Pedicle screw placement in the thoracic spine: a comparison study of computer-assisted navigation and conventional techniques

Surgical Management of Primary Thoracic Epidural Melanoma

In this study, we reported one of the first cases where a rare robotic-assisted platform with neuronavigation technology and carbon-fiber-polyetheretherketone (CF/PEEK) screws is employed to surgically treat multilevel thoracic primary spinal epidural melanoma. A 67-year-old male presented with left upper thoracic pain. His magnetic resonance imaging (MRI) of the thoracic spine revealed a dumbbell-shaped left epidural mass at the T2-3 level. Partial resection was performed due to tumor growth into the vertebral bodies and patient discretion for minimal surgery. The patient's neurological conditions improved postoperatively, with reduced reported symptoms of pain and numbness. Postoperative imaging showed evidence of appropriate spinal stabilization. Patient underwent stereotactic body radiation therapy (SBRT), and no adverse events were reported. This case reflects one of the first examples of treating thoracic epidural melanoma with the use of robotic-assisted navigation. Further prospective studies are needed to determine the efficacy of robot-assisted navigation for patients with primary spinal malignant melanoma which may open the possibility of surgery to once presumed non-operative patients.

Robotics and navigation in spine surgery: A narrative review

Introduction

In recent decades, there has been a rising trend of spinal surgical interventional techniques, especially Minimally Invasive Spine Surgery (MIS), to improve the quality of life in an effective and safe manner. However, MIS techniques tend to be difficult to adapt and are associated with an increased risk of radiation exposure. This led to the development of 'computer-assisted surgery' in 1983, which integrated CT images into spinal procedures evolving into the present day robotic-assisted spine surgery. The authors aim to review the development of spine surgeries and provide an overview of the benefits offered. It includes all the comparative studies available to date.

Methods

The manuscript has been prepared as per "SANRA-a scale for the quality assessment of narrative review articles". The authors searched Pubmed, Embase, and Scopus using the terms "(((((Robotics) OR (Navigation)) OR (computer assisted)) OR (3D navigation)) OR (Freehand)) OR (O-Arm)) AND (spine surgery)" and 68 articles were included for analysis excluding review articles, meta-analyses, or systematic literature.

Results

The authors noted that 49 out of 68 studies showed increased precision of pedicle screw insertion, 10 out of 19 studies show decreased radiation exposure, 13 studies noted decreased operative time, 4 out of 8 studies showed reduced hospital stay and significant reduction in rates of infections, neurological deficits, the need for revision surgeries, and rates of radiological ASD, with computer-assisted techniques.

Conclusion

Computer-assisted surgeries have better accuracy of pedicle screw insertion, decreased blood loss and operative time, reduced radiation exposure, improved functional outcomes, and lesser complications.

Robotic assistance in lumbar fusion surgery: trends and patterns from 2016-2019

PURPOSE

Robotic-assisted spine surgery is an emerging field that is growing in utilization. Intraoperative robotic surgical units cost upwards of $600,000 for medical facilities to purchase. Despite significant cost barriers, these devices are highly marketable for hospitals and physicians.

METHODS

The Nationwide Inpatient Sample database from 2016 to 2019 was reviewed. Inclusion criteria were patients over 18 years of age who underwent elective lumbar spinal fusion. Trends of robotic-assisted lumbar fusion were examined over time, as well as stratified based on patient and surgical characteristics.

RESULTS

A total of 176,377 patients met the inclusion criteria. The overall rate of robotic-assisted lumbar fusion was 1.2% (2,131/174,246). Patients with private insurance were more likely to receive robotic-assisted lumbar fusion (40.3% vs. 37.5%; p < 0.05). Stratifying by race, whites were more likely to receive robotic-assisted lumbar fusion (84.1% vs. 79.5%; p < 0.05). Patients who underwent robotic-assisted lumbar fusion were significantly more likely to have a diagnosis of spondylolisthesis compared to those that underwent non-robotic-assisted lumbar fusion (25.9% vs. 22.0%; p < 0.05). Patients with lumbar fusion done via the anterior approach were more likely to have robotic-assisted surgery compared to other approaches (25.2% vs. 21.3; p < 0.05). Overall, there was a steady increase in its use over time, with patients who underwent lumbar fusion procedures four times more likely to receive robotic assistance in 2019 compared to 2016 (OR: 4.0; 95% CI: 3.5-4.6; p < 0.0001). Robotic-assisted lumbar fusion was associated with higher inpatient costs ($170,036.40 vs. $139,026.10; p < 0.0001) despite having equivalent length of stay (3.31 ± 2.6 vs.3.37 ± 2.6; p = 0.06).

