Thoracolumbar instrumentation with CT-guided navigation (O-arm) in 270 consecutive patients: accuracy rates and lessons learned

Top 25 Most Cited Articles on Intraoperative Computer Tomography-Guided Navigation in Spine Surgery

BACKGROUND

In recent years, the use of intraoperative computer tomography-guided (CT-guided) navigation has gained significant popularity among health care providers who perform minimally invasive spine surgery. This review aims to identify and analyze trends in the literature related to the widespread adoption of CT-guided navigation in spine surgery, emphasizing the shift from conventional fluoroscopy-based techniques to CT-guided navigation.

METHODS

Articles pertaining to this study were identified via a database review and were hierarchically organized based on the number of citations. An "advanced document search" was performed on September 28th, 2022, utilizing Boolean search operator terms. The 25 most referenced articles were combined into a primary list after sorting results in descending order based on the total number of citations.

RESULTS

The "Top 25" list for intraoperative CT-guided navigation in spine surgery cumulatively received a total of 2742 citations, with an average of 12 new citations annually. The number of citations ranged from 246 for the most cited article to 60 for the 25th most cited article. The most cited article was a paper by Siewerdsen et al., with 246 total citations, averaging 15 new citations per year.

CONCLUSIONS

Intraoperative CT-guided navigation is 1 of many technological advances that is used to increase surgical accuracy, and it has become an increasingly popular alternative to conventional fluoroscopy-based techniques. Given the increasing adoption of intraoperative CT-guided navigation in spine surgery, this review provides impactful evidence for its utility in spine surgery.

Comparison of 3D-navigation and fluoroscopic guidance in percutaneous pedicle screw placement for traumatic fractures of the thoracolumbar junction

Introduction

Fractures of the thoracolumbar junction are the most common vertebral fractures and can require surgical treatment. Several studies have shown that the accuracy of pedicle screw placement can be improved by the use of 3D-navigation. Still only few studies have focused on the use of navigation in traumatic spine injuries.

Research question

The aim of this study was to compare the screw placement accuracy and radiation exposure for 3D-navigated and fluoroscopy-guided percutaneous pedicle screw placement in traumatic fractures of the thoracolumbar junction.

Materials and methods

In this single-center study 25 patients undergoing 3D-navigated percutaneous pedicle screw placement for traumatic fractures of the thoracolumbar junction (T12-L2) were compared to a control group of 25 patients using fluoroscopy. Screw accuracy was determined in postoperative CT-scans using the Gertzbein-Robbins classification system. Additionally, duration of surgery, dose area product, fluoroscopy time and intraoperative complications were compared between the groups.

Results

The accuracy of 3D-navigated percutaneous pedicle screw placement was 92.66 % while an accuracy of 88.08 % was achieved using standard fluoroscopy (p = 0.19). The fluoroscopy time was significantly less in the navigation group compared to the control group (p = 0.0002). There were no significant differences in radiation exposure, duration of surgery or intraoperative complications between the groups.

Discussion and conclusion

The results suggest that 3D-navigation facilitates higher accuracy in percutaneous pedicle screw placement of traumatic fractures of the thoracolumbar junction, although limitations should be considered. In this study 3D-navigation did not increase fluoroscopy time, while radiation exposure and surgery time were comparable.

Surgical Management of Primary Thoracic Epidural Melanoma

In this study, we reported one of the first cases where a rare robotic-assisted platform with neuronavigation technology and carbon-fiber-polyetheretherketone (CF/PEEK) screws is employed to surgically treat multilevel thoracic primary spinal epidural melanoma. A 67-year-old male presented with left upper thoracic pain. His magnetic resonance imaging (MRI) of the thoracic spine revealed a dumbbell-shaped left epidural mass at the T2-3 level. Partial resection was performed due to tumor growth into the vertebral bodies and patient discretion for minimal surgery. The patient's neurological conditions improved postoperatively, with reduced reported symptoms of pain and numbness. Postoperative imaging showed evidence of appropriate spinal stabilization. Patient underwent stereotactic body radiation therapy (SBRT), and no adverse events were reported. This case reflects one of the first examples of treating thoracic epidural melanoma with the use of robotic-assisted navigation. Further prospective studies are needed to determine the efficacy of robot-assisted navigation for patients with primary spinal malignant melanoma which may open the possibility of surgery to once presumed non-operative patients.

Learning curve across 2000 thoracolumbar pedicle screw placements using O-arm navigation: technical difficulties and their solutions

INTRODUCTION

Instrumentation using the intraoperative O-arm navigation technique appears safer than its predecessor techniques. However, only a handful of surgeons often used navigation during spinal surgeries. Too many operative glitches and unreliable navigation accuracy were the important reasons cited even by experienced surgeons for not using spinal navigation. We have studied the accuracy of pedicle screw placement during the learning curve and beyond it. We have also discussed in detail the intricacies of the technique and solutions to the difficulties encountered using spinal navigation.

MATERIALS AND METHODS

A total of 2000 thoracolumbar pedicle screws have been placed in the 324 spine surgeries meeting the inclusion and exclusion criteria included in this retrospective study. We have divided 2000 pedicle screw placements into consecutive groups of 200 each. We have compared these groups for the accuracy of screw placement with the surgeon's experience.

RESULTS

The accuracy of pedicle screw placement using the "in-versus-out" grading system in group 1 was 85.5% which significantly increased in group 2 to 93.5% (p-value: 0.0099), and thereafter, there was a nonsignificant increase in subsequent groups with the graph achieving the shape of a plateau.

CONCLUSION

Surgeons should learn the correct principles of the technique of O-arm navigation to prevent the loss of accuracy and place pedicle screws with high accuracy. There is a learning curve of around 30-35 surgeries or 200 pedicle screw placements to acclimatize with the technique of O-arm navigation and learn its principles.

Assessing the Accuracy of Spinal Instrumentation Using Augmented Reality (AR): A Systematic Review of the Literature and Meta-Analysis

Technological advancements, particularly in the realm of augmented reality (AR), may facilitate more accurate and precise pedicle screw placement. AR integrates virtual data into the operator's real-world view, allowing for the visualization of patient-specific anatomy and navigated trajectories. We aimed to conduct a meta-analysis of the accuracy of pedicle screw placement using AR-based systems. A systematic review of the literature and meta-analysis was performed using the PubMed/MEDLINE database, including studies reporting the accuracy of pedicle screw placement using AR. In total, 8 studies with 163 patients and 1259 screws were included in the analysis. XVision (XVS) was the most commonly used AR system (595 screws) followed by the Allura AR surgical navigation system (ARSN) (462 screws). The overall accuracy was calculated as 97.2% (95% CI 96.2-98.1% p < 0.001). Subgroup analysis revealed that there was no statistically significant difference in the accuracy rates achieved by XVS and Allura ARSN (p = 0.092). AR enables reliable, accurate placement of spinal instrumentation. Future research efforts should focus on comparative studies, cost effectiveness, operative time, and radiation exposure.

Impact of Navigation on 30-Day Outcomes for Adult Spinal Deformity Surgery

STUDY DESIGN

Retrospective database study.

OBJECTIVE

Navigation has been increasingly used to treat degenerative disease, with positive radiographic and clinical outcomes and fewer adverse events and reoperations, despite increased operative time. However, short-term analysis on treating adult spinal deformity (ASD) surgery with navigation is limited, particularly using large nationally represented cohorts. This is the first large-scale database study to compare 30-day readmission, reoperation, morbidity, and value-per-operative time for navigated and conventional ASD surgery.

METHODS

Adults were identified in the National Surgical Quality Improvement Program (NSQIP) database. Multivariate regression was used to compare outcomes between navigated and conventional surgery and to control for predictors and baseline differences.

RESULTS

3190 ASD patients were included. Navigated and conventional patients were similar. Navigated cases had greater operative time (405 vs 320 min) and mean RVUs per case (81.3 vs 69.7), and had more supplementary pelvic fixations (26.1 vs 13.4%) and osteotomies (50.3 vs 27.7%) (P <.001).In univariate analysis, navigation had greater reoperation (9.9 vs 5.2%, P = .011), morbidity (57.8 vs 46.8%, P = .007), and transfusion (52.2 vs 41.8%, P = .010) rates. Readmission was similar (11.9 vs 8.4%). In multivariate analysis, navigation predicted reoperation (OR = 1.792, P = .048), but no longer predicted morbidity or transfusion. Most reoperations were infectious and hardware-related.

CONCLUSIONS

Despite controlling for patient-related and procedural factors, navigation independently predicted a 79% increased odds of reoperation but did not predict morbidity or transfusion. Readmission was similar between groups. This is explained, in part, by greater operative time and transfusion, which are risk factors for infection. Reoperation most frequently occurred for wound- and hardware-related reasons, suggesting navigation carries an increased risk of infectious-related events beyond increased operative time.

