Intraoperative 3-dimensional Navigation Research Articles

Technique for Validation of Intraoperative Navigation in Minimally Invasive Spine Surgery.

Intraoperative 3-dimensional navigation is an enabling technology that has quickly become a commonplace in minimally invasive spine surgery (MISS). It provides a useful adjunct for percutaneous pedicle screw fixation. Although navigation is associated with many benefits, including improvement in overall screw accuracy, navigation errors can lead to misplaced instrumentation and potential complications or revision surgery. It is difficult to confirm navigation accuracy without a distant reference point. To describe a simple technique for validating navigation accuracy in the operating room during MISS. The operating room is set up in a standard fashion for MISS with intraoperative cross-sectional imaging available. A 16-gauge needle is placed within the bone of the spinous process before intraoperative cross-sectional imaging. The entry level is chosen such that the space between the reference array and the needle encompasses the surgical construct. Before placing each pedicle screw, accuracy is verified by placing the navigation probe over the needle. This technique has identified navigation inaccuracy and led to repeat cross-sectional imaging. No screws have been misplaced in the senior author's cases since adopting this technique, and there have been no complications attributable to the technique. Navigation inaccuracy is an inherent risk in MISS, but the described technique may mitigate this risk by providing a stable reference point.

Is the Use of Intraoperative 3D Navigation for Thoracolumbar Spine Surgery a Risk Factor for Post-Operative Infection?

Pedicle screw fixation is a technique used to provide rigid fixation in thoracolumbar spine surgery. Safe intraosseous placement of pedicle screws is necessary to provide optimal fixation as well as to avoid damage to adjacent anatomic structures. Despite the wide variety of techniques available, none thus far has been able to fully eliminate the risk of malpositioned screws. Intraoperative 3-dimensional navigation (I3DN) was developed to improve accuracy in the placement of pedicle screws. To our knowledge, no previous studies have investigated whether infection rates are higher with I3DN. A single-institution, retrospective study of patients age > 18 undergoing thoracolumbar fusion and instrumentation was carried out and use of I3DN was recorded. The I3DN group had a significantly greater rate of return to the operating room for culture-positive incision and drainage (17 (4.1%) vs. 1 (0.6%), p = 0.025). In multivariate analysis, the use of I3DM did not reach significance with an OR of 6.49 (0.84–50.02, p = 0.073). Post-operative infections are multifactorial and potential infection risks associated with I3DN need to be weighed against the safety benefits of improved accuracy of pedicle screw positioning.

Intraoperative image guidance for lateral position surgery.

Recent advances in minimally invasive spine surgery techniques have precipitated the popularity of lateral position spine surgery, such as lateral lumbar interbody fusion (LLIF) and oblique lumbar interbody fusion (OLIF). Lateral position surgery offers a unique, minimally invasive approach to the lumbar spine that allows for preservation of anterior and posterior spinal elements. Traditionally, surgeons have relied upon fluoroscopy for triangulation and implant placement. Over the last decade, intraoperative 3-dimensional navigation (ION) has risen to the forefront of innovation in LLIF and OLIF. This technology utilizes intra-operative advanced imaging, such as comminuted tomography (CT), to map the patient’s 3D anatomy and allows the surgeon to accurately visualize instruments and implants in spatial relationship to the patient’s anatomy in real time. ION has the potential to improve accuracy during instrumentation, decrease operating room times, lower radiation exposure to the surgeon and staff, and increase feasibility of single-position surgery during which the spine is instrumented both laterally and posteriorly while the patient remains in the lateral decubitus position. Despite the advantages of ION, the intra-operative radiation exposure risk to patients is controversial. Future directions include continued innovation in ultra low radiation imaging (ULRI) techniques and image enhancement technology and in uses of robot-assisted navigation in single-position spine surgery.

Narrative review of intraoperative image guidance for transforaminal lumbar interbody fusion.