CONCLUSION

Robotic-assisted lumbar fusion is on the rise. Patients who had private insurance, were diagnosed with spondylolisthesis, and who had lumbar fusion via the anterior approach were more likely to undergo lumbar fusion using robotic assistance.

The Impact of Computer-Assisted Navigation on Charges and Readmission in Patients Undergoing Posterior Cervical Fusion Surgery

STUDY DESIGN

Retrospective cohort study of 2016 Healthcare Cost and Utilization Project Nationwide Readmissions Database (NRD).

OBJECTIVE

The aim was to evaluate cost and outcomes associated with navigation use on posterior cervical fusion (PCF) surgery patients.

SUMMARY OF BACKGROUND DATA

Computer-assisted navigation systems demonstrate comparable outcomes with hardware placement and procedural speed compared with traditional techniques. Innovations in technology continue to improve surgeons' performance in complicated procedures, causing need to analyze the impact on patient care.

METHODS

The 2016 NRD was queried for patients with PCF surgery ICD-10 codes. Cost and readmission rates were compared with and without navigation. Nonelective cases and patients below 18 years of age were excluded. Univariate analysis on demographics, surgical data, and total charges was performed. Lastly, multivariate analysis was performed to assess navigation's impact on cost and postoperative outcomes.

RESULTS

A total of 11,834 patients were identified, with 137 (1.2%) patients undergoing surgery with navigation and 11,697 (98.8%) patients without. Average total charge was $131,939.47 and $141,270.1 for the non-navigation and navigation cohorts, respectively ( P =0.349). Thirty-day and 90-day readmission rates were not significantly lower in patients who received navigation versus those that did not ( P =0.087). This remained insignificant after adjusting for several variables, age above 65, sex, medicare status, mental health history, and comorbidities. The model adjusting for demographic and comorbidities maintained insignificant results of navigation being associated with decreased 30-day and 90-day readmissions ( P =0.079).

CONCLUSIONS

Navigation use in PCF surgery was not associated with increased cost, and patients operated on with navigation did not significantly have increased routine discharge or decreased 90-day readmission. As a result, future studies must continue to evaluate the cost-benefit of navigation use for cervical fusion surgery.

LEVEL OF EVIDENCE

Level III.

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.

Aortic Injury by Thoracic Pedicle Screw. When Is Aortic Repair Required? Literature Review and Three New Cases

PURPOSE

Aortic injury by pedicle screw is rare but can cause serious complications. It has not been clearly determined when aortic repair is necessary in cases of screw impingement without perforation of the aortic wall. In this article, we review the treatment and clinical course of pedicle screw aortic impingement and attempt to clarify this issue.

METHODS

Cases of aortic injury during thoracic screw procedures were found using a MEDLINE search and analyzed together with 3 new cases that we present.

RESULTS

Nineteen cases collected from the literature and 3 new cases were included in the study. In 7 of the cases, aortic impingement by the pedicle screw was detected during postoperative follow-up (day 1) radiologic examinations. In the other cases, time to presentation of aortic impingement ranged between 2 weeks and 60 months after fixation. The main indications for thoracic spinal fixation were post-traumatic vertebral fracture and kyphoscoliosis/scoliosis. Repair of the aortic damage ranged from primary repair to stent and tube graft placement by the thoracic endovascular aortic repair method.

CONCLUSIONS

In cases in which the screw impinges less than 5 mm into the aortic wall, hardware revision without aortic repair may be sufficient if recognized early and there are no sign of aortic leakage in vascular imaging. However, cases with more than 5 mm of screw impingement should undergo aortic repair first, even in the absence of aortic leakage, following by screw revision.

Radiation Exposure and Operation Time in Percutaneous Endoscopic Lumbar Discectomy Using Fluoroscopy-Based Navigation System

OBJECTIVE

This study evaluated radiation exposure and operation time of percutaneous endoscopic lumbar discectomy (PELD) by using a fluoroscopy-based navigation system for access and localization.

