for these screws was 100% overall; all screws were Gertzbein-Robbins grade A or B (96.8% grade A, 3.2% grade B). This accuracy was achieved in the thoracic spine regardless of pedicle cancellous bone morphology. CONCLUSIONS AR-guided surgery demonstrated a 100% accuracy rate for the insertion of 63 percutaneous pedicle screws in 9 patients (100% rate of Gertzbein-Robbins grade A or B screw placement). Using an ARHMS system for the placement of percutaneous pedicle screws showed promise, but further validation using a larger cohort of patients across multiple surgeons and institutions will help to determine the true accuracy enabled by this technology.

scholarly journals Positioning Performance of Power and Manual Drivers in Posterior Spinal Fusion Procedures

2017 ◽  
Vol 2017 ◽  
pp. 1-9
Author(s):  
J. Micah Prendergast ◽  
Alexander C. Perry ◽  
Vikas V. Patel ◽  
Emily M. Lindley ◽  
Mark E. Rentschler
Keyword(s):  
Spinal Fusion ◽  
Navigation System ◽  
Surgical Navigation ◽  
Pedicle Screws ◽  
Posterior Spinal Fusion ◽  
Screw Placement ◽  
Reference Plane ◽  
Mean Deviation ◽  
Angular Deviation ◽  
Spinal Fusion Surgery

This work presents an analysis and comparison of the efficacy of two methods for pedicle screw placement during posterior spinal fusion surgery. A total of 100 screws (64 manual and 36 power driven), all placed utilizing a surgical navigation system, were analyzed and compared. Final screw placement was compared to initial surgical plans using the navigation system, and the final screw locations were analyzed on the basis of angular deviation from these planned trajectories as well as screw translation within a critical reference plane. The power driver was found to insignificantly decrease the resulting angular deviation of these pedicle screws with a mean deviation of 3.35 degrees compared to 3.44 degrees with the manual driver (p=0.853). Conversely, the power driver was found to increase the translational distance in the critical region, with mean deviations of 2.45 mm for the power driver compared to 1.54 mm with the manual driver. The increase in translational deviation was significant (p=0.002) indicating that there may be some loss in performance from the adoption of the power driver.

scholarly journals A cadaveric precision and accuracy analysis of augmented reality–mediated percutaneous pedicle implant insertion

2020 ◽  
pp. 1-9 ◽  
Author(s):  
Camilo A. Molina ◽  
Frank M. Phillips ◽  
Matthew W. Colman ◽  
Wilson Z. Ray ◽  
Majid Khan ◽  
...  
Keyword(s):  
Augmented Reality ◽  
Pedicle Screw ◽  
Pedicle Screws ◽  
Angular Deviation ◽  
Screw Insertion ◽  
Head Mounted Display ◽  
Percutaneous Pedicle Screw ◽  
Field Of Vision ◽  
Clinical Accuracy ◽  
Screw Position

OBJECTIVEAugmented reality–mediated spine surgery (ARMSS) is a minimally invasive novel technology that has the potential to increase the efficiency, accuracy, and safety of conventional percutaneous pedicle screw insertion methods. Visual 3D spinal anatomical and 2D navigation images are directly projected onto the operator’s retina and superimposed over the surgical field, eliminating field of vision and attention shift to a remote display. The objective of this cadaveric study was to assess the accuracy and precision of percutaneous ARMSS pedicle implant insertion.METHODSInstrumentation was placed in 5 cadaveric torsos via ARMSS with the xvision augmented reality head-mounted display (AR-HMD) platform at levels ranging from T5 to S1 for a total of 113 total implants (93 pedicle screws and 20 Jamshidi needles). Postprocedural CT scans were graded by two independent neuroradiologists using the Gertzbein-Robbins scale (grades A–E) for clinical accuracy. Technical precision was calculated using superimposition analysis employing the Medical Image Interaction Toolkit to yield angular trajectory (°) and linear screw tip (mm) deviation from the virtual pedicle screw position compared with the actual pedicle screw position on postprocedural CT imaging.RESULTSThe overall implant insertion clinical accuracy achieved was 99.1%. Lumbosacral and thoracic clinical accuracies were 100% and 98.2%, respectively. Specifically, among all implants inserted, 112 were noted to be Gertzbein-Robbins grade A or B (99.12%), with only 1 medial Gertzbein-Robbins grade C breach (> 2-mm pedicle breach) in a thoracic pedicle at T9. Precision analysis of the inserted pedicle screws yielded a mean screw tip linear deviation of 1.98 mm (99% CI 1.74–2.22 mm) and a mean angular error of 1.29° (99% CI 1.11°–1.46°) from the projected trajectory. These data compare favorably with data from existing navigation platforms and regulatory precision requirements mandating that linear and angular deviation be less than 3 mm (p < 0.01) and 3° (p < 0.01), respectively.CONCLUSIONSPercutaneous ARMSS pedicle implant insertion is a technically feasible, accurate, and highly precise method.

