Use Of O-arm Research Articles

Surgical outcomes of intraoperative O-arm versus C-arm fluoroscopy in occipitocervical fixation: a retrospective analysis

Purpose This study aims to compare the effect of using O-arm and C-arm fluoroscopy on the surgical outcomes of occipitocervical fixation. Methods The study included patients who underwent occipitocervical fixation using O-arm or C-arm between 2005 and 2021. Of 56 patients, 34 underwent O-arm-assisted surgery (O-group) and 22 underwent C-arm-assisted surgery (C-group). We assessed surgical outcomes, including operative time, intraoperative blood loss, perioperative complications, and bone union. Results Almost half of the patients had rheumatoid arthritis-related disorders in both groups. Sixteen cases (47.1%) in the O-group and 12 cases (54.5%) in the C-group were fixed from occipito (Oc) to C3, 12 cases (38.2%) in the O-group and 7 cases (31.8%) in the C-group from Oc to C4-7, 5 cases (14.7%) in the O-group, and 3 cases (13.6%) in the C-group from Oc to T2 (p = 0.929). There was no significant difference in operative time (p = 0.239) and intraoperative blood loss (p = 0.595) between the two groups. Dysphagia was the most common complication in both groups (O-group vs. C-group, 11.7% vs. 9.1%). Regarding implant-related complications, occipital plate dislodgement was observed in four cases (18.2%) in the C-group (p = 0.02). The bone union rate was 96.3% in the O-group and 93.3% in the C-group (P = 1). Conclusions O-arm use is associated with a reduced rate of occipital plate dislodgment and has a similar complication incidence compared with C-arm-assisted surgery and does not prolong operative time despite the time needed for setting and scanning. Accordingly, an O-arm is safe and useful for occipitocervical fixation surgery.

O-Arm Accuracy and Radiation Exposure in Adult Deformity Surgery

In long thoracolumbar deformity surgery, accurate screw positioning is critical for spinal stability. We assessed pedicle and pelvic screw accuracy and radiation exposure in patients undergoing long thoracolumbar deformity fusion surgery (≥4 levels) involving 3-dimensional fluoroscopy (O-Arm/Stealth) navigation. In this retrospective single-center cohort study, all patients aged >18years who underwent fusion in 2016-2018 were reviewed. O-Arm images were assessed for screw accuracy. Effective radiation doses were calculated. The primary outcome was pedicle screw accuracy (Heary grade). Secondary outcomes were pelvic fixation screw accuracy, radiation exposure, and screw-related perioperative and postoperative complications or revision surgery within 3years. Of 1477 pedicle screws placed in 91 patients (mean 16.41±5.6 screws/patient), 1208 pedicle screws (81.8%) could be evaluated by 3-dimensional imaging after placement. Heary Grade I placement was achieved in 1150 screws (95.2%), Grade II in 47 (3.9%), Grade III in 10 (0.82%), Grade IV in 1 (0.08%), and Grade V in 0; Grade III-V were replaced intraoperatively. One of 60 (1.6%) sacroiliac screws placed showed medial cortical breach and was replaced. The average O-Arm-related effective dose was 29.54±14.29mSv and effective dose/spin was 8.25±2.65mSv. No postoperative neurological worsening, vascular injuries, or revision surgeries for screw misplacement were recorded. With effective radiation doses similar to those in interventional neuroendovascular procedures, the use of O-Arm in multilevel complex deformity surgery resulted in high screw accuracy, no need for surgical revision because of screw malposition, less additional imaging, and no radiation exposure for the surgical team.

Congenital agenesis of lumbo-sacral pedicles with associated anomalies: case report with an emphasis on the use of O-arm, navigation in the management with literature review

BackgroundCongenital spinal pedicle agenesis is rare. The majority of cases are asymptomatic. Few present with either low back pain or radiculopathy. Pedicle screw insertion may pose difficulties in view of abnormal anatomy.Case presentationBetween Jan 2005 and March 2021, all the data were retrospectively reviewed for the cases operated for congenital anomalies. Three such cases were operated. Case 1 had bilateral agenesis of L5 vertebra with an ectopic kidney in right iliac fossa, absent uterus, absent ovaries and vaginal atresia. Case 2 had absent S1 pedicle with conjoint left L5 nerve root. Case 3 had hypoplastic left L5 pedicle, contained disc herniation, facetal arthropathy. Pedicle screws were placed using O-arm and navigation.ConclusionPedicle agenesis increases the difficulty in pedicle screw fixation and fusion. Anomalous facet and conjoint nerve root need to be looked for intraoperatively. Use of O-arm and CT navigation is of great help in getting safe and accurate anchor points for screw placement avoiding neurological injury.