Recent advancements in imaging technology have changed the landscape of transforaminal lumbar interbody fusion (TLIF) with the objective of improving safety and efficacy for the patient and surgical team. Spine surgery, and specifically TLIFs, involve challenging anatomy and command precise surgical accuracy, creating an essential role for intraoperative imaging, navigation, and robotics. Traditionally, surgeons have relied upon fluoroscopy for pedicle screw and interbody placement. More recently, intraoperative 3-dimensional navigation (ION) has risen in popularity in TLIF surgery. This technology utilizes intra-operative advanced imaging, such as computed tomography (CT) and 3D-fluroscopy, to accurately track instruments and implants in relation to the patient’s anatomy. ION has demonstrated improved accuracy of pedicle screw placement, decreased operating room times, and lower radiation exposure to the surgeon and staff. However, conventional fluoroscopy, 3D fluoroscopy, intraoperative CT, image-guided navigation, and robot-assisted surgery all have a role in TLIF surgery. Numerous studies have been published regarding the benefits and pitfalls of these intraoperative tools in spine surgery, but there is a relative lack of research regarding some of the newer technologies surrounding TLIF. As future studies are published, and technology continues to evolve, surgeons must stay abreast of novel techniques to maximize patient safety and outcomes. Over the coming decade, we can expect intraoperative navigation and robotics to play a more significant role in spine surgery.

P104. A review of time demand, radiation exposure and outcomes of skin-anchored intraoperative 3D navigation in minimally invasive posterior cervical laminoforaminotomy

BACKGROUND CONTEXT Real time image-guidance and intra-operative 3-dimensional navigation (ION) are increasingly being utilized in spine surgery to provide better visualization, improve accuracy and enable less invasive procedures. Studies have shown effective early adaption and radiation reduction with this technology in minimally invasive lumbar spine surgery. However, the novel use of a noninvasive skin-anchored tracker has not yet been described for cervical spine surgery. PURPOSE To describe the time demand, radiation exposure and outcomes of ION using a skin-anchored tracker in minimally invasive posterior cervical laminoforaminotomy (MI-PCLF). STUDY DESIGN/SETTING Retrospective cohort study. PATIENT SAMPLE All patients who underwent MI-PCLF by a single surgeon from April17-November 19. OUTCOME MEASURES Time for navigation set-up, operative time, estimated blood loss (EBL), radiation exposure to operating room (OR) personnel and the patient, complications and length of stay. METHODS Operative variables, radiation exposure and perioperative outcomes were summarized using descriptive statistics. RESULTS Twenty-one patients (36Levels) with a mean age of 55+11.79yrs, BMI of 27.36+2.95kg/m2, and comprising 17(81%) males were included. A majority of cases were 1-level (9; 42.9%) or 2-level (10; 47.6%), with only one 3-level and one 4-level surgery. The operative levels were: C3C4 (11.1%), C4C5 (19.4%), C5C6 (22.2%), C6C7 (25%), C7T1 (22.2%). Time required for ION set-up, measured as the time from end of anesthesia induction to the start of the surgical procedure was a median of 34 mins [IQR 30-37]. This accounts for the time required for patient positioning, preparing and draping the incision site, placing the skin-anchored navigation tracker and acquiring a 3D image for real-time navigation. The total fluoroscopy time was a median of 10 sec [IQR 9-11], almost entirely attributable to ION image-acquisition; and radiation dose was a median of 2.5mGy [IQR 1.8-4.9]. Thus, radiation exposure to the patient was minimal. Since all OR personnel are behind a protective lead shield during ION image-acquisition, radiation exposure to the surgeon and OR team was negligible. One patient required a repeat ION spin, resulting in the fluoroscopy time for ION image-capture being 20sec. In two patients, ION was abandoned and the procedure was completed using fluoroscopy resulting in the total fluoroscopy time being 17&27sec (9sec for ION spin; rest for fluoroscopic guidance). Additionally, one patient had a radiation dose of 13.9mGy, which is almost three times the 75th percentile dose. Although the exact reason could not be determined, this may be attributable to a number of factors including deliberate or inadvertent higher dose settings, difference in C-arm position, calibration error, etc. Operative time was 62 mins [IQR 53-74] and EBL was low (25ml [IQR 25-25]. There were no wrong level surgeries, or any intra or post-operative complications. Median post-operative length of stay was 6hrs [IQR 4.4-20.9], with a majority (66.7%) of patients being discharged on the day of surgery. CONCLUSIONS The results of our study suggest that the use of intraoperative navigation using a skin-anchored tracker for posterior cervical laminoforaminotomy is a feasible, safe and accurate technique, resulting in short operative times and minimal complications. Further, it results in negligible radiation exposure to the OR team and low radiation exposure to the patient. FDA DEVICE/DRUG STATUS This abstract does not discuss or include any applicable devices or drugs.

