Percutaneous pedicle screw placements: accuracy and rates of cranial facet joint violation using conventional fluoroscopy compared with intraoperative three-dimensional computed tomography computer navigation

Top 25 Most Cited Articles on Intraoperative Computer Tomography-Guided Navigation in Spine Surgery

BACKGROUND

In recent years, the use of intraoperative computer tomography-guided (CT-guided) navigation has gained significant popularity among health care providers who perform minimally invasive spine surgery. This review aims to identify and analyze trends in the literature related to the widespread adoption of CT-guided navigation in spine surgery, emphasizing the shift from conventional fluoroscopy-based techniques to CT-guided navigation.

METHODS

Articles pertaining to this study were identified via a database review and were hierarchically organized based on the number of citations. An "advanced document search" was performed on September 28th, 2022, utilizing Boolean search operator terms. The 25 most referenced articles were combined into a primary list after sorting results in descending order based on the total number of citations.

RESULTS

The "Top 25" list for intraoperative CT-guided navigation in spine surgery cumulatively received a total of 2742 citations, with an average of 12 new citations annually. The number of citations ranged from 246 for the most cited article to 60 for the 25th most cited article. The most cited article was a paper by Siewerdsen et al., with 246 total citations, averaging 15 new citations per year.

CONCLUSIONS

Intraoperative CT-guided navigation is 1 of many technological advances that is used to increase surgical accuracy, and it has become an increasingly popular alternative to conventional fluoroscopy-based techniques. Given the increasing adoption of intraoperative CT-guided navigation in spine surgery, this review provides impactful evidence for its utility in spine surgery.

The Utility and Appropriateness of Single-Position Circumferential Lumbar Interbody Fusion Using O-Arm-Based Navigation in the Novel Oblique Position

PURPOSE

Single-position surgery with patients in a lateral position, which involves inserting percutaneous pedicular screws (PPS) and lateral interbody fusion (LIF) to avoid changing the position, has been reported. The purpose of the present study was to evaluate the utility and appropriateness of single-position LIF-PPS using O-arm-based navigation in the innovative oblique position.

METHODS

This study involved a retrospective analysis of 92 consecutive patients with lumbar spondylolisthesis who underwent LIF-PPS using O-arm-based navigation. Thirty-five subjects demonstrated surgery with repositioning, as well as 24 in the lateral decubitus position, and 33 in the oblique during PPS, where the position was changed to the lateral decubitus position using bed rotation without resetting. We compared these three groups in terms of the surgery time, blood loss, and the accuracy of the screw placement.

RESULTS

The operative time was significantly shorter in the single-position surgery, both in the lateral and oblique positions, compared to surgery in a dual position. The blood loss was significantly increased in the lateral position compared to the dual and oblique positions. The screw trajectory angle on the downside was significantly smaller in the lateral position, and the accuracy of the screw placement on the downside was significantly lower in the lateral position compared to the dual and oblique positions.

CONCLUSION

Single-position surgery could reduce the average surgery time by about 60 min. The present study indicated the oblique position during PPS insertion might make single-position surgery more useful to improve the accuracy of PPS on the downside, with less blood loss.

Robotics and navigation in spine surgery: A narrative review

Introduction

In recent decades, there has been a rising trend of spinal surgical interventional techniques, especially Minimally Invasive Spine Surgery (MIS), to improve the quality of life in an effective and safe manner. However, MIS techniques tend to be difficult to adapt and are associated with an increased risk of radiation exposure. This led to the development of 'computer-assisted surgery' in 1983, which integrated CT images into spinal procedures evolving into the present day robotic-assisted spine surgery. The authors aim to review the development of spine surgeries and provide an overview of the benefits offered. It includes all the comparative studies available to date.

Methods

The manuscript has been prepared as per "SANRA-a scale for the quality assessment of narrative review articles". The authors searched Pubmed, Embase, and Scopus using the terms "(((((Robotics) OR (Navigation)) OR (computer assisted)) OR (3D navigation)) OR (Freehand)) OR (O-Arm)) AND (spine surgery)" and 68 articles were included for analysis excluding review articles, meta-analyses, or systematic literature.

Results

The authors noted that 49 out of 68 studies showed increased precision of pedicle screw insertion, 10 out of 19 studies show decreased radiation exposure, 13 studies noted decreased operative time, 4 out of 8 studies showed reduced hospital stay and significant reduction in rates of infections, neurological deficits, the need for revision surgeries, and rates of radiological ASD, with computer-assisted techniques.

Conclusion

Computer-assisted surgeries have better accuracy of pedicle screw insertion, decreased blood loss and operative time, reduced radiation exposure, improved functional outcomes, and lesser complications.

Augmented Reality Surgical Navigation in Minimally Invasive Spine Surgery: A Preclinical Study

BACKGROUND

In minimally invasive spine surgery (MISS), where the surgeon cannot directly see the patient's internal anatomical structure, the implementation of augmented reality (AR) technology may solve this problem.

METHODS

We combined AR, artificial intelligence, and optical tracking to enhance the augmented reality minimally invasive spine surgery (AR-MISS) system. The system has three functions: AR radiograph superimposition, AR real-time puncture needle tracking, and AR intraoperative navigation. The three functions of the system were evaluated through beagle animal experiments.

RESULTS

The AR radiographs were successfully superimposed on the real intraoperative videos. The anteroposterior (AP) and lateral errors of superimposed AR radiographs were 0.74 ± 0.21 mm and 1.13 ± 0.40 mm, respectively. The puncture needles could be tracked by the AR-MISS system in real time. The AP and lateral errors of the real-time AR needle tracking were 1.26 ± 0.20 mm and 1.22 ± 0.25 mm, respectively. With the help of AR radiographs and AR puncture needles, the puncture procedure could be guided visually by the system in real-time. The anteroposterior and lateral errors of AR-guided puncture were 2.47 ± 0.86 mm and 2.85 ± 1.17 mm, respectively.

CONCLUSIONS

The results indicate that the AR-MISS system is accurate and applicable.

Simultaneous Single-Position Lateral Lumbar Interbody Fusion Surgery and Unilateral Percutaneous Pedicle Screw Fixation for Spondylolisthesis

OBJECTIVE

To evaluate the clinical and radiological efficacy of a combine of lateral single screw-rod and unilateral percutaneous pedicle screw fixation (LSUP) for lateral lumbar interbody fusion (LLIF) in the treatment of spondylolisthesis.

METHODS

Sixty-two consecutive patients with lumbar spondylolisthesis who underwent minimally invasive (MIS)-TLIF with bilateral pedicle screw (BPS) or LLIF-LSUP were retrospectively studied. Segmental lordosis angle (SLA), lumbar lordosis angle (LLA), disc height (DH), slipping percentage, the cross-sectional areas (CSA) of the thecal sac, screw placement accuracy, fusion rate and foraminal height (FH) were used to evaluate radiographic changes postoperatively. Visual analogue scale (VAS) and Oswestry Disability Index (ODI) were used to evaluate the clinical efficacy.

RESULTS

Patients who underwent LLIF-LSUP showed shorter operating time, less length of hospital stay and lower blood loss than MIS-TLIF. No statistical difference was found between the 2 groups in screw placement accuracy, overall complications, VAS, and ODI. Compared with MIS-TLIF-BPS, LLIF-LSUP had a significant improvement in sagittal parameters including DH, FH, LLA, and SLA. The CSA of MIS-TLIF-BPS was significantly increased than that of LLIF-LSUP. The fusion rate of LLIF-LSUP was significantly higher than that of MIS-TLIF-BPS at the follow-up of 3 months postoperatively, but there was no statistical difference between the 2 groups at the follow-up of 6 months, 9 months, and 12 months.

CONCLUSION

The overall clinical outcomes and complications of LLIF-LSUP were comparable to that of MIS-TLIF-BPS in this series. Compared with MIS-TLIF-BPS, LLIF-LSUP for lumbar spondylolisthesis represents a significantly shorter operating time, hospital stay and lower blood loss, and demonstrates better radiological outcomes to maintain lumbar lordosis, and reveal an overwhelming superiority in the early fusion rate.

A Comparison of Outcomes between the Wiltse Approach with Pedicle Screw Fixation and the Percutaneous Pedicle Screw Fixation for Multi-Segmental Thoracolumbar Fractures

OBJECTIVE

Multi-segmental thoracolumbar fracture (MSF) generally refers to fractures occurring in two or more segments of the thoracolumbar spine. With the development of minimally invasive concept, there is little research on its application in the field of MSF. The purpose of this study is to compare two minimally invasive surgical techniques and determine which one is more suitable for treating patients with neurologically intact MSF.

METHODS

We retrospectively analyzed the clinical data of 49 MSF patients with intact nerves who were admitted from January 2017 to February 2019. Among them, 25 cases underwent percutaneous pedicle screw fixation (PPSF), and 24 cases underwent Wiltse approach pedicle screw fixation (WAPSF). The operation time, number of fixed segments, blood loss, length of incision, postoperative ambulation time, accuracy of pedicle screw placement, facet joint violation (FJV), number of C-arm exposures, as well as pre- and postoperative visual analogue scale (VAS), Oswestry disability index (ODI), local Cobb's angle (LCA), and percentage of anterior vertebral body height (PAVBH) were recorded for both groups. Paired sample t-test was used for intra-group comparison before and after surgery while independent sample t-test was used for inter-group comparison.

RESULTS

The differences in the number of fixed segments, intraoperative bleeding, postoperative bed time, accuracy rate of pedicle screw placement, VAS, and ODI between the two groups were not statistically significant (p > 0.05). However, the operative time and total surgical incision length were significantly shorter in the WAPSF group than in the PPSF group (p < 0.05), and the FJV was significantly higher in the PPSF group than in the WAPSF group (p < 0.05). Also, the PPSF group received more intraoperative fluoroscopy (p < 0.05). The result of LCA and PAVBH in the WAPSF group were significantly better than in the PPSF group (p < 0.05).