Using a 3D Navigation Template to Increase the Accuracy of Thoracic Pedicle Screws in Patients with Scoliosis

This study compares the accuracy and safety of pedicle screw placement using a 3D navigation template with the free-hand fluoroscopy technique in scoliotic patients. Fifteen scoliotic patients were recruited and divided into a template group (eight cases) and a free-hand group (seven cases). All patients received posterior corrective surgeries, and the pedicle screw was placed using a 3D navigation template or a free-hand technique. After surgery, the positions of the pedicle screws were evaluated using CT. A total of 264 pedicle screws were implanted in 15 patients. Both the two techniques were found to achieve satisfactory safety of screw insertion in scoliotic patients (89.9% vs. 90.5%). In the thoracic region, the 3D navigation template was able to achieve a much higher accuracy of screw than the free-hand technique (75.3% vs. 60.4%). In the two groups, the accuracy rates on the convex side were slightly higher than on the concave side, while no significance was seen. In terms of rotational vertebrae, no significant differences were seen in Grades I or II vertebrae between the two groups. In conclusion, the 3D navigation template technique significantly increased the accuracy of thoracic pedicle screw placement, which held great potential for extensively clinical application.

Comparative Study on Accuracy of Intra-Operative Computed Tomography-Navigation Based Pedicle Screw Placement With Skin vs Bone Fixed Dynamic Reference Frame in Minimally Invasive Transforaminal Lumbar Interbody Fusion

STUDY DESIGN

Retrospective comparative study.

OBJECTIVE

To compare the accuracy of intra-operative navigation-assisted percutaneous pedicle screw insertion between bone fixed and skin fixed dynamic reference frame (DRF) in Minimally invasive transforaminal lumbar interbody fusion (MIS-TLIF).

METHODS

Between October 2018 and September 2022, patients who underwent MIS-TLIF were included in this study with DRF fixed either on bone (group B) or skin (group S). Pedicle screws were inserted under the guidance of intra-operative Cone bean Computed tomography (cbCT) based navigation. Accuracy of pedicle screw placement was immediately checked by a final intra-operative cbCT Spin.

RESULTS

Among 170 patients, group B included 91 patients and group S included 79 patients. Out of total 680 screws, 364 screws (group B) and 316 screws (group S) were placed. Patient's demographic data and distribution of screws showed no statistically significant difference. The accuracy showed no significant difference between both the groups (94.5% in group B and 94.3% in group S).

CONCLUSION

Skin fixed DRF can serve as an alternate way for placement and avoids extra incision with similar accuracy in pedicle screw insertions with bone fixed DRF using intra-operative CT guided navigation in MIS TLIF.

Risk Factors for the Drift Phenomenon in O-arm Navigation-Assisted Pedicle Screw Placement during Spinal Deformity Surgery

OBJECTIVE

Intraoperative O-arm navigation systems improve the accuracy of spinal instrumentation placement. However, deviation of the pedicle screw from the guide line might occur. The aim of the present study was to explore the causes of and countermeasures for the drift phenomenon during pedicle screw implantation with the aid of an O-arm three-dimensional navigation system in spinal deformity surgery.

METHODS

This was a retrospective analysis of 341 patients with spinal deformity who underwent O-arm navigation system-assisted pedicle screw placement from July 2015 to June 2019. The patient's general condition, Cobb angle, apical vertebra position, softness index, spinal release status, fixed reference frame position, and distance between the navigation vertebral body and the reference frame were collected and compared by independent-samples t test or Pearson's chi-square analysis. The potential risk factors for the drift phenomenon were identified using binary logistic regression analysis.

RESULTS

The drift phenomenon occurred in 57 patients during the first navigation-assisted pedicle screw placement, for an incidence of 16.7% (57/341). There were significant differences in factors such as the apical vertebra position, softness index, spinal release status, and distance between the vertebral body and the reference frame when the drift phenomenon occurred (P < 0.05). Binary logistic regression analysis showed that the softness index, spinal release status, and distance between the vertebral body and the reference frame when drifting occurred were independent risk factors for the drift phenomenon during O-arm navigation-assisted pedicle screw placement.

CONCLUSION

During the use of an O-arm navigation system to assist with pedicle screw placement, pedicle screws should not be placed away from the reference frame, and spinal osteotomy and release should be performed after pedicle screw placement. In addition, the accuracy of O-arm navigation-assisted pedicle screw placement will be affected more in those with larger softness indices.

A systematic comparison of the accuracy of monocular RGB tracking and LiDAR for neuronavigation

With the advent of augmented reality (AR), the use of AR-guided systems in the field of medicine has gained traction. However, the wide-scale adaptation of these systems requires highly accurate and reliable tracking. In this work, the tracking accuracy of two technology platforms, LiDAR and Vuforia, are developed and rigorously tested for a catheter placement neurological procedure. Several experiments (900) are performed for each technology across various combinations of catheter lengths and insertion trajectories. This analysis shows that the LiDAR platform outperformed Vuforia; which is the state-of-the-art in monocular RGB tracking solutions. LiDAR had 75% less radial distance error and 26% less angle deviation error. Results provide key insights into the value and utility of LiDAR-based tracking in AR guidance systems.

Accuracy and Safety of Neuronavigation for Minimally Invasive Stabilization in the Thoracolumbar Spine Using Polyaxial Screws-Rod: A Canine Cadaveric Proof of Concept

OBJECTIVES

 The main aim of this study was to evaluate the feasibility of minimally invasive stabilization with polyaxial screws-rod using neuronavigation and to assess accuracy and safety of percutaneous drilling of screw corridors using neuronavigation in thoracolumbar spine and compare it between an experienced and a novice surgeon.

STUDY DESIGN

 Feasibility of minimally invasive polyaxial screws-rod fixation using neuronavigation was first performed in the thoracolumbar spine of two dogs. Accuracy and safety of drilling screw corridors percutaneously by two surgeons from T8 to L7 in a large breed dog using neuronavigation were established by comparing entry and exit points coordinates deviations on multiplanar reconstructions between preoperative and postoperative datasets and using a vertebral cortical breach grading scheme.

RESULTS

 Feasibility of minimally invasive stabilization was demonstrated. For the experienced surgeon, safety was 100% and mean (standard deviation) entry point deviations were 0.3 mm (0.8 mm) lateral, 1.3 mm (0.8 mm) ventral and 0.7 mm (1.8 mm) caudal. The exit points deviations were 0.8 mm (1.9 mm) lateral, 0.02 mm (0.9 mm) dorsal and 0.7 mm (2.0 mm) caudal. Significant difference in accuracy between surgeons was found in the thoracic region but not in the lumbar region. Accuracy and safety improvement are noted for the thoracic region when procedures were repeated by the novice.

CONCLUSION

 This proof of concept demonstrates that using neuronavigation, minimally invasive stabilization with polyaxial screws-rod is feasible and safe in a large breed dog model.

Workflow and performance of intraoperative CT, cone-beam CT, and robotic cone-beam CT for spinal navigation in 503 consecutive patients

OBJECTIVE

A direct comparison of intraoperative CT (iCT), cone-beam CT (CBCT), and robotic cone-beam CT (rCBCT) has been necessary to identify the ideal imaging solution for each individual user's need. Herein, the authors sought to analyze workflow, handling, and performance of iCT, CBCT, and rCBCT imaging for navigated pedicle screw instrumentation across the entire spine performed within the same surgical environment by the same group of surgeons.

METHODS

Between 2014 and 2018, 503 consecutive patients received 2673 navigated pedicle screws using iCT (n = 1219), CBCT (n = 646), or rCBCT (n = 808) imaging during the first 24 months after the acquisition of each modality. Clinical and demographic data, workflow, handling, and screw assessment and accuracy were analyzed.

RESULTS

Intraoperative CT showed image quality and workflow advantages for cervicothoracic cases, obese patients, and long-segment instrumentation, whereas CBCT and rCBCT offered independent handling, around-the-clock availability, and the option of performing 2D fluoroscopy. All modalities permitted reliable intraoperative screw assessment. Navigated screw revision was possible with each modality and yielded final accuracy rates > 92% in all groups (iCT 96.2% vs CBCT 92.3%, p < 0.001) without a difference in the accuracy of cervical pedicle screw placement or the rate of secondary screw revision surgeries.

CONCLUSIONS

Continuous training and an individual setup of iCT, CBCT, and rCBCT has been shown to permit safe and precise navigated posterior instrumentation across the entire spine with reliable screw assessment and the option of immediate revision. The perceived higher image quality and larger scan area of iCT should be weighed against the around-the-clock availability of CBCT and rCBCT technology with the option of single-handed robotic image acquisition.

