Total 3D Airo® Navigation for Minimally Invasive Transforaminal Lumbar Interbody Fusion

Complications in Minimally Invasive Spine Surgery in the Last 10 Years: A Narrative Review

OBJECTIVE

Minimally invasive spine surgery (MISS) employs small incisions and advanced techniques to minimize tissue damage while achieving similar outcomes to open surgery. MISS offers benefits such as reduced blood loss, shorter hospital stays, and lower costs. This review analyzes complications associated with MISS over the last 10 years, highlighting common issues and the impact of technological advancements.

METHODS

A systematic review following PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-analyses) guidelines was conducted using PubMed, MEDLINE, Embase via OVID, and Cochrane databases, covering publications from January 2013 to March 2024. Keywords related to MISS and complications were used. Studies on adult patients undergoing MISS with tubular, uniportal, or biportal endoscopy, reporting intraoperative or postoperative complications, were included. Non-English publications, abstracts, and small case series were excluded. Data on MISS approach, patient demographics, and complications were extracted and reviewed by 2 independent researchers.

RESULTS

The search identified 880 studies, with 137 included after screening and exclusions. Key complications in cervical MISS were hematomas, transient nerve root palsy, and dural tears. In thoracic MISS, complications included cerebrospinal fluid leaks and durotomy. In lumbar MISS, common complications were incidental dural injuries, postoperative neuropathic conditions, and disc herniation recurrences. Complications varied by surgical approach.

CONCLUSION

MISS offers reduced anatomical disruption compared to open surgery, potentially decreasing nerve injury risk. However, complications such as nerve injuries, durotomies, and hardware misplacement still occur. Intraoperative neuromonitoring and advanced technologies like navigation can help mitigate these risks. Despite variability in complication rates, MISS remains a safe, effective alternative with ongoing advancements enhancing its outcomes.

High Accuracy of Three-Dimensional Navigated Kirschner-Wire-Less Single-Step Pedicle Screw System (SSPSS) in Lumbar Fusions: Comparison of Intraoperatively Planned versus Final Screw Position

(1) Background: Our team has previously introduced the Single-Step Pedicle Screw System (SSPSS), which eliminates the need for K-wires, as a safe and effective method for percutaneous minimally invasive spine (MIS) pedicle screw placement. Despite this, there are ongoing concerns about the reliability and accuracy of screw placement in MIS procedures without traditional tools like K-wires and Jamshidi needles. To address these concerns, we evaluated the accuracy of the SSPSS workflow by comparing the planned intraoperative screw trajectories with the final screw positions. Traditionally, screw placement accuracy has been assessed by grading the final screw position using postoperative CT scans. (2) Methods: We conducted a retrospective review of patients who underwent lumbar interbody fusion, using intraoperative 3D navigation for screw placement. The planned screw trajectories were saved in the navigation system during each procedure, and postoperative CT scans were used to evaluate the implanted screws. Accuracy was assessed by comparing the Gertzbein and Robbins classification scores of the planned trajectories and the final screw positions. Accuracy was defined as a final screw position matching the classification of the planned trajectory. (3) Results: Out of 206 screws, 196 (95%) were accurately placed, with no recorded complications. (4) Conclusions: The SSPSS workflow, even without K-wires and other traditional instruments, facilitates accurate and reliable pedicle screw placement.

Fusion Surgery for Lumbar Spondylolisthesis: A Systematic Review with Network Meta-Analysis of Randomized Controlled Trials

OBJECTIVE

This study aimed to systematically evaluate the optimal surgical fusion approach for lumbar spondylolisthesis, to provide the latest and most reliable evidence for future clinical practice.

METHODS

A comprehensive search of the PubMed, Ovid-Embase, Web of Science, Cochrane, and Scopus databases was conducted from inception to September 1, 2023, to identify relevant records. Two independent reviewers performed the literature screening, data extraction, and assessment of study quality.

RESULTS

Fifteen randomized controlled trials involving 892 patients met the inclusion criteria. The network evidence plot showed that posterolateral fusion and posterior lumbar interbody fusion (PLIF) were the most used fusion techniques. The network meta-analysis results revealed that minimally invasive transforaminal lumbar interbody fusion (MIS-TLIF) had a significantly greater improvement in the Oswestry Disability Index (ODI) compared to endoscopic-TLIF, while PLIF had a significantly better fusion effect than posterolateral fusion. Furthermore, no statistically significant differences were observed between other fusion surgeries in terms of improving ODI, fusion rate, complications, or the improvement of visual analog scale-low back pain. The surface under the cumulative ranking curve results indicated that MIS-TLIF had the greatest potential for improving ODI, visual analog scale-low back pain, and complications, while PLIF had the greatest potential for increasing fusion rates. However, the existing selection bias, measurement bias, reporting bias, and publication bias may have reduced the reliability of the meta-analysis results.

CONCLUSIONS

Among the various fusion surgeries for lumbar spondylolisthesis, MIS-TLIF appears to provide the greatest benefit to patients. However, more high-quality, large-scale studies are needed to further investigate the treatment efficacy of different fusion surgeries for lumbar spondylolisthesis.

Expandable cages that expand both height and lordosis provide improved immediate effect on sagittal alignment and short-term clinical outcomes following minimally invasive transforaminal lumbar interbody fusion (MIS TLIF)

Background

Failure to restore lordotic alignment is not an uncommon problem following minimally invasive transforaminal lumbar interbody fusion (MIS TLIF), even with expandable cages that increase disc height. This study aims to investigate the effect of the expandable cage that is specifically designed to expand both height and lordosis. We evaluated the outcomes of MIS TLIF in restoring immediate postoperative sagittal alignment by comparing two different types of expandable cages. One cage is designed to solely increase disc height (Group H), while the other can expand both height and lordosis (Group HL).

Methods

Patients undergoing MIS TLIF using expandable cages were retrospectively reviewed, including 40 cases in Group H and 109 cases in Group HL. Visual analog scores of back and leg pain, and Oswestry disability index were collected. Disc height, disc angle, and sagittal alignment were measured. Complications were recorded, including early subsidence which was evaluated with computed tomography.

Results

Clinical and radiographic outcomes significantly improved in both groups postoperatively. Group HL showed superior improvement in segmental lordosis (4.4°±3.5° vs. 2.1°±4.8°, P=0.01) and disc angle (6.3°±3.8 vs. 2.2°±4.3°, P<0.001) compared to Group H. Overall incidence of early subsidence was 23.3%, predominantly observed during initial cases as part of the learning curve, but decreased to 18% after completion of the first 20 cases.

Conclusions

Expandable cages with a design specifically aimed at increasing lordotic angle can provide favorable outcomes and effectively improve immediate sagittal alignment following MIS TLIF, compared to conventional cages that only increase in height. However, regardless of the type of expandable cage used, it is crucial to avoid applying excessive force to achieve greater disc height or lordosis, as this may contribute to subsidence and a possible reduction in lordotic alignment restoration. Long-term results are needed to evaluate the clinical outcome, fusion rate, and maintenance of the sagittal alignment.

Navigation-Guided/Robot-Assisted Spinal Surgery: A Review Article

The development of minimally invasive spinal surgery utilizing navigation and robotics has significantly improved the feasibility, accuracy, and efficiency of this surgery. In particular, these methods provide improved accuracy of pedicle screw placement, reduced radiation exposure, and shortened learning curves for surgeons. However, research on the clinical outcomes and cost-effectiveness of navigation and robot-assisted spinal surgery is still in its infancy. Therefore, there is limited available evidence and this makes it difficult to draw definitive conclusions regarding the long-term benefits of these technologies. In this review article, we provide a summary of the current navigation and robotic spinal surgery systems. We concluded that despite the progress that has been made in recent years, and the clear advantages these methods can provide in terms of clinical outcomes and shortened learning curves, cost-effectiveness remains an issue. Therefore, future studies are required to consider training costs, variable initial expenses, maintenance and service fees, and operating costs of these advanced platforms so that they are feasible for implementation in standard clinical practice.