CONCLUSIONS

Both PPSF and WAPSF were found to be safe and effective in the treatment of MSF without neurological deficits through our study. However, considering radiation exposure, FJV, vertebral height restoration, correction of kyphosis, and learning curve, WAPSF may be a better choice for neurologically intact MSF.

Real-Time Navigation with Guide Template for Pedicle Screw Placement Using an Augmented Reality Head-Mounted Device: A Proof-of-Concept Study

Objective

This study aims to explore the real-time navigation with guide template using an augmented reality head-mounted device (ARHMD) for pedicle screw placement.

Methods

The spatial coordinate relationships between augmented reality images and real objects were established through the custom-made guide template, and the registration and tracking were completed using an ARHMD. The feasibility and accuracy of this method were verified by pedicle screw placement in 2 lumbar models. According to the Gertzbein-Robbins grading scale, the accuracy of pedicle screw placement was assessed. The navigation errors were estimated by measuring the deviation values of entry point and trajectory angle.

Results

A total of 20 pedicle K-wires were placed into L1-L5 in 2 lumbar models, which were successfully completed, with an average time of 11.5 min per model and 69 s per screw. The overall K-wires placement accuracy was 100% (20 screws). The navigation error was 2.77 ± 0.82 mm for the deviation value of entry point, and 3.03° ± 0.94° for the deviation value of trajectory angle.

Conclusions

The application of an ARHMD combined with guide template for pedicle screw placement is a promising navigation approach.

Radiological Assessment of Postoperative Paraspinal Muscle Changes After Lumbar Interbody Fusion With or Without Minimally Invasive Techniques

STUDY DESIGN

Retrospective cohort study.

BACKGROUND

Percutaneous pedicle screws (PPS) have the advantage of being able to better preserve the paraspinal muscles when compared with a traditional open approach. However, the nature of changes in postoperative paraspinal muscle after damage by lumbar fusion surgery has remained largely unknown. It is clinically important to clarify and compare changes in paraspinal muscles after the various surgeries.

OBJECTIVE

(1) To determine postoperative changes of muscle density and cross-sectional area using computed tomography (CT), and (2) to compare paraspinal muscle changes after posterior lumbar interbody fusion (PLIF) with traditional open approaches and minimally invasive lateral lumbar interbody fusions (LLIF) with PPS.

METHODS

We included data from 39 consecutive female patients who underwent open PLIF and 23 consecutive patients who underwent single-staged treatment with LLIF followed by posterior PPS fixation at a single level (L4-5). All patients underwent preoperative, 6 months postoperative, and 1-year postoperative CT imaging. Measurements of the cross-sectional area (CSA) and muscle densities of paraspinal muscles were obtained using regions of interest defined by manual tracing.

RESULTS

We did not find any decrease of CSA in any paraspinal muscles. We did find a decrease of muscle density in the multifidus at 1 year after surgery in patients in the PILF group, but not in those in LLIF/PPS group.

CONCLUSIONS

One year after surgery, a significant postoperative decrease of muscle density of the multifidi was observed only in patients who underwent open PLIF, but not in those who underwent LLIF/PPS.

Percutaneous thoraco-lumbar-sacral pedicle screw placement accuracy results from a multi-center, prospective clinical study using a skin marker-based optical navigation system

STUDY DESIGN

Prospective multi-center study.

OBJECTIVE

The study aimed to evaluate the accuracy of pedicle screw placement using a skin marker-based optical surgical navigation system for minimal invasive thoraco-lumbar-sacral pedicle screw placement.

METHODS

The study was performed in a hybrid Operating Room with a video camera-based navigation system integrated in the imaging hardware. The patient was tracked with non-invasive skin markers while the instrument tracking was via an on-shaft optical marker pattern. The screw placement accuracy assessment was performed by three independent reviewers, using the Gertzbein grading. The screw placement time as well as the staff and patient radiation doses was also measured.

RESULTS

In total, 211 screws in 39 patients were analyzed for screw placement accuracy. Of these 32.7% were in the thoracic region, 59.7% were in the lumbar region, and 7.6% were in the sacral region. An overall accuracy of 98.1% was achieved. No screws were deemed severely misplaced (Gertzbein grading 3). The average time for screw placement was 6 min and 25 secs (± 3 min 33 secs). The average operator radiation dose per subject was 40.3 µSv. The mean patient effective dose (ED) was 11.94 mSv.

CONCLUSION

Skin marker-based ON can be used to achieve very accurate thoracolumbarsacral pedicle screw placements.

Development and validation of an automated planning tool for navigated lumbosacral pedicle screws using a convolutional neural network

BACKGROUND CONTEXT

Navigation and robotic systems have been increasingly applied to spinal instrumentation but dedicated screw planning is a time-consuming prerequisite to tap the full potential of these techniques.

PURPOSE

To develop and validate an automated planning tool for lumbosacral pedicle screw placement using a convolutional neural network (CNN) to facilitate the planning process.

STUDY DESIGN/SETTING

Retrospective analysis and processing of CT and screw planning data randomly selected from a consecutive registry of CT-navigated instrumentations from a single academic institution.

PATIENT SAMPLE

Data from 179 cases was processed for CNN training and validation (155 for training, 24 for validation) leveraging a total of 1182 screws (1052 for training, 130 for validation).

OUTCOME MEASURES

Quantitative and qualitative (Gertzbein-Robbins classification [GR]) validation via comparison of automatically and manually planned reference screws, inter-rater and intra-rater variability.

METHODS

Annotated data from CT-navigated instrumentation was used to train a CNN operating in a vertebra instance-based approach employing a state-of-the-art U-Net framework. Internal five-fold cross-validation and external validation on an independent cohort not previously involved in training was performed. Quantitative validation of automatically planned screws was performed in comparison to corresponding manually planned screws by calculating the minimal absolute difference (MAD) of screw head and tip points, length and diameter, screw direction and Dice coefficient. Results were evaluated in relation to inter-rater and intra-rater variability of manual screw planning.

RESULTS

Automated screw planning was successful in all targeted 130 screws. Compared with manually planned screws as a reference, mean MAD of automatically planned screws was 4.61±2.27 mm for screw head, 3.96±2.19 mm for tip points and 5.51±3.64° for screw direction. These differences were either statistically comparable or significantly smaller when compared with interrater variability of manual screw planning (p>.99 for head point and direction, p=.004 for tip point, respectively). Mean Dice coefficient of 0.61±0.16 indicated significantly greater agreement of automatic screws with the manual reference compared with interrater agreement (Dice 0.56±0.18, p<.001). Automatically planned screws were marginally shorter (MAD 3.4±3.2 mm) and thinner (MAD mean 0.3±0.6 mm) compared with the manual reference, but with statistical significance (p<.0001, respectively). Automatically planned screws were GR grade A in 96.2% in qualitative validation. Planning time was significantly shorter with the automatic approach (0:41 min vs. 6:41 min, p<.0001).

CONCLUSIONS

We derived and validated a fully automated planning tool for lumbosacral pedicle screws using a CNN. Our validation showed noninferiority to manual screw planning and provided sufficient accuracy to facilitate and expedite the screw planning process. These results offer a high potential to improve workflows in spine surgery when integrated into navigation or robotic assistance systems.

Comparison of outcome between percutaneous pedicle screw fixation and the Mini-Open Wiltse Approach with pedicle screw fixation for neurologically intact thoracolumbar fractures: A retrospective study

BACKGROUND

The purpose of this study was to compare the outcome between percutaneous pedicle screw fixation (PPSF) and the mini-open Wiltse approach with pedicle screw fixation (MWPSF) for neurologically intact thoracolumbar fractures.

METHODS

From January 2017 to January 2019, ninety-four patients with neurologically intact thoracolumbar fractures were included in this study. In this retrospective study, forty-nine patients were operated with the PPSF and forty-five patients received MWPSF. The clinical information, surgery-related results and radiographic outcome were collected and compared between the two groups.

RESULTS

There was no significant difference between the two groups in total length of incisions, blood loss, post-operative hospitalization time, visual analog scale (VAS) score and Oswestry disability index (ODI) score. There was also no significant difference in the accuracy rate of pedicle screw placement between two groups; however, the facet joint violation (FJV) was significantly higher in the PPSF group. The atrophic area of multifidus muscle in the PPSF group is significantly larger than that in the MWPSF group and the operative time of MWPSF group was shorter than that in the PPSF group. Meanwhile, the PPSF group obtaining significantly more cumulative exposure to radiation (p < 0.001). The result of vertebral body angle (VBA), Cobb's angle and AVH rate in the MWPSF group were significantly better than those in the PPSF group at the last post-operative follow-up.

CONCLUSIONS

Both minimally invasive treatment techniques (PPSF and MWPSF) are safe and effective in treatment of neurologically intact thoracolumbar fractures. Nevertheless, our results indicate that MWPSF may be a better choice for neurologically intact thoracolumbar fractures, since it protects multifidus muscle, and decreases facet joint violation, operation time, as well as radiation exposure. In addition, MWPSF was associated with better reduction of kyphosis.

Adjacent Segment Degeneration after Short-Segment Lateral Lumbar Interbody Fusion (LLIF)

Purpose

To investigate the influence on the adjacent segment degeneration (ASD) of short-segment lateral lumbar interbody fusion (LLIF) at 2 years postoperatively.

Methods

Ninety-seven consecutive patients who underwent one- or two-level LLIF were included from two institutions. We diagnosed radiographical adjacent segment degeneration with the appearance of adjacent spondylolisthesis (>3 mm) or deterioration of adjacent disk height (>3 mm) on plain radiographs or decrease of the intervertebral angle (>5 degrees). The differences between the two groups with and without radiographical ASD were investigated using univariate and multivariate analyses to determine the risk factors for ASD. The variables included extent of adjacent decompression, posterior fixation method (open method or percutaneous method), and facet violation on postoperative CT.

