Spinal navigation for minimally invasive thoracic and lumbosacral spine fixation: implications for radiation exposure, operative time, and accuracy of pedicle screw placement

Low Radiation Protocol for Intraoperative Robotic C-Arm Can Enhance Adolescent Idiopathic Scoliosis Deformity Correction Accuracy and Safety

STUDY DESIGN

Retrospective case-series study.

OBJECTIVES

To assess (1) low cone beam CT (CBCT) mediated intraoperative navigation to limit radiation exposure without compromising surgical accuracy, and (2) the potential of intraoperative C-arm CBCT navigation to augment pedicle screw (PS) placement accuracy in AIS surgery compared to pre-surgery CT-based planning.

METHODS

The first part involved a prospective phantom study, comparing radiation doses for conventional CT, and standard (6sDCT) and a low dose (5sDCT) Artis Zeego®-imaging. Next, 5sDCT- and 6sDCT-navigation were compared on PS accuracy and radiation exposure during AIS correction. The final part compared surgical AIS deformity correction through intraoperative 5sDCT navigation to a matched cohort treated using conventional pre-surgery CT-scans for navigation. Outcome parameters included operation time, skin dose (SD), dose area product (DAP), intraoperative blood loss, postoperative complications, and PS deviation rates.

RESULTS

The phantom study demonstrated a reduction in radiation for the 5sDCT protocol. Moreover, 5sDCT-imaged patients (n = 15) showed a significantly lower SD (-27.41%) and DAP (-30.92%), without compromising PS accuracy compared with 6sDCT-settings (n = 15). Finally, AIS correction through intraoperative CBCT C-arm navigation (n = 27) significantly reduced screw deviation rates (6.83% versus 10.75%, P = .016) without increasing operation times, compared with conventional CT (n = 37).

CONCLUSIONS

Intraoperative navigation using a CBCT C-arm system improved the accuracy of PS insertion and reduced surgery time. Moreover, it reduced radiation exposure compared with conventional CT, which was further curtailed by adapting the low-dose 5sDCT protocol. In short, our study highlights the benefits of intraoperative CBCT navigation for PS placement in AIS surgery.

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.

Radiation exposure for pedicle screw placement with three different navigation system and imaging combinations in a sawbone model

BACKGROUND

Studies have shown that pedicle screw placement using navigation can potentially reduce radiation exposure of surgical personnel compared to conventional methods. Spinal navigation is based on an interaction of a navigation software and 3D imaging. The 3D image data can be acquired using different imaging modalities such as iCT and CBCT. These imaging modalities vary regarding acquisition technique and field of view. The current literature varies greatly in study design, in form of dose registration, as well as navigation systems and imaging modalities analyzed. Therefore, the aim of this study was a standardized comparison of three navigation and imaging system combinations in an experimental setting in an artificial spine model.

METHODS

In this experimental study dorsal instrumentation of the thoracolumbar spine was performed using three imaging/navigation system combinations. The system combinations applied were the iCT/Curve, cCBCT/Pulse and oCBCT/StealthStation. Referencing scans were obtained with each imaging modality and served as basis for the respective navigation system. In each group 10 artificial spine models received bilateral dorsal instrumentation from T11-S1. 2 referencing and control scans were acquired with the CBCTs, since their field of view could only depict up to five vertebrae in one scan. The field of view of the iCT enabled the depiction of T11-S1 in one scan. After instrumentation the region of interest was scanned again for evaluation of the screw position, therefore only one referencing and one control scan were obtained. Two dose meters were installed in a spine bed ventral of L1 and S1. The dose measurements in each location and in total were analyzed for each system combination. Time demand regarding screw placement was also assessed for all system combinations.

RESULTS

The mean radiation dose in the iCT group measured 1,6 ± 1,1 mGy. In the cCBCT group the mean was 3,6 ± 0,3 mGy and in the oCBCT group 10,3 ± 5,7 mGy were measured. The analysis of variance (ANOVA) showed a significant (p < 0.0001) difference between the three groups. The multiple comparisions by the Kruskall-Wallis test showed no significant difference for the comparison of iCT and cCBCT (p1 = 0,13). Significant differences were found for the direct comparison of iCT and oCBCT (p2 < 0,0001), as well as cCBCT and oCBCT (p3 = 0,02). Statistical analysis showed that significantly (iCT vs. oCBCT p = 0,0434; cCBCT vs. oCBCT p = 0,0083) less time was needed for oCBCT based navigated pedicle screw placement compared to the other system combinations (iCT vs. cCBCT p = 0,871).

