Size selection and placement of pedicle screws using robot-assisted versus fluoroscopy-guided techniques for thoracolumbar fractures: possible implications for the screw loosening rate

Is Force Control a Safe and Efficient Surgical Technology for Thoracolumbar Fusion Surgery? A Post Market Clinical Follow-Up Study

BACKGROUND

Early screw loosening, a relevant complication after posterior thoracolumbar fusion, indicates high mechanical stress during rod connection. Force Control is a surgical technology that goes beyond the usual to identify, control, and minimize intended and unintended, usually unnoticed forces to achieve the most stressless fixation. Optimized, extremely lightweight instruments support this principle on part of the pedicle screw system (PSS). The study objective is to evaluate the safety and efficacy of a novel PSS for Force Control fusion surgery.

METHODS

In this literature-controlled observational study, patients underwent surgery with a PSS that supports Force Control. Safety is demonstrated 1 year postoperatively by noninferiority in screw loosening rate and efficacy by noninferiority in Oswestry Disability Index (ODI) improvement. Secondary endpoints: 2-year ODI, spine-related adverse events, and outcomes. Statistical significance: P < 0.025 (Bonferroni correction 0.05/2).

RESULTS

75 patients enrolled, main diagnoses were trauma (73.3%), spinal stenosis (17.3%), and degenerative disc disease (6.7%). Screw loosening rate at 1 year was 2.7%, being not inferior (P = 0.005) to the control group at 9.2%. Mean ODI improvement of 49.3 showed noninferiority (P < 0.001) versus 35.2 in the control group. Mean 2-year ODI was 19, mean visual analog scale back pain improved from 80.3 to 24.1 (3 months) and 21.6 (1 year). The implant-related revision rate was 4.1%.

CONCLUSIONS

Force Control, aiming to go beyond the familiar by controlling intended and unintended forces to achieve the most stressless fixation, is a safe and efficient method. Lightweight instruments are designed to allow identifying, controlling, and reducing mechanical stress. Patients benefit from Force Control regarding screw loosening and clinical outcome.

[Advances in MRI-based bone quality scoring systems and their clinical applications]

Objective

To summarize the advances in MRI-based bone quality scoring systems and their clinical applications.

Methods

A comprehensive literature review was conducted on recent studies related to the MRI-based bone quality scoring system, focusing on measurement methods, influencing factors, and clinical significance.

Results

Osteoporosis has a high incidence in China, significantly impacting patients' quality of life and the postoperative outcomes of related orthopedic surgeries. Early identification of osteoporosis holds important clinical significance. In recent years, both domestic and international research has enriched the MRI-based bone quality scoring systems, which includes vertebral bone quality scoring, endplate bone quality scoring, and pedicle bone quality scoring. Compared to the "gold standard" of bone density measurement, dual-energy X-ray absorptiometry, the bone quality scoring systems demonstrate good efficacy in identifying abnormal bone mass and predicting postoperative complications, while being less influenced by degenerative changes in the lumbar spine, indicating its important clinical application value.

Conclusion

The MRI-based bone quality scoring systems have good value in clinical applications. However, current studies are mostly retrospective cohort and case-control studies, which carry a risk of bias. The clinical application value needs further clarification through meta-analysis and large-scale prospective studies.

Current status and prospects of robot-assisted spine surgery

INTRODUCTION

Traditional spine surgery is frequently impeded by a number of challenges, including the complexity of the underlying anatomy, the depth of the surgical locations, and the limited visibility. These factors can collectively result in prolonged operation times and a reduction in the precision. The advent of robot-assisted spine surgery has brought about a transformative solution, particularly in the context of screw placement. Robot-assisted spine surgery has the potential to enhance accuracy and safety while minimizing soft tissue damage.

AREAS COVERED

This article presents a review of the current state of robot systems in spine surgery. The principal advantages of robot-assisted technology include high precision in screw placement, robust imaging capabilities, reduced surgeon fatigue, and the potential for remote operation, thereby addressing disparities in healthcare access. Clinical studies indicate that robot-assisted techniques significantly improve the accuracy of screw placement and may reduce the incidence of postoperative complications. Challenges such as cost, technology limitations, and the need for comprehensive clinical guidelines persist.

EXPERT OPINION

It is anticipated that future advancements in surgical navigation, artificial intelligence integration and the expansion of robot functions will further enhance the efficacy of robot-assisted spine surgery, with the potential to improve patient outcomes and facilitate broader adoption in clinical practice.