Ten-step minimally invasive slalom unilateral laminotomy for bilateral decompression (sULBD) with navigation

BACKGROUND

Unilateral laminotomy for bilateral decompression (ULBD) is a MIS surgical technique that offers safe and effective decompression of lumbar spinal stenosis (LSS) with a long-term resolution of symptoms. Advantages over conventional open laminectomy include reduced expected blood loss, muscle damage, mechanical instability, and less postoperative pain. The slalom technique combined with navigation is used in multi-segmental LSS to improve the workflow and effectiveness of the procedure.

METHODS

We outline ten technical steps to achieve a slalom unilateral laminotomy for bilateral decompression (sULBD) with navigation. In a retrospective case series, we included patients with multi-segmental LSS operated in our institution using the sULBD between 2020 and 2022. The primary outcome was a reduction in pain measured by Visual Analogue Scale (VAS) for back pain and leg pain and Oswestry Disability Index (ODI).

RESULTS

In our case series (N = 7), all patients reported resolution of initial symptoms on an average follow-up of 20.71 ± 9 months. The average operative time and length of hospital stay were 196.14 min and 1.67 days, respectively. On average, VAS (back pain) was 4.71 pre-operatively and 1.50 on long-term follow-up of an average of 19.05 months. VAS (leg pain) decreased from 4.33 to 1.21. ODI was reported as 33% pre-operatively and 12% on long-term follow-up.

CONCLUSION

The sULBD with navigation is a safe and effective MIS surgical procedure and achieves the resolution of symptoms in patients presenting with multi-segmental LSS. Herein, we demonstrate the ten key steps required to perform the sULBD technique. Compared to the standard sULBD technique, the incorporation of navigation provides anatomic localization without exposure to radiation to staff for a higher safety profile along with a fast and efficient workflow.

The Use of Intraoperative CT Hounsfield Unit Values for the Assessment of Bone Quality in Patients Undergoing Lumbar Interbody Fusion

STUDY DESIGN

Retrospective Cohort Study.

OBJECTIVE

To evaluate the accuracy of intraoperatively measured computed tomography (CT) Hounsfield unit (HU) values by comparison with preoperative CT HU values and to compare the radiation exposure between preoperative and intraoperative CT scans.

METHODS

HU values of lumbar vertebrae were measured and compared between preoperative and intraoperative CT scans in patients undergoing lumbar interbody fusion. In patient group one, Canon CT scanners were used preoperatively and the AIRO CT scanner was used intraoperatively. In patient group two, Canon CT scanners were used preoperatively and the O-arm Cone Beam CT (CBCT) scanner was used intraoperatively. In a subgroup analysis of patient group one, radiation by means of CT Dose Index (CTDI) was compared between Canon and AIRO CT scanners.

RESULTS

In the first patient group, a total of 250 vertebrae were analysed in 74 patients showing a strong Pearson correlation of >.94 between pre- and intraoperative HU values. Bland-Altman analysis indicated consistency and equivalence with a bias of 3.9 and 95% limits of agreement from -27.17 to 34.97 when comparing all pre- and intraoperative HU values of L1-5. In the second patient group, a total of 27 vertebrae were analysed in 10 patients showing weak Pearson correlation and Bland-Altman analysis indicated no equivalence. CTDI did not differ between Canon and AIRO CT scanners.

CONCLUSION

Correct and reliable CT HU measurement as mandatory key factor for the intraoperative assessment of bone quality and robotic-assisted surgery is feasible with intraoperative AIRO CT imaging without increase of radiation exposure.

Microsurgical Tubular Resection of Intradural Extramedullary Spinal Tumors With 3-Dimensional-Navigated Localization

BACKGROUND

The safety and efficacy of minimally invasive spine surgical (MISS) approaches have stimulated interest in adapting MISS principles for more complex pathology including intradural extramedullary (IDEM) tumors. No study has characterized a repeatable approach integrating the MISS surgical technique and 3-dimensional intraoperative navigated localization for the treatment of IDEM tumors.

OBJECTIVE

To describe a safe and reproducible technical guide for the navigated MISS technique for the treatment of benign intradural and extradural spinal tumors.

METHODS

Retrospective review of prospectively collected data on 20 patients who underwent navigated microsurgical tubular resection of intradural extramedullary tumors over a 5-year period. We review our approach to patient selection and report demographic and outcomes data for the cohort.

RESULTS

Our experience demonstrates technical feasibility and safety with a 100% rate of gross total resection with no patients demonstrating recurrence during an average follow-up of 20.2 months and no instances of perioperative complications. We demonstrate favorable outcomes regarding blood loss, operative duration, and hospital length of stay.

CONCLUSION

Navigated localization and microsurgical tubular resection of IDEM tumors is safe and effective. Adherence to MISS principles and thoughtful patient selection facilitate successful management of these patients.

Augmented Reality to Improve Surgical Workflow in Minimally Invasive Transforaminal Lumbar Interbody Fusion - A Feasibility Study With Case Series

OBJECTIVE

Minimally invasive transforaminal lumbar interbody fusion (MIS-TLIF) is a highly reproducible procedure for the fusion of spinal segments. We recently introduced the concept of "total navigation" to improve workflow and eliminate fluoroscopy. Imageguided surgery incorporating augmented reality (AR) may further facilitate workflow. In this study, we developed and evaluated a protocol to integrate AR into the workflow of MISTLIF.

METHODS

A case series of 10 patients was the basis for the evaluation of a protocol to facilitate tubular MIS-TLIF by the application of AR. Surgical TLIF landmarks were marked on a preoperative computed tomography (CT)-scan using dedicated software. This marked CT scan was fused intraoperatively with the low-dose navigation CT scan using elastic image fusion, and the markers were transferred to the intraoperative scan. Our experience with this workflow and the surgical outcomes were collected.

RESULTS

Our AR protocol was safely implemented in all cases. The TLIF landmarks could be preoperatively planned and transferred to the intraoperative imaging. Of the 10 cases, 1 case had additionally a synovial cyst resection and in 2 cases an additional bony decompression was performed due to central stenosis. The average procedure time was 160.6 ± 31.9 minutes. The AR implementation added 1.72 ± 0.37 minutes to the overall procedure time. No complications occurred.

CONCLUSION

Our findings support the idea that total navigation with AR may further facilitate the workflow, especially in cases with more complex anatomy and for teaching and training purposes. More work is needed to simplify the software and make AR integration more user-friendly.

Navigation Techniques in Endoscopic Spine Surgery

Endoscopic spine surgery (ESS) advances the principles of minimally invasive surgery, including minor collateral tissue damage, reduced blood loss, and faster recovery times. ESS allows for direct access to the spine through small incisions and direct visualization of spinal pathology via an endoscope. While this technique has many applications, there is a steep learning curve when adopting ESS into a surgeon's practice. Two types of navigation, optical and electromagnetic, may allow for widespread utilization of ESS by engendering improved orientation to surgical anatomy and reduced complication rates. The present review discusses these two available navigation technologies and their application in endoscopic procedures by providing case examples. Furthermore, we report on the future directions of navigation within the discipline of ESS.

