Pedicle Screw Revision in Robot-Guided, Navigated, and Freehand Thoracolumbar Instrumentation: A Systematic Review and Meta-Analysis

Accuracy of Thoracolumbar Pedicle Screw Insertion Based on Routine Use of Intraoperative Imaging and Navigation

Study Design

Retrospective review.

Purpose

To determine the accuracy of thoracolumbar pedicle screw insertion with the routine use of three-dimensional (3D) intraoperative imaging and navigation over a large series of screws in an Asian population.

Overview of Literature

The use of 3D intraoperative imaging and navigation in spinal surgery is aimed at improving the accuracy of pedicle screw insertion. This study analyzed 2,240 pedicle screws inserted with the routine use of intraoperative navigation. It is one of very few studies done on an Asian population with a large series of screws.

Methods

Patients who had undergone thoracolumbar pedicle screws insertion using intraoperative imaging and navigation between 2009 and 2017 were retrospectively analyzed. Computed tomography (CT) images acquired after the insertion of pedicle screws were analyzed for breach of the pedicle wall. The pedicle screw breaches were graded according to the Gertzbein classification. The breach rate and revision rate were subsequently calculated.

Results

A total of 2,240 thoracolumbar pedicle screws inserted under the guidance of intraoperative navigation were analyzed, and the accuracy of the insertion was 97.41%. The overall breach rate was 2.59%, the major breach rate was 0.94%, and the intraoperative screw revision rate was 0.7%. There was no incidence of return to the operating theater for revision of screws.

Conclusions

The routine use of 3D navigation and intraoperative CT imaging resulted in consistently accurate pedicle screw placement. This improved the safety of spinal instrumentation and helped in avoiding revision surgery for malpositioned screws.

Robotic spine surgery: a review of the present status

With technological advancements being introduced and dominating many fields, spine surgery is no exception. In view of the patient safety and surgeon's comfort, robotics has been introduced in spine surgery. Due to small corridors for work, little room for inaccuracy, lengthy and tedious procedures, spine surgery is an ideal scenario for robotics to establish as the standard of care. Spine robotics received their first FDA clearance in 2004. New generation of spine robotics with integrated navigation systems has become available now. The primary role of spine robotics, at present, is to aid pedicle screw fixation. High quality studies have been performed to establish its role in increasing the accuracy of pedicle fixation. Studies have also reported decreased radiation and decreased operative time with spine robotics. However, few studies have reported otherwise. It is still in its nascent stage in both industrial view and surgeon familiarity. Continued research to overcome the challenges such as high cost and steep learning curve is crucial for its widespread use. Also, expanding the scope of spine robotics beyond pedicle screw fixation such as osteotomies and dural procedures would be an area for potential research. This review is intended to provide an overview of various studies in the field of robotic spine surgery and its present status.

Does Augmented Reality Navigation Increase Pedicle Screw Density Compared to Free-Hand Technique in Deformity Surgery? Single Surgeon Case Series of 44 Patients

STUDY DESIGN

Retrospective comparison between an interventional and a control cohort.

OBJECTIVE

The aim of this study was to investigate whether the use of an augmented reality surgical navigation (ARSN) system for pedicle screw (PS) placement in deformity cases could alter the total implant density and PS to hook ratio compared to free-hand (FH) technique.

SUMMARY OF BACKGROUND DATA

Surgical navigation in deformity surgery provides the possibility to place PS in small and deformed pedicles were hooks would otherwise have been placed, and thereby achieve a higher screw density in the constructs that may result in better long-term patient outcomes.

METHODS

Fifteen deformity cases treated with ARSN were compared to 29 cases treated by FH. All surgeries were performed by the same orthopedic spine surgeon. PS, hook, and combined implant density were primary outcomes. Procedure time, deformity correction, length of hospital stay, and blood loss were secondary outcomes. The surgeries in the ARSN group were performed in a hybrid operating room (OR) with a ceiling-mounted robotic C-arm with integrated video cameras for AR navigation. The FH group was operated with or without fluoroscopy as deemed necessary by the surgeon.

RESULTS

Both groups had an overall high-density construct (>80% total implant density). The ARSN group, had a significantly higher PS density, 86.3% ± 14.6% versus 74.7% ± 13.9% in the FH group (P < 0.05), whereas the hook density was 2.2% ± 3.0% versus 9.7% ± 9.6% (P < 0.001). Neither the total procedure time (min) 431 ± 98 versus 417 ± 145 nor the deformity correction 59.3% ± 16.6% versus 60.1% ± 17.8% between the groups were significantly affected.