The Correlation Analysis Between the Pedicle Screw Placement Palpation and Torque

BACKGROUND

This study endeavored to investigate the influencing factors of pedicle screw torque measured during surgery and the correlation between manual palpation scores and screw torque.

METHODS

This investigation was a prospective study designed to gather data from patients who underwent spinal internal fixation performed by the same surgical team at the Department of Orthopedics, affiliated with the First Hospital of Guangzhou University of Chinese Medicine, spanning from January 2020 to September 2023. The sample comprised 51 individuals (18 males and 33 females; mean age: 60.78±11.48 years). All participants underwent bone mineral density (BMD) and comprehensive radiological testing to evaluate the affected spinal segments. Intraoperatively, parameters such as the surgeon's tactile perception, a visual analog scale for manual palpation, and peak screw torque values were documented. Patients were subsequently stratified into 3 categories based on the resistance encountered during screw placement. Demographic variables (age, height, and weight) and BMD measurements of patients within each category were compared. Factors exhibiting significant differences were subjected to multivariate logistic regression analysis. Concurrently, the relationship between manual palpation scores and torque values was examined.

RESULTS

The results of the univariate analysis indicated that age (P = 0.042), height (P = 0.047), BMD of the lumbar (P < 0.01), BMD of the femoral neck (P = 0.02), BMD of the hip (P = 0.02), and P1NP (P = 0.044) were statistically significant. The results of multivariate logistic regression analysis revealed that BMD of the lumbar was an independent influencing factor for torque (P=0.000<0.05). Additionally, the manual palpation score and torque value of group A were significantly lower than those of the other 2 groups (P < 0.001). There was a significant positive correlation between the intraoperative screw placement palpation and torque.

CONCLUSIONS

The BMD of the lumbar is an independent factor that influences the measured torque applied to pedicle screws during surgery. A significant and robust positive correlation exists between the intraoperative screw placement tactile sensation and the torque experienced. It is advisable to reinforce the screw channel with bone cement when the tactile score is ≤2.5 and the torque is ≤ 1.3 Nm.

Accuracy of Percutaneous Pedicle Screw Placement Using Modified Single Anterior-Posterior Fluoroscopy with the C-Arm for the Treatment of Traumatic Thoracic and Lumbar Fractures

OBJECTIVE

We aimed to assess percutaneous pedicle screw (PPS) placement accuracy, fluoroscopy shot number, and operation time using a modified single anterior-posterior (AP) fluoroscopy with a C-arm in treating traumatic thoracic and lumbar vertebral fractures.

METHODS

In total, 164 patients with single-level traumatic thoracic or lumbar fracture who underwent 6 PPS placements between April 2018 and September 2020 were divided into 2 groups. Conventional AP combined lateral fluoroscopy was used in Group A, whereas modified single AP fluoroscopy was used in Group B. The accuracy of the PPS placement, number of fluoroscopy shots, and operation time were compared. All patients underwent computed tomography 2-4 days after surgery to evaluate screw position. Pedicle breach was divided into 4 grades based on postoperative computed tomography.

RESULTS

Our study included 984 implanted pedicle screws, of which 36 (3.7%) were malpositioned. The breach rate was 3.5% (grade 1, 3.1%; grade 2, 0.4%) in Group A and 3.7% (grade 1, 3.0%; grade 2, 0.8%) in Group B. The median number of fluoroscopy shots during PPS placement was 21.9 in Group A and 8.4 in Group B. The median operation time was 76.07 ± 6.86 minutes in Group A and 55.78 ± 7.21 minutes in Group B.

CONCLUSIONS

The PPS placement method using modified single AP fluoroscopy for treating traumatic thoracic and lumbar spine fractures was fairly accurate and reduced the number of fluoroscopy shots and operation time. This technique requires only a C-arm for assistance and can be easily mastered by spinal surgeons across hospitals of various levels.

MRI-based pedicle bone quality score: correlation to quantitative computed tomography bone mineral density and its role in quantitative assessment of osteoporosis

BACKGROUND CONTEXT

Bone quality in the pedicle region generally determines screw pullout strength, insertion torque, and vertebral body loading characteristics. Dual-energy X-ray absorptiometry (DEXA), as the gold standard for evaluating bone mineral density (BMD), cannot measure the BMD of specific parts, such as pedicle, and DEXA is limited in many ways. Recent studies have shown a correlation between the magnetic resonance imaging (MRI)-based vertebral bone quality (VBQ) score and BMD measured using DEXA or quantitative computed tomography (QCT). However, no studies have been reported on the MRI-based pedicle bone quality (PBQ) score. Moreover, few studies have investigated the relationship between MRI-based PBQ and osteoporosis.