Multimodal Applications of 3D-Navigation in Single-Level Minimally Invasive Transforaminal Lumbar Interbody Fusion: Impacts on Precision, Accuracy, Complications, and Radiation Exposure

BACKGROUND

Three-dimensional (3D)-navigation in minimally invasive transforaminal lumbar interbody fusion (MI-TLIF) is an evolving procedure. It is used not only for its accuracy of pedicle screw fixation but also for other major steps in transforaminal lumbar interbody fusion. Multimodal outcomes of this procedure are very limited in the literature. The purpose of this study was to examine the application of 3D-navigation in minimally invasive transforaminal lumbar interbody fusion (MI-TLIF).

METHODS

Patients who underwent single-level MI-TLIF using 3D-navigation between January 2017 and July 2019 were evaluated for navigation setting time, radiation exposure, volume of nucleus pulposus excised, cage placement, accuracy of pedicle screw placement, and cranial facet-joint violation.

RESULTS

One hundred and two patients with a mean age of 60.2 years met the inclusion criteria. The mean presetting time of navigation was 46.65 ± 9.45 minutes. Radiation exposure, fluoroscopy use, and fluoroscopy time were 15.54 ± 0.65 mGy, 4.43 ± 0.87 Gy.cm², and 97.6 ± 11.67 seconds, respectively. The mean amount of nucleus pulposus excised from all quadrants was quantified. The cage was centrally placed in 87 patients, with 95.4% showing a Grade 0 pedicle breach and 94.6% showing Grade 0 cranial facet-joint violation.

CONCLUSION

Registration and setting up 3D-navigation takes additional time. The amount of exposure to the patient is much less compared to routine computed tomography, and, importantly, the operating team is protected from radiation. Navigated MI-TLIF has high rates of accuracy with regard to placement of percutaneous pedicle screws and cages with the added advantage of protection of the cranial facet-joint.

LEVEL OF EVIDENCE: 5

Challenges Hindering Widespread Adoption of Minimally Invasive Spinal Surgery

Minimally invasive spinal surgery (MISS) techniques offer several beneficial prospects and are being increasingly requested by patients. However, these techniques have not been uniformly adopted by spinal surgeons, and they remain controversial among some. Several barriers have prevented widespread adoption of MISS. These include concerns regarding high start-up costs, limited evidence base, and lack of surgeon training. In addition, the unique approaches involved in MISS expose spinal surgeons to unfamiliar anatomy. Further, while MISS can address a growing spectrum of spinal pathology, some conditions, as well as complications encountered during MISS procedures, require open surgery. This requires surgeons to not only acquire the new and specialized MISS skillset but also maintain their ability to perform open surgery. These factors present challenges common to developing and innovative surgical techniques. Here, we review the barriers preventing wider adoption of MISS and present a framework to promote the safe and effective growth of MISS.

Pedicle Screw Placement Using Intraoperative Computed Tomography and Computer-Aided Spinal Navigation Improves Screw Accuracy and Avoids Postoperative Revisions: Single-Center Analysis of 1400 Pedicle Screws

OBJECTIVE

Intraoperative computed tomography and navigation (iCT-Nav) is increasingly used to aid spinal instrumentation. We aimed to document the accuracy and revision rate of pedicle screw placement across many screws placed using iCT-Nav. We also assess patient-level factors predictive of high-grade pedicle breach.

METHODS

Medical records of patients who underwent iCT-Nav pedicle screw placement between 2015 and 2017 at a single center were retrospectively reviewed. Screw placement accuracy was individually assessed for each screw using the 2-mm incremental grading system for pedicle breach. Predictors of high-grade (>2 mm) breach were identified using multiple logistic regression.

RESULTS

In total, 1400 pedicle screws were placed in 208 patients undergoing cervicothoracic (29; 13.9%), thoracic (30; 14.4), thoracolumbar (19; 9.1%) and lumbar (130; 62.5%) surgeries. iCT-Nav afforded high-accuracy screw placement, with 1356 of 1400 screws (96.9%) being placed accurately. In total, 37 pedicle screws (2.64%) were revised intraoperatively during the index surgery across 31 patients, with no subsequent returns to the operating room because of screw malpositioning. After correcting for potential confounders, males were less likely to have a high-grade breach (odds ratio [OR] 0.21; 95% confidence interval [CI] 0.10-0.59, P = 0.003) whereas lateral (OR 6.21; 95% CI 2.47-15.52, P < 0.001) or anterior (OR 5.79; 95% CI2.11-15.88, P = 0.001) breach location were predictive of a high-grade breach.

CONCLUSIONS

iCT-Nav with postinstrumentation intraoperative imaging is associated with a reduced need for costly postoperative return to the operating room for screw revision. In comparison with studies of navigation without iCT where 1.5%-1.7% of patients returned for a second surgery, we report 0 revision surgeries due to screw malpositioning.

Surface Navigation and the Influence of Navigation on MIS Surgery

STUDY DESIGN

Literature review.

OBJECTIVES

To review the evidence for surface-based navigation in minimally-invasive spine surgery (MIS), provide an outline for its workflow, and present a wide range of MIS case examples in which surface-based navigation may be advantageous.

METHODS

A comprehensive review of the literature and compilation of findings related to surface-based navigation in MIS was performed. Workflow and case examples utilizing surface-based navigation were described.

RESULTS

The nascent literature regarding surface-based intraoperative navigation (ION) in spine surgery is encouraging and initial studies have shown that surface-based navigation can allow for accurate pedicle screw placement and decreased operative time, fluoroscopy time, and radiation exposure when compared to traditional fluoroscopic imaging. Surface-based navigation may be particularly useful in MIS cervical and lumbar decompressions and MIS lumbar instrumentation cases.

CONCLUSIONS

Overall, it is possible that surface-based ION will become a mainstay in the armamentarium of enabling technologies utilized by minimally-invasive spine surgeons, but further studies are needed assessing its accuracy, complications, and cost-effectiveness.

Time-demand, Radiation Exposure and Outcomes of Minimally Invasive Spine Surgery With the Use of Skin-Anchored Intraoperative Navigation: The Effect of the Learning Curve

STUDY DESIGN

Retrospective review.

OBJECTIVE

The aim was to evaluate the learning curve of skin-anchored intraoperative navigation (ION) for minimally invasive lumbar surgery.

SUMMARY OF BACKGROUND DATA

ION is increasingly being utilized to provide better visualization, improve accuracy, and enable less invasive procedures. The use of noninvasive skin-anchored trackers for navigation is a novel technique, with the few reports on this technique demonstrating safety, feasibility, and significant reductions in radiation exposure compared with conventional fluoroscopy. However, a commonly cited deterrent to wider adoption is the learning curve.

METHODS

Retrospective review of patients undergoing 1-level minimally invasive lumbar surgery was performed. Outcomes were: (1) time for ION set-up and image-acquisition; (2) operative time; (3) fluoroscopy time; (4) radiation dose; (5) operative complications; (6) need for repeat spin; (7) incorrect localization.Chronologic case number was plotted against each outcome. Derivative of the nonlinear curve fit to the dataset for each outcome was solved to find plateau in learning.