Posterior Endoscopic Cervical Decompression: Review and Technical Note.

Endoscopic spine surgery for the treatment of degenerative spinal diseases from lumbar to cervical spine has accelerated over the past 2 decades. Posterior endoscopic cervical discectomy (PECD) has been described as a safe, effective, and minimally invasive procedure for cervical radiculopathy or even part of the myelopathy. This procedure also has been validated with comparable outcomes to open and microscopic surgery. Radiculopathy due to foraminal disc herniation or foraminal stenosis should be the optimum indications of this procedure. Intraoperative 3-dimensional navigation can help surgeons to get quick and great quality guidance for endoscopic surgeons. In this review, we will focus on the technical details and evidence-based results of PECD which is a promising procedure for cervical radiculopathy with the advantages of a minimally invasive method.

Prospective Evaluation of the Time Required for Insertion of 380 Lumbar and Sacral Pedicle Screws Using Navigation with an Intraoperative 3-Dimensional Imaging System

The aim of this study was to evaluate the time required for various parts of the procedure to insert lumbar and sacral pedicle screws using navigation with an intraoperative, 3-dimensional imaging system. Comparison of these timings was carried out for different surgical indications. This was a single-surgeon prospective cohort study of 69 consecutive patients (between August 2013 and June 2018) who underwent insertion of 380 pedicle screws into the lumbar and sacral vertebrae. Surgical indications, average time required for surgical exposure and attachment of the reference frame, average time required until completion of the first pedicle screw insertion, and average time required for insertion of a single pedicle screw were evaluated. The average time required from skin incision to reference frame attachment was 28.3 ± 20.4 (mean ± SD) minutes, and the average time required from reference frame attachment to completion of first pedicle screw insertion was 22.3 ± 9.6 minutes. The average time required for insertion of a single pedicle screw was 7.8 ± 2.7 minutes. When surgical indications were compared, the average time required for insertion of a single pedicle screw was 7.7 ± 2.6 minutes in surgery for spondylosis-related stenosis, 8.1 ± 2.8 minutes for degenerative scoliosis, and 8.2 ± 3.6 minutes for metastatic tumor (P = .89). There were no significant changes in these timings over consecutive 6-month periods. There is no significant learning curve and no significant difference in navigation setup and pedicle screw insertion timings with intraoperative 3-dimensional navigation systems for surgeries of different pathologies and levels of surgery. 2.

204. A review of time-demand, radiation exposure and outcomes of skin-anchored intraoperative 3D navigation in minimally invasive lumbar spinal surgery

