Accuracy and safety of robot-assisted cortical bone trajectory screw placement: a comparison of robot-assisted technique with fluoroscopy-assisted approach

Efficacy and Safety of Cortical Bone Trajectory Screws versus Pedicle Screws in Lumbar Fusion: A Systematic Review and Meta-Analysis

OBJECTIVE

A systematic review and meta-analysis was conducted to compare the efficacy and safety of cortical bone trajectory (CBT) screws and traditional pedicle screws in lumbar fusion.

METHODS

Randomized controlled studies and cohort studies on CBT versus pedicle screws in lumbar fusion were searched in China Biology Medicine, China National Knowledge Infrastructure, Wanfang, VIP Database for Chinese Technical and Science Periodicals, PubMed, Cochrane Library, and Web of Science databases. The search period spanned from the establishment of the databases to December 2023. The Cochrane bias risk assessment tool and Newcastle-Ottawa scale were applied to assess the quality of the literature included. Clinical and imaging data as well as surgical outcomes, recovery, and postoperative complications were extracted from the relevant literature.

RESULTS

A total of 6 randomized controlled trials and 26 cohort studies were included after screening by inclusion and exclusion criteria with a total of 2478 patients. The meta-analysis demonstrated significant discrepancies between the CBT and TPS groups in Japanese Orthopaedic Association score at 3 and 6 months and final follow-up. Moreover, the TPS group exhibited a higher Oswestry disability index at final follow-up, a greater VAS for low back pain at both 1 week and final follow-up, as well as a higher VAS for leg pain at 1 month. Differences were also noted in surgical and recovery outcomes. However, there was no significant difference between the 2 groups in postoperative complications.

CONCLUSIONS

CBT and TPS have analogous safety profiles when applied to lumbar fusion, but the clinical efficacy of CBT is superior to that of TPS to some extent, and the procedure is less invasive with faster recovery.

Development of a software system for surgical robots based on multimodal image fusion: study protocol

Background

Surgical robots are gaining increasing popularity because of their capability to improve the precision of pedicle screw placement. However, current surgical robots rely on unimodal computed tomography (CT) images as baseline images, limiting their visualization to vertebral bone structures and excluding soft tissue structures such as intervertebral discs and nerves. This inherent limitation significantly restricts the applicability of surgical robots. To address this issue and further enhance the safety and accuracy of robot-assisted pedicle screw placement, this study will develop a software system for surgical robots based on multimodal image fusion. Such a system can extend the application range of surgical robots, such as surgical channel establishment, nerve decompression, and other related operations.

Methods

Initially, imaging data of the patients included in the study are collected. Professional workstations are employed to establish, train, validate, and optimize algorithms for vertebral bone segmentation in CT and magnetic resonance (MR) images, intervertebral disc segmentation in MR images, nerve segmentation in MR images, and registration fusion of CT and MR images. Subsequently, a spine application model containing independent modules for vertebrae, intervertebral discs, and nerves is constructed, and a software system for surgical robots based on multimodal image fusion is designed. Finally, the software system is clinically validated.

Discussion

We will develop a software system based on multimodal image fusion for surgical robots, which can be applied to surgical access establishment, nerve decompression, and other operations not only for robot-assisted nail placement. The development of this software system is important. First, it can improve the accuracy of pedicle screw placement, percutaneous vertebroplasty, percutaneous kyphoplasty, and other surgeries. Second, it can reduce the number of fluoroscopies, shorten the operation time, and reduce surgical complications. In addition, it would be helpful to expand the application range of surgical robots by providing key imaging data for surgical robots to realize surgical channel establishment, nerve decompression, and other operations.

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.

