Intraoperative 3D Navigation Research Articles

Accuracy of screw stabilization of the dorsal pelvic ring using a hybrid operating room: 5 Year experience in a level 1 trauma center

IntroductionAccuracy for screw placement in the dorsal pelvic ring can be enhanced using intraoperative 3D navigation. Advances in intraoperative imaging lead to benefits for pelvic surgery. New c-arms are equipped with flat panel detectors, which have a larger detector and assure higher image quality with accompanying dose reduction. A hybrid OR is defined by a fixed imaging system in an operating room providing the benefit of the surgical environment in combination with advanced intraoperative imaging. Aim of our investigation was to analyze the accuracy of navigated sacroiliac (SI) and transsacral transiliac (TSTI) screws in the dorsal pelvic ring, which were implanted with a hybrid OR in the first five years of use. Material and methodsAll percutaneous SI or TSTI screws implanted in the hybrid OR using intraoperative navigation in the first 5 years of utilization (between June 2012 to June 2017) were included. Intraoperative 3D-scans and postoperative computed tomography were examined for screw perforation. Results210 SI and TSTI screws were implanted in 187 patients using intraoperative navigation in the hybrid-OR. 90.6 % of SI screws showed no cortical perforation. 6,3 % had a grade 1, 2.4 % a grade 2 and 0.8 % a grade 3 perforation. In 80.7 % of TSTI screws no perforation and in 13.3 % a grade 1 perforation was detected. 3.6 % showed a grade 2 and 2.4 % a grade 3 perforation. No significant difference between both screw types regarding the grade of cortical perforation could be seen. No significant relation between perforation rate and year of operation could be detected. ConclusionIntraoperative navigation in a hybrid OR ensures a high accuracy for SI screws. Due to the large field of view and high image quality TSTI screws can be safely implanted in S1 and S2. Utilization of a hybrid-OR is accompanied with a steep learning curve.

Use of 3D Navigation Versus Traditional Fluoroscopy for Posterior Pelvic Ring Fixation.

Unstable pelvic ring disruption is most commonly treated with closed reduction and percutaneous screw fixation. Traditional methods involve screw placement under fluoroscopic imaging, but with recent technologic advances, intraoperative 3D navigation can now be used to help with the insertion of sacroiliac screws. Various cadaver studies have shown that placement of sacroiliac screws under 3D navigation is more accurate than placement under traditional fluoroscopic guidance. This retrospective review of 134 patients evaluated the clinical use of 3D navigation vs traditional fluoroscopy for sacroiliac screw insertion at an urban level I trauma center. Analysis of surgical data showed a significantly longer imaging time with the conventional method compared with the more experimental 3D navigation (204.06 seconds vs 66.90 seconds, P<.01). Further, a significantly larger radiation dose to both the patient and the staff was seen with traditional fluoroscopy (80.1 mGy for each) compared with that of 3D navigation (39.0 mGy and 25.1 mGy, respectively). No statistically significant difference was seen for outcome or follow-up variables between the 2 extrapolated groups. These variables included length of hospital stay, infection, nerve injury, and hardware breakage. The authors advocate that 3D navigated sacroiliac screws are safe and effective for pelvic ring stabilization; this method may be especially applicable in certain difficult imaging situations, such as morbid obesity, bowel gas interference, and overlapping pelvic structures that make the sacral corridor difficult to discern with traditional 2D fluoroscopy. Safe placement of transiliac-transsacral screws (P<.01) occurred with 3D navigation, and there was a statistically significant increase in adequate screw placement in multiple sacral segments compared with single-level stabilization (P<.01). [Orthopedics. 2021;44(4):229-234.].

