Intraoperative cone beam-computed tomography with navigation (O-ARM) versus conventional fluoroscopy (C-ARM): a cadaveric study comparing accuracy, efficiency, and safety for spinal instrumentation

The Impact of Navigation in Lumbar Spine Surgery: A Study of Historical Aspects, Current Techniques and Future Directions

Background/Objectives: We sought to improve accuracy while minimizing radiation hazards, improving surgical outcomes, and preventing potential complications. Despite the increasing popularity of these systems, a limited number of papers have been published addressing the historical evolution, detailing the areas of use, and discussing the advantages and disadvantages, of this increasingly popular system in lumbar spine surgery. Our objective was to offer readers a concise overview of navigation system history in lumbar spine surgeries, the techniques involved, the advantages and disadvantages, and suggestions for future enhancements to the system. Methods: A comprehensive review of the literature was conducted, focusing on the development and implementation of navigation systems in lumbar spine surgeries. Our sources include PubMed-indexed peer-reviewed journals, clinical trial data, and case studies involving technologies such as computer-assisted surgery (CAS), image-guided surgery (IGS), and robotic-assisted systems. Results: To develop more practical, effective, and accurate navigation techniques for spine surgery, consistent advancements have been made over the past four decades. This technological progress began in the late 20th century and has since encompassed image-guided surgery, intraoperative imaging, advanced navigation combined with robotic assistance, and artificial intelligence. These technological advancements have significantly improved the accuracy of implant placement, reducing the risk of misplacement and related complications. Navigation has also been found to be particularly useful in tumor resection and minimally invasive surgery (MIS), where conventional anatomic landmarks are lacking or, in the case of MIS, not visible. Additionally, these innovations have led to shorter operative times, decreased radiation exposure for patients and surgical teams, and lower rates of reoperation. As navigation technology continues to evolve, future innovations are anticipated to further enhance the capabilities and accessibility of these systems, ultimately leading to improved patient outcomes in lumbar spine surgery. Conclusions: The initial limited utilization of navigation system in spine surgery has further expanded to encompass almost all fields of lumbar spine surgeries. As the cost-effectiveness and number of trained surgeons improve, a wider use of the system will be ensured so that the navigation system will be an indispensable tool in lumbar spine surgery. However, continued research and development, along with training programs for surgeons, are essential to fully realize the potential of these technologies in clinical practice.

Top 100 Most Cited Articles on Intraoperative Image-Guided Navigation in Spine Surgery

Navigation technologies have become essential in spine surgery over the last decade, offering precise procedures and minimizing risks. To the best of our knowledge, this is the first bibliometric analysis on this topic, providing insights and trends on topics, authors, and journals. The study identifies and analyzes the 100 most cited articles related to navigation in spine surgery. A systematic search was performed in Scopus and Google Scholar to identify all articles related to navigation in spine surgery (38,057 articles). The 100 most cited were analyzed for citations, titles, abstracts, authors, affiliations, keywords, country and institute of origin, year of publication, and level of evidence. The search was conducted in October 2023. The 100 most cited articles were published between 1995 and 2019, with 2010 to 2019 being the most prolific decade (46%). The most cited article had 733 citations, and the paper with the most citations per year averaged 59.27 citations/year. The Spine Journal had the most articles (34%). The United States contributed the most articles (39%). Most publications were clinical research and reviews (94%), with an overall evidence grade of IV-V (63%). A positive trend was noted in the last decade for incorporating augmented reality. This bibliometric analysis offers valuable insights and trends in spine surgery navigation literature. The findings indicate that technological advancements have led to more articles with higher levels of evidence. These pivotal articles shape evidence-based medicine, future surgeons, and industry improvements in navigated spine surgery.

Top 25 Most Cited Articles on Intraoperative Computer Tomography-Guided Navigation in Spine Surgery

BACKGROUND

In recent years, the use of intraoperative computer tomography-guided (CT-guided) navigation has gained significant popularity among health care providers who perform minimally invasive spine surgery. This review aims to identify and analyze trends in the literature related to the widespread adoption of CT-guided navigation in spine surgery, emphasizing the shift from conventional fluoroscopy-based techniques to CT-guided navigation.

METHODS

Articles pertaining to this study were identified via a database review and were hierarchically organized based on the number of citations. An "advanced document search" was performed on September 28th, 2022, utilizing Boolean search operator terms. The 25 most referenced articles were combined into a primary list after sorting results in descending order based on the total number of citations.

RESULTS

The "Top 25" list for intraoperative CT-guided navigation in spine surgery cumulatively received a total of 2742 citations, with an average of 12 new citations annually. The number of citations ranged from 246 for the most cited article to 60 for the 25th most cited article. The most cited article was a paper by Siewerdsen et al., with 246 total citations, averaging 15 new citations per year.

CONCLUSIONS

Intraoperative CT-guided navigation is 1 of many technological advances that is used to increase surgical accuracy, and it has become an increasingly popular alternative to conventional fluoroscopy-based techniques. Given the increasing adoption of intraoperative CT-guided navigation in spine surgery, this review provides impactful evidence for its utility in spine surgery.

Assessing Procedural Accuracy in Lateral Spine Surgery: A Retrospective Analysis of Percutaneous Pedicle Screw Placement with Intraoperative CT Navigation

Percutaneous pedicle screws (PPSs) are commonly used in posterior spinal fusion to treat spine conditions such as trauma, tumors, and degenerative diseases. Precise PPS placement is essential in preventing neurological complications and improving patient outcomes. Recent studies have suggested that intraoperative computed tomography (CT) navigation can reduce the dependence on extensive surgical expertise for achieving accurate PPS placement. However, more comprehensive documentation is needed regarding the procedural accuracy of lateral spine surgery (LSS). In this retrospective study, we investigated patients who underwent posterior instrumentation with PPSs in the thoracic to lumbar spine, utilizing an intraoperative CT navigation system, between April 2019 and September 2023. The system's methodology involved real-time CT-based guidance during PPS placement, ensuring precision. Our study included 170 patients (151 undergoing LLIF procedures and 19 trauma patients), resulting in 836 PPS placements. The overall PPS deviation rate, assessed using the Ravi scale, was 2.5%, with a notably higher incidence of deviations observed in the thoracic spine (7.4%) compared to the lumbar spine (1.9%). Interestingly, we found no statistically significant difference in screw deviation rates between upside and downside PPS placements. Regarding perioperative complications, three patients experienced issues related to intraoperative CT navigation. The observed higher rate of inaccuracies in the thoracic spine suggests that various factors may contribute to these differences in accuracy, including screw size and anatomical variations. Further research is required to refine PPS insertion techniques, particularly in the context of LSS. In conclusion, this retrospective study sheds light on the challenges associated with achieving precise PPS placement in the lateral decubitus position, with a significantly higher deviation rate observed in the thoracic spine compared to the lumbar spine. This study emphasizes the need for ongoing research to improve PPS insertion techniques, leading to enhanced patient outcomes in spine surgery.

Effect of O-arm on reduction quality and functional recovery of acetabular dome impaction fractures: a retrospective clinical study

BACKGROUND

Acetabular dome impaction fractures (ADIF) are difficult to reduce and have a high failure rate. Consistency between the acetabulum and the femoral head is usually assessed using intraoperative X-ray fluoroscopy to evaluate the quality of fracture reduction. This study examines the effects of intraoperative mobile 2D/3DX imaging system (O-arm) on the reduction quality and functional recovery of ADIF.

METHODS

We retrospectively analysed the data of 48 patients with ADIF treated at Honghui Hospital between October 2018 and October 2021.The patients were divided into the X-ray and O-arm groups. The residual step-off and gap displacements in the acetabular dome region were measured, and fracture reduction quality was evaluated. Hip function was evaluated using the modified Merle d'Aubigné and Postel scoring systems.

RESULTS

There were no significant intergroup differences in the preoperative general data (p > 0.05). The mean residual average step displacement in the acetabular dome region was 3.48 ± 2.43 mm and 1.61 ± 1.16 mm (p < 0.05), while the mean gap displacement was 6.72 ± 3.69 mm and 3.83 ± 1.67 mm (p < 0.05) in the X-ray and the O-arm groups, respectively. In the X-ray group, according to the fracture reduction criteria described by Verbeek and Moed et al., one case was excellent, 13 cases were good, 11 cases were poor; 56% were excellent or good. In the O-arm group, seven cases were excellent, 12 cases were good, and four cases were poor; overall in this group, 82.6% were excellent or good (p < 0.05). A total of 46 patients achieved fracture healing at the last follow-up. In the X-ray group, according to the modified Merle d'Aubigné and Postel function score, three cases were excellent,12 cases were good, six cases were middle, three cases were poor; 62.5% were excellent or good, In the O-arm group, 15 cases were excellent, four cases were good, two cases were middle, one case was poor; 86.4% were excellent or good (p < 0.05).

CONCLUSIONS

The application of O-arm in ADIF can improve fracture reduction quality and functional recovery.