Results

In total, 19 patients (19.6%) were diagnosed as radiographical ASD 2 years after surgery. Univariate analysis showed that the ASD (+) group had a high frequency of adjacent decompression (21.1 vs. 3.8%, p = 0.035) compared with the ASD (-) group. There were no differences between the two groups in posterior fusion method (percutaneous method 42.1 vs. 57.7%, p = 0.221) or facet joint violation (15.8 vs. 14.1%, p = 0.860). The multivariate analysis found adjacent intervertebral decompression to be a risk factor for ASD 2 years after surgery (odds ratio: 9.95; 95% confidence interval: 1.2–82.1).

Conclusions

Adjacent intervertebral decompression was considered to be a potential risk factor for the development of ASD after spinal fusion with LLIF.

Fluoroscopy-based percutaneous posterior screw placement in the lateral position using the tunnel view technique: technical note

PURPOSE

Lumbar fusion using lateral single position surgery (LSPS) gained popularity during the last few years. While prone percutaneous pedicle screw placement is well described, placing percutaneous pedicle screws with the patient in the lateral position is considered the most complicated part of LSPS. In this article we describe the fluoroscopy navigated technique for lateral percutaneous screw placement using the tunnel view technique.

METHODS

The radiologic background and principles of the tunnel view technique are described. In addition, the special positioning of the patient, the C-arm and the surgical technique is discussed in detail.

RESULTS

This technique is used as the standard for percutaneous screw placement in the prone or lateral positions in our department since 2017. Since the introduction of this technique we have had 0% reoperation rate for symptomatic malpositioned pedicle screws.

CONCLUSION

The tunnel view technique simplifies pedicle screw placement while allowing for permanent observation of pedicle walls and the superior joint surface during placement of the Jamshidi needle. It also allows for confirmation of intrapedicular position of the screw after its implantation. This technique is safe and feasible in our clinical experience.

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.

Comparison of degenerative lumbar spondylolisthesis and isthmic lumbar spondylolisthesis: effect of pedicle screw placement on proximal facet invasion in surgical treatment

BACKGROUND

Pedicle screw invasion of the proximal articular process will cause local articular process degeneration and acceleration, which is an important factor affecting adjacent segment degeneration. Although lumbar spondylolisthesis is a risk factor for screw invasion of the proximal joint, there is no clear conclusion regarding the two different types of spondylolisthesis. Therefore, the purpose of this study was to explore the influence of pedicle screw placement on proximal facet invasion in the treatment of degenerative spondylolisthesis and isthmic spondylolisthesis.

METHODS

In total, 468 cases of lumbar spondylolisthesis treated by decompression and fusion in our hospital from January 2017 to January 2020 were included in this retrospective study. Among them, 238 cases were degenerative spondylolisthesis (group A), and 230 cases were isthmic spondylolisthesis (group B). Sex, age, body mass index, bone mineral density, preoperative visual analog scale (VAS) and Oswestry Disability Index (ODI) scores, postoperative VAS and ODI scores at 1 month and 3 months, and angle of the proximal facet joint at the last follow-up were recorded and compared between the two groups. The degree of pedicle screw invasion of the proximal facet joint was graded and compared by the SEO grading method.

RESULTS

There were no significant differences in sex, age, body mass index, bone mineral density, preoperative VAS and ODI scores, or proximal facet joint angle between the two groups (P > 0.05). There was no significant difference in VAS and ODI scores between the two groups at 1 month and 3 months after the operation (P > 0.05). The VAS score of group A at the last follow-up was 1 (1,2). The VAS score of group B at the last follow-up was 3 (1,3). The ODI score of group A at the last follow-up was 6(4,26). The ODI score of group B at the last follow-up was 15(8,36). The VAS and ODI scores of the two groups at the last follow-up were significantly different (P < 0.05). According to the SEO grading method, the invasion of the proximal articular process by pedicle screw placement in group A involved 320 cases in grade 0, 128 cases in grade I and 28 cases in grade II. In group B, there were 116 cases in grade 0, 248 cases in grade I and 96 cases in grade II, with a significant difference (P < 0.01).

CONCLUSION

In summary, a certain number of cases involving screws invading the proximal facet joint occurred in the two different types of lumbar spondylolisthesis, but the number in the isthmic spondylolisthesis group was significantly higher than that in the degenerative spondylolisthesis group, which caused more trauma to the proximal facet joint and significantly affected the patient prognosis.

Simulation on synthetic bone: A tool for teaching thoracolumbar pedicle screw placement

INTRODUCTION

Simulation workshops for surgical training of residents are becoming popular. The gold standard for teaching thoracolumbar pedicle screw placement are cadaver labs; however, the availability of human bodies is limited. The primary objective of this study was to determine if training on a synthetic bone model improves the apprenticeship of accurate pedicle screw placement. The secondary objective was to check the influence of residents' previous experience in spine surgery.

HYPOTHESIS

The main hypothesis was that theoretical learning with practical application on synthetic bone was superior to theoretical learning alone.

METHODS

Twenty-three orthopedic residents were taught about free-hand pedicle screw placement using a theoretical presentation. Six residents had previous experience with screwing techniques. After randomization in two groups, 11 residents (group 1) participated in a workshop on synthetic bone, whereas 12 residents received only theoretical instruction (group 2). Each resident was asked to place two thoracic screws (T7-T11) and two lumbar screws (L1-L5) on a cadaver. Screw placement accuracy was analyzed using the Gertzbein classification on computed tomography (grades 0 and 1=accurate positioning; grades 2 and 3=malposition>2mm).

RESULTS

Rates of accurate screw positioning were 64.0% and 62.5% for thoracic levels, and 72.7% and 66.6% for lumbar levels in group 1 and 2, respectively. There was no significant difference in malposition rates on cadavers between the groups (p=0.1809). A resident who was first trained by simulation had a chance of decreasing the Gertzbein score with an odds-ratio of 1.7714 [0.7710-4.1515]. The odds ratio was 4.5188 [0.0456-0.8451] when comparing residents with previous experience in spinal surgery to novice residents.

DISCUSSION

Theoretical teaching associated with a simulation model is relevant for learning a surgical technique. A single simulation workshop on synthetic bone seems insufficient to improve pedicle screw placement accuracy compared to theoretical teaching alone. Progressive experience and the repetition of technical gestures during hands-on supervised learning in spine surgery with a senior surgeon had an influence on the accuracy of pedicle screw placement.

LEVEL OF EVIDENCE

II.

Assessment of the outcome of percutaneous pedicle screws in management of degenerative and traumatic dorsal and lumbar pathologies

Background

Percutaneous pedicle screw technique is relatively a recent technique that evolved the concept of posterior spinal instrumentation, utilizing familiar fluoroscopic landmarks to guide the procedure of screws insertion, which despite being technically demanding, it avoids the Musculo-ligamentous damage associated with the conventional posterior technique.

Aim of the work

This study aims to report our experience in managing traumatic and degenerative spine pathologies by the minimally invasive percutaneous technique and assessing its radiological and functional outcome.

Materials and methods

A prospective observational study that included the analysis of the functional, operative, biochemical, and radiological outcomes of 20 patients who underwent uniplanar fluoroscopic-guided dorsal and/or lumbar percutaneous pedicle screw fixation procedures with or without fusion using the sextant, longitude, and Spineart system and any reported complications between January 2018 and December 2019.

Results

The clinical and radiological analysis of 100 percutaneous pedicle screws in degenerative (n:11) and traumatic (n:9) dorsal and/or lumbar cases revealed that the biomechanical stabilizing characteristics are comparable to the conventional posterior approach with the added benefits of the paraspinal muscle-sparing. Satisfactory functional outcome represented in the improvement of the postoperative back pain visual analog score and Oswestry Disability Index Score with acceptable morbidity and complications rate was noticed.

Conclusions

Percutanous pedicle screw fixation is a landmark in the evolution of the minimally invasive spine surgery which can be a safe alternative to the conventional posterior muscle stripping technique with a comparable functional and radiological outcome and good biomechanical profile and an acceptable morbidity rate.

Minimally Invasive Surgery for Spinal Metastasis: A Review

OBJECTIVE

Minimally invasive surgery (MIS) techniques have advanced the treatment of metastatic diseases to the spine. The objective of this review is to describe clinical outcomes, benefits, and complications of these techniques.

METHODS

All relevant clinical studies describing the role of MIS, computer-assisted navigation (CAN), robot-assisted (RA) procedures, and laser interstitial thermal therapy (LITT) in the treatment of metastatic spine diseases were identified from PubMed, MEDLINE, and relevant article bibliographies.

RESULTS

For MIS articles, we filtered 1480 results and identified 26 studies. For CAN, we searched 464 articles to identify 18 articles for review. For RA, we searched 321 results to identify 7 studies for review. For LITT, we identified 21 articles for review.

CONCLUSIONS

MIS for the treatment of spine metastasis has significant potential benefits in reducing surgical site infections, hospital stay, and blood loss without compromising instrument accuracy or overall outcomes. Overall, MIS and its adjuncts have the potential to reduce the risks involved in the treatment of patients with metastatic disease to the spinal column without compromising the benefits of decompression and stabilization of the spine.

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.

Facet Joint Violation by Thoracolumbar Percutaneous Pedicle Screw and Its Effect on Progression of Facet Joint Osteoarthritis

Study Design

A retrospective study.

Purpose

This study aimed to investigate the rate and associated factors of facet violation (FV) in percutaneous pedicle screws (PPS) from the thoracic to the lumbar spine and the effect of FV on facet osteoarthritis (OA) progression.

Overview of Literature

Some reports claim PPS has a higher FV rate than conventional open surgery. However, previous reports of FV in PPS were limited to the lumbar spine; only a few reports included the thoracic spine.