Effectiveness and safety of robot-assisted versus fluoroscopy-assisted cortical bone trajectory screw instrumentation in spinal surgery: a systematic review and meta-analysis

Robot-assisted (RA) technology has been shown to be a safe aid in spine surgery, this meta-analysis aims to compare surgical parameters and clinical indexes between robot-assisted cortical bone trajectory (CBT) and fluoroscopy-assisted (FA) cortical bone trajectory in spinal surgery. We searched databases such as PubMed, Web of Science, the Cochrane Library, and the China National Knowledge Infrastructure. The study selection process was guided by the PICOS (Patient/Problem, Intervention, Comparison, Outcome, Study Design) strategy. The risk of bias in non-randomized comparative studies was assessed using the risk of bias in non-randomized studies of interventions (ROBINS-I) tool. We performed this meta-analysis using RevMan 5.3 software (Cochrane Collaboration, Copenhagen, Denmark), and the level of statistical significance was set at P < 0.05. Six articles involving 371 patients and 1535 screws were included in this meta-analysis. RA-CBT outperformed FA-CBT in terms of various parameters, such as accuracy of pedicle screw position (both Gertzbein-Robbins scale and Ding scale), avoidance of superior facet joint violation (FJV), and reduction of neurological injury. Our meta-analysis offered a thorough evaluation of the efficacy and safety of RA-CBT in spinal surgery. The findings revealed that RA-CBT produced statistically significant results in terms of pedicle screw position accuracy and superior facet joint violation prevention. In terms of surgical parameters and clinical indexes, future research and clinical practice should investigate the efficacy of RA-CBT further. The study was registered in the PROSPERO (CRD42023466280).

Robotic-Assisted Versus Fluoroscopic-Guided Surgery on the Accuracy of Spine Pedicle Screw Placement: A Systematic Review and Meta-Analysis

Spinal fusion is a common method by which surgeons decrease instability and deformity of the spinal segment targeted. Pedicle screws are vital tools in fusion surgeries and advancements in technology have introduced several modalities of screw placement. Our objective was to evaluate the accuracy of pedicle screw placement in robot-assisted (RA) versus fluoroscopic-guided (FG) techniques. The PubMed and Cochrane Library databases were systematically reviewed from January 2007 through to August 8, 2022, to identify relevant studies. The accuracy of pedicle screw placement was determined using the Gertzbein-Robbins (GR) classification system. Facet joint violation (FJV), total case radiation dosage, total case radiation time, total operating room (OR) time, and total case blood loss were collected. Twenty-one articles fulfilled the inclusion criteria. Successful screw accuracy (GR Grade A or B) was found to be 1.02 (95% confidence interval: 1.01 - 1.04) times more likely with the RA technique. In defining accuracy solely based on the GR Grade A criteria, screws placed with RA were 1.10 (95% confidence interval: 1.06 - 1.15) times more likely to be accurate. There was no significant difference between the two techniques with respect to blood loss (Hedges' g: 1.16, 95% confidence interval: -0.75 to 3.06) or case radiation time (Hedges' g: -0.34, 95% CI: -1.22 to 0.53). FG techniques were associated with shorter operating room times (Hedges' g: -1.03, 95% confidence interval: -1.76 to -0.31), and higher case radiation dosage (Hedges' g: 1.61, 95% confidence interval: 1.11 to 2.10). This review suggests that RA may slightly increase pedicle screw accuracy and decrease per-case radiation dosage compared to FG techniques. However, total operating times for RA cases are greater than those for FG cases.

Spine Surgical Robotics: Current Status and Recent Clinical Applications

With the development of artificial intelligence and the further deepening of medical-engineering integration, spine surgical robot-assisted (RA) technique has made significant progress and its applicability in clinical practice is constantly expanding in recent years. In this review, we have systematically summarized the majority of literature related to spine surgical robots in the past decade, and not only classified robots accordingly, but also summarized the latest research progress in RA technique for screw placement such as cervical, thoracic, and lumbar pedicle screws, cortical bone trajectory screws, cervical lateral mass screws, and S2 sacroiliac screws; guiding targeted puncture and placement of endoscope via the intervertebral foramen; complete resection of spinal tumor tissue; and decompressive laminectomy. In addition, this report also provides a detailed evaluation of RA technique's advantages and disadvantages, and clarifies the accuracy, safety, and practicality of RA technique. We consider that this review can help clinical physicians further understand and familiarize the current clinical application status of spine surgical robots, thereby promoting the continuous improvement and popularization of RA technique, and ultimately benefiting numerous patients.

