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

Accuracy of Subaxial Cervical Pedicle Screw Placement Using Direct Visualization Versus Computed Tomography-Based Navigation

STUDY DESIGN

Retrospective analysis of operative data from cadaveric cervical spines.

OBJECTIVE

To evaluate the accuracy of neuronavigation compared with laminotomy with direct visualization (DV) of the pedicle for placement of subaxial pedicle screws.

SUMMARY OF BACKGROUND DATA

Subaxial pedicle screws provide superior fixation compared with other posterior cervical fixation strategies. However, high accuracy is required for safe placement, given the proximity of critical neurovascular structures. Computed tomography (CT)-based neuronavigation has increased in popularity for placement of spinal implants, including subaxial pedicle screws. However, the accuracy of the technique for this application has not been extensively evaluated.

METHODS

Six fresh-frozen cadaveric spines (occiput to T2) were prepared. Pedicle screws were placed from C3 to C7 on either side using either the DV or neuronavigation technique (alternating sides between specimens). Pedicles with diameters <4 mm were excluded. For the DV technique, a hemilaminotomy was performed for DV of pedicle borders and to determine appropriate screw medialization and trajectory. Neuronavigation screws were placed using CT-based navigation with a reference frame mounted on the C2 spinous process. Screw position was evaluated using postoperative CT, and breaches were classified using the Neo classification.

RESULTS

Fifty pedicle screws were placed at 25 levels in 6 cadaveric spines; 25 screws each were placed using neuronavigation or DV. No significant difference in accuracy was found between the 2 techniques. Three (12%) breaches occurred in the DV group, and 9 (36%) breaches occurred in the neuronavigation group (P=0.10). The breaches were evenly distributed across all levels. There were no high-grade breaches with DV and only 1 (4.0%) with neuronavigation (P>0.99). Average pedicle cortical and medullary bone widths were higher for levels with no breach (P=0.009 and P=0.02, respectively).

CONCLUSIONS

High accuracy can be achieved with both neuronavigation and DV for placement of subaxial cervical pedicle screws in cadavers.

Feasibility and Accuracy of Thoracolumbar Pedicle Screw Placement Using an Augmented Reality Head Mounted Device

Background: To investigate the accuracy of augmented reality (AR) navigation using the Magic Leap head mounted device (HMD), pedicle screws were minimally invasively placed in four spine phantoms. Methods: AR navigation provided by a combination of a conventional navigation system integrated with the Magic Leap head mounted device (AR-HMD) was used. Forty-eight screws were planned and inserted into Th11-L4 of the phantoms using the AR-HMD and navigated instruments. Postprocedural CT scans were used to grade the technical (deviation from the plan) and clinical (Gertzbein grade) accuracy of the screws. The time for each screw placement was recorded. Results: The mean deviation between navigation plan and screw position was 1.9 ± 0.7 mm (1.9 [0.3–4.1] mm) at the entry point and 1.4 ± 0.8 mm (1.2 [0.1–3.9] mm) at the screw tip. The angular deviation was 3.0 ± 1.4° (2.7 [0.4–6.2]°) and the mean time for screw placement was 130 ± 55 s (108 [58–437] s). The clinical accuracy was 94% according to the Gertzbein grading scale. Conclusion: The combination of an AR-HMD with a conventional navigation system for accurate minimally invasive screw placement is feasible and can exploit the benefits of AR in the perspective of the surgeon with the reliability of a conventional navigation system.

State of the art review of new technologies in spine deformity surgery-robotics and navigation

STUDY DESIGN/METHODS

Review article.

OBJECTIVES

The goal of this article is to review the available evidence for computerized navigation and robotics as an accuracy improvement tool for spinal deformity surgery, as well as to consider potential complications, impact on clinical outcomes, radiation exposure, and costs. Pedicle screw and rod construct are widely utilized for posterior spinal fixation in spinal deformity correction. Freehand placement of pedicle screws has long been utilized, although there is variable potential for inaccuracy depending on surgeon skill and experience. Malpositioned pedicle screws may have significant clinical implications ranging from nerve root irritation, inadequate fixation, CSF leak, perforation of the great vessels, or spinal cord damage. Computer-based navigation and robotics systems were developed to improve pedicle screw insertion accuracy and consistency, and decrease the risk of malpositioned pedicle fixation. The available evidence suggests that computer-based navigation and robotic-assisted guidance systems for pedicle cannulation are at least equivalent, and in several reports superior, to freehand techniques in terms of accuracy. CT and robotic navigation systems do appear to decrease radiation exposure to the operative team in some reports. Published reports do indicate longer operative times with use of robotic navigation compared with traditional freehand techniques for pedicle screw placement. To date, there is no conclusive evidence that use of CT or robotic navigation has any measurable impact on patient outcomes or overall complication reduction. There are theoretical advantages with robotic and CT navigation in terms of both speed and accuracy for severe spinal deformity or complex revision cases, however, there is a need for studies to investigate this technology in these specific cases. There is no evidence to date demonstrating the cost effectiveness of CT or robotic navigation as compared with traditional pedicle cannulation techniques.

CONCLUSIONS

The review of available evidence suggests that computer-based navigation and robotic-assisted guidance systems for pedicle cannulation are at least equivalent, and in several reports superior, to freehand techniques in terms of radiographic accuracy. There is no current clinical evidence that the use of navigation or robotic techniques leads to improved patient outcomes or decreased overall complications or reoperation rates, and the use of these systems may substantially increase surgical costs.

LEVEL OF EVIDENCE

V.

Evaluating robotic pedicle screw placement against conventional modalities: a systematic review and network meta-analysis

OBJECTIVE

Several approaches have been studied for internal fixation of the spine using pedicle screws (PSs), including CT navigation, 2D and 3D fluoroscopy, freehand, and robotic assistance. Robot-assisted PS placement has been controversial because training requirements, cost, and previously unclear benefits. This meta-analysis compares screw placement accuracy, operative time, intraoperative blood loss, and overall complications of PS insertion using traditional freehand, navigated, and robot-assisted methods.

METHODS

A systematic review was performed of peer-reviewed articles indexed in several databases between January 2000 and August 2021 comparing ≥ 2 PS insertion methods with ≥ 10 screws per treatment arm. Data were extracted for patient outcomes, including PS placement, misplacement, and accuracy; operative time, overall complications, intraoperative blood loss, postoperative hospital length of stay, postoperative Oswestry Disability Index (ODI) score, and postoperative visual analog scale (VAS) score for back pain. Risk of bias was assessed using the Newcastle-Ottawa score and Cochrane tool. A network meta-analysis (NMA) was performed to estimate PS placement accuracy as the primary outcome.

RESULTS

Overall, 78 studies consisting of 6262 patients and > 31,909 PSs were included. NMA results showed that robot-assisted and 3D-fluoroscopy PS insertion had the greatest accuracy compared with freehand (p < 0.01 and p < 0.001, respectively), CT navigation (p = 0.02 and p = 0.04, respectively), and 2D fluoroscopy (p < 0.01 and p < 0.01, respectively). The surface under the cumulative ranking (SUCRA) curve method further demonstrated that robot-assisted PS insertion accuracy was superior (S = 0.937). Optimal screw placement was greatest in robot-assisted (S = 0.995) placement, and misplacement was greatest with freehand (S = 0.069) approaches. Robot-assisted placement was favorable for minimizing complications (S = 0.876), while freehand placement had greater odds of complication than robot-assisted (OR 2.49, p < 0.01) and CT-navigation (OR 2.15, p = 0.03) placement.

CONCLUSIONS

The results of this NMA suggest that robot-assisted PS insertion has advantages, including improved accuracy, optimal placement, and minimized surgical complications, compared with other PS insertion methods. Limitations included overgeneralization of categories and time-dependent effects.

Learning curves in robot-assisted spine surgery: a systematic review and proposal of application to residency curricula

OBJECTIVE

Spine robots have seen increased utilization over the past half decade with the introduction of multiple new systems. Market research expects this expansion to continue over the next half decade at an annual rate of 20%. However, because of the novelty of these devices, there is limited literature on their learning curves and how they should be integrated into residency curricula. With the present review, the authors aimed to address these two points.

METHODS

A systematic review of the published English-language literature on PubMed, Ovid, Scopus, and Web of Science was conducted to identify studies describing the learning curve in spine robotics. Included articles described clinical results in patients using one of the following endpoints: operative time, screw placement time, fluoroscopy usage, and instrumentation accuracy. Systems examined included the Mazor series, the ExcelsiusGPS, and the TiRobot. Learning curves were reported in a qualitative synthesis, given as the mean improvement in the endpoint per case performed or screw placed where possible. All studies were level IV case series with a high risk of reporting bias.