Methods

The present study includes 1,028 PPS inserted from T4 to S1 in 218 patients. The rate of FV and facet OA progression after FV were assessed using computed tomography (CT) scans conducted postoperatively at 1 week and 6 months or more. To identify factors associated with FV or facet OA progression after FV, a multivariate logistic regression analysis was conducted. To investigate whether FV caused facet OA progression, we compared OA progression between patients with FV and matched controls.

Results

FV was observed in 68 (6.6%) of the 1,028 facets, and the thoracic spine was identified as an independent factor associated with FV. OA progression was detected in 48.2% of the cases with FV via CT scans conducted postoperatively at a mean duration of 22.6 months. The time between CT scans was identified as an independent factor for facet OA progression after FV. The rate of OA progression in patients with FV was significantly greater than that of the controls.

Conclusions

FV was observed in 6.6% of the patients, and the thoracic spine was identified as an independent factor associated with FV. OA progression of a violated facet occurs over time. FV is considered a complication leading to facet OA progression.

Surgical Outcomes After Minimally Invasive Direct Lateral Corpectomy with Percutaneous Pedicle Screws for Osteoporotic Thoracolumbar Vertebral Collapse with Neurologic Deficits in the Thoracolumbar Spine Compared with Those After Posterior Spinal Fusion with Vertebroplasty

STUDY DESIGN

Retrospective observational study of a cohort of consecutive patients.

OBJECTIVE

The aim of this study was to compare surgical invasion, mechanical complications, and clinical and radiological outcomes 2 years after surgery between minimally invasive corpectomy following percutaneous pedicle screw placements (X-core/PPS) and posterior fixation with vertebroplasty (VP) for treating osteoporotic vertebral fractures (OVFs), which failed conservative treatment due to neurological deficits.

SUMMARY OF BACKGROUND DATA

Numerous studies have proposed surgical procedures to treat OVFs that fail conservative treatment. However, an optimal approach remains controversial because patients often have numerous comorbid medical complications, frequent instrumentation failure, and/or adjacent vertebral fracture (AVF). Recently, a minimally invasive lateral approach has attracted attention as an alternative procedure to the thoracolumbar junction for corpectomy and expandable cage replacement (X-Core Adjustable VBR System). However, its usefulness and validity is largely unknown.

METHODS

A cohort of 102 consecutive patients with OVF at T11-L1 who underwent surgery were followed up for >2 years after surgery. Ultimately 50 patients were included in the VP group and 45 in the X-core/PPS group. Surgical invasion, radiological examinations, and clinical outcomes between two procedures were compared.

RESULTS

Both X-core/PPS and VP procedures were safe and acceptable for neurological improvement and surgical invasion. The correction loss of local kyphotic angle (LKA) and occurrence of AVF were significantly less in the X-core/PPS group. Oswestry Disability Index in the X-core/PPS group at 2 years after surgery showed better recovery than that in the VP group, and no revision surgery was needed in the X-core/PPS group. Postoperative correction loss of LKA increased significantly when intraoperative endplate injury developed.

CONCLUSION

This next-generation minimally invasive anterior and posterior combined surgery was found to be a safe and useful procedure for OVF treatment to reduce correction loss, mechanical complication, and AVF, resulting in less postoperative low back pain.Level of Evidence: 3.

Factors Affecting Pedicle Screw Insertional Torque in Spine Deformity Surgery

STUDY DESIGN

Retrospective observational study of consecutive patients.

OBJECTIVE

We sought to: (1) clarify the key factors predominantly associated with the insertional torque of pedicle screws; (2) compare the optimal factors for pedicle screw insertion to obtain rigid screw fixation in patients with adult spinal deformity (ASD) and in those with adolescent idiopathic scoliosis (AIS); (3) determine the optimal screw/pedicle ratio (S/P) to obtain rigid pedicle screw fixation.

SUMMARY OF BACKGROUND DATA

Rigid pedicle screw fixation is mandatory to perform corrections for spinal deformities properly and to allow successful fusion after surgery. The fixation depends mainly on screw position accuracy and patient bone quality. Traditionally, spinal surgeons have decided the screw size, trajectory, and tapping size based on their intuition. Insertional torque has been indicated as useful to predict screw fixation strength, and is correlated with screw pullout strength and frequency of postoperative screw loosening.

METHODS

We compared insertion torque at L1-L3 levels of 324 screws in 68 patients with ASD and 58 screws in 32 patients with AIS. We assessed the association between screw/pedicle ratio and insertion torque by constructing a spline curve.

RESULTS

Pedicle and screw diameter correlated positively with insertion torque in patients with either ASD or AIS. The optimal screw/pedicle ratio to obtain rigid pedicle screw fixation in patients with ASD was close to, but less than one, and, by contrast, was about 1 to 1.25 in patients with AIS.

CONCLUSION

We propose the concept of an optimal S/P ratio for obtaining rigid pedicle screw fixation during spinal corrective surgery, which is different for patients with ASD and patients with AIS. The S/P ratio is useful for deciding the appropriate diameter screw for each case in preoperative planning.Level of Evidence: 4.

Minimally Invasive Transforaminal Lumbar Interbody Fusion Using Augmented Reality Surgical Navigation for Percutaneous Pedicle Screw Placement

STUDY DESIGN

This was a retrospective observational study.

OBJECTIVE

The aim of this study was to evaluate the accuracy of percutaneous pedicle screw placement using augmented reality surgical navigation during minimally invasive transforaminal lumbar interbody fusion (TLIF).

SUMMARY OF BACKGROUND DATA

Augmented reality-based navigation is a new type of computer-assisted navigation where video cameras are used instead of infrared cameras to track the operated patients and surgical instruments. This technology has not so far been clinically evaluated for percutaneous pedicle screw placement.

MATERIALS AND METHODS

The study assessed percutaneous pedicle screw placement in 20 consecutive patients who underwent single-level minimally invasive TLIF using augmented reality surgical navigation. Facet joint violation and depression by the inserted pedicle screws were evaluated. Secondary outcome such as radiation dose exposure, fluoroscopy time, and operative time were collected for 3 phases of surgery: preparation phase, pedicle screw placement, and decompression with cage placement.

RESULTS

A clinical accuracy for screw placement within the pedicle (Gertzbein 0 or 1) of 94% was achieved. One screw violated the facet joint with a transarticular pathway. The screw head did not depress the facet in 54%. The use of fluoroscopy during navigation correlated with patient body-mass index (r=0.68, P<0.0001). The pedicle screw placement time corresponded to 36±5% of the total operative time of 117±11 minutes. A statistically significant decrease of 10 minutes in operative time was observed between the first and last 10 procedures which corresponded to the pedicle screw placement time decrease (48±9 vs. 38±7 min, P=0.0142). The learning curve model suggests an ultimate operative time decrease to 97 minutes.

CONCLUSION

Augmented reality surgical navigation can be clinically used to place percutaneous screws during minimally invasive TLIF. However, the lack of tracking of the location of the device requires intraoperative fluoroscopy to monitor screw insertion depth especially in obese patients.

LEVEL OF EVIDENCE

Level III.

Does the use of intraoperative CT scan improve outcomes in Orthopaedic surgery? A systematic review and meta-analysis of 871 cases

BACKGROUND

Intraoperative imaging is frequently made use of in Orthopaedic surgery. Historically, conventional 2-dimensional fluoroscopy has been extensively used for this purpose. However, 2D imaging falls short when it is required to visualise complex anatomical regions such as pelvis, spine, foot and ankle etc. Intraoperative 3D imaging was introduced to counter these limitations, and is increasingly being employed in various sub-specialities of Orthopaedic Surgery.

OBJECTIVES

This review aims to outline the clinical and radiological outcomes of surgeries done under the guidance of intraoperative 3D imaging and compare them to those done under conventional 2D fluoroscopy.

METHODS

Three electronic databases (PubMed, Embase and Scopus) were searched for relevant studies that directly compared intraoperative 3D imaging with conventional fluoroscopy. Case series on intraoperative 3D imaging were also included for qualitative synthesis. The outcomes evaluated included accuracy of implant placement, mean surgical duration and rate of revision surgery due to faulty implants.

RESULTS

A total of 31 studies from sub-specialities of spine surgery, pelvi-acetabular surgery, foot and ankle surgery and trauma surgery, having data on a total of 658 patients were analysed. The study groups which had access to intraoperative 3D imaging was found to have significantly increased accuracy of implant positioning (Odds Ratio 0.35 [0.20, 0.62], p = 0.0002) without statistically significant difference in mean surgical time (p = 0.57). Analysis of the studies that included clinical follow up showed that the use of intraoperative 3D imaging led to a significant decrease in the need for revision surgeries due to faulty implant placement.

CONCLUSION

There is sufficient evidence that the application of intraoperative 3D imaging leads to precise implant positioning and improves the radiological outcome. Further research in the form of prospective studies with long term follow up is required to determine whether this superior radiological outcome translates to better clinical results in the long run.

[Three-dimensional printed drill guide template assisting percutaneous pedicle screw fixation for multiple-level thoracolumbar fractures]

Objective

To evaluate the feasibility and safety of three-dimensional (3D) printed drill guide template-assisted percutaneous pedicle screw fixation for multiple-level thoracolumbar fractures.

Methods

Clinical data of 19 patients with multilevel thoracolumbar fracture without nerve injury who underwent surgical treatment between May 2017 and January 2019 were retrospectively analyzed. There were 9 males and 10 females and their age ranged from 22 to 63 years, with an average age of 43.6 years. Injury cause included traffic accident injury in 12 cases, and fall from height injury in 7 cases. A total of 40 fractured vertebrae were involved in T ₁₀ to L ₃ levels. According to AO classification, there were 29 fractures of type A1, 9 fractures of type A2, and 2 fractures of type A3. According to TANG Sanyuan classification, multiple-segment thoracolumbar fractures were classified as 17 cases of type ⅠA, 1 case of type ⅠB, and 1 case of type ⅡC. The time from injury to operation was 2-6 days, with an average of 3.1 days. The 3D-printed universal drill guide template was used for assisting percutaneous pedicle screw fixation during operation. Intraoperative blood loss, average operation time and fluoroscopy frequency of each screw were recorded. Visual analogue scale (VAS) score was used to evaluate the improvement of low back pain before operation, at 3 days after operation, and at last follow-up. According to the CT at 3 days after operation, the Gertzbein and Robbins scales were used to evaluate the accuracy of screw insertion (the grade A and grade B were regarded as accuracy, the grade A was regarded as excellent of screw insertion). The Cobb angle in sagittal plane of the fracture segment was measured, and the percentage of anterior edge of injured vertebral height was calculated. The consistency of the inclination of bilateral pedicle screws were analyzed postoperatively, and compared the angle of the intraoperative guide plate with the inclination of screw to verify the effectiveness of the guide plate in controlling the inclination.