The accuracy of cortical bone trajectory screw placement guided by spinous process clamp hardware in lumbar spinal surgery: a retrospective study

This study aimed to assess the accuracy of cortical bone trajectory (CBT) screws placement guided by a spinous process clamp (SPC) guide. A total of 32 patients who received single-level midline lumbar fusion (MIDLF) surgery between June 2019 and January 2020 were retrospectively analyzed and divided into free-hand (FH) and SPC-guided groups according to the surgical approach. In the FH group, CBT screws was implanted with the assistance of fluoroscopy, while in the SPC group, CBT screws was implanted using the SPC navigator hardwire. A total of 128 screws were assessed in this study, with higher rates of clinically acceptable screw placement (grades A and B) and grade A screws in the SPC group than in the FH guide group (92.2% vs. 79.7%, P = 0.042 and 54.7% vs. 35.9%, P = 0.033, respectively). Misplacement screws (grades C, D, and E) occurred more often in the FH group than in the SPC guide group (20.3% vs. 7.8%, P = 0.042). The incidence of proximal facet joint violation (FJV) was higher in the FH group than in the SPC group (15.6% vs. 3.1%, P = 0.030). The radiation dose and time in the SPC guide group were comparable to those in the FH group (P = 0.063 and P = 0.078). The average operative time was significantly longer in the SPC guide group than in the FH group (267.8 ± 45.5 min vs. 210.9 ± 44.5 min, P = 0.001). Other clinical parameters, such as the average bone mineral density (BMD), intraoperative blood loss, and postoperative hospital stay, were not significantly different. Oswestry disability index (ODI) and back pain visual analogue scale (VAS) scores were significantly improved in both groups compared with preoperatively. SPC guided screw placement was more accurate than the fluoroscopy-assisted FH technique for single-level MIDLF at L4/5. Patients undergoing SPC-guided screw placement can achieve similar clinical outcomes as the fluoroscopy-assisted FH technique.

Comparison of major spine navigation platforms based on key performance metrics: a meta-analysis of 16,040 screws

PURPOSE

The objective of this meta-analysis is to compare available computer-assisted navigation platforms by key performance metrics including pedicle screw placement accuracy, operative time, neurological complications, and blood loss.

METHODS

A systematic review was conducted using major databases for articles comparing pedicle screw accuracy of computer-assisted navigation to conventional (freehand or fluoroscopy) controls via post-operative computed tomography. Outcome data were extracted and pooled by random-effects model for analysis.

RESULTS

All navigation platforms demonstrated significant reduction in risk of breach, with Stryker demonstrating the highest accuracy compared to controls (OR 0.16 95% CI 0.06 to 0.41, P < 0.00001, I2 = 0%) followed by Medtronic. There were no significant differences in accuracy or most surgical outcome measures between platforms; however, BrainLab demonstrated significantly faster operative time compared to Medtronic by 30 min (95% CI - 63.27 to - 2.47, P = 0.03, I2 = 74%). Together, there was significantly lower risk of major breach in the navigation group compared to controls (OR 0.42, 95% CI 0.27-0.63, P < 0.0001, I2 = 56%).

CONCLUSIONS

When comparing between platforms, Stryker demonstrated the highest accuracy, and Brainlab the shortest operative time, both followed by Medtronic. No significant difference was found between platforms regarding neurologic complications or blood loss. Overall, our results demonstrated a 60% reduction in risk of major breach utilizing computer-assisted navigation, coinciding with previous studies, and supporting its validity. This study is the first to directly compare available navigation platforms offering insight for further investigation and aiding in the institutional procurement of platforms. LEVEL 3 EVIDENCE: Meta-analysis of Level 3 studies.

The Cortical Bone Trajectory Screw Technique Assisted by the Mazor Renaissance Robotic System as a Salvage Strategy for Failed Lumbar Spine Surgery: Technical Note and Case Series

Purpose

The objective of this study was to describe the Mazor Renaissance robotic system-assisted CBT (cortical bone trajectory) screw technique as a salvage strategy for failed lumbar spine surgery.

