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Background: Intraoperative 3D imaging using cone-beam CT (CBCT) provides improved assessment of implant position and reduction in spine surgery, is used for navigated surgical techniques, and therefore leads to improved quality of care. However, in some cases the image quality is not sufficient to correctly assess pedicle screw position and reduction, especially due to metal artifacts. The aim of this study was to investigate whether changing the acquisition trajectory of the CBCT in relation to the pedicle screw position during dorsal instrumentation of the spine can reduce metal artifacts and consequently improve image quality as well as clinical assessability on the artificial bone model., Methods: An artificial bone model was instrumented with pedicle screws in the thoracic and lumbar spine region (Th10 to L5). Then, the acquisition trajectory of the CBCT (Cios Spin, Siemens, Germany) to the pedicle screws was systematically changed in 5° steps in angulation (- 30° to + 30°) and swivel (- 30° to + 30°). Subsequently, radiological evaluation was performed by three blinded, qualified raters on image quality using 9 questions (including anatomical structures, implant position, appearance of artifacts) with a score (1-5 points). For statistical evaluation, the image quality of the different acquisition trajectories was compared to the standard acquisition trajectory and checked for significant differences., Results: The angulated acquisition trajectory increased the score for subjective image quality (p < 0.001) as well as the clinical assessability of pedicle screw position (p < 0.001) highly significant with particularly strong effects on subjective image quality in the vertebral pedicle region (d = 1.06). Swivel of the acquisition trajectory significantly improved all queried domains of subjective image quality (p < 0.001) as well as clinical assessability of pedicle screw position (p < 0.001). The data show that maximizing the angulation or swivel angle toward 30° provides the best tested subjective image quality. Angulation and swivel of the acquisition trajectory result in a clinically relevant improvement in image quality in intraoperative 3D imaging (CBCT) during dorsal instrumentation of the spine., (© 2023. The Author(s).)

Computer-assisted procedures are becoming increasingly more relevant in orthopedics and trauma surgery. The data situation on these systems has improved in recent years but still has a low level of evidence. In particular, data on short-term or medium-term results on the use of these procedures are currently available. These could show that improved precision and reproducibility of the surgical procedures can be achieved by the use of computer-assisted procedures. Nevertheless, there is still no recommendation in the current guidelines for routine use., (© 2023. The Author(s), under exclusive licence to Springer Medizin Verlag GmbH, ein Teil von Springer Nature.)

Background: Intraoperative cone beam CT (CBCT) imaging in dorsal instrumentation facilitates pedicle screw positioning. However, in patients with obesity, the benefit may be reduced due to artifacts that affect image quality. The purpose of this study was to evaluate whether intraoperative CBCT leads to an improved postoperative screw position compared to conventional fluoroscopy independent of body weight., Methods: A total of 71 patients (18 patients with a BMI > 30 kg/m 2 , 53 patients with a BMI < 30 kg/m 2 ) who underwent dorsal instrumentation with intraoperative CBCT imaging were included in study groups one (SG1) and two (SG2). Two control groups (CG1 and CG2) were randomly sampled to include 22 patients with a BMI > 30 kg/m 2 and 60 patients with a BMI < 30 kg/m 2 who underwent dorsal instrumentation without intraoperative CBCT imaging. The pedicle screw position in postoperative computed tomography was assessed using the Gertzbein-Robbins classification., Results: In SG1 (BMI > 30 kg/m 2 ), a total of 107 (83.6%) pedicle screws showed no relevant perforation (type A + B), and 21 (16.4%) pedicle screws showed relevant perforation (type C - E). In SG2 (BMI < 30 kg/m 2 ), 328 (90.9%) screws were classified as type A + B, and 33 (9.1%) screws were classified as type C - E. In CG1 (BMI > 30 kg/m 2 ), 102 (76.1%) pedicle screws showed no relevant perforation (type A + B), and 32 (23.9%) pedicle screws showed relevant perforation (type C - E). In CG2 (BMI < 30 kg/m 2 ), 279 (76.9%) screws were classified as type A + B, and 84 (23.1%) screws were classified as type C - E. There were significant differences between the values of SG1 and SG2 (p = 0.03) and between the values of SG2 and CG2 (p < 0.0001)., Conclusion: CBCT imaging in dorsal instrumentation can lead to an improved pedicle screw position among both patients with obesity and normal-weight patients. However, patients with obesity showed significantly worse pedicle screw positions postoperatively after dorsal instrumentation with intraoperative CBCT imaging than normal-weight patients., (© 2022. The Author(s).)

