Factors Affecting the Accuracy of Pedicle Screw Placement in Robot-Assisted Surgery: A Multicenter Study

Deviation from preoperative planning and pedicle screw accuracy in navigated and robotic spinal fusion: a systematic review

PURPOSE

Image-guided navigation and robotic systems have been introduced in spinal surgery to increase the accuracy of pedicle screws placement and reduce the rate of complications. The objective of this study is to evaluate the different final screw deviation from pre-operative planning and the associated pedicle screw accuracy in spinal fusion surgery assisted by image-guided navigation or robotic systems.

METHODS

The systematic literature search was executed using PubMed-Medline, Cochrane Central, and Scopus on 30 April 2023. Studies that explored the deviation between final position and preoperative planning of pedicle screws assisted by image-guide navigation or robotic system were included. The data extracted were surgical approach, surgical aid, number of screws evaluated, spinal levels, accuracy and deviation of screws. The quality of the studies was assessed using the revised Cochrane risk-of-bias tool for randomized trials (RoB 2) or the methodological index for non-randomized studies (MINORS) score.

RESULTS

This review included 15 studies, of which 5 used navigation and 10 robotic system. The studies involved 1487 patients, with the evaluation of a total of 7274 pedicle screws, with an assessment of planning and final position. The different methodologies to calculate the deviation include angular deviations in the axial and sagittal plane, 3D angular deviation, and tip and entry point deviation. Regarding screw accuracy, 98.15% of the screws were grade A or B, and 1.85% as category C or D.

CONCLUSION

Although preoperative planning allows the surgeon to plan the final position of the screw most appropriately, mild deviations from it do not seem to excessively influence the accuracy of the spinal fusion.

Robotic Spine Surgery: Systematic Review of Common Error Types and Best Practices

BACKGROUND AND OBJECTIVES

Robotic systems have emerged as a significant advancement in the field of spine surgery. They offer improved accuracy in pedicle screw placement and reduce intraoperative complications, hospital length of stay, blood loss, and radiation exposure. As the use of robotics in spine surgery continues to grow, it becomes imperative to understand common errors and challenges associated with this new and promising technology. Although the reported accuracy of robot-assisted pedicle screw placement is very high, the current literature does not capture near misses or incidental procedural errors that might have been managed during surgery or did not alter treatment of patients. We evaluated errors that occur during robot-assisted pedicle screw insertion and identify best practices to minimize their occurrence.

METHODS

In this systematic review, we characterized 3 types of errors encountered during robot-assisted pedicle screw insertion-registration errors, skiving, and interference errors-that have been reported in the literature.

RESULTS

Our search yielded 13 relevant studies reporting robot-assisted screw errors. Nine studies reported registration errors, with 60% of failed screws in those studies caused by registration issues. Seven studies highlighted skiving errors; 26.8% of the failed screws in those studies were caused by skiving. Finally, interference errors were reported in 4 studies, making up 19.5% of failed screws.

CONCLUSION

On the basis of these findings, we suggest best practices-including close attention to preoperative planning, patient positioning, image registration, and equipment selection-to minimize the occurrence of these errors. Awareness of how errors occur may increase the safety of this technology.

Advancing robot-guided techniques in lumbar spine surgery: a systematic review and meta-analysis

BACKGROUND

Lumbar spine surgery is a crucial intervention for addressing spinal injuries or conditions affecting the spine, often involving lumbar fusion through pedicle screw (PS) insertion. The precision of PS placement is pivotal in orthopedic surgery. This systematic review compares the accuracy of robot-guided (RG) surgery with free-hand fluoroscopy-guided (FFG), free-hand without fluoroscopy-guided (FHG), and computed tomography image-guided (CTG) techniques for PS insertion.

METHODS

A systematic search of various databases from 1 January 2013 to 30 December 2023 was conducted following PRISMA guidelines. Primary outcomes, including PS insertion accuracy and breach rate, were analyzed using a random-effects model. Risk of bias was assessed using the Newcastle-Ottawa Scale.