CONCLUSION

This study indicates that ARSN enables the surgeon to increase the PS density and thereby minimize the use of hooks in deformity surgery without prolonging the OR time. This may result in better constructs with possible long-term advantage and less need for revision surgery.

LEVEL OF EVIDENCE

3.

Accuracy of robot-assisted versus conventional freehand pedicle screw placement in spine surgery: a systematic review and meta-analysis of randomized controlled trials

This systematic review and meta-analysis investigated differences in accuracy, operation time, and radiation exposure time between robot-assisted and freehand techniques for pedicle screw insertion. Two investigators independently searched for articles on randomized controlled trials (RCTs) published from 2012 to 2019. The final meta-analysis included seven RCTs. We compared the accuracy of pedicle screw placement, operation time, and radiation exposure time between robot-assisted and conventional freehand groups. Seven RCTs included 540 patients and placement of 2,476 pedicle screws, of which 1,220 were inserted using the robot-assisted technique and 1,256 were inserted using the conventional freehand technique. The pedicle screw positions were classified using the Gertzbein and Robbins classification (grade A-E). The combined results of Grade A [odds ratio (OR) =1.68; 95% confidence intervals (CI): 0.82-3.44; P=0.16), Grade A+B (OR =1.70; 95% CI: 0.47-6.13; P=0.42), and Grade C+D+E (OR =0.59; 95% CI: 0.16-2.12; P=0.42) for the accuracy rate revealed no significant difference between the two groups. Subgroup analysis results revealed that the TiRobot-assisted technique presented a significantly improved pedicle screw insertion accuracy rate compared with that of the conventional freehand technique, based on Grade A, Grade A+B, and Grade C+D+E classifications. The SpineAssist-assisted technique presented an inferior pedicle screw insertion accuracy rate compared with that of the conventional freehand technique, based on Grade A, Grade A+B, and Grade C+D+E classifications. No difference between the Renaissance-assisted and conventional freehand techniques was noted for pedicle screw insertion accuracy rates, based on both Grade A (OR =1.58; 95% CI: 0.85-2.96; P=0.15), Grade A+B (OR =2.20; 95% CI: 0.39-12.43; P=0.37), and Grade C+D+E (OR =0.45; 95% CI: 0.08-2.56; P=0.37) classifications. Regarding operation time, robot-assisted surgery had significantly longer operation time than conventional freehand surgery. The robot-assisted group had significantly shorter radiation exposure time. Regarding the pedicle screw insertion accuracy rate, the TiRobot-assisted technique was superior, the SpineAssist-assisted technique was inferior, and Renaissance was similar to the conventional freehand technique.

Diffuse reflectance spectroscopy for breach detection during pedicle screw placement: a first in vivo investigation in a porcine model

Background

The safe and accurate placement of pedicle screws remains a critical step in open and minimally invasive spine surgery, emphasizing the need for intraoperative guidance techniques. Diffuse reflectance spectroscopy (DRS) is an optical sensing technology that may provide intraoperative guidance in pedicle screw placement.

Purpose

The study presents the first in vivo minimally invasive procedure using DRS sensing at the tip of a Jamshidi needle with an integrated optical K-wire. We investigate the effect of tissue perfusion and probe-handling conditions on the reliability of fat fraction measurements for breach detection in vivo.

Methods

A Jamshidi needle with an integrated fiber-optic K-wire was gradually inserted into the vertebrae under intraoperative image guidance. The fiber-optic K-wire consisted of two optical fibers with a fiber-to-fiber distance of 1.024 mm. DRS spectra in the wavelength range of 450 to 1600 nm were acquired at several positions along the path inside the vertebrae. Probe-handling conditions were varied by changing the amount of pressure exerted on the probe within the vertebrae. Continuous spectra were recorded as the probe was placed in the center of the vertebral body while the porcine specimen was sacrificed via a lethal injection.

Results

A typical insertion of the fiber-optic K-wire showed a drop in fat fraction during an anterior breach as the probe transitioned from cancellous to cortical bone. Fat fraction measurements were found to be similar irrespective of the amount of pressure exerted on the probe (p = 0.65). The 95% confidence interval of fat fraction determination was found in the narrow range of 1.5–3.6% under various probe-handling conditions. The fat fraction measurements remained stable during 70 min of decreased blood flow after the animal was sacrificed.

Discussions

These findings indicate that changes in tissue perfusion and probe-handling conditions have a relatively low measureable effect on the DRS signal quality and thereby on the determination of fat fraction as a breach detection signal.

Conclusions

Fat fraction quantification for intraoperative pedicle screw breach detection is reliable, irrespective of changes in tissue perfusion and probe-handling conditions.