Results

All the 19 patients completed the operation successfully, and the intraoperative blood loss was 44-67 mL, with an average of 54.3 mL. The average operation time for each screw insertion was 7.3-11.1 minutes, with an average of 9.6 minutes. The average fluoroscopy frequency of each screw insertion was 1.6-2.5 times, with an average of 2.0 times. No spinal cord, nerve root injury, infection, and other complications occurred. All patients were followed up 24-38 months, with an average of 28.7 months. The accuracy of pedicle screws was evaluated by using Gertzbein and Robbins scales: 145 screws were grade A and 11 screws were grade B. The accuracy of screw insertion was 100% and the excellent rate was 92.9%. The CT data at 3 days after operation showed no significant difference in the inclination between the left and right screws in the same vertebral body ( t=0.93, P=0.36). There was no significant difference between the angle of guide plate and the screw inclination ( P>0.05). The VAS score, Cobb angle in sagittal plane, and the percentage of anterior edge of injured vertebral height were significantly improved at 3 days after operation and at last follow-up, and the VAS score was declined at last follow-up compared with 3 days after operation, all showing significant differences ( P<0.05). There was no significant difference in the sagittal Cobb angle and the percentage of anterior edge of injured vertebral height between two postoperative time points ( P>0.05). At last follow-up, no internal fixators were loosened or broken, and all fractures healed well.

Conclusion

For the multiple-level thoracolumbar fractures, 3D-printed drill guide template assisting percutaneous pedicle screw fixation can reduce the operation time, intraoperative blood loss, and fluoroscopy frequency and the screw insertion is accurate and has a good reduction effect.

Radiographs assessment of changes in the psoas muscle at L4-L5 level after single-level lateral lumbar interbody fusion in patients with postoperative motor weakness

The purposes of this study were (1) to investigate postoperative changes in cross-sectional area (CSA) and signal intensity (SI) of the psoas muscle (PS) using magnetic resonance imaging (MRI) and (2) to compare the CSA and SI of the PS between patients with and without motor weakness after single-level lateral lumbar interbody fusion (LLIF) at level L4-L5. Sixty patients were divided into two groups-those with postoperative motor weakness and those without-and the two groups were compared. Baseline demographics and clinical characteristics, such as operation time and blood loss, length of hospital stay, and postoperative complications, were recorded. The CSA and SI of the PS were obtained from the MRI regions of interest defined by manual tracing. Patients who developed motor weakness after surgery were significantly older (p = 0.040). The operation time (p = 0.868), LLIF operative time (p = 0.476), and estimated bleeding loss (p = 0.168) did not differ significantly between groups. In both groups, the CSA and SI of the left and right PS increased after surgery. The change in the CSA of the left PS was significantly higher in patients with weakness (247.6 ± 155.2 mm²) than without weakness (152.2 ± 133.1 mm²) (p = 0.036). The change in SI of the left PS did not differ between the two groups (p = 0.530). To prevent postoperative motor weakness regardless of the operation time, surgeons should be aware of the potential for surgical invasive of the PS during LLIF in older people.

Posterior occipitocervical instrumented fusion for atlantoaxial instability in a 27-month-old child with Down syndrome: illustrative case

BACKGROUND

Upper cervical spine instability is one of the most serious orthopedic problems in patients with Down syndrome. Despite the recent advancement of instrumentation techniques, occipitocervical fusion remains technically challenging in the very young pediatric population with small and fragile osseous elements.

OBSERVATIONS

A 27-month-old boy with Down syndrome was urgently transported to the authors’ hospital because of difficulty in standing and sitting, weakness in the upper limbs, and respiratory distress. Radiographs showed os odontoideum, irreducible atlantoaxial dislocation, and substantial spinal cord compression. Emergency posterior occipitoaxial fixation was performed using O-arm navigation. Improvement in the motor paralysis of the upper left limb was observed from the early postoperative period, but revision surgery was needed 14 days after surgery because of surgical site infection. The patient showed modest but substantial neurological improvement 1 year after the surgery.

LESSONS

There are several clinical implications of the present case. It warns that Down syndrome in the very young pediatric population may lead to rapid progression of spinal cord injury and life crisis. This 27-month-old patient represents the youngest case of atlantoaxial instability in a patient with Down syndrome. O-arm navigation is useful for inserting screws into very thin pedicles.

A Retrospective Analysis of Superior Facet Joint Violation Between Open and Minimally Invasive Transforaminal Lumbar Interbody Fusion and its Relation to Adjacent Segment Disease

STUDY DESIGN

A retrospective study.

OBJECTIVE

The aim was to analyze the superior facet joint violation (SFV) between open transforaminal lumbar interbody fusion (open-TLIF) and minimally invasive transforaminal lumbar interbody fusion (MIS-TLIF) and its effect on the superior and inferior adjacent segment disc height, segmental lordosis, lumbar lordosis, and facet joint degeneration.

SUMMARY OF BACKGROUND DATA

We compared SFV between open-TLIF and MIS-TLIF and its correlation with different factors as well as its effect on adjacent segment disease.

MATERIALS AND METHODS

We retrospectively studied data of patients undergoing single level TLIF surgery from January 2013 to February 2016 in single institutional hospital. Axial and coronal postoperative computed tomography scan images were used to analyze SFV. In secondary analysis patients were divided into nonfacet violation group (NSFVG) and facet violation group (SFVG) and compared the changes on the superior and inferior adjacent level disc height, segmental lordosis, lumbar lordosis, and facet joint degeneration.

RESULTS

Mean SFV grade was significantly greater in MIS-TLIF compared with open-TLIF (odds ratio: 0.638, confidence interval: 0.431-0.944; P=0.025). There was more grade 2 (10.71% vs. 5.60%) and grade 3 (4.46% vs. 1.29%) SFV in MIS-TLIF. Patient with age below 60 and body mass index (BMI) >30 kg/m2 in MIS-TLIF were more prone to high-grade SFV compared with open-TLIF. Further, logistic regression showed patients with BMI ≥30 kg/m2 has 7.137 increased odds of high-grade SFV (95% confidence interval: 3.261-15.618; P=0.000) compared with patients with BMI <30 kg/m2. Compared with NSFVG, SFVG has more SFV (0.096±0.244 vs. 0.177±0.317; P=0.012) and less improvement in lumbar visual analog scale scores -0.65±0.073 versus -0.67±0.074 (P=0.006).

CONCLUSION

MIS-TLIF has more high-grade SFV as well as overall mean SFV in comparison to open-TLIF with BMI >30 kg/m2 and location of pedicle screw as an independent risk factor for SFV and risk of adjacent segment disease increases with SFV.

LEVEL OF STUDY

Level III.

Accuracy of Percutaneous Pedicle Screw Placement after Single-Position versus Dual-Position Insertion for Lateral Interbody Fusion and Pedicle Screw Fixation Using Fluoroscopy

Study Design

Retrospective study.

Purpose

The purpose of this study was to compare the accuracy of percutaneous pedicle screw (PPS) placement between prone and lateral decubitus positions during lateral lumbar interbody fusion (LLIF) and to evaluate the tendency of PPS positioning based on simple computed tomography measurements with patients in the lateral decubitus position.

Overview of Literature

There is insufficient information in the literature regarding the accuracy of inserting a PPS using fluoroscopy in patients in the lateral decubitus position.

Methods

We included 62 patients who underwent combined LLIF surgery and PPS fixation for degenerative lumbar spondylolisthesis with spinal canal stenosis. We compared the patient demographics and the accuracy of fluoroscopy-guided PPS placement between two groups: patients who remained in the lateral decubitus position for the pedicle screw fixation (single-position surgery [SPS] group) and those who were turned to the prone position (dual-position surgery [DPS] group).

Results

There were 40 patients in the DPS group and 22 in the SPS group. Of the 292 PPSs, only 12 were misplaced. In other words, 280/292 screws (95.9%) were placed correctly in the pedicle's cortical shell (grade 0). PPS insertion did not cause neurological, vascular, or visceral injuries in either group. The breach rates for the DPS and SPS groups were 4.1% (grade 1, 5 screws; grade 2, 3 screws; grade 3, 0 screw) and 4.1% (grade 1, 2 screws; grade 2, 2 screws; grade 3, 0 screw), respectively. Although there were no statistically significant differences, the downside PPS had more screw malpositioning than the upside PPS.

Conclusions

We found that PPS insertion with the patient in the decubitus position under fluoroscopic guidance might be as safe and reliable a technique as PPS insertion in the prone position, with a misplacement rate similar to that previously published.

Utility of a Computer-assisted Rod Bending System to Avoid Pull-out and Loosening of Percutaneous Pedicle Screws

STUDY DESIGN

This was a retrospective observational study of a cohort of consecutive patients.

OBJECTIVE

To compare the influence of (1) manual and (2) computer-assisted (CA) rod bending techniques on pedicle screw pull-out resulting in loosening during rod reduction and final tightening.

SUMMARY OF BACKGROUND DATA

Our recent study showed screw pull-out during rod reduction might be a risk factor for loosening of percutaneous pedicle screws (PPSs) postoperatively, resulting in worse postoperative back pain. We retrospectively analyzed data from 53 consecutive patients who underwent minimally invasive lumbar or thoracic spinal stabilization using intraoperative computed tomography image (CT)-guided navigation with conventional manual rod bending or CA rod bending and were followed up for 1 year.