Association between intraoperative computed tomography navigation system and incidence of surgical site infection in patients with spinal surgeries: a retrospective analysis

PurposeAlthough the use of intraoperative computed tomography (CT)-based navigation systems is unlikely to cause intraoperative contamination more than the use of intraoperative fluoroscopy, the association between intraoperative CT/navigation and surgical site infections (SSIs) remains unclear. We investigated the incidence of SSIs and the association between intraoperative CT/navigation and SSIs for spinal surgeries.MethodsOf the 512 patients who underwent spinal surgery between April 2016 and December 2020, 304 underwent C-arm intraoperative fluoroscopy and/or Medtronic O-arm intraoperative CT/navigation system. We investigated the incidence of SSIs in patients with four techniques; no intraoperative imaging C-arm only, O-arm only, and both O- and C-arm used. Multivariate logistic analyses were conducted using the prevalence of SSIs as the dependent variable. The independent variables were age, sex, and potential confounders including preoperative Japanese Orthopaedic Association (JOA) score, use of instrumentation, C-arm, and/or O-arm.ResultsThe incidence of the SSIs in patients with no imaging, C-arm only, O-arm only, and both modalities used was 1.9%, 7.3%, 4.7%, and 8.3%, respectively. There was no significant difference in the incidence of SSIs between the four techniques. Multivariate logistic analyses showed a significant correlation between the prevalence of SSI and JOA scores (odds ratio, 0.878; 95% CI 0.759–0.990) and use of instrumentation (odds ratio, 6.241; 95% CI 1.113–34.985), but not use of O-arm.ConclusionsThe incidence of the SSIs in patients with only O-arm used was 4.7%. Preoperative clinical status and use of instrumentation, but not use of the O-arm, were associated with SSIs after spinal surgeries.

Use of O-arm With Intraoperative Arteriography for Localization and Stealth Navigation of the Vertebral Arteries During Posterior Cervical Spine Surgery.

Vertebral artery injury (VAI) can be a devastating complication during cervical spine surgery. Although considered a rare occurrence overall, incidences of VAI have been reported in the ranges of 0.07% to 8%. Such injuries have the potential for catastrophic consequences, including blood loss, permanent morbid neurologic injury, and even death. The introduction of intraoperative navigation using either preoperative or intraoperative imaging has now been widely adopted in current practice so as to try and minimize adverse outcomes while giving real-time, dynamic information of the operative field. The use of the O-arm Surgical Imaging System during cervical spine surgery allows one to obtain high-resolution, accurate intraoperative imaging, and when used in concert with forms of intraoperative navigation, it can help with instrumentation and safety. However, patients undergoing cervical spine surgery do not routinely undergo preoperative vascular imaging, particularly with regard to anterior cervical or posterior high-cervical surgeries, where the incidence of VAI, in comparison with other cervical surgeries, has been reported to be the highest. Here we present the use of intraoperative O-arm-based arteriography for integration with navigation for vertebral artery localization during C1 to C3 posterior instrumentation and fusion of an unstable C2 fracture in a 54-year-old man. The patient did not experience any intraoperative VAI and was subsequently discharged with no focal neurologic deficits. Detailed in our report is our protocol and procedure for obtaining and using intraoperative angiographic images. Case report detailing O arm for intraoperative identification of vertebral arteries during C1-C3 posterior instrumentation and fusion with pre-operative unilateral vertebral artery injury.

Use of O-arm with neuronavigation in percutaneous vertebroplasty reduces the surgeon's exposure to intraoperative radiation.