RESULTS

Of 1579 unique articles, 97 underwent full-text review and 21 met the inclusion and exclusion criteria; 62 articles were excluded for not presenting primary data for one of the above-described endpoints. Of the 21 articles, 18 noted the presence of a learning curve in spine robots, which ranged from 3 to 30 cases or 15 to 62 screws. Only 12 articles performed regressions of one of the endpoints (most commonly operative time) as a function of screws placed or cases performed. Among these, increasing experience was associated with a 0.24- to 4.6-minute decrease in operative time per case performed. All but one series described the experience of attending surgeons, not residents.

CONCLUSIONS

Most studies of learning curves with spine robots have found them to be present, with the most common threshold being 20 to 30 cases performed. Unfortunately, all available evidence is level IV data, limited to case series. Given the ability of residency to allow trainees to safely perform these cases under the supervision of experienced senior surgeons, it is argued that a curriculum should be developed for senior-level residents specializing in spine comprising a minimum of 30 performed cases.

Clinical Practice in Spine Surgery: An International Survey

BACKGROUND

 The availability of diverse and sophisticated surgical options to treat spine conditions is compounded by the scarcity of high-level evidence to guide decision-making. Although studies on discrete treatments are frequently published, little information is available regarding real-world surgical practice. We intended to survey spine surgeons to assess clinical management of common spine diagnosis in day-to-day settings.

METHODS

 An online survey was distributed among neurosurgeons and orthopaedic surgeons worldwide. The obtained assessment of common surgical practice is contextualized in a review of the best available evidence.

RESULTS

 The survey was answered by more than 310 members of several European, Australasian, and South African professional societies. The submitted responses translate a surgical practice generally grounded on evidence, favoring well-tried techniques, providing comprehensive treatment for the most severe diagnoses. Such practice comes mostly from neurosurgeons focused on spine surgery, practicing in teaching hospitals.

CONCLUSION

 We believe that the pragmatic, day-to-day approach to spine conditions captured in the present survey offers an informative insight to involved surgeons.

Initial Intraoperative Experience with Robotic-Assisted Pedicle Screw Placement with Cirq® Robotic Alignment: An Evaluation of the First 70 Screws

BACKGROUND

Robot-guided spine surgery is based on a preoperatively planned trajectory that is reproduced in the operating room by the robotic device. This study presents our initial experience with thoracolumbar pedicle screw placement using Brainlab's Cirq^® surgeon-controlled robotic arm (BrainLab, Munich, Germany).

METHODS

All patients who underwent robotic-assisted implantation of pedicle screws in the thoracolumbar spine were included in the study. Our workflow, consisting of preoperative imagining, screw planning, intraoperative imaging with automatic registration, fusion of the preoperative and intraoperative imaging with a review of the preplanned screw trajectories, robotic-assisted insertion of K-wires, followed by a fluoroscopy-assisted insertion of pedicle screws and control iCT scan, is described.

RESULTS

A total of 12 patients (5 male and 7 females, mean age 67.4 years) underwent 13 surgeries using the Cirq^® Robotic Alignment Module for thoracolumbar pedicle screw implantation. Spondylodiscitis, metastases, osteoporotic fracture, and spinal canal stenosis were detected. A total of 70 screws were implanted. The mean time per screw was 08:27 ± 06:54 min. The mean time per screw for the first 7 surgeries (first 36 screws) was 16:03 ± 09:32 min and for the latter 6 surgeries (34 screws) the mean time per screw was 04:35 ± 02:11 min (p < 0.05). Mean entry point deviation was 1.9 ± 1.23 mm, mean deviation from the tip of the screw was 2.61 ± 1.6 mm and mean angular deviation was 3.5° ± 2°. For screw-placement accuracy we used the CT-based Gertzbein and Robbins System (GRS). Of the total screws, 65 screws were GRS A screws (92.85%), one screw was a GRS B screw, and two further screws were grade C. Two screws were D screws (2.85%) and underwent intraoperative revision. There were no perioperative deficits.

CONCLUSION

Brainlab's Cirq^® Robotic Alignment surgeon-controlled robotic arm is a safe and beneficial method for accurate thoracolumbar pedicle screw placement with high accuracy.

Robotic navigation in spine surgery: Where are we now and where are we going?

Robotic navigation is a new and rapidly emerging niche within minimally invasive spine surgery. The robotic arms-race began in 2004 and has resulted in no less than four major robotic surgical adjuncts. Current Food and Drug Administration (FDA)-approved applications of robotic navigation are limited to pedicle screw instrumentation, but new indications and experimental applications are rapidly emerging. As with any new technology, robotic navigation must be vetted for clinical efficacy, efficiency, safety, and cost-effectiveness. Given the rapid advancements made on a yearly basis, it is important to make frequent and objective assessments of the available technology. Thus, the authors seek to provide the most up-to-date review of the history, currently available technology, learning curve, novel applications, and cost effectiveness of today's available robotic systems as it relates to spine surgery.

The study of distance changes between lumbar bi-cortical pedicle screws and anterior large vessels in patients with lumbar spondylolisthesis

OBJECTIVE

This paper was a anatomical radiographic study of distance between lumbar bi-cortical pedicle screws (BPSs) and anterior large vessels (ALVs) in patients with lumbar spondylolisthesis, and to provide clinical basis for evaluating the safety of bi-cortical pedicle screw implantation during lumbar spondylolisthesis.

METHODS

Complete Computed tomography (CT) data of 104 patients with grade I lumbar spondylolisthesis (L4 52 and L5 52) and 107 non-spondylolisthesis patients (control group) were collected in this study. The distances between lumbar 4,5(L4,5) and sacrum 1(S1) BPSs and ALVs (abdominal aorta, inferior vena cava, left and right common iliac artery, internal and external iliac artery) were respectively measured at different transverse screw angles (TSAs) (L4:5°,10°; L5:10°,15°; S1:0°,5°,10°) and analyzed by SPSS (v25.0). There were three types of distances from the anterior vertebral cortex (AVC) to the ALVs (D_AVC-ALV): D_AVC-ALV N, D_AVC-ALV ≥ 0.50 cm, and D_AVC-ALV < 0.50 cm; these different distances represented non-contact, distant and close ALV respectively.

RESULTS

We calculated the incidences of screw tip contacting large vessels at different TSAs and provided the appropriate angle of screw implantation. In non-spondylolisthesis group, in L4, the appropriate left TSA was 5°, and the incidence of the close ALV was 4.62%. In S1, the appropriate left TSA was 0° and the incidence of the close ALV was 22.4%, while the appropriate right TSA was 10° and the incidence of the close ALV was 17.8%. In L4 spondylolisthesis group, in L4, the appropriate left TSA was 5°, and the incidence of the close ALV was 3.8%. In L5 spondylolisthesis group, in S1, the appropriate left TSA was 0° and the incidence of the close ALV was 19.2%, while the appropriate right TSA was 10° and the incidence of the close ALV was 21.2%. The use of BPS was not appropriate on the right side of L4 or on the either side of L5 both in spondylolisthesis and control group. In patients with lumbar 4 spondylolisthesis, the incidences of screw tip contacting large vessels were less than the control group in both L4 and 5. In patients with lumbar 5 spondylolisthesis, the incidences of screw tip contacting large vessels were less than the control group in L5, while there were no significant difference in S1.

CONCLUSION

It is very important that considering the anatomical relationship between the AVC and the ALVs while planning BPSs. The use of BPS does not apply to every lumbar vertebra. In patients with lumbar spondylolisthesis and non-spondylolisthesis patients, the incidences of screw tip contacting large vessels are different.

Robotics and Spine Surgery: Lessons From the Personal Computer and Industrial Revolutions

Over the past decade, several review articles have evaluated the techniques and outcomes of robotics vs traditional methods in spine surgery. Recently, robot-assisted pedicle screw placement has emerged, representing an important milestone in the evolution of spine surgery. In the present article, the authors aim to provide the historical context regarding the use and growth of spinal robotics through the lens of the Industrial Revolution and the personal computer revolution. While the former provides insight into the current implications of robotics in spine surgery, the latter predicts future steps in this arena.