METHOD

Screw pull-out length was measured on axial CT images obtained immediately after screw insertion and postoperatively. Loosening of screws and clinical outcome were evaluated radiographically, clinically, and by CT 1 year after surgery. The frequencies of screw pull-out and screw loosening between the 2 rod bending techniques were compared. Lumbar pain-related factors for both groups of patients were determined preoperatively and 1 year after surgery.

RESULTS

Overall, 360 pedicle screws were placed in the manual group and 124 pedicle screws were placed in the CA group. There was no significant difference in the mean age, sex, bone mineral density, mean stabilized length, or smoking habits of patients between the groups. The diameters, lengths, and trajectory angle (axial and sagittal) of the screws placed were not significantly different between the groups. Screw pull-out rate/length and loosening in the CA group was significantly lower than that in the manual group. Postoperative low back pain improved significantly in the CA group compared with that in the manual group.

CONCLUSION

CA bending is useful to avoid PPS pull-out during rod reduction and screw loosening postoperatively. CA bending is useful to avoid PPS pull-out during rod reduction and screw loosening postoperatively. This result might have been a factor leading to reduced postoperative back pain in the CA group, however, that future studies are need to investigate this association.

3D-printed drill guide template, a promising tool to improve pedicle screw placement accuracy in spinal deformity surgery: A systematic review and meta-analysis

PURPOSE

This study aimed to compare the pedicle screw placement accuracy and surgical outcomes between 3D-printed (3DP) drill guide template technique and freehand technique in spinal deformity surgery.

METHODS

A comprehensive systematic literature search of databases (PubMed, Embase, Cochrane Library, and Web of Science) was conducted. The meta-analysis compared the pedicle screw placement accuracy and other important surgical outcomes between the two techniques.

RESULTS

A total of seven studies were included in the meta-analysis, comprising 87 patients with 1384 pedicle screws placed by 3DP drill guide templates and 88 patients with 1392 pedicle screws placed by freehand technique. The meta-analysis results revealed that the 3DP template technique was significantly more accurate than the freehand technique to place pedicle screws and had a higher rate of excellently placed screws (OR 2.22, P < 0.001) and qualifiedly placed screws (OR 3.66, P < 0.001), and a lower rate of poorly placed screws (OR 0.23, P < 0.001). The mean placement time per screw (WMD-1.99, P < 0.05), total screw placement time (WMD-27.86, P < 0.001), and blood loss (WMD-104.58, P < 0.05) were significantly reduced in the 3DP template group compared with the freehand group. Moreover, there was no significant statistical difference between the two techniques in terms of the operation time and correction rate of main bend curve.

CONCLUSIONS

This study demonstrated that the 3DP drill guide template was a promising tool for assisting the pedicle screw placement in spinal deformity surgery and deserved further promotion.

Uniplanar Cannulated Pedicle Screws in the Correction of Lenke Type 1 Adolescent Idiopathic Scoliosis

OBJECTIVE

To report the clinical use of uniplanar cannulated pedicle screws for the correction of Lenke type 1 adolescent idiopathic scoliosis (AIS), and to evalute its safety and clinical outcomes.

METHODS

A total of 68 patients with Lenke type 1 AIS were retrospective analyzed, among which 38 patients were treated with uniplanar cannulated screws at the concave side of periapical levels and multiaxial screws at the other levels (group A). The remaining 30 patients were treated with all multiaxial screws (group B). The preoperative and postoperative radiographic parameters, axial vertebral rotation, and the safety of the pedicle screws were evaluated.

RESULTS

Preoperative data were comparable between the 2 groups. The postoperative proximal thoracic curve, main thoracic curve, thoracolumbar/lumbar curve, and apical vertebral rotation were significantly improved in both groups (P < 0.05). The coronal correction rates in group A and B were 83% and 81.9% (P = 0.723). The derotation rates in group A and B were 60.8% and 43.2% (P < 0.05). The rotation classification in the group A was also better than group B. The misplacement rate in group A and B was 7.9% and 11.8% (P < 0.05), and the total misplacement rate on the concave side (11.4%) was higher than that of convex side (8.4%). On the concave side, the misplacement rate in group A and B was 9.7% and 12.3%. On the convex side, the misplacement rate in group A and B was 5.9% and 11.1% (P < 0.05).

CONCLUSIONS

Collectively, uniplanar cannulated pedicle screws could effectively increase the accuracy of pedicle screws and facilitate the derotation of the apical vertebra compared with the multiaxial pedicle screws.

A cadaveric precision and accuracy analysis of augmented reality-mediated percutaneous pedicle implant insertion

OBJECTIVE

Augmented reality-mediated spine surgery (ARMSS) is a minimally invasive novel technology that has the potential to increase the efficiency, accuracy, and safety of conventional percutaneous pedicle screw insertion methods. Visual 3D spinal anatomical and 2D navigation images are directly projected onto the operator's retina and superimposed over the surgical field, eliminating field of vision and attention shift to a remote display. The objective of this cadaveric study was to assess the accuracy and precision of percutaneous ARMSS pedicle implant insertion.

METHODS

Instrumentation was placed in 5 cadaveric torsos via ARMSS with the xvision augmented reality head-mounted display (AR-HMD) platform at levels ranging from T5 to S1 for a total of 113 total implants (93 pedicle screws and 20 Jamshidi needles). Postprocedural CT scans were graded by two independent neuroradiologists using the Gertzbein-Robbins scale (grades A-E) for clinical accuracy. Technical precision was calculated using superimposition analysis employing the Medical Image Interaction Toolkit to yield angular trajectory (°) and linear screw tip (mm) deviation from the virtual pedicle screw position compared with the actual pedicle screw position on postprocedural CT imaging.

RESULTS

The overall implant insertion clinical accuracy achieved was 99.1%. Lumbosacral and thoracic clinical accuracies were 100% and 98.2%, respectively. Specifically, among all implants inserted, 112 were noted to be Gertzbein-Robbins grade A or B (99.12%), with only 1 medial Gertzbein-Robbins grade C breach (> 2-mm pedicle breach) in a thoracic pedicle at T9. Precision analysis of the inserted pedicle screws yielded a mean screw tip linear deviation of 1.98 mm (99% CI 1.74-2.22 mm) and a mean angular error of 1.29° (99% CI 1.11°-1.46°) from the projected trajectory. These data compare favorably with data from existing navigation platforms and regulatory precision requirements mandating that linear and angular deviation be less than 3 mm (p < 0.01) and 3° (p < 0.01), respectively.

CONCLUSIONS

Percutaneous ARMSS pedicle implant insertion is a technically feasible, accurate, and highly precise method.

True accuracy of percutaneous pedicle screw placement in thoracic and lumbar spinal fixation with a CT-based navigation system: Intraoperative and postoperative assessment of 763 percutaneous pedicle screws

PURPOSE

To investigate intraoperative reinsertion of percutaneous pedicle screw (PPS) with intraoperative CT-based navigation and to evaluate the rate of deviation of PPS at postoperative radiographic examination.

METHODS

Seven hundred sixty-three screws were inserted in 138 patients. We investigated the rate of occurrence of intraoperative PPS reinsertion after the diagnosis of screw deviation by fluoroscopy and the causes of each screw deviation. The subsequent distribution of PPS deviation was evaluated by postoperative CT. We also assess the difference in variance between the group judged to be PPS misplaced intra-/postoperatively (IOD group/POD group) and appropriate PPS placement (ND group).

RESULTS

Among all the screws inserted, 10 (1.3%) were diagnosed as being deviated by fluoroscopy during surgery, and 74 (9.7%) screws were found to be deviated at postoperative CT evaluation. We found more pedicle screw mismatch in the POD group than in the ND group (52.7 vs 11.0%, P < 0.001). The distance between the screw and the reference was greater in the IOD group than that in the ND group (1.4 ± 1.2 vs 2.4 ± 1.1 vertebral levels, P = 0.016). In one patient in the IOD group, a motor function deficit was observed postoperatively.

CONCLUSION

PPS fixation under intraoperative CT-based navigation did not prevent screw deviation completely. It is necessary to consider errors that occur during surgery and to confirm placement with real-time assistance such as fluoroscopy even in a surgery performed under CT navigation assistance.

Pedicle Screw Insertion: Is O-Arm-Based Navigation Superior to the Conventional Freehand Technique? A Systematic Review and Meta-Analysis

BACKGROUND

Although O-arm-based navigation (ON) has been considered a better choice than the conventional freehand (FH) technique for spine surgery, clinical evidence showing the accuracy of ON compared with the FH technique is limited. The purpose of this study was to evaluate the accuracy of pedicle screw insertion under ON compared with the FH technique.

METHODS

The Cochrane Library, Ovid, Web of Science, PubMed, Embase, and CNKI online databases were searched up to January 2020. Because only a few randomized controlled trials were anticipated, prospective and retrospective comparative studies were also evaluated to compare the accuracy of pedicle screw insertion between ON and FH. Statistical analysis was performed using Stata 16.0. The primary outcomes extracted from articles that met the selection criteria were expressed as odds ratios for dichotomous outcomes with a 95% confidence interval. A χ² test and I² statistics were used to evaluate heterogeneity.

RESULTS

A total of 20 reviews were included in this meta-analysis without identifying additional studies from the references of published articles. These reviews included 1422 patients and 9982 screws. ON was used to insert 4797 pedicle screws and 5185 pedicle screws were inserted using the conventional FH technique with C-arm assistance. The meta-analysis showed that ON is significantly more accurate than FH pedicle screw insertion (odds ratio, 2.46; 95% confidence interval, 1.92-3.16; I² = 43.4%; P = 0.021). I² indicates that the studies have a moderate statistical heterogeneity; subgroup analysis decreased heterogeneity significantly.