Radiation exposure for pedicle screw placement with three different navigation system and imaging combinations in a sawbone model

BACKGROUND

Studies have shown that pedicle screw placement using navigation can potentially reduce radiation exposure of surgical personnel compared to conventional methods. Spinal navigation is based on an interaction of a navigation software and 3D imaging. The 3D image data can be acquired using different imaging modalities such as iCT and CBCT. These imaging modalities vary regarding acquisition technique and field of view. The current literature varies greatly in study design, in form of dose registration, as well as navigation systems and imaging modalities analyzed. Therefore, the aim of this study was a standardized comparison of three navigation and imaging system combinations in an experimental setting in an artificial spine model.

METHODS

In this experimental study dorsal instrumentation of the thoracolumbar spine was performed using three imaging/navigation system combinations. The system combinations applied were the iCT/Curve, cCBCT/Pulse and oCBCT/StealthStation. Referencing scans were obtained with each imaging modality and served as basis for the respective navigation system. In each group 10 artificial spine models received bilateral dorsal instrumentation from T11-S1. 2 referencing and control scans were acquired with the CBCTs, since their field of view could only depict up to five vertebrae in one scan. The field of view of the iCT enabled the depiction of T11-S1 in one scan. After instrumentation the region of interest was scanned again for evaluation of the screw position, therefore only one referencing and one control scan were obtained. Two dose meters were installed in a spine bed ventral of L1 and S1. The dose measurements in each location and in total were analyzed for each system combination. Time demand regarding screw placement was also assessed for all system combinations.

RESULTS

The mean radiation dose in the iCT group measured 1,6 ± 1,1 mGy. In the cCBCT group the mean was 3,6 ± 0,3 mGy and in the oCBCT group 10,3 ± 5,7 mGy were measured. The analysis of variance (ANOVA) showed a significant (p < 0.0001) difference between the three groups. The multiple comparisions by the Kruskall-Wallis test showed no significant difference for the comparison of iCT and cCBCT (p1 = 0,13). Significant differences were found for the direct comparison of iCT and oCBCT (p2 < 0,0001), as well as cCBCT and oCBCT (p3 = 0,02). Statistical analysis showed that significantly (iCT vs. oCBCT p = 0,0434; cCBCT vs. oCBCT p = 0,0083) less time was needed for oCBCT based navigated pedicle screw placement compared to the other system combinations (iCT vs. cCBCT p = 0,871).

CONCLUSION

Under standardized conditions oCBCT navigation demanded twice as much radiation as the cCBCT for the same number of scans, while the radiation exposure measured for the iCT and cCBCT for one scan was comparable. Yet, time effort was significantly less for oCBCT based navigation. However, for transferability into clinical practice additional studies should follow evaluating parameters regarding feasibility and clinical outcome under standardized conditions.

Computer-assisted Navigation in Lumbar Spine Instrumented Fusions: Comparison of In-hospital and 30-Day Postoperative Complications With Nonnavigated Fusions in a National Database

OBJECTIVE

To compare in-hospital and 30-day postoperative complications for lumbar spine operations with and without use of computer-assisted navigation.

METHODS

Patients who underwent 1-level to 3-level lumbar spinal instrumentation and fusions 2011 to 2014 were identified in the American College of Surgeons National Surgical Quality Improvement Program database. Emergent procedures and patients aged younger than 18 years were excluded. Patients whose surgery involved the use of computer-assisted navigation were propensity score matched 1:4 based on preoperative demographics and comorbidities to operations without the use of navigation. Multivariate analysis was done to compare postoperative complications.

RESULTS

In total, 8,500 patients (average age: 60.7 ± 12.9, male 3,866, female 4,634) were analyzed (1,700 navigation, 6,800 Non-Navigated). Operations with navigation had significantly fewer overall complications (24% vs. 27%, P = 0.008; odds ratio [OR] = 0.83; CI = 0.73 to 0.95), fewer minor complications (20% vs. 24%, P = 0.002; OR = 0.80; CI = 0.70 to 0.91), fewer blood transfusions (17% v. 20%, P = 0.013; OR = 0.82; CI = 0.71 to 0.95), more wound dehiscences (0.4% vs. 0.8%, P = 0.022; OR = 2.16; CI = 1.12,4.19), and shorter average lengths of hospital stays (4.8 ± 4.8 vs. 5.1 ± 5.8 days, P = 0.01). Operations with computer navigation had significantly longer average surgical times (247 ± 129 vs 221 ± 115 minutes, P < 0.001). No significant differences were observed in 30-day revision rates, readmissions, and mortality.

CONCLUSION

Although use of computer-assisted navigation in short-segment lumbar spine fusions (1 to 3 levels) did not decrease revision rates for screw misplacement within 30 days postoperatively, it independently reduced the frequency of blood transfusions and minor complications and decreased hospital lengths of stay compared with operations without navigation. These benefits came at the expense of increased surgical times and wound dehiscences within 30 days postoperatively. Given the inherent limitations of large national databases, these results warrant confirmation through prospective, multicenter investigations.

Fluoroscopy-Assisted Freehand Versus 3D-Navigated Imaging-Assisted Pedicle Screw Insertion: A Multicenter Study

INTRODUCTION

Pedicle screw placement is a widely accepted surgical procedure for spinal fixation. Despite increases in knowledge about and expertise in pedicle screw insertion techniques, overall reported screw misplacement rates are still high. Spinal neuronavigation and intraoperative computed tomography (CT) imaging improves the accuracy and safety of pedicle screw placement through the continuous monitoring of screw trajectory. The purpose of this study is to compare pedicle screw placement under an O-arm intraoperative imaging system assisted by the StealthStation navigation system with screw placement under conventional fluoroscopy (C-arm).

METHODS

For 222 patients, 1288 implanted pedicle screws in total were evaluated between 2018 and 2020. All patients underwent pedicle screw placement in the thoracic and lumbosacral regions through a posterior approach. Moreover, 107 patients (48.2%), 48 men and 59 women, underwent freehand screw placement under conventional fluoroscopy (C-arm group), whereas 115 patients (51.8%), 53 men and 62 women, underwent pedicle screw insertion under O-arm guidance with the help of the StealthStation neuronavigation system (Medtronic Navigation, Louisville, CO, USA) (O-arm group). Data were recorded and retrospectively analyzed. The accuracy of pedicle screw placement was postoperatively examined by using CT imaging and analyzed according to the Gertzbein-Robbins classification.

RESULTS

Of the 1288 pedicle screws, 665 (51.6%) were placed with C-arm image-guided assistance with a mean of 6.21 ± 2.1 screws per patient and 643 (48.4%) with O-arm image-guided assistance with a mean of 5.59 ± 1.6 screws. The average time for the screw placement procedure was 3:57 ± 1:07 h in the C-arm group and 4:21 ± 1:41 h in the O-arm group. A correct screw placement was detected in 92.78% of patients in the C-arm group and in 98.13% of patients in the O-arm group. Medial cortical breach was shown in 13 Grade B screws (1.95%), 19 Grade C (2.86%), 14 Grade D (2.11%), and two Grade E (0.3%) in the C-arm group, whereas this was shown in 11 Grade B screws (1.71%) and one Grade C (0.16%) in the O-arm group. Lateral breach occurred in eight screws in both groups. Anterior vertebral body breach was shown in eight screws in the C-arm group, whereas it was shown in four screws in the O-arm group. Reoperation for screw misplacement was mandatory in five patients in the C-arm group and two patients in the O-arm group.

CONCLUSION

Pedicle screw placement under an O-arm intraoperative imaging system assisted by spinal navigation showed greater accuracy compared with placement under conventional fluoroscopic control, thus avoiding the onset of major postoperative complications. Notably, a reduction in medial and anterior breaches has been demonstrated.

Perpendicular probing and screwing technique: A simple method for accurate pedicle screw placement based on the human internal reference frame for angle estimation

The pedicle screw (PS) is widely used for spinal fixation surgery. However, PS malpositioning can cause critical complications; thus, the accuracy of ascertaining PS trajectory is paramount. This study aimed to demonstrate the accuracy and safety of a simple and cost-effective PS placement technique using a human internal reference frame for angle estimation. Ex vivo lumbar porcine spine samples were fixed to a wooden board with rostrocaudal and mediolateral rotational angles adjusted by two angle vises. PS entry points (EPs) were identified using clear anatomical vertebral landmarks. PS placement was performed on one side using the perpendicular probing and screwing technique (PPST), wherein the attitude angle of the sample was adjusted such that the longitudinal axis of the target pedicle was perpendicular to the ground. The pedicle probe and PS driver were manually maintained perpendicular to the ground during probing and PS placement. PS placement on the contralateral side was performed freehand as a control. Offsets between the preoperatively planned and implanted PS rotational angles measured using computed tomography for PPST and freehand method were analyzed. Pedicle wall penetration was also evaluated. The mean ± standard error of the medial rotational offsets was 5.83° ± 0.57° in the freehand group versus 2.89° ± 0.31° in the PPST group (p <0.001), and the rostrocaudal rotational offsets were 4.81° ± 0.65° in the freehand group versus 2.92° ± 0.45° in the PPST group (p = 0.01). The mean pedicle wall penetration distance was significantly reduced by PPST (0.28 ± 0.12 mm vs 0.80 ± 0.17 mm in the freehand group, p = 0.0071). Thus, PPST improved PS positioning accuracy, resulting in reduced pedicle wall penetration and increased PS placement safety. This simple technique is also potentially cost-effective for institutions without computer-assisted surgical systems.