Intraoperative computed tomography-guided navigation versus fluoroscopy for single-position surgery after lateral lumbar interbody fusion

There are no reports comparing fluoroscopy and intraoperative computed tomography (CT) navigation in lateral single-position surgery (SPS) in terms of surgical outcomes or implant-related complications. Therefore, the purpose of this study was to use radiological evaluation to compare the incidence of instrument-related complications in SPS of lateral lumbar interbody fusion (LLIF) using fluoroscopy with that using CT navigation techniques. We evaluated 99 patients who underwent lateral SPS. Twenty-six patients had a percutaneous pedicle screw (PPS) inserted under fluoroscopy (SPS-C group), and 73 patients had a PPS inserted under intraoperative CT navigation (SPS-O group). Average operation time was shorter in the SPS-C group than in the SPS-O group (88.4 ± 24.4 min versus 111.9 ± 35.3 min, respectively, P = 0.003). However, there was no significant difference between the two groups in postoperative thigh symptoms or reoperation rate. The screw insertion angle of the SPS-C group was smaller than that of the SPS-O group, but there was no significant difference in the rate of screw misplacement (4.6% versus 3.4%, respectively, P = 0.556). By contrast, facet joint violation (FJV) was significantly lower in the SPS-O group than in the SPS-C group (8.4% versus 21.3%, respectively, P < 0.001). While fluoroscopy was superior to intraoperative CT navigation in terms of mean surgery time, there was no significant difference in the accuracy of PPS insertion between fluoroscopy and intraoperative CT navigation. The advantage of intraoperative CT navigation over fluoroscopy is that it significantly decreases the occurrence of FJV in SPS.

Utility of Power Tool and Intraoperative Neuromonitoring for Percutaneous Pedicle Screw Placement in Single Position Surgery: A Technical Note

OBJECTIVE

This study aimed to demonstrate the utility of power tools and intraoperative neuromonitoring of percutaneous pedicle screw (PPS) insertion (so-called PPS monitoring) by SINGLE-position surgery (SPS) after lateral lumbar interbody fusion.

METHODS

A retrospective analysis of medical records from a single center was performed to identify patients who underwent SPS for lateral lumbar interbody fusion and posterior fixation using PPS during intraoperative computed tomography navigation from 2020 to 2021. We investigated the PPS insertion time and screw positional accuracy of patients who underwent SPS involving power tools and PPS monitoring during this period. In this technical note, we report on this surgical technique.

RESULTS

Twenty-four patients (mean age 72.0 ± 8.5 years, range 53-81 years) were included in this study. There were no intraoperative complications in all cases. Posterior fixation using PPS was added in all cases, and a total of 106 PPSs were inserted. It took an average of 6.2 ± 2.4 seconds to insert the PPS from the PPS insertion point to the end using a power tool and PPS monitoring. Moreover, there were no cases of pedicle breaches.

CONCLUSIONS

Similar to previous reports related to power tools in the prone position, the lateral decubitus SPS technique can also use power tools to save PPS insertion time. Furthermore, we suggest that the use of PPS monitoring may prevent erroneous PPS insertions by using intraoperative computed tomography navigation in advance.

Clinical accuracy and initial experience with augmented reality-assisted pedicle screw placement: the first 205 screws

OBJECTIVE

Augmented reality (AR) is a novel technology which, when applied to spine surgery, offers the potential for efficient, safe, and accurate placement of spinal instrumentation. The authors report the accuracy of the first 205 pedicle screws consecutively placed at their institution by using AR assistance with a unique head-mounted display (HMD) navigation system.

METHODS

A retrospective review was performed of the first 28 consecutive patients who underwent AR-assisted pedicle screw placement in the thoracic, lumbar, and/or sacral spine at the authors' institution. Clinical accuracy for each pedicle screw was graded using the Gertzbein-Robbins scale by an independent neuroradiologist working in a blinded fashion.

RESULTS

Twenty-eight consecutive patients underwent thoracic, lumbar, or sacral pedicle screw placement with AR assistance. The median age at the time of surgery was 62.5 (IQR 13.8) years and the median body mass index was 31 (IQR 8.6) kg/m2. Indications for surgery included degenerative disease (n = 12, 43%); deformity correction (n = 12, 43%); tumor (n = 3, 11%); and trauma (n = 1, 4%). The majority of patients (n = 26, 93%) presented with low-back pain, 19 (68%) patients presented with radicular leg pain, and 10 (36%) patients had documented lower extremity weakness. A total of 205 screws were consecutively placed, with 112 (55%) placed in the lumbar spine, 67 (33%) in the thoracic spine, and 26 (13%) at S1. Screw placement accuracy was 98.5% for thoracic screws, 97.8% for lumbar/S1 screws, and 98.0% overall.

CONCLUSIONS

AR depicted through a unique HMD is a novel and clinically accurate technology for the navigated insertion of pedicle screws. The authors describe the first 205 AR-assisted thoracic, lumbar, and sacral pedicle screws consecutively placed at their institution with an accuracy of 98.0% as determined by a Gertzbein-Robbins grade of A or B.

Emerging Technologies in the Treatment of Adult Spinal Deformity

Outcomes for adult spinal deformity continue to improve as new technologies become integrated into clinical practice. Machine learning, robot-guided spinal surgery, and patient-specific rods are tools that are being used to improve preoperative planning and patient satisfaction. Machine learning can be used to predict complications, readmissions, and generate postoperative radiographs which can be shown to patients to guide discussions about surgery. Robot-guided spinal surgery is a rapidly growing field showing signs of greater accuracy in screw placement during surgery. Patient-specific rods offer improved outcomes through higher correction rates and decreased rates of rod breakage while decreasing operative time. The objective of this review is to evaluate trends in the literature about machine learning, robot-guided spinal surgery, and patient-specific rods in the treatment of adult spinal deformity.

The Clinical Impact of Image Guidance and Robotics in Spinal Surgery: A Review of Safety, Accuracy, Efficiency, and Complication Reduction

Image guidance (IG) and robotic-assisted (RA) surgery are modern technological advancements that have provided novel ways to perform precise and accurate spinal surgery. These innovations supply real-time, three-dimensional imaging information to aid in instrumentation, decompression, and implant placement. Although nothing can replace the knowledge and expertise of an experienced spine surgeon, these platforms do have the potential to supplement the individual surgeon's capabilities. Specific advantages include more precise pedicle screw placement, minimally invasive surgery with less reliance on intraoperative fluoroscopy, and lower radiation exposure to the surgeon and staff. As these technologies have become more widely adopted over the years, novel uses such as tumor resection have been explored. Disadvantages include the cost of implementing IG and robotics platforms, the initial learning curve for both the surgeon and the staff, and increased patient radiation exposure in scoliosis surgery. Also, given the relatively recent transition of many procedures from inpatient settings to ambulatory surgery centers, access to current devices may be cost prohibitive and not as readily available at some centers. Regarding patient-related outcomes, much further research is warranted. The short-term benefits of minimally invasive surgery often bolster the perioperative and early postoperative outcomes in many retrospective studies on IG and RA surgery. Randomized controlled trials limiting such confounding factors are warranted to definitively show potential independent improvements in patient-related outcomes specifically attributable to IG and RA alone. Nonetheless, irrespective of these current unknowns, it is clear that these technologies have changed the field and the practice of spine surgery. Surgeons should be familiar with the potential benefits and tradeoffs of these platforms when considering adopting IG and robotics in their practices.

Cirq robotic arm-assisted transpedicular instrumentation with intraoperative navigation: technical note and case series with 714 thoracolumbar screws

The Cirq is a surgeon-controlled robotic arm that provides a new technique for accurately placing transpedicular screws. This report aims to present a technical report and our experience with this new robotic arm combined with intraoperative navigation. Technique and workflow using the Cirq robotic arm with intraoperative navigation is described. A retrospective review was conducted of all patients undergoing elective open thoracic/lumbar fusion surgery by a single surgeon in the first year of using the novel Cirq robotic arm. Descriptive analysis of patient and operative variables was performed. A total of 84 patients underwent placement of a total 714 transpedicular screws using the Cirq robotic arm. Most (69.1%) underwent 3-6 level fusion procedures. Mean operative time was 198 min total and 28 min when adjusted per screw. There was a learning curve with operative time per screw decreasing from 32 to 25 min from the first to second half of cases (p = 0.057). There were no intraoperative screw revisions and 2.4% (2/84) required instrumentation revision and return to the operating room. The Cirq robotic arm is seamlessly incorporated into the workflow of a transpedicular fusion. Our experience with over 700 pedicle screw placements using the Cirq robot demonstrates efficacy and safety although further comparative studies are needed.