scholarly journals Initial Intraoperative Experience with Robotic-Assisted Pedicle Screw Placement with Cirq® Robotic Alignment: An Evaluation of the First 70 Screws

2021 ◽  
Vol 10 (24) ◽  
pp. 5725
Author(s):  
Mirza Pojskić ◽  
Miriam Bopp ◽  
Christopher Nimsky ◽  
Barbara Carl ◽  
Benjamin Saβ
Keyword(s):  
Pedicle Screw ◽  
Intraoperative Imaging ◽  
Pedicle Screws ◽  
Robotic Arm ◽  
Screw Placement ◽  
Angular Deviation ◽  
Pedicle Screw Placement ◽  
Robotic Assisted ◽  
The Mean ◽  
Mean Time

Background: Robot-guided spine surgery is based on a preoperatively planned trajectory that is reproduced in the operating room by the robotic device. This study presents our initial experience with thoracolumbar pedicle screw placement using Brainlab’s Cirq® surgeon-controlled robotic arm (BrainLab, Munich, Germany). Methods: All patients who underwent robotic-assisted implantation of pedicle screws in the thoracolumbar spine were included in the study. Our workflow, consisting of preoperative imagining, screw planning, intraoperative imaging with automatic registration, fusion of the preoperative and intraoperative imaging with a review of the preplanned screw trajectories, robotic-assisted insertion of K-wires, followed by a fluoroscopy-assisted insertion of pedicle screws and control iCT scan, is described. Results: A total of 12 patients (5 male and 7 females, mean age 67.4 years) underwent 13 surgeries using the Cirq® Robotic Alignment Module for thoracolumbar pedicle screw implantation. Spondylodiscitis, metastases, osteoporotic fracture, and spinal canal stenosis were detected. A total of 70 screws were implanted. The mean time per screw was 08:27 ± 06:54 min. The mean time per screw for the first 7 surgeries (first 36 screws) was 16:03 ± 09:32 min and for the latter 6 surgeries (34 screws) the mean time per screw was 04:35 ± 02:11 min (p < 0.05). Mean entry point deviation was 1.9 ± 1.23 mm, mean deviation from the tip of the screw was 2.61 ± 1.6 mm and mean angular deviation was 3.5° ± 2°. For screw-placement accuracy we used the CT-based Gertzbein and Robbins System (GRS). Of the total screws, 65 screws were GRS A screws (92.85%), one screw was a GRS B screw, and two further screws were grade C. Two screws were D screws (2.85%) and underwent intraoperative revision. There were no perioperative deficits. Conclusion: Brainlab’s Cirq® Robotic Alignment surgeon-controlled robotic arm is a safe and beneficial method for accurate thoracolumbar pedicle screw placement with high accuracy.

Clinical Accuracy, Technical Precision, and Workflow of the First in Human Use of an Augmented-Reality Head Mound Display Stereotactic Navigation System for Spine Surgery

2020 ◽  
Author(s):  
Camilo A Molina ◽  
Daniel M Sciubba ◽  
Jacob K Greenberg ◽  
Majid Khan ◽  
Timothy Witham
Keyword(s):  
Augmented Reality ◽  
Spine Surgery ◽  
Pedicle Screws ◽  
Technical Note ◽  
Angular Deviation ◽  
Precision Analysis ◽  
Accuracy And Precision ◽  
Clinical Scenarios ◽  
Clinical Accuracy ◽  
Spine Navigation