Background and Objectives : Navigated pedicle screw placement is becoming increasingly popular, as it has been shown to reduce the rate of screw misplacement. We present our intraoperative workflow and initial experience in terms of safety, efficiency, and clinical feasibility with a novel system for a 3D C-arm cone beam computed-tomography-based navigation of thoracolumbar pedicle screws. Materials and Methods : The first 20 consecutive cases of C-arm cone beam computed-tomography-based percutaneous pedicle screw placement using a novel navigation system were included in this study. Procedural data including screw placement time and patient radiation dose were prospectively collected. Final pedicle screw accuracy was assessed using the Gertzbein-Robbins grading system. Results : In total, 156 screws were placed. The screw accuracy was 94.9%. All the pedicle breaches occurred on the lateral pedicle wall, and none caused clinical complications. On average, a time of 2:42 min was required to place a screw. The mean intraoperative patient radiation exposure was 7.46 mSv. Conclusions : In summary, the investigated combination of C-arm CBCT-based navigation proved to be easy to implement and highly reliable. It facilitates the accurate and efficient percutaneous placement of pedicle screws in the thoracolumbar spine. The careful use of intraoperative imaging maintains the intraoperative radiation exposure to the patient at a moderate level.

Background: When using mobile 3D C-arms, impairments in image quality occur due to artefacts caused by metal implants as well as to the limited field of view. To avoid these restrictions, special computed tomography devices were designed, in order to improve image quality and to meet requirements for intraoperative usage., Objectives: To analyse practicability and benefits of a mobile intraoperative CT device (Airo, Brainlab, Munich, Germany) on the basis of several parameters that were obtained during a 40-month period., Materials and Methods: All procedures that were performed with usage of intraoperative CT between January 2017 and April 2020 were analysed with respect to anatomical region, count of scans, duration of scans, consequences drawn from the scans and use of navigation., Results: 354 CT-scans were performed in 171 patients (mean 2.07 [1 - 6] scans per procedure). 47.81% of the procedures were spinal, 52.19% affected the pelvis. 83% of the procedures were navigated. In 22% of patients, improvement in implant placement or reduction was achieved; in most patients (55%), a guidewire for pedicle screws was corrected. The mean scan duration was 10.33 s (3.54 - 21.72)., Conclusions: Use of intraoperative CT was reliable and helpful. Integration in OR standards requires more effort than mobile 3D C-arms. Image quality was outstanding for intraoperative conditions and allowed proper assessment of implant placement and reduction in all cases. Due to the high financial outlay of the system and the good image quality of 3D C-arms in the extremities, we assume that this procedure can be applied in intraoperative CT in traumatological cases in spinal and pelvic surgery in high-level trauma centres., Competing Interests: One of the authors received lecture fees from Brainlab AG./Einer der Autoren hat Vortragshonorare der Brainlab AG erhalten., (Thieme. All rights reserved.)

3D-navigated pedicle screw placement is increasingly performed as the accuracy has been shown to be considerably higher compared to fluoroscopy-guidance. While different imaging and navigation devices can be used, there are few studies comparing these under similar conditions. Thus, the objective of this study was to compare the accuracy of two combinations most used in the literature for spinal navigation and a recently approved combination of imaging device and navigation system. With each combination of imaging system and navigation interface, 160 navigated screws were placed percutaneously in spine levels T11-S1 in ten artificial spine models. 470 screws were included in the final evaluation. Two blinded observers classified screw placement according to the Gertzbein Robbins grading system. Grades A and B were considered acceptable and Grades C-E unacceptable. Weighted kappa was used to calculate reliability between the observers. Mean accuracy was 94.9% (149/157) for iCT/Curve, 97.5% (154/158) for C-arm CBCT/Pulse and 89.0% for CBCT/StealthStation (138/155). The differences between the different combinations were not statistically significant except for the comparison of C-arm CBCT/Pulse and CBCT/StealthStation (p = 0.003). Relevant perforations of the medial pedicle wall were only seen in the CBCT group. Weighted interrater reliability was found to be 0.896 for iCT, 0.424 for C-arm CBCT and 0.709 for CBCT. Under quasi-identical conditions, higher screw accuracy was achieved with the combinations iCT/Curve and C-arm CBCT/Pulse compared with CBCT/StealthStation. However, the exact reasons for the difference in accuracy remain unclear. Weighted interrater reliability for Gertzbein Robbins grading was moderate for C-arm CBCT, substantial for CBCT and almost perfect for iCT., (© 2022. The Author(s).)

Background: Correct positioning of pedicle screws can be challenging. Intraoperative imaging may be helpful. The purpose of this study was to evaluate the use of intraoperative 3D imaging with a cone-beam CT. The hypotheses were that intraoperative 3D imaging (1) will lead to an intraoperative revision of pedicle screws and (2) may diminish the rate of perforated screws on postoperative imaging., Methods: Totally, 351 patients (age 60.9 ± 20.3 a (15-96); m/f 203/148) underwent dorsal instrumentation with intraoperative 3D imaging with 2215 pedicle screws at a trauma center level one. This study first evaluates intraoperative imaging. After this, 501 screws in 73 patients (age 62.5 ± 19.7 a; m/f 47/26) of this collective were included in the study group (SG) and their postoperative computed tomography was evaluated with regard to screw position. Then, 500 screws in 82 patients (age 64.8 ± 14.4 a; m/f 51/31) as control group (CG), who received the screws with conventional 2D fluoroscopy but without 3D imaging, were evaluated with regard to screw position., Results: During the placement of the 2215 pedicle screws, 158 (7.0%) intraoperative revisions occurred as a result of 3D imaging. Postoperative computed tomography of the SG showed 445 (88.8%) screws without relevant perforation (type A + B), of which 410 (81.8%) could be classified as type A and 35 (7.0%) could be classified as type B. Fifty-six (11.2%) screws in SG showed relevant perforation (type C-E). In contrast, 384 (76.8%) screws in the CG were without relevant perforation (type A + B), of which 282 (56.4%) could be classified as type A and 102 (20.4%) as type B. One hundred and sixteen (23.2%) screws in the CG showed relevant perforation (type C-E)., Conclusion: This study shows that correct placement of pedicle screws in spine surgery with conventional 2D fluoroscopy is challenging. Misplacement of screws cannot always be prevented. Intraoperative 3D imaging with a CBCT can be helpful to detect and revise misplaced pedicle screws intraoperatively. The use of intraoperative 3D imaging will probably minimize the number of revision procedures due to perforating pedicle screws., (© 2021. The Author(s).)