Role of Robotics in Improving Surgical Outcome in Spinal Pathologies

BACKGROUND

The desire to improve accuracy and safety and to favor minimally invasive techniques has given rise to spinal robotic surgery, which has seen a steady increase in utilization in the past 2 decades. However, spinal surgery encompasses a large spectrum of operative techniques, and robotic surgery currently remains confined to assistance with the trajectory of pedicle screw insertion, which has been shown to be accurate and safe based on class II and III evidence. The role of robotics in improving surgical outcomes in spinal pathologies is less clear, however.

METHODS

This comprehensive review of the literature addresses the role of robotics in surgical outcomes in spinal pathologies with a focus on the various meta-analysis and prospective randomized trials published within the past 10 years in the field.

RESULTS

It appears that robotic spinal surgery might be useful for increasing accuracy and safety in spinal instrumentation and allows for a reduction in surgical time and radiation exposure for the patient, medical staff, and operator.

CONCLUSION

Robotic assisted surgery may thus open the door to minimally invasive surgery with greater security and confidence. In addition, the use of robotics facilitates tireless repeated movements with higher precision compared with humans. Nevertheless, it is clear that further studies are now necessary to demonstrate the role of this modern tool in cost-effectiveness and in improving clinical outcomes, such as reoperation rates for screw malpositioning.

Augmented reality-based navigation increases precision of pedicle screw insertion

Background

Precise insertion of pedicle screws is important to avoid injury to closely adjacent neurovascular structures. The standard method for the insertion of pedicle screws is based on anatomical landmarks (free-hand technique). Head-mounted augmented reality (AR) devices can be used to guide instrumentation and implant placement in spinal surgery. This study evaluates the feasibility and precision of AR technology to improve precision of pedicle screw insertion compared to the current standard technique.

Methods

Two board-certified orthopedic surgeons specialized in spine surgery and two novice surgeons were each instructed to drill pilot holes for 40 pedicle screws in eighty lumbar vertebra sawbones models in an agar-based gel. One hundred and sixty pedicles were randomized into two groups: the standard free-hand technique (FH) and augmented reality technique (AR). A 3D model of the vertebral body was superimposed over the AR headset. Half of the pedicles were drilled using the FH method, and the other half using the AR method.

Results

The average minimal distance of the drill axis to the pedicle wall (MAPW) was similar in both groups for expert surgeons (FH 4.8 ± 1.0 mm vs. AR 5.0 ± 1.4 mm, p = 0.389) but for novice surgeons (FH 3.4 mm ± 1.8 mm, AR 4.2 ± 1.8 mm, p = 0.044).

Expert surgeons showed 0 primary drill pedicle perforations (PDPP) in both the FH and AR groups. Novices showed 3 (7.5%) PDPP in the FH group and one perforation (2.5%) in the AR group, respectively (p > 0.005).

Experts showed no statistically significant difference in average secondary screw pedicle perforations (SSPP) between the AR and the FH set 6-, 7-, and 8-mm screws (p > 0.05). Novices showed significant differences of SSPP between most groups: 6-mm screws, 18 (45%) vs. 7 (17.5%), p = 0.006; 7-mm screws, 20 (50%) vs. 10 (25%), p = 0.013; and 8-mm screws, 22 (55%) vs. 15 (37.5%), p = 0.053, in the FH and AR group, respectively. In novices, the average optimal medio-lateral convergent angle (oMLCA) was 3.23° (STD 4.90) and 0.62° (STD 4.56) for the FH and AR set screws (p = 0.017), respectively. Novices drilled with a higher precision with respect to the cranio-caudal inclination angle (CCIA) category (p = 0.04) with AR.

Conclusion

In this study, the additional anatomical information provided by the AR headset superimposed to real-world anatomy improved the precision of drilling pilot holes for pedicle screws in a laboratory setting and decreases the effect of surgeon’s experience. Further technical development and validations studies are currently being performed to investigate potential clinical benefits of the herein described AR-based navigation approach.