The “STARS–CT-MADE” Study: Advanced Rehearsal and Intraoperative Navigation for Skull Base Tumors

Skull base meningiomas represent a challenge for neurosurgeons, and the procedures are typically performed by experienced neurosurgeons, thus limiting resident training. A new simulation and rehearsal device can be used as an aid for senior surgeons during these operations and serve as a training tool for junior surgeons. Forty patients harboring an anterior/middle fossa meningioma were recruited. Surgical Theater, a rehearsal/simulation platform, was used for preoperative planning and intraoperative 3D navigation on 20 patients (CT-MADE group), while the remaining (control group) underwent a traditional navigation. Qualitative comparisons between the 2 groups were made with regard to surgical procedure and patient outcome. Satisfaction questionnaires were completed by expert neurosurgeons and residents to assess the overall usefulness of the platform. Furthermore, the surface of the simulated craniotomy performed during the planning was compared with the one actually performed during surgery in order to evaluate the reliability of the planning. No differences between the 2 groups were found (surgery duration: P= 0.4; visual impairment: P=0.56). Both residents and senior neurosurgeons enjoyed using the platform for intraoperative navigation and planning; simulated craniotomies were significantly smaller as compared with the real ones (P= 0.009), probably because it was not intuitive to depict the exact margins of the operculum with the platform. Surgical Theater helped residents to improve their anatomic and procedural comprehension and was deemed as a useful aid to safely perform some demanding neurosurgical procedures, by both senior and junior surgeons.

3D Reconstruction and Augmented Reality Display of Bone Structure Based on Ultrasound Segmentation with Feature-Reweighted U-Net

<p indent=0mm>During the minimally invasive orthopedic surgery, surgeons insert surgical instruments under the guidance of two-dimensional (2D) X-ray images of bone structures that displayed on a screen. This method not only lacks of intuitive three-dimensional (3D) information, but also exposes patients and surgeons to significant amounts of ionizing radiations. To solve these problems, this paper proposes 3D reconstruction and augmented reality display of bone structure based on Free-hand ultrasound segmentation with feature-reweighted U-Net, and provides doctors with 3D bone structure for radiation-free surgical navigation. Firstly, a feature-reweighted U-Net is developed for accurate segmentation of bone surfaces from Free-hand ultrasound scans. Then, the segmented bone surfaces are reconstructed to acquire 3D bone structure according to the locations of ultrasound images. Finally, the bone structure is further rendered using integral photography techniques for augmented reality guidance. The experiments are finished on ultrasound data set of phantom and patients. The bone segmentation accuracy of (88.51±1.44)% and bone reconstruction error of <sc>(1.29±0.11) mm</sc> are acquired during the experiments. The proposed method can provide surgeons with intuitive intraoperative 3D navigation information.

Technique, Time Demand, Radiation Exposure, and Outcomes of Skin-anchored Intraoperative 3D Navigation in Minimally Invasive Posterior Cervical Laminoforaminotomy.

This was a retrospective review. The objective of this study was to describe our technique and evaluate the time demand, radiation exposure, and outcomes of minimally invasive posterior cervical laminoforaminotomy (MI-PCLF) using skin-anchored intraoperative navigation (ION). Although bone-anchored trackers are most commonly used for ION, a novel technique utilizing noninvasive skin-anchored trackers has recently been described for lumbar surgery and has shown favorable results. There are currently no reports on the use of this technology for cervical surgery. Time demand, radiation exposure, and perioperative outcomes of MI-PCLF using skin-anchored ION were evaluated. Twenty-one patients with 36 operative levels were included. Time for ION setup and operative time were a median of 34 and 62 minutes, respectively. Median radiation to the patient was 2.5 mGy from 10 seconds of fluoroscopy time. Radiation exposure to operating room personnel was negligible because they are behind a protective lead shield during ION image acquisition. There were no intraoperative complications or wrong-level surgeries. One patient required a repeat ION spin, and in 2 patients, ION was abandoned and standard fluoroscopy was used. Skin-anchored ION for MI-PCLF is feasible, safe, and accurate. It results in short operative times, minimal complications, low radiation to the patient, and negligible radiation to operating room personnel.

The effectiveness of preoperative assessment using a patient-specific three-dimensional pseudoarticulation model for minimally invasive posterior resection in a patient with Bertolotti\u2019s syndrome: a case report

BackgroundBertolotti’s syndrome is widely known to cause low back pain in young patients and must be considered as a differential diagnosis. Its treatment such as conservative therapy or surgery remains controversial. Surgical procedure is recommended for intractable low back pain. The three-dimensional (3D) lumbosacral transitional vertebrae anatomy should be completely understood for a successful surgery. Using an intraoperative 3D navigation and preoperative preliminary surgical planning with a patient-specific 3D plaster model contribute for safe surgery and good outcome.Case presentationA case of a 22-year-old Japanese male patient with intractable left low back pain due to lumbosacral transitional vertebrae with Bertolotti’s syndrome. The symptom resisted the conservative treatment, and anesthetic injection at pseudoarticulation only provided a short-term pain relief. Posterior resection using intraoperative three-dimensional (3D) navigation has been performed through microendoscopic view. Pseudoarticulation was totally and successfully resected in a safe manner.ConclusionsPreoperative surgical planning and rehearsal using a patient-specific 3D plaster model was greatly useful and effective for surgeons in performing accurate and safe pseudoarticulation resection.