Abstract BACKGROUND Augmented reality mediated spine surgery is a novel technology for spine navigation. Benchmark cadaveric data have demonstrated high accuracy and precision leading to recent regulatory approval. Absence of respiratory motion in cadaveric studies may positively bias precision and accuracy results and analogous investigations are prudent in live clinical scenarios. OBJECTIVE To report a technical note, accuracy, precision analysis of the first in-human deployment of this technology. METHODS A 78-yr-old female underwent an L4-S1 decompression, pedicle screw, and rod fixation for degenerative spine disease. Six pedicle screws were inserted via AR-HMD (xvision; Augmedics, Chicago, Illinois) navigation. Intraoperative computed tomography was used for navigation registration as well as implant accuracy and precision assessment. Clinical accuracy was graded per the Gertzbein-Robbins (GS) scale by an independent neuroradiologist. Technical precision was analyzed by comparing 3-dimensional (3D) (x, y, z) virtual implant vs real implant position coordinates and reported as linear (mm) and angular (°) deviation. Present data were compared to benchmark cadaveric data. RESULTS Clinical accuracy (per the GS grading scale) was 100%. Technical precision analysis yielded a mean linear deviation of 2.07 mm (95% CI: 1.62-2.52 mm) and angular deviation of 2.41° (95% CI: 1.57-3.25°). In comparison to prior cadaveric data (99.1%, 2.03 ± 0.99 mm, 1.41 ± 0.61°; GS accuracy 3D linear and angular deviation, respectively), the present results were not significantly different (P &gt; .05). CONCLUSION The first in human deployment of the single Food and Drug Administration approved AR-HMD stereotactic spine navigation platform demonstrated clinical accuracy and technical precision of inserted hardware comparable to previously acquired cadaveric studies.

Clinical accuracy and initial experience with augmented reality–assisted pedicle screw placement: the first 205 screws

2021 ◽  
pp. 1-7
Author(s):  
Ann Liu ◽  
Yike Jin ◽  
Ethan Cottrill ◽  
Majid Khan ◽  
Erick Westbroek ◽  
...  
Keyword(s):  
Augmented Reality ◽  
Pedicle Screw ◽  
Spinal Instrumentation ◽  
Deformity Correction ◽  
Pedicle Screws ◽  
Screw Placement ◽  
Pedicle Screw Placement ◽  
Lower Extremity Weakness ◽  
Head Mounted Display ◽  
Clinical Accuracy

OBJECTIVE Augmented reality (AR) is a novel technology which, when applied to spine surgery, offers the potential for efficient, safe, and accurate placement of spinal instrumentation. The authors report the accuracy of the first 205 pedicle screws consecutively placed at their institution by using AR assistance with a unique head-mounted display (HMD) navigation system. METHODS A retrospective review was performed of the first 28 consecutive patients who underwent AR-assisted pedicle screw placement in the thoracic, lumbar, and/or sacral spine at the authors’ institution. Clinical accuracy for each pedicle screw was graded using the Gertzbein-Robbins scale by an independent neuroradiologist working in a blinded fashion. RESULTS Twenty-eight consecutive patients underwent thoracic, lumbar, or sacral pedicle screw placement with AR assistance. The median age at the time of surgery was 62.5 (IQR 13.8) years and the median body mass index was 31 (IQR 8.6) kg/m2. Indications for surgery included degenerative disease (n = 12, 43%); deformity correction (n = 12, 43%); tumor (n = 3, 11%); and trauma (n = 1, 4%). The majority of patients (n = 26, 93%) presented with low-back pain, 19 (68%) patients presented with radicular leg pain, and 10 (36%) patients had documented lower extremity weakness. A total of 205 screws were consecutively placed, with 112 (55%) placed in the lumbar spine, 67 (33%) in the thoracic spine, and 26 (13%) at S1. Screw placement accuracy was 98.5% for thoracic screws, 97.8% for lumbar/S1 screws, and 98.0% overall. CONCLUSIONS AR depicted through a unique HMD is a novel and clinically accurate technology for the navigated insertion of pedicle screws. The authors describe the first 205 AR-assisted thoracic, lumbar, and sacral pedicle screws consecutively placed at their institution with an accuracy of 98.0% as determined by a Gertzbein-Robbins grade of A or B.

scholarly journals Three-dimensional assessment of robot-assisted pedicle screw placement accuracy and instrumentation reliability based on a preplanned trajectory

2020 ◽  
Vol 33 (4) ◽  
pp. 519-528
Author(s):  
Bowen Jiang ◽  
Zach Pennington ◽  
Alex Zhu ◽  
Stavros Matsoukas ◽  
A. Karim Ahmed ◽  
...  
Keyword(s):  
Pedicle Screw ◽  
Tertiary Care ◽  
Pedicle Screws ◽  
Screw Placement ◽  
Lumbosacral Spine ◽  
Grading System ◽  
Angular Deviation ◽  
Pedicle Screw Placement ◽  
Placement Accuracy ◽  
The Mean