RESULTS

The overall accuracy of PS insertion using RG, based on 37 studies involving 3,837 patients and 22,117 PS, is 97.9%, with a breach rate of 0.021. RG demonstrated superior accuracy compared to FHG and CTG, with breach rates of 3.4 and 0.015 respectively for RG versus FHG, and 3.8 and 0.026 for RG versus CTG. Additionally, RG was associated with reduced mean estimated blood loss compared to CTG, indicating improved safety.

CONCLUSIONS

The RG is associated with enhanced accuracy of PS insertion and reduced breach rates over other methods. However, additional randomized controlled trials comparing these modalities are needed for further validation.

PROSPERO REGISTRATION

CRD42023483997.

Fully automated determination of robotic pedicle screw accuracy and precision utilizing computer vision algorithms

Historically, pedicle screw accuracy measurements have relied on CT and expert visual assessment of the position of pedicle screws relative to preoperative plans. Proper pedicle screw placement is necessary to avoid complications, cost and morbidity of revision procedures. The aim of this study was to determine accuracy and precision of pedicle screw insertion via a novel computer vision algorithm using preoperative and postoperative computed tomography (CT) scans. Three cadaveric specimens were utilized. Screw placement planning on preoperative CT was performed according to standard clinical practice. Two experienced surgeons performed bilateral T2-L4 instrumentation using robotic-assisted navigation. Postoperative CT scans of the instrumented levels were obtained. Automated segmentation and computer vision techniques were employed to align each preoperative vertebra with its postoperative counterpart and then compare screw positions along all three axes. Registration accuracy was assessed by preoperatively embedding spherical markers (tantalum beads) to measure discrepancies in landmark alignment. Eighty-eight pedicle screws were placed in 3 cadavers' spines. Automated registrations between pre- and postoperative CT achieved sub-voxel accuracy. For the screw tip and tail, the mean three-dimensional errors were 1.67 mm and 1.78 mm, respectively. Mean angular deviation of screw axes from plan was 1.58°. For screw mid-pedicular accuracy, mean absolute error in the medial-lateral and superior-inferior directions were 0.75 mm and 0.60 mm, respectively. This study introduces automated algorithms for determining accuracy and precision of planned pedicle screws. Our accuracy outcomes are comparable or superior to recent robotic-assisted in vivo and cadaver studies. This computerized workflow establishes a standardized protocol for assessing pedicle screw placement accuracy and precision and provides detailed 3D translational and angular accuracy and precision for baseline comparison.

Risk Factors of Screw Malposition in Robot-Assisted Cortical Bone Trajectory: Analysis of 1344 Consecutive Screws in 256 Patients

STUDY DESIGN

Retrospective single-center study using prospectively collected data.

OBJECTIVE

To describe the incidence of and identify risk factors for intraoperative screw malposition secondary to skive or shift during robot-assisted cortical bone trajectory (RA-CBT) insertion.

SUMMARY OF BACKGROUND DATA

RA-CBT screw malposition occurs through 2 distinct modes, skive or shift. Skive occurs when a downward force applied to the cannula, drill, tap, or screw, causes the instrument to deflect relative to its bony landmark. Shift is a change in the position of the RA system relative to the patient after registration.

PATIENTS AND METHODS

A consecutive series of patients older than 18 years who underwent RA-CBT screw placement between January 2019 and July 2022 were enrolled. Baseline demographic and surgical data, Hounsfield Units (HUs) at L1, and vertebral shape related to screw planning were collected. Skive or shift was recorded in the operating room on a data collection form.

RESULTS

Of 1344 CBT screws in 256 patients, malposition was recognized intraoperatively in 33 screws (2.4%) in 27 patients (10.5%); 19 through skive in 17 and 14 through shift in 10 patients. These patients had higher body mass index than patients without malposition (33.0 vs. 30.5 kg/m 2 , P = 0.037). Patients with skive had higher HU (178.2 vs . 145.2, P = 0.035), compared with patients with shift (139.2 vs . 145.2, P = 0.935) and patients without screw malposition. More than half of the screw malposition was observed at the upper instrumented vertebra. At the upper instrumented vertebra, if the screw's overlap to the bone surface at the insertion point was decreased, skive was more likely (57% vs . 87%, P < 0.001). No patients were returned to the operating room for screw revision.

