O-arm Group Research Articles

Comparison of intraoperative O-arm- and conventional fluoroscopy (C-arm)-assisted insertion of pedicle screws in the treatment of fracture of thoracic vertebrae

Purpose:To introduce the intraoperative O-arm-assisted pedicle screw insertion without any navigation system in the treatment of thoracic vertebrae fracture and compare it to conventional fluoroscopy (C-arm)-assisted pedicle screw insertion technique.Methods:About 156 pedicle screws were inserted in 23 patients (C-arm group), and 208 pedicle screws were inserted in 30 patients (O-arm group). The postoperative computed tomography images were analyzed for pedicle violation based on Gertzbein classification. The total surgery time, the average time required for inserting a screw, the mean action times of adjusting guide probe and pedicle screw, and the hospitalization time were compared in both groups, respectively. The American Spinal Injury Association (ASIA) was used for evaluating the health outcomes pre- and postoperatively.Results:There are the higher accuracy rate of satisfactory pedicle screw placement (grades 0 and 1) and the less incidence of medial perforation in the O-arm group compared to the C-arm group ( p < 0.05). The average time required for inserting a screw, the action times of adjusting the guide probe and pedicle screw, and the hospitalization time in the O-arm group are less than the respective ones in the C-arm group ( p < 0.05). There was no significant difference for the total surgery time between both groups. No further damage of the nerve function postoperatively is found according to the ASIA grade.Conclusion:The O-arm-assisted pedicle screw insertion without navigation we described provides higher accuracy of pedicle screw placement and better clinical efficacy compared to conventional fluoroscopy (C-arm) technique.

Usefulness of navigated O-arm(®) in a teaching center for spinal trauma.

Background:There is a relatively high incidence of screw misplacement during spinal instrumentation due to distortion of normal anatomy following spinal trauma.Aims and Objectives:To evaluate and share the initial experience with the use of neuro-navigated 3D O-arm® (Medtronic, USA) as compared to traditional 2D fluoroscopy in atrauma center in India.Materials and Methods:In this retrospective study, consecutive patients of spinal injury who underwent screw fixation under O-arm guidance over nine-month period (July 2010 till March 2011) were evaluated for accuracy of screw placement. An equal number of consecutive patients prior to March 2011 who underwent screw fixation in 2D fluoroscopy were included for comparison. Patient demographics and radiology were reviewed and spinal injury was assessed using the ASIA grading in both the groups. Screw placement was assessed by postoperative CT scans of the relevant spine and accuracy of screw placement and breach of the medial or lateral cortex of the pedicle were recorded for each case.Results:In the O-arm group, there were 57 patients in whom 210 screws were inserted. None of the patients had screw mal-placement. In 2D fluoroscopy group, 57 patients had 268 screws insertions. 10 (3.73%) screws were found to be malpositioned in the postoperative CT scans (8 in thoracic spine and 2 in odontoid fractures). The malposition rate was highly significant in 2D fluoroscopy thoracolumbar (P = 0.0015) subgroup. One patient had neurological deterioration and three patients required repositioning of the screws.Conclusion:In a teaching center with multiple surgeons, the O-arm® imaging ensures accurate placement of screws as compared to traditional 2D fluoroscopy.

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.

Use of a Mobile Intraoperative Computed Tomography Scanner for Navigation Registration During Laser Interstitial Thermal Therapy of Brain Tumors

In recent years laser interstitial thermal therapy (LITT) has become the ablative neurosurgical procedure of choice. Multiple methods for registration and laser fiber verification have been described, with each method requiring multiple steps and significant time expenditure. We evaluated the use of a commercially available mobile computed tomography (CT) scanner for stereotactic registration during LITT for brain tumors in an attempt to simplify the procedure and improve intraoperative awareness of laser position. This is a retrospective chart review comparing LITT of brain tumors in 23 patients undergoing a standard protocol requiring skull pins and transport of the patient to a CT suite to obtain a reference scan compared with 14 patients in whom the Medtronic O-arm was used intraoperatively for navigation registration and confirmation of laser position. Total ablation of the target was achieved in all patients with no surgical complications. Total surgery time was shorter for the O-arm group than for the standard protocol group, once experience was gained with bringing the O-arm in and out of the surgical field. Return from the magnetic resonance imaging suite to the operating roomfor repositioning of the laser was required for 1 patient in the standard protocol group, but for no patients in the O-arm group. Once experience was gained with using the O-arm, estimated surgical costs were lower for this group. Use of a mobile intraoperative CT scanner for navigation registration and confirmation of laser position during LITT may play a role in streamlining the procedure and improving patient safety and comfort.