Comparing the Efficacy of Radiation Free Machine-Vision Image-Guided Surgery With Traditional 2-Dimensional Fluoroscopy: A Randomized, Single-Center Study

Background: Three-dimensional (3D) computer-assisted navigation (CAN) has emerged as a potential alternative to 2-dimensional (2D) fluoroscopy in the surgical placement of spinal instrumentation. Recently, 3D-CAN systems have improved significantly in their ability to provide real-time anatomical referencing while shortening the registration and set-up time. A novel system in navigation, Machine-Vision Image-Guided Surgery (MvIGS; 7D Surgical, Toronto, Canada) was cleared by the US Food and Drug Administration, but its potential benefits in reducing intra-operative radiation exposure to patients and enhancing surgical accuracy of pedicle screw placement are not fully known. Purpose: We sought to conduct a prospective, randomized, clinical study comparing the 3D-MvIGS spinal navigation system and 2D-fluoroscopy for pedicle screw insertion up to 3 levels (T10-S1) and for various measures of surgical efficacy. Methods: Sixty-two eligible patients were randomized to receive spine surgery using either the 3D-MvIGS group or the conventional 2D-fluoroscopy for pedicle screw fixation for the treatment of spinal stenosis and degenerative spondylolisthesis. Intra-operative parameters and procedure-related unintended protocol violations were recorded. Results: Operative time and estimated blood loss were not significantly different between groups. Radiation time and exposure to patients were significantly reduced in the 3D-MvIGS group. There was no difference between groups in pedicle screw placement accuracy (2D-fluoroscopy group, 96.6%; 3D-MvIGS group, 94.2%). There were no major complications or cases that required revision surgery. Conclusion: The 3D-MvIGS navigation system performed comparably with 2D-fluoroscopy in terms of pedicle screw placement accuracy and operative time. The 3D-MvIGS showed a significant reduction in radiation exposure to patients. In more complex cases or larger cohorts, the true value of greater anatomical visualization can be elucidated.

Accuracy of Pedicle Screw Placement Using Intraoperative CT-Guided Navigation and Conventional Fluoroscopy for Lumbar Spondylosis

Background

Transpedicular screws are a common adjunct for lumbar spine fusion. Accurate screw placement to prevent neurological injury has been the subject of many studies. The adoption of spine neuronavigation has shown a significant decrease in screw malposition morbidity. We aim to evaluate the accuracy of pedicle screw insertion using intraoperative CT-guided navigation in lumbar spondylosis.

Methods

We reviewed a prospective registry-based cohort study. This included patients who underwent transpedicular screws insertion for lumbar spondylosis under intraoperative CT-guided navigation (iCT-Nav) and compared it to another group operated using conventional fluoroscopy (FS) over one year. In addition, the correlation between clinical outcome using the visual analog scale (VAS) and short 12 physical component scores (SF-12 PCS) and hospital stay was reported.

Results

Fifteen patients were included in the iCT-Nav group compared to 42 patients in the FS group. The median age of the iCT-Nav group was 59.3 years old (27-76 years) versus 45 years old (20-60 years) in the FS group. The number of screws was 98 in the iCT-Nav group and 252 screws in the FS group. Based on more than 2-mm breach increments measured on CT images, lumbar pedicular screw placement accuracy was 100% in the iCT-Nav group and 86.9% in the FS group. None of the patients in the iCT-Nav group had to undergo any postoperative revisions. On the other hand, two patients of the FS group developed new postoperative symptoms related to displaced screws and required readmission and revision surgery.

Conclusion

In a commonly performed pedicular fixation in lumbar spondylosis, iCT-Nav has been shown to improve the accuracy of pedicle screw placement, hospital stay, and functional outcomes compared to FS. 

SpineDepth: A Multi-Modal Data Collection Approach for Automatic Labelling and Intraoperative Spinal Shape Reconstruction Based on RGB-D Data

Computer aided orthopedic surgery suffers from low clinical adoption, despite increased accuracy and patient safety. This can partly be attributed to cumbersome and often radiation intensive registration methods. Emerging RGB-D sensors combined with artificial intelligence data-driven methods have the potential to streamline these procedures. However, developing such methods requires vast amount of data. To this end, a multi-modal approach that enables acquisition of large clinical data, tailored to pedicle screw placement, using RGB-D sensors and a co-calibrated high-end optical tracking system was developed. The resulting dataset comprises RGB-D recordings of pedicle screw placement along with individually tracked ground truth poses and shapes of spine levels L1-L5 from ten cadaveric specimens. Besides a detailed description of our setup, quantitative and qualitative outcome measures are provided. We found a mean target registration error of 1.5 mm. The median deviation between measured and ground truth bone surface was 2.4 mm. In addition, a surgeon rated the overall alignment based on 10% random samples as 5.8 on a scale from 1 to 6. Generation of labeled RGB-D data for orthopedic interventions with satisfactory accuracy is feasible, and its publication shall promote future development of data-driven artificial intelligence methods for fast and reliable intraoperative registration.

Real-time navigation guidance with intraoperative CT imaging for pedicle screw placement using an augmented reality head-mounted display: a proof-of-concept study

OBJECTIVE

Augmented reality (AR) has the potential to improve the accuracy and efficiency of instrumentation placement in spinal fusion surgery, increasing patient safety and outcomes, optimizing ergonomics in the surgical suite, and ultimately lowering procedural costs. The authors sought to describe the use of a commercial prototype Spine AR platform (SpineAR) that provides a commercial AR head-mounted display (ARHMD) user interface for navigation-guided spine surgery incorporating real-time navigation images from intraoperative imaging with a 3D-reconstructed model in the surgeon's field of view, and to assess screw placement accuracy via this method.

METHODS

Pedicle screw placement accuracy was assessed and compared with literature-reported data of the freehand (FH) technique. Accuracy with SpineAR was also compared between participants of varying spine surgical experience. Eleven operators without prior experience with AR-assisted pedicle screw placement took part in the study: 5 attending neurosurgeons and 6 trainees (1 neurosurgical fellow, 1 senior orthopedic resident, 3 neurosurgical residents, and 1 medical student). Commercially available 3D-printed lumbar spine models were utilized as surrogates of human anatomy. Among the operators, a total of 192 screws were instrumented bilaterally from L2-5 using SpineAR in 24 lumbar spine models. All but one trainee also inserted 8 screws using the FH method. In addition to accuracy scoring using the Gertzbein-Robbins grading scale, axial trajectory was assessed, and user feedback on experience with SpineAR was collected.

RESULTS

Based on the Gertzbein-Robbins grading scale, the overall screw placement accuracy using SpineAR among all users was 98.4% (192 screws). Accuracy for attendings and trainees was 99.1% (112 screws) and 97.5% (80 screws), respectively. Accuracy rates were higher compared with literature-reported lumbar screw placement accuracy using FH for attendings (99.1% vs 94.32%; p = 0.0212) and all users (98.4% vs 94.32%; p = 0.0099). The percentage of total inserted screws with a minimum of 5° medial angulation was 100%. No differences were observed between attendings and trainees or between the two methods. User feedback on SpineAR was generally positive.

CONCLUSIONS

Screw placement was feasible and accurate using SpineAR, an ARHMD platform with real-time navigation guidance that provided a favorable surgeon-user experience.

First in-human report of the clinical accuracy of thoracolumbar percutaneous pedicle screw placement using augmented reality guidance

OBJECTIVE

Augmented reality (AR) is an emerging technology that has great potential for guiding the safe and accurate placement of spinal hardware, including percutaneous pedicle screws. The goal of this study was to assess the accuracy of 63 percutaneous pedicle screws placed at a single institution using an AR head-mounted display (ARHMD) system.

METHODS

Retrospective analyses were performed for 9 patients who underwent thoracic and/or lumbar percutaneous pedicle screw placement guided by ARHMD technology. Clinical accuracy was assessed via the Gertzbein-Robbins scale by the authors and by an independent musculoskeletal radiologist. Thoracic pedicle subanalysis was also performed to assess screw accuracy based on pedicle morphology.