BACKGROUND CONTEXT Real time image-guidance and intraoperative 3-dimensional navigation (ION), which utilize either a bone- or skin-anchored tracker, are increasingly being utilized in spine surgery to provide better visualization of abnormal anatomy, improve accuracy and enable less invasive procedures. However, ION is associated with considerable upfront costs, intraoperative time-demand and potentially greater radiation exposure. PURPOSE To describe the time demand, radiation exposure and outcomes of ION using a skin-anchored tracker in minimally invasive lumbar surgery. STUDY DESIGN/SETTING Retrospective cohort study. PATIENT SAMPLE All patients who underwent 1-level MIS microdiscectomy, laminectomy or TLIF by a single surgeon from April 2017 to January 2018. OUTCOME MEASURES Operative time, fluoroscopy time and radiation dose. METHODS Operative variables, radiation exposure and short-term outcomes of all three surgical procedures were summarized using descriptive statistics. RESULTS Of the 232 patients in this study, 92 underwent a microdiscectomy, 65 a laminectomy and 75 an MI-TLIF. All procedures were performed using a tubular retractor system, operating microscope and skin-anchored ION. Time required for ION set-up, measured as the time taken from completion of anesthesia induction to the start of the surgical procedure was a median of 22 minutes (IQR 19–25) for microdiscectomy, 23 (IQR 21–26) for laminectomy and 24 (IQR 21–28) for MI-TLIF. This accounts for the time required for patient positioning, preparing and draping the incision site, placing the skin-anchored navigation tracker and acquiring a 3D image for real-time navigation. The total fluoroscopy time was a median of 10 seconds (IQR 9–10) for microdiscectomy, 9 (IQR 9–10) for laminectomy and 26 (IQR 20–34) for MI-TLIF. Of this, an average of 9 seconds was required for image-acquisition for ION, while the remaining fluoroscopy time was for the surgical procedure (median 0, 0 and 17 seconds for microdiscectomy, laminectomy and MI-TLIF respectively). The total radiation dose was a median of 15.2mGy (IQR 8.6–23.9) for microdiscectomy, 16.6 (IQR 10.85–27.2) for laminectomy and 44.6 (IQR 35.6–64) for MI-TLIF. Of this, the median radiation dose required for image acquisition for ION was 93%, 95% and 37% of the total dose for microdiscectomy, laminectomy and MI-TLIF respectively, with the rest attributable to the surgical procedure. The operative time was a median of 42 minutes (IQR 35–54) for microdiscectomy, 50 (IQR 39–58) for laminectomy and 92 (IQR 77–101) for MI-TLIF. For all three procedures, median blood loss was 25 ml, the only reported intraoperative complication was durotomy, occurring in 1 patient undergoing laminectomy, and the most common in-hospital complication was urinary retention requiring catheterization, seen 0%, 3.1% and 6.7% of microdiscectomies, laminectomies and MI-TLIFs respectively. There were no wrong-level surgeries in any patients. CONCLUSIONS The use of intraoperative navigation using a skin-anchored navigation tracker is a feasible, safe and accurate approach. For decompression surgeries, a majority of the radiation dose and fluoroscopy time is attributable to image-acquisition for ION. In contrast, image-acquisition accounts for FDA DEVICE/DRUG STATUS This abstract does not discuss or include any applicable devices or drugs.

P38. Intraoperative 3D navigation versus fluoroscopy: a comparison of time-demand, radiation exposure and outcomes in minimally invasive transforaminal lumbar interbody fusion (MI-TLIF)