PURPOSE

To create a new site-specific MRI-based PBQ assessment method and assess its diagnostic capacity in patients with normal BMD and osteopenia/osteoporosis.

STUDY DESIGN/SETTING

A retrospective study.

PATIENT SAMPLE

A total of 156 patients underwent lumbar fusion surgery for chronic low back pain at our hospital between 2021 and 2022, with lumbar QCT and T1-weighted MRI performed before surgery.

OUTCOME MEASURES

Correlation of the PBQ score with QCT BMD, and the association between the PBQ score and presence of osteopenia/osteoporosis.

METHODS

BMD of the lumbar was calculated as the mean BMD of the L1 and L2 vertebral bodies on the basis of asynchronous QCT measurements. The PBQ score, which is the average of the bone quality values of both pedicles on the basis of site-specific T1-weighted sagittal MRI images, was calculated by dividing the median signal intensity of the L1-L4 pedicles by the signal intensity of the cerebrospinal fluid at the L3 level. The interobserver reliability of the PBQ score was assessed using the intraclass correlation coefficient (ICC). A receiver operating characteristic curve was drawn, and the area under the curve (AUC) was calculated to assess the predictive performance of PBQ for osteoporosis. The PBQ score was compared with QCT BMD, as the gold standard, using Pearson correlation analysis.

RESULTS

In total, 156 patients participated in this study, including 51 in the Normal BMD group and 105 in the osteopenia/osteoporosis group. The PBQ score in the osteopenia/osteoporosis group was significantly higher than that in the normal BMD group (3.19±0.55 vs 2.84±0.51, p<.001). The VBQ and PBQ scores were calculated by 2 authors and were in good agreement (intraclass correlation coefficient=0.949 and 0.929, respectively). Pearson's test showed a significant negative correlation between PBQ and QCT BMD (r=-0.4887, p<.001). The optimal cutoff PBQ score to differentiate patients with osteopenia/osteoporosis from those with normal BMD was 3.160, with a sensitivity of 66.7%, specificity of 72.5%, and AUC of 0.776. The PBQ score correlated more strongly with QCT BMD (r=-0.4887) than VBQ (r=-0.4078).

CONCLUSIONS

In this study, we propose a novel, MRI-based pedicle-specific bone quality score. This is the first study to investigate the relationship between the PBQ score and QCT BMD. The PBQ score showed diagnostic utility, differentiating between patients with osteopenia/osteoporosis and those with normal BMD (AUC=0.776), and the PBQ score correlated more strongly with QCT BMD than VBQ.

Novel MRI-Based Pedicle Bone Quality Score Independently Predicts Pedicle Screw Loosening after Degenerative Lumbar Fusion Surgery

Pedicle screw loosening after posterior lumbar fusion is associated with poor bone quality, which often determines screw pull-out strength, insertion torque, and vertebral body loading characteristics. Magnetic resonance imaging (MRI)-based vertebral bone quality (VBQ) score were associated with poor bone quality. Current evidence suggests that pedicle bone quality (PBQ) has a greater impact on screw stability. However, the correlation between MRI-based PBQ score and screw loosening has not been reported.

PURPOSE

To introduce and evaluate an MRI-based PBQ score to determine its effectiveness in predicting pedicle screw loosening following lumbar fusion surgery.

METHODS

The retrospective study analyzed 244 patients who underwent posterior lumbar interbody fusion (PLIF) with pedicle screws between December 2017 and December 2021, with CT and MRI imaging before surgery. Data collected included patient demographics and preoperative radiological data. Radiographic screw loosening was measured at 12 months postoperatively. Clinical assessments included pain visual analog scale (VAS) and Oswestry Disability Index (ODI) scores. The PBQ score was measured using MRI scans. We use univariate analysis for preliminary screening of the risk factors of screw loosening. Subsequent analysis involved multivariate logistic regression to identify independent predictive factors for screw loosening. We constructed the receiver operating characteristic (ROC) curve to ascertain the discriminative capacity of the PBQ score. The area under the curve (AUC) quantified its predictive accuracy. Additionally, we evaluated the association between PBQ score and screw loosening using Spearman's correlation analysis.