Clinical efficiency of operating room-based sliding gantry CT as compared to mobile cone-beam CT-based navigated pedicle screw placement in 853 patients and 6733 screws

PURPOSE

Multiple solutions for navigation-guided pedicle screw placement are available. However, the efficiency with regard to clinical and resource implications has not yet been analyzed. The present study's aim was to analyze whether an operating room sliding gantry CT (ORCT)-based approach for spinal instrumentation is more efficient than a mobile cone-beam CT (CBCT)-based approach.

METHODS

This cohort study included a random sample of 853 patients who underwent spinal instrumentation using ORCT-based or CBCT-based pedicle screw placement due to tumor, degenerative, trauma, infection, or deformity disorders between November 2015 and January 2020.

RESULTS

More screws had to be revised intraoperatively in the CBCT group due to insufficient placement (ORCT: 98, 2.8% vs. CBCT: 128, 4.0%; p = 0.0081). The mean time of patients inside the OR (Interval 5 Entry-Exit) was significantly shorter for the ORCT group (ORCT: mean, [95% CI] 256.0, [247.8, 264.3] min, CBCT: 283.0, [274.4, 291.5] min; p < 0.0001) based on shorter times for Interval 2 Positioning-Incision (ORCT: 18.8, [18.1, 19.9] min, CBCT: 33.6, [32.2, 35.5] min; p < 0.0001) and Interval 4 Suture-Exit (ORCT: 24.3, [23.6, 26.1] min, CBCT: 29.3, [27.5, 30.7] min; p < 0.0001).

CONCLUSIONS

The choice of imaging technology for navigated pedicle screw placement has significant impact on standard spine procedures even in a high-volume spine center with daily routine in such devices. Particularly with regard to the duration of surgeries, the shorter time needed for preparation and de-positioning in the ORCT group made the main difference, while the accuracy was even higher for the ORCT.

Accuracy of Pedicle Screw Placement Using Intraoperative CT-Guided Navigation and Conventional Fluoroscopy for Lumbar Spondylosis

Background

Transpedicular screws are a common adjunct for lumbar spine fusion. Accurate screw placement to prevent neurological injury has been the subject of many studies. The adoption of spine neuronavigation has shown a significant decrease in screw malposition morbidity. We aim to evaluate the accuracy of pedicle screw insertion using intraoperative CT-guided navigation in lumbar spondylosis.

Methods

We reviewed a prospective registry-based cohort study. This included patients who underwent transpedicular screws insertion for lumbar spondylosis under intraoperative CT-guided navigation (iCT-Nav) and compared it to another group operated using conventional fluoroscopy (FS) over one year. In addition, the correlation between clinical outcome using the visual analog scale (VAS) and short 12 physical component scores (SF-12 PCS) and hospital stay was reported.

Results

Fifteen patients were included in the iCT-Nav group compared to 42 patients in the FS group. The median age of the iCT-Nav group was 59.3 years old (27-76 years) versus 45 years old (20-60 years) in the FS group. The number of screws was 98 in the iCT-Nav group and 252 screws in the FS group. Based on more than 2-mm breach increments measured on CT images, lumbar pedicular screw placement accuracy was 100% in the iCT-Nav group and 86.9% in the FS group. None of the patients in the iCT-Nav group had to undergo any postoperative revisions. On the other hand, two patients of the FS group developed new postoperative symptoms related to displaced screws and required readmission and revision surgery.

Conclusion

In a commonly performed pedicular fixation in lumbar spondylosis, iCT-Nav has been shown to improve the accuracy of pedicle screw placement, hospital stay, and functional outcomes compared to FS. 

Elastic Image Fusion Software to Coregister Preoperatively Planned Pedicle Screws With Intraoperative Computed Tomography Data for Image-Guided Spinal Surgery

BACKGROUND

For complex spinal cases, especially when robotic guidance is used, preoperative planning of pedicle screws can be helpful. Transfer of these preoperatively planned pedicle screws to intraoperative 3-dimensional imaging is challenging because of changes in anatomic alignment between preoperative supine and intraoperative prone imaging, especially when multiple levels are involved. In the spine, where each individual vertebra is subject to independent movement from adjacent level, rigid image fusion is confined to a single vertebra and can display fusion inaccuracies on adjacent levels. A novel elastic fusion algorithm is introduced to overcome these disadvantages. This study aimed to investigate image registration accuracy of preoperatively planned pedicle screws with an elastic fusion algorithm vs. rigid fusion for intraoperative placement with image-guided surgery.

METHODS

A total of 12 patients, were selected depending on the availability of a preoperative spinal computed tomography (CT) and an intraoperative AIRO CT scan (BrainLAB AG, Munich, Germany) of the same spinal region. To verify accuracy differences between rigid fusion and elastic fusion 76 bilateral screw trajectories were virtually defined in the preoperative CT image, and they were transferred via either rigid fusion or elastic fusion to the intraoperative CT scan. Accuracy of the transferred screws in the rigid and elastic fusion group was determined by measuring pedicle breaches on the intraoperative CT.

RESULTS

In the rigid fusion group 1.3% of screws showed a breach of less than 2 mm, 9.2% showed breaches between 2 and 4 mm, and 18.4% of the screws showed an error above 4 mm. The elastic fusion group showed no breaches and provided high accuracy between preoperative and intraoperative screw placement.

CONCLUSION

Elastic fusion provides high registration accuracy and represents a considerable step towards efficiency and safety in CT-based image-guided surgery.

LEVEL OF EVIDENCE

3.

Clinical and Radiologic Outcomes of Thoracolumbar Fusions Using Intraoperative CT Guidance and Stereotactic Navigation in a Spinal Trauma Population: An Analysis of 58 Patients

STUDY DESIGN

Retrospective review of prospectively collected single-institution database.

OBJECTIVE

To analyze the clinical and radiographic outcomes of posterior thoracolumbar fusions using intraoperative computed tomography (CT)-guidance and stereotactic navigation in thoracolumbar spinal trauma.

SUMMARY OF BACKGROUND DATA

Pedicle screw instrumentation is utilized for stabilization in thoracolumbar fusions. Suboptimal placement may lead to neurovascular complications, pseudarthrosis, postoperative pain, and the need for revision surgery. Image-guided spinal surgery is commonly used to improve accuracy, particularly for complex anatomy such as encountered with traumatic fractures.

METHODS

We retrospectively identified 58 patients undergoing posterior thoracolumbar fusions using intraoperative CT and stereotactic navigation for traumatic fractures from 2010 to 2017 at a single institution. Pedicle screw accuracy, realignment, clinical outcomes, and ease of use were retrospectively reviewed. Accuracy was assessed on postplacement or postoperative CT. Breach grades included: grade 1 (<2 mm), grade 2 (2-4 mm), and grade 3 (>4 mm).

RESULTS

A total of 58 patients were identified having undergone 58 operations, which involved placement of 519 pedicle screws. Traumatic fracture patterns and levels of injury were varied. Accurate pedicle screw placement was found in 95.8% and was stable over time. Breach included: grade 1 in 19 screws, grade 2 in 2 screws, and grade 3 in 1 screw. No neurovascular complications were noted. No revision surgery was performed for misplacement. A subgroup of 6 ankylosing spondylitis patients were identified having undergone 6 operations with 63 pedicle screws. Accurate pedicle screw placement was found in 93.7%.

CONCLUSION

Intraoperative CT-guidance and stereotactic navigation can overcome the difficulty associated with thoracolumbar trauma resulting in complex anatomy with malalignment and unpredictable trajectories. Intraoperative CT can be used with stereotactic guidance or for intraoperative verification of free-hand screw placement with repositioning as needed. CT-guidance maintains the benefit of reduced fluoroscopic exposure while improving accuracy of instrumentation and reducing reoperation for screw malposition.

Use of Intraoperative Computed Tomography Improves Outcome of Minimally Invasive Transforaminal Lumbar Interbody Fusion: A Single-Center Retrospective Cohort Study

OBJECTIVE

To provide data about surgical workflow, accuracy, complications, radiation exposure, and learning curve effect in patients who underwent minimally invasive (MIS) transforaminal lumbar interbody fusion with navigation coupled with mobile intraoperative computed tomography.

METHODS

A retrospective analysis was performed of data from consecutive patients who underwent single- or double-level MIS transforaminal lumbar interbody fusion at a single institution; mobile intraoperative computed tomography combined with a navigation system was used as the sole intraoperative imaging method to place pedicular screws; decompression and interbody fusion were performed through a 22-mm tubular retractor. Clinical data, perioperative complications, accuracy of pedicular screw placement, and radiation exposure were analyzed. A learning curve effect on surgical time and accuracy was assessed.

