A prospective clinical study for pedicle screw placement with augmented reality surgical navigation including intraoperative 3D imaging in a hybrid operating room was performed in 20 patients of whom 13 had scoliosis. The screw placement accuracy was 94.1% with an average navigation time of 5.4 minutes per screw placement.

Study Design.A cadaveric laboratory study.Objective.The aim of this study was to assess the feasibility and accuracy of thoracic pedicle screw placement using augmented reality surgical navigation (ARSN).Summary of Background Data.Recent advances in spinal navigation have shown improved accuracy in lumbosacral pedicle screw placement but limited benefits in the thoracic spine. 3D intraoperative imaging and instrument navigation may allow improved accuracy in pedicle screw placement, without the use of x-ray fluoroscopy, and thus opens the route to image-guided minimally invasive therapy in the thoracic spine.Methods.ARSN encompasses a surgical table, a motorized flat detector C-arm with intraoperative 2D/3D capabilities, integrated optical cameras for augmented reality navigation, and noninvasive patient motion tracking. Two neurosurgeons placed 94 pedicle screws in the thoracic spine of four cadavers using ARSN on one side of the spine (47 screws) and free-hand technique on the contralateral side. X-ray fluoroscopy was not used for either technique. Four independent reviewers assessed the postoperative scans, using the Gertzbein grading. Morphometric measurements of the pedicles axial and sagittal widths and angles, as well as the vertebrae axial and sagittal rotations were performed to identify risk factors for breaches.Results.ARSN was feasible and superior to free-hand technique with respect to overall accuracy (85% vs. 64%, P < 0.05), specifically significant increases of perfectly placed screws (51% vs. 30%, P < 0.05) and reductions in breaches beyond 4 mm (2% vs. 25%, P < 0.05). All morphometric dimensions, except for vertebral body axial rotation, were risk factors for larger breaches when performed with the free-hand method.Conclusion.ARSN without fluoroscopy was feasible and demonstrated higher accuracy than free-hand technique for thoracic pedicle screw placement.Level of Evidence: N/A

Study Design. Cadaveric animal laboratory study. Objective. To evaluate the feasibility and accuracy of pedicle cannulation using an augmented reality surgical navigation (ARSN) system with automatic instrument tracking, yielding feedback of instrument position in relation to deep anatomy. Summary of Background Data. Minimally invasive spine surgery (MISS) has the possibility of reducing surgical exposure resulting in shorter hospital stays, lower blood loss and infection rates compared with open surgery but the drawback of limiting visual feedback to the surgeon regarding deep anatomy. MISS is mainly performed using image-guided 2D fluoroscopy, thus exposing the staff to ionizing radiation. Methods. A hybrid operating room (OR) equipped with a robotic C-arm with integrated optical cameras for augmented reality instrument navigation was used. In two pig cadavers, cone beam computed tomography (CBCT) scans were performed, a 3D model generated, and pedicle screw insertions were planned. Seventy-eight insertions were performed. Technical accuracy was assessed on post-insertion CBCTs by measuring the distance between the navigated device and the corresponding pre-planned path as well as the angular deviations. Drilling and hammering into the pedicle were also compared. Navigation time was measured. An independent reviewer assessed a simulated clinical accuracy according to Gertzbein. Results. The technical accuracy was 1.7 ± 1.0 mm at the bone entry point and 2.0 ± 1.3 mm at the device tip. The angular deviation was 1.7 ± 1.7° in the axial and 1.6 ± 1.2° in the sagittal plane. Navigation time per insertion was 195 ± 93 seconds. There was no difference in accuracy between hammering and drilling into the pedicle. The clinical accuracy was 97.4% to 100% depending on the screw size considered for placement. No ionizing radiation was used during navigation. Conclusion. ARSN with instrument tracking for MISS is feasible, accurate, and radiation-free during navigation. Level of Evidence: 3