Does intraoperative navigation improve the accuracy of pedicle screw placement in the apical region of dystrophic scoliosis secondary to neurofibromatosis type I: comparison between O-arm navigation and free-hand technique.

To assess the accuracy of O-arm-navigation-based pedicle screw insertion in dystrophic scoliosis secondary to NF-1 and compare it with free-hand pedicle screw insertion technique. 32 patients with dystrophic NF-1-associated scoliosis were divided into two groups. A total of 92 pedicle screws were implanted in apical region (two vertebrae above and below the apex each) in 13 patients using O-arm-based navigation (O-arm group), and 121 screws were implanted in 19 patients using free-hand technique (free-hand group). The postoperative CT images were reviewed and analyzed for pedicle violation. The screw penetration was divided into four grades: grade 0 (ideal placement), grade 1 (penetration <2mm), grade 2 (penetration between 2 and 4mm), and grade 3 (penetration >4mm). The accuracy rate of pedicle screw placement (grade 0, 1) was significantly higher in the O-arm group (79%, 73/92) compared to 67% (81/121) of the free-hand group (P=0.045). Meanwhile, a significantly lower prevalence of grade 2-3 perforation was observed in the O-arm group (21 vs. 33%, P<0.05), and the incidence of medial perforation was significantly minimized by using O-arm navigation compared to free-hand technique (2 vs. 15%, P<0.01). Moreover, the implant density in apical region was significantly elevated by using O-arm navigation (58 vs. 42%, P<0.001). We reported 79% accuracy of O-arm-based pedicle screw placement in dystrophic NF-1-associated scoliosis. O-arm navigation system does facilitate pedicle screw insertion in dystrophic NF-1-associated scoliosis, demonstrating superiorities in the safety and accuracy of pedicle screw placement in comparison with free-hand technique.

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.

Incidence of and risk factors for superior facet violation in minimally invasive versus open pedicle screw placement during transforaminal lumbar interbody fusion: a comparative analysis

A reported risk factor for adjacent-segment disease is injury to the superior facet joint from pedicle screw placement. Given that the facet joint is not typically visualized during percutaneous pedicle screw insertion, there is a concern for increased facet violation (FV) in minimally invasive fusion procedures. The purpose of this study was to analyze and compare the incidence of FV among patients undergoing minimally invasive transforaminal lumbar interbody fusion (MITLIF) and open transforaminal lumbar interbody fusion (TLIF). The impact of O-arm navigation compared with traditional fluoroscopy on FV in MITLIF is also assessed, as are risk factors for FV. The authors identified a consecutive population of patients who underwent MITLIF with percutaneous pedicle screw placement, as well as a matched cohort of patients who underwent open TLIF. Postoperative CT imaging was assessed to determine intraarticular FV due to pedicle screw placement. Patients were stratified into minimally invasive and open TLIF groups. Within the MITLIF group, the authors performed a subanalysis of image guidance methods used in cases of FV. Two-tailed Student t-test, ANOVA, chi-square testing, and logistic regression were used for statistical analysis. A total of 282 patients were identified, with a total of 564 superior pedicle screw placements. The MITLIF group consisted of 142 patients with 284 screw insertions. The open TLIF group consisted of 140 patients with 280 screw insertions. Overall, 21 (7.4%) of 282 patients experienced FV. A total of 21 screws violated a facet joint for a screw-based FV rate of 3.7% (21 of 564 screws). There were no significant differences between the MITLIF and open TLIF groups in the percentage of patients with FV (6.3% vs 8.6%) and or the percentage of screws with FV (3.2% vs 4.3%) (p = 0.475 and p = 0.484, respectively). Further stratifying the MI group into O-arm navigation and fluoroscopic guidance subgroups, the patient-based rates of FV were 10.8% (4 of 37 patients) and 4.8% (5 of 105 patients), respectively, and the screw-based rates of FV were 5.4% (4 of 74 screws) and 2.4% (5 of 210 screws), respectively. There was no significant difference between the subgroups with respect to patient-based or screw-based FV rates (p = 0.375 and p = 0.442, respectively). The O-arm group had a significantly higher body mass index (BMI) (p = 0.021). BMI greater than 29.9 was independently associated with higher FV (OR 2.36, 95% CI 1.65-8.53, p = 0.039). The findings suggest that minimally invasive pedicle screw placement is not associated with higher rates of FV. Overall violation rates were similar in MITLIF and open TLIF. Higher BMI, however, was a risk factor for increased FV. The use of O-arm fluoroscopy with computer-assisted guidance did not significantly decrease the rate of FV.