Patients and Methods

Between January 2018 and June 2022, 7 patients underwent salvage surgery with the CBT screw fixation technique assisted by the Mazor Renaissance robot system in our institution. Intraoperative observations were recorded for blood loss, duration of operation, and fluoroscopy time. Complications related to CBT screws were also recorded. The accuracy of CBT screws was recorded in accordance with the modified Gertzbein-Robbins classification. The JOA (Japanese Orthopedic Association) score for low back pain was used to evaluate surgical outcomes.

Results

A total of 26 CBT screws were placed in 7 patients, including 4 females and 3 males. Three patients underwent ASD (adjacent segment disease) and four patients underwent lumbar union failure with loose or compromised PSs (pedicle screws). The mean operation time was 129.29 ± 32.97 minutes, the mean blood loss was 180 ± 52.60 mL, and the mean intraoperative fluoroscopy time was 14.29 ± 3.15 s. All screws were clinically acceptable according to the Gertzbein-Robbins classification. There were no complications related to CBT screws in any of the cases. The JOA scores for low back pain of all patients were significantly improved at the final follow-up.

Conclusion

The CBT screw fixation technique supplemented the traditional PS fixation technique, which can be performed as a salvage strategy for failed lumbar spine surgery and achieved good clinical results. The spinal robot was very helpful in evaluating pedicle size and determining CBT screw direction, especially in a previously instrumented lumbar pedicle.

Robotics in spine surgery: systematic review of literature

PURPOSE

Over 4.83 million spine surgery procedures are performed annually around the world. With the considerable caseload and the precision needed to achieve optimal spinal instrumentation, technical progress has helped to improve the technique's safety and accuracy with the development of peri-operative assistance tools. Contrary to other surgical applications already part of the standard of care, the development of robotics in spine surgery is still a novelty and is not widely available nor used. Robotics, especially when coupled with other guidance modalities such as navigation, seems to be a promising tool in our quest for accuracy, improving patient outcomes and reducing surgical complications. Robotics in spine surgery may also be for the surgeon a way to progress in terms of ergonomics, but also to respond to a growing concern among surgical teams to reduce radiation exposure.

METHOD

We present in this recent systematic review of the literature realized according to the PRISMA guidelines the place of robotics in spine surgery, reviewing the comparison to standard techniques, the current and future indications, the learning curve, the impact on radiation exposure, and the cost-effectiveness.

RESULTS

Seventy-six relevant original studies were identified and analyzed for the review.

CONCLUSION

Robotics has proved to be a safe help for spine surgery, both for the patient with a decrease of operating time and increase in pedicular screw accuracy, and for the surgical team with a decrease of radiation exposure. Medico-economic studies demonstrated that despite a high buying cost, the purchase of a robot dedicated for spine surgery is cost-effective resulting in lesser revision, lower infection, reduced length of stay, and shorter surgical procedure.

Comparison of CT values in traditional trajectory, traditional cortical bone trajectory, and modified cortical bone trajectory

BACKGROUND

To compare the CT values and length of the screw tracks of traditional trajectory (TT), cortical bone trajectory (CBT), and modified cortical bone trajectory (MCBT) screws and investigate the effects on the biomechanics of lumbar fixation.

METHODS

CT scan data of 60 L4 and L5 lumbar spine were retrieved and divided into 4 groups (10 male and 10 female cases in the 20-30 years old group and 20 male and 20 female cases in the 30-40 years old group). 3-dimentional (3D) model were established using Mimics 19.0 for each group and the placement of three techniques was simulated on the L4 and L5, and the part of the bone occupied by the screw track was set as the region of interest (ROI). The mean CT value and the actual length of the screw track were measured by Mimics 19.0.

RESULTS

The CT values of ROI for the three techniques were significantly different between the same gander in each age group (P < 0.05). The difference of screw track lengths for CBT and MCBT in the male and female is significant (P < 0.05).

CONCLUSIONS

According to the CT values of the three screw tracks: MCBT > CBT > TT, the MCBT screw track has greater bone-screw surface strength and longer screw tracks than CBT, which is easier to reach the anterior column of the vertebral body contributing to superior biomechanical properties.