CONCLUSIONS

Compared with conventional methods, navigation provides greater accuracy in the placement of pedicle screws, accelerates the insertion, and reduces the complications associated with screw insertion. However, it may increase exposure time to radiation, which may harm the patient's or surgeon's health.

Does Pedicle Screw Fixation Assisted by O-Arm Navigation Perform Better Than Fluoroscopy-guided Technique in Thoracolumbar Fractures in Percutaneous Surgery?: A Retrospective Cohort Study

STUDY DESIGN

A retrospective cohort study.

OBJECTIVE

To evaluate the effect of O-arm navigation in percutaneous surgeries for thoracolumbar fracture in comparison to the use of conventional fluoroscopic technique.

SUMMARY OF BACKGROUND DATA

O-arm navigation is a progressive surgical tool, with extensive research papers reporting its effects. Whereas, there were not many papers describing its accuracy and facet impingement rate when compared with fluoroscopy-guided technique in percutaneous surgeries, especially at varying fracture levels.

MATERIALS AND METHODS

We conducted a retrospective comparative study of 97 consecutive patients of single-level neurological intact thoracolumbar fractures from November 2015 to October 2017 and they were all treated with percutaneous pedicle screw implantation. Screws were classified as 4 grades of perforations and 3 grades of facet joint violation. The association between variables such as anatomic perforation, functional perforation, and facet impingement were investigated by χ test, Fisher exact test or t test. A P-value of <0.05 was considered statistically significant.

RESULTS

A total of 573 pedicle screws were implanted and graded. The overall anatomic perforation rate and functional perforation rate were lower in the O-arm group compared with the fluoroscopy group (8.3% vs. 15.0%, P=0.013, 1.1% vs. 4.2%, P=0.024). At fracture level, the rate of grade 2 perforation of the O-arm group was lower than that of the fluoroscopy group (0% vs. 6.1%, P=0.033). Furthermore, the O-arm group obviously reduced the facet impingement rate both at all levels and at fracture levels (P=0.002; 0.02).

CONCLUSIONS

In percutaneous pedicle screw placement for neurological intact thoracolumbar fracture, the introduction of O-arm navigation improved accuracy, reduced functional perforations, and minimized serious perforations compared with conventional fluoroscopic technique. It also decreased facet joint violation observably and helped to prevent development of adjacent segment degeneration.

Cranial facet joint injuries in percutaneous lumbar pedicle screw placement: a matched-pair analysis comparing intraoperative 3D navigation and conventional fluoroscopy

PURPOSE

The violation of the cranial adjacent facet is a frequent complication in lumbar instrumentations and can induce local pain and adjacent segment disease. Minimally invasive screw implantation is often stated as risk factor in comparison with open approaches. Percutaneous pedicle screw placement (PPSP) can be performed using single X-ray images (fluoroscopy) or intraoperative 3D navigation. The study compares top-level screws in percutaneous lumbar instrumentations regarding facet violations and screw pedicle position using navigation or fluoroscopy.

METHODS

Patients after lumbar PPSP were retrospectively separated according to the intraoperative technique: navigation (NAV) or fluoroscopy (FLUORO). Two blinded investigators graded the top-level screws regarding facet violations and pedicle breach in postoperative CT scans. Subsequent matched cohort analysis was performed for comparable groups.

RESULTS

Evaluating 768 screws, we assessed 70 (9.1%) facet violations. Overall, 186 (24.2%) screws were implanted using navigation. There was no significant difference in the rate of facet violations between both imaging groups (NAV 19/186, 10.2%, FLUORO 51/582, 8.8%, p = 0.55). Totally, 728 (94.8%) of all screws showed a correct pedicle position. Most of the 40 unfavorable pedicle positions were placed by fluoroscopy (NAV 4/186, 2.2%, FLUORO 36/582, 6.6%, p = 0.03). The matched cohorts verified these results (facet violations: NAV 19/186, 10.2%, FLUORO 18/186, 9.7%, p = 0.55; pedicle penetrations: NAV 4/186, 2.2%, FLUORO 12/186, 6.9%, p = 0.04).

CONCLUSIONS

Both intraoperative imaging techniques allow lumbar PPSP with low rates of cranial facet violations if the surgeon intends to preserve facet integrity. Navigation was superior concerning accurate pedicle screw position, but could not significantly prevent facet violations.

Risk Factors Related to Superior Facet Joint Violation During Lumbar Percutaneous Pedicle Screw Placement in Minimally Invasive Transforaminal Lumbar Interbody Fusion (MIS-TLIF)

OBJECTIVE

To investigate the incidence of superior facet joint violation (FJV) during percutaneous pedicle screw placement in minimally invasive transforaminal lumbar interbody fusion, and assess the possible risk factors for FJV.

METHODS

An analysis of 91 patients with lumbar degenerative diseases treated with percutaneous pedicle screw placement via minimally invasive transforaminal lumbar interbody fusion from 2012 to 2018 was performed. Superior FJV was evaluated and graded by 3-dimensional lumbar computed tomography reconstruction. Analysis of possible risk factors included general condition of patients, anatomical characteristics of facet joint (FJ; axial, sagittal, and coronal diameters of FJ, facet angle, lumbar lordosis angle, lumbar lordosis index, and depth of lamina), and surgical factors (pedicle screw angle, screw-superior FJ distance, cranial angle, proximal rod length, and rod contouring).

RESULTS

The overall violation rate of superior FJ was 34.07% (62/182), and high-grade violation rate was 16.06% (27/182). The logistic regression analysis revealed that body mass index ≥30 kg/m² and pedicle screw placement at L5 were independent risk factors of FJV. Anatomical factors showed that the incidence of FJV was significantly increased when axial, sagittal, and coronal diameters of FJ were all ≥12 mm or FA was ≥40°. Surgical factors showed that the FJV group had a smaller pedicle screw angle and screw-superior FJ distance compared with the non-FJV group (P < 0.05).

CONCLUSIONS

Body mass index ≥30 kg/m² and pedicle screw placement at L5 were independent risk factors of superior FJV. FJV was more likely to occur in hypertrophic FJ (axial, sagittal, and coronal diameters ≥12 mm) or coronal orientation (FA ≥40°).

A minimally invasive, 3D-fluoroscopy-navigation-guided, 3D-controlled pedicle approach in spine surgery: first reliable results and impact on patient safety

PURPOSE

Safe pedicle screw placement is a daily challenge to every spine surgeon. Introduction of minimally invasive approaches in spinal surgery led to an impaired facility of inspection of the surgical field increasing the importance of intraoperative imaging and navigation. During the past years, we established a minimally invasive, navigated approach in our clinical setting.

METHODS

We retrospectively reviewed the accuracy of pedicle approaches in patients treated due to traumatic or osteoporotic fractures, spondylitis/discitis, and tumoral lesions. Guide wires for pedicle screws or kyphoplasty cannulas were inserted in a 3D-navigation-guided, minimally invasive technique. Positioning of the guide wires was verified via 3D-scan, and pedicle screws/kyphoplasty cannulas were then visualized via a.p./lateral radiographs. Accuracy data were compared to a standard navigated open approach control group with indications similar to the MIS-group.

RESULTS

23 MIS patients were included in this study (25-84 years, mean 70 years) with a total of 154 placed guide wires. Handling of the navigated Jamshidi needle was easy and secure. The guide wires showed correct placement in 151/154 cases. Three wires (1.9%) needed correction of placement after control scan. There were no vascular or neurologic complications due to wire misplacement. In the open-surgery control group, 7/181 screws (3.9%) needed intraoperative correction presenting no significant difference compared to the correction rate of the MIS-group (p = 0.35).

CONCLUSION

Our study shows the feasibility and reliability of a navigation-guided, minimally invasive pedicle approach in the clinical setting. Therefore, reduced morbidity due to minimized approaches can be combined with higher accuracy of navigated pedicle screw/kyphoplasty cannula placement improving patient safety.

Percutaneous short-segment pedicle instrumentation assisted with O-arm navigation in the treatment of thoracolumbar burst fractures

Object

To compare the clinical and radiological outcomes of O-arm navigation assisted percutaneous pedicle fixation and open freehand pedicle fixation in treatment of AO type A3 thoracolumbar burst fractures (TBFs) without neurological deficit.

Methods

This retrospective study involved 72 patients with type A3 TBFs who underwent O-arm navigation assisted percutaneous pedicle fixation (MIS group) or open freehand posterior pedicle fixation (OPPF group) from September 2015 to December 2017. Demographic data and clinical characteristics were comparable between these two groups before surgery. Operating time, intraoperative blood loss, and the time of hospitalisation stay were analysed. Visual analog scale (VAS) scoring and Oswestry disability index (ODI) was assessed for each patient pre- and postoperatively. Radiographic follow-up was assessed by the Local kyphosis angle (LKA), Vertebral wedge angle (VWA), and Anterior body height (ABH). The accuracy of screw placement was examined by computed tomography.

Results

The two groups were matched in terms of demographic and clinical features. Intraoperative blood loss was significantly less in the MIS group compared to the OPPF group (p < 0.05). The average time for hospitalisation stay in the MIS group was significantly shorter than OPPF group (p < 0.05). However, the operative time revealed no significant difference between two groups (p > 0.05). Meanwhile, the VAS score and ODI score in the MIS group were significantly lower than that in the OPPF group after surgery (p < 0.05). Radiographic assessments revealed no obvious difference between the 2 groups immediately after surgery or at the final follow-up (p > 0.05); The accuracy rate of pedicle screw position in the MIS group was higher than OPPF group (97.8% vs 78.5%, respectively; p < 0.001). No deep wound infection, additional surgery, implant failure, or neurological complications were recorded in either group.

Conclusions

Percutaneous short-segment pedicle instrumentation assisted with O-arm navigation represents an effective and safe alternative for type A3 TBFs. It has several advantages compared with open approach, including less blood loss, shorter hospitalisation, less postoperative pain, higher accuracy of pedicle screw placement, and faster recovery period in treating TBFs. However, it requires a longer learning curve and long-term results have to be studied in other well-designed studies.