METHODS

Eighty-six PELDs performed by a single surgeon were retrospectively analyzed. Patients were separated into 2 groups: group A (using a three-dimensional [3D]-printed navigation instrument and fluoroscopy-based navigation system) and group B (with conventional fluoroscopy and standard instrumentation). The operation, fluoroscopy, and total access time were collected, as well as fluoroscopy and access times.

RESULTS

The operative time for group A was 59 minutes (standard deviation [SD], 6 minutes) and 106 minutes (SD, 15 minutes) in group B (P < 0.001). In group A, fluoroscopy was used an average of 5 times (SD, 0.7) and 29 times (SD, 8) in group B (P < 0.001). The fluoroscopy time was 9 minutes (SD, 2 minutes) in group A and 40 minutes (SD, 8 minutes) in group B (P < 0.001). The number of access attempts was 1.3 (SD, 0.5) in group A and 8 (SD, 2 times) in group B (P < 0.001). The total access time was 11 minutes (SD, 2 minutes) in group A and 28 minutes (SD, 5 minutes) in group B (P < 0.001).

CONCLUSIONS

PELD using the fluoroscopy-based navigation system showed lower operative, fluoroscopy, and access time compared with conventional techniques. In addition, fewer fluoroscopy images and access attempts were made in the navigation group. These data suggest that this novel technique reduces fluoroscopy and operation time and may reduce risks of repeated surgical access attempts.

Surgery for traumatic fractures of the upper thoracic spine (T1-T6)

Background:

The management of traumatic upper thoracic spine fractures (T1–T6) is complex due to the unique biomechanical/physiological characteristics of these levels and the nature of the injuries. They are commonly associated with multiple other traumatic injuries and severe spinal cord injuries. We describe the safety and efficacy of surgery for achieving stability and maintaining reduction of upper thoracic T1–T6 spine fractures.

Methods:

We retrospectively analyzed a series of traumatic unstable upper thoracic (T1–T6) spine fractures treated at one institution between 1993 and 2016. All patients were assessed neurologically and underwent complete preoperative radiographic analysis of their T1–T6 spine fractures including assessment of instability. Neurological and radiographic outcomes including fusion rates, kyphotic deformity, and successful reduction of the fracture were evaluated along with hospital length of stay (LOS), intensive care unit LOS, and overall complication rates.

Results:

There were 43 patients (29 males, 14 females) with an average age of 37.7 years. Between 1993 and 1999, 8 patients were treated with hook/rod constructs, whereas between 1995 and 2016, 35 patients received pedicle screw fixation utilizing intraoperative fluoroscopy or computed tomography (CT) navigation. Forty-three patients had a total of 178 levels fused. In this series, there were no intraoperative vascular or neurological complications. Instrumentation was removed in five patients due to pain, wound infection, or hardware failure. The mean hospital LOS was 21.1 days (range 4–59 days), and there was a 95% fusion rate based on follow-up imaging (X-rays or CT scan).

Conclusions:

Surgical treatment of upper thoracic spine fractures (T1–T6), although complex, is safe and effective. Reduction and fixation of these fractures decreases the risk of further neurological complications, allows for earlier mobilization, and correlates with shorter hospital LOS and improved outcomes.

Pediatric Lumbar Pedicle Screw Placement Using Navigation Templates: A Cadaveric Study

BACKGROUND

Pedicle screw technique is commonly used treatment of adult spinal trauma, tumor, degeneration. The application of pedicle screws is very challenging in children because children have a fast growing spine and spinal pedicle morphology of children and adult has large difference. 3 D reconstruction individual navigation templates improve the success rate of pediatric pedicle screw system. This study is aimed to provide a precise method for lumbar spine pedicle screw placement in children using computer-aided design and rapid prototyping technology.

MATERIALS AND METHODS

Computed tomography (CT) scans of cadaver specimens of 4 children were obtained, and the raw data were reconstructed using three-dimensional reconstruction software. Pedicle screws were placed using the conventional method or by using individually designed navigation templates based on the principles of reverse engineering and rapid prototyping technology.