RESULTS

A total of 270 patients [114 microdiscectomy; 79 laminectomy; 77 minimally invasive transforaminal lumbar interbody fusion (MI-TLIF)] were included. (1) ION set-up and image-acquisition: no learning curve for microdiscectomy. Proficiency at 23 and 31 cases for laminectomy and MI-TLIF, respectively. (2) Operative time: no learning curve for microdiscectomy. Proficiency at 36 and 31 cases for laminectomy and MI-TLIF, respectively. (3) Fluoroscopy time: no learning curve. (4) Radiation dose: proficiency at 42 and 33 cases for microdiscectomy and laminectomy, respectively. No learning curve for MI-TLIF. (5) Operative complications: unable to evaluate for microdiscectomy and MI-TLIF. Proficiency at 29 cases for laminectomy. (6) Repeat spin: unable to evaluate for microdiscectomy and laminectomy. For MI-TLIF, chronology was not associated with repeat spins. (7) Incorrect localization: none.

CONCLUSIONS

Skin-anchored ION did not result in any wrong level surgeries. Learning curve for other parameters varied by surgery type, but was achieved at 25-35 cases for a majority of outcomes.

LEVEL OF EVIDENCE

Level III.

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.

Intraoperative Simulation: Team Training for Resuscitation While Using Intraoperative Computed Tomography: 2-Dimensional Operative Video

Spine surgeons increasingly use intraoperative computed tomography (iCT) to facilitate surgery. iCT has several advantages, including the ability to decrease radiation exposure, improve surgical accuracy, and decrease operative time.1-3 However, the large footprint of the equipment can impede fast patient access in the event of an emergency resuscitation. This challenge is compounded when the patient is prone with rigid head fixation. To achieve fast, high-quality resuscitation, a large team must overcome numerous challenges. Cohesive team functioning under these circumstances requires planning, practice, and refinement.4  As a result of our simulation sessions, we have made several changes to the setup of our iCT cases. The following equipment is now routinely used: extralong tubing between the anesthesia circuit and patient, portable vital monitor, additional intravenous access is obtained, and extension tubing is used with all lines. We have created educational diagrams to streamline 2 challenging processes: optimal bed placement (for supination) and removal of equipment from the operating room (OR) to accommodate an influx of emergency personnel and equipment.  Since the implementation of this protocol, 1 prone posterior cervical patient had intraoperative cardiac arrest. The protocol was followed. Return of spontaneous circulation was achieved within 5 min. The patient was discharged from the hospital with no neurological sequelae. During debriefing, stakeholders uniformly credited the simulated practice with this positive outcome.  Emergency planning is a multifaceted process that continually evolves. With a steady flux of personnel and equipment, ongoing practice is essential to ensure readiness. Here, we share the key elements of our twice-yearly simulation.  This simulation was performed on a training mannequin. This study did not involve human subjects. Any depictions of care rendered to nonidentifiable patients were standard (nonexperimental).

Image Guidance in Spinal Surgery: A Critical Appraisal and Future Directions

BACKGROUND

Image-guided spinal surgery (IGSS) underwent rapid development over the past decades. The goal of IGSS is to increase patient safety and improve workflow. We present an overview of the history of IGSS, illustrate its current state, and highlight future developments. Currently, IGSS requires an image set, a tracking system, and a calibration method.

IMAGING

Two-dimensional images have many disadvantages as a source for navigation. Currently, the most common navigation technique is three-dimensional (3D) navigation based on cross-sectional imaging techniques such as cone-beam computed tomography (CT) or fan-beam CT.

TRACKING

Electromagnetic tracking uses an electromagnetic field to localize instruments. Optical tracking using infrared cameras has currently become one of the most common tracking methods in IGSS.

CALIBRATION

The three most common techniques currently used are the point-matching registration technique, the surface-matching registration technique, and the automated registration technique.

FUTURE

Augmented reality (AR) describes a computer-generated image that can be superimposed onto the real-world environment. Marking pathologies and anatomical landmarks are a few examples of many possible future applications. Additionally, AR offers a wide range of possibilities in surgical training. The latest development in IGSS is robotic-assisted surgery (RAS). The presently available data on RAS are very encouraging, but further improvements of these procedures is expected.

CONCLUSION

IGSS significantly evolved since its inception and is becoming a routinely used technology. In the future, IGSS will combine the advantages of "active/freehand 3D navigation" with AR and RAS and will one day find its way into all aspects of spinal surgery, not only in instrumented procedures.

Minimally Invasive Transforaminal Lumbar Interbody Fusion Using Augmented Reality Surgical Navigation for Percutaneous Pedicle Screw Placement

STUDY DESIGN

This was a retrospective observational study.

OBJECTIVE

The aim of this study was to evaluate the accuracy of percutaneous pedicle screw placement using augmented reality surgical navigation during minimally invasive transforaminal lumbar interbody fusion (TLIF).

SUMMARY OF BACKGROUND DATA

Augmented reality-based navigation is a new type of computer-assisted navigation where video cameras are used instead of infrared cameras to track the operated patients and surgical instruments. This technology has not so far been clinically evaluated for percutaneous pedicle screw placement.

MATERIALS AND METHODS

The study assessed percutaneous pedicle screw placement in 20 consecutive patients who underwent single-level minimally invasive TLIF using augmented reality surgical navigation. Facet joint violation and depression by the inserted pedicle screws were evaluated. Secondary outcome such as radiation dose exposure, fluoroscopy time, and operative time were collected for 3 phases of surgery: preparation phase, pedicle screw placement, and decompression with cage placement.

RESULTS

A clinical accuracy for screw placement within the pedicle (Gertzbein 0 or 1) of 94% was achieved. One screw violated the facet joint with a transarticular pathway. The screw head did not depress the facet in 54%. The use of fluoroscopy during navigation correlated with patient body-mass index (r=0.68, P<0.0001). The pedicle screw placement time corresponded to 36±5% of the total operative time of 117±11 minutes. A statistically significant decrease of 10 minutes in operative time was observed between the first and last 10 procedures which corresponded to the pedicle screw placement time decrease (48±9 vs. 38±7 min, P=0.0142). The learning curve model suggests an ultimate operative time decrease to 97 minutes.

CONCLUSION

Augmented reality surgical navigation can be clinically used to place percutaneous screws during minimally invasive TLIF. However, the lack of tracking of the location of the device requires intraoperative fluoroscopy to monitor screw insertion depth especially in obese patients.

LEVEL OF EVIDENCE

Level III.

Radiation Exposure in Posterior Lumbar Fusion: A Comparison of CT Image-Guided Navigation, Robotic Assistance, and Intraoperative Fluoroscopy

STUDY DESIGN

Retrospective clinical review.

OBJECTIVE

To assess the use of intraoperative computed tomography (CT) image-guided navigation (IGN) and robotic assistance in posterior lumbar surgery and their relationship with patient radiation exposure and perioperative outcomes.

METHODS

Patients ≥18 years old undergoing 1- to 2-level transforaminal lateral interbody fusion in 12-month period were included. Chart review was performed for pre- and intraoperative data on radiation dose and perioperative outcomes. All radiation doses are quantified in milliGrays (mGy). Univariate analysis and multivariate logistic regression analysis were utilized for categorical variables. One-way analysis of variance with post hoc Tukey test was used for continuous variables.

RESULTS

A total of 165 patients were assessed: 12 IGN, 62 robotic, 56 open, 35 fluoroscopically guided minimally invasive surgery (MIS). There was a lower proportion of women in open and MIS groups (P = .010). There were more younger patients in the MIS group (P < .001). MIS group had the lowest mean posterior levels fused (P = .015). Total-procedure radiation, total-procedure radiation/level fused, and intraoperative radiation was the lowest in the open group and highest in the MIS group compared with IGN and robotic groups (all P < .001). Higher proportion of robotic and lower proportion of MIS patients had preoperative CT (P < .001). Estimated blood loss (P = .002) and hospital length of stay (P = .039) were lowest in the MIS group. Highest operative time was observed for IGN patients (P < .001). No differences were observed in body mass index, Charlson Comorbidity Index, and postoperative complications (P = .313, .051, and .644, respectively).