Microsurgical Tubular Resection of Intradural Extramedullary Spinal Tumors With 3-Dimensional-Navigated Localization

BACKGROUND

The safety and efficacy of minimally invasive spine surgical (MISS) approaches have stimulated interest in adapting MISS principles for more complex pathology including intradural extramedullary (IDEM) tumors. No study has characterized a repeatable approach integrating the MISS surgical technique and 3-dimensional intraoperative navigated localization for the treatment of IDEM tumors.

OBJECTIVE

To describe a safe and reproducible technical guide for the navigated MISS technique for the treatment of benign intradural and extradural spinal tumors.

METHODS

Retrospective review of prospectively collected data on 20 patients who underwent navigated microsurgical tubular resection of intradural extramedullary tumors over a 5-year period. We review our approach to patient selection and report demographic and outcomes data for the cohort.

RESULTS

Our experience demonstrates technical feasibility and safety with a 100% rate of gross total resection with no patients demonstrating recurrence during an average follow-up of 20.2 months and no instances of perioperative complications. We demonstrate favorable outcomes regarding blood loss, operative duration, and hospital length of stay.

CONCLUSION

Navigated localization and microsurgical tubular resection of IDEM tumors is safe and effective. Adherence to MISS principles and thoughtful patient selection facilitate successful management of these patients.

First Clinical Experience with a Novel 3D C-Arm-Based System for Navigated Percutaneous Thoracolumbar Pedicle Screw Placement

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.

Cone-Beam Navigation Can Reduce the Radiation Exposure and Save Fusion Length-Dependent Operation Time in Comparison to Conventional Fluoroscopy in Pedicle-Screw-Based Lumbar Interbody Fusion

This study investigates the advantages and disadvantages of cone-beam-based navigated standardized posterior lumbar interbody fusion surgery (PLIF), regarding the radiation exposure and perioperative time management, compared to the use of fluoroscopy. Patients treated receiving an elective one- to three-level PLIF were retrospectively enrolled in the study. The surgery time, preparation time, operation room time, and effective dose (mSv) were analyzed for comparison of the radiation exposure and time consumption between cone-beam and fluoroscopy; Results: 214 patients were included (108 cone-beam navigated, and 106 traditional fluoroscopies). Using cone-beam navigation, reductions in the effective dose (2.23 ± 1.96 mSv vs. 3.39 ± 2.32 mSv, p = 0.002) and mean surgery time of 30 min (143.62 ± 43.87 min vs. 171.10 ± 48.91 min, p < 0.001) were demonstrated, which leveled out the extended preparation time of 7−8 min (37.25 ± 9.99 min vs. 29.65 ± 7.69 min, p < 0.001). These effects were fusion length dependent and demonstrated additional benefits in multisegmental surgeries. The cone-beam navigation system led to a reduction in the perioperative time requirements and radiation exposure. Furthermore, the controversially discussed longer preparation time when using cone-beam navigation was amortized by a shortened surgery time, especially in multilevel surgery.

Transpedicular Screw Placement Accuracy Using the O-Arm Versus Freehand Technique at a Single Institution

STUDY DESIGN

Retrospective cohort.

OBJECTIVE

The objective of this study was to assess the effectiveness of the O-arm as an intraoperative imaging tool by comparing accuracy of pedicle screw placement to freehand technique.

METHODS

The study comprised a total of 1161 screws placed within the cervical (n = 187) thoracic (n = 657), or lumbar (n = 317) spinal level. A pedicle breach was determined by any measurable displacement of the screw outside of the pedicle cortex in any plane on postoperative images. Each pedicle screw was subsequently classified by its placement relative to the targeted pedicle. Statistical analysis was then performed to determine the frequency and type of pedicle screw mispositioning that occurred using the O-arm versus freehand technique.

RESULTS

A total of 155 cases (O-arm 84, freehand 71) involved the placement of 454 pedicle screws in the O-arm group and 707 pedicle screws in the freehand group. A pedicle breach occurred in 89 (12.6%) screws in the freehand group and 55 (12.1%) in the O-arm group (P = .811). Spinal level operated upon did not influence pedicle screw accuracy between groups (P > .05). Three screws required revision surgery between the 2 groups (O-arm 1, freehand 2, P > .05). The most frequent breach type was a lateral pedicle breach (O-arm 22/454, 4.8%; freehand 54/707, 7.6%), without a significant difference between groups (P > .05).

CONCLUSIONS

The use of the O-arm coupled with navigation does not assure improved transpedicular screw placement accuracy when compared with the freehand technique.

O-Arm Assisted Cervicothoracic Spine Pedicle Screw Placement Accuracy Is Higher Than C-Arm Fluoroscopy

OBJECTIVE

We compared the accuracy of C-arm fluoroscopy versus O-arm-assisted pedicle screw (PS) placement in the cervicothoracic spinal junction (CTSJ).

METHODS

Patients who underwent PS placement in the CTSJ (C7-T4) at our hospital were included in this study. Of 37 patients who underwent PS placement in the CTSJ, 20 underwent intraoperative C-arm fluoroscopy-assisted surgery (C Group) and 17 underwent intraoperative O-arm-assisted surgery (O Group). In total, 159 PSs were placed-73 in the C Group and 86 in the O Group. The accuracy of PS placement was compared between the C Group and O Group using the classification proposed by Gertzbein and Robbins to analyze pedicle violation.

RESULTS

PS accuracy was higher in the O Group than C Group; PS placement evaluated as grade A, representing no perforation, was 95.3% (82/86) for the O Group, whereas it was 78.1% (57/73) for the C Group. There was a clear statistically significant difference in accuracy of PS placement between the groups (P = 0.0013).

CONCLUSIONS

O-arm-assisted surgery improved the accuracy of PS placement in the CTSJ.

Minimally Invasive Resection of an S3 Osteoid Osteoma Using an Intraoperative O-Arm: A Technical Note

Osteoid osteomas are benign primary bone tumors that typically arise in posterior vertebrae of the spine. For patients with severe pain or those poorly controlled with non-steroidal anti-inflammatory drugs, surgical management is the mainstay of treatment. The recommended surgical treatment option is complete open excision, although minimally invasive CT-guided percutaneous excision and CT-guided radiofrequency ablation have been reported. Open resection can result in prolonged hospital stays, activity restrictions, and possible spinal destabilization. We sought to utilize a lateral minimally invasive approach. We highlight the importance of aggressive surgical resection and the utility of using fluoroscopy and O-arm guidance to optimize the extent of resection. We report a pediatric case of a 12-year-old male who presented with an S3 osteoid osteoma. The patient underwent a minimally invasive resection with complete resection and confirmation of the histopathologic diagnosis. Postoperative imaging showed complete resection of the tumor. The patient went home five hours after surgery with return to daily activities; his symptoms resolved completely. However, the patient had symptomatic recurrence and underwent a second more aggressive minimally invasive resection using O-arm guidance. At the current three-month follow-up, the patient is symptom- and tumor-free. The minimally invasive resection of a pediatric sacral osteoid osteoma is a valid alternative to standard open resection and is associated with a decreased blood loss, decreased length of stay in the hospital, and decreased time to full functional recovery. The pitfalls are learning curve and risk of incomplete resection that can be counterbalanced with an intraoperative O-arm to guide resection and confirm complete excision.

The Intraoperative Use of a Portable Cone-Beam Computed Tomography System for the Diagnosis of Intraperitoneal Bladder Perforation

Background

Intraoperative imaging for endourologic procedures is generally limited to single-plane fluoroscopic X-ray. The O-arm™ is a mobile cone-bean CT scanner that may have applications in urologic surgeries. Case Presentation. We present a case of an 85-year-old male with radiation cystitis and recurrent gross hematuria who was identified to have a bladder perforation on cystoscopy during emergent clot evacuation. Single-view fluoroscopic evaluation was inconclusive as to whether an intraperitoneal bladder perforation occurred. A portable cone-beam CT scan was used to acquire a 3-D CT cystogram, which demonstrated intraperitoneal contrast extravasation, confirming the diagnosis of an intraperitoneal bladder perforation.

Conclusion

We report the first use of a portable cone-beam CT scanner to perform an intraoperative CT cystogram to diagnose an intraperitoneal bladder perforation and guide surgical management.

Surgivisio® and O-arm®O2 cone beam CT mobile systems for guidance of lumbar spine surgery: Comparison of patient radiation dose

PURPOSE

To compare patient radiation doses in cone beam computed tomography (CBCT) of two mobile systems used for navigation-assisted mini-invasive orthopedic surgery: O-arm®O2 and Surgivisio®.

METHODS

The study focused on imaging of the spine. Thermoluminescent dosimeters were used to measure organs and effective doses (ED) during CBCT. An ionization-chamber and a solid-state sensor were used to measure the incident air-kerma (K_i) at the center of the CBCT field-of-view and K_i during 2D-imaging, respectively. The PCXMC software was used to calculate patient ED in 2D and CBCT configurations. The image quality in CBCT was evaluated with the CATPHAN phantom.

