Spinal Navigation during Orthopedic Residency Training: A Double-Edged Sword?

Virtual, Augmented, and Mixed Reality Applications for Surgical Rehearsal, Operative Execution, and Patient Education in Spine Surgery: A Scoping Review

Background and Objectives: Advances in virtual reality (VR), augmented reality (AR), and mixed reality (MR) technologies have resulted in their increased application across many medical specialties. VR's main application has been for teaching and preparatory roles, while AR has been mostly used as a surgical adjunct. The objective of this study is to discuss the various applications and prospects for VR, AR, and MR specifically as they relate to spine surgery. Materials and Methods: A systematic review was conducted to examine the current applications of VR, AR, and MR with a focus on spine surgery. A literature search of two electronic databases (PubMed and Scopus) was conducted in accordance with the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA). The study quality was assessed using the MERSQI score for educational research studies, QUACS for cadaveric studies, and the JBI critical appraisal tools for clinical studies. Results: A total of 228 articles were identified in the primary literature review. Following title/abstract screening and full-text review, 46 articles were included in the review. These articles comprised nine studies performed in artificial models, nine cadaveric studies, four clinical case studies, nineteen clinical case series, one clinical case-control study, and four clinical parallel control studies. Teaching applications utilizing holographic overlays are the most intensively studied aspect of AR/VR; the most simulated surgical procedure is pedicle screw placement. Conclusions: VR provides a reproducible and robust medium for surgical training through surgical simulations and for patient education through various platforms. Existing AR/MR platforms enhance the accuracy and precision of spine surgeries and show promise as a surgical adjunct.

Longitudinal Assessment of Modern Spine Surgery Training: 10-Year Follow-up of a Nationwide Survey of Residency and Spine Fellowship Program Directors

Spine surgeons complete training through residency in orthopaedic surgery (ORTH) or neurosurgery (NSGY). A survey was conducted in 2013 to evaluate spine surgery training. Over the past decade, advances in surgical techniques and the changing dynamics in fellowship training may have affected training and program director (PD) perceptions may have shifted.

Methods

This study is a cross-sectional survey distributed to all PDs of ORTH and NSGY residencies and spine fellowships in the United States. Participants were queried regarding characteristics of their program, ideal characteristics of residency training, and opinions regarding the current training environment. χ2 tests were used to compare answers over the years.

Results

In total, 241 PDs completed the survey. From 2013 to 2023, NSGY increased the proportion of residents with >300 spine cases (86%-100%) while ORTH remained with >90% of residents with < 225 cases (p < 0.05). A greater number of NSGY PDs encouraged spine fellowship even for community spine surgery practice (0% in 2013 vs. 14% in 2023, p < 0.05), which continued to be significantly different from ORTH PDs (∼88% agreed, p > 0.05). 100% of NSGY PDs remained confident in their residents performing spine surgery, whereas ORTH confidence significantly decreased from 43% in 2013 to 25% in 2023 (p < 0.05). For spinal deformity, orthopaedic PDs (92%), NSGY PDs (96%), and fellowship directors (95%), all agreed that a spine fellowship should be pursued (p = 0.99). In both 2013 and 2023, approximately 44% were satisfied with the spine training model in the United States. In 2013, 24% of all PDs believed we should have a dedicated spine residency, which increased to 39% in 2023 (fellowship: 57%, ORTH: 38%, NSGY: 21%) (p < 0.05).

Conclusion

Spine surgery training continues to evolve, yet ORTH and neurological surgery training remains significantly different in case volumes and educational strengths. In both 2013 and 2023, less than 50% of PDs were satisfied with the current spine surgery training model, and a growing minority believe that spine surgery should have its own residency training pathway.

Level of Evidence

IV.

Target registration errors in navigation-assisted mandibular surgery according to the tracking methods and the type of markers: experiments using human dry mandibular bone

OBJECTIVES

This study was conducted to evaluate the accuracy of navigation process according to the type of tracking methods and registration markers. The target registration errors (TREs) were measured at seven anatomical landmarks of the mandible.