RESULTS

We evaluated the accuracy of the pedicle screws placed using the two methods by CT scan. Ten navigation templates were designed for placement of 20 lumbar pedicle screws in the navigation group, and CT scan confirmed that all the screws were placed accurately in the corresponding pedicle. Conversely, of the 20 lumbar pedicle screws placed using the conventional method, 3 screws perforated the pedicle. The findings showed that lumbar pedicle screw placement was successful using navigation templates in children.

CONCLUSIONS

This technique is simple, easy to master, and allows personalized screw placement, thus providing a new and feasible method for lumbar pedicle screw placement in children.

Initial academic experience and learning curve with robotic spine instrumentation

OBJECTIVE

Spine surgery is complex and involves various steps. Current robotic technology is mostly aimed at assisting with pedicle screw insertion. This report evaluates the feasibility of robot-assisted pedicle instrumentation in an academic environment with the involvement of residents and fellows.

METHODS

The Renaissance Guidance System was used to plan and execute pedicle screw placement in open and percutaneous consecutive cases performed in the period of December 2015 to December 2016. The database was reviewed to assess the usability of the robot by neurosurgical trainees. Outcome measures included time per screw, fluoroscopy time, breached screws, and other complications. Screw placement was assessed in patients with postoperative CT studies. The speed of screw placement and fluoroscopy time were collected at the time of surgery by personnel affiliated with the robot’s manufacturer. Complication and imaging data were reviewed retrospectively.

RESULTS

A total of 306 pedicle screws were inserted in 30 patients with robot guidance. The average time for junior residents was 4.4 min/screw and for senior residents and fellows, 4.02 min/screw (p = 0.61). Among the residents dedicated to spine surgery, the average speed was 3.84 min/screw, while nondedicated residents took 4.5 min/screw (p = 0.41). Evaluation of breached screws revealed some of the pitfalls in using the robot.

CONCLUSIONS

No significant difference regarding the speed of pedicle instrumentation was detected between the operators’ years of experience or dedication to spine surgery, although more participants are required to investigate this completely. On the other hand, there was a trend toward improved efficiency with more cases performed. To the authors’ knowledge, this is the first reported academic experience with robot-assisted spine instrumentation.

Differences between Manufacturers of Computed Tomography-Based Computer-Assisted Surgery Systems Do Exist: A Systematic Literature Review

STUDY DESIGN

Literature review.

OBJECTIVE

Several studies have shown that the accuracy of pedicle screw placement significantly improves with use of computed tomography (CT)-based navigation systems. Yet, there has been no systematic review directly comparing accuracy of pedicle screw placement between different CT-based navigation systems. The objective of this study is to review the results presented in the literature and compare CT-based navigation systems relative only to screw placement accuracy.

METHODS

Data sources included CENTRAL, Medline, PubMed, and Embase databases. Studies included were randomized clinical trials, case series, and case-control trials reporting the accuracy of pedicle screws placement using CT-based navigation. Two independent reviewers extracted the data from the selected studies that met our inclusion criteria. Publications were grouped based on the CT-based navigation system used for pedicle screw placement.

RESULTS

Of the 997 articles we screened, only 26 met all of our inclusion criteria and were included in the final analysis, which showed a significant statistical difference (p < 0.0001, 95% confidence interval 0.92 to 1.23) in accuracy of pedicle screw placement between three different CT-based navigation systems. The mean (weighted) accuracy of pedicle screws placement based on the CT-based navigation system was found to be 97.20 ± 2.1% in StealthStation (Medtronic, United States) and 96.1 ± 3.9% in VectorVision (BrainLab, Germany).

CONCLUSION

This review summarizes results presented in the literature and compares screw placement accuracy using different CT-based navigation systems. Although certain factors such as the extent of the procedure and the experience and skills of the surgeon were not accounted for, the differences in accuracy demonstrated should be considered by spine surgeons and should be validated for effects on patients' outcome.

[Rigid cystoscopy versus retrovision for adjustable peri-urethral balloons guidance: Comparison of precision thanks to a surgical navigation system]

OBJECTIVES

The main goal of our phantom study was to compare the precision of adjustable periurethral balloons positioning depending whether the guidance was obtained by retrovision or rigid cystoscopy.

MATERIAL AND METHODS

A navigation guidance system was used to localize the introduction mandrel which was equipped with tracking targets. Two ideal sites of implantation were predefined and recorded into the navigation system. The two points were placed symmetrically to the phantom reproducing the urethra. Four different users were asked to position the tip of the introduction mandrel as close as possible to the ideal site of implantation with the help of each method of guidance. For each attempt, the distance (mm) between the tip of the introduction mandrel and the ideal position was recorded by the navigation system.