RESULTS

Nine patients received thoracic or lumbar AR-guided percutaneous pedicle screws. The mean age at the time of surgery was 71.9 ± 11.5 years and the mean number of screws per patient was 7. Indications for surgery were spinal tumors (n = 4, 44.4%), degenerative disease (n = 3, 33.3%), spinal deformity (n = 1, 11.1%), and a combination of deformity and infection (n = 1, 11.1%). Presenting symptoms were most commonly low-back pain (n = 7, 77.8%) and lower-extremity weakness (n = 5, 55.6%), followed by radicular lower-extremity pain, loss of lower-extremity sensation, or incontinence/urinary retention (n = 3 each, 33.3%). In all, 63 screws were placed (32 thoracic, 31 lumbar). The accuracy for these screws was 100% overall; all screws were Gertzbein-Robbins grade A or B (96.8% grade A, 3.2% grade B). This accuracy was achieved in the thoracic spine regardless of pedicle cancellous bone morphology.

CONCLUSIONS

AR-guided surgery demonstrated a 100% accuracy rate for the insertion of 63 percutaneous pedicle screws in 9 patients (100% rate of Gertzbein-Robbins grade A or B screw placement). Using an ARHMS system for the placement of percutaneous pedicle screws showed promise, but further validation using a larger cohort of patients across multiple surgeons and institutions will help to determine the true accuracy enabled by this technology.

Utilization trends and outcomes of computer-assisted navigation in spine fusion in the United States

BACKGROUND CONTEXT

Computer-assisted navigation (CAN) has emerged in spine surgery as an approach to improve patient outcomes. While there is substantial evidence demonstrating improved pedicle screw accuracy in CAN as compared to conventional spinal fusion (CONV), there is limited data regarding clinical outcomes and utilization trends in the United States.

PURPOSE

The purpose of this study was to determine the utilization rates of CAN in the United States, identify patient and hospital trends associated with both techniques, and to compare their results.

STUDY DESIGN

Retrospective review of national database.

PATIENT SAMPLE

Nationwide Inpatient Sample (NIS), United States national database.

OUTCOME MEASURES

CAN utilization, mortality, medical complications, neurologic complications, discharge destination, length of hospital stay, cost of hospital stay.

METHODS

The NIS database was queried to identify patients undergoing spinal fusion with CAN or CONV. CAN and CONV utilization were tracked by year and anatomic location (cervical, thoracic, lumbar/lumbosacral). Patient demographics, hospital characteristics, index length of stay (LOS), and cost of stay (COS) were compared between the cohorts. After multivariate adjustment, index hospitalization clinical outcomes were compared.

RESULTS

A total of 4,275,413 patients underwent spinal fusion surgery during the study period (2004 to 2014). CONV was performed in 98.4% (4,208,068) of cases and CAN was performed in 1.6% (67,345) of cases. The utilization rate of CAN increased from 0.04% in 2004 to 3.3% in 2014. Overall, CAN was performed most commonly in the lumbar/lumbosacral region (70.4%) compared to the cervical (20.4%) or thoracic (9.2%) regions. When normalized to region-specific rates of fusion with any technique, the proportional utilization of CAN was highest in the thoracic spine (2.7%), followed by the lumbar/lumbosacral (2.2%) and cervical (0.9%) regions. CAN utilization was positively correlated with patient factors including increasing age and number of medical comorbidities. Multivariate adjusted clinical outcomes demonstrated that compared to CONV, CAN was associated with a statistically significant decreased risk of mortality (0.28% vs 0.31%, OR=0.67, 95% CI: 0.46-0.97, p=.035) and increased risk of blood transfusions (9.1% vs 6.7%, OR=1.19, 95% CI: 1.02-1.39, p=.032). However, there was no difference in risk of neurologic complications. CAN patients had an increased average LOS (4.44 days vs. 3.97 days, p<.0001) and average COS ($34,669.49 vs $26,784.62, p<.0001) compared to CONV patients.

CONCLUSIONS

CAN utilization increased in the United States from 2004-2014. Use of CAN was proportionately higher in the thoracic and lumbar/lumbosacral regions and in older patients with more comorbidities. Given the continued trend towards increased CAN utilization, large-scale studies are needed to determine the impact of this technology on long-term clinical outcomes.

Robotic navigation system utilization for percutaneous sacroiliac screw placement: surgical setup and technique

Sacroiliac joint (SIJ) pathology is a common cause of significant pain and disability, and operative treatment consisting of SIJ fusion can be performed in cases where non-operative measures fail to provide sustained relief. Through the years, SIJ fusion has evolved from an open invasive procedure, to more recently, being performed through minimally invasive techniques. Intraoperative navigation systems and robotic guidance are becoming popularized for SIJ fusion, as well as other routine and complex spinal cases. The utility of navigation and robotics is the enhanced ability of the surgeon to place instrumentation more accurately, with less dissection, blood less, and overall operative time. We present a technique guide for robotic instrumented SIJ fusion with intraoperative navigation that we have put into practice at our institution and found to be very beneficial to patients for the above reasons. We describe the setup and utilization of these technologies intraoperatively, and provide specific case examples to highlight our technique. The described methods have been found to be effective and reproducible, allowing for minimally invasive SIJ screw placement with high accuracy and safety. We emphasize that utilizing intraoperative navigation and robotics is not meant to substitute for surgeon knowledge of case steps or anatomy, but rather to enhance safety and efficacy. To our knowledge, robotic SIJ fusion has not been previously described in the literature.

Evaluation of K-wireless robotic and navigation assisted pedicle screw placement in adult degenerative spinal surgery: learning curve and technical notes

Background

K-wireless robotic pedicle screw instrumentation with navigation is a new technology with large potential. Barriers to adoption are added registration time with robotic-navigated system and reliable screw positioning. Understanding the learning curve and limitations is crucial for successful implementation. The purpose of this study was to describe a learning curve of k-wireless robotic assisted pedicle screw placement with navigation and compare to conventional techniques.

Methods

A retrospective review of prospectively collected data of 65 consecutive adult patients underwent robotic-navigated posterior spinal fusion by a single spine surgeon. Registration, screw placement, and positioning times were recorded. All patients underwent intra-operative 3D fluoroscopy and screw trajectory was compared to pre-operative CT.

Results

A total of 364 instrumented pedicles were planned robotically, 311 (85.4%) were placed robotically; 17 screws (4.7%) converted to k-wire, 21 (5.8%) converted to freehand, and 15 (4.1%) planned freehand. Of the 311 robotically placed pedicle screws, three dimensional fluoroscopic imaging showed 291 (93.5%) to be GRS Grade A in the axial plane (fully contained within the pedicle) and 281 (90.4%) were GRS Grade A in the sagittal plane. All breached screw deviations from plan were identified on 3D fluoroscopy during surgery and repositioned and confirmed by additional 3d fluoroscopy scan. Reasons for conversion included morphology of starting point (n=18), soft tissue pressure (n=9), hypoplastic pedicles (n=6), obstructive reference pin placement (n=2), and robotic arm issues (n=1). Seventeen (5.5%) critical breaches (≥2-4 mm) were recorded in 11 patients, 9 (2.9%) critical breaches were due to soft tissue pressure causing skive. Two patients experienced 6 (1.9%) critical breaches from hypoplastic pedicles, and 3 (0.9%) unplanned lateral breaches were found in another patient. One patient (0.3%) experienced skive due to morphology and spinal instability from isthmic spondylolisthesis. Imaging showed 143 screws placed medially to plan (1.2±0.9 mm), 170 lateral (1.2±1.1 mm), 193 screws caudal (1.0±0.6 mm) and 117 cranial (0.6±0.5 mm). No adverse clinical sequelae occurred from implantation of any screw.

Conclusions

The learning curve showed improvement in screw times for the first several cases. Understanding the learning curve and situations where the robotic technique may be suboptimal can help guide the surgeon safe and effectively for adoption, as well as further refine these technologies.

Robotic-Navigated Percutaneous Pedicle Screw Placement Has Less Facet Joint Violation Than Fluoroscopy-Guided Percutaneous Screws

OBJECTIVE

To directly compare robotic-versus fluoroscopy-guided percutaneous pedicle screw (PPS) placement in thoracolumbar spine trauma with a focus on clinically acceptable pedicle screw accuracy and facet joint violation (FJV).

METHODS

A retrospective chart review assessed 37 trauma patients undergoing percutaneous thoracic and/or lumbar fixation. Postoperative computed tomography images were reviewed by authors blinded to surgical technique who assessed pedicle screw trajectory accuracy and FJV frequency.