IntroductionPercutaneous vertebroplasty is commonly used to treat spinal fractures. The authors compare radiation exposure as potential risk for the surgical team during vertebroplasty guided by O-arm combined with neuronavigation versus vertebroplasty guided by C-arm fluoroscopy.Material and methodsThe clinical material consisted of a group of 29 patients (44 vertebrae) with fractures of the thoracolumbar spine treated with percutaneous vertebroplasty guided by O-arm with neuronavigation. In this new method, the operating room staff leaves the operating room for the duration of the 3D scan of the appropriate spine section using the O-arm. In the next stage, the needle of the vertebroplasty system is introduced using only neuronavigation without the need for a radiological view. Finally, the cement injection was made under O-arm fluoroscopic control. The comparison group consisted of a group of 35 patients (40 vertebrae) treated with the classical method using C-arm fluoroscopy. The two methods were compared in terms of the average dose of emitted ionizing radiation through the device (O-arm vs. C-arm) to which surgeons are exposed during percutaneous vertebroplasty.ResultsAs a result of vertebroplasty procedures guided by neuronavigation, a statistically significant difference between the values of mean dose of radiation emitted by O-arm and C-arm systems was noted. The O-arm emitted 912 cGy/cm2 vs. 1722 cGy/cm2 emitted by the C-arm during fluoroscopically assisted procedures and 601.28 cGy/cm2 vs. 1506.86 cGy/cm2 per vertebrae.ConclusionsDuring vertebroplasty with the O-arm combined with neuronavigation the radiation dose is significantly lower as compared with the C-arm used for fluoroscopic guidance, minimizing the potential risk of radiation exposure to surgeons.

Assisted dorso-lumbar instrumentation with O-arm neuronavegation and minimally invasive surgery: clinical-surgical outcome.

To evaluate the clinical-surgical outcomes after dorso-lumbar instrumentation using O-arm assisted neuronavigation and minimally invasive surgery. In this retrospective cohort, 104 patients who underwent dorso-lumbar instrumentation with the use of O-arm from September 2013 to May 2020 were studied. Variables investigated included: symptoms, number of screws, levels approached, bleeding, surgical time, hospital stay, complications and clinical improvement after the surgical procedure. The most frequent symptoms were: unilateral or bilateral radiculopathy of the pelvic extremities, paresthesia, mechanical low back pain and progressive decrease in strength. A total of 542 screws were placed, with the lumbar spine being the site with the highest prevalence. The average bleeding, surgical time, and hospital stay was: 50 ml, 160 minutes, and 24 hours, respectively. The most frequent complications were: Residual neuropathy, dura mater tear and surgical site infection. Clinical improvement at 24 hours, 4 weeks and 6 months was achieved in: 77.3%, 86.5% y 94.8% of the patients, respectively. Neuronavigation with the use of O-arm along with mini-open surgery approach results in good clinical-surgical outcomes in the correction of complex disorders of the dorso-lumbar spine.

Patient Radiation Exposure Associated With the Use of Computer Navigation During Spinal Fusion.

Calibration of computer navigation for spinal fusion is most commonly conducted using either a preoperative computed tomography (CT) scan or intraoperative O-arm scanning. This study aimed to directly compare patient radiation exposure from intraoperative O-arm use for pedicle screw placement versus typical diagnostic lumbar spine CT studies. A retrospective review of patients undergoing O-arm navigated lumbar spine fusion procedures was performed to record radiation exposure as the primary outcome, as well as surgical and demographic details. The same was done for a control group of patients undergoing lumbar spine CT scans. A total of 83 patients undergoing lumbar spine fusion with O-arm navigation were included, as well as 105 unique patients who underwent a lumbar spine CT. The 2 groups were similar in terms of average age (60.2 versus 60.5, P = .90), average height (170 cm versus 169 cm, P = .50), and average weight (92.6 kg versus 90.9 kg, P = .62). Dose-length product for O-arm navigated procedures was 798.3 mGy-cm and 924.2 mGy-cm for CT scans (P = .064). Subgroup analysis revealed 18 patients who had both an O-arm navigated surgery and a lumbar spine CT. In this group the average dose-length product for O-arm surgeries was 806.2 mGy-cm and 822.1 mGy-cm for CT scans (P = .92) CONCLUSION: This study revealed no statistically or clinically significant differences between patient radiation exposure for O-arm operative navigation compared to lumbar spine CT. Given the similarity in radiation exposure, surgeons should rely on other factors to guide decision making in regard to mode of imaging for navigation. Knowledge of this comparison and total radiation exposure will also be useful for patient education and shared decision making in regard to navigated procedures.