BACKGROUND CONTEXT Real time image-guidance and intra-operative 3-dimensional navigation (ION), which utilize either a bone- or skin-anchored tracker, are increasingly being utilized in spine surgery to provide better visualization of abnormal anatomy, improve accuracy and enable less invasive procedures. However, ION is also associated with considerable upfront costs, intra-operative time-demand and potentially greater radiation exposure. PURPOSE To compare the time demand, radiation exposure and outcomes of 3D ION using a skin-anchored tracker (Stryker SpineMap 3D Navigation System, Stryker SpineMask Tracker) and conventional 2D fluoroscopy in Minimally Invasive Transforaminal Lumbar Interbody Fusion (MI-TLIF). STUDY DESIGN/SETTING Retrospective cohort study. PATIENT SAMPLE All patients who underwent single-level MI-TLIF by a single surgeon between 2011 and 2018. OUTCOME MEASURES Operative time, fluoroscopy time and radiation dose. METHODS Demographics, operative factors and radiation exposure were compared using chi square test for categorical, and independent sample t-test and median t-test for normally and non-normally distributed continuous variables, respectively. RESULTS Of the 169 patients in this study, 94 underwent MI-TLIF using fluoroscopy and 75 using skin-based ION. There were no significant differences in demographics (age:p=0.632; sex:p=0.877, BMI:p=0.732) or level of surgery (p=0.614), with L4-L5 being the most common level in both cohorts. The time required for ION set-up, measured as the time taken from completion of anesthesia induction to the start of the surgical procedure was a median of 24 minutes [IQR 21–28]. This accounts for the time required for patient positioning, preparing and draping the incision site, placing the skin-anchored navigation tracker and acquiring a three-dimensional image for real-time navigation. The use of ION resulted in significantly shorter operative times (median 92 minutes [IQR 77–101] vs 108 [IQR 95–124.5] for fluoroscopy, p CONCLUSIONS The results of our study show that the use of intra-operative navigation using a skin-anchored navigation tracker is a feasible, safe and accurate approach that does not increase the total time-demand of the surgery. In addition, intra-operative navigation was advantageous in terms of shorter operative times, reduced fluoroscopy time and lower total radiation exposure compared to traditional fluoroscopy. FDA DEVICE/DRUG STATUS Stryker SpineMap 3D Navigation System, Stryker SpineMask Tracker (Approved for this indication)

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

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. To validate the utility and accuracy of OTI in the cervical spine. This is a prospective preclinical cadaveric and clinical cohort study. 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. 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. 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.

Evaluation of Correction of Radiologic Parameters (Angulation and Displacement) and Accuracy of C2 Pedicle Screw Placement in Unstable Hangman's Fracture with Intraoperative Computed Tomography-Based Navigation.

Opinions vary regarding optimal treatment of unstable hangman's fractures, including rigid orthosis and internal fixation. The anatomy of upper cervical spine is complex. The advent of intraoperative 3-dimensional navigation systems facilitates safe and accurateinstrumentation. To evaluate radiologic parameters of fracture morphology in unstable hangman's fracture in preoperative and postoperative period and accuracy of inserting axis pedicle screws by using intraoperative computed tomography-based navigation. Fifteen patients with unstable hangman's fractures with age ranging from 17 years to 81 years were operated using computed tomography-based navigation from September 2011 to march 2016. Patient's age, sex, mechanism of injury, associated injuries, and neurologic status were noted. Clinical outcome, accuracy of screw insertion, preoperative and postoperative displacement, and angulation of C2 over C3 and bony fusion were assessed. Overall, 76 screws were inserted including 30 screws in C2 pedicle with 2 (2/60; 6.7%) malplaced screws in C2 pedicle. Mean follow-up period was 34 ± 18 months (range 7-80 months). Mean hospital stay was 12.8 ± 2.4 days. Mean preoperative and postoperative displacements were 4.09 mm ± 1.78 mm and 1.82 mm ± 1.14 mm respectively with a mean reduction of 2.27 mm ± 1.49 mm. Mean preoperative angulation was 7.23° ± 11.96° and postoperative angulation was 2.32° ± 4.77° with a mean reduction of 5.11° ± 11.96°. Bony fusion was achieved and rotation was preserved at C1-C2 joint in all cases. Intraoperative O-arm-based navigation is a safe, accurate, and effective tool for screw placement in patients with unstable hangman fracture and achieves good anatomical reduction.

Computed tomography-guided C2 pedicle screw placement for treatment of unstable hangman fractures.