RESULTS

Seventeen patients underwent placement of 143 PPS with robotic assistance (robot group), compared with 20 patients receiving 149 PPS using fluoroscopy assistance (control group). Overall, the robot cohort demonstrated decreased FJV frequency of 2.8% versus 14.8% in controls (P = 0.0003). When further stratified by level of surgery (i.e., upper thoracic, lower thoracic, lumbar spine), the robot group had FJV frequencies of 0%, 3.2%, and 3.7%, respectively, compared with 17.7% (P = 0.0209), 14.3% (P = 0.0455), and 11.9% (P = 0.2340) in controls. The robot group had 84.6% clinically acceptable screw trajectories compared with 81.9% in controls (P = 0.6388). Within the upper thoracic, lower thoracic, and lumbar regions, the robot group had acceptable screw trajectories of 66.7%, 87.1%, and 90.7%, respectively, compared with 58.8% (P = 0.6261), 91.1% (P = 0.5655), and 97.6% (P = 0.2263) in controls.

CONCLUSIONS

There was no significant difference in clinically acceptable screw trajectory accuracy between robotic versus fluoroscopy-guided PPS placement. However, the robot cohort demonstrated a statistically significantly decreased FJV overall and specifically within the thoracic spine region. Use of robotic technology may improve radiographic outcomes for a subset of patients or spine surgeries.

How accurate is fluoroscopy-guided percutaneous pedicle screw placement in minimally invasive TLIF?

INTRODUCTION

The accuracy of pedicle screws placement has been the subject of many studies and varied rates of screw malposition have been reported. This study evaluates the placement of pedicle screw inserted percutaneously, guided by intraoperative 2D fluoroscopy, in minimally invasive transforaminal lumbar interbody fusion (MIS-TLIF).

METHODS

Retrospective study of patients who underwent MIS-TLIF from 2007 to 2016 in a single center, for degenerative pathology. All patients had a follow-up lumbar CT scan one year after surgery to evaluate pedicle violation, location and degree. Gertzbein classification was used for description of the degree of violation.

RESULTS

This study included 241 patients, with a mean age of 57 years (SD 11.69). A total of 1045 screws were evaluated. Most patients were fused at L4-L5 or L5-S1 levels. The total rate of pedicle walls' violation was 13.97%, however only 4.31% of the screws presented violations exceeding 2 mm. Only 5 patients were reoperated because of complaints related to screw malposition (0.48% of all screws). There was a trend for an increased rate of pedicle violation for upper lumbar pedicles (p < 0.001). For S1 screws, violations were more common on left pedicle screws (17.89% vs 7.53%, p = 0.03), with an Odds Ratio of 2.68 (95% CI: 1.07-6.80).

CONCLUSION

Percutaneous pedicle screw insertion guided by intraoperative 2 D fluoroscopy in MIS-TLIF is safe and most of pedicle violations seem to be minor and without clinical consequences. In S1 screws, the surgeon's side was more prone to violation.

Evaluation of free-hand screw placement in cervical, thoracic, and lumbar spine by neurosurgical residents

BACKGROUND

Knowledge of free-hand screw technique remains critical to adequately train neurosurgical residents. The purpose of this study was to evaluate the accuracy of screw placement via the free-hand technique in lumbar, thoracic, and cervical spine by neurosurgical residents completing an enfolded spine fellowship.

METHODS

Medical records of all patients who underwent free-hand screw placement at all spinal levels over a 6-month period by senior neurosurgical residents enrolled in an in-folded spine fellowship were retrospectively reviewed. Postoperative CT images were assessed for presence and direction of cortical breach.

RESULTS

Twenty-six patients underwent 162 free-hand screw placements. The most commonly placed screws were cervical lateral mass screws (n = 69), thoracic (n = 41), and lumbar pedicle screws (n = 41). The most common indication for surgery was deformity (n = 22), followed by infection (n = 2) and trauma (n = 2). Fifty-five breaches were identified in 44 (27 %) screws placed in 21 patients (81 %). Anterior breach was identified in 22 cases (40.0 %), lateral in 12 (23.6 %), superior in 7 (12.7 %), and inferior in 7 (12.7 %), and medial in 6 (10.9 %). The most common level of breach was observed in cervical lateral mass screws (n = 19, 43 %) and least common in C2 pars screws (n = 1, 2%). With an average length of follow up of 12.1 ± 7.7 months of follow-up, no clinical sequalae of screw breach was observed.

CONCLUSIONS

Despite the high prevalence of screw breach using the free-hand technique by neurosurgical residents, the absence of clinical sequelae implies safety and emphasizes the importance of early exposure to this technique during neurosurgical residency training.

Accuracy of Pedicle Screw Placement and Four Other Clinical Outcomes of Robotic Guidance Technique versus Computer-Assisted Navigation in Thoracolumbar Surgery: A Meta-Analysis

BACKGROUND

Robotic guidance (RG) pedicle screw placement has been increasingly used to improve the rate of insertion accuracy. However, the superiority of the RG technique over computer-assisted navigation (CAN) remains debatable.

OBJECTIVE

To determine whether the Mazor RG technique is superior to CAN in terms of the rate of insertion accuracy and 4 other clinical indices, namely, intraoperative time, blood loss, complications and revision surgery caused by malposition.

METHODS

A search of PubMed, Embase, Cochrane, Web of Science, CNKI, and WanFang was conducted. We mainly aimed to evaluate the accuracy of pedicle screw placement between the Mazor RG and CAN techniques. The secondary objectives were intraoperative time, blood loss, complications, and revision surgery caused by malposition. The meta-analysis was conducted using the RevMan 5.3 and Stata 15.1 software.

RESULTS

A randomized controlled trial and 5 comparative cohort studies consisting of 529 patients and 4081 pedicle screws were included in this meta-analysis. The RG technique has a significantly higher accuracy than CAN in terms of optimal (odds ratio [OR], 2.26; 95% confidence interval [CI], 1.85-2.76; P < 0.01) and clinically acceptable (OR, 1.69; 95% CI, 1.22-2.34; P = 0.002) pedicle screw insertions. Furthermore, the RG technique showed significantly less blood loss (mean difference, -42.49; 95% CI, -78.38 to -6.61; P = 0.02) than did the CAN technique but has equivalent intraoperative time (mean difference, 0.75; 95% CI, -5.89 to 7.40; P = 0.82), complications (OR, 0.65; 95% CI, 0.32-1.33, P = 0.24), and revision surgery caused by malposition (OR, 0.46; 95% CI, 0.15-1.43, P = 0.18).

CONCLUSIONS

The Mazor RG technique is superior to CAN concerning the accuracy of pedicle screw placement. Thus, the Mazor RG technique is accurate and safe in clinical application.

Breach Rate Analysis of Pedicle Screw Instrumentation using Free-Hand Technique in the Surgical Correction of Adolescent Idiopathic Scoliosis

Introduction

Free-hand technique is one of the techniques used by spine surgeon during pedicle screw instrumentation of surgical correction of spinal deformities, including scoliosis. The previous studies showed that this technique is safe. However, some inherent factors may influence its outcomes, including screw breaching which is potentially violates spinal cord and other intimate structures. To confirm the safety and accuracy of this technique, additional study measuring the breach rate of pedicle screw placement in scoliosis is mandatory.

Materials and Methods

We performed a retrospective study of patients with adolescent idiopathic scoliosis (AIS) from Fatmawati General Hospital, Jakarta, treated for surgical correction during a period of 2017-2018 using free-hand technique for pedicle screw instrumentation. Post-operative computed tomography scan (CT scan) was analyzed to measure the medial and lateral breaches. P < 0.05 was deemed to be statistically significant.

Results

A total of 94 pedicle screws from six female patients with AIS were included in our study. Overall breach occurred in 33% instrumented screws, the majority of it was a low-grade breach. Of the breached screws, medial and lateral breach occurred in 20% and 12% of screws, respectively. There were no differences in the overall, medial, and lateral breaches between thoracic and lumbar vertebrae (P > 0.05). Medial breach was significantly higher in middle thoracic segment compared to other thoracic segments (P = 0.048). Risk of medial breach was 3 times higher in the convex side of deformity (P = 0.012), whereas risk of lateral breach was 4.6 times higher in the concave side of the deformity (P = 0.021).

Conclusion

The majority of breached screws were low-grade violation within the safe zone, with no neurological sequelae. Our study found that free-hand technique is safe and effective method of pedicle screw instrumentation for correction of AIS. Some inherent factors may influence the risk of pedicle screw breach.