The translational potential of this article

Percutaneous short-segment pedicle instrumentation assisted with O-arm navigation represents an effective and safe alternative for type A3 TBFs. The utilization of O-arm navigation and percutaneous pedicle screw fixation guaranteed the high accuracy of screw placement, protected staff from radiation exposure and offered benefits of minimal invasive technique.

Computer Navigation in Minimally Invasive Spine Surgery

PURPOSE OF REVIEW

The goal of the review is to discuss the common general applications of navigation in the context of minimally invasive spine surgery and assess its value in the published literature comparing against non-navigated or navigated techniques.

RECENT FINDINGS

There is increasing utilization of computer navigation in minimally invasive spine surgery. There is synergy between navigation and minimally invasive technologies, such that one enhances or facilitates the other, thus leading to wider applications for both. Specifically, navigation has been shown to improve performance of percutaneous pedicle screw placement, vertebral augmentation, and minimally invasive fusion procedures. Overall, clinical studies have shown better accuracy and less radiation exposure with the use of navigation in spine surgery. The use of navigation in minimally invasive spine surgery enhances the accuracy of instrumentation and decreases radiation exposure. It is yet to be determined whether patient-reported outcomes will differ. Further research on its effect on clinical outcomes may further define the future impact of navigation in minimally invasive spine surgery.

Operative and Perioperative Durations in O-Arm vs C-Arm Fluoroscopy for Lumbar Instrumentation

BACKGROUND

Intraoperative 3-dimensional fluoroscopy (eg, O-arm) has been shown to improve accuracy of pedicle screw placement over 2-dimensional fluoroscopy (C-arm), but its effect on surgery duration remains unclear.

OBJECTIVE

To compare the durations of operative and perioperative times between O-arm and C-arm procedures for degenerative lumbar disorders.

METHODS

We analyzed 198 patients representing 987 pedicle screws treated in a single center by 4 different surgeons between 2013 and 2015. Accuracy of pedicle screw placement was assessed using the Laine classification on postoperative CT scans. Operative and perioperative durations were prospectively reported on the procedure sheet by anesthesiologists.

RESULTS

As expected, placement of pedicle screws using O-arm navigation was overall more accurate compared to C-arm fluoroscopy (strictly intrapedicular screws: 549/663 = 82.8% vs 239/324 = 73.8%, P = .008). This benefit did not depend on surgeon individual performance (P = .17). Average operative duration per instrumented level was significantly shorter in the O-arm group (57.3 min vs 66.1 min, P = .02) but also depended on the surgeon, indication, and interbody fusion. However, only surgeon individual performance remained significantly associated with surgery duration in multivariate analysis (P < .001). Similarly, the only factor that remained significantly associated with longer perioperative durations in multivariate analysis was the indication of surgery (P < .001).

CONCLUSION

This study shows that O-arm navigation does not independently decrease operative duration, nor increases perioperative time, while improving accuracy of pedicle screw placement.

The analysis of percutaneous pedicle screw technique with guide wire-less in lateral decubitus position following extreme lateral interbody fusion

Background

Lateral lumbar interbody fusion (LLIF) and bilateral percutaneous pedicle fixation are valuable, minimally invasive lateral approaches used to treat symptomatic degenerative disc disease. In the current procedure, the patient’s position on the operating table is changed after LLIF surgery from the lateral decubitus to the prone position. The ability to perform both approaches with the patient in the same position should reduce operation time. Use of a guide wire is problematic during percutaneous pedicle screw (PPS) insertion using fluoroscopy with the patient in the lateral decubitus position. A new guide wire-less PPS system may solve this problem and reduce operation time. Here, we evaluated the operative data and efficacy for this technique.

Methods

This study included 30 patients (aged 70.8 ± 8.5 years; 17 men, 13 women) who underwent a combined operation (indirect decompression) using extreme lateral interbody fusion (XLIF) with only a single level for lumbar spinal canal stenosis and lumbar degenerative spondylolisthesis. Patient demographics and operative data were compared between two groups: patients who remained in the lateral decubitus position for pedicle screw fixation (L group) and those turned to the prone position (P group). Radiographic assessment was performed using pre- and postoperative anteroposterior and lateral lumbar films with measurement of lumbar lordosis, segmental lordosis, and segmental translation.

Results

We analyzed 18 patients in the P group and 12 in the L group. Age, sex, height, body weight, body mass index, estimated blood loss, and length of stay did not differ between groups. The operation time was 34 min shorter for the L group (P group 111.9 ± 25.0 vs. L group 77.5 ± 22.2 min, p < 0.01). Pre- and postoperative lordosis, segmental lordosis, and segmental translation did not differ significantly between groups.

Conclusions

A single position after XLIF surgery is a feasible modification to the standard procedure when used with fluoroscopy and a guide wire-less PPS system. The time saved is the main advantage of inserting the PPS with the patient in the lateral decubitus position without repositioning. Use of the lateral PPS with a guide wire-less technique may help improve operative efficiency and reduce cost.

A new method for reducing operation time and radiation exposure in the placement of Jamshidi needles: Technical note

Percutaneous pedicle screws have been used in the treatment of thoracolumbar fractures for decades, and conventional fluoroscopy is commonly used to confirm the positions of the Jamshidi needles during the procedure. In this article, a modified method is reported for the placement of Jamshidi needles. The attending surgeons did not receive any radiation during the procedure and the fluoroscopy time for the patients was little. In our method, all six Jamshidi needles were placed on the pedicles and hammered 2 mm into each entry site. When the verification images were acquired, the medical personnel went behind a lead-lined wall. The positions of the needles were first reviewed and adjusted as needed based on the anterior-posterior (AP) image. Then, the C-arm was rotated and lateral images were obtained to further verify the needle placement. The rest of the screw placement procedure remained the same. The proposed technique was applied in 45 patients with thoracolumbar fractures. It took an average (range) of 5 (4-7) single-shot images to ensure all the needles were positioned at the ideal entry site and 12 (10-17) minutes to complete this step. No neurological symptoms were reported by the patients. Using the proposed technique, the radiation exposure for the surgeons is zero, and the patients are well-protected from excessive radiation exposure. This modified method of embedding all the Jamshidi needles at the entry sites before fluoroscopy is an improved technique compared with the conventional method.

Accuracy in Percutaneous Transpedicular Screws Placement Using Biplane Radioscopy: Systematic Review and Meta-Analysis

STUDY DESIGN

Systematic review and descriptive data meta-analysis.

OBJECTIVE

The objective of this study was to appropriately establish the accuracy in the percutaneous transpedicular screws (PTS) placement using biplane radioscopy (Rx-2D).

SUMMARY OF BACKGROUND DATA

The Rx-2D is a widely-used technique for PTS as it is practical, ubiquitous, and cost-effective. However, the reported "acceptable" accuracy attained by this method is widely variable ranging between 76% and 100%.

METHODS

A systematic review was conducted to screen publications about PTS placement using Rx-2D guidance. PubMed/MEDLINE database was consulted using the search term "percutaneous pedicle screw" from 1977 to 2017. Previous meta-analysis and reference lists of the selected articles were reviewed. Accuracy values were assessed fulfilling the proposed criteria. Observational data meta-analysis was performed. Cochran's Q test was used to determine heterogeneity among data extracted from the series, which was quantified by I test. P-values≤0.05 were considered statistically significant. The results were depicted by Forest plots. Funnel plots were outlined to visualize a possible bias of publication among the selected articles.

RESULTS

In total, 27 articles were included in the analysis. Results of the accuracy were as follow, 91.5% (n=7993; 95% CI, 89.3%-93.6%) of the screws were placed purely intrapedicular, and 96.1% (n=8579; 95% CI, 94.0%-98.2%) when deviation from the pedicle was up to 2 mm.

CONCLUSIONS

This meta-analysis is the largest review of PTS placed with Rx-2D guidance reported up to date. We concluded that the procedure is a safe and reproducible technique. The key values obtained in this work set reliable references for both clinical and training outcome assessing.

Navigation Versus Fluoroscopy in Multilevel MIS Pedicle Screw Insertion: Separate Analysis of Exposure to Radiation of the Surgeon and of the Patients

STUDY DESIGN

This study was a retrospective radiographic analysis of consecutive patients.

OBJECTIVES

To analyze exposure to radiation of the surgeon and-separately-of patients in minimally invasive surgery (MIS) of multilevel posterior stabilization by percutaneous pedicle screw insertion guided by navigation (PIN) versus percutaneous pedicle screw insertion guided by fluoroscopy (PIF).

SUMMARY OF BACKGROUND DATA

Spine surgeons are exposed to a 12-fold higher dose of radiation than other nonspinal musculoskeletal surgeons and PIF in MIS leads to a 2-fold higher dose of radiation than in open surgery. PIN might reduce the dose of radiation for the surgeon and the patient, especially in multilevel MIS surgery. To the best of our knowledge, there are only rare data of short-segment fusions that do not focus on exposure to radiation of surgeons.

METHODS

After power analysis, we included 205 consecutive screws (22 patients). We monitored dose of radiation (recorded separately for patient and surgeon), accuracy of screw placement, time of operation, and approach-related complications.

RESULTS

In PIN, only 58.7% of dose area product (cGy×cm) per screw of PIF was determined for patients (P<0.01). The surgeon was only exposed to 19.9% of radiation per screw in PIN compared with dosage in PIF (P<0.01). Four of 205 screws (2.0%) were classified as being incorrectly positioned: 2 of 87 screws (2.3%) in PIF and 2 of 118 screws (1.7%) in PIN (P>0.05). We did not observe any wound infections.

CONCLUSIONS

PIN in MIS is a safe procedure and does, compared with PIF, lead to significant reduction of radiation dose for patients and-even more-for spine surgeons.