Surgical Results of Intraoperative C-arm Fluoroscopy Versus O-arm in Transarticular Screw Fixation for Atlantoaxial Instability

This study compared the surgical results of transarticular screw (TAS) fixation for atlantoaxial instability between C-arm fluoroscopy and O-arm. Of 58 patients who underwent TAS fixation for atlantoaxial instability, 35 underwent C-arm-assisted surgery (C-group) and 23 underwent O-arm-assisted surgery (O-group). In total, 78 TASs were placed: 39 in the C-group and 39 in the O-group. Unilateral and bilateral TAS fixation was performed in 38 and 20 patients, respectively. All patients underwent Brook's procedure with TAS. TAS fixation accuracy on postoperative computed tomography, operative time, intraoperative bleeding, perioperative complications, and bone union were evaluated. Screw accuracy was assessed using Neo's classification: grade (G) 0, no perforation; G1, perforation <2 mm; G2, perforation 2-4 mm; G3, perforation >4 mm. TAS fixation accuracy was greater in the O-group than the C-group: G0: 38, 97.4%; G1: 1, 2.6% (O-group) vs G0: 22, 56.4%; G1: 11, 28.2%; G2: 3, 7.7%; G3: 3, 7.7% (C-group) (P < 0.001). Median operative time and median blood loss were similar between both groups. Bone union rate was greater with bilateral than unilateral TAS fixation (P <0.05). There were no complications regarding screw malposition. Deep wound infection was observed in 1 case in the C-group. O-arm use improved TAS fixation accuracy. Blood loss was equivalent between the groups. O-arm-assisted TAS fixation did not prolong operative timedespite the time required for setting and scanning. The O-arm is safe and useful for TAS fixation in atlantoaxial instability.

Cervical Pedicle Screw Insertion Using O-Arm-Based 3D Navigation: Technical Advancement to Improve Accuracy of Screws

This study aimed to report the technical advancement to improve the accuracy of cervical pedicle screw (CPS) placement using O-arm-based 3D navigation. Sixty-four patients who underwent CPS using O-arm in the spine level of C2 to C7 between June 2013 and February 2020 were involved. In the first phase, a reference frame was placed onto the spinous process of the cranial vertebrae and used it at a maximum of 3 vertebral levels. The navigation guide sleeve was used to drill a screw hole. In the second phase, a reference frame that can hold 3 vertebrae was introduced. In the third phase, a drill guide sleeve to minimize bending of the drill tip was developed. In the fourth phase, navigated surgical drill was introduced. Screw accuracy was assessed using Neo classification: grade (G) 0, no perforation; G1, perforation <2 mm; G2, perforation 2-4 mm; and G3, perforation >4 mm. Mean age at surgery was 67 (19-88) years. A total of 317 CPSs were inserted. In total, 83 screws were inserted in the first phase, 60 in the second phase, 87 in the third phase, and 87 in the fourth phase. The total proportion of malpositioning was 3.8% (12/317 screws) and all were G1; 6.0% (5/83 screws) in the first phase, 8.3% (5/60 screws) in the second phase, 1.2% (1/87 screws) in the third phase, and 1.2% (1/87 screws) in the fourth phase (P < 0.05). O-arm use improved CPS placement accuracy with the advancement of techniques and instruments.

Surgical treatment of patients with primary and metastatic spinal tumor with use of the O-Arm intraoperative portable computed tomography scanner