Accuracy of fluoroscopic guidance with the coaxial view of the pedicle for percutaneous insertion of lumbar pedicle screws and risk factors for pedicle breach

OBJECTIVE

In this study the authors aimed to evaluate the rate of malposition, including pedicle breach and superior facet violation, after percutaneous insertion of pedicle screws using the coaxial fluoroscopic view of the pedicle, and to assess the risk factors for pedicle breach.

METHODS

In total, 394 percutaneous screws placed in 85 patients using the coaxial fluoroscopic view of the pedicle between January 2014 and September 2017 were assessed, and 445 pedicle screws inserted in 116 patients using conventional open procedures were used for reference. Pedicle breach and superior facet violation were evaluated by postoperative 0.4-mm slice CT.

RESULTS

Superior facet violation was observed in 0.5% of the percutaneous screws and 1.8% of the conventionally inserted screws. Pedicle breach occurred more frequently with percutaneous screws (28.9%) than with conventionally inserted screws (11.9%). The breaches in percutaneous screws were minor and did not reduce the interbody fusion rate. The angle difference between the percutaneous and conventionally inserted screws was comparable. Insertion at the L3 or L4 level, right-sided insertion, placement around a trefoil canal, smaller pedicle angle, and a small difference between the screw and pedicle diameters were found to be risk factors for pedicle breach by percutaneous pedicle screws.

CONCLUSIONS

Percutaneous pedicle screw placement using the coaxial fluoroscopic view of the pedicle carries a low risk of superior facet violation. The screws should be placed carefully considering the level and side of insertion, canal shape, and pedicle angle.

[A comparative study of robot-assisted and freehand pedicle screw placement in upper thoracic surgery]

OBJECTIVE

To compare the safety and accuracy of pedicle screw placement assisted by robot system with freehand pedicle screw placement in upper thoracic surgery.

METHODS

Between December 2017 and December 2019, 39 cases with upper thoracic pedicle screw internal fixation were included in the study, including 19 cases in robot group (group A, robot assisted pedicle screw placement) and 20 cases in freehand group (group B, freehand pedicle screw placement). There were 104 screws implanted in group A and 108 screws in group B. There was no significant difference in age, gender composition, body mass index, disease type, number of screws implanted, and segmental distribution between the two groups ( P>0.05). The operation time, intraoperative blood loss, and postoperative drainage were recorded and compared between the two groups. CT scan was performed in all patients at 2 days after operation to evaluate the screw accuracy based on the Gertzbein-Robbins grading standard.

RESULTS

The operation time of group A was significantly longer than that in group B ( t=2.759, P=0.009). There was no significant difference in intraoperative blood loss and postoperative drainage between the two groups ( t=-0.796, P=0.431; t=-0.814, P=0.421). At 2 days after operation, according to Gertzbein-Robbins grading standard, the accuracy of pedicle screw implantation in group A were grade A in 94 screws, grade B in 9 screws, and grade C in 1 screw; and in group B were grade A in 72 screws, grade B in 26 screws, grade C in 9 screws, and grade D in 1 screw; the difference between the two groups was significant ( Z=4.257, P=0.000). The accuracy rate of group A was 99.04%, and that of group B was 90.74%, showing significant difference ( χ 2=7.415, P=0.006).

CONCLUSION

Compared with traditional freehand pedicle screw placement, robot-assisted pedicle screw placement significantly improves the accuracy and safety of screw placement without increasing the bleeding and postoperative drainage.

Gold Nanoclusters for NIR-II Fluorescence Imaging of Bones

Fluorescence imaging in the second near-infrared window (NIR-II, 1000-1700 nm) holds great promise for deep tissue visualization. Development of novel clinical translatable NIR-II probes is crucial for realizing the medical applications of NIR-II fluorescence imaging. Herein, the glutathione-capped gold nanoclusters (AuNCs, specifically Au25 (SG)18 ) demonstrate highly efficient binding capability to hydroxyapatite in vitro for the first time. Further in vivo NIR-II fluorescence imaging of AuNCs indicate that they accumulate in bone tissues with high contrast and signal-background ratio. AuNCs are also mainly and quickly excreted from body through renal system, showing excellent ribs and thoracic vertebra imaging because of no background signal in liver and spleen. The deep tissue penetration capability and high resolution of AuNCs in NIR-II imaging render their great potential for fluorescence-guided surgery like spinal pedicle screw implantation. Overall, AuNCs are highly promising and clinical translatable NIR-II imaging probe for visualizing bone and bone related abnormalities.

Assessment of Surgical Procedural Time, Pedicle Screw Accuracy, and Clinician Radiation Exposure of a Novel Robotic Navigation System Compared With Conventional Open and Percutaneous Freehand Techniques: A Cadaveric Investigation

STUDY DESIGN

Cadaveric study.

OBJECTIVE

To evaluate accuracy, radiation exposure, and surgical time of a new robotic-assisted navigation (RAN) platform compared with freehand techniques in conventional open and percutaneous procedures.

METHODS

Ten board-certified surgeons inserted 16 pedicle screws at T10-L5 (n = 40 per technique) in 10 human cadaveric torsos. Pedicle screws were inserted with (1) conventional MIS technique (L2-L5, patient left pedicles), (2) MIS RAN (L2-L5, patient right pedicles), (3) conventional open technique (T10-L1, patient left pedicles), and (4) open RAN (T10-L1, patient right pedicles). Output included (1) operative time, (2) number of fluoroscopic images, and (3) screw accuracy.

RESULTS

In the MIS group, compared with the freehand technique, RAN allowed for use of larger screws (diameter: 6.6 ± 0.6 mm vs 6.3 ± 0.5 mm; length: 50.3 ± 4.1 mm vs 46.9 ± 3.5 mm), decreased the number of breaches >2 mm (0 vs 7), fewer fluoroscopic images (0 ± 0 vs 108.3 ± 30.9), and surgical procedure time per screw (3.6 ± 0.4 minutes vs 7.6 ± 2.0 minutes) (all P < .05). Similarly, in the open group, RAN allowed for use of longer screws (46.1 ± 4.1 mm vs 44.0 ± 3.8 mm), decreased the number of breaches >2 mm (0 vs 13), fewer fluoroscopic images (0 ± 0 vs 24.1 ± 25.8) (all P < .05), but increased total surgical procedure time (41.4 ± 8.8 minutes vs 24.7 ± 7.0 minutes, P = .000) while maintaining screw insertion time (3.31.4 minutes vs 3.1 ± 1.0 minutes, P = .650).

CONCLUSION

RAN significantly improved accuracy and decreased radiation exposure in comparison to freehand techniques in both conventional open and percutaneous surgical procedures in cadavers. RAN significantly increased setup time compared with both conventional procedures.

Retrospective analysis of pedicle screw accuracy for patients undergoing spinal surgery assisted by intraoperative computed tomography (CT) scanner AIRO® and BrainLab© navigation

Minimally invasive spine surgery techniques for pedicle screw instrumentation are being more frequently used. They offer shorter operative times, shorter hospital stays for patients, faster recovery, less blood loss, and less damage to surrounding tissues. However, they may rely heavily on fluoroscopic imaging, and confer radiation exposure to the surgeon and team members. Use of the AIRO Mobile Intraoperative CT by Brainlab during surgery is a way to eliminate radiation exposure to staff and may improve accuracy rates for pedicle screw instrumentation. We designed a retrospective analysis of our first 12 patients who had a total of 59 pedicle screws inserted when we began to incorporate the AIRO iCT scanner to our surgical workflow. During pedicle screw insertion, projection images were saved, and compared to CT scans gone at the end of the case. We measured the distances between the projected and postprocedural screw locations, at both the screw tips and tulip heads. We observed a mean of 2.8 mm difference between the projection and postprocedural images. None of the screws inserted had any clinically significant complications, and no patient required revision surgery. Overall, iCT guided navigation with the AIRO system is a safe adjunct to spinal surgery. It decreased operator and staff radiation exposure, and helped facilitate successful MIS surgery without fluoroscopic imaging. Additional studies and research can be done to further improve accuracy and reliability.

Increasing loads and diminishing returns: a biomechanical study of direct vertebral rotation

STUDY DESIGN

Biomechanical simulation of DVR and pure-moment testing on thoracic spines.

OBJECTIVES

Characterize load-deformation response of thoracic spines under DVR maneuvers until failure, and compare to pure-moment testing of same spines. Despite reports of surgical complications, few studies exist on increase in ROM under DVR torque. Biomechanical models predicting increases from surgical releases have consistently used "pure-moments", a standard established for non-destructive measurement of ROM. Yet, DVR torque is not accurately modeled using pure moments and, moreover, magnitudes of torque applied during DVR maneuvers may be substantially higher than pure-moment testing.