RESULTS

A total of 408 screws in 100 patients were analyzed. In all cases, spinal navigation allowed for identification of pedicular trajectories and greatly facilitated nerve root decompression through the MIS approach. Overall accuracy according to Heary classification was 95.3%. Nineteen screws (4.7%) presented a minor lateral breach (<2 mm), not clinically significant. Surgical time, blood loss, and patient radiation exposure compared favorably with reported values from other series using three-dimensional navigation. A learning curve effect on surgical time, but not on screw accuracy, was identified.

CONCLUSIONS

MIS transforaminal lumbar interbody fusion can now be performed without any radiation exposure to the surgeon and operating room staff, with almost absolute accuracy during screw positioning and tubular decompression. A learning curve effect on surgical time, but not on overall screw accuracy, may be expected.

Metal artifacts in intraoperative O-arm CBCT scans

Background

Cone-beam computed tomography (CBCT) has become an increasingly important medical imaging modality in orthopedic operating rooms. Metal implants and related image artifacts create challenges for image quality optimization in CBCT. The purpose of this study was to develop a robust and quantitative method for the comprehensive determination of metal artifacts in novel CBCT applications.

Methods

The image quality of an O-arm CBCT device was assessed with an anthropomorphic pelvis phantom in the presence of metal implants. Three different kilovoltage and two different exposure settings were used to scan the phantom both with and without the presence of metal rods.

Results

The amount of metal artifact was related to the applied CBCT imaging protocol parameters. The size of the artifact was moderate with all imaging settings. The highest applied kilovoltage and exposure level distinctly increased artifact severity.

Conclusions

The developed method offers a practical and robust way to quantify metal artifacts in CBCT. Changes in imaging parameters may have nonlinear effects on image quality which are not anticipated based on physics.

Use of Navigated Ultrasonic Bone Cutting Tool for En Bloc Resection of Thoracic Chondrosarcoma: Technical Report

BACKGROUND

En bloc surgical resection with wide margins offers the best local control rates for chondrosarcoma of the spine.

OBJECTIVE

To describe the surgical technique for en bloc resection of a large thoracic chondrosarcoma using image guidance for a complex osteotomy with an ultrasonic bone cutting device (Misonix, Farmingdale, New York).

METHODS

A 2-stage procedure was performed for resection of a thoracic chondrosarcoma involving the T3-T7 vertebral bodies. During the first stage, a posterior approach, the ultrasonic bone cutter was precisely navigated to perform an intralaminar osteotomy as well as a multilevel split sagittal osteotomy through the vertebral bodies. In the second stage, a transthoracic approach was used to complete the en bloc resection of the specimen. Intraoperative frozen sections from the surgical margins were negative for tumor.

RESULTS

The ultrasonic bone cutting device was navigated based on coregistration of the intraoperative computed tomography (CT) images and preoperative magnetic resonance imaging (MRI). Real-time navigation using coregistered images enabled identification of tumor margins within the bone and adjacent soft tissue allowing precise execution of the intralaminar and multilevel split sagittal vertebral osteotomies. Surgical video demonstrates the utility of real-time navigation to properly identify the tumor margins and guide the ultrasonic bone cutting tool during the osteotomies.

CONCLUSION

We describe the use of image guidance to navigate an ultrasonic bone cutting tool for a complex en bloc resection of a multilevel thoracic spine chondrosarcoma.

3D-imaging in percutaneous spine surgery using the Surgivisio system

The Surgivisio system is a new generation of intraoperative 3D imaging, used in our institution for pedicle insertion in minimally invasive spine surgery since January 2018. The purpose of this technical note is to describe the Surgivisio system, its advantages and its limitations, in percutaneous spinal surgery. Results of the first year of use were analyzed, in a series of 29 patients, to evaluate accuracy of pedicle screw insertion, operative time and radiation exposure. On the Heary and Gertzbein classifications, 95.5% of pedicle screw placements (107/112) were rated as acceptable. Mean operative time was 29.3min per vertebra; mean radiation exposure per vertebra was 0.61 mSv. The Surgivisio system is an effective navigation tool for pedicle screw insertion in minimally invasive spinal surgery, with acceptable radiation exposure and operative time for each navigated vertebra. LEVEL OF EVIDENCE: II, prospective cohort study.

Accuracy of Thoracolumbar Pedicle Screw Insertion Based on Routine Use of Intraoperative Imaging and Navigation

Study Design

Retrospective review.

Purpose

To determine the accuracy of thoracolumbar pedicle screw insertion with the routine use of three-dimensional (3D) intraoperative imaging and navigation over a large series of screws in an Asian population.

Overview of Literature

The use of 3D intraoperative imaging and navigation in spinal surgery is aimed at improving the accuracy of pedicle screw insertion. This study analyzed 2,240 pedicle screws inserted with the routine use of intraoperative navigation. It is one of very few studies done on an Asian population with a large series of screws.

Methods

Patients who had undergone thoracolumbar pedicle screws insertion using intraoperative imaging and navigation between 2009 and 2017 were retrospectively analyzed. Computed tomography (CT) images acquired after the insertion of pedicle screws were analyzed for breach of the pedicle wall. The pedicle screw breaches were graded according to the Gertzbein classification. The breach rate and revision rate were subsequently calculated.

Results

A total of 2,240 thoracolumbar pedicle screws inserted under the guidance of intraoperative navigation were analyzed, and the accuracy of the insertion was 97.41%. The overall breach rate was 2.59%, the major breach rate was 0.94%, and the intraoperative screw revision rate was 0.7%. There was no incidence of return to the operating theater for revision of screws.

Conclusions

The routine use of 3D navigation and intraoperative CT imaging resulted in consistently accurate pedicle screw placement. This improved the safety of spinal instrumentation and helped in avoiding revision surgery for malpositioned screws.

Radiological and Clinical Differences between Tinavi Orthopedic Robot and O-Arm Navigation System in Thoracolumbar Screw Implantation for Reconstruction of Spinal Stability

Background

Pedicle screw fixation is one of the most commonly used methods in spine surgery. We introduce a surgical robot system from China based on 3-dimensional fluoroscopy imaging and compare it with the commonly used O-arm navigation system. We study the differences in accuracy, safety, and clinical effect in auxiliary pedicle screw fixation.

Material/Methods

Patients who underwent thoracolumbar internal fixation in our hospital from 2017 to 2019 were divided into a robot and navigation group according to whether surgery was assisted by the Tinavi orthopedic robot or O-arm navigation system. Imaging data of patients were searched from the image system and accuracy of screw implantation was measured by Rampersaud A to D grade classification. Deviation sagittal, deviation transversal, and facet joint violation were also measured and calculated.

Results

In total, 306 patients were included: 136 patients in the robot group with 760 screws implanted; 166 patients in the navigation group with 908 screws implanted. The accuracy of “perfect” and “clinically acceptable” pedicle screw implantation was 96.2% and 99.6%, respectively, in the robot group and 90.5% and 96.7%, respectively, in the navigation group, with a significant difference between the 2 groups (P<0.05). The sagittal and transversal deviations in the robot group were significantly less than those in the navigation group (P<0.05).

Conclusions

The Tinavi orthopedic robot can significantly improve surgical accuracy and safety of pedicle screw fixation, as compared with that of O-arm navigation technology, without increasing complications. It shows great potential in clinical application.

Pedicle Screw Insertion: Is O-Arm-Based Navigation Superior to the Conventional Freehand Technique? A Systematic Review and Meta-Analysis

BACKGROUND

Although O-arm-based navigation (ON) has been considered a better choice than the conventional freehand (FH) technique for spine surgery, clinical evidence showing the accuracy of ON compared with the FH technique is limited. The purpose of this study was to evaluate the accuracy of pedicle screw insertion under ON compared with the FH technique.

METHODS

The Cochrane Library, Ovid, Web of Science, PubMed, Embase, and CNKI online databases were searched up to January 2020. Because only a few randomized controlled trials were anticipated, prospective and retrospective comparative studies were also evaluated to compare the accuracy of pedicle screw insertion between ON and FH. Statistical analysis was performed using Stata 16.0. The primary outcomes extracted from articles that met the selection criteria were expressed as odds ratios for dichotomous outcomes with a 95% confidence interval. A χ² test and I² statistics were used to evaluate heterogeneity.

RESULTS

A total of 20 reviews were included in this meta-analysis without identifying additional studies from the references of published articles. These reviews included 1422 patients and 9982 screws. ON was used to insert 4797 pedicle screws and 5185 pedicle screws were inserted using the conventional FH technique with C-arm assistance. The meta-analysis showed that ON is significantly more accurate than FH pedicle screw insertion (odds ratio, 2.46; 95% confidence interval, 1.92-3.16; I² = 43.4%; P = 0.021). I² indicates that the studies have a moderate statistical heterogeneity; subgroup analysis decreased heterogeneity significantly.