Background: Intraoperative imaging is regularly used for intraoperative reduction control and evaluation of the implant position in trauma surgery. 2D imaging is limited, especially in complex anatomical regions such as the pelvis. The introduction of mobile 3D C-arms (CBCT: cone-beam computed tomography) has significantly improved intraoperative assessment. Nevertheless, there are still limitations regarding the field of view and metal artifacts. The purpose of this study was to evaluate the potential of intraoperative computed tomography (iCT) in surgical treatment of sacroiliac (SI) injuries., Methods: Twenty-five cases with injuries of the posterior pelvic ring involving the SI region that were surgically treated with navigated SI screws using the mobile iCT Airo (Brainlab, Munich, Germany) were analysed. Subsequently, the data were compared with historical control groups (CBCT with and without navigation; 2D fluoroscopy only)., Results: The average score for subjective image quality achieved using the Likert scale is significantly higher for the iCT (4.48 ± 0.65) than for the CBCT (3.04 ± 0.69) with p = 0.00. The average duration of surgery using iCT was 189.32 ± 88.64 min, which was not significantly different from the control groups (p = 0.14 - 0.70). The average fluoroscopy time using iCT was 81.96 ± 97.34 s, which was significantly shorter than in all of the control groups (p = 0.00 - 0.03). The rate for postoperatively detected complications after using iCT was 0% (n = 0). Compared with the 2D-only control group (25%; n = 1), there is a significant difference (p = 0.01). The remaining two control groups showed no significant differences (p = 0.09 - 0.19)., Conclusions: The iCT provides excellent image quality that allows reliable assessment of fracture reduction and implant placement even in complex anatomical regions. The radiation exposure for the medical staff is reduced by decreasing the fluoroscopy time without significantly prolonging the surgical time. Overall, the possibility of intraoperative correction improves clinical outcome and patient treatment in the long term., Competing Interests: Declaration of Competing Interest Holger Keil is a paid lecturer for the Brainlab AG (Munich, Germany). This cooperation influenced neither the outcome of the study nor the manuscript., (Copyright © 2020. Published by Elsevier Ltd.)

Background: This study evaluates image quality of a new flat-panel three-dimensional (3D) C-arm to the current generation and to intraoperative and stationary computed tomography (CT) in spinal surgery., Methods: Three-dimensional-imaging of 44 posterior screws acquired with two generations of 3D C-arms (Arcadis Orbic, AO and Cios Spin, CS, Siemens, Germany) and CT scans (mobile intraoperative CT Airo, iCT, Brainlab, Germany and stationary CT Aquilion 32, sCT, Toshiba, Japan) were performed. Evaluation regarded assessability and measurements of implant position., Results: Assessability score was 0.11 in AO, 0.56 in sCT, 0.91 in iCT and 1.46 in CS (p < 0.0005). AO and CS showed a significant difference in accuracy (p = 0.001) as well as CS and iCT (p < 0.001). Measurements of protrusion over the anterior edge did not show a significant difference (p = 0.341)., Conclusions: Image quality of the new generation of flat-panel 3D C-arms competes with CT imaging and offers significant advantages compared to the former generation., (© 2020 John Wiley & Sons Ltd.)

Background: Being a proven method in trauma and spine surgery, intraoperative 3D imaging (CBCT) has intrinsic deficits in difficult anatomy and with artifacts because of metal implants. The purpose of this study was to evaluate the use of intraoperative computed tomography (iCT) in acetabular surgery., Methods: Ten cases of acetabular fractures that were operated with intraoperative use of the mobile CT scanner Brainlab Airo were analyzed. Data were compared with a historical group of 17 patients., Results: Additional fluoroscopy time was 24.2 seconds (6-91), which was significantly lower than in the control group where it was 211.4 seconds (77-446; P < 0.000). Operation time did not differ significantly (iCT group 196.8 min [122-288], control group 240.8 min [71-411], P = 0.234)., Conclusion: iCT provides images of a reliable high quality and assessability. Radiation exposure to the staff is reduced while surgery time is not altered significantly. Quality of intraoperative imaging and thus patient care can substantially improve patient outcome., (© 2019 John Wiley & Sons, Ltd.)