Clinical Assessment of Percutaneous Lumbar Pedicle Screw Placement Using the O-Arm Multidimensional Surgical Imaging System

Increasing popularity of minimally invasive surgery for lumbar fusion has led to dependence upon intraoperative fluoroscopy for pedicle screw placement, because limited muscle dissection does not expose the bony anatomy necessary for traditional, freehand techniques nor for registration steps in image-guidance techniques. This has raised concerns about cumulative radiation exposure for both surgeon and operating room staff. The recent introduction of the O-arm Multidimensional Surgical Imaging System allows for percutaneous placement of pedicle screws, but there is limited clinical experience with the technique and data examining its accuracy. We present the first large clinical series of percutaneous screw placement using navigation of O-arm imaging and compare the results with the fluoroscopy-guided method. A retrospective review of a 24-month period identified patients undergoing minimally invasive lumbar interbody fusion. The O-arm was introduced in the middle of this period and was used for all subsequent patients. Accuracy of screw placement was assessed by examination of axial computed tomography or O-arm scans. The fluoroscopy group included 141 screws in 42 patients, and the O-arm group included 205 screws in 52 patients. The perforation rate was 12.8% in the fluoroscopy group and 3% in the O-arm group (P < .001). Single-level O-arm procedures took a mean 200 (153-241) minutes, whereas fluoroscopy took 221 (178-302) minutes (P < .03). Percutaneous pedicle screw placement with the O-arm Multidimensional Intraoperative Imaging System is a safe and effective technique and provided improved overall accuracy and reduced operative time compared with conventional fluoroscopic techniques.

Computer tomography assessment of pedicle screw placement in lumbar and sacral spine: comparison between free-hand and O-arm based navigation techniques

Transpedicular screw fixation has been accepted worldwide since Harrington et al. first placed pedicle screws through the isthmus. In vivo and in vitro studies indicated that pedicle screw insertion accuracy could be significantly improved with image-assisted systems compared with conventional approaches. The O-arm is a new generation intraoperative imaging system designed without compromise to address the needs of a modern OR like no other system currently available. The aim of our study was to check the accuracy of O-arm based and S7-navigated pedicle screw implants in comparison to free-hand technique described by Roy-Camille at the lumbar and sacral spine using CT scans. The material of this study was divided into two groups, free-hand group (group I) (30 patients; 152 screws) and O-arm group (37 patients; 187 screws). The patients were operated upon from January to September 2009. Screw implantation was performed during PLIF or TLIF mainly for spondylolisthesis, osteochondritis and post-laminectomy syndrome. The accuracy rate in our work was 94.1% in the free-hand group compared to 99% in the O-arm navigated group. Thus it was concluded that free-hand technique will only be safe and accurate when it is in the hands of an experienced surgeon and the accuracy of screw placement with O-arm can reach 100%.