Feasibility and accuracy of a robotic guidance system for navigated spine surgery in a hybrid operating room: a cadaver study

The combination of navigation and robotics in spine surgery has the potential to accurately identify and maintain bone entry position and planned trajectory. The goal of this study was to examine the feasibility, accuracy and efficacy of a new robot-guided system for semi-automated, minimally invasive, pedicle screw placement. A custom robotic arm was integrated into a hybrid operating room (OR) equipped with an augmented reality surgical navigation system (ARSN). The robot was mounted on the OR-table and used to assist in placing Jamshidi needles in 113 pedicles in four cadavers. The ARSN system was used for planning screw paths and directing the robot. The robot arm autonomously aligned with the planned screw trajectory, and the surgeon inserted the Jamshidi needle into the pedicle. Accuracy measurements were performed on verification cone beam computed tomographies with the planned paths superimposed. To provide a clinical grading according to the Gertzbein scale, pedicle screw diameters were simulated on the placed Jamshidi needles. A technical accuracy at bone entry point of 0.48 ± 0.44 mm and 0.68 ± 0.58 mm was achieved in the axial and sagittal views, respectively. The corresponding angular errors were 0.94 ± 0.83° and 0.87 ± 0.82°. The accuracy was statistically superior (p < 0.001) to ARSN without robotic assistance. Simulated pedicle screw grading resulted in a clinical accuracy of 100%. This study demonstrates that the use of a semi-automated surgical robot for pedicle screw placement provides an accuracy well above what is clinically acceptable.

Conventional versus stereotactic image guided pedicle screw placement during spinal deformity correction: a retrospective propensity score-matched study of a national longitudinal database

PURPOSE/AIM

To compare complications, readmissions, revisions, and payments between navigated and conventional pedicle screw fixation for treatment of spine deformity.

METHODS

The Thomson Reuters MarketScan national longitudinal database was used to identify patients undergoing osteotomy, posterior instrumentation, and fusion for treatment of spinal deformity with or without image-guided navigation between 2007-2016. Conventional and navigated groups were propensity-matched (1:1) to normalize differences between demographics, comorbidities, and surgical characteristics. Clinical outcomes and charges were compared between matched groups using bivariate analyses.

RESULTS

A total of 4,604 patients were identified as having undergone deformity correction, of which 286 (6.2%) were navigated. Propensity-matching resulted in a total of 572 well-matched patients for subsequent analyses, of which half were navigated. Rate of mechanical instrumentation-related complications was found to be significantly lower for navigated procedures (p = 0.0371). Navigation was also associated with lower rates of 90-day unplanned readmissions (p = 0.0295), as well as 30- and 90-day postoperative revisions (30-day: p = 0.0304, 90-day: p = 0.0059). Hospital, physician, and total payments favored the conventional group for initial admission (p = 0.0481, 0.0001, 0.0019, respectively); however, when taking into account costs of readmissions, hospital payments became insignificantly different between the two groups.

CONCLUSIONS

Procedures involving image-guided navigation resulted in decreased instrumentation-related complications, unplanned readmissions, and postoperative revisions, highlighting its potential utility for the treatment of spine deformity. Future advances in navigation technologies and methodologies can continue to improve clinical outcomes, decrease costs, and facilitate widespread adoption of navigation for deformity correction.

A Review of Techniques, Time Demand, Radiation Exposure, and Outcomes of Skin-anchored Intraoperative 3D Navigation in Minimally Invasive Lumbar Spinal Surgery

STUDY DESIGN

Retrospective cohort.

OBJECTIVE

To describe our technique for and evaluate the time demand, radiation exposure and outcomes of skin-anchored intraoperative three-dimensional navigation (ION) in minimally invasive (MIS) lumbar surgery, and to compare these parameters to 2D fluoroscopy for MI-TLIF.

SUMMARY OF BACKGROUND DATA

Limited visualization of anatomic landmarks and narrow access corridor in MIS procedures result in greater reliance on image guidance. Although two-dimensional fluoroscopy has historically been used, ION is gaining traction.

METHODS

Patients who underwent MIS lumbar microdiscectomy, laminectomy, or MI-TLIF using skin-anchored ION and MI-TLIF by the same surgeon using 2D fluoroscopy were selected. Operative variables, radiation exposure, and short-term outcomes of all procedures were summarized. Time-demand and radiation exposure of fluoroscopy and ION for MI-TLIF were compared.

RESULTS

Of the 326 patients included, 232 were in the ION cohort (92 microdiscectomies, 65 laminectomies, and 75 MI-TLIFs) and 94 in the MI-TLIF using 2D fluoroscopy cohort. Time for ION setup and image acquisition was a median of 22 to 24 minutes. Total fluoroscopy time was a median of 10 seconds for microdiscectomy, 9 for laminectomy, and 26 for MI-TLIF. Radiation dose was a median of 15.2 mGy for microdiscectomy, 16.6 for laminectomy, and 44.6 for MI-TLIF, of this, 93%, 95%, and 37% for microdiscectomy, laminectomy, and MI-TLIF, respectively were for ION image acquisition, with the rest attributable to the procedure. There were no wrong-level surgeries. Compared with fluoroscopy, ION for MI-TLIF resulted in lower operative times (92 vs. 108 min, P < 0.0001), fluoroscopy time (26 vs. 144 s, P < 0.0001), and radiation dose (44.6 vs. 63.1 mGy, P = 0.002), with equivalent time-demand and length of stay. ION lowered the radiation dose by 29% for patients and 55% for operating room personnel.