RESULTS

The experimental ED estimate for the low-dose 3D-modes was 2.41 and 0.35 mSv with O-arm®O2 (Low Dose 3D-small-abdomen) and Surgivisio® (3DSU-91 images), respectively. PCXMC results were consistent: 1.54 and 0.30 mSv. Organ doses were 5 to 12 times lower with Surgivisio®. K_i at patient skin were comparable on lateral 2D-imaging (0.5 mGy), but lower with O-arm®O2 on anteroposterior (0.3 versus 0.9 mGy). Both systems show poor low contrast resolution and similar high contrast spatial resolution (7 line-pairs/cm).

CONCLUSIONS

This study is the first to evaluate patient ED and organ doses with Surgivisio®. A significant difference in organs doses was observed between the CBCT systems. The study demonstrates that Surgivisio® used on spine delivers approximately five to six times less patient ED, compared to O-arm®O2, in low dose 3D-modes. Doses in 2D-mode preceding CBCT were higher with Surgivisio®, but negligible compared to CBCT doses under the experimental conditions tested.

Radiation Exposure in Posterior Lumbar Fusion: A Comparison of CT Image-Guided Navigation, Robotic Assistance, and Intraoperative Fluoroscopy

STUDY DESIGN

Retrospective clinical review.

OBJECTIVE

To assess the use of intraoperative computed tomography (CT) image-guided navigation (IGN) and robotic assistance in posterior lumbar surgery and their relationship with patient radiation exposure and perioperative outcomes.

METHODS

Patients ≥18 years old undergoing 1- to 2-level transforaminal lateral interbody fusion in 12-month period were included. Chart review was performed for pre- and intraoperative data on radiation dose and perioperative outcomes. All radiation doses are quantified in milliGrays (mGy). Univariate analysis and multivariate logistic regression analysis were utilized for categorical variables. One-way analysis of variance with post hoc Tukey test was used for continuous variables.

RESULTS

A total of 165 patients were assessed: 12 IGN, 62 robotic, 56 open, 35 fluoroscopically guided minimally invasive surgery (MIS). There was a lower proportion of women in open and MIS groups (P = .010). There were more younger patients in the MIS group (P < .001). MIS group had the lowest mean posterior levels fused (P = .015). Total-procedure radiation, total-procedure radiation/level fused, and intraoperative radiation was the lowest in the open group and highest in the MIS group compared with IGN and robotic groups (all P < .001). Higher proportion of robotic and lower proportion of MIS patients had preoperative CT (P < .001). Estimated blood loss (P = .002) and hospital length of stay (P = .039) were lowest in the MIS group. Highest operative time was observed for IGN patients (P < .001). No differences were observed in body mass index, Charlson Comorbidity Index, and postoperative complications (P = .313, .051, and .644, respectively).

CONCLUSION

IGN and robotic assistance in posterior lumbar fusion were associated with higher intraoperative and total-procedure radiation exposure than open cases without IGN/robotics, but significantly less than MIS without IGN/robotics, without differences in perioperative outcomes. Fluoro-MIS procedures reported highest radiation exposure to patient, and of equal concern is that the proportion of total radiation dose also applied to the surgeon and operating room staff in fluoro-MIS group is higher than in IGN/robotics and open groups.

Safety Profile, Surgical Technique, and Early Clinical Results for Simultaneous Lateral Lumbar Interbody Fusion and Anterior Lumbar Interbody Fusion in a Lateral Position

STUDY DESIGN

Description of surgical technique and retrospective review.

OBJECTIVE

To describe a novel surgical technique for multilevel lumbar fusion and describe early clinical results.

SUMMARY OF BACKGROUND DATA

Patients with multilevel lumbar spinal stenosis and adult degenerative scoliosis often require multilevel interbody placement to achieve indirect decompression and lordosis. We describe a case series of patients treated with simultaneous lateral lumbar interbody fusion (LLIF) and anterior lumbar interbody fusion (ALIF) at L5-S1.

METHODS

We retrospectively reviewed a consecutive series of patients treated for multilevel lumbar spinal stenosis with simultaneous ALIF and LLIF with at least 3-month follow-up. All patients received supplemental percutaneous bilateral pedicle screw placement as well. We measured on preoperative radiographs their lumbar lordosis, pelvic incidence, and L5-S1 lordosis. Intraoperative factors such as operative time, estimated blood loss, fluids provided, number of levels fused, and whether a trainee was present during the procedure were all recorded.

RESULTS

There were 15 patients included within our case series (69.5, 4 F). There were no reported intraoperative vascular or neurological complications in 15 cases. The operative time for the cases ranged from 2.7 to 8.4 hours (average=5.2±1.9 h). The average lordosis gained at L5-S1 was 8.6±3.0 degrees and the average lumbar lordosis gained was 14.7±6.4 degrees. The average PI-LL mismatch went from 22.4±13.3 degrees preoperative to 7.8±10.2 degrees postoperative. One patient had a postoperative complication of a sacral fracture requiring placement of a pelvic screw for a L2-pelvis fusion. There were 8 patients with 4+ levels of fusion. For this cohort of patients, the average lumbar lordosis gained was 16.0±7.5 degrees and the average PI-LL mismatch went from 24.7±16.3 degrees preoperative to 8.8±12.9 degrees postoperative. For the patients with 4+ levels of fusion, the average operative time was 5.9±1.8 hours.

CONCLUSIONS

We have described our early positive results with simultaneous LLIF/ALIF surgery for treatment of lumbar degenerative conditions.

Transfacet screws using spinal navigation in addition to anterior or oblique lumbar interbody fusion: technical note and preliminary results

Transfacet screws (TFS) are an alternative to the classic bilateral pedicular screws (BPS) in addition to anterior (ALIF) or oblique (OLIF) lumbar interbody fusion. Spinal navigation could help the surgeon in technically demanding procedures in order to avoid screw malposition. Although spinal navigation is commonly used in BPS, its contribution in TFS remains unclear. Our aim here was to assess the feasibility of TFS using spinal navigation in addition to anterior lumbar fusion. Five patients suffering from lumbar degenerative disc disease were included. During the same general anaesthesia, we performed successively an ALIF or OLIF and then a TFS according to Boucher technique using spinal navigation (O-arm). No peri-operative complication occurred, and all the screws were successfully positioned (n = 10). All clinical scores (ODI, VAS L and VAS R) improved at 6-month follow-up. Segmental lordosis increased from 6° [2.4°-12°] to 13.6° [8°-17°]. Fusion was achieved for the five patients. TFS using O-arm in addition to ALIF/OLIF is feasible. To confirm our early favourable outcomes on clinical and radiological data, this technique must be evaluated on larger samples of patients.

Narrative review of intraoperative image guidance for transforaminal lumbar interbody fusion

Recent advancements in imaging technology have changed the landscape of transforaminal lumbar interbody fusion (TLIF) with the objective of improving safety and efficacy for the patient and surgical team. Spine surgery, and specifically TLIFs, involve challenging anatomy and command precise surgical accuracy, creating an essential role for intraoperative imaging, navigation, and robotics. Traditionally, surgeons have relied upon fluoroscopy for pedicle screw and interbody placement. More recently, intraoperative 3-dimensional navigation (ION) has risen in popularity in TLIF surgery. This technology utilizes intra-operative advanced imaging, such as computed tomography (CT) and 3D-fluroscopy, to accurately track instruments and implants in relation to the patient's anatomy. ION has demonstrated improved accuracy of pedicle screw placement, decreased operating room times, and lower radiation exposure to the surgeon and staff. However, conventional fluoroscopy, 3D fluoroscopy, intraoperative CT, image-guided navigation, and robot-assisted surgery all have a role in TLIF surgery. Numerous studies have been published regarding the benefits and pitfalls of these intraoperative tools in spine surgery, but there is a relative lack of research regarding some of the newer technologies surrounding TLIF. As future studies are published, and technology continues to evolve, surgeons must stay abreast of novel techniques to maximize patient safety and outcomes. Over the coming decade, we can expect intraoperative navigation and robotics to play a more significant role in spine surgery.

Intraoperative image guidance for the surgical treatment of adult spinal deformity

Operative management of adult spinal deformity (ASD) has been increasing in recent years secondary to an aging society. The advance of intraoperative image guidance, such as the development of navigation and robotics systems has contributed to the growth and safety of ASD surgery. Currently, intraoperative image guidance is mainly used for pedicle screw placement and the evaluation of alignment correction in ASD surgery. Though it is expected that the use of navigation and robotics would result in increasing pedicle screw accuracy as reported in other spine surgeries, there are no well-powered studies specifically focusing on ASD surgery. Currently, deformity correction relies heavily on preoperative planning, however, a few studies have shown the possibility that intraoperative image modalities may accurately predict postoperative spinopelvic parameters. Future developments of intraoperative image guidance are needed to overcome the remaining challenges in ASD surgery such as radiation exposure to patient and surgeon. More novel imaging modalities may result in evolution in ASD surgery. Overall there is a paucity of literature focusing on intraoperative image guidance in ASD surgery, therefore, further studies are warranted to assess the efficacy of intraoperative image guidance in ASD surgery. This narrative review sought to provide the current role and future perspectives of intraoperative image guidance focusing on ASD surgery.