CONCLUSIONS

Compared with conventional methods, navigation provides greater accuracy in the placement of pedicle screws, accelerates the insertion, and reduces the complications associated with screw insertion. However, it may increase exposure time to radiation, which may harm the patient's or surgeon's health.

Lumbar Percutaneous Pedicle Screw Breach Rates: A Comparison of Robotic Navigation Platform Versus Conventional Techniques

STUDY DESIGN

Cadaveric study.

SUMMARY OF BACKGROUND DATA

Pedicle screw fixation is an established means of stabilizing the thoracic and lumbar spine. However, there are associated complications including pedicle breach which can result in neurological injury, durotomy, vascular injury, and suboptimal fixation.

OBJECTIVE

The aim of this study is to determine whether use of a navigated robotic platform results in fewer pedicle breaches and the underlying reasons for any difference in pedicle breach rates.

MATERIALS AND METHODS

Ten board-certified neuro- and orthopedic spine surgeons inserted 80 percutaneous lumbar screws in 10 unembalmed human cadavers. Forty screws were inserted using conventional fluoroscopic guidance and 40 were inserted using a navigated robotic platform. None of the participating surgeons had any prior experience with navigated robotic spine surgery. At the end of the study each screw was assessed with a computed tomography scan, plain radiographs and visual inspection to determine the presence or absence of pedicle breaches.

RESULTS

Forty percent (40%) of screws inserted using conventional fluoroscopic guidance breached compared with 2.5% of screws inserted with robot assistance (P=0.00005). Lateral breaches accounted for 88.2% (15/17) of all breaches. Detailed analysis revealed that the starting point of screws that breached laterally were significantly more lateral than that of the contralateral accurate screw (P=0.016). Pedicle screw diameter, length, and angulation in the transverse plane did not differ significantly between accurate screws and those that breached (P>0.05).

CONCLUSIONS

The use of a navigated robotic platform in the present study resulted in significantly fewer pedicle breaches. This was achieved through correct starting point selection with subsequent safe pedicle screw insertion.

A new tool to improve pedicle screw placement accuracy in navigated spine surgery: a monocentric study

BACKGROUND

Navigated instrumented spine surgery is burden by a low but significant screw mispositioning risks, respectively, for the 2D imaging system from 15% to 40% and, for the 3D imaging system, ranging from 4.1% to 11.5%. The primary objective of this study was to demonstrate the efficacy of a new screw-like tool in order to further decrease pedicle screws mispositioning rate during vertebral navigated spine surgery.

METHODS

Between January and June 2019 an initial case series of 18 patients were enrolled. All patients underwent a pedicle screw fixation, both in thoracic (Th10-Th12) and lumbosacral (L1-S1) spine, using O-arm (Medtronic Navigation, Louisville, CO, USA) and StealthStation S7 surgical navigation system (Medtronic Navigation). Evaluation of pedicle screws placement accuracy using the new tool in adjunct to the classic reference frame, was performed following the Gertzbein and Robbins classification.

RESULTS

A total of 94 screws have been placed. Among them, 98.9% were completely inside cortical bone (grade A) and only 1.1% with a breach of less than 2 mm (grade B).

CONCLUSIONS

Our new "screw-like" tool coupled to the classic reference frame device could improve accuracy during navigated spine surgery and potentially reducing to zero the risks for screw mispositioning.

Ten techniques for improving navigated spinal surgery

With the identification of literature shortfalls on the techniques employed in intraoperative navigated (ION) spinal surgery, we outline a number of measures which have been synthesised into a coherent operative technique. These include positioning, dissection, management of the reference frame, the grip, the angle of attack, the drill, the template, the pedicle screw, the wire, and navigated intrathecal analgesia. Optimizing techniques to improve accuracy allow an overall reduction of the repetition of the surgical steps with its associated productivity benefits including time, cost, radiation, and safety.

Cite this article: Bone Joint J 2020;102-B(3):371–375.

Augmented reality navigation with intraoperative 3D imaging vs fluoroscopy-assisted free-hand surgery for spine fixation surgery: a matched-control study comparing accuracy

This study aimed to compare screw placement accuracy and clinical aspects between Augmented Reality Surgical Navigation (ARSN) and free-hand (FH) technique. Twenty patients underwent spine surgery with screw placement using ARSN and were matched retrospectively to a cohort of 20 FH technique cases for comparison. All ARSN and FH cases were performed by the same surgeon. Matching was based on clinical diagnosis and similar proportions of screws placed in the thoracic and lumbosacral vertebrae in both groups. Accuracy of screw placement was assessed on postoperative scans according to the Gertzbein scale and grades 0 and 1 were considered accurate. Procedure time, blood loss and length of hospital stay, were collected as secondary endpoints. A total of 262 and 288 screws were assessed in the ARSN and FH groups, respectively. The share of clinically accurate screws was significantly higher in the ARSN vs FH group (93.9% vs 89.6%, p < 0.05). The proportion of screws placed without a cortical breach was twice as high in the ARSN group compared to the FH group (63.4% vs 30.6%, p < 0.0001). No statistical difference was observed for the secondary endpoints between both groups. This matched-control study demonstrated that ARSN provided higher screw placement accuracy compared to free-hand.

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.

Using lean principles to introduce intraoperative navigation for scoliosis surgery

Aims

Intraoperative 3D navigation (ION) allows high accuracy to be achieved in spinal surgery, but poor workflow has prevented its widespread uptake. The technical demands on ION when used in patients with adolescent idiopathic scoliosis (AIS) are higher than for other more established indications. Lean principles have been applied to industry and to health care with good effects. While ensuring optimal accuracy of instrumentation and safety, the implementation of ION and its associated productivity was evaluated in this study for AIS surgery in order to enhance the workflow of this technique. The aim was to optimize the use of ION by the application of lean principles in AIS surgery.

Methods

A total of 20 consecutive patients with AIS were treated with ION corrective spinal surgery. Both qualitative and quantitative analysis was performed with real-time modifications. Operating time, scan time, dose length product (measure of CT radiation exposure), use of fluoroscopy, the influence of the reference frame, blood loss, and neuromonitoring were assessed.

Results

The greatest gains in productivity were in avoiding repeat intraoperative scans (a mean of 248 minutes for patients who had two scans, and a mean 180 minutes for those who had a single scan). Optimizing accuracy was the biggest factor influencing this, which was reliant on incremental changes to the operating setup and technique.

Conclusion

The application of lean principles to the introduction of ION for AIS surgery helps assimilate this method into the environment of the operating theatre. Data and stakeholder analysis identified a reproducible technique for using ION for AIS surgery, reducing operating time, and radiation exposure. Cite this article: Bone Joint J. 2020;102-B(1):5–10

Percutaneous short-segment pedicle instrumentation assisted with O-arm navigation in the treatment of thoracolumbar burst fractures

Object

To compare the clinical and radiological outcomes of O-arm navigation assisted percutaneous pedicle fixation and open freehand pedicle fixation in treatment of AO type A3 thoracolumbar burst fractures (TBFs) without neurological deficit.

Methods

This retrospective study involved 72 patients with type A3 TBFs who underwent O-arm navigation assisted percutaneous pedicle fixation (MIS group) or open freehand posterior pedicle fixation (OPPF group) from September 2015 to December 2017. Demographic data and clinical characteristics were comparable between these two groups before surgery. Operating time, intraoperative blood loss, and the time of hospitalisation stay were analysed. Visual analog scale (VAS) scoring and Oswestry disability index (ODI) was assessed for each patient pre- and postoperatively. Radiographic follow-up was assessed by the Local kyphosis angle (LKA), Vertebral wedge angle (VWA), and Anterior body height (ABH). The accuracy of screw placement was examined by computed tomography.

Results

The two groups were matched in terms of demographic and clinical features. Intraoperative blood loss was significantly less in the MIS group compared to the OPPF group (p < 0.05). The average time for hospitalisation stay in the MIS group was significantly shorter than OPPF group (p < 0.05). However, the operative time revealed no significant difference between two groups (p > 0.05). Meanwhile, the VAS score and ODI score in the MIS group were significantly lower than that in the OPPF group after surgery (p < 0.05). Radiographic assessments revealed no obvious difference between the 2 groups immediately after surgery or at the final follow-up (p > 0.05); The accuracy rate of pedicle screw position in the MIS group was higher than OPPF group (97.8% vs 78.5%, respectively; p < 0.001). No deep wound infection, additional surgery, implant failure, or neurological complications were recorded in either group.

Conclusions

Percutaneous short-segment pedicle instrumentation assisted with O-arm navigation represents an effective and safe alternative for type A3 TBFs. It has several advantages compared with open approach, including less blood loss, shorter hospitalisation, less postoperative pain, higher accuracy of pedicle screw placement, and faster recovery period in treating TBFs. However, it requires a longer learning curve and long-term results have to be studied in other well-designed studies.