RESULTS

Overall, 244 patients who underwent PLIF with pedicle screw fixation participated in this study, including 35 in the loosening group and 209 in the non-loosening group. PBQ score in the loosening group was significantly higher than that in the non-loosening group. On multivariate logistic regression, the higher PBQ score (OR = 8.481, 95% CI: 3.158-22.774; p < 0.001) and the lower mean Hounsfield unit (HU) value of L1-4 (OR = 0.967, 95% CI 0.951-0.984; p < 0.001) were the variables that significantly predicted screw loosening. The AUC for the PBQ score and HU value were 0.751 (95% CI: 0.673-0.828) and 0.702 (95% CI: 0.612-0.791). The PBQ score optimal cutoff to differentiate patients with loosening and with non-loosening was calculated as 3.045 with a sensitivity of 85.7% and specificity of 76.9%, while the optimal cutoff of the HU value was 151.5 with a sensitivity of 64.6% and specificity of 89.5%.

CONCLUSIONS

The association between the PBQ score and the propensity for lumbar pedicle screw loosening was found to be substantial. As a predictive measure, the PBQ score outperformed the HU value in forecasting the likelihood of screw loosening post-posterior lumbar fusion.

Surgical outcomes of robotic-assisted percutaneous fixation for thoracolumbar fractures in patients with ankylosing spondylitis

BACKGROUND

Spinal fractures in patients with ankylosing spondylitis (AS) mainly present as instability, involving all three columns of the spine, and surgical intervention is often considered necessary. However, in AS patients, the significant alterations in bony structure and anatomy result in a lack of identifiable landmarks, which increases the difficulty of pedicle screw implantation. Therefore, we present the clinical outcomes of robotic-assisted percutaneous fixation for thoracolumbar fractures in patients with AS.

METHODS

A retrospective review was conducted on a series of 12 patients diagnosed with AS. All patients sustained thoracolumbar fractures between October 2018 and October 2022 and underwent posterior robotic-assisted percutaneous fixation procedures. Outcomes of interest included operative time, intra-operative blood loss, complications, duration of hospital stay and fracture union. The clinical outcomes were assessed using the visual analogue scale (VAS) and Oswestry Disability Index (ODI). To investigate the achieved operative correction, pre- and postoperative radiographs in the lateral plane were analyzed by measuring the Cobb angle.

RESULTS

The 12 patients had a mean age of 62.8 ± 13.0 years and a mean follow-up duration of 32.7 ± 18.9 months. Mean hospital stay duration was 15 ± 8.0 days. The mean operative time was 119.6 ± 32.2 min, and the median blood loss was 50 (50, 250) ml. The VAS value improved from 6.8 ± 0.9 preoperatively to 1.3 ± 1.0 at the final follow-up (P < 0.05). The ODI value improved from 83.6 ± 6.1% preoperatively to 11.8 ± 6.6% at the latest follow-up (P < 0.05). The average Cobb angle changed from 15.2 ± 11.0 pre-operatively to 8.3 ± 7.1 at final follow-up (P < 0.05). Bone healing was consistently achieved, with an average healing time of 6 (5.3, 7.0) months. Of the 108 screws implanted, 2 (1.9%) were improperly positioned. One patient experienced delayed nerve injury after the operation, but the nerve function returned to normal upon discharge.

CONCLUSION

Posterior robotic-assisted percutaneous internal fixation can be used as an ideal surgical treatment for thoracolumbar fractures in AS patients. However, while robot-assisted pedicle screw placement can enhance the accuracy of pedicle screw insertion, it should not be relied upon solely.

Comparison of 3D-navigation and fluoroscopic guidance in percutaneous pedicle screw placement for traumatic fractures of the thoracolumbar junction

Introduction

Fractures of the thoracolumbar junction are the most common vertebral fractures and can require surgical treatment. Several studies have shown that the accuracy of pedicle screw placement can be improved by the use of 3D-navigation. Still only few studies have focused on the use of navigation in traumatic spine injuries.

Research question

The aim of this study was to compare the screw placement accuracy and radiation exposure for 3D-navigated and fluoroscopy-guided percutaneous pedicle screw placement in traumatic fractures of the thoracolumbar junction.