Reconstruction of a Combined Frontal Bone and Orbital Roof Defect With Associated Meningoencephalocele Using 3D Modeling and 3D Navigation

Introduction: Orbital roof fractures are uncommon and normally associated with high energy trauma in which multiple other injuries are present. Most can be managed non-operatively with close observation. However, in a small proportion the defect is such that it permits the development of a meningoencephalocele, which can cause exophthalmos, a reduction in visual acuity and pain, all of which are unlikely to improve without surgical treatment. In light of their scarcity and the potential of serious risks with surgery that includes meningitis and visual disturbance (or even loss), thorough planning is required so that the meningoencephalocele can be reduced safely and the orbital roof adequately reconstructed. Methods: We report a case of a patient with a frontal bone defect, orbital roof fracture and associated meningoencephalocele that presented years after being involved in a road traffic accident in another country, who complained of a significant headache and orbital pain. The use of 3D modeling to help plan the surgery, and intraoperative 3D navigation to help negotiate the anterior skull base are described along with the reconstruction of the frontal bone and orbital roof using titanium mesh contoured on the 3D model. Conclusions: Although conservative management of orbital roof fractures predominates; those that are symptomatic, have associated neurologic symptoms or pose a risk to the eyesight warrant a surgical approach. The methods of repair, which center around separating the intracranial and intraorbital contents, are described in the context of this patient and previous cases, and a treatment algorithm is proposed.

Radiation Exposure to Scrub Nurse, Assistant Surgeon, and Anesthetist in Minimally Invasive Spinal Fusion Surgery Comparing 2D Conventional Fluoroscopy With 3D Fluoroscopy-based Navigation: A Randomized Controlled Trial.

A randomized controlled trial. To compare the radiation exposure with the scrub nurse, assistant surgeon, and anesthetist during minimally invasive transforaminal lumbar interbody fusion using conventional 2-dimensional (2D) fluoroscopy or 3D fluoroscopy-based navigation. Minimally invasive spinal fusion techniques are related to higher radiation exposures compared with open techniques. Especially the routinely exposed surgical staff faces the risks of increased radiation exposure. In total, 41 patients with planned monosegmental minimally invasive transforaminal lumbar interbody fusion were randomized into the intraoperative imaging techniques 2D fluoroscopy or 3D navigation. Eye lens and film dosemeters were attached to defined locations of the scrub nurse, assistant surgeon, and anesthetist. Mann-Whitney U and Wilcoxon-matched pairs signed-rank test were used to compare dosemeter readings. This study was registered with the German Clinical Trials Register (DRKS00004514). The radiation exposure per surgery was low for the scrub nurse, assistant surgeon, and anesthetist in both the 2D fluoroscopy and 3D navigation groups. The maximum average value of 0.057±0.031 mSv was measured on the unprotected chest of the assistant surgeon and was thus slightly above the lower detection limit of the dosemeters (0.044 mSv). The annual occupational dose limit would be exceeded at the earliest after 571 operations for the unprotected eye lens of the assistant surgeon. Minimally invasive lumbar fusion surgery is possible with comparatively low radiation exposure to the assisting operating room personnel without exceeding the annual maximum occupational radiation exposure. However, there is no definite dose value below which ionizing radiation poses no risk. Consequently, radiation sparing work routines should be strictly followed.

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.

Noninvasive patient tracker mask for spinal 3D navigation: does the required large-volume 3D scan involve a considerably increased radiation exposure?