RESULTS

For each method of guidance, a total of 20 attempts on each side were made by direct puncture on one side and a symmetrical contralateral puncture. For direct puncture, the median distances were 5.20 (±3.96) and 4.38 (±1.55) mm with rigid cystoscopy and retrovision respectively (P=0.29). For symmetrical contralateral puncture, the median distance were 7,19 (±3,78) and 6,86 (±2,76) mm with rigid cystoscopy and retrovision respectively (P=0,32) CONCLUSION: This study could not demonstrate any significant difference between the two guidance systems. Nevertheless, it showed that navigation guidance system could be used to compare the precision of surgical interventions.

LEVEL OF EVIDENCE

4.

Burden of disease of reoperations in instrumental spinal surgeries in Germany

PURPOSE

To estimate the incidence of instrumental spinal surgeries (ISS) and consecutive reoperations and to calculate the related resource utilization and costs.

METHODS

ISS and subsequent reoperations were identified retrospectively using surgery codes in claims data. The study period included January 01, 2009 to December 31, 2011. The reoperation rate was calculated for 1 year after the primary ISS. Resource utilization and costs were analyzed by group comparison.

RESULTS

A total of 3316 incident ISS patients were identified in 2010 with an annual reoperation rate of 9.98% (95% CI 8.98-11.02%). Mean costs per patient were €11,331 per ISS and €11,370 per reoperation, with €8432 directly attributed to the reoperation and €2938 to additional resources.

CONCLUSIONS

Costs of ISS and subsequent reoperations have a significant impact on health insurances budgets. The annual cost of reoperations exceeds the direct cost of the primary surgery driven by the need for further inpatient and outpatient care.

Assessment of pedicle screw placement accuracy in thoracolumbosacral spine using freehand technique aided by lateral fluoroscopy: results of postoperative computed tomography in 114 patients

BACKGROUND CONTEXT

Pedicle screw fixation is currently widely used in spine surgery for various pathologies. Increasing screw placement accuracy would improve the outcomes.

PURPOSE

To determine the accuracy rate of screw placement in a group of patients who underwent pedicle screw fixation with conventional techniques.

STUDY DESIGN

A case series.

PATIENT SAMPLE

It includes patients undergoing posterior spinal fixation with pedicle screw insertion. Outcome measures include the accuracy of screw placement in pedicles defined by postoperative computed tomography (CT).

METHODS

After surgery, an axial thin-cut CT scan was performed in all patients. Screw position was classified as correct when the screw was completely surrounded by the pedicle cortex and incorrect when any part of the screw was outside the pedicle boundaries.

RESULTS

Seven hundred seventy screws were inserted at vertebral levels T7-S1 of 114 patients between March 2012 and December 2012. There were three wound infections and one death. Eighteen screws were diagnosed as having an incorrect position (2.3%). The highest accuracy was observed in levels L4 and L5 (0.8% inaccuracy rate for each), whereas the highest inaccuracy rate was observed in T9. The mean inaccuracy rate was 10.5% for levels T7-T9, 3.5% for levels T10-L2, and 0.9% for levels L3-S1. The differences were statistically significant. Only one screw (5%) needed revision.

CONCLUSIONS

The results of our study show that conventional methods for pedicle screw placement remain safe and accurate, with best results obtained in the lumbosacral spine, followed by the thoracolumbar junction. Nonetheless, results are less accurate in the midthoracic spine.

The evolution of image-guided lumbosacral spine surgery

Techniques and approaches of spinal fusion have considerably evolved since their first description in the early 1900s. The incorporation of pedicle screw constructs into lumbosacral spine surgery is among the most significant advances in the field, offering immediate stability and decreased rates of pseudarthrosis compared to previously described methods. However, early studies describing pedicle screw fixation and numerous studies thereafter have demonstrated clinically significant sequelae of inaccurate surgical fusion hardware placement. A number of image guidance systems have been developed to reduce morbidity from hardware malposition in increasingly complex spine surgeries. Advanced image guidance systems such as intraoperative stereotaxis improve the accuracy of pedicle screw placement using a variety of surgical approaches, however their clinical indications and clinical impact remain debated. Beginning with intraoperative fluoroscopy, this article describes the evolution of image guided lumbosacral spinal fusion, emphasizing two-dimensional (2D) and three-dimensional (3D) navigational methods.