CONCLUSION

Skin-anchored ION does not increase time-demand compared with fluoroscopy, is feasible, safe and accurate, and results in low radiation exposure.

LEVEL OF EVIDENCE

3.

Evolving Navigation, Robotics, and Augmented Reality in Minimally Invasive Spine Surgery

Innovative technology and techniques have revolutionized minimally invasive spine surgery (MIS) within the past decade. The introduction of navigation and image-guided surgery has greatly affected spinal surgery and will continue to make surgery safer and more efficient. Eventually, it is conceivable that fluoroscopy will be completely replaced with image guidance. These advancements, among others such as robotics and virtual and augmented reality technology, will continue to drive the value of 3-dimensional navigation in MIS. In this review, we cover pertinent features of navigation in MIS and explore their evolution over time. Moreover, we aim to discuss the key features germane to surgical advancement, including technique and technology development, accuracy, overall health care costs, operating room time efficiency, and radiation exposure.

Comparison of Superior-Level Facet Joint Violations Between Robot-Assisted Percutaneous Pedicle Screw Placement and Conventional Open Fluoroscopic-Guided Pedicle Screw Placement

Objective

To compare the superior‐level facet joint violations (FJV) between robot‐assisted (RA) percutaneous pedicle screw placement and conventional open fluoroscopic‐guided (FG) pedicle screw placement in a prospective cohort study.

Methods

This was a prospective cohort study without randomization. One‐hundred patients scheduled to undergo RA (n = 50) or FG (n = 50) transforaminal lumbar interbody fusion were included from February 2016 to May 2018. The grade of FJV, the distance between pedicle screws and the corresponding proximal facet joint, and intra‐pedicle accuracy of the top screw were evaluated based on postoperative CT scan. Patient demographics, perioperative outcomes, and radiation exposure were recorded and compared. Perioperative outcomes include surgical time, intraoperative blood loss, postoperative length of stay, conversion, and revision surgeries.

Results

Of the 100 screws in the RA group, 4 violated the proximal facet joint, while 26 of 100 in the FG group had FJV (P = 0.000). In the RA group, 3 and 1 screws were classified as grade 1 and 2, respectively. Of the 26 FJV screws in the FG group, 17 screws were scored as grade 1, 6 screws were grade 2, and 3 screws were grade 3. Significantly more severe FJV were noted in the FG group than in the RA group (P = 0.000). There was a statistically significant difference between RA and FG for overall violation grade (0.05 vs 0.38, P = 0.000). The average distance of pedicle screws from facet joints in the RA group (4.16 ± 2.60 mm) was larger than that in the FG group (1.92 ± 1.55 mm; P = 0.000). For intra‐pedicle accuracy, the rate of perfect screw position was greater in the RA group than in the FG group (85% vs 71%; P = 0.017). No statistically significant difference was found between the clinically acceptable screws between groups (P = 0.279). The radiation dose was higher in the FG group (30.3 ± 11.3 vs 65.3 ± 28.3 μSv; P = 0.000). The operative time in the RA group was significantly longer (184.7 ± 54.3 vs 117.8 ± 36.9 min; P = 0.000).

Conclusions

Compared to the open FG technique, minimally invasive RA spine surgery was associated with fewer proximal facet joint violations, larger facet to screw distance, and higher intra‐pedicle accuracy.

Robotic spine surgery: Ushering in a new era

The endeavour to make spine surgery safe with reproducible, consistent outcomes has led to growing interest and research in the field of intraoperative imaging, navigation and robotics. The advent of surgical robot systems in spine surgery is relatively recent - with only a few systems approved for commercial use. At present, pedicle screw insertion remains the primary application of robotic systems in spine surgery. The purported advantages of robot-assisted pedicle screw insertion over other conventional techniques are its increased accuracy, reproducible consistency and reduced radiation exposure. Many of these claims have been supported or refuted by individual studies - and high quality evidence for the same is lacking. Robotic spine surgery also has its share of limitations which include increased operative time, considerable learning curve and technical pitfalls unique to the robotic systems. The applications of robotic spine surgery are evolving and expanding to spinal deformity, spine oncology and needle-based interventional treatments. This review provides an overview of the evolution and current status of robotic spine surgery along with an evidence-based discussion of its current applications in spine surgery.