Intraoperative 3D imaging and navigation is increasingly used for minimally invasive spine surgery. A novel, noninvasive patient tracker that is adhered as a mask on the skin for 3D navigation necessitates a larger intraoperative 3D image set for appropriate referencing. This enlarged 3D image data set can be acquired by a state-of-the-art 3D C-arm device that is equipped with a large flat-panel detector. However, the presumably associated higher radiation exposure to the patient has essentially not yet been investigated and is therefore the objective of this study. Patients were retrospectively included if a thoracolumbar 3D scan was performed intraoperatively between 2016 and 2019 using a 3D C-arm with a large 30 × 30-cm flat-panel detector (3D scan volume 4096 cm3) or a 3D C-arm with a smaller 20 × 20-cm flat-panel detector (3D scan volume 2097 cm3), and the dose area product was available for the 3D scan. Additionally, the fluoroscopy time and the number of fluoroscopic images per 3D scan, as well as the BMI of the patients, were recorded. The authors compared 62 intraoperative thoracolumbar 3D scans using the 3D C-arm with a large flat-panel detector and 12 3D scans using the 3D C-arm with a small flat-panel detector. Overall, the 3D C-arm with a large flat-panel detector required more fluoroscopic images per scan (mean 389.0 ± 8.4 vs 117.0 ± 4.6, p < 0.0001), leading to a significantly higher dose area product (mean 1028.6 ± 767.9 vs 457.1 ± 118.9 cGy × cm2, p = 0.0044). The novel, noninvasive patient tracker mask facilitates intraoperative 3D navigation while eliminating the need for an additional skin incision with detachment of the autochthonous muscles. However, the use of this patient tracker mask requires a larger intraoperative 3D image data set for accurate registration, resulting in a 2.25 times higher radiation exposure to the patient. The use of the patient tracker mask should thus be based on an individual decision, especially taking into considering the radiation exposure and extent of instrumentation.

Cranial facet joint injuries in percutaneous lumbar pedicle screw placement: a matched-pair analysis comparing intraoperative 3D navigation and conventional fluoroscopy

PurposeThe violation of the cranial adjacent facet is a frequent complication in lumbar instrumentations and can induce local pain and adjacent segment disease. Minimally invasive screw implantation is often stated as risk factor in comparison with open approaches. Percutaneous pedicle screw placement (PPSP) can be performed using single X-ray images (fluoroscopy) or intraoperative 3D navigation. The study compares top-level screws in percutaneous lumbar instrumentations regarding facet violations and screw pedicle position using navigation or fluoroscopy.MethodsPatients after lumbar PPSP were retrospectively separated according to the intraoperative technique: navigation (NAV) or fluoroscopy (FLUORO). Two blinded investigators graded the top-level screws regarding facet violations and pedicle breach in postoperative CT scans. Subsequent matched cohort analysis was performed for comparable groups.ResultsEvaluating 768 screws, we assessed 70 (9.1%) facet violations. Overall, 186 (24.2%) screws were implanted using navigation. There was no significant difference in the rate of facet violations between both imaging groups (NAV 19/186, 10.2%, FLUORO 51/582, 8.8%, p = 0.55). Totally, 728 (94.8%) of all screws showed a correct pedicle position. Most of the 40 unfavorable pedicle positions were placed by fluoroscopy (NAV 4/186, 2.2%, FLUORO 36/582, 6.6%, p = 0.03). The matched cohorts verified these results (facet violations: NAV 19/186, 10.2%, FLUORO 18/186, 9.7%, p = 0.55; pedicle penetrations: NAV 4/186, 2.2%, FLUORO 12/186, 6.9%, p = 0.04).ConclusionsBoth intraoperative imaging techniques allow lumbar PPSP with low rates of cranial facet violations if the surgeon intends to preserve facet integrity. Navigation was superior concerning accurate pedicle screw position, but could not significantly prevent facet violations.

Using lean principles to introduce intraoperative navigation for scoliosis surgery.