CONCLUSION

IGN and robotic assistance in posterior lumbar fusion were associated with higher intraoperative and total-procedure radiation exposure than open cases without IGN/robotics, but significantly less than MIS without IGN/robotics, without differences in perioperative outcomes. Fluoro-MIS procedures reported highest radiation exposure to patient, and of equal concern is that the proportion of total radiation dose also applied to the surgeon and operating room staff in fluoro-MIS group is higher than in IGN/robotics and open groups.

A minimally invasive lateral approach with CT navigation for open biopsy and diagnosis of Nocardia nova L4–5 discitis osteomyelitis: illustrative case

BACKGROUND

Lumbar spine osteomyelitis can be refractory to conventional techniques for identifying a causal organism. In cases in which a protracted antibiotic regimen is indicated, obtaining a conclusive yield on biopsy is particularly important. Although lateral transpsoas approaches and intraoperative computed tomography (CT) navigation are well documented as techniques used for spinal arthrodesis, their utility in vertebral biopsy has yet to be reported in any capacity.

OBSERVATIONS

In a 44-year-old male patient with a history of Nocardia bacteremia, CT-guided biopsy failed to confirm the microbiology of an L4–5 discitis osteomyelitis. The patient underwent a minimally invasive open biopsy in which a lateral approach with intraoperative guidance was used to access the infected disc space retroperitoneally. A thin film was obtained and cultured Nocardia nova, and the patient was treated accordingly with a long course of trimethoprim-sulfamethoxazole.

LESSONS

The combination of a lateral transpsoas approach with intraoperative navigation is a valuable technique for obtaining positive yield in cases of discitis osteomyelitis of the lumbar spine refractory to CT-guided biopsy.

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.

State of the art advances in minimally invasive surgery for adult spinal deformity

Adult spinal deformity (ASD) can be associated with substantial suffering due to pain and disability. Surgical intervention for achieving neural decompression and restoring physiological spinal alignment has shown to result in significant improvement in pain and disability through patient-reported outcomes. Traditional open approaches involving posterior osteotomy techniques and instrumentation are effective based on clinical outcomes but associated with high complication rates, even in the hands of the most experienced surgeons. Minimally invasive techniques may offer benefit while decreasing associated morbidity. Minimally invasive surgery (MIS) for ASD has evolved over the past 20 years, driven by improved understanding of open procedures along with novel technique development and technologic advancements. Early efforts were hindered due to suboptimal outcomes resulting from high pseudarthrosis, inadequate correction, and fixation failure rates. To address this, multi-center collaborative groups have been established to study large numbers of ASD patients which have been vital to understanding optimal patient selection and individualized management strategies. Different MIS decision-making algorithms have been described to better define appropriate candidates and interbody selection approaches in ASD. The purpose of this state of the review is to describe the evolution of MIS surgery for adult deformity with emphasis on landmark papers, and to discuss specific MIS technology for ASD, including percutaneous pedicle screw instrumentation, hyperlordotic grafts, three-dimensional navigation, and robotics.

Distinct fusion intersegmental parameters regarding local sagittal balance provide similar clinical outcomes: a comparative study of minimally invasive versus open transforaminal lumbar interbody fusion

Background

Most contemporary studies suggested that intersegmental parameters including disc height and local lordosis contribute to the sagittal balance of fused lumbar. Although similar clinical outcomes following MIS- and Open-TLIF were reported essentially at the early postoperative time, the comparison of local balance variables after these two different techniques was lack. The radiological differences maybe not relevant to the postoperative efficacy at an earlier post-operation stage. But during the long-term follow-up, the complications with regards to the sagittal imbalance might occur due to the distinct biomechanical properties of fusion level after MIS- and Open-TLIF.

Methods

The patients who underwent a single-level MIS- and Open-TLIF were reviewed retrospectively. The anterior disc height (ADH), posterior disc height (PDH), and segmental lordosis (SL) of the fusion segment were measured using recognition technical fluoroscopy. The mean disc height (MDH) was calculated by (ADH + PDH)/2. The relative DH was normalized by the anterior height of the upper vertebrae. The body mass index (BMI), the pain score of low back and leg visual analogue scale (VAS), Oswestry disability index (ODI), estimated blood loss, and hospital stay length was collected.

Results

A total of 88 patients undergoing a single-level TLIF (MIS and Open) were included. The pre- and post-operative ADH, PDH, MDH, and SL of MIS-TLIF group were 1.57 ± 0.33 cm, 0.79 ± 0.20 cm, 1.18 ± 0.21 cm, 7.36 ± 3.07 and 1.63 ± 0.30 cm, 1.02 ± 0.28 cm, 1.32 ± 0.24 cm, 10.24 ± 4.79 respectively. Whereas, the pre- and post-operative ADH, PDH, MDH, and SL of Open-TLIF group were 1.61 ± 0.40 cm, 0.77 ± 0.21 cm, 1.19 ± 0.24 cm, 9.05 ± 5.48 and 1.81 ± 0.33 cm, 0.98 ± 0.24 cm, 1.39 ± 0.24 cm, 12.34 ± 4,74 respectively. MIS- and Open-TLIF group showed no significant differences in low back VAS, leg VAS, and ODI both in pre-operation and post-operation (P > 0.05). The estimated blood loss and hospital stay length in the MIS-TLIF group were significantly lower than those in the Open-TLIF group (P < 0.05).

Conclusion

MIS- and Open-TLIF provided similar clinical outcomes as the respect of low back VAS, leg VAS, and ODI. MIS-TLIF significantly reduced the blood loss and length of hospital stay though. The intervertebral parameters of DH and SL were both increased significantly, Open-TLIF group presented better sagittal balance in term of ADH and SL variables. The contrast investigation of intersegmental parameters may help the surgeons to figure out the further advantages of MIS-TLIF technique, and then better manage the rehabilitation and prevent the reoperation.

A Review of Techniques, Time Demand, Radiation Exposure, and Outcomes of Skin-anchored Intraoperative 3D Navigation in Minimally Invasive Lumbar Spinal Surgery

STUDY DESIGN

Retrospective cohort.

OBJECTIVE

To describe our technique for and evaluate the time demand, radiation exposure and outcomes of skin-anchored intraoperative three-dimensional navigation (ION) in minimally invasive (MIS) lumbar surgery, and to compare these parameters to 2D fluoroscopy for MI-TLIF.

SUMMARY OF BACKGROUND DATA

Limited visualization of anatomic landmarks and narrow access corridor in MIS procedures result in greater reliance on image guidance. Although two-dimensional fluoroscopy has historically been used, ION is gaining traction.

METHODS

Patients who underwent MIS lumbar microdiscectomy, laminectomy, or MI-TLIF using skin-anchored ION and MI-TLIF by the same surgeon using 2D fluoroscopy were selected. Operative variables, radiation exposure, and short-term outcomes of all procedures were summarized. Time-demand and radiation exposure of fluoroscopy and ION for MI-TLIF were compared.