Navigated pedicle screw placement using computed tomographic data in dorsolumbar fractures

BACKGROUND

Computed tomographic (CT) based navigation is a technique to improve the accuracy of pedicle screw placement. It is believed to enhance accuracy of pedicle screw placement, potentially avoiding complications arising due to pedicle wall breach. This study aims to assess the results of dorsolumbar fractures operated by this technique.

MATERIALS AND METHODS

Thirty consecutive skeletally mature patients of fractures of dorsolumbar spine (T9-L5) were subjected to an optoelectronic navigation system. All patients were thoroughly examined for neurological deficit. The criterion for instability were either a tricolumnar injury or presence of neurological deficit or both. Patients with multilevel fractures and distorted spine were excluded from study. Time taken for insertion of each pedicle screw was recorded and placement assessed with a postoperative CT scan using Laine's grading system.

RESULTS

Only one screw out of a total of 118 screws was misplaced with a Laine's Grade 5 placement, showing a misplacement rate of 0.847%. Average time for matching was 7.8 min (range 5-12 min). Average time taken for insertion of a single screw was 4.19 min (range 2-8 min) and total time for all screws after exposure was 34.23 min (range 24-45 min) for a four screw construct. No neurovascular complications were seen in any of the patients postoperatively and in subsequent followup of 1-year duration.

CONCLUSION

CT-based navigation is effective in improving accuracy of pedicle screw placement in traumatic injuries of dorsolumbar spine (T9-L5), however additional cost of procuring CT scan to the patient and cost of equipment is of significant concern in developing countries. Reduced radiation exposure and lowered ergonomic constraints around the operation table are its additional benefits.

Position and complications of pedicle screw insertion with or without image-navigation techniques in the thoracolumbar spine: a meta-analysis of comparative studies

Computer-navigated pedicle screw insertion is applied to the thoracic and lumbar spine to attain high insertion accuracy and a low rate of screw-related complications. However, some in vivo and in vitro studies have shown that no advantages are gained with the use of navigation techniques compared to conventional techniques. Additionally, inconsistent conclusions have been drawn in various studies due to different population characteristics and methods used to assess the accuracy of screw placement. Moreover, it is not clear whether pedicle screw insertion with navigation techniques decreases the incidence of screw-related complications. Therefore, this study was sought to perform a meta-analysis of all available prospective evidence regarding pedicle screw insertion with or without navigation techniques in human thoracic and lumbar spine. We considered in vivo comparative studies that assessed the results of pedicle screw placement with or without navigation techniques. PubMed, Ovid MEDLINE and EMBASE databases were searched. Three published randomized controlled trials (RCTs) and nine retrospective comparative studies met the inclusion criteria. These studies included a total of 732 patients in whom 4,953 screws were inserted. In conclusion, accuracy of the position of grade I, II, III and IV screws and complication rate related to pedicle screw placement were significantly increased when navigation techniques were used in comparison to conventional techniques. Future research in this area should include RCTs with well-planned methodology to limit bias and report on validated, patient-based outcome measures.

Navigation, robotics, and intraoperative imaging in spinal surgery

Spinal navigation is a technique gaining increasing popularity. Different approaches as CT-based or intraoperative imaging-based navigation are available, requiring different methods of patient registration, bearing certain advantages and disadvantages. So far, a large number of studies assessed the accuracy of pedicle screw implantation in the cervical, thoracic, and lumbar spine, elucidating the advantages of image guidance. However, a clear proof of patient benefit is missing, so far. Spinal navigation is closely related to intraoperative 3D imaging providing an imaging dataset for navigational use and the opportunity for immediate intraoperative assessment of final screw position giving the option of immediate screw revision if necessary. Thus, postoperative imaging and a potential revision surgery for screw correction become dispensable.Different concept of spinal robotics as the DaVinci system and SpineAssist are under investigation.

Navigation-assisted surgery for tumors of the spine

PURPOSE

Computer-assisted navigation systems are largely used for pedicle screws positioning in degenerative and traumatic spine surgery. In oncologic spine surgery its use is still developing and could be extended for tumor identification and excision. Aim of this paper is to present our experience.