The Accuracy of 3D Printing Assistance in the Spinal Deformity Surgery

BACKGROUND

The pedicle screw is one of the main tools used in spinal deformity correction surgery. Robotic and navigated surgeries are usually used, and they provide superior accuracy in pedicle screw placement than free-hand and fluoroscopy-guided techniques. However, their high cost and space limitation are problematic. We provide a new solution using 3D printing technology to facilitate spinal deformity surgery.

METHODS

A workflow was developed to assist spinal deformity surgery using 3D printing technology. The trajectory and profile of pedicle screws were determined on the image system by the surgical team. The engineering team designed drill templates based on the bony surface anatomy and the trajectory of pedicle screws. Their effectiveness and safety were evaluated during a preoperative simulation surgery. The surgery consisted in making a pilot hole through the drill template on a computed tomography- (CT-) based, full-scale 3D spine model for every planned segment. Somatosensory evoke potential (SSEP) and motor evoke potential (MEP) were used for intraoperative neurophysiological monitoring. Postoperative CT was obtained 6 months after the correction surgery to confirm the screw accuracy.

RESULTS

From July 2015 to November 2016, we performed 10 spinal deformity surgeries with 3D printing technology assistance. In total, 173 pedicle screws were implanted using drill templates. No notable change in SSEP and MEP or neurologic deficit was noted. Based on postoperative CT scans, the acceptable rate was 97.1% (168/173). We recorded twelve pedicle screws with medial breach, six with lateral breach, and five with inferior breach. Medial breach (12/23) was the main type of penetration. Lateral breach occurred mostly in the concave side (5/6). Most penetrations occurred above the T8 level (69.6%, 16/23).

CONCLUSION

3D printing technology provides an effective alternative for spinal deformity surgery when expensive medical equipment, such as intraoperative navigation and robotic systems, is unavailable.

Conventional Versus Stereotactic Image-guided Pedicle Screw Placement During Posterior Lumbar Fusions: A Retrospective Propensity Score-matched Study of a National Longitudinal Database

STUDY DESIGN

Retrospective 1:1 propensity score-matched analysis on a national longitudinal database between 2007 and 2016.

OBJECTIVE

The aim of this study was to compare complication rates, revision rates, and payment differences between navigated and conventional posterior lumbar fusion (PLF) procedures with instrumentation.

SUMMARY OF BACKGROUND DATA

Stereotactic navigation techniques for spinal instrumentation have been widely demonstrated to improve screw placement accuracies and decrease perforation rates when compared to conventional fluoroscopic and free-hand techniques. However, the clinical utility of navigation for instrumented PLF remains controversial.

METHODS

Patients who underwent elective laminectomy and instrumented PLF were stratified into "single level" and "3- to 6-level" cohorts. Navigation and conventional groups within each cohort were balanced using 1:1 propensity score matching, resulting in 1786 navigated and conventional patients in the single-level cohort and 2060 in the 3 to 6 level cohort. Outcomes were compared using bivariate analysis.

RESULTS

For the single-level cohort, there were no significant differences in rates of complications, readmissions, revisions, and length of stay between the navigation and conventional groups. For the 3- to 6-level cohort, length of stay was significantly longer in the navigation group (P < 0.0001). Rates of readmissions were, however, greater for the conventional group (30-day: P = 0.0239; 90-day: P = 0.0449). Overall complications were also greater for the conventional group (P = 0.0338), whereas revision rate was not significantly different between the 2 groups. Total payments were significantly greater for the navigation group in both the single level and 3- to 6-level cohorts (P < 0.0001).

CONCLUSION

Although use of navigation for 3- to 6-level instrumented PLF was associated with increased length of stay and payments, the concurrent decreased overall complication and readmission rates alluded to its potential clinical utility. However, for single-level instrumented PLF, no differences in outcomes were found between groups, suggesting that the value in navigation may lie in more complex procedures.

LEVEL OF EVIDENCE

3.

The European Robotic Spinal Instrumentation (EUROSPIN) study: protocol for a multicentre prospective observational study of pedicle screw revision surgery after robot-guided, navigated and freehand thoracolumbar spinal fusion

INTRODUCTION

Robotic guidance (RG) and computer-assisted navigation (NV) have seen increased adoption in instrumented spine surgery over the last decade. Although there exists some evidence that these techniques increase radiological pedicle screw accuracy compared with conventional freehand (FH) surgery, this may not directly translate to any tangible clinical benefits, especially considering the relatively high inherent costs. As a non-randomised, expertise-based study, the European Robotic Spinal Instrumentation Study aims to create prospective multicentre evidence on the potential comparative clinical benefits of RG, NV and FH in a real-world setting.