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

BackgroundIntracranial hemorrhage (ICH) is a recognized complication of adults treated with extracorporeal membrane oxygenation (ECMO) and is associated with increased morbidity and mortality. However, the predictors of ICH in this patient category are poorly understood. The purpose of this study was to identify predictors of ICH in ECMO-treated adult patients.MethodsWe conducted a retrospective review of adult patients (≥18 years) treated with ECMO at the Karolinska University Hospital (Stockholm, Sweden) between September 2005 and June 2016, excluding patients with ICH upon admission or those who were treated with ECMO for less than 12 h. In a comparative analysis, the primary end-points were the difference in baseline characteristics and predictors of hemorrhage occurrence (ICH vs. non-ICH cohorts). The secondary end-point was difference in mortality between groups. Paired testing and uni- and multivariate regression models were applied.ResultsTwo hundred and fifty-three patients were included, of which 54 (21%) experienced an ICH during ECMO treatment. The mortality for patients with ICH was 81% at 1 month and 85% at 6 months, respectively, compared to 28 and 33% in patients who did not develop ICH. When comparing ICH vs. non-ICH cohorts, pre-admission antithrombotic therapy (p = 0.018), high pre-cannulation Sepsis-related Organ Failure Assessment (SOFA) coagulation score (p = 0.015), low platelet count (p < 0.001), and spontaneous extracranial hemorrhage (p = 0.045) were predictors of ICH. In a multivariate regression model predicting ICH, pre-admission antithrombotic therapy and low platelet count demonstrated independent risk association. When comparing the temporal trajectories for coagulation variables in the days leading up to the detection of an ICH, plasma antithrombin significantly increased per patient over time (p = 0.014). No other temporal trajectories were found.ConclusionsICH in adult ECMO patients is associated with a high mortality rate and independently associated with pre-admission antithrombotic therapy and low platelet count, thus highlighting important areas of potential treatment strategies to prevent ICH development.Electronic supplementary materialThe online version of this article (doi:10.1186/s40560-017-0223-2) contains supplementary material, which is available to authorized users.

Background: Intracranial hemorrhage (ICH) is a common complication in adults treated with extracorporeal membrane oxygenation (ECMO).Objectives: The aim of this study was to conduct a systematic review of the literature on the incidence, outcome and predictors of ECMO-associated ICH in adult patients, supplemented by a narrative review of its pathophysiology, management and future perspectives.Methods: MEDLINE, EMBASE, Cochrane Database of Systematic Reviews and www.clinicaltrials.gov were systematically searched. Studies that reported incidence, outcome or predictors of ECMO-associated ICH in adults (≥18 years) were eligible for inclusion.Results: Twenty five articles were included in the systematic review. The incidence of ECMO-associated ICH varied between 1.8 and 21 %. Mortality rates in ICH-cohorts varied between 32 and 100 %, with a relative risk of mortality of 1.27–4.43 compared to non-ICH cohorts. An increased risk of ICH was associated with ECMO-duration, antithrombotic therapy, altered intrinsic coagulation, renal failure, need of blood products, rapid hypercapnia at ECMO initiation, and even pre-ECMO morbidity.Conclusions: ICH is a common complication in adults treated with ECMO and associated with increased mortality. Treating an ICH during ECMO represents a balance between pro- and anticoagulatory demands. Neurosurgical treatment is associated with severe morbidity, but has been successful in selected cases. Future studies should aim at investigating the validity and feasibility of non-invasive monitoring in early detection of ECMO-associated ICH.

This study aimed to compare screw placement accuracy and clinical aspects between Augmented Reality Surgical Navigation (ARSN) and free-hand (FH) technique. Twenty patients underwent spine surgery with screw placement using ARSN and were matched retrospectively to a cohort of 20 FH technique cases for comparison. All ARSN and FH cases were performed by the same surgeon. Matching was based on clinical diagnosis and similar proportions of screws placed in the thoracic and lumbosacral vertebrae in both groups. Accuracy of screw placement was assessed on postoperative scans according to the Gertzbein scale and grades 0 and 1 were considered accurate. Procedure time, blood loss and length of hospital stay, were collected as secondary endpoints. A total of 262 and 288 screws were assessed in the ARSN and FH groups, respectively. The share of clinically accurate screws was significantly higher in the ARSN vs FH group (93.9% vs 89.6%, p < 0.05). The proportion of screws placed without a cortical breach was twice as high in the ARSN group compared to the FH group (63.4% vs 30.6%, p < 0.0001). No statistical difference was observed for the secondary endpoints between both groups. This matched-control study demonstrated that ARSN provided higher screw placement accuracy compared to free-hand.Compared to conventional free-hand (FH) surgical technique, computer-assisted navigation using intraoperative 3D imaging has been shown to improve screw placement accuracy and reduce complications due to screw misplacements 1 . Moreover, improved accuracy has also been shown in more challenging conditions, such as scoliosis surgery, where it may be of even greater importance 2 . Consequently, navigation also reduces the frequency of postoperative revision surgery compared to FH surgery 3 .Although several studies have compared intraoperative image guidance to free-hand (FH) technique, the evidence in favor of navigation is still limited. In a recent systematic review, Chan et al., found only four studies comparing computed tomography (CT) guidance with free-hand methods head-to-head, including one small (10 patients in each group, 169 screws in total) randomized study 4 . Overall, the reviewers found only moderate level evidence showing that CT guidance has lower breach rates than FH, while screw-related complication rates were conflicting at 0% in CT navigation compared with 0%-1.7% in FH groups 5 . In a more recent retrospective study comparing O-arm navigation to FH, Wang et al. demonstrated higher pedicle screw accuracy and lower total

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