The translational potential of this article

Percutaneous short-segment pedicle instrumentation assisted with O-arm navigation represents an effective and safe alternative for type A3 TBFs. The utilization of O-arm navigation and percutaneous pedicle screw fixation guaranteed the high accuracy of screw placement, protected staff from radiation exposure and offered benefits of minimal invasive technique.

3D Real-Time Image-Guided Navigation Spine Corpectomy with Ultrasonic Bone Cutter: Technical Note

BACKGROUND

Surgical interventions for congenital scoliosis are challenging for spine surgeons. The coordination of 3-dimensional (3D), real-time, image-guided navigation with an ultrasonic bone cutter allows surgeons to localize the affected area of the spine accurately and remove the lesion without damaging soft tissue structures. The goal of this technical paper is to report a previously undescribed method of hemivertebrectomy that combines 3D, real-time, image-guided navigation and an ultrasonic bone cutter. We highlight the feasibility and safety of this method in spinal surgery.

METHODS

Three patients with congenital scoliosis were treated with this technique. We present three illustrative cases comprising hemivertebrectomies for congenital scoliosis. Intraoperative photos demonstrating the technique are also provided.

RESULTS

All surgeries were completed without complications. The hemivertebrae were completely removed, and marked correction of congenital scoliosis was noted.

CONCLUSIONS

We believe that the combination of 3D, real-time image navigation and an ultrasonic bone cutter improves hemivertebrectomy by increasing accuracy and avoiding dura laceration, major organ damage, or potential vessel damage.

Accuracy and reliability of spinal navigation: An analysis of over 1000 pedicle screws

Purpose

To estimate the rate of pedicle screw malpositioning associated with placing pedicle screws using intraoperative computed tomography (CT)-guided spinal navigation.

Methods

We analysed the records of 219 patients who underwent pedicle screw fixation using O-arm-based navigation. Screw placement accuracy was evaluated on intraoperative CT scans acquired after pedicle screw insertion. Breaches were graded according to the Gertzbein classification (grade 0-III).

Results

Of 1152 pedicle screws included, 47 had pedicle violations noted on intraoperative CT. Pedicle screw violation was noted for 17 of 241 screws placed in the cervical spine (overall breach rate, 7.05%; 3.73% and 3.3% with grade I and II, respectively), for 11 of 300 screws placed in the thoracic spine (overall breach rate, 3.67%; 2%, 1%, and 0.67% with grade I, II, and III, respectively), and for 22 of 611 screws placed in the lumbar spine (overall breach rate, 3.6%; 2.29% and 0.82% with grade I and II, respectively). The rate of accuracy of pedicle screw fixation was 93%, 96.33%, and 96.4% for the cervical, thoracic, and lumbar spine, respectively.

Conclusions

Using O-arm-based intra-operative three-dimensional scans for navigation can improve the reliability, accuracy, and safety of pedicle screw placement, reducing the risk for reoperation and hospitalization due to implant-related complications. Further improvement may be achieved by adequate consideration of potential sources of errors.

Optical Topographic Imaging for Spinal Intraoperative 3-Dimensional Navigation in the Cervical Spine: Initial Preclinical and Clinical Feasibility

OF BACKGROUND DATA

Computer-assisted 3-dimensional navigation may guide spinal instrumentation. Optical topographic imaging (OTI) is a novel navigation technique offering comparable accuracy and significantly faster registration workflow relative to current navigation systems. It has previously been validated in open posterior thoracolumbar exposures.

OBJECTIVE

To validate the utility and accuracy of OTI in the cervical spine.

STUDY DESIGN

This is a prospective preclinical cadaveric and clinical cohort study.

METHODS

Standard midline open posterior cervical exposures were performed, with segmental OTI registration at each vertebral level. In cadaveric testing, OTI navigation guidance was used to track a drill guide for cannulating screw tracts in the lateral mass at C1, pars at C2, lateral mass at C3-6, and pedicle at C7. In clinical testing, translaminar screws at C2 were also analyzed in addition. Planned navigation trajectories were compared with screw positions on postoperative computed tomographic imaging, and quantitative navigation accuracies, in the form of absolute translational and angular deviations, were computed.

RESULTS

In cadaveric testing (mean±SD) axial and sagittal translational navigation errors were (1.66±1.18 mm) and (2.08±2.21 mm), whereas axial and sagittal angular errors were (4.11±3.79 degrees) and (6.96±5.40 degrees), respectively.In clinical validation (mean±SD) axial and sagittal translational errors were (1.92±1.37 mm) and (1.27±0.97 mm), whereas axial and sagittal angular errors were (3.68±2.59 degrees) and (3.47±2.93 degrees), respectively. These results are comparable to those achieved with OTI in open thoracolumbar approaches, as well as using current spinal neuronavigation systems in similar applications. There was no radiographic facet, canal or foraminal violations, nor any neurovascular complications.

CONCLUSIONS

OTI is a novel navigation technique allowing efficient initial and repeat registration. Accuracy even in the more mobile cervical spine is comparable to current spinal neuronavigation systems.

Three-dimensional navigation (O-arm) versus fluoroscopy in the treatment of thoracic spinal stenosis with ultrasonic bone curette: A retrospective comparative study

Three-dimensional intraoperative navigation (O-arm) has been used for many years in spinal surgeries and has significantly improved its precision and safety. This retrospective study compared the efficacy and safety of spinal cord decompression surgeries performed with O-arm navigation and fluoroscopy. The clinical data of 56 patients with thoracic spinal stenosis treated from March 2015 to April 2017 were retrospectively analyzed. Spinal decompression was performed with O-arm navigation and ultrasonic bone curette in 29 patients, and with ultrasonic bone curette and fluoroscopy in 27 patients. Patients were followed-up at postoperative 1 month, 3 months, and the last clinic visit. The neurologic functions were assessed using the Japanese Orthopaedic Association (JOA) Back Pain Evaluation Questionnaire. The accuracy of screw placement was examined using three-dimensional computed tomography (CT) on postoperative day 5. There was no significant difference in the incidences of intraoperative dural tear, nerve root injury, and spinal cord injury between the two groups. The two groups showed no significant difference in postoperative JOA scores (P > .05). The O-arm navigation group had significantly higher screw placement accuracy than the fluoroscopy group (P < .05). O-arm navigation is superior to fluoroscopy in the treatment of thoracic spinal stenosis with ultrasonic bone curette in terms of screw placement accuracy. However, the two surgical modes have similar rates of intraoperative complications and postoperative neurologic functions.

Pedicle Screw Placement Using Augmented Reality Surgical Navigation With Intraoperative 3D Imaging: A First In-Human Prospective Cohort Study

STUDY DESIGN

Prospective observational study.

OBJECTIVE

The aim of this study was to evaluate the accuracy of pedicle screw placement using augmented reality surgical navigation (ARSN) in a clinical trial.

SUMMARY OF BACKGROUND DATA

Recent cadaveric studies have shown improved accuracy for pedicle screw placement in the thoracic spine using ARSN with intraoperative 3D imaging, without the need for periprocedural x-ray. In this clinical study, we used the same system to place pedicle screws in the thoracic and lumbosacral spine of 20 patients.

METHODS

The study was performed in a hybrid operating room with an integrated ARSN system encompassing a surgical table, a motorized flat detector C-arm with intraoperative 2D/3D capabilities, integrated optical cameras for augmented reality navigation, and noninvasive patient motion tracking. Three independent reviewers assessed screw placement accuracy using the Gertzbein grading on 3D scans obtained before wound closure. In addition, the navigation time per screw placement was measured.

RESULTS

One orthopedic spinal surgeon placed 253 lumbosacral and thoracic pedicle screws on 20 consenting patients scheduled for spinal fixation surgery. An overall accuracy of 94.1% of primarily thoracic pedicle screws was achieved. No screws were deemed severely misplaced (Gertzbein grade 3). Fifteen (5.9%) screws had 2 to 4 mm breach (Gertzbein grade 2), occurring in scoliosis patients only. Thirteen of those 15 screws were larger than the pedicle in which they were placed. Two medial breaches were observed and 13 were lateral. Thirteen of the grade 2 breaches were in the thoracic spine. The average screw placement time was 5.2 ± 4.1 minutes. During the study, no device-related adverse event occurred.

CONCLUSION

ARSN can be clinically used to place thoracic and lumbosacral pedicle screws with high accuracy and with acceptable navigation time. Consequently, the risk for revision surgery and complications could be minimized.

LEVEL OF EVIDENCE

3.