Intraoperative 3D navigation (ION) allows high accuracy to be achieved in spinal surgery, but poor workflow has prevented its widespread uptake. The technical demands on ION when used in patients with adolescent idiopathic scoliosis (AIS) are higher than for other more established indications. Lean principles have been applied to industry and to health care with good effects. While ensuring optimal accuracy of instrumentation and safety, the implementation of ION and its associated productivity was evaluated in this study for AIS surgery in order to enhance the workflow of this technique. The aim was to optimize the use of ION by the application of lean principles in AIS surgery. A total of 20 consecutive patients with AIS were treated with ION corrective spinal surgery. Both qualitative and quantitative analysis was performed with real-time modifications. Operating time, scan time, dose length product (measure of CT radiation exposure), use of fluoroscopy, the influence of the reference frame, blood loss, and neuromonitoring were assessed. The greatest gains in productivity were in avoiding repeat intraoperative scans (a mean of 248 minutes for patients who had two scans, and a mean 180 minutes for those who had a single scan). Optimizing accuracy was the biggest factor influencing this, which was reliant on incremental changes to the operating setup and technique. The application of lean principles to the introduction of ION for AIS surgery helps assimilate this method into the environment of the operating theatre. Data and stakeholder analysis identified a reproducible technique for using ION for AIS surgery, reducing operating time, and radiation exposure. Cite this article: Bone Joint J. 2020;102-B(1):5-10.

Minimal Invasive Percutaneous Kyphoplasty of C1 Lytic Lesion Using an Intraoperative 3D Imaging-Based Navigation System and Fluoroscopy

Background: Percutaneous kyphoplasty is a minimally-invasive techniques that aim to provide pain relief and bone stabilization by the injection of cement. Metastatic lesions of the atlas treated by this technique has been described in only few articles. Objective: We describe the use of kyphoplasty in a painful osteolytic lesion located in the left mass lateral of C1 with a postero lateral approach using 3D CT-scann intraoperative navigation system and fluoroscopy. Methods: A 58 year-old woman with metastastic breast neoplastic which admitted for treatment severe left-sided suboccipital exacerbated by head rotation and neck pain refractory to conventional medical treatment painkillers. CT scan and magnetic resonance imaging of the cervical spine revealed osteolytic destruction the left lateral mass of C1 . The patient underwent a percutaneous kyphoplasty managed using polymethylmetacrylate bone cement. Results: The patient reported post operative substantial pain relief . CT scan showed adequate filling of the osteolytic lesion without the obvious leakage of bone cement. the patient showed no clinical complications, while Clinical follow-up at 3 months revealed that this pain condition was improved and maintained. Conclusion: Minimally invasive percutaneous kyphoplasty using an intraoperative 3D navigation system and fluroscopy with postero lateral approach is a safe and effective alternative reducing post-operative morbidity and effective possibility in selected patients with C1 metastasis

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

Retrospective cohort. 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. 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. 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. 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. Skin-anchored ION does not increase time-demand compared with fluoroscopy, is feasible, safe and accurate, and results in low radiation exposure. 3.

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.

Real-time intraoperative 3D image intensifier-based navigation in reversed shoulder arthroplasty- analyses of image quality

BackgroundDue to the high anatomical variability and limited visualization of the scapula, optimal screw placement for baseplate anchorage in reversed total shoulder arthroplasty (rTSA) is challenging. Image quality plays a key role regarding the decision of an appropriate implant position. However, these data a currently missing for rTSA and were investigated in the present study. Furthermore, the rate of required K-wire changes for the central peg as well as post-implantation inclination and version were assessed.MethodsIn ten consecutive patients (8 female, 86 years, range 74–94) with proximal humeral fracture and indication for rTSA, an intraoperative 3D-scan of the shoulder with a 3D image intensifier (Ziehm Vision FD Vario 3D© [Ziehm Imaging GmbH, Nürnberg, Germany]) was performed after resection of the humeral head. Using the Vectorvision© Software (Brainlab AG, Feldkirchen, Germany), the virtual anatomy was compared to the visible anatomical landmarks. After implantation of the baseplate, a 3D scan was performed. All 3D scans included multiplanar reconstruction (MPR) and the cinemode to examine screw and baseplate placement. The rate of required K-wire changes was assessed. The intraoperative 3D image quality (modified visual analogue scale [VAS] and point system) was assessed before and after implantation of the glenoid component. Inclination and version were determined in post-implantation scans.ResultsThe virtually presented anatomical landmarks always correlated to the anatomical visible points indicating an good virtual accuracy. The central K-wire position was corrected in three cases due to a deviation from the face plane technique position. The VAS was higher for the pre-implantation MPR (6.7, range 5–8) compared to the post-implantation acquired MPR (5.1, range 4–6; p = 0.0002). The point system showed a reduced quality in all subcategories, especially regarding the grading of the articular surfaces. The preoperative (7.9, range 6–9) and post-implantation (7.9, range 6–9) cinemode displayed no significant differences (p = 0.6).ConclusionThe present study underlines the need for the improvement of 3D image intensifiers algorithms to reduce artifact associated impaired image quality to enhance the benefit of real-time intraoperative 3D scans and navigation.