Intraoperative image guidance for lateral position surgery

Recent advances in minimally invasive spine surgery techniques have precipitated the popularity of lateral position spine surgery, such as lateral lumbar interbody fusion (LLIF) and oblique lumbar interbody fusion (OLIF). Lateral position surgery offers a unique, minimally invasive approach to the lumbar spine that allows for preservation of anterior and posterior spinal elements. Traditionally, surgeons have relied upon fluoroscopy for triangulation and implant placement. Over the last decade, intraoperative 3-dimensional navigation (ION) has risen to the forefront of innovation in LLIF and OLIF. This technology utilizes intra-operative advanced imaging, such as comminuted tomography (CT), to map the patient’s 3D anatomy and allows the surgeon to accurately visualize instruments and implants in spatial relationship to the patient’s anatomy in real time. ION has the potential to improve accuracy during instrumentation, decrease operating room times, lower radiation exposure to the surgeon and staff, and increase feasibility of single-position surgery during which the spine is instrumented both laterally and posteriorly while the patient remains in the lateral decubitus position. Despite the advantages of ION, the intra-operative radiation exposure risk to patients is controversial. Future directions include continued innovation in ultra low radiation imaging (ULRI) techniques and image enhancement technology and in uses of robot-assisted navigation in single-position spine surgery.

Intraoperative risks of radiation exposure for the surgeon and patient

Intraoperative radiological imaging serves an essential role in many spine surgery procedures. It is critical that patients, staff and physicians have an adequate understanding of the risks and benefits associated with radiation exposure for all involved. In this review, we briefly introduce the current trends associated with intraoperative radiological imaging. With the increased utilization of minimally invasive spine surgery (MIS) techniques, the benefits of intraoperative imaging have become even more important. Less surgical exposure, however, often equates to an increased requirement for intraoperative imaging. Understanding the conventions for radiation measurement, radiological fundamental concepts, along with deterministic or stochastic effects gives a framework for conceptualizing how radiation exposure relates to the risk of various sequela. Additionally, we describe the various options surgeons have for intraoperative imaging modalities including those based on conventional fluoroscopy, computer tomography, and magnetic resonance imaging. We also describe different ways to prevent unnecessary radiation exposure including dose reduction, better education, and use of personal protective equipment (PPE). Finally, we conclude with a reflection on the progress that has been made to limit intraoperative radiation exposure and the promise of future technology and policy.

Effective dose of radiation per screw in surgery of adolescent idiopathic scoliosis: matched pair analysis of 293 pedicle screws inserted using three different techniques

PURPOSE

Reports on heterogenous groups of patients have indicated that pedicle screw insertion guided by navigation (PIN) leads to, for the patient, higher doses of radiation compared with pedicle screw insertion guided by fluoroscopy (PIF). This would be a major concern, especially in paediatric deformity correction.

METHODS

After a power analysis (aiming at > 0.8) 293 pedicle screws which were inserted in patients with adolescent idiopathic scoliosis were analyzed by comparing effective dose and fluoroscopy time per screw for three different techniques. Groups 2 and 3 were matched to Group 1 by Lenke type of scoliosis. Group 1 were prospectively enrolled consecutive patients that have been operated on by PIN with image acquisition by preoperative CT scan (CTS). Group 2 were consecutive retrospectively matched patients who have been operated on by PIN with image acquisition by an intraoperative 3D scan (3DS). Group 3 were consecutive retrospectively matched patients who have been operated on by PIF.

RESULTS

Mean dose of radiation per screw was 1.0 mSv (sd 0.8) per screw in CTS patients, 0.025 mSv (sd 0.001) per screw in 3DS patients and 0.781 mSv (sd 0.12) per screw in PIF patients. The difference was significant (p < 0.0001).

CONCLUSION

When we compared different techniques of navigation, navigation by image acquisition with CTS showed a significantly higher (by 97.5%) dose of radiation per screw for the patient than navigation by image acquisition by a 3DS. Navigation by 3DS showed significantly lower effective dose per screw for the adolescent patients than the fluoroscopic technique.

LEVEL OF EVIDENCE

II.

Computer-Assisted Orthopedic and Trauma Surgery

BACKGROUND

There are many ways in which computer-assisted orthopedic and trauma surgery (CAOS) procedures can help surgeons to plan and execute an intervention.

METHODS

This study is based on data derived from a selective search of the literature in the PubMed database, supported by a Google Scholar search.

RESULTS

For most applications the evidence is weak. In no sector did the use of computer-assisted surgery yield any relevant clinical or functional improvement. In trauma surgery, 3D-navigated sacroiliac screw fixation has become clinically established for the treatment of pelvic fractures. One randomized controlled trial showed a reduction in the rate of screw misplacement: 0% with 3D navigation versus 20.4% with the conventional procedure und 16.6% with 2D navigation. Moreover, navigation-assisted pedicle screw stabilization lowers the misplacement rate. In joint replacements, the long-term results showed no difference in respect of clinical/functional scores, the time for which the implant remained in place, or aseptic loosening.

CONCLUSION

Computer-assisted procedures can improve the precision of certain surgical interventions. Particularly in joint replacement and spinal surgery, the research is moving away from navigation in the direction of robotic procedures. Future studies should place greater emphasis on clinical and functional results.

Use of an inertial measurement unit sensor in pedicle screw placement improves trajectory accuracy

Ascertaining the accuracy of the pedicle screw (PS) trajectories is important as PS malpositioning can cause critical complications. We aimed to determine the angle range over which estimation is unreliable; build a low-cost PS placement support system that uses an inertial measurement unit (IMU) to enable the monitoring of surgical tools and PS trajectories, and determine the situations where IMU support would be most beneficial. In PS insertion experiments, we used cadaver samples that included lumbar porcine spines. Computed tomography images obtained before and after PS insertion were viewed. Offsets between the planned and implanted PS trajectories in the freehand and IMU-assisted groups were analyzed. The PS cortical bone breaches were classified according to the Gertzbein and Robbins criteria (GRC). Added head-down tilted sample experiments were repeated wherein we expected a decreased rostro-caudal rotational accuracy of the PS according to the angle estimation ability results. Evaluation of the PS trajectory accuracy revealed no significant advantage of IMU-assisted rostro-caudal rotational accuracy versus freehand accuracy. According to the GRC, IMU assistance significantly increased the rate of clinically acceptable PS positions (RoCA) than the freehand technique. In the head-down tilted sample experiments, IMU assist provided increased accuracies with both rostro-caudal and medial rotational techniques when compared with the freehand technique. In the freehand group, RoCA was significantly decreased in samples with rostral tilting relative to that in the samples without. However, In the IMU-assisted group, no significant difference in RoCA between the samples with and without head-down tilting was observed. Even when the planned PS medial and/or rostro-caudal rotational angle was relatively large and difficult to reproduce manually, IMU-support helped maintain the PS trajectory accuracy and positioning safety. IMU assist in PS placement was more beneficial, especially for larger rostro-caudal and/or medial rotational pedicle angles.

The effectiveness of a free-standing lead-shield in reducing spine surgeon radiation exposure during intraoperative 3-dimensional imaging

BACKGROUND

CONTEXT Intraoperative three-dimensional (3D) computed tomography (CT) imaging has become increasingly popular in spine surgery. Previous spine surgeon radiation exposure research has focused largely on procedures using fluoroscopy, however, few studies have been performed on the subject since the introduction of the 3D imaging systems. As a result, concerns have re-emerged over surgeon radiation exposure and the effectiveness of operating room (OR) protocols for decreasing workplace radiation. Current radiation safety guidelines require surgeons wear full body protective lead while any type of radiation is being administered during surgery. As a result, local institutions do not allow for the use of free-standing lead shields for sole radiation protection in the operating room. However, there is no data available to demonstrate whether the additional personal lead is required, or if in fact the lead shield alone is sufficient.

PURPOSE

This study investigated the effectiveness of a free-standing lead shield in reducing spine surgeon radiation exposure in the operating room during intraoperative imaging.

STUDY DESIGN/SETTING

A prospective clinical research study at a large, tertiary care center.

PATIENT SAMPLE

Twenty-seven patients undergoing instrumented spinal procedures between June and August 2019.

OUTCOME MEASURES

Fluoroscopy time, total fluoroscopy dose delivered, 3D dose delivered, total 3D spins, number of HD spins, number of standard spins, number of fluoroscopic images, number of spine levels operated on, patient size setting, shield distance from patient, radiation dose in front of shield, radiation dose behind shield.

METHODS

Twenty-seven instrumented spinal procedures using the O-Arm Imaging System (Medtronic, Minneapolis, MN) were observed to determine radiation exposure to a spine surgeon standing behind a lead shield in the OR. Two thermoluminescent dosimeters were used to measure scatter radiation in front of and behind lead shields. Both fluoroscopy and intraoperative CT based radiation exposure was recorded. The dosimeter readings were compared to determine the degree of radiation attenuation by the lead shield. Regression analysis of the exposure values from behind the shield, shield distance from the patient, and radiation dose delivered by the imaging system was utilized to estimate the number of cases required to surpass annual exposure limits. Case numbers were calculated for the highest "worst case" and "average case" exposure values. The safe annual occupation exposure limit determined by the National Council on Radiation Protection is five roentgen equivalent man (rem) or 50,000 microsieverts (μSv).