METHODS

Four different experiments were performed to obtain the TREs using two tracking methods, the optical tracker (Polaris) and the electromagnetic (EM) tracker (Aurora), and two types of registration markers, invasive and noninvasive markers. All comparisons of TREs were statistically analyzed using SPSS and Python-based statistical package.

RESULTS

The average TRE values obtained from the four experiments were as follows: (1) 0.85 mm (± 0.07) using invasive marker and Aurora, (2) 1.06 mm (± 0.12) using invasive marker and Polaris, (3) 1.43 mm (± 0.15) using noninvasive marker and Aurora, and (4) 1.57 mm (± 0.23) using noninvasive marker and Polaris. Comparisons between all the experimental results revealed statistically significant differences except for the type of tracking system. Although the comparison between the modality of the tracking system showed no significant differences, the EM-based approach consistently demonstrated better performances than the optical type in all comparisons.

CONCLUSIONS

This study demonstrates that irrespective of the tracking modality, using invasive marker is a better choice in terms of accuracy. When using noninvasive marker, it is important to consider the increased TREs. In this study, the noninvasive marker caused a maximum increment of TREs of 0.81 mm compared with the invasive marker. Furthermore, using an EM-based tracker with invasive marker may result in the best accuracy for navigation.

Computed Tomography Intraoperative Navigation in Spinal Surgery: Assessment of Patient Radiation Exposure in Current Practices

BACKGROUND

Patient radiation exposure associated with the use of computed tomography (CT) navigation during spinal surgeries was widely compared with other intraoperative imaging techniques. The aim of this study is to explore the use of navigation with regard to current spinal surgery practices and the technical limitations of such imaging systems.

METHODS

Dosimetric data from 101 patients who underwent intraoperative, CT-navigated spine surgery were retrospectively collected. The study population was divided into 3 groups according to the primary surgical indication. The number of CT image acquisitions per patient, the field length, and the time of exposure per acquisition during a single surgery were compared as well as the radiation dose emitted to patients.

RESULTS

Dose-length products (DLP) per acquisition were 678.52, 656.8, and 649.36 mGy·cm with no significant difference for spinal deformity (SD), degenerative disease (DD), and vertebral fracture (VF) procedures, respectively. Analyzing the number of CT image acquisitions per patient revealed that repeated intraoperative scans were often performed for patients who were suffering from an SD due to technical limitations of the navigation. As a consequence, the cumulative dose was higher in the SD group (DLP total = 1175 mGy·cm) than in the DD (DLP total = 762.74 mGy·cm) and VF (DLP total = 649.36 mGy·cm) groups.

CONCLUSIONS

CT navigation is an efficient intraoperative imaging technique that reduces the rate of surgical complications, but its technical limitations lead to an increased risk of patient radiation exposure, especially for complex surgeries where multiple scanning acquisitions are needed.

CLINICAL RELEVANCE

To avoid patient's overexposure, spine surgeons should minimize the number of intraoperative acquisitions while considering the complexity of the surgery and the limitations of the guidance system. The use of dual guidance systems has also to be considered according to the benefit-risk balance between patient's outcomes and radiation dose exposure.

LEVEL OF EVIDENCE: 4

How accurately can surgeons perform angle manipulation? Quantitative assessment of the accuracy of manual angle manipulation of orthopedic surgery: a cadaver study

INTRODUCTION

To date, only few studies have been performed on the accuracy of manual angle manipulation during orthopedic surgery. This cadaver study was aimed at quantitatively assessing the accuracy of manual angle manipulation performed by orthopedic surgeons according to their surgical experience and comparing it with manipulation performed with the assistance of a digital goniometer.