CONCLUSION

Under standardized conditions oCBCT navigation demanded twice as much radiation as the cCBCT for the same number of scans, while the radiation exposure measured for the iCT and cCBCT for one scan was comparable. Yet, time effort was significantly less for oCBCT based navigation. However, for transferability into clinical practice additional studies should follow evaluating parameters regarding feasibility and clinical outcome under standardized conditions.

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.

Spine surgery in a state-of-the-art hybrid operating room: an experience of 1745 implanted pedicle screws in the thoracolumbar spine

Hybrid-operating rooms (hybrid-OR) combine high-resolution 2D images and 3D-scans with the possibility of 3D-navigation and allow minimal invasive pedicle screw placement even in the upper thoracic spine. The disadvantage of high cost and increased radiation needs to be compensated with high accuracy and safety. The hybrid operating room consists of a floor-based flat-panel robotic C-arm with 3D-scan capability (Artis Zeego, Siemens; Germany) combined with navigation (BrainLAB Curve, BrainLAB; Germany). Through a minimally invasive incision, a Jamshidi needle was advanced through the pedicle and a K-wire was placed. If 2D image quality did not allow safe placement 3D-navigation was used to place the K-wire. Position was controlled through a 3D-Scan and corrected if necessary before screw placement. Postoperative CTs evaluated screw perforation grade with grade I when completely within the pedicle, II < 2 mm, III 2-4 mm, and IV > 4 mm outside the pedicle. Overall, 354 screws were placed in T1-T6, 746 in the lower thoracic spine T7-T12 and 645 in the L1-L5. Navigation was mainly used in upper thoracic spine cases (31 of 57). In 63 out of 326 cases K-wire was corrected after the 3D-Scan. Overall, 99.1% of the screws showed perforation less than 2 mm. Mean radiation was 13.3 ± 11.7 mSv and significantly higher in the upper thoracic spine and in navigated procedures. Despite higher costs and radiation, the hybrid-OR allows highest accuracy and therefore patient safety in minimal invasive pedicle screw placement in the thoracic and lumbar spine.

Reduction in Radiation Exposure in Minimally Invasive Pedicle Screw Placement Using a Tubular Retractor: A Pilot Study

BACKGROUND AND OBJECTIVES

Percutaneous pedicle screw (PPS) placement is a minimally invasive spinal procedure that has been rapidly adopted over the last decade. However, PPS placement has elicited fear of increased radiation exposure from some surgeons, medical staff, and patients. This is because PPS placement is performed using a K-wire, and the operator must perform K-wire insertion into the pedicle under fluoroscopy. In order to prevent erroneous insertion, there are many occasions when direct insertion is required during radiation exposure, and the amount of radiation exposure to hands and fingers in particular increases. Although these problems are being addressed by navigation systems, these systems are still expensive and not widely available. Attempts have been made to address this situation using instrumentation commonly used in spinal surgery. First, it was considered to visualize anatomical bone markers using a tubular retractor and a microscope. In addition, the use of a self-drilling pin was adopted to locate the pedicle in a narrower field of view. Based on these considerations, a minimally invasive and highly accurate pedicle screw placement technique was developed while avoiding direct radiation exposure. This study evaluated radiation exposure and accuracy of pedicle screw placement using this new procedure in one-level, minimally invasive, transforaminal lumbar interbody fusion (MIS-TLIF).

MATERIALS AND METHODS

Data were collected retrospectively to review pedicle screw placement in single-level MIS TLIFs using a tubular retractor under a microscope. The total fluoroscopy time, radiation dose, and screw placement accuracy were reviewed. Extension of operating time was also evaluated.

RESULTS

Twenty-four patients underwent single-level MIS TLIFs, with placement of 96 pedicle screws. There were 15 females and 9 males, with an average age of 64.8 years and a mean body mass index of 25.5 kg/m². The mean operating time was 201.8 min. The mean fluoroscopic time was 26.8 s. The mean radiation dose of the area dose product was 0.0706 mGy∗m². The mean radiation dose of air kerma was 6.0 mGy. The mean radiation dose of the entrance skin dose was 11.31 mGy. Postoperative computed tomography scans demonstrated 93 pedicle screws confined to the pedicle (97%) and three pedicle screw breaches (3.2%; two lateral, one medial). A patient with screw deviation of the medial pedicle wall developed right-foot numbness necessitating reoperation. There were no complications after reoperation. The average added time with this combined procedure was 39 min (range 16-69 min) per patient.