METHODS

Seven selected patients (5 females, 2 males), mean age 44 years (min 17-max 62) affected by primary benign or malignant tumors of the spine or spine metastases were surgically treated with the use of computer-assisted navigation system from March to October 2011.

RESULTS

At 18 months mean F.U. (min 15-max 23), no LR were observed. Revision surgery was necessary only in one case for C1 pedicle screw malpositioning.

CONCLUSIONS

Navigation system can improve surgical accuracy in screws placement and tumor localization and excision. Learning curve and technical aspects must be considered to avoid potential serious mistakes.

Accuracy of lower cervical pedicle screw placement with assistance of distinct navigation systems: a human cadaveric study

PURPOSE

Evaluate the accuracy of five different techniques for lower cervical pedicle screw placement.

METHODS

Forty human cadaveric cervical spines were equally divided into five groups, and each group had eight specimens. Pedicle screws with dia. 3.5 mm were used. Group 1 was blind screw placement without any assistance; Group 2-5 was assisted by the X-ray fluoroscopy, virtual fluoroscopy navigation system, CT-based navigation system, and Iso-C 3D navigation system, respectively. Thereafter, cortical integrity of each pedicle was evaluated by anatomic dissection of the specimens.

RESULTS

A total of 398 pedicle screws were inserted. In the Group 1-5, the average operation time per sample was 27 ± 3.0, 112 ± 10.3, 69 ± 6.4, 98 ± 11.0, and 91 ± 6.0 min, respectively. The outcome for excellent, fair and poor were 29 (36.3 %), 21 (26.2 %) and 30 (37.5 %) in Group 1; 35 (44.9 %), 29 (37.2 %) and 14 (17.9 %) in Group 2; 34 (42.5 %), 36 (45.0 %) and 10 (12.5 %) in Group 3; 70 (87.5 %), 10 (12.5 %) and 0 (0.0 %) in Group 4; 72 (90.0 %), 8 (10.0 %) and 0 (0.0 %) in Group 5.

CONCLUSIONS

Blind screw placement was surely unsafe. Lower cervical pedicle screw placement assisted by the CT-based navigation system or the Iso-C 3D navigation system significantly improved the accuracy compared to the fluoroscopy assistance and the virtual fluoroscopy navigation assistance.

Use of a quantitative pedicle screw accuracy system to assess new technology: Initial studies on O-arm navigation and its effect on the learning curve of percutaneous pedicle screw insertion

Background

A quantitative screw accuracy system is proposed that allows for high-fidelity discrimination between various methods of pedicle screw insertion. Our purpose was to study the utility of a quantitative screw accuracy scoring system to assess new imaging technologies and their effects on the minimally invasive spine learning curve.

Methods

By use of a hypothetical “perfect screw,” a scoring system is proposed that may be used to compare the position of a small number of screws inserted according to a desired optimal position. This study incorporates a retrospective review of imaging studies for 10 patients who underwent percutaneous pedicle screw placement with either navigation-assisted O-arm imaging or navigation-assisted C-arm imaging. For the learning-curve portion of the study, 2 cadaveric adult torsos were used for instrumentation. Computed tomography imaging studies were used in both studies to assess screw position in the pedicle and vertebral body in relation to an optimal screw by use of a quantitative scoring system to rate accuracy.

Results

The quantitative scoring system allowed a statistically significant accuracy difference to be ascertained between 2 different technologies using fewer data points than previously published methods. When this screw scoring system is applied to minimally invasive percutaneous pedicle screw insertion, an optimal screw position can be achieved with greater accuracy through navigation-assisted technology (O-arm with computer-assisted navigation). When the O-arm with computer-assisted navigation was used by a novice surgeon learning the technique of percutaneous screw insertion, screws were inserted in a shorter period without loss of accuracy. In contrast, use of the traditional C-arm fluoroscopy leads to a loss of accuracy with faster insertion times. Increased accuracy can be seen clinically when compared with fluoroscopic navigation.

Conclusions

The use of a quantitative scoring system allows for rapid assessment of screw accuracy. As additional technologies and new teaching techniques for pedicle screw insertion are developed, this scoring system may be useful as an early assessment tool.