Case series and description of technique. The purpose of this study was to evaluate the feasibility and accuracy of inserting pedicle screws in unstable Hangman fracture cases by using intraoperative CT (O-arm) based navigation. Hangman fracture, also known as traumatic spondylolisthesis of the C2, is defined as a fracture involving the lamina, articular facets, pedicles, or pars of the axis vertebra. Opinions vary regarding the optimal treatment of unstable Hangman fractures. Some authors have recommended the use of rigid orthosis, whereas others have recommended surgical stabilization. The peculiar anatomy of the upper cervical spine is highly variable, and the presence of surrounding neurovascular structures makes pedicle screw fixation even more technically challenging. The advent of intraoperative 3-dimensional navigation systems permits safe and accurate instrumentation of the cervical spine. Ten patients with unstable Hangman fracture, with age ranging from 17 years to 81 years, were operated under O-arm-based navigation, and screw position was confirmed with intraoperative computed tomographic scan. A total of 52 screws were inserted under O-arm guidance: 20 in C2 pedicle, 20 in C3 lateral mass, and rest in C4 lateral mass. Screw misplacement was seen in only 1 C2 pedicle screw (1 of 20, 5%). No new-onset neurological deficit developed in any of the patients. Follow-up ranged from 3 months to 21 months. Bony fusion was achieved in all. Full rotation was preserved at C1-C2 joint. All the patients (50%) with neurological deficits before surgery improved after surgery. This series demonstrates that C2 pedicle screws can be put with precision under O-arm-guided navigation, and intraoperative computed tomographic scan can confirm position of screws. Patients can be operated and mobilized early with negligible risk of screw misplacement, with preservation of motion at the C1-C2 joint. 4.

Intraoperative 3-Dimensional Navigation and Ultrasonography During Posterior Decompression With Instrumented Fusion for Ossification of the Posterior Longitudinal Ligament in the Thoracic Spine

A retrospective clinical study was conducted. The purpose of this study was to describe the clinical outcomes of intraoperative 3D navigation (ITN) and ultrasonography during posterior decompression and instrumented fusion for thoracic myelopathy due to ossification of the posterior longitudinal ligament (OPLL). The symptoms caused by thoracic-ossification of the posterior longitudinal ligament (T-OPLL) are usually progressive and do not respond to conservative treatment-surgical intervention is the only effective treatment option. Various methods have been described for the treatment of symptomatic T-OPLL, all of which have limitations. The study included 18 patients with T-OPLL who underwent posterior decompression with instrumented fusion from 2006 to 2011. A staged operative procedure was used. First, pedicle screws were placed with ITN and a wide laminectomy was performed with resection of ossification of the ligamentum flavum (if present). With insufficient decompression on intraoperative ultrasonography, additional circumferential decompression was performed through a transpedicular approach. ITN-guided OPLL resection was performed using a burr attached to a navigational tracker. In all cases, posterior instrumented fusion was performed in situ. The outcomes were evaluated with the modified Japanese Orthopaedic Association scores and recovery rates. Intraoperative ultrasonography showed that posterior laminectomy was sufficient in 6 patients; the remaining 12 were treated with additional circumferential decompression. The follow-up period ranged from 1 to 6 years (mean period, 2.8 y). Postoperative transient neurological deterioration occurred in 1 patient, and cerebrospinal fluid leakage occurred in 4 patients. All patients showed neurological recovery with a mean Japanese Orthopaedic Association score that improved from 5.5 points preoperatively to 8.5 points at the final follow-up and a mean recovery rate of 54.5%. Intraoperative ultrasonography and ITN are safe and reliable imaging methods for posterior decompression and instrumented fusion for thoracic myelopathy caused by OPLL.