RESULTS

Of the 326 patients included, 232 were in the ION cohort (92 microdiscectomies, 65 laminectomies, and 75 MI-TLIFs) and 94 in the MI-TLIF using 2D fluoroscopy cohort. Time for ION setup and image acquisition was a median of 22 to 24 minutes. Total fluoroscopy time was a median of 10 seconds for microdiscectomy, 9 for laminectomy, and 26 for MI-TLIF. Radiation dose was a median of 15.2 mGy for microdiscectomy, 16.6 for laminectomy, and 44.6 for MI-TLIF, of this, 93%, 95%, and 37% for microdiscectomy, laminectomy, and MI-TLIF, respectively were for ION image acquisition, with the rest attributable to the procedure. There were no wrong-level surgeries. Compared with fluoroscopy, ION for MI-TLIF resulted in lower operative times (92 vs. 108 min, P < 0.0001), fluoroscopy time (26 vs. 144 s, P < 0.0001), and radiation dose (44.6 vs. 63.1 mGy, P = 0.002), with equivalent time-demand and length of stay. ION lowered the radiation dose by 29% for patients and 55% for operating room personnel.

CONCLUSION

Skin-anchored ION does not increase time-demand compared with fluoroscopy, is feasible, safe and accurate, and results in low radiation exposure.

LEVEL OF EVIDENCE

3.

Image-Guided Navigation and Robotics in Spine Surgery

Image guidance (IG) and robotics systems are becoming more widespread in their utilization and can be invaluable intraoperative adjuncts during spine surgery. Both are highly reliant upon stereotaxy and either pre- or intraoperative radiographic imaging. While user-operated IG systems have been commercially available longer and subsequently are more widely utilized across centers, robotics systems provide unique theoretical advantages over freehand and IG techniques for placing instrumentation within the spine. While there is a growing plethora of data showing that IG and robotic systems decrease the incidence of malpositioned screws, less is known about their impact on clinical outcomes. Both robotics and IG may be of particular value in cases of substantial deformity or complex anatomy. Indications for the use of these systems continue to expand with an increasing body of literature justifying their use in not only guiding thoracolumbar pedicle screw placement, but also in cases of cervical and pelvic instrumentation as well as spinal tumor resection. Both techniques also offer the potential benefit of reducing occupational exposures to ionizing radiation for the operating room staff, the surgeon, and the patient. As the use of IG and robotics in spine surgery continues to expand, these systems' value in improving surgical accuracy and clinical outcomes must be weighed against concerns over cost and workflow. As newer systems incorporating both real-time IG and robotics become more utilized, further research is necessary to better elucidate situations where these systems may be particularly beneficial in spine surgery.

Evolving Navigation, Robotics, and Augmented Reality in Minimally Invasive Spine Surgery

Innovative technology and techniques have revolutionized minimally invasive spine surgery (MIS) within the past decade. The introduction of navigation and image-guided surgery has greatly affected spinal surgery and will continue to make surgery safer and more efficient. Eventually, it is conceivable that fluoroscopy will be completely replaced with image guidance. These advancements, among others such as robotics and virtual and augmented reality technology, will continue to drive the value of 3-dimensional navigation in MIS. In this review, we cover pertinent features of navigation in MIS and explore their evolution over time. Moreover, we aim to discuss the key features germane to surgical advancement, including technique and technology development, accuracy, overall health care costs, operating room time efficiency, and radiation exposure.

Defining the MIS-TLIF: A Systematic Review of Techniques and Technologies Used by Surgeons Worldwide

STUDY DESIGN

Systematic review.

OBJECTIVE

To date there is no consensus among surgeons as to what defines an MIS-TLIF (transforaminal lumbar interbody fusion using minimally invasive spine surgery) compared to an open or mini-open TLIF. This systematic review aimed to examine the MIS-TLIF techniques reported in the recent body of literature to help provide a definition of what constitutes the MIS-TLIF, based on the consensus of the majority of surgeons.

METHODS

We created a database of articles published about MIS-TLIF between 2010 and 2018. We evaluated the technical components of the MIS-TLIF including instruments and incisions used as well the order in which key steps are performed.

RESULTS

We could identify several patterns for MIS-TLIF performance that seemed agreed upon by the majority of MIS surgeons: use of paramedian incisions; use of a tubular retractor to perform a total facetectomy, decompression, and interbody cage implantation; and percutaneous insertion of the pedicle-screw rod constructs with intraoperative imaging.

CONCLUSION

Based on this review of the literature, the key features used by surgeons performing MIS TLIF include the use of nonexpandable or expandable tubular retractors, a paramedian or lateral incision, and the use of a microscope or endoscope for visualization. Approaches using expandable nontubular retractors, those that require extensive subperiosteal dissection from the midline laterally, or specular-based retractors with wide pedicle to pedicle exposure are far less likely to be promoted as an MIS-based approach. A definition is necessary to improve the communication among spine surgeons in research as well as patient education.

Accuracy of K-Wireless Insertion of Percutaneous Pedicle Screws Using Computer-Assisted Spinal Navigation: A Systematic Review and Single-Center Experience

OBJECTIVE

This study sought to 1) describe the use K-wireless pedicle screw insertion among adults (age ≥18 years) undergoing a minimally invasive fusion and 2) perform a systematic review (SR) of all studies that describe a navigated, K-wireless technique with 3-dimensional fluoroscopy.

METHODS

Patients undergoing a minimally invasive fusion requiring pedicle screw fixation for any indication were prospectively enrolled in the observational component of this study. An assessment of pedicle breach was performed independently and in duplicate based on a modification of the Belmont grading scale. Articles for the SR were identified from a structured search of Medline from inception to May 8, 2019, without restriction of language.

RESULTS

A total of 82 pedicle screws were placed in 20 patients who underwent surgery between January and June 2014. There was no significant difference in mean operative time between the cases included in this study and a matched cohort of 20 patients undergoing surgery with 2-dimensional fluoroscopy and K-wire-assisted pedicle screw placement (95 ± 13 vs. 87 ± 20 minutes, respectively; P > 0.05). There were 2 major pedicle breaches (Belmont grade 3) in a single patient, yielding a major breach rate of 2.44%. A total of 6 papers that described the placement of 700 pedicle screws in 160 patients between May 2011 and March 2017 were included in the SR. The overall breach rate was 7.00% (n = 37).

CONCLUSIONS

Percutaneous pedicle screws can be placed accurately and safely using 3-dimensional navigation without the use of K-wires and may confer benefits to patients and clinicians by reducing K-wire-associated complications and radiation exposure.

Retrospective Review of Immediate Restoration of Lordosis in Single-Level Minimally Invasive Transforaminal Lumbar Interbody Fusion: A Comparison of Static and Expandable Interbody Cages

BACKGROUND

Sagittal alignment is an important consideration in spine surgery. The literature is conflicted regarding the effect of minimally invasive transforaminal lumbar interbody fusion (MI-TLIF) on sagittal parameters and the role of expandable cage technology.

OBJECTIVE

To compare lordosis generated by static and expandable cages and to determine what factors affect postoperative sagittal parameters.

METHODS

Preoperative regional lordosis (RL), segmental lordosis (SL), and posterior disc height (PDH) were compared to postoperative values in single-level MI-TLIF performed using expandable or static cages. Patients were stratified based on preoperative SL: low lordosis (&lt;15 degrees), moderate lordosis (15-25 degrees), and high lordosis (&gt;25 degrees). Regression analyses were conducted to determine factors associated with postoperative SL and PDH.

RESULTS

Of the 171 patients included, 111 were in the static and 60 in the expandable cohorts. Patients with low preoperative lordosis experienced an increase in SL and maintained RL regardless of cage type. Those with moderate to high preoperative lordosis experienced a decrease in SL and RL with the static cage, but maintained SL and RL with the expandable cage. Although both cohorts showed an increase in PDH, the increase in the expandable cohort was greater. Preoperative SL was predictive of postoperative SL; preoperative SL, preoperative PDH, and cage type were predictive of postoperative PDH.