RESULTS

Average surgeon radiation exposure per case was 0.694 μSv (SD: 0.501, Range: 0.105-2.167) behind the lead shield compared to 14.577 μSv (SD: 9.864, Range: 2.185-44.492) in front of the lead shield. The average radiation dose reduction by the lead shield was 13.962 μSv (SD: 9.49, Range: 2.08-42.72) per case, which is equivalent to an average of 95.65% (SD: 1.71) radiation attenuation by lead shielding. If surgeons stand behind lead shields in the OR, the annual number of 3D image-guided spinal procedures required to surpass exposure limits is 15,479 and 67,060 based on "worst case" and "average case" analyses, respectively.

CONCLUSIONS

Our study demonstrates standing behind intraoperative lead shields is very effective at decreasing radiation exposure to surgeons. Additionally, surgeon radiation doses behind lead shielding fall far below annual exposure limits. Surgeons should not need additional protective equipment when a lead shield is used.

Clinical application of intraoperative O-arm navigation in reverse shoulder arthroplasty

BACKGROUND

Inaccurate fixation and positioning of the glenoid component using conventional techniques are problematic in reversed shoulder arthroplasty (RSA). Our objective was to investigate the accuracy of O-arm navigation of the glenoid component in RSA.

METHODS

This retrospective case-control study comprised 2 groups of 25 patients who underwent reversed shoulder arthroplasty with or without intraoperative O-arm navigation. The intraoperative goal was to place the component neutrally in the glenoid in the axial plane and 10° inferiorly tilted in the scapular plane. Glenoid version angle and inclination were measured by computed tomography obtained preoperatively and a year postoperatively. Operative time, intraoperative bleeding, and the presence of postoperative complications were recorded.

RESULTS

Compared with the ideal, the range of error for version was 7.3° (SD 3.6°) in the control group and 5.6° (SD 3.6°) in the navigated group (P = 0.278), and the range of error for inclination was 18.3° (SD 11.7°) in the control group and 4.9° (SD 3.8°) in the navigated group (P = 0.0004). The mean operative time was 164.6 (SD 21.2) min in the control group and 192.0 (SD 16.2) min in the navigated group (P = 0.001). The mean intraoperative bleeding was 201.0 (SD 37.0) mL in the control group and 185.3 (SD 35.6) mL in the navigated group (P = 0.300). There were no complications reported related to the intraoperative O-arm navigation.

CONCLUSION

O-arm navigation may be a useful tool for the placement with inferior tilt of the glenoid procedure in reversed shoulder arthroplasty.

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

BACKGROUND

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.

METHODS

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.

RESULTS

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.

CLINICAL RELEVANCE

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.

Prospective Evaluation of the Time Required for Insertion of 380 Lumbar and Sacral Pedicle Screws Using Navigation with an Intraoperative 3-Dimensional Imaging System

Background

The aim of this study was to evaluate the time required for various parts of the procedure to insert lumbar and sacral pedicle screws using navigation with an intraoperative, 3-dimensional imaging system. Comparison of these timings was carried out for different surgical indications.

Methods

This was a single-surgeon prospective cohort study of 69 consecutive patients (between August 2013 and June 2018) who underwent insertion of 380 pedicle screws into the lumbar and sacral vertebrae. Surgical indications, average time required for surgical exposure and attachment of the reference frame, average time required until completion of the first pedicle screw insertion, and average time required for insertion of a single pedicle screw were evaluated.

Results

The average time required from skin incision to reference frame attachment was 28.3 ± 20.4 (mean ± SD) minutes, and the average time required from reference frame attachment to completion of first pedicle screw insertion was 22.3 ± 9.6 minutes. The average time required for insertion of a single pedicle screw was 7.8 ± 2.7 minutes. When surgical indications were compared, the average time required for insertion of a single pedicle screw was 7.7 ± 2.6 minutes in surgery for spondylosis-related stenosis, 8.1 ± 2.8 minutes for degenerative scoliosis, and 8.2 ± 3.6 minutes for metastatic tumor (P = .89). There were no significant changes in these timings over consecutive 6-month periods.

Conclusions

There is no significant learning curve and no significant difference in navigation setup and pedicle screw insertion timings with intraoperative 3-dimensional navigation systems for surgeries of different pathologies and levels of surgery.

Level of Evidence

2.

Is the Additional Effort for an Intraoperative CT Scan Justified for Distal Radius Fracture Fixations? A Comparative Clinical Feasibility Study

INTRODUCTION

It is currently unclear whether the additional effort to perform an intraoperative computed tomography (CT) scan is justified for articular distal radius fractures (DRFs). The purpose of this study was to assess radiological, functional, and clinical outcomes after surgical treatment of distal radius fractures when using conventional fluoroscopy vs. intraoperative CT scans.

METHODS

Inclusion criteria: Surgical treatment of DRF between 1 January 2011 and 31 December 2011, age 18 and above. Group distribution: intraoperative conventional fluoroscopy (Group Conv) or intraoperative CT scans (Group CT).

EXCLUSION CRITERIA

Use of different image intensifier devices or incomplete data. DRF classification according to the Arbeitsgemeinschaft für Osteosynthesefragen (AO) classification. Outcome variables included requirement of revision surgeries, duration of surgery, absorbed radiation dose, and requirement of additional CT scans during hospitalization.

RESULTS

A total of 187 patients were included (Group Conv n = 96 (51.3%), Group CT n = 91 (48.7%)). AO Classification: Type A fractures n = 40 (50%) in Group Conv vs. n = 16 (17.6%) in Group CT, p < 0.001; Type B: 10 (10.4%) vs. 11 (12.1%), not significant (n.s.); Type C: 38 (39.6%) vs. 64 (70.3%), p < 0.001. In Group Conv, four (4.2%) patients required revision surgeries within 6 months, but in Group CT no revision surgery was required. The CT scan led to an intraoperative screw exchange/reposition in 23 (25.3%) cases. The duration of the initial surgery (81.7 ± 46.4 min vs. 90.1 ± 43.6 min, n.s.) was comparable. The radiation dose was significantly higher in Group CT (6.9 ± 1.3 vs. 2.8 ± 7.8 mGy, p < 0.001). In Group Conv, 11 (11.5%) patients required additional CT scans during hospitalization.

CONCLUSION

The usage of intraoperative CT was associated with improved reduction and more adequate positioning of screws postoperatively with comparable durations of surgery. Despite increased efforts by utilizing the intraoperative CT scan, the decrease in reoperations may justify its use.

The state-of-the-art in ultrasound-guided spine interventions

During the last two decades, intra-operative ultrasound (iUS) imaging has been employed for various surgical procedures of the spine, including spinal fusion and needle injections. Accurate and efficient registration of pre-operative computed tomography or magnetic resonance images with iUS images are key elements in the success of iUS-based spine navigation. While widely investigated in research, iUS-based spine navigation has not yet been established in the clinic. This is due to several factors including the lack of a standard methodology for the assessment of accuracy, robustness, reliability, and usability of the registration method. To address these issues, we present a systematic review of the state-of-the-art techniques for iUS-guided registration in spinal image-guided surgery (IGS). The review follows a new taxonomy based on the four steps involved in the surgical workflow that include pre-processing, registration initialization, estimation of the required patient to image transformation, and a visualization process. We provide a detailed analysis of the measurements in terms of accuracy, robustness, reliability, and usability that need to be met during the evaluation of a spinal IGS framework. Although this review is focused on spinal navigation, we expect similar evaluation criteria to be relevant for other IGS applications.

O-arm navigation versus C-arm guidance for pedicle screw placement in spine surgery: a systematic review and meta-analysis

BACKGROUND

O-arm and C-arm are commonly used in spine surgery to guide pedicle screw placement. However, concerning the accuracy and efficiency of them, no systematical review and meta-analyses are available to help surgeons make comparisons.

PURPOSES

This study aims to investigate the accuracy and efficiency of O-arm-navigated versus C-arm-guided pedicle screw placement in thoracic and lumbar spine surgery. It would help surgeons choose the optimal technique for pedicle screw placement.

PATIENTS AND METHODS

A systematic review and meta-analyses were performed after searching the PubMed, Embase, and Cochrane databases to identify all studies that assessed the accuracy and efficiency of navigation coupled with O-arm and conventional C-arm fluoroscopy.

RESULTS

Eight studies were finally recruited in this systematic review, all of which reported pedicle screw placement outcomes related to accuracy or efficiency in both C-arm and O-arm groups. Five studies showed higher screw insertion accuracy in the O-arm group, while one study showed no significant difference. And the pooled results also indicated that the incidence of screw misplacement in the C-arm groups is higher. Moreover, the pooled results from five studies indicated no significant difference in insertion time between C-arm and O-arm.