METHODS AND ANALYSIS

Patients are allocated in a non-randomised, non-blinded fashion to the RG, NV or FH arms. Adult patients that are to undergo thoracolumbar pedicle screw instrumentation for degenerative pathologies, infections, vertebral tumours or fractures are considered for inclusion. Deformity correction and surgery at more than five levels represent exclusion criteria. Follow-up takes place at 6 weeks, as well as 12 and 24 months. The primary endpoint is defined as the time to revision surgery for a malpositioned or loosened pedicle screw within the first postoperative year. Secondary endpoints include patient-reported back and leg pain, as well as Oswestry Disability Index and EuroQOL 5-dimension questionnaires. Use of analgesic medication and work status are recorded. The primary analysis, conducted on the 12-month data, is carried out according to the intention-to-treat principle. The primary endpoint is analysed using crude and adjusted Cox proportional hazards models. Patient-reported outcomes are analysed using baseline-adjusted linear mixed models. The study is monitored according to a prespecified monitoring plan.

ETHICS AND DISSEMINATION

The study protocol is approved by the appropriate national and local authorities. Written informed consent is obtained from all participants. The final results will be published in an international peer-reviewed journal.

TRIAL REGISTRATION NUMBER

Clinical Trials.gov registry NCT03398915; Pre-results, recruiting stage.

Robotics in spinal surgery

Although the da Vinci robot system has garnered much attention in the realm of surgery over the past few decades, several new surgical robotic systems have been developed for spinal surgery with varying levels of robot autonomy and surgeon-specified input. These devices are currently being considered as potential avenues for increasing the precision of any surgical intervention. The following review will attempt to provide an overview of robotics in modern spine surgery and how these devices will continue to be employed in various sectors across the field.

Navigated robotic assistance results in improved screw accuracy and positive clinical outcomes: an evaluation of the first 54 cases

Computer-aided navigation and robotic guidance systems have become widespread in their utilization for spine surgery. A recent innovation combines these two advances, which theoretically provides accuracy in spinal screw placement. This study describes the cortical and pedicle screw accuracy for the first 54 cases where navigated robotic assistance was used in a surgical setting. This is a retrospective chart review of the initial 54 patients undergoing spine surgery with pedicle and cortical screws using robotic guidance with navigation. A computed tomography (CT)-based Gertzbein and Robbins System (GRS) was used to classify pedicle screw accuracy. Screw tip, tail, and angulation offsets were measured using image overlay analysis. Screw malposition, reposition, and return to operating room rates were collected. 1 of the first 54 cases was a revision surgery and was excluded from the study. Ten screws were placed without the robot due to surgeon discretion and were excluded for the data analysis of 292 screws. Only 0.68% (2/292) of the robot-assisted screws was repositioned based on surgeon discretion. Based on the GRS CT-based grading, 98.3% (287/292) were graded A or B, 1.0% (3/292) screws were graded C, and only 0.7% (2/292) screws was graded D. The average offset from preoperative plan to actual final placement was 1.9 mm from the tip, 2.3 mm from the tail, and 2.8° of angulation. In the first 53 cases, 292 screws placed with navigated robotic assistance resulted in a high level of accuracy (98.3%), adequate screw offsets from planned trajectory, and zero complications.

Validation of diffuse reflectance spectroscopy with magnetic resonance imaging for accurate vertebral bone fat fraction quantification

Safe and accurate placement of pedicle screws remains a critical step in open and minimally invasive spine surgery. The diffuse reflectance spectroscopy (DRS) technique may offer the possibility of intra-operative guidance for pedicle screw placement. Currently, Magnetic Resonance Imaging (MRI) is one of the most accurate techniques used to measure fat concentration in tissues. Therefore, the purpose of this study is to compare the accuracy of fat content measured invasively in vertebrae using DRS and validate it against the Proton density fat fraction (PDFF) derived via MRI. Chemical shift-encoding-based water-fat imaging of the spine was first performed on six cadavers. PDFF images were computed and manually segmented. 23 insertions using a custom-made screw probe with integrated optical fibers were then performed under cone beam computer tomography (CBCT). DR spectra were recorded at several positions along the trajectory as the optical screw probe was inserted turn by turn into the vertebral body. Fat fractions determined via DRS and MRI techniques were compared by spatially correlating the optical screw probe position within the vertebrae on CBCT images with respect to the PDFF images. The fat fraction determined by DRS was found to have a high correlation with those determined by MRI, with a Pearson coefficient of 0.950 (P< 0.001) as compared with PDFF measurements calculated from the MRI technique. Additionally, the two techniques were found to be comparable for fat fraction quantification within vertebral bodies (R² = 0.905).