MATERIALS AND METHODS

Six lower-leg specimens of fresh-frozen human cadavers were subjected to angle manipulation performed via Kirschner wire (K-wire) insertion. K-wires were inserted manually and with the assistance of a digital goniometer at target angles of 0°, 30°, and 60° by three operators who had different levels of experience in orthopedic surgery. The accuracy of the insertion angles at the target angles was evaluated using computed tomography.

RESULTS

The mean angle error in the manual angle manipulation was 8.8° (standard deviation [SD] 6.0). When the target angles were set to 0°, 30°, and 60°, the identified angle errors were 6.1° (SD 4.3), 8.8° (SD 6.6), and 11.7° (SD 5.6), respectively, and each value did not show any significant difference among the operators. With the assistance of a digital goniometer, the mean (SD) angle error was significantly improved to 2.1° (1.1°) (p < 0.001). The amount of improvement in accuracy significantly increased as the target angle increased (p = 0.01).

CONCLUSION

This cadaver study quantified the inaccuracy of manual angle manipulation in orthopedic surgery and showed that these inaccuracies ​​can be improved using an assistive device. These results support the need to develop a device that can compensate manual angle manipulation in orthopedic surgery.

Simulation Training in Spine Surgery

Simulated surgery is part of a growing paradigm shift in surgical education as a whole. Various modalities from cadaver models to virtual reality have been developed and studied within the context of surgical education. Simulation training in spine surgery has an immense potential to improve education and ultimately improve patient safety. This is due to the inherent risk of operating the spine and the technical difficulty of modern techniques. Common procedures in the modern orthopaedic armamentarium, such as pedicle screw placement, can be simulated, and proficiency is rapidly achieved before application in patients. Furthermore, complications such as dural tears can be simulated and effectively managed in a safe environment with simulation. New techniques with steeper learning curves, such as minimally invasive techniques, can now be safely simulated. Hence, augmenting surgical education through simulation has great potential to benefit trainees and practicing orthopaedic surgeons in modern spine surgery techniques. Additional work will aim to improve access to such technologies and integrate them into the current orthopaedic training curriculum.

Use of External Fixators as a 3-Dimensional Navigation Drill Guide for Arthroscopic Ankle Arthrodesis

In this article, we describe a novel technique using external fixators and cannulated screws to construct a 3-dimensional navigation drill guide to predict the screw trajectory before screw insertion that can prevent screw collision during arthroscopic ankle arthrodesis. Four orthopedic residents who had no prior experience of ankle arthrodesis were instructed on how to use the 3-dimensional navigation drill guide and where to insert the screws for ankle arthrodesis. Each resident inserted 6.5 cannulated screws on 8 sawbone ankle models using the device and the C-arm fluoroscopy. An experienced attending surgeon also inserted the same screws on 2 sawbone ankle models to find out if there is any difference between the experienced and inexperienced surgeons. All four residents and an attending surgeon did not experience any collision of screws for the three cannulated screws. Notably, one resident had collision of the 4th screw on his first sawbone model. On the second saw bone model, all surgeons could insert 5 screws without redrilling. A 3-dimensional navigation drill guide constructed with external fixators can assist surgeons in implementing percutaneous screws for arthroscopic ankle arthrodesis.

Accuracy of Thoracolumbar Pedicle Screw Insertion Based on Routine Use of Intraoperative Imaging and Navigation

Study Design

Retrospective review.

Purpose

To determine the accuracy of thoracolumbar pedicle screw insertion with the routine use of three-dimensional (3D) intraoperative imaging and navigation over a large series of screws in an Asian population.

Overview of Literature

The use of 3D intraoperative imaging and navigation in spinal surgery is aimed at improving the accuracy of pedicle screw insertion. This study analyzed 2,240 pedicle screws inserted with the routine use of intraoperative navigation. It is one of very few studies done on an Asian population with a large series of screws.