CONCLUSION

Expandable cages showed favorable results in restoring disc height and maintaining lordosis in the immediate postoperative period. Preoperative SL was the most significant predictor of postoperative SL. Thus, preoperative radiographic parameters and goals of surgery should be important considerations in surgical planning.

Evaluation of surgeon and patient radiation exposure by imaging technology in patients undergoing thoracolumbar fusion: systematic review of the literature

BACKGROUND CONTEXT

Minimally invasive spine techniques are becoming increasingly popular owing to their ability to reduce operative morbidity and recovery times. The downside to these new procedures is their need for intraoperative radiation guidance.

PURPOSE

To establish which technologies provide the lowest radiation exposure to both patient and surgeon.

STUDY DESIGN/SETTING

Systematic review OUTCOME MEASURES: Average intraoperative radiation exposure (in mSv per screw placed) to surgeon and patient. Average fluoroscopy time per screw placed.

METHODS

We reviewed the available English medical literature to identify all articles reporting patient and/or surgeon radiation exposure in patients undergoing image-guided thoracolumbar instrumentation. Quantitative meta-analysis was performed for studies providing radiation exposure or fluoroscopy use per screw placed to determine which navigation modality was associated with the lowest intraoperative radiation exposure. Values on meta-analysis were reported as mean ± standard deviation.

RESULTS

We identified 4956 unique articles, of which 85 met inclusion/exclusion criteria. Forty-one articles were included in the meta-analysis. Patient radiation exposure per screw placed for each modality was: conventional fluoroscopy without navigation (0.26±0.38 mSv), conventional fluoroscopy with pre-operative CT-based navigation (0.027±0.010 mSv), intraoperative CT-based navigation (1.20±0.91 mSv), and robot-assisted instrumentation (0.04±0.30 mSv). Values for fluoroscopy used per screw were: conventional fluoroscopy without navigation (11.1±9.0 seconds), conventional fluoroscopy with navigation (7.20±3.93 s), 3D fluoroscopy (16.2±9.6 s), intraoperative CT-based navigation (19.96±17.09 s), and robot-assistance (20.07±17.22 s). Surgeon dose per screw: conventional fluoroscopy without navigation (6.0±7.9 × 10^-3 mSv), conventional fluoroscopy with navigation (1.8±2.5 × 10^-3 mSv), 3D Fluoroscopy (0.3±1.9 × 10^-3 mSv), intraoperative CT-based navigation (0±0 mSv), and robot-assisted instrumentation (2.0±4.0 × 10^-3 mSv).

CONCLUSION

All image guidance modalities are associated with surgeon radiation exposures well below current safety limits. Intraoperative CT-based (iCT) navigation produces the lowest radiation exposure to surgeon albeit at the cost of increased radiation exposure to the patient relative to conventional fluoroscopy-based methods.

[Navigation in lumbar spinal surgery: When is it useful?]

BACKGROUND

Spinal navigation has evolved greatly since its implementation in the mid-1990s and is now widely used in lumbar spine surgery. However, navigation is not yet accepted as a standard technique.

APPLICATIONS

In addition to the classic use in lumbar pedicle screw instrumentation, navigation technology, especially in combination with intraoperative 3D imaging, can be applied in a wide range of indications and in all lumbar approaches. The technology is particularly helpful in minimally invasive operations. The concept of "total navigation" stands for an efficient use of the technique from skin incision on and aims at complete elimination of radiation exposure for the surgical team.

ADVANTAGES AND PITFALLS

High accuracy and low radiation exposure of the OR team are indisputable advantages of navigated operations, while time savings and economic benefits are yet to be demonstrated. Regular use and standardized workflow are essential for the safe and effective application of lumbar navigation. Currently, lumbar navigation technology is already of great importance, yet the complex technology requires intensive training. With improved user comfort and image quality, spinal navigation will continue to spread in the future.

"One and a half" minimally invasive transforaminal lumbar interbody fusion: single level transforaminal lumbar interbody fusion with adjacent segment unilateral laminotomy for bilateral decompression for spondylolisthesis with bisegmental stenosis

Symptomatic lumbar spondylolisthesis is commonly accompanied by spinal stenosis in multiple segments. These pathologies are routinely treated by multilevel decompression and instrumented fusion. However, it was hypothesized that a minimally invasive surgery (MIS) fusion in the unstable segment combined with a unilateral laminotomy for bilateral decompression (ULBD) in the adjacent stenotic segment is a biomechanically feasible alternative to a two-level fusion and superior to open laminectomy adjacent to a fused segment. This concept has demonstrated success in a recently published biomechanical cadaver study performed by our group. The present article offers a detailed step by step technical description for an MIS-TLIF (transforaminal lumbar interbody fusion) with adjacent ULBD.

Optimizing Patient Access During an Emergency While Using Intraoperative Computed Tomography

BACKGROUND

As minimally invasive spine surgery evolves, spine surgeons increasingly rely on advanced intraoperative computed tomography (iCT). iCT provides rapid acquisition of high-resolution images, reduces radiation exposure, improves surgical accuracy, and decreases operative time. However, all iCT systems currently available pose a patient safety risk as their physical space requirements limit patient access in the event of an emergency, particularly when patients are in the prone position. After a near-cardiac arrest at our institution during posterior cervical spine surgery, it was apparent that the presence of the iCT complicated the ability to rapidly reposition the patient in order to provide appropriate resuscitation.

METHODS

To ensure our ability to provide timely care during an emergency, we determined that a process which included all members of the operating room (OR) team was required. We held an initial planning meeting where a detailed plan-of-action was created, reviewed, and revised in response to feedback from all stakeholders. We then simulated a cardiac arrest to test our resuscitation plan with all members of the neurosurgery team. A mannequin was positioned prone on an OR table within the iCT, and a resuscitation plan was created.

RESULTS

The team orchestrated the mock resuscitation, and the time of cardiac arrest in the prone position to supine repositioning required 110 seconds. The simulation was recorded for post-"code" performance review. Application of the protocol during an actual cardiac arrest was associated with successful restoration of spontaneous circulation and full recovery.

CONCLUSIONS

The development and rehearsal of an emergency plan of action greatly facilitated the timely responsiveness of the neurosurgical OR team during a simulated cardiac arrest and was an effective way to identify and address key logistical issues regarding the use of an iCT system.

Intraoperative computed tomography as reliable navigation registration device in 200 cranial procedures

BACKGROUND

Registration accuracy is a main factor influencing overall navigation accuracy. Standard fiducial- or landmark-based patient registration is user dependent and error-prone. Intraoperative imaging offers the possibility for user-independent patient registration. The aim of this paper is to evaluate our initial experience applying intraoperative computed tomography (CT) for navigation registration in cranial neurosurgery, with a special focus on registration accuracy and effective radiation dose.

METHODS

A total of 200 patients (141 craniotomy, 19 transsphenoidal, and 40 stereotactic burr hole procedures) were investigated by intraoperative CT applying a 32-slice movable CT scanner, which was used for automatic navigation registration. Registration accuracy was measured by at least three skin fiducials that were not part of the registration process.

RESULTS

Automatic registration resulted in high registration accuracy (mean registration error: 0.93 ± 0.41 mm). Implementation of low-dose scanning protocols did not impede registration accuracy (registration error applying the full dose head protocol: 0.87 ± 0.36 mm vs. the low dose sinus protocol 0.72 ± 0.43 mm) while a reduction of the effective radiation dose by a factor of 8 could be achieved (mean effective radiation dose head protocol: 2.73 mSv vs. sinus protocol: 0.34 mSv).