OBJECTIVERobotic spine surgery systems are increasingly used in the US market. As this technology gains traction, however, it is necessary to identify mechanisms that assess its effectiveness and allow for its continued improvement. One such mechanism is the development of a new 3D grading system that can serve as the foundation for error-based learning in robot systems. Herein the authors attempted 1) to define a system of providing accuracy data along all three pedicle screw placement axes, that is, cephalocaudal, mediolateral, and screw long axes; and 2) to use the grading system to evaluate the mean accuracy of thoracolumbar pedicle screws placed using a single commercially available robotic system.METHODSThe authors retrospectively reviewed a prospectively maintained, IRB-approved database of patients at a single tertiary care center who had undergone instrumented fusion of the thoracic or lumbosacral spine using robotic assistance. Patients with preoperatively planned screw trajectories and postoperative CT studies were included in the final analysis. Screw accuracy was measured as the net deviation of the planned trajectory from the actual screw trajectory in the mediolateral, cephalocaudal, and screw long axes.RESULTSThe authors identified 47 patients, 51% male, whose pedicles had been instrumented with a total of 254 screws (63 thoracic, 191 lumbosacral). The patients had a mean age of 61.1 years and a mean BMI of 30.0 kg/m2. The mean screw tip accuracies were 1.3 ± 1.3 mm, 1.2 ± 1.1 mm, and 2.6 ± 2.2 mm in the mediolateral, cephalocaudal, and screw long axes, respectively, for a net linear deviation of 3.6 ± 2.3 mm and net angular deviation of 3.6° ± 2.8°. According to the Gertzbein-Robbins grading system, 184 screws (72%) were classified as grade A and 70 screws (28%) as grade B. Placement of 100% of the screws was clinically acceptable.CONCLUSIONSThe accuracy of the discussed robotic spine system is similar to that described for other surgical systems. Additionally, the authors outline a new method of grading screw placement accuracy that measures deviation in all three relevant axes. This grading system could provide the error signal necessary for unsupervised machine learning by robotic systems, which would in turn support continued improvement in instrumentation placement accuracy.

scholarly journals Comparison of implant placement accuracy in two different preoperative digital workflows: navigated vs. pilot-drill-guided surgery

2021 ◽  
Vol 7 (1) ◽  
Author(s):  
Johannes Spille ◽  
Feilu Jin ◽  
Eleonore Behrens ◽  
Yahya Açil ◽  
Jürgen Lichtenstein ◽  
...  
Keyword(s):  
Navigation System ◽  
Entry Point ◽  
Angular Deviation ◽  
Guided Surgery ◽  
Implant Placement ◽  
Drill Guide ◽  
Navigation Group ◽  
3D Printed ◽  
The Mean ◽  
Master Model

Abstract Background The aim of the study is to evaluate the accuracy of a new implant navigation system on two different digital workflows. Methods A total of 18 phantom jaws consisting of hard and non-warping plastic and resembling edentulous jaws were used to stimulate a clinical circumstance. A conventional pilot-drill guide was conducted by a technician, and a master model was set by using this laboratory-produced guide. After cone beam computed tomography (CBCT) and 3D scanning of the master models, two different digital workflows (marker tray in CBCT and 3D-printed tray) were performed based on the Digital Imaging Communication in Medicine files and standard tessellation language files. Eight Straumann implants (4.1 mm × 10 mm) were placed in each model, six models for each group, resulting in 144 implant placements in total. Postoperative CBCT were taken, and deviations at the entry point and apex as well as angular deviations were measured compared to the master model. Results The mean total deviations at the implant entry point for MTC (marker tray in CBCT), 3dPT (3d-printed tray), and PDG (pilot-drill guide) were 1.024 ± 0.446 mm, 1.027 ± 0.455 mm, and 1.009 ± 0.415 mm, respectively, and the mean total deviations at the implant apex were 1.026 ± 0.383 mm, 1.116 ± 0.530 mm, and 1.068 ± 0.384 mm. The angular deviation for the MTC group was 2.22 ± 1.54°. The 3dPT group revealed an angular deviation of 1.95 ± 1.35°, whereas the PDG group showed a mean angular deviation of 2.67 ± 1.58°. Although there were no significant differences among the three groups (P > 0.05), the navigation groups showed lesser angular deviations compared to the pilot-drill-guide (PDG) group. Implants in the 3D-printed tray navigation group showed higher deviations at both entry point and apex. Conclusions The accuracy of the evaluated navigation system was similar with the accuracy of a pilot-drill guide. Accuracy of both preoperative workflows (marker tray in CBCT or 3D-printed tray) was reliable for clinical use.