Methods

Patients who had undergone thoracolumbar pedicle screws insertion using intraoperative imaging and navigation between 2009 and 2017 were retrospectively analyzed. Computed tomography (CT) images acquired after the insertion of pedicle screws were analyzed for breach of the pedicle wall. The pedicle screw breaches were graded according to the Gertzbein classification. The breach rate and revision rate were subsequently calculated.

Results

A total of 2,240 thoracolumbar pedicle screws inserted under the guidance of intraoperative navigation were analyzed, and the accuracy of the insertion was 97.41%. The overall breach rate was 2.59%, the major breach rate was 0.94%, and the intraoperative screw revision rate was 0.7%. There was no incidence of return to the operating theater for revision of screws.

Conclusions

The routine use of 3D navigation and intraoperative CT imaging resulted in consistently accurate pedicle screw placement. This improved the safety of spinal instrumentation and helped in avoiding revision surgery for malpositioned screws.

A Clinical Application Study of Mixed Reality Technology Assisted Lumbar Pedicle Screws Implantation

Background

This was a prospective comparative study of mixed reality (MR) technology assisted lumbar pedicle screws placement and traditional lumbar pedicle screws placement.

Material/Methods

Fifty cases of lumbar pedicle screws placement were randomly divided into 2 groups: 25 cases with MR technology in group A, and 25 cases without MR technology in group B. All patients had their scores on the Oswestry disability index (ODI) of low back pain and the visual analog scale (VAS) of the affected lower limb recorded at pre-operation. Blood loss, operative duration, success rate of first penetration by tap, and number of times C-arm fluoroscopy was performed were recorded at intraoperation. The postoperative drainage was recorded. The ODI of low back pain and VAS of the affected lower limb were recorded at 1, 3, and 6 months after operation.

Results

Group A had less bleeding, shorter operation time, higher success rate of first penetration by tap, and fewer times using C-arm fluoroscopy at intraoperation (P<0.05). There was significant difference in ODI scores and VAS scores at 1 mouth after operation (P<0.05). The postoperative drainage of group A was less than group B (P<0.05). The implantation accuracy of group A was higher than group B (P<0.05). The postoperative recovery rate of low back pain of group A was faster than group B (P<0.05).

Conclusions

The safety of spinal surgery and implantation accuracy of pedicle screw fixation system could be increased by MR technology.

Incidence of pedicle breach following open and minimally invasive spinal instrumentation: A postoperative CT analysis of 513 pedicle screws applied under fluoroscopic guidance

Background

Even though pedicle screw application is a common procedure, and in-spite of spine surgeons being proficient with the technique, mal-positioning of pedicle screws can still occur. We intend to determine by postoperative CT analysis, the incidence of pedicle screw breach in the thoracolumbar spine despite satisfactory intraoperative placement confirmed by fluoroscopy.

Materials and methods

Consecutive patients diagnosed with thoracolumbar fractures who underwent open or minimally invasive posterior stabilization under fluoroscopic guidance were retrospectively reviewed. Postoperative CT scans of patients were analysed to determine the incidence of pedicle breach despite satisfactory intraoperative placement, and also to determine the factors that can predict a breach during intraoperative assessment.

Results

A total of 61 patients with 513 thoracolumbar pedicle screws were available for analysis. Based on our postoperative CT assessment, 28 screws (5.5%; 18 thoracic screws; 10 lumbar screws) had breached the pedicle. There were 14 minor (<3 mm) and 14 major (≥3 mm) breaches. The minimally invasive technique had a significantly lower breach rate compared to open surgery (1.9% vs. 7.9%). By retrospectively analysing the intra-operative fluoroscopic images, we determined certain parameters that could predict a breach during surgery.

Conclusion

Pedicle breaches can still be present despite satisfactory placement of screws visualized intra-operatively. A medial breach is most likely when the length of the pedicle screw spans only up to 50% of the vertebral body as seen on the lateral view but the pedicle screw tip has already transgressed the midline as seen on an AP view. A lateral breach is likely when the tip of the pedicle screw is overlapped by the screw head or is only minimally visualized on an AP view.