Accuracy of Current Techniques for Placement of Pedicle Screws in the Spine: A Comprehensive Systematic Review and Meta-Analysis of 51,161 Screws

BACKGROUND

Pedicle screws (PSs) are routinely used for stabilization to enhance fusion in a variety of spinal diseases. Although the accuracy of different PS placement methods has been previously reported, most of these studies have been limited to 1 or 2 techniques. The purpose was to determine the current accuracy of PS placement among 4 modalities of PS insertion (freehand [FH], fluoroscopy-assisted [FA], computed tomography navigation-guided [CTNav], and robot-assisted [RA]) and analyze variables associated with screw misplacement.

METHODS

A systematic review was performed of peer-reviewed articles reporting PS accuracy of 1 technique from January 1990 to June 2018. Accuracy of PS placement, PS insertion technique, and pedicle breach (PB) data were collected. A meta-analysis was performed to estimate the overall pooled (OP) rates of PS accuracy as a primary outcome, stratified by screw insertion techniques. Potential determinants were analyzed via meta-regression analyses.

RESULTS

Seventy-eight studies with 7858 patients, 51,161 PSs, and 3614 cortical PBs were included. CTNav showed the highest PS placement accuracy compared with other techniques: OP accuracy rates were 95.5%, 93.1%, 91.5%, and 90.5%, via CTNav, FH, FA, and RA techniques, respectively. RA and CTNav were associated with the highest PS accuracy in the thoracic spine, compared with FH.

CONCLUSIONS

The OP data show that CTNav has the highest PS accuracy rates. Thoracic PSs were associated with lower accuracy rates; however, RA showed fewer breaches in the thoracic spine compared with FH and FA. Given the heterogeneity among studies, further standardized and comparative investigations are required to confirm our findings.

Accuracy of pedicle screw placement in the thoracic and lumbosacral spines using O-arm-based navigation versus conventional freehand technique

Background

The accuracy and safety of pedicle screw insertion was markedly improved with the introduction of intraoperative three-dimensional navigation system during the last decade. This study aimed to evaluate the accuracy of pedicle screw placement using O-arm-based navigation system versus conventional freehand technique.

Methods

We reviewed the accuracy of 341 thoracic (n = 173) and lumbosacral (n = 168) pedicle screws placed in 60 consecutive patients using either O-arm-based navigation or freehand technique in the Department of Neurosurgery of Beijing Tsinghua Changgung Hospital between January 2015 and June 2018. Patient-specific characteristics, treatment-related characteristics, and screw-specific accuracy were analyzed. The accuracy of pedicle screw placement was measured by Gertzbein-Robbins scale and screw grades A and B were clinically acceptable.

Results

One hundred ninety-one screws were inserted in the O-arm-based navigation group and 150 in the freehand group. One hundred eighty-three (95.81%) clinically acceptable screws were placed in the navigation group and 135 (90.00%) in the freehand group (p = 0.034). Twenty-three (6.74%) screw revisions were performed in the two groups (8 screws in the navigation group and 15 screws in the freehand group) and significant difference was observed in thoracic spine (p = 0.018), while no statistical significance was presented in lumbosacral spine (p > 0.05). Twenty-four (12.57%) screws in the navigation group and 24 (16.00%) in the freehand group violated the cortex (p > 0.05). Medial screw deviation was the most common problem in the two groups.

Conclusion

The O-arm-based navigation exhibits higher accuracy for pedicle screw insertion than the freehand insertion technique.

Single position versus lateral-then-prone positioning for lateral interbody fusion and pedicle screw fixation

Background

To compare perioperative and radiographic outcomes following lateral lumbar interbody fusions in two cohorts of patients who either underwent single position or dual position surgery.

Methods

Patients over the age of 18 with degenerative lumbar pathology who underwent a lumbar interbody fusion via lateral access from 2012-2015 from a single surgeon met inclusion criteria. Patients who underwent combined procedures, had a history of retroperitoneal surgery, or had inadequate preoperative imaging were excluded. Patients who remained in the lateral decubitus position for pedicle screw fixation [single-position (SP)] were compared to those turned prone [dual-position (DP)]. Demographics, surgical details, and perioperative outcomes were compared between groups.

Results

A total of 42 SP and 24 DP patients were analyzed. The DP group had a 44.4-minute longer operating room time compared to the SP group (P<0.001) after adjusting for the number of levels operated (P<0.001) and unilateral versus bilateral screw placement (P=0.048). Otherwise, no differences were observed in peri-operative outcomes. Lordosis was not different between groups pre-operatively (P>0.999) or post-operatively (P=0.479), and neither was the pre- to post-operative change (P=0.283).

Conclusions

Lateral pedicle screw fixation following lateral interbody fusion decreases operating room time without compromising post-operative lordosis, complication rates, or perioperative outcomes.

Learning curve analysis of 3D-fluoroscopy image-guided pedicle screw insertions in lumbar single-level fusion procedures

INTRODUCTION

The implementation of 3D-navigation in the operating theater is reported to be complex, time consuming, and radiation intense. This prospective single-center cohort study was performed to objectify these assumptions by determining navigation-related learning curves in lumbar single-level posterior fusion procedures using 3D-fluoroscopy for real-time image-guided pedicle screw (PS) insertions.

MATERIALS AND METHODS

From August 2011 through July 2016, a total of 320 navigated PSs were inserted during 80 lumbar single-level posterior fusion procedures by a single surgeon without any prior experience in image-guided surgery. PS misplacements, navigation-related pre- and intraoperative time demand, and procedural 3D-radiation dose (dose-length-product, DLP) were prospectively recorded and congregated in 16 subgroups of five consecutive procedures to evaluate improving PS insertion accuracy, decreasing navigation-related time demand, and reduction of 3D-radiation dose.

RESULTS

After PS insertion and intraoperative O-arm control scanning, 11 PS modifications were performed sporadically without showing "learning curve dependencies" (PS insertion accuracies in subgroups 96.6 ± 6.3%). Average navigation-related pre-surgical time from patient positioning on the operating table to skin incision decreased from 61 ± 6 min (subgroup 1) to 28 ± 2 min (subgroup 16, p < 0.00001). Average 3D-radiation dose per surgery declined from 919 ± 225 mGycm (subgroup 1) to 66 ± 4 mGycm (subgroup 16, p < 0.0001).

CONCLUSIONS

In newly inaugurated O-arm based image-guidance, lumbar PS insertions can be performed at constantly high accuracy, even without prior experience in navigated techniques. Navigation-related time demand decreases considerably due to accelerating workflow preceding skin incision. Procedural 3D-radiation dose is reducible to a fraction (13.2%) of a lumbar diagnostic non-contrast-enhanced computed tomography scan's radiation dose.

Use of the Airo mobile intraoperative CT system versus the O-arm for transpedicular screw fixation in the thoracic and lumbar spine: a retrospective cohort study of 263 patients

OBJECTIVE

Navigation-enabling technology such as 3D-platform (O-arm) or intraoperative mobile CT (iCT-Airo) systems for use in spinal surgery has considerably improved accuracy over that of traditional fluoroscopy-guided techniques during pedicular screw positioning. In this study, the authors compared 2 intraoperative imaging systems with navigation, available in their neurosurgical unit, in terms of the accuracy they provided for transpedicular screw fixation in the thoracic and lumbar spine.

METHODS

The authors performed a retrospective analysis of clinical and surgical data of 263 consecutive patients who underwent thoracic and lumbar spine screw placement in the same center. Data on 97 patients who underwent surgery with iCT-Airo navigation (iCT-Airo group) and 166 with O-arm navigation (O-arm group) were analyzed. Most patients underwent surgery for a degenerative or traumatic condition that involved thoracic and lumbar pedicle screw fixation using an open or percutaneous technique. The primary endpoint was the proportion of patients with at least 1 screw not correctly positioned according to the last intraoperative image. Secondary endpoints were the proportion of screws that were repositioned during surgery, the proportion of patients with a postoperative complication related to screw malposition, surgical time, and radiation exposure. A blinded radiologist graded screw positions in the last intraoperative image according to the Heary classification (grade 1–3 screws were considered correctly placed).

RESULTS

A total of 1361 screws placed in 97 patients in the iCT-Airo group (503 screws) and in 166 in the O-arm group (858 screws) were graded. Of those screws, 3 (0.6%) in the iCT-Airo group and 4 (0.5%) in the O-arm group were misplaced. No statistically significant difference in final accuracy between these 2 groups or in the subpopulation of patients who underwent percutaneous surgery was found. Three patients in the iCT-Airo group (3.1%, 95% CI 0%–6.9%) and 3 in the O-arm group (1.8%, 95% CI 0%–4.0%) had a misplaced screw (Heary grade 4 or 5). Seven (1.4%) screws in the iCT-Airo group and 37 (4.3%) in the O-arm group were repositioned intraoperatively (p = 0.003). One patient in the iCT-Airo group and 2 in the O-arm group experienced postoperative neurological deficits related to hardware malposition. The mean surgical times in both groups were similar (276 [iCT-Airo] and 279 [O-arm] minutes). The mean exposure to radiation in the iCT-Airo group was significantly lower than that in the O-arm group (15.82 vs 19.12 mSv, respectively; p = 0.02).