Wednesday, September 26, 2018 7:35 AM–9:00 AM ePosters: P34. Axial rotation correction in adolescent idiopathic scoliosis with pedicle screw construct

BACKGROUND CONTEXT Adolescent idiopathic scoliosis (AIS) is a three-dimensional deformity characterized by tilt and rotation of the spine. As rib prominence is related to the vertebral rotation, derotation of the spine to reduce deformity is desirable. At our institution, posterior spinal fusions for AIS are performed with the use of intraoperative 3D fluoroscopic imaging with navigation. Scans of the entire operative curve are taken before and after instrumentation, resulting in tomographs in which the accuracy of pedicle screw placement and the change in axial rotation can be measured. METHODS Posterior spinal fusion with pedicle screw and rod instrumentation with the use of intraoperative 3D fluoroscopic imaging and navigation was performed. Pedicle screws were placed using navigation, following standard posterior approach. The most cephalad level of instrumentation was secured with hooks. After placement of pedicle screws and a convex rod, derotation was performed using uniaxial screws with tubes over screwdrivers. A second scan was performed to ensure the appropriate position of all screws, allowing measurement of derotation intraoperative. Data collection: Institutional review board approval was obtained for retrospective review of patient charts and images, and for the creation of a patient database. All patients who received posterior spinal fusion for AIS between 2008 and 2010 were included in the database. Inclusion criteria for this review were limited to patients with AIS and with greater than 2years follow-up. This resulted in a total of 54 patients for inclusion. Imaging taken before and after instrumentation and rod de-rotation maneuver was reviewed. For each patient, apical and neutral vertebrae were identified on the standing PA radiograph. The angle of rotation (RA sag) was then measure on the axial 3D images for the apical and neutral vertebrae, by the method described by Aaro and Dahlborn. The difference between the RA sag of these two vertebrae was defined as the axial rotation measured on the pre- and post-instrumented axial images. PA standing scoliosis view was also taken on fourth postoperative day. Cobb angles were measured from each of these radiographs and submitted for analysis. Statistical analysis: Mixed linear models were used to predict axial rotation correction and calculate LSMEANS with 95% confidence intervals. Covariates included gender and continuous age. Logistic regression was employed to estimate the odds of non-normal status postsurgery when compared to normal with presurgery standing Cobb as the independent variable. The one patient with a Lenke classification of five was removed for this analysis. All analyses were conducted using the statistical package SAS, version 9.3. (SAS Institute Inc., Cary, North Carolina) RESULTS Axial rotation correction overall was a 28.7% improvement postoperatively. This change meets statistical significance (p=.0202) when adjusting for age and gender. The change in axial rotation is significantly negatively correlated with age, indicating the change in axial rotation tends to decrease as age increases. Discussion: Our study was able to show a significant improvement in axial rotation in our group of patients. The manner in which the images were taken provides, by our estimation, a standardized method of image-gathering that is most reproducible and has the least amount of variability. General anesthesia and positioning alone have shown to decrease the magnitude of measured curves. Lee et al. showed a decrease of as much as 74% in Cobb angles and 25.7% rotational measurement (using Pedriolle torismeter) by placing a patient under anesthesia and on the operative table. Our study has the unique advantage of having all images taken after dissection and preparation of the spinal elements has occurred, removing an additional layer of variability. CONCLUSIONS Derotation maneuver using convex pedicle screws significantly reduced axial rotation of the spine. This study validates one technique of derotation. Vertebral derotation resulting from correction maneuver can be quantified, making comparisons of different techniques and instrumentation possible. Future studies using different instrumentations and derotation techniques should make comparisons possible.