METHODS

Cadaveric thoracic spines (N = 11) were imaged, then prepared. Polyaxial pedicle screws were implanted at T7-T10 after surgical releases. Bilateral facetectomies and Ponte osteotomies were completed at T10-T11. A custom apparatus, mounted into an 8-dof MTS load frame, was used to attach to pedicle screws, allowing simulation of surgical DVR maneuvers. Motions of vertebrae were measured using optical motion tracking. Torque was increased until rupture of the T10-T11 disc or fracture at the pedicle screw sites at any level. The torque-rotation behavior was compared to its behavior under pure-moment testing performed prior to the DVR maneuver.

RESULTS

Under DVR maneuvers, failure of the T10-T11 discs accompanied in most cases by pedicle screw loosening, occurred at 13.7-54.7 Nm torque, increasing axial rotation by 1.4°-8.9°. In contrast, pure-moment testing (4 Nm) increased axial rotation by only 0.0°-0.9°.

CONCLUSIONS

DVR resulted in substantially greater correction potential increases compared to pure-moment testing even at the same torque. These results suggest increased flexibility obtained by osteotomies and facetectomies is underestimated using pure-moment testing, misrepresenting clinical expectations. The present study is an important and necessary step toward the establishment of a more accurate and ultimately surgically applied model.

LEVEL OF EVIDENCE

III.

Finding NEEMO: towards organizing smart digital solutions in orthopaedic trauma surgery

There are many digital solutions which assist the orthopaedic trauma surgeon. This already broad field is rapidly expanding, making a complete overview of the existing solutions difficult.The AO Foundation has established a task force to address the need for an overview of digital solutions in the field of orthopaedic trauma surgery.Areas of new technology which will help the surgeon gain a greater understanding of these possible solutions are reviewed.We propose a categorization of the current needs in orthopaedic trauma surgery matched with available or potential digital solutions, and provide a narrative overview of this broad topic, including the needs, solutions and basic rules to ensure adequate use in orthopaedic trauma surgery. We seek to make this field more accessible, allowing for technological solutions to be clearly matched to trauma surgeons' needs. Cite this article: EFORT Open Rev 2020;5:408-420. DOI: 10.1302/2058-5241.5.200021.

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.

Influence of a customized three-dimensionally printed drill guide on the accuracy of pedicle screw placement in lumbosacral vertebrae: An ex vivo study

OBJECTIVE

To compare the accuracy of pedicle screw insertion (PSI) into canine lumbosacral vertebrae with custom-made three-dimensionally (3D)-printed drill guides or freehand insertion.

STUDY DESIGN

Ex vivo study.

SAMPLE POPULATION

Nineteen canine lumbosacral specimens.

METHODS

Drill guides for PSI were designed on the basis of safe screw insertion trajectories by using preoperative computed tomography (CT) and produced by 3D printing of templates. Right and left sides of the specimens were randomly allocated to two groups; 4-mm pedicle screws were inserted in L5-L6 and L7-S1 spinal segments either freehand (control group) or with custom-made drill guides (guide group). Sixty-six screws were inserted with each method. Insertion angles (α, β), bone stock, and vertebral canal breach were assessed according to postoperative CT. χ² Tests were used to compare vertebral canal breach between groups and vertebrae.

RESULTS

Breaches in the vertebral canal were less common (P < .001) when screws were placed with a guide in the guide group (9/66, 14%) than without a guide (30/66, 45%). The rate of vertebral canal breach differed at L5 (P = .021) but not at L6 (P = .05), L7 (P = .075) or S1 (P = .658). The angle of insertion (α) did not differ between specimens with and without breaches (guide, P = .068; control, P = .394).

CONCLUSION

The use of a customized 3D-printed guide generally improved the accuracy of PSI in canine lumbosacral vertebrae, although statistical significance was reached only at L5.

CLINICAL SIGNIFICANCE

The use of customized drill guides may be considered as an alternative to freehand PSI in the lumbosacral area, especially for L5-L6 vertebrae.

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.

Reduced Puncture Time and Radiation Exposure of Percutaneous Transpedicular Puncture with Electronic Conductivity Device: A Randomized Clinical Trial

OBJECTIVES

The present study introduced an electronic conductivity device (ECD) to reduce time of percutaneous transpedicular puncture and frequency of patient valid radiation exposure in percutaneous kyphoplasty (PKP) or percutaneous vertebroplasty (PVP).

METHODS

A randomized self-control clinical study was undertaken. Medical records of patients with vertebral compression fractures (VCFs) for bilateral PKP or PVP were collected, and each side was performed randomly with ECD or conventional trocar.

RESULTS

We enrolled 61 patients (44 women, 17 men) with 75 vertebras with VCF. Compared with the conventional fluoroscopy group, significant reductions in puncture time (504.33 ± 152.03 vs. 652.68 ± 167.60 seconds; P < 0.001) and fluoroscopy frequency (5.11 ± 1.23 vs. 8.15 ± 1.83; P < 0.001) for each percutaneous puncture were observed in the ECD group. When compared with the VCFs ≤50% group, the 2 indexes in the VCFs >50% group were significantly increased. And in the ECD group, the learning curve in the VCFs >50% group showed a steeper decreasing trend than that in the VCFs ≤50% group. No complications were observed in any patient.

CONCLUSIONS

ECD could reduce puncture time of percutaneous transpedicular puncture and exposure of radiation in PVP and PKP. ECD has more benefits in complicated transpedicular puncture in patients with vertebral compression >50%.

New spinal robotic technologies

Robotic systems in surgery have developed rapidly. Installations of the da Vinci Surgical System® (Intuitive Surgical, Sunnyvale, CA, USA), widely used in urological and gynecological procedures, have nearly doubled in the United States from 2010 to 2017. Robotics systems in spine surgery have been adopted more slowly; however, users are enthusiastic about their applications in this subspecialty. Spinal surgery often requires fine manipulation of vital structures that must be accessed via limited surgical corridors and can require repetitive tasks over lengthy periods of time - issues for which robotic assistance is well-positioned to complement human ability. To date, the United States Food and Drug Administration (FDA) has approved 7 robotic systems across 4 companies for use in spinal surgery. The available clinical data evaluating their efficacy have generally demonstrated these systems to be accurate and safe. A critical next step in the broader adoption of surgical robotics in spine surgery is the design and implementation of rigorous comparative studies to interrogate the utility of robotic assistance. Here we discuss current applications of robotics in spine surgery, review robotic systems FDA-approved for use in spine surgery, summarize randomized controlled trials involving robotics in spine surgery, and comment on prospects of robotic-assisted spine surgery.

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.

Navigation versus experience: providing training in accurate lumbar pedicle screw positioning

PURPOSE

Accurate placement of spinal pedicle screws (PS) is mandatory for good primary segmental stabilization allowing consequent osseous fusion, requiring judgmental experience developed during a long training process. Computer navigation offers permanent visual control during screw manipulation and has been shown to significantly lower the risk of pedicle perforation. This study aims to evaluate whether safety, accuracy, and judgmental skills in screw placement, comparable to an experienced surgeon, can be developed during training using computer navigation.

METHODS

Lumbosacral PS were placed in 18 patients in a prospective setting, in one segment side with conventional fluoroscopy by a senior spine-surgeon, and computer navigated on the other side by a trainee without prior experience in the technique. At the beginning and at the end of the study, PS were placed freehand in solid foam models by the trainee. PS placement time, intraoperative placement revisions, PS placement accuracy on postoperative CT scans, and postoperative complications were assessed.

RESULTS

Significant improvement of trainee's PS placement accuracy (Sclafani score 8.2-8.83; p = 0.006) and time (13.3-6.8 min per screw; p = 0.005) to a similar level as the experienced surgeon state (5.2-4.1 min per screw; p = 0.39) was explored; similar improvement was explored in the foam models. The number of intraoperative placement revisions kept on a low level for surgeon (3.3-0.0%) and trainee (5.1-2.6%) during the whole study, no postoperative complications occurred.

CONCLUSION

Navigated PS insertion allows safe teaching from the early beginning of surgical training, due to steady intraoperative control on PS placement. Adequacy of PS placement is similar to screws placed by an experienced surgeon. Progress in judgmental skills in screw placement can be gained rapidly by the trainee, which can also be transferred to non-computer navigated PS placement.