CONCLUSION

Intraoperative CT allows highly reliable navigation registration with low radiation exposure.

The Role of the RN Circulator in a Navigated Posterior Spinal Fusion: 1.3 www.aornjournal.org/content/cme

The RN circulator plays a vital role in preparing for a minimally invasive spinal fusion with navigation by confirming that the necessary equipment and stakeholders are available and ensuring that the amount of equipment and the number of people in the room do not compromise patient safety or the sterility of the surgical field. Patients who undergo minimally invasive spinal fusion experience less blood loss, shorter hospital stays, and reduced costs than those who undergo open spinal fusion procedures. The overall successful fusion rates and improvement in patient quality of life are equivalent between the two approaches. Using navigation during minimally invasive and open spinal fusion procedures decreases radiation exposure to the patient and surgical team and helps ensure a more accurate placement of pedicle screws compared with nonnavigated minimally invasive or open spinal fusions.

Feasibility and Accuracy of Thoracolumbar Minimally Invasive Pedicle Screw Placement With Augmented Reality Navigation Technology

STUDY DESIGN

Cadaveric laboratory study.

OBJECTIVE

To assess the feasibility and accuracy of minimally invasive thoracolumbar pedicle screw placement using augmented reality (AR) surgical navigation.

SUMMARY OF BACKGROUND DATA

Minimally invasive spine (MIS) surgery has increasingly become the method of choice for a wide variety of spine pathologies. Navigation technology based on AR has been shown to be feasible, accurate, and safe in open procedures. AR technology may also be used for MIS surgery.

METHODS

The AR surgical navigation was installed in a hybrid operating room (OR). The hybrid OR includes a surgical table, a motorized flat detector C-arm with intraoperative 2D/3D imaging capabilities, integrated optical cameras for AR navigation, and patient motion tracking using optical markers on the skin. Navigation and screw placement was without any x-ray guidance. Two neurosurgeons placed 66 Jamshidi needles (two cadavers) and 18 cannulated pedicle screws (one cadaver) in the thoracolumbar spine. Technical accuracy was evaluated by measuring the distance between the tip of the actual needle position and the corresponding planned path as well as the angles between the needle and the desired path. Time needed for navigation along the virtual planned path was measured. An independent reviewer assessed the postoperative scans for the pedicle screws' clinical accuracy.

RESULTS

Navigation time per insertion was 90 ± 53 seconds with an accuracy of 2.2 ± 1.3 mm. Accuracy was not dependent on operator. There was no correlation between navigation time and accuracy. The mean error angle between the Jamshidi needles and planned paths was 0.9° ± 0.8°. No screw was misplaced outside the pedicle. Two screws breached 2 to 4 mm yielding an overall accuracy of 89% (16/18).

CONCLUSION

MIS screw placement directed by AR with intraoperative 3D imaging in a hybrid OR is accurate and efficient, without any fluoroscopy or x-ray imaging during the procedure.

LEVEL OF EVIDENCE

N/A.

Advantages and Disadvantages of Multi-axis Intraoperative Angiography Unit for Percutaneous Pedicle Screw Placement in the Lumbar Spine

We analyzed clinical usefulness of the high resolution imaging system in a hybrid operation room (OR) for posterior lumbar interbody fusion. A total of 17 patients with lumbar spondylolisthesis between February 2014 and August 2016 were included. Multi-axis imaging system in a hybrid OR was used in 12 patients (hybrid OR group); the conventional C-arm fluoroscopy, in 5 patients (C-arm group). The time to confirm the first percutaneous pedicle screw (PPS) angle (hybrid OR, 80 vs C-arm, 249 s; P = 0.0026) and the second to the last PPS angle (77 vs 90 s; P = 0.040) were shorter in the hybrid OR group. Placement accuracy was higher in the hybrid OR group (88.0 vs 59.1%; P = 0.010). Irradiation dose was significantly lower in the C-arm group (462 vs 102 mGy; P = 0.0013). This study suggested that the accuracy of PPS placement and time to confirm the PPS angle are the advantages in a hybrid OR.

Total Navigation in Spine Surgery; A Concise Guide to Eliminate Fluoroscopy Using a Portable Intraoperative Computed Tomography 3-Dimensional Navigation System

BACKGROUND

Portable intraoperative computed tomography (iCT) with integrated 3-dimensional navigation (NAV) offers new opportunities for more precise navigation in spinal surgery, eliminates radiation exposure for the surgical team, and accelerates surgical workflows. We present the concept of "total navigation" using iCT NAV in spinal surgery. Therefore, we propose a step-by-step guideline demonstrating how total navigation can eliminate fluoroscopy with time-efficient workflows integrating iCT NAV into daily practice.

METHODS

A prospective study was conducted on collected data from patients undergoing iCT NAV-guided spine surgery. Number of scans, radiation exposure, and workflow of iCT NAV (e.g., instrumentation, cage placement, localization) were documented. Finally, the accuracy of pedicle screws and time for instrumentation were determined.

RESULTS

iCT NAV was successfully performed in 117 cases for various indications and in all regions of the spine. More than half (61%) of cases were performed in a minimally invasive manner. Navigation was used for skin incision, localization of index level, and verification of implant position. iCT NAV was used to evaluate neural decompression achieved in spinal fusion surgeries. Total navigation eliminates fluoroscopy in 75%, thus reducing staff radiation exposure entirely. The average times for iCT NAV setup and pedicle screw insertion were 12.1 and 3.1 minutes, respectively, achieving a pedicle screw accuracy of 99%.

CONCLUSIONS

Total navigation makes spine surgery safer and more accurate, and it enhances efficient and reproducible workflows. Fluoroscopy and radiation exposure for the surgical staff can be eliminated in the majority of cases.

MINIMALLY INVASIVE SPINE SURGERY IN THE NUEVO HOSPITAL CIVIL DE GUADALAJARA "DR. JUAN I. MENCHACA"

ABSTRACT Objective: To describe our experience on a case series treated with minimal invasive techniques in spine surgery, with short-term follow-up and identify complications. Methods: A prospective analysis was performed on 116 patients operated on by the same team from September 2015 to June 2016. Evaluating the short-term follow-up we registered the surgical time, bleeding, complications, hospital stay, pre- and postoperatively neurological status, as well as scales of disability and quality of life. Demographic and surgical procedure data were analyzed with SPSS version 20 program. Results: A total of 116 patients with a mean age of 49.7 + 15.7 (21-85 years) underwent surgery being 76 (65%) with lumbar conditions and 37 (32%) with cervical conditions. The most common procedures were tubular discectomies (31), tubular bilateral decompression (17), lumbar MI-TLIFs (7), and anterior cervical discectomy and fusion (35). The mean blood loss was 50.6 cc, the hospital stay was 1.7 day, pre- and postoperative pain VAS were 7.4 % and 2.3%, respectively, pre- and postoperative Oswestry (ODI) were 64.6% and 13.1%, respectively, pre- and postoperative SF-36 of 37.8% and 90.3%. There were no major complications, except for a surgical wound infection in diabetic patient and three incidental durotomies, one of these being a contained fistula, treated conservatively. Conclusions: The current tendency towards minimally invasive surgery has been justified on multiple studies in neoplastic and degenerative diseases, with the preservation of the structures that support the spine biomechanics. The benefits should not replace the primary objectives of surgery and its usefulness depends on the skills of the surgeon, pathology and the adequate selection of the techniques. We found that the tubular access allows developing techniques such as discectomy, corpectomy and fusion without limiting exposure, avoiding manipulation of adjacent structures, reducing complications and being feasible in a public hospital.