Comparative Study of C-Arms for Intraoperative 3-dimensional Imaging and Navigation in Minimally Invasive Spine Surgery Part II

Study Design: A radiation exposure study in vitro. Objective: This study aimed to compare the radiation exposure of 2 different 3-dimensional (3D) C-arm devices on an anthropomorphic phantom. Summary of Background Data: Minimally invasive pedicle screw placement requires intraoperative imaging techniques for visualization of the unexposed spine. Mobile 3D C-arms compose a 3D image data set out of multiple successive fluoroscopic images. Methods: We compared the 3D C-arm devices Siremobil Iso-C 3D (Siemens Sector Healthcare, Erlangen, Germany) and Vision FD Vario 3D (Ziehm Imaging, Nuremberg, Germany) regarding their radiation exposure. For this purpose, dosimeters were attached on an anthropomorphic phantom at various sites (eye lenses, thyroid gland, female, and male gonads). With each C-arm, 10 automated 3D scans as well as 400 fluoroscopic images were performed on the cervical and lumbar spine, respectively. Results: The Vision FD Vario 3D generally causes higher radiation exposures than the Siremobil Iso-C 3D. Significantly higher radiation exposures were assessed at the eye lenses performing cervical (294.1 vs. 84.6 μSv) and lumbar 3D scans (22.5 vs. 11.2 μSv) as well as at the thyroid gland performing cervical 3D scans (4405.2 vs. 2761.9 μSv). Moreover, the Vision FD Vario 3D caused significantly higher radiation exposure at the eye lenses for standard cervical fluoroscopic images (3.2 vs. 0.4 μSv). Conclusions: 3D C-arms facilitate minimally invasive and accurate pedicle screw placement by providing 3D image datasets for intraoperative 3D imaging and navigation. However, the hereby potentially increased radiation exposure has to be considered. In particular, the Vision FD Vario 3D appears to generally evoke higher radiation exposures than the Siremobil Iso-C 3D. Well-indicated application of ionizing radiation and compliance with radiation protection principles remain mandatory to keep radiation exposure to patient and staff as low as reasonably achievable.

Intraoperative 3D imaging in spinal surgery

Intraoperative imaging during spinal interventions has experienced significant developments over the last two decades. By the introduction of flat screen detectors, 3D imaging has been made possible and easier and by developing compact and mobile systems computed tomography can even be used in the operating theater. Presentation of modern intraoperative 3D imaging and navigation in spinal surgery. The techniques of intraoperative 3D imaging and navigation during spinal procedures are presented based on the currently available literature and own experiences at a German national spine and trauma center. The use of flat panel detectors and the possibility of 3D visualization nowadays substantially facilitate the use of navigation and allow certain control of surgical results even during the intervention. Radiation exposure of the whole team in the operating theater can be significantly reduced by the new techniques. The advantages of intraoperative 3D imaging with a clear improvement of visualization for spinal surgeons and the certain control of materials at the end of the operation are obvious. Even the use of navigation has been greatly simplified and can therefore lead to an even greater precision and less radiation exposure. There are even more sophisticated developments, such as operation suites and intraoperative computed tomography but these are initially reserved for selected centers.

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

Introduction. A new generation of iCT scanner, Airo®, has been introduced. The purpose of this study is to describe how Airo facilitates minimally invasive transforaminal lumbar interbody fusion (MIS-TLIF). Method. We used the latest generation of portable iCT in all cases without the assistance of K-wires. We recorded the operation time, number of scans, and pedicle screw accuracy. Results. From January 2015 to December 2015, 33 consecutive patients consisting of 17 men and 16 women underwent single-level or two-level MIS-TLIF operations in our institution. The ages ranged from 23 years to 86 years (mean, 66.6 years). We treated all the cases in MIS fashion. In four cases, a tubular laminectomy at L1/2 was performed at the same time. The average operation time was 192.8 minutes and average time of placement per screw was 2.6 minutes. No additional fluoroscopy was used. Our screw accuracy rate was 98.6%. No complications were encountered. Conclusions. Airo iCT MIS-TLIF can be used for initial planning of the skin incision, precise screw, and cage placement, without the need for fluoroscopy. “Total navigation” (complete intraoperative 3D navigation without fluoroscopy) can be achieved by combining Airo navigation with navigated guide tubes for screw placement.