CONCLUSIONS

Navigation coupled with O-arm imaging displayed a lower efficiency outcome in pedicle screw placement compared to conventional C-arm fluoroscopy. However, in terms of accuracy, O-arm navigation had significant advantages in accuracy over conventional C-arm fluoroscopy.

Image-Guided Navigation and Robotics in Spine Surgery

Image guidance (IG) and robotics systems are becoming more widespread in their utilization and can be invaluable intraoperative adjuncts during spine surgery. Both are highly reliant upon stereotaxy and either pre- or intraoperative radiographic imaging. While user-operated IG systems have been commercially available longer and subsequently are more widely utilized across centers, robotics systems provide unique theoretical advantages over freehand and IG techniques for placing instrumentation within the spine. While there is a growing plethora of data showing that IG and robotic systems decrease the incidence of malpositioned screws, less is known about their impact on clinical outcomes. Both robotics and IG may be of particular value in cases of substantial deformity or complex anatomy. Indications for the use of these systems continue to expand with an increasing body of literature justifying their use in not only guiding thoracolumbar pedicle screw placement, but also in cases of cervical and pelvic instrumentation as well as spinal tumor resection. Both techniques also offer the potential benefit of reducing occupational exposures to ionizing radiation for the operating room staff, the surgeon, and the patient. As the use of IG and robotics in spine surgery continues to expand, these systems' value in improving surgical accuracy and clinical outcomes must be weighed against concerns over cost and workflow. As newer systems incorporating both real-time IG and robotics become more utilized, further research is necessary to better elucidate situations where these systems may be particularly beneficial in spine surgery.

Intraoperative Use of O-arm in Pediatric Cervical Spine Surgery

INTRODUCTION

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.

METHODS

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.

RESULTS

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.

CONCLUSIONS

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 OF EVIDENCE

Level IV.

Accuracy of augmented reality surgical navigation for minimally invasive pedicle screw insertion in the thoracic and lumbar spine with a new tracking device

BACKGROUND CONTEXT

Minimally invasive approaches are increasingly used in spine surgery. The purpose of navigation systems is to guide the surgeon and to reduce intraoperative x-ray exposure.

PURPOSE

This study aimed to determine the feasibility and clinical accuracy of a navigation technology based on augmented reality surgical navigation (ARSN) for minimally invasive thoracic and lumbar pedicle screw instrumentation compared with standard fluoroscopy-guided minimally invasive technique.

STUDY DESIGN/SETTING

Cadaveric laboratory study.

METHODS

ARSN was installed in a hybrid operating room, consisting of a flat panel detector c-arm with two dimensional/three dimensional imaging capabilities and four integrated cameras in its frame. The surface-referenced navigation device does not require a bony reference but uses video cameras and optical markers applied to the patient's skin for tracking. In four cadavers, a total of 136 pedicle screws were inserted in thoracic and lumbar vertebrae. The accuracy was assessed by three independent raters in postoperative conventional computed tomography.

RESULTS

The overall accuracy of ARSN was 94% compared with an accuracy of 88% for fluoroscopy. The difference was not statistically significant. In the thoracic region, accuracy with ARSN was 92% compared with 83% with fluoroscopy. With fluoroscopy, unsafe screws were observed in three normal cadavers and one with scoliosis. Using ARSN, unsafe screws were only observed in the scoliotic spine. No significant difference in the median of time for K-wire placement was recorded. As no intraoperative fluoroscopy was necessary in ARSN, the performing surgeon was not exposed to radiation.

CONCLUSIONS

In this limited cadaveric study minimally invasive screw placement using ARSN was demonstrated to be feasible and as accurate as fluoroscopy. It did not require any additional navigation time or use of any intraoperative x-ray imaging, thereby potentially permitting surgery in a protective lead garment-free environment. A well-powered clinical study is needed to demonstrate a significant difference in the accuracy between the two methods.

CLINICAL SIGNIFICANCE

ARSN offers real-time imaging of planned insertion paths, instrument tracking, and overlay of three dimensional bony anatomy and surface topography. The referencing procedure, by optical recognition of several skin markers is easy and does not require a solid bony reference as necessary for conventional navigation which saves time. Additionally, ARSN may foster the reduction of intraoperative x-ray exposure to spinal surgeons.

Comparison of low-dose CT with CT/CT fluoroscopy guidance in percutaneous sacral and supra-acetabular cementoplasty

PURPOSE

Percutaneous cementoplasty is a minimally invasive treatment modality for painful osteoporotic and pathologic sacral and supra-acetabular iliac fractures. This study compares the use of low-dose CT guidance with CT/CT fluoroscopy in sacral and supra-acetabular cementoplasty.

METHODS

A retrospective review of patients who had undergone sacral or supra-acetabular cementoplasty was performed with patients grouped by use of CT/CT fluoroscopy or low-dose CT guidance during the procedure. Parameters evaluated included type of fracture, laterality of lesions, pain scores, pain medication use, imaging parameters, procedure time, dose-length product, effective dose, cement volume, and complications.

RESULTS

There were 17 patients identified who underwent cementoplasty utilizing dual CT/CT fluoroscopy, while 13 patients had their procedures performed with low-dose CT. There was a statistically significant decrease in radiation dose in the low-dose CT group (1481 mGy•cm) compared with the CT/CT fluoroscopy group (2809 mGy•cm) (P = 0.013). There was a significant decrease in procedure time with low-dose CT for bilateral lesions (P = 0.016). There was no significant difference between groups in complication rate (P = 0.999). Clinically nonsignificant cement extravasation occurred in two patients (10%) in the CT/CT fluoroscopy group and in one patient (8%) in the low-dose CT group (P = 0.999). There was a significant decrease in pain scores compared with baseline on the visual analogue scale in both groups at 1 week (low-dose CT P = 0.002, CT/CT fluoroscopy P = 0.008) and 1 month postprocedure (low-dose CT P = 0.014, CT/CT fluoroscopy P = 0.004), but no difference between groups at 1 day (P = 0.196), 1 week (P = 0.368), or 1 month (P = 0.514).

CONCLUSION

Sacral and supra-acetabular cementoplasties can be performed safely and precisely using low-dose multiple-acquisition CT guidance while providing significant radiation dose reduction with no difference in extravasation rates, postprocedural pain reduction, and complications compared with CT/CT fluoroscopy.

Percutaneous short-segment pedicle instrumentation assisted with O-arm navigation in the treatment of thoracolumbar burst fractures

Object

To compare the clinical and radiological outcomes of O-arm navigation assisted percutaneous pedicle fixation and open freehand pedicle fixation in treatment of AO type A3 thoracolumbar burst fractures (TBFs) without neurological deficit.

Methods

This retrospective study involved 72 patients with type A3 TBFs who underwent O-arm navigation assisted percutaneous pedicle fixation (MIS group) or open freehand posterior pedicle fixation (OPPF group) from September 2015 to December 2017. Demographic data and clinical characteristics were comparable between these two groups before surgery. Operating time, intraoperative blood loss, and the time of hospitalisation stay were analysed. Visual analog scale (VAS) scoring and Oswestry disability index (ODI) was assessed for each patient pre- and postoperatively. Radiographic follow-up was assessed by the Local kyphosis angle (LKA), Vertebral wedge angle (VWA), and Anterior body height (ABH). The accuracy of screw placement was examined by computed tomography.

Results

The two groups were matched in terms of demographic and clinical features. Intraoperative blood loss was significantly less in the MIS group compared to the OPPF group (p < 0.05). The average time for hospitalisation stay in the MIS group was significantly shorter than OPPF group (p < 0.05). However, the operative time revealed no significant difference between two groups (p > 0.05). Meanwhile, the VAS score and ODI score in the MIS group were significantly lower than that in the OPPF group after surgery (p < 0.05). Radiographic assessments revealed no obvious difference between the 2 groups immediately after surgery or at the final follow-up (p > 0.05); The accuracy rate of pedicle screw position in the MIS group was higher than OPPF group (97.8% vs 78.5%, respectively; p < 0.001). No deep wound infection, additional surgery, implant failure, or neurological complications were recorded in either group.

Conclusions

Percutaneous short-segment pedicle instrumentation assisted with O-arm navigation represents an effective and safe alternative for type A3 TBFs. It has several advantages compared with open approach, including less blood loss, shorter hospitalisation, less postoperative pain, higher accuracy of pedicle screw placement, and faster recovery period in treating TBFs. However, it requires a longer learning curve and long-term results have to be studied in other well-designed studies.

The translational potential of this article

Percutaneous short-segment pedicle instrumentation assisted with O-arm navigation represents an effective and safe alternative for type A3 TBFs. The utilization of O-arm navigation and percutaneous pedicle screw fixation guaranteed the high accuracy of screw placement, protected staff from radiation exposure and offered benefits of minimal invasive technique.

Evaluation of surgeon and patient radiation exposure by imaging technology in patients undergoing thoracolumbar fusion: systematic review of the literature

BACKGROUND CONTEXT

Minimally invasive spine techniques are becoming increasingly popular owing to their ability to reduce operative morbidity and recovery times. The downside to these new procedures is their need for intraoperative radiation guidance.

PURPOSE

To establish which technologies provide the lowest radiation exposure to both patient and surgeon.