CONCLUSIONS

This novel pedicle screw insertion technique compares favorably with other reports in terms of radiation exposure reduction and accuracy and is also useful from the viewpoint of avoiding direct radiation exposure to hands and fingers. It is economical because it uses existing spinal surgical instrumentation.

Ergonomics in Spine Surgery

As physician burnout and wellness become increasingly recognized as vital themes for the medical community to address, the topic of chronic work-related conditions in surgeons must be further evaluated. While improving ergonomics and occupational health have been long emphasized in the executive and business worlds, particularly in relation to company morale and productivity, information within the surgical community remains relatively scarce. Chronic peripheral nerve compression syndromes, hand osteoarthritis, cervicalgia and back pain, as well as other repetitive musculoskeletal ailments affect many spinal surgeons. The use of ergonomic training programs, an operating microscope or exoscope, powered instruments for pedicle screw placement, pneumatic Kerrison punches and ultrasonic osteotomes, as well as utilizing multiple surgeons or microbreaks for larger cases comprise several methods by which spinal surgeons can potentially improve workspace health. As such, it is worthwhile exploring these areas to potentially improve operating room ergonomics and overall surgeon longevity.

Unilateral biportal endoscopic lumbar interbody fusion assisted by intraoperative O-arm total navigation for lumbar degenerative disease: A retrospective study

Background

Recently, unilateral biportal endoscopic lumbar interbody fusion (BE-LIF) has been successfully applied for degenerative diseases of the lumbar spine, with good clinical results reported. However, the drawbacks include radiation exposure, limited field of view, and steep learning curves.

Objective

This retrospective study aimed to compare the results between navigation and non-navigation groups and explore the benefits of BE-LIF assisted by intraoperative O-arm total navigation.

Methods

A total of 44 patients were retrospectively analyzed from August 2020 to June 2021. Perioperative data were collected, including operative time, estimated intraoperative blood loss, postoperative drainage, postoperative hospital stay, radiation dose, and duration of radiation exposure. In addition, clinical outcomes were evaluated using postoperative data, such as the Oswestry Disability Index (ODI), visual analog scale (VAS), modified MacNab criteria, Postoperative complications and fusion rate.

Results

The non-navigation and navigation groups included 23 and 21 patients, respectively. All the patients were followed up for at least 12 months. No significant differences were noted in the estimated intraoperative blood loss, postoperative drainage, postoperative hospital stay, fusion rate, or perioperative complications between the two groups. The radiation dose was significantly lower in the navigation group than in the non-navigation group. The average total operation time in the navigation group was lower than that in the non-navigation group (P < 0.01). All clinical outcomes showed improvement at different time points postoperatively, with no significant difference noted between the two groups (P > 0.05).

Conclusions

Compared with the non-navigation approach, O-arm total navigation assistive BE-LIF technology not only has similar clinical results, but also can provide accurate intraoperative guidance and help spinal surgeons achieve accurate decompression. Furthermore, it can reduce radiation exposure to surgeons and operation time, which improve the efficiency and safety of surgery.

Incidence and risk factors associated with superior-segmented facet joint violation during minimal invasive lumbar interbody fusion

BACKGROUND CONTEXT

The trend of minimally invasive lumbar interbody fusion is increasing, and adjacent segmental degeneration (ASD) is one of the complications of the procedures in which facet joint violation (FJV) is a cause. FJVs can occur during percutaneous instrumentation. This study aimed to identify the risk factors that affect FJV during minimally invasive lumbar interbody fusion.

PURPOSE

To identify the risk factors for FJVs and the factors that have a strong impact on the violation.

STUDY DESIGN

Retrospective study.

PATIENT SAMPLE

Patients who underwent minimally invasive lumbar interbody fusion with percutaneous screw fixation between June 2018 and December 2019.

OUTCOME MEASURES

Prevalence of the FJV was reviewed by CT scans which obtained within 6 months after surgery, and the axial, coronal, and sagittal cuts of the scans were evaluated. The FJV was defined as the screw being visible in the facet joint in at least one plane of the CT scan. Radiographic parameters were measured using CT scans including diameters of the facet joints in the axial, coronal, and sagittal planes defined by the facet diameter. The facet angle (FA), the pedicle angle (PA), the screw-facet angle (SFA), the screw-endplate angle (SEA), and the superior margin of the facet joint in the sagittal plane (SD) differed from the head of the screw. At Last, the depth of back muscle was measured in the axial cut of the MRI.