Accuracy and Screw Insertion Time of Robotic-Assisted Cortical Bone Trajectory Screw Placement for Posterior Lumbar Interbody Fusion: A Comparison of Early, Middle, and Late Phases

Introduction The purpose of this study was to evaluate robotic-assisted cortical bone trajectory (CBT) screw placement. Early, middle, and late phases of robotic-assisted CBT screw placement were compared for accuracy and screw insertion time by comparing time and accuracy in every phase.  Methods A retrospective review was conducted on the initial 40 patients who underwent spinal fusion using CBT screws in one institution from September 2021 to September 2022 utilizing a spine surgery robot system (Mazor X Stealth Edition, Medtronic Inc., Dublin, Ireland). The inclusion criterion was one- or two-level posterior lumbar interbody fusion (PLIF). Exclusion criteria were 1) patients who underwent posterior-lateral fusion in other segments, 2) patients who underwent additional decompression in other segments, 3) patients who underwent reoperation, and 4) patients with spondylolysis. The deviation of the CBT screw was evaluated on computed tomography (CT) one week after surgery using the Gertzbein-Robbins grade system. The rate of Grade A was considered the perfect accuracy rate, and the rate of penetration of 2 mm or more (Grades C, D, and E) was calculated as the deviation rate. To assess the learning curve, patients were divided into three groups. The first 10 cases were in the early phase group, the subsequent 10 cases were in the middle phase group, and the last 10 cases were in the late phase group. We compared the perfect accuracy rate, deviation rate, operative time, operative time per segment, intraoperative blood loss, registration time, and screw insertion time among the three groups. Results Thirty patients met the criteria. Overall, the perfect accuracy (Grade A) rate of the screw was 95.3% and the deviation rate was 1.4%. The perfect accuracy rate was 90.4% in the early phase, 95.5% in the middle phase, and 100% in the late phase. The deviation rate was 3.8% in the early phase, 0% in the middle phase, and 0% in the late phase, and there was no statistically significant difference between the three groups. Among the three groups, the operative time, the operative time per segment, the intraoperative blood loss, and the registration time were not significantly different. There was no significant difference in the screw insertion time among the three groups, but it decreased with experience (early phase: 156.9 ± 54.7 sec, middle phase: 139.9 ± 41.6 sec, and late phase: 106.4 ± 39.9 sec, p=0.060). The screw insertion time of the late phase tended to be shorter than that of the early phase (p=0.052). Conclusions The deviation rate of robotic-assisted CBT screw placement with one- or two-level PLIF was 1.4%, which was highly accurate. The deviation rate was 3.8% in the early phase, 0% in the middle phase, and 0% in the late phase. Although the deviation rate was low even in the early period, the screw insertion time in the early 10 cases tended to be longer than that in the late 10 cases. After passing the experience of 10 cases, this study concluded that robotic-assisted CBT screw placement was proficient.

Development and Clinical Trial of a New Orthopedic Surgical Robot for Positioning and Navigation

Robot-assisted orthopedic surgery has great application prospects, and the accuracy of the robot is the key to its overall performance. The aim of this study was to develop a new orthopedic surgical robot to assist in spinal surgeries and to compare its feasibility and accuracy with the existing orthopedic robot. A new type of high-precision orthopedic surgical robot (Tuoshou) was developed. A multicenter, randomized controlled trial was carried out to compare the Tuoshou with the TiRobot (TINAVI Medical Technologies Co., Ltd., Beijing) to evaluate the accuracy and safety of their navigation and positioning. A total of 112 patients were randomized, and 108 patients completed the study. The position deviation of the Kirschner wire placement in the Tuoshou group was smaller than that in the TiRobot group (p = 0.014). The Tuoshou group was better than the TiRobot group in terms of the pedicle screw insertion accuracy (p = 0.016) and entry point deviation (p < 0.001). No differences were observed in endpoint deviation (p = 0.170), axial deviation (p = 0.170), sagittal deviation (p = 0.324), and spatial deviation (p = 0.299). There was no difference in security indicators. The new orthopedic surgical robot was highly accurate and optimized for clinical practice, making it suitable for clinical application.