scholarly journals A Novel Augmented-Reality-Based Surgical Navigation System for Spine Surgery in a Hybrid Operating Room: Design, Workflow, and Clinical Applications

2019 ◽  
Vol 18 (5) ◽  
pp. 496-502 ◽  
Author(s):  
Erik Edström ◽  
Gustav Burström ◽  
Rami Nachabe ◽  
Paul Gerdhem ◽  
Adrian Elmi Terander
Keyword(s):  
Augmented Reality ◽  
Radiation Exposure ◽  
Pedicle Screw ◽  
Operating Room ◽  
Wound Closure ◽  
Surgical Navigation ◽  
Pedicle Screws ◽  
Screw Placement ◽  
Hybrid Operating Room ◽  
Pedicle Screw Placement

Abstract BACKGROUND Treatment of several spine disorders requires placement of pedicle screws. Detailed 3-dimensional (3D) anatomic information facilitates this process and improves accuracy. OBJECTIVE To present a workflow for a novel augmented-reality-based surgical navigation (ARSN) system installed in a hybrid operating room for anatomy visualization and instrument guidance during pedicle screw placement. METHODS The workflow includes surgical exposure, imaging, automatic creation of a 3D model, and pedicle screw path planning for instrument guidance during surgery as well as the actual screw placement, spinal fixation, and wound closure and intraoperative verification of the treatment results. Special focus was given to process integration and minimization of overhead time. Efforts were made to manage staff radiation exposure avoiding the need for lead aprons. Time was kept throughout the procedure and subdivided to reflect key steps. The navigation workflow was validated in a trial with 20 cases requiring pedicle screw placement (13/20 scoliosis). RESULTS Navigated interventions were performed with a median total time of 379 min per procedure (range 232-548 min for 4-24 implanted pedicle screws). The total procedure time was subdivided into surgical exposure (28%), cone beam computed tomography imaging and 3D segmentation (2%), software planning (6%), navigated surgery for screw placement (17%) and non-navigated instrumentation, wound closure, etc (47%). CONCLUSION Intraoperative imaging and preparation for surgical navigation totaled 8% of the surgical time. Consequently, ARSN can routinely be used to perform highly accurate surgery potentially decreasing the risk for complications and revision surgery while minimizing radiation exposure to the staff.

Three-dimensional fluoroscopy-guided percutaneous thoracolumbar pedicle screw placement

2003 ◽  
Vol 99 (3) ◽  
pp. 324-329 ◽  
Author(s):  
Langston T. Holly ◽  
Kevin T. Foley
Keyword(s):  
Pedicle Screw ◽  
Three Dimensional ◽  
Pedicle Screws ◽  
Screw Placement ◽  
Content Type ◽  
Image Guided ◽  
Spinal Navigation ◽  
Mean Diameter ◽  
The Mean ◽  
Fine Print

✓ The authors sought to evaluate the feasibility and accuracy of three-dimensional (3D) fluoroscopic guidance for percutaneous placement of thoracic and lumbar pedicle screws in three cadaveric specimens. After attaching a percutaneous dynamic reference array to the surgical anatomy, an isocentric C-arm fluoroscope was used to obtain images of the region of interest. Light-emitting diodes attached to the C-arm unit were tracked using an electrooptical camera. The image data set was transferred to the image-guided workstation, which performed an automated registration. Using the workstation display, pedicle screw trajectories were planned. An image-guided drill guide was passed through a stab incision, and this was followed by sequential image-guided pedicle drilling, tapping, and screw placement. Pedicle screws of various diameters (range 4–6.5 mm) were placed in all pedicles greater than 4 mm in diameter. Postoperatively, thin-cut computerized tomography scans were obtained to determine the accuracy of screw placement. Eighty-nine (94.7%) of 94 percutaneous screws were placed completely within the cortical pedicle margins, including all 30 lumbar screws (100%) and 59 (92%) of 64 thoracic screws. The mean diameter of all thoracic pedicles was 6 mm (range 2.9–11 mm); the mean diameter of the five pedicles in which wall violations occurred was 4.6 mm (range 4.1–6.3 mm). Two of the violations were less than 2 mm beyond the cortex; the others were between 2 and 3 mm. Coupled with an image guidance system, 3D fluoroscopy allows highly accurate spinal navigation. Results of this study suggest that this technology will facilitate the application of minimally invasive techniques to the field of spine surgery.

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