CONCLUSIONS

Intraoperative screw malposition occurred in 2.4% of RA-CBT. High body mass index was associated with screw malposition, regardless of etiology. Skive was associated with high HU and decreased screw overlap to the bone surface at the insertion point.

Risk Factors for Medial Breach During Robotic-Assisted Cortical Bone Trajectory Screw Insertion

OBJECTIVE

We describe the incidence of, and identify the risk factors for, a medial breach of the pedicle wall during robotic-assisted cortical bone trajectory (RA-CBT) screw insertion.

METHODS

We analyzed a consecutive series of adult patients who underwent RA-CBT screw placement from January 2019 to July 2022. To assess the pedicle wall medial breach, postoperative computed tomography (CT) images were analyzed. Patient demographic data and screw data were compared between patients with and without a medial breach. The Hounsfield units (HUs) on the L1 midvertebral axial CT scan was used to evaluate bone quality.

RESULTS

Of 784 CBT screws in 145 patients, 30 (3.8%) had a medial breach in 23 patients (15.9%). One screw was grade 2, and the others were grade 1. Patients with a medial breach had a lower HU value compared with the patients without a medial breach (123.3 vs. 150.5; P = 0.027). A medial breach was more common in the right than left side (5.5% vs. 2.0%; P = 0.014). More than one half of the screws with a medial breach were found in the upper instrumented vertebra (UIV) compared with the middle construct or lowest instrumented vertebra (6.7% vs. 1.3% vs. 2.7%; P = 0.003). Binary logistic regression showed that low HU values, right-sided screw placement, and UIV were associated with a medial breach. No patients returned to the operating room for screw malposition. No differences were found in the clinical outcomes between patients with and without a medial breach.

CONCLUSIONS

The incidence of pedicle wall medial breach was 3.8% of RA-CBT screws in the postoperative CT images. A low HU value measured in the L1 axial image, right-sided screw placement, and UIV were associated with an increased risk of medial breach for RA-CBT screw placement.

Enhancing palliative care in vulnerable patients: Robot-assisted radiofrequency ablation for multiple spinal metastases - Technical insights and preliminary outcomes

Background

Radiofrequency thermal ablation (RFA) coupled with vertebroplasty or kyphoplasty offers a minimally invasive, safe, and efficacious approach to palliate polymetastatic spine disease, particularly in medically fragile individuals. However, the application of robotic assistance to RFA for spinal metastases remains unexplored. This study elucidates the technical viability of robot-assisted RFA combined with vertebroplasty in patients afflicted by multiple spinal metastases and presents preliminary outcomes. An illustrative case was also presented.

Materials and Methods

Ten patients aged over 65 years with multiple vertebral metastases were enrolled in this study. Preoperatively, patients exhibited a median Visual Analog Scale (VAS) pain score of 6 and a Median Oswestry Disability Index (ODI) score of 58%. From February 2021 to April 2022, all patients underwent RFA, followed by vertebroplasty for spinal metastases. Surgical procedures were executed using the ExcelsiusGPS® robotic platform.

Results

Patients experienced substantial pain relief, with a median VAS score of 2.5 at 24 h postoperatively (Δ --3.5; P < 0.001) and a median VAS score of 2 at 1 month postoperatively (Δ -4; P < 0.001). All patients were discharged on the first postoperative day and continued their oncological treatments. In addition, the median ODI score at 1 month postoperatively was 34% (Δ --24%; P = 0.006), indicating an enhanced quality of life and a satisfactory impact on daily activities. No procedural or postoperative complications were documented.

Conclusions

This case series represents the inaugural successful application of robot-assisted RFA in conjunction with concurrent vertebroplasty/kyphoplasty. Our preliminary experience demonstrates that patients with oligo- and polymetastatic conditions can derive benefits from this minimally invasive intervention, characterized by rapid postoperative recovery and effective short- to medium-term pain management, without encountering complications.