Materials and methods

In this single-center study 25 patients undergoing 3D-navigated percutaneous pedicle screw placement for traumatic fractures of the thoracolumbar junction (T12-L2) were compared to a control group of 25 patients using fluoroscopy. Screw accuracy was determined in postoperative CT-scans using the Gertzbein-Robbins classification system. Additionally, duration of surgery, dose area product, fluoroscopy time and intraoperative complications were compared between the groups.

Results

The accuracy of 3D-navigated percutaneous pedicle screw placement was 92.66 % while an accuracy of 88.08 % was achieved using standard fluoroscopy (p = 0.19). The fluoroscopy time was significantly less in the navigation group compared to the control group (p = 0.0002). There were no significant differences in radiation exposure, duration of surgery or intraoperative complications between the groups.

Discussion and conclusion

The results suggest that 3D-navigation facilitates higher accuracy in percutaneous pedicle screw placement of traumatic fractures of the thoracolumbar junction, although limitations should be considered. In this study 3D-navigation did not increase fluoroscopy time, while radiation exposure and surgery time were comparable.

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.

Implications of navigation in thoracolumbar pedicle screw placement on screw accuracy and screw diameter/pedicle width ratio

Introduction

There is ample evidence that higher accuracy can be achieved in thoracolumbar pedicle screw placement by using spinal navigation. Still, to date, the evidence regarding the influence of the use of navigation on the screw diameter to pedicle width ratio remains limited.

Research question

The aim of this study was to investigate the implications of navigation in thoracolumbar pedicle screw placement not only on screw accuracy, but on the screw diameter to pedicle width ratio as well.

Material and methods

In this single-center single-surgeon study, 45 Patients undergoing navigated thoracolumbar pedicle screw placement were prospectively included. The results were compared with a matched comparison group of patients in which screw placement was performed under fluoroscopic guidance. The screw accuracy and the screw diameter to pedicle width ratio of every screw were compared between the groups.

Results

Screw accuracy was significantly higher in the navigation group compared to the fluoroscopic guidance group, alongside with a significant increase of the screw diameter to pedicle width ratio by approximately 10%. In addition, both the intraoperative radiation dose and the operating time tended to be lower in the study group.

Conclusion

This study was able to show that navigated thoracolumbar pedicle screw placement not only increases the accuracy of screw placement but also facilitates the selection of the adequate screw sizes, which according to the literature has positive effects on fixation strength. Meanwhile, the use of navigation did not negatively affect the time needed for surgery or the patient's intraoperative exposure to radiation.

The Child's Age and the Size of the Curvature Do Not Affect the Accuracy of Screw Placement with the Free-Hand Technique in Spinal Deformities in Children and Adolescents

BACKGROUND

The current method of treatment of spinal deformities would be almost impossible without pedicle screws (PS) placement. There are only a few studies evaluating the safety of PS placement and possible complications in children during growth. The present study was carried out to evaluate the safety and accuracy of PS placement in children with spinal deformities at any age using postoperative computed tomography (CT) scans.

METHODS

318 patients (34 males and 284 females) who underwent 6358 PS fixations for pediatric spinal deformities were enrolled in this multi-center study. The patients were divided into three age groups: less than 10 years old, 11-13 years old, and 14-18 years old. These patients underwent postoperative CT scans and were analyzed for pedicle screw malposition (anterior, superior, inferior, medial, and lateral breaches).

RESULTS

The breach rate was 5.92% for all pedicles. There were 1.47% lateral and 3.12% medial breaches for all pedicles with tapping canals, and 2.66% lateral and 3.84% medial breaches for all pedicles without a tapping canal for the screw. Of the 6358 screws placed in the thoracic, lumbar, and sacral spine, 98% of the screws were accurately placed (grade 0, 1, and juxta pedicular). A total of 56 screws (0.88%) breached more than 4 mm (grade 3), and 17 (0.26%) screws were replaced. No new and permanent neurological, vascular, or visceral complications were encountered.

CONCLUSIONS

The free-hand technique for pedicle screw placement in the acceptable and safety zone in pedicles and vertebral bodies was 98%. No complications associated with screw insertion in growth were noted. The free-hand technique for pedicle screw placement can be safely used in patients at any age. The screw accuracy does not depend on the child's age nor the size of the deformity curve. Segmental instrumentation with posterior fixation in children with spinal deformities can be performed with a very low complication rate. Navigation of the robot is only an auxiliary tool in the hands of the surgeons, and the result of the work ultimately depends on the surgeons.