The study objective is to demonstrate our experience of employment of O-Arm intraoperative portable сomputed tomography scanner combined with navigation system Stealth Station Treon Plus (Medtronic Navigation) during decompressive-stabilizing surgeries for patients with primary and metastatic spinal tumors.Materials and methods. We have reviewed results of surgical treatment of 44 patients (24 males and 20 females, average age is 54.3 ± 1.8), who were hospitalized and operated in the department of spinal neurosurgery in Federal Centre of Neurosurgery (Tyumen). All surgeries were performed by one surgical team in the period of April 2011 to June 2017. All patients underwent full clinical examination according to diagnostic algorithm, including assessment of general condition, degree of bone and visceral dissemination, neurological status, quality of life, pain syndrome intensity. The most common cause of vertebral lesions was plasma cell myeloma (15 patients, 34.1 %), metastatic spinal lesions (12 patients, 27.3 %). Patients were subjected to posterior decompression and stabilization with total and subtotal excision of mass lesions. Assessment of degree of decompression and transpedicular fixation were carried out visually using O-Arm combined with navigation station.Results. In 6 to 12 months after surgery 79.5 % of patients demonstrated significant improvement of neurological status, specifically a decrease of conduction and sensory disorders. Degree of pain syndrome was reduced by 3.6 times. Using O-Arm combined with navigation station we placed screws adequately in 99.6 % of the cases. The main technical problem that occurred during the surgery was the failure of navigation system caused by: defect of reflective spheres, distant installation and shift of referential frame, aging of Jamshidi needle, malfunction of navigation camera, failure of data transfer from navigation station.Conclusion. The use of O-Arm combined with navigation station for decompressive and stabilizing surgeries in patients with spine and spinal cord tumors let us perform surgeries with 3D control and navigation, conduct surgeries in areas where it is hard to determine surgical landmarks, ensure precision of transpedicular screw implantation, accomplish total resection of mass lesions with minimal blood loss and less aggressive surgical intervention and properly decompress the spinal canal which, eventually, result in positive anatomical and functional characteristics, and contribute to good general outcome of surgical intervention.Conflict of interest. The authors declare no conflict of interest.Informed consent. All patients gave written informed consent to participate in the study and to the publication of their data.

Intraoperative Use of O-arm in Pediatric Cervical Spine Surgery.

Traditionally, fluoroscopy and postoperative computed tomographic (CT) scans are used to evaluate screw position after pediatric cervical spine fusion. However, noncontained screws detected postoperatively can require revision surgery. Intraoperative O-arm is a 3-dimensional CT imaging technique, which allows intraoperative evaluation of screw position and potentially avoids reoperations because of implant malposition. This study's objective was to evaluate the use of intraoperative O-arm in determining the accuracy of cervical implants placed by a free-hand technique using anatomic landmarks or fluoroscopic guidance in pediatric cervical spine instrumentation. A single-center retrospective study of consecutive examinations of children treated with cervical spine instrumentation and intraoperative O-arm from 2014 to 2018 was performed. In total, 44 cases (41 children, 44% men) with a mean age of 11.9 years (range, 2.1 to 23.5 y) were identified. Instability (n=16, 36%) and deformity (n=10, 23%) were the most frequent indications. Primary outcomes were screw revision rate, neurovascular complications caused by noncontained screws, and radiation exposure. A total of 272 screws were inserted (60 occipital and 212 cervical screws). All screws were evaluated on fluoroscopy as appropriately placed. Four screws (1.5%) in 4 cases (9%) were noncontained on O-arm imaging and required intraoperative revision. A mean of 7.7 levels (range, 5 to 13) were scanned. The mean CT dose index and dose-length product were 15.2±6.87 mGy and 212.3±120.48 mGy×cm. Mean effective dose was 1.57±0.818 mSv. There was no association between screw location and noncontainment (P=0.129). No vertebral artery injuries, dural injuries, or neurologic deficits were related to the 4 revised screws. Intraoperative non-navigated O-arm is a safe and efficient method to evaluate screw position in pediatric patients undergoing cervical spine instrumentation. Noncontained screws were detected in 9% of cases (n=4). O-arm delivers low radiation doses, allows for intraoperative screw revision, and negates the need for postoperative CT scans after confirmation of optimal implant position. Level IV.

Accuracy and Safety in Screw Placement in the High Cervical Spine: Retrospective Analysis of O-arm-based Navigation-assisted C1 Lateral Mass and C2 Pedicle Screws.