CONCLUSIONS

Introduction of a mobile CT scanner reduced the rate of screw repositioning, which enhanced patient safety and diminished radiation exposure for patients, but it did not improve overall accuracy compared to that of a mobile 3D platform.

Contribution of Dynamic Surgical Guidance to the Accurate Placement of Pedicle Screws in Deformity Surgery: A Retrospective Case Series

OBJECTIVE

We assessed the contribution of a dynamic surgical guidance (DSG) probe in the accurate placement of thoracic and lumbar pedicle screws (PSs) in patients with spinal deformity.

METHODS

A retrospective review was performed of 98 patients (104 procedures) with various spinal deformities, who had received posterior instrumentation with PSs inserted using either DSG or the conventional free-hand (FH) technique. A total of 882 PSs were inserted using DSG (DSG group) and 603 using the FH technique (FH group). The DSG probe was preferably chosen for large osteosyntheses and severe deformities. Two neurosurgeons, unaware of the surgical groups, reviewed all the intraoperative computed tomography scans and assessed all the PS placements.

RESULTS

Of the PSs used, 95.4% in the DSG group and 92.2% in the FH group were correctly placed (P = 0.0136). The difference in screw placement accuracy was greater at the thoracic level (DSG group, 92.5%; vs. FH group, 87.0%; P = 0.0310) than at the lumbar level (DSG group, 98.0%; vs. FH group, 95.4%; P = 0.0385). Severe (>4 mm) lateral breaches occurred in 24 cases (4.0%) in the FH group but in only 5 (0.6%) in the DSG group (P < 0.0001). No severe medial breach was observed in either group.

CONCLUSIONS

Despite having more patients with severe deformities in the DSG group, PS insertion was significantly more accurate with DSG. This technique also reduced the severe unacceptable lateral misplacement rate (>4 mm) and, consequently, the incidence of intraoperative screw revisions even in patients with severe deformities.

Increased Radiation but No Benefits in Pedicle Screw Accuracy With Navigation versus a Freehand Technique in Scoliosis Surgery

BACKGROUND

The clinical value of pedicle screws in spinal deformity surgery is well known; however, screw insertion is demanding and sometimes associated with complications. Navigation systems based on intraoperatively obtained three-dimensional (3-D) images were developed to minimize pedicle screw misplacements. However, there is a lack of data confirming superiority of navigation above other techniques. There are also concerns regarding increased radiation used during the procedure.

QUESTIONS/PURPOSES

The purposes of this study were (1) to compare accuracy of the two methods of pedicle screws placement: intraoperative 3-D image navigation versus a freehand technique in patients with idiopathic scoliosis; and (2) to assess the radiation dose received by patients with both methods.

METHODS

Between 2014 and 2016, 49 patients underwent posterior spinal fusion with all pedicle screw constructs for idiopathic scoliosis performed by two surgeons. The study design involved alternating the use of the freehand technique and navigation to position pedicle screws in consecutive patients, forming groups of 27 patients with 451 navigated screws and 22 patients with 384 screws positioned freehand. The two groups did not differ in age, sex, or magnitude of deformity. Two observers not involved in the treatment evaluated the position of the screws. The pedicle breach was assessed on intraoperatively obtained 3-D O-arm® scans according to a grading system: Grade 0 = no pedicle wall violation; Grade 1 = perforation ≤ 2 mm; Grade 2 = 2 to 4 mm; and Grade 3 = perforation > 4 mm. Grades 0 and 1 were considered properly positioned and Grades 2 and 3 represented malposition.

RESULTS

In terms of accuracy, we found no differences, with the numbers available, between the freehand and navigated groups in terms of the proportion of screws that were properly positioned (96% freehand and 96% in the navigation group, respectively; p = 0.518). Grade 3 pedicle screws were observed only in the freehand group and were all located in the upper thoracic spine. Patients undergoing navigated pedicle screw placement received a greater mean radiation dose than those whose screws were placed freehand (1071 ± 447 mGy-cm versus 391 ± 53 mGy-cm; mean difference, 680 mGy-cm; 95% confidence interval, 217-2053 mGy-cm; p < 0.001).

CONCLUSIONS

In patients with moderate idiopathic scoliosis undergoing primary surgery, we did not observe benefits of pedicle screw placement with CT-based navigation, but the patients experienced greater exposure to radiation.

LEVEL OF EVIDENCE

Level III, therapeutic study.

Accuracy of pedicle screw placement based on preoperative computed tomography versus intraoperative data set acquisition for spinal navigation system

AIM

To investigate the accuracy of pedicle screw placement based on preoperative computed tomography in comparison with intraoperative data set acquisition for spinal navigation system.

METHODS

The PubMed (MEDLINE), EMBASE, and Web of Science were systematically searched for the literature published up to September 2015. This review followed the Preferred Reporting Items for Systematic Reviews and Meta-analysis guidelines. Statistical analysis was performed using the Review Manager 5.3. The dichotomous data for the pedicle violation rate was summarized using relative risk (RR) and 95% confidence intervals (CIs) with the fixed-effects model. The level of significance was set at p < 0.05.

RESULTS

For this meta-analysis, seven studies used a total of 579 patients and 2981 screws. The results revealed that the accuracy of intraoperative data set acquisition method is significantly higher than preoperative one using 2 mm grading criteria (RR: 1.82, 95% CI: 1.09, 3.04, I² = 0%, p = 0.02). However, there was no significant difference between two kinds of methods at the 0 mm grading criteria (RR: 1.13, 95% CI: 0.88, 1.46, I² = 17%, p = 0.34). Using the 2-mm grading criteria, there was a higher accuracy of pedicle screw insertion in O-arm-assisted navigation than CT-based navigation method (RR: 1.96, 95% CI: 1.05, 3.64, I² = 0%, p = 0.03). The accuracy between CT-based navigation and two-dimensional-based navigation showed no significant difference (RR: 1.02, 95% CI: 0.35-3.03, I² = 0%, p = 0.97).

CONCLUSIONS

The intraoperative data set acquisition method may decrease the incidence of perforated screws over 2 mm but not increase the number of screws fully contained within the pedicle compared to preoperative CT-based navigation system. A significantly higher accuracy of intraoperative (O-arm) than preoperative CT-based navigation was revealed using 2 mm grading criteria.

Intraoperative Computed Tomography Versus 3D C-Arm Imaging for Navigated Spinal Instrumentation

STUDY DESIGN

A prospective case-series study and a retrospective analysis of historical patients for comparison of data.

OBJECTIVE

To compare accuracy and limitations of intraoperative computed tomography (iCT)- versus 3D C-arm-based spinal navigation for posterior pedicle screw implantation.

SUMMARY OF BACKGROUND DATA

Despite the higher accuracy of navigated compared to non-navigated pedicle screw implantation, it remains a matter of debate whether the use of iCT imaging may further benefit navigated spinal instrumentation compared to more commonly used isocentric 3D C-arm imaging.

METHODS

Between 2013 and 2016, 1527 pedicle screws were implanted in 260 patients with iCT (1219 screws) or 3D C-arm (308 screws)-based spinal navigation. Screw positioning was intraoperatively assessed by a second iCT or 3D C-arm (intraoperative accuracy). If necessary, immediate intraoperative screw revision was performed. Thereafter, a third iCT or 3D C-arm scan was performed to confirm repositioning (final accuracy). Clinical and patient data, intraoperative screw assessability, and accuracy rates were retrospectively reviewed and analyzed by an independent observer.

RESULTS

Intraoperative CT permitted immediate intraoperative assessment of each implanted screw. In contrast, 39 of the screws visualized with 3D C-arm imaging were intraoperatively not clearly assessable. Regarding the overall precision, iCT and 3D C-arm navigation yielded a comparable intraoperative accuracy (iCT 94.7% vs 3D C-arm 89.4%) and immediate correction of misplaced screws was feasible with both modalities (final accuracy: iCT 95.4% vs 3D C-arm 91.6%). Regarding the region specific performance, however, iCT-based navigation yielded significantly higher final accuracy rates in the cervical (iCT 99.5% vs 3D C-arm 88.9%, P < 0.01) and thoracic (iCT 97.7% vs 3D C-arm 88.8%, P < 0.001) regions.

CONCLUSION

Both iCT and 3D C-arm-based spinal navigation provides high pedicle screw accuracy rates. Immediate screw assessability and placement accuracy in the cervical-thoracic spine, however, appear to be limited with intraoperative 3D C-arm imaging alone.

LEVEL OF EVIDENCE

3.