STUDY DESIGN/SETTING

Systematic review OUTCOME MEASURES: Average intraoperative radiation exposure (in mSv per screw placed) to surgeon and patient. Average fluoroscopy time per screw placed.

METHODS

We reviewed the available English medical literature to identify all articles reporting patient and/or surgeon radiation exposure in patients undergoing image-guided thoracolumbar instrumentation. Quantitative meta-analysis was performed for studies providing radiation exposure or fluoroscopy use per screw placed to determine which navigation modality was associated with the lowest intraoperative radiation exposure. Values on meta-analysis were reported as mean ± standard deviation.

RESULTS

We identified 4956 unique articles, of which 85 met inclusion/exclusion criteria. Forty-one articles were included in the meta-analysis. Patient radiation exposure per screw placed for each modality was: conventional fluoroscopy without navigation (0.26±0.38 mSv), conventional fluoroscopy with pre-operative CT-based navigation (0.027±0.010 mSv), intraoperative CT-based navigation (1.20±0.91 mSv), and robot-assisted instrumentation (0.04±0.30 mSv). Values for fluoroscopy used per screw were: conventional fluoroscopy without navigation (11.1±9.0 seconds), conventional fluoroscopy with navigation (7.20±3.93 s), 3D fluoroscopy (16.2±9.6 s), intraoperative CT-based navigation (19.96±17.09 s), and robot-assistance (20.07±17.22 s). Surgeon dose per screw: conventional fluoroscopy without navigation (6.0±7.9 × 10^-3 mSv), conventional fluoroscopy with navigation (1.8±2.5 × 10^-3 mSv), 3D Fluoroscopy (0.3±1.9 × 10^-3 mSv), intraoperative CT-based navigation (0±0 mSv), and robot-assisted instrumentation (2.0±4.0 × 10^-3 mSv).

CONCLUSION

All image guidance modalities are associated with surgeon radiation exposures well below current safety limits. Intraoperative CT-based (iCT) navigation produces the lowest radiation exposure to surgeon albeit at the cost of increased radiation exposure to the patient relative to conventional fluoroscopy-based methods.

Accuracy of Current Techniques for Placement of Pedicle Screws in the Spine: A Comprehensive Systematic Review and Meta-Analysis of 51,161 Screws

BACKGROUND

Pedicle screws (PSs) are routinely used for stabilization to enhance fusion in a variety of spinal diseases. Although the accuracy of different PS placement methods has been previously reported, most of these studies have been limited to 1 or 2 techniques. The purpose was to determine the current accuracy of PS placement among 4 modalities of PS insertion (freehand [FH], fluoroscopy-assisted [FA], computed tomography navigation-guided [CTNav], and robot-assisted [RA]) and analyze variables associated with screw misplacement.

METHODS

A systematic review was performed of peer-reviewed articles reporting PS accuracy of 1 technique from January 1990 to June 2018. Accuracy of PS placement, PS insertion technique, and pedicle breach (PB) data were collected. A meta-analysis was performed to estimate the overall pooled (OP) rates of PS accuracy as a primary outcome, stratified by screw insertion techniques. Potential determinants were analyzed via meta-regression analyses.

RESULTS

Seventy-eight studies with 7858 patients, 51,161 PSs, and 3614 cortical PBs were included. CTNav showed the highest PS placement accuracy compared with other techniques: OP accuracy rates were 95.5%, 93.1%, 91.5%, and 90.5%, via CTNav, FH, FA, and RA techniques, respectively. RA and CTNav were associated with the highest PS accuracy in the thoracic spine, compared with FH.

CONCLUSIONS

The OP data show that CTNav has the highest PS accuracy rates. Thoracic PSs were associated with lower accuracy rates; however, RA showed fewer breaches in the thoracic spine compared with FH and FA. Given the heterogeneity among studies, further standardized and comparative investigations are required to confirm our findings.

Percutaneous fixation of thoracolumbar vertebral fractures

Surgical treatment of patients with thoracolumbar vertebral fracture without neurological deficit is still controversial.

Management of vertebral fracture with percutaneous fixation was first reported in 2004.

Advantages of percutaneous fixation are: less tissue dissection; decreased post-operative pain; decreased bleeding and operative time (depending on the steep learning curve); better screw positioning with fluoroscopy compared with an open freehand technique; and a decreased infection rate.

The limitations of percutaneous fixation of vertebral fractures include increased radiation exposure to the patient and the surgeon, together with the steep learning curve for this technique.

Adding a screw at the level of the fractured vertebra has the advantages of incorporating fewer motion segments with less operative time and bleeding. This also increases the axial, sagittal and torsional stiffness of the construct.

Percutaneous fixation alone without grafting is sufficient for treating type A and B1 (AO classification) thoracolumbar fractures with satisfactory results concerning kyphosis reduction when compared with open instrumentation and fusion and with open fixation.

Type C and B2 fractures (ligamentous injuries) should undergo fusion since the ligamentous healing is mechanically weak, increasing the risk of instability.

This review offers a detailed description of percutaneous screw insertion and discusses the advantages and disadvantages.

Cite this article: EFORT Open Rev 2018;3:604-613. DOI: 10.1302/2058-5241.3.170026.

ACCURACY OF PEDICLE SCREW INSERTION: A COMPARISON BETWEEN FLUOROSCOPIC GUIDANCE AND NAVIGATION TECHNIQUES

Objectives:

To compare the accuracy of insertion of pedicle screws into the thoracic spine using fluoroscopic guidance or computer-assisted navigation techniques.

Methods:

Eight cadaveric thoracic spines were divided into two groups: the fluoroscopy group, in which pedicle screws were inserted with the guidance of a C-arm device, and the navigation group, in which insertion of the screws was monitored using computer-assisted navigation equipment. All procedures were performed by the same spinal surgeon. The rate of pedicle breach was compared between the two groups.

Results:

There was one intra-canal perforation in each group. Both perforations were medial in direction, and the breaches were 2 to 4 mm deep. There were no statistically significant differences in breach rate between the two groups.

Conclusions:

The accuracy of insertion of pedicle screws in the thoracic spine using computer-assisted navigation is equivalent to that achieved using fluoroscopic guidance. Computer-assisted navigation improves the safety of the surgical team during the procedure due to the absence of exposure to radiation. Therefore, there is a need for future randomized controlled trials to be conducted in the clinical setting to evaluate other outcomes, including duration of surgery and blood loss during the procedure. Level of evidence IV.

Robot-assisted percutaneous placement of K-wires during minimally invasive interventions of the spine

Purpose: To assess the accuracy and time requirements of image-guided percutaneous K-wire insertion in the spine using an advanced robot assistance device for needle guidance and to demonstrate a radiation-free workflow for the physician. Material and methods: A planning CT-scan was acquired of a cadaver specimen and analyzed using a 3D-interventional software integrated in the robotic device. The optimal needle path was simulated and the needle holder of the robot was used for guidance during K-wire insertion. Twenty-four K-wires were inserted percutaneously in a transpedicular approach in the following vertebrae: thoracic (T) 2, 7-12 and lumbar (L) 1-5. A post-procedural CT scan was performed to analyze the accuracy of the K-wire insertion. Results: All procedures were carried out without any perforation of the pedicle wall. The mean duration of planning the intervention path was 2:54 ± 2:22 min, mean positioning time was 2:04 ± 0:42 min and the mean time for K-wire insertion was 2:13 ± 0:54 min. In total, the average intervention time was 7:10 ± 3:06 min per pedicle. Compared to the planning, the K-wire position showed a mean deviation of 0.5 mm in the vertical-axis and 1.2 mm in the horizontal-axis. The average intervention path length was 8.1 cm. Conclusion: Our findings show a high accuracy in robot-assisted K-wire insertion during spinal interventions without any exposure of the operator to radiation.

Patient Dose Comparison for Intraoperative Imaging Devices Used in Orthopaedic Lumbar Spinal Surgery

Background:

The aim of this study was to determine the amount of radiation exposure from intraoperative imaging during two-level and four-level lumbar fusions.

Methods:

Five imaging systems were studied: multidetector CT (MDCT) scanner (CT A); two mobile CT units (CT B and CT C); a C-arm (D); and fluoroscopy (E). Metal oxide semiconductor field effect transistor dosimeters measured doses at 25 organ locations using an anthropomorphic phantom. A fat-equivalent phantom was used to simulate an obese body mass index (BMI).

Results:

The effective dose (ED) for C-arm D was estimated using commercial software. The ED for others was computed from the measured mean organ doses. EDs for a normal BMI patient, receiving a four-level fusion, are as follows: CT A (12.00 ± 0.30 mSv), CT B (5.90 ± 0.25 mSv), CT C (2.35 ± 0.44 mSv), C-arm D (0.44 mSv), and fluoroscopy E (0.30 ± 0.3 mSv). The rankings are consistent across all three BMI values except CT C and fluoroscopy E, which peaked in the overweight size because of system limitations. The other machines' ED trended with patient BMI.

Conclusion:

The dose reduction protocols were confirmed according to the manufacturer's specifications. The results of this study emphasize the need for the appropriate selection of the imaging system, especially because the type of device could have a substantial effect on patient radiation risk.