This study was a retrospective analysis. The purpose of present study was to evaluate accuracy, efficiency, and safety of intraoperative O-arm-based navigation system for the placement of C1 lateral mass screw (C1LMS) and C2 pedicle screws (C2PSs) in high cervical spine operations. High screw misplacement rates, various pedicle morphometry and vertebral body size variations have led to a search of image-guided systems to improve the surgical accuracy of screw insertion in high cervical spine. The use of O-arm has been proposed for more accurate and efficient spinal instrumentation. Between June 2009 and August 2016, a total of 48 patients with atlantoaxial instability were surgically treated using the image-guidance system. To reconstruct atlantoaxial instability, we have been using Harm's technique of C1LMS and C2PS fixations. A frameless, stereotactic O-arm-based image-guidance system was used for correct screw placement. Postoperative computed tomographic scan with multiplanar reconstructions were used to determine the accuracy of the screw placement. A total of 182 screws, including 90 C1LMS and 92 C2PSs were inserted using image-guidance system. In total, 4.4% (4/90) of C1LMS and 7.6% (10/92) of C2PS had cortex violation over 2 mm and considered as "significant." Among the significant cortex violations, "unexpected breech" was 3.3% of all the screws inserted. Two (2.1%) screws inserted had perforated the vertebral artery canal and iatrogenic vertebral artery stenosis was proved with postoperative computed tomography angiography. When divided into time periods, 60% of significant breech occurred during the beginning stage, 40% during adaptation stage and none during expert stage. In this study, the authors demonstrated that use of image-guidance system seems to be beneficial for high cervical instrumentation which requires much experience and steep learning curves. However, incidence of cortex violation does not disappear completely due to the close proximity to spinal canal and surrounding vessels.

A spatial registration method for navigation system combining O-arm with spinal surgery robot

The minimally invasive surgery in spinal surgery has become increasingly popular in recent years as it reduces the chances of complications during post-operation. However, the procedure of spinal surgery is complicated and the surgical vision of minimally invasive surgery is limited. In order to increase the quality of percutaneous pedicle screw placement, the O-arm that is a mobile intraoperative imaging system is used to assist surgery. The robot navigation system combined with O-arm is also increasing, with the extensive use of O-arm. One of the major problems in the surgical navigation system is to associate the patient space with the intra-operation image space. This study proposes a spatial registration method of spinal surgical robot navigation system, which uses the O-arm to scan a calibration phantom with metal calibration spheres. First, the metal artifacts were reduced in the CT slices and then the circles in the images based on the moments invariant could be identified. Further, the position of the calibration sphere in the image space was obtained. Moreover, the registration matrix is obtained based on the ICP algorithm. Finally, the position error is calculated to verify the feasibility and accuracy of the registration method.

Intraoperative radiation exposure in spinal scoliosis surgery for pediatric patients using the O-arm® imaging system.

The O-arm® navigation system allows intraoperative CT imaging that can facilitate highly accurate instrumentation surgery, but radiation exposure is higher than with X-ray radiography. This is a particular concern in pediatric surgery. The purpose of this study is to examine intraoperative radiation exposure in pediatric spinal scoliosis surgery using O-arm. The subjects were 38 consecutive patients (mean age 12.9years, range 10-17) with scoliosis who underwent spinal surgery with posterior instrumentation using O-arm. The mean number of fused vertebral levels was 11.0 (6-15). O-arm was performed before and after screw insertion, using an original protocol for the cervical, thoracic, and lumbar spine doses. The average scanning range was 6.9 (5-9) intervertebral levels per scan, with 2-7 scans per patient (mean 4.0 scans). Using O-arm, the dose per scan was 92.5 (44-130) mGy, and the mean total dose was 401 (170-826) mGy. This dose was 80.2% of the mean preoperative CT dose of 460 (231-736) mGy (P=0.11). The total exposure dose and number of scans using intraoperative O-arm correlated strongly and significantly with the number of fused levels; however, there was no correlation with the patient's height. As the fused range became wider, several scans were required for O-arm, and the total radiation exposure became roughly the same as that in preoperative CT. Use of O-arm in our original protocol can contribute to reduction in radiation exposure.