Instrumentation complication rates following spine surgery: a report from the Scoliosis Research Society (SRS) morbidity and mortality database

Background

Objective of this study is to evaluate demographics, risk factors, and incidence of instrumentation related complications (IRC) in spinal surgeries from 2009-2012. The Scoliosis Research Society (SRS) morbidity and mortality (M&M) database has tremendous value in orthopaedic surgery. SRS gathers surgeon-reported complications, including instrumentation failure, visual complications, neurological deficits, infections, and death. Limited literature exists on the incidence of perioperative instrumentation complications in deformity surgery. We utilized the SRS database to evaluate demographics, risk factors, and incidence of IRC in spinal surgeries from 2009-2012.

Methods

The SRS M&M database was queried for IRC in patients undergoing surgery for scoliosis, spondylolisthesis, and kyphosis from 2009-2012. Demographics, comorbidities, diagnoses, curve magnitude, and intraoperative characteristics were analyzed. Intraoperative characteristics included surgical approach, performance of fusion or osteotomy, operative times, blood loss, instrumentation used, and documented instrumentation complication.

Results

A total of 167,972 patients were identified, including 311 IRC. The overall IRC rate was 0.19% (18.5 per 10,000 patients), which decreased significantly from 2009-2012 (0.37% vs. 0.19%, P<0.001). The mean age of patients with IRC was 38.5±25.5 years. Most common comorbidities included hypertension (23.5%), pulmonary disease (13.5%), diabetes (10.6%), smoking (8.7%), and vascular disease (7.1%). IRC occurred in 206 (66.2%) patients with scoliosis, 58 (18.6%) with spondylolisthesis, and 45 (14.5%) with kyphosis. Compared to patients with spondylolisthesis, patients with kyphosis (0.27% vs. 0.11%, P<0.001) and scoliosis (0.21% vs. 0.11%, P<0.001), experienced significantly more IRC. IRC included implant failure (23.3%), migration (28.3%), and malpositioned implants (48.6%). New perioperative neurologic deficits were reported in 146 (46.9%) patients, and 84 (27%) of these implants were removed.

Conclusions

IRC occur in approximately 18.5 per 10,000 deformity patients, with a rate significantly higher in patients with kyphosis. The potentially avoidable occurrence of implant malpositioning represents nearly 50% of these complications. Closer attention to posterior bony anatomy, improved intraoperative imaging with utilization of navigation or robotic guidance may decrease these complications.

Robot-Assisted Versus Fluoroscopy-Guided Pedicle Screw Placement in Transforaminal Lumbar Interbody Fusion for Lumbar Degenerative Disease

OBJECTIVE

To compare the clinical accuracy and perioperative outcomes for pedicle screw placement in transforaminal lumbar interbody fusion (TLIF) between the robot-assisted (RA) technique and fluoroscopy-guided (FG) technique.

METHODS

Seventy-seven patients scheduled to undergo RA (n = 43) and FG (n = 44) TLIF surgery were included. Patient demographics, radiographic accuracy, and perioperative outcomes were recorded and compared. The accuracy of pedicle screw placement was according to the Gertzbein and Robbins scale and facet joint violation. Perioperative outcomes mainly included operative time, radiation exposure, and revisions.

RESULTS

Of the 176 screws in the RA group, 164 screws were grade A, and 9, 2, and 1 screws were grades B, C, and D, respectively. Of the 204 screws in the FG group, 175 screws were grade A, with 16 screws scored as grade B, 8 screws scored as grade C, 3 screws scored as grade D, and 2 screws scored as grade E. The rate of perfect screw position (grade A) was higher in the RA group than in the FG group (93.2% vs. 85.8%, respectively; P = 0.020). In the FG group, 191 screws (93.6%) were clinically acceptable (groups A and B), whereas more acceptable screw positions were achieved in the RA group (98.3%; P = 0.024). Fewer screws in the RA group violated the proximal facet joint (5 vs. 24 screws, respectively; P = 0.001). The radiation dose was lower in the RA group (25.9 ± 14.2 vs. 70.5 ± 27.3 μSv, respectively; P < 0.001). Two screws in the FG group required a revision, but no revision was required in the RA group.

CONCLUSIONS

RA pedicle screw placement is an accurate and safe procedure in TLIF for lumbar degenerative disease.