Occipital-C2 Transarticular Fixation for Occipitocervical Instability Associated With Occipitalization of the Atlas in Patients With Klippel-Feil Syndrome, Using Intraoperative 3-Dimensional Navigation System

Retrospective case series. The aim of this study was to describe the clinical outcomes of cervical reduction and occipital-C2 transarticular (OCTA) fixation with an assistance of intraoperative 3-dimensional navigation system (ITNS) during the treatment of reducible occipitocervical instability (OCI) in patients with Klippel-Feil syndrome (KFS) with occipitalization of the atlas and fusion of C2-C3. Patients with KFS have congenital fusions of at least 2 cervical segments and may gradually develop symptoms at the hypermobile articulations adjacent to the cervical synostosis. This is particularly common in patients with KFS with occipitalization of the atlas and C2-C3 fusion. These patients may be at risk for instability and neurological complications of the occipitocervical junction that require occipitocervical reconstruction and fusion. Numerous treatment techniques are available for this pathological condition. However, there has yet to be a study of reducible OCI, showing successful treatment with intraoperative reduction and posterior OCTA fixation using ITNS. From 2006 to 2011, 9 patients with KFS with reducible OCI attributed to occipitalization of the atlas and C2-C3 fusion were surgically treated. After a limited foramen magnum decompression, reduction of the OCI was conducted by intraoperative cervical traction and extension, followed by OCTA fixation using a direct posterior approach and with the assistance of ITNS. The follow-up period ranged from 6 to 60 months (mean, 31 mo). Good decompression and bone fusion were achieved in all the patients. The clinical symptoms had improved for all patients. There were no intraoperative or postoperative complications. In patients with KFS with occipitalization of the atlas and C2-C3 fusion, manual cervical traction in tandem with cervical extension, followed by posterior OCTA fixation and fusion provides a safe, effective treatment of OCI and ventral brainstem impingement. IFTN is a feasible tool for monitoring cervical reduction and OCTA screw insertion in patients with KFS with this pathological condition.

Three-Dimensional Navigation in Otorhinolaryngological Surgery with the Viewing Wand

We report our experiences with the ISG Viewing Wand intraoperative 3-dimensional navigation device in endonasal endoscopic procedures of the paranasal sinuses, anterior skull base, and petrous bone. In the last 12 months we have routinely used the wand in 90 patients for treatment of polyposis nasi, for biopsies and removal of tumors in the nasal cavity and at the frontal skull base, for endocrine ophthalmopathy, and in 1 case for cholesteatoma. We present our computed tomography, magnetic resonance imaging, and clinical protocols that allow a precise routine use of the Viewing Wand. In all cases, the system was extremely helpful for intraoperative localization and helped to optimize surgery.

Commentary 1

<h3>ABSTRACT</h3> <h3>Background</h3> The aim of this study was to evaluate the time required for various parts of the procedure to insert lumbar and sacral pedicle screws using navigation with an intraoperative, 3-dimensional imaging system. Comparison of these timings was carried out for different surgical indications. <h3>Methods</h3> This was a single-surgeon prospective cohort study of 69 consecutive patients (between August 2013 and June 2018) who underwent insertion of 380 pedicle screws into the lumbar and sacral vertebrae. Surgical indications, average time required for surgical exposure and attachment of the reference frame, average time required until completion of the first pedicle screw insertion, and average time required for insertion of a single pedicle screw were evaluated. <h3>Results</h3> The average time required from skin incision to reference frame attachment was 28.3 ± 20.4 (mean ± SD) minutes, and the average time required from reference frame attachment to completion of first pedicle screw insertion was 22.3 ± 9.6 minutes. The average time required for insertion of a single pedicle screw was 7.8 ± 2.7 minutes. When surgical indications were compared, the average time required for insertion of a single pedicle screw was 7.7 ± 2.6 minutes in surgery for spondylosis-related stenosis, 8.1 ± 2.8 minutes for degenerative scoliosis, and 8.2 ± 3.6 minutes for metastatic tumor (<i>P</i> = .89). There were no significant changes in these timings over consecutive 6-month periods. <h3>Conclusions</h3> There is no significant learning curve and no significant difference in navigation setup and pedicle screw insertion timings with intraoperative 3-dimensional navigation systems for surgeries of different pathologies and levels of surgery. <h3>Level of Evidence</h3> Level 2.