O-arm with navigation versus C-arm: a review of screw placement over 3 years at a major trauma center

Introduction: There is a relatively high incidence of screw misplacement during spinal instrumentation due to distortion of normal anatomy following spinal trauma. The O-arm is the next-generation spinal navigation tool that provides intraoperative 3-D imaging and navigation for spine surgeries.Aims and objectives: To evaluate and compare the use of O-arm as compared to C-arm for spinal trauma in a Level I trauma center in India.Materials and methods: In this retrospective study over 3 years (July 2010–April 2013), All patients of spinal injury who underwent spinal instrumentation were divided into O-arm group and C-arm group. Accuracy of screw placement was assessed during each surgery in both groups.Results: A total of 587 patients were evaluated during the study period. There were 278 patients in O-arm group and 309 patients in C-arm group. Both groups were well matched in mean age (27.7 vs. 28.9 years), ASIA grades, and level of injury. The number of screws placed was significantly higher in the C-arm group as compared to the O-arm group (2173 vs. 1720). However, the O-arm group had significantly less screw malplacement rate of 0.93% (n = 16) as compared to malplacement rate in C-arm group of 8.79% (n = 191, p < 0.05).Conclusion: Use of O-arm imaging system ensures accurate screw placement and dramatically decreases screw malplacement rate, thus providing better patient safety. Its use is especially beneficial in academic and teaching centers where novice surgeons can attain results equivalent to that of experts in spinal instrumentation.

Predictors of variability in the length of surgery of posterior instrumented arthrodesis in patients with adolescent idiopathic scoliosis.

The most common corrective surgery for adolescent idiopathic scoliosis (AIS) is posterior instrumented spinal fusion, which is a relatively lengthy procedure. Longer procedures are known to have higher rates of negative outcomes and higher economic costs across the surgical specialties. The purpose of this study is to identify the factors that influence the length of this operation in AIS patients. This was an institutional review board-approved, retrospective cohort study. All primary posterior instrumented arthrodesis procedures in 2011-2013 performed by three surgeons on AIS patients at a tertiary care hospital were included. Age, race, sex, BMI, Cobb angle, curve flexibility, Lenke classification, number of levels fused, number of screws used, osteotomy use, intraoperative O-arm use, and length of surgery (time from incision to closure) were obtained from the electronic medical record. Multivariable linear regression analysis was used to determine independent predictors of length of surgery, and standardized regression coefficients were calculated to compare the relative magnitude of significant variables. A total of 95 procedures were included. The average length of surgery was 375 ± 72.7 min. The multivariable linear regression analysis contained the variables Cobb angle, number of screws used, osteotomy use, Lenke curve type, surgeon, patient age, and sex. The regression identified the number of screws used [β=4.72, P=0.003, 95% confidence interval (CI) 1.7-7.8], osteotomy use (β = 50.2, P = 0.004, 95% CI 16.2-84.1), Lenke type 3 curve (β = 77.9, P = 0.001, 95% CI 31.7-174), male sex (β=62.5, P=0.003, 95% CI 21.5-103), the Cobb angle (β=1.04, P=0.045, 95% CI 0.02-2.1), and the surgeon (β = 75.2, P < 0.0001, 95% CI 40-110) as independently associated with the length of surgery. The most significant factor associated with operative duration was the surgeon performing the case. We identified male sex, number of screws used, Lenke type 3 curves, osteotomy use, Cobb angle, and the surgeon variable as significantly associated with increased length of surgery in posterior arthrodesis of AIS patients.

Intraoperative Cone Beam–Computed Tomography With Navigation (O-ARM) Versus Conventional Fluoroscopy (C-ARM)

Cadaveric laboratory study. To compare the accuracy, efficiency, and safety of intraoperative cone beam-computed tomography with navigation (O-ARM) with traditional intraoperative fluoroscopy (C-ARM) for the placement of pedicle screws. Radiation exposure remains a concern with traditional methods of intraoperative imaging in spine surgery. The use of O-ARM has been proposed for more accurate and efficient spinal instrumentation. Understanding radiation imparted to patients and surgeons by O-ARM is important for assessing risks and benefits of this technology, especially in light of evolving indications. Four surgeons placed 160 pedicle screws on 8 cadavers without deformity. Eighty pedicle screws were placed using O-ARM and C-ARM each. Instrumentation was placed bilaterally in the thoracic (T1-T6) spine and lumbosacral junction (L5-S1) using a standard open technique, whereas minimally invasive surgery technique was used at the lumbar 3 to 4 (L3-L4) level. A "postoperative" computed tomography (CT) scan was performed on cadavers where instrumentation was done using the C-ARM. An independent musculoskeletal radiologist assessed final images for screw position. Time required to set up and instrumentation was recorded. Dosimeters were placed on multiple aspects of cadavers and surgeons to record radiation exposure. There were no differences in breach rate between the O-ARM and C-ARM groups (5 vs. 7, χ= 0.63, P = 0.4). The setup time for the O-ARM group was longer than that for the C-ARM group (592 vs. 297 s, P < 0.05). However, the average total time was statistically the same (1629 vs. 1639 s, P = 0.96). Radiation exposure was higher for surgeons in the C-ARM group and cadavers in the O-ARM group. When a "postoperative" CT scan was included in the estimation of the total radiation exposure, there was less of difference between the groups, but still more for the O-ARM group. In cadavers without deformity, O-ARM use results in similar breach rates as C-ARM for the placement of pedicle screws. Time for instrumentation is shorter with the O-ARM, but requires a longer setup time. The O-ARM exposes less radiation to the surgeon, but higher doses to the cadaver. N/A.

Radiation Exposure to the Spine Surgeon in Lumbar and Thoracolumbar Fusions With the Use of an Intraoperative Computed Tomographic 3-Dimensional Imaging System

A prospective clinical research article. The primary goals were to determine (1) radiation exposure to the spine surgeon with the use of an intraoperative 3-dimensional imaging system and (2) to define the safe distance from the computed tomographic scanner. Intraoperative radiation exposure to the spinal surgeon has been assessed during 2-dimensional fluoroscopy but has not been investigated during intraoperative 3-dimensional imaging. Ten patients undergoing lumbar or thoracolumbar fusion were enrolled in a prospective trial to determine the radiation exposure to a spine surgeon standing in the substerile room, with the use of the O-ARM Imaging System (Medtronic, Memphis, TN). A thermolucent digital dosimeter was worn at chest level without a lead apron. Dosimeter readings and distance from the spine surgeon were recorded. RESULTS.: Average surgeon exposure was 44.22 ± 17.4 μrem (range: 17.71-70.76 μrem). The mean distance from the O-ARM was 4.56 ± .32 m, and the surgeon was exposed for an average of 19.6 ± 5.7 seconds (range: 8.05-28.7 s). The annual number of necessary procedures required to surpass the exposure limit, according to the data presented here, would be 113,071 operations using O-ARM. Hence, the number of necessary procedures for O-ARM use is predicted to be 1,130,710 annual procedures to reach the occupational exposure limits for extremity, skin, and all other organs and 339,213 procedures to reach the limits for the lens of eye. Radiation exposure is minimal to the surgical team during routine use of the O-ARM imaging system. The number of procedures required to surpass occupational exposure limits is high if using appropriate distance from the O-ARM.

Optimization of Radiation Exposure and Image Quality of the Cone-beam O-arm Intraoperative Imaging System in Spinal Surgery

Retrospective study. To optimize the radiation doses and image quality for the cone-beam O-arm surgical imaging system in spinal surgery. Neurovascular compromise has been reported after screw misplacement during thoracic pedicle screw insertion. The use of O-arm with or without navigation system during spinal surgery has been shown to lower the rate of screw misplacement. The main drawback of such imaging surgical systems is the high radiation exposure. Chest phantom and cadaveric pig spine were examined on the O-arm with different scan settings: 2 were recommended by the O-arm manufacturer (120 kV/320 mAs, and 120 kV/128 mAs), and 3 low-dose settings (80 kV/80 mAs, 80 kV/40 mAs, and 60 kV/40 mAs). The radiation doses were estimated by Monte Carlo calculations. Objective evaluation of image quality included interobserver agreement in the measurement of pedicular width in chest phantom and assessment of screw placement in cadaveric pig spine. The effective dose/cm for 120 kV/320 mAs scan was 13, 26, and 69 times higher than those delivered with 80 kV/80 mAs, 80 kV/40 mAs, and 60 kV/40 mAs scans, respectively. Images with 60 kV/40 mAs were unreliable. Images with 80 kV/80 mAs were considered reliable with good interobserver agreement when measuring the pedicular width (random error 0.38 mm and intraclass correlation coefficient 0.979) and almost perfect agreement when evaluating the screw placement (κ value 0.86). The radiation doses of the O-arm system can be reduced 5 to 13 times without negative impact on image quality with regard to information required for spinal surgery.