METHODS

This study analyzed 119 patients who underwent minimally invasive lumbar interbody fusion between June 2018 and December 2019. Facet joint violation at the uppermost level was examined using CT in all dimensions. Radiographic parameters (facet diameter, facet angle, pedicle angle, screw-facet angle, screw-endplate angle, and distance between the head of the screws and the facet) were measured. BMI, age, diagnosis, and navigation assistance were included in the study. Risk factors were analyzed to determine which factors had an effect on FJV, and the cut-off was calculated for each parameter.

RESULTS

This study included 119 patients, with a mean age of 63 years. FJV occurred in 13/119 (10.9%) patients and 15/238 (6.3%) joints, respectively. No FJV occurred in 120 joints operated with navigation-assistance and 15/178 (8.4%) joints operated without navigation (p=.01). We found an increasing proportion of violations at more caudal levels: no violations occurred in eight patients with lumbar at L1 or L2, and 1/40 (2.5%), 7/158 (4.4%), and 7/32 (21.9%) of violations occurred at L3, L4, and L5, respectively (p=.01). The diameter of the facet in the axial cut, facet angle, screw facet angle, and distance between the head of the screw and facet were statistically significant in determining the increasing rate of FJV after multivariate analysis was performed (AROC=0.9486, p≤.05). The cutoff point for each radiographic parameter were diameter of facet in the axial ≥17.5 mm, diameter of facet in coronal plane ≥19.5 mm, facet angle ≥41.5^o, screw-facet angle ≥39^o, and distance between facet and the screw ≥-2.6 mm. The estimated probability of FJV was 96.9% when every parameter was greater than the cut-off point.

CONCLUSIONS

An increase in the facet diameter in the axial plane, coronal plane, facet angle, screw facet angle, and the distance between the dome of the screw and facet are risk factors for FJV. Surgeons can avoid violations when radiographic considerations are done. Careful screw placement and good entry points for instrumentation may decrease the rate of facet violation.

First Clinical Experience with a Novel 3D C-Arm-Based System for Navigated Percutaneous Thoracolumbar Pedicle Screw Placement

Background and Objectives: Navigated pedicle screw placement is becoming increasingly popular, as it has been shown to reduce the rate of screw misplacement. We present our intraoperative workflow and initial experience in terms of safety, efficiency, and clinical feasibility with a novel system for a 3D C-arm cone beam computed-tomography-based navigation of thoracolumbar pedicle screws. Materials and Methods: The first 20 consecutive cases of C-arm cone beam computed-tomography-based percutaneous pedicle screw placement using a novel navigation system were included in this study. Procedural data including screw placement time and patient radiation dose were prospectively collected. Final pedicle screw accuracy was assessed using the Gertzbein–Robbins grading system. Results: In total, 156 screws were placed. The screw accuracy was 94.9%. All the pedicle breaches occurred on the lateral pedicle wall, and none caused clinical complications. On average, a time of 2:42 min was required to place a screw. The mean intraoperative patient radiation exposure was 7.46 mSv. Conclusions: In summary, the investigated combination of C-arm CBCT-based navigation proved to be easy to implement and highly reliable. It facilitates the accurate and efficient percutaneous placement of pedicle screws in the thoracolumbar spine. The careful use of intraoperative imaging maintains the intraoperative radiation exposure to the patient at a moderate level.

Comparison of three imaging and navigation systems regarding accuracy of pedicle screw placement in a sawbone model

3D-navigated pedicle screw placement is increasingly performed as the accuracy has been shown to be considerably higher compared to fluoroscopy-guidance. While different imaging and navigation devices can be used, there are few studies comparing these under similar conditions. Thus, the objective of this study was to compare the accuracy of two combinations most used in the literature for spinal navigation and a recently approved combination of imaging device and navigation system. With each combination of imaging system and navigation interface, 160 navigated screws were placed percutaneously in spine levels T11-S1 in ten artificial spine models. 470 screws were included in the final evaluation. Two blinded observers classified screw placement according to the Gertzbein Robbins grading system. Grades A and B were considered acceptable and Grades C-E unacceptable. Weighted kappa was used to calculate reliability between the observers. Mean accuracy was 94.9% (149/157) for iCT/Curve, 97.5% (154/158) for C-arm CBCT/Pulse and 89.0% for CBCT/StealthStation (138/155). The differences between the different combinations were not statistically significant except for the comparison of C-arm CBCT/Pulse and CBCT/StealthStation (p = 0.003). Relevant perforations of the medial pedicle wall were only seen in the CBCT group. Weighted interrater reliability was found to be 0.896 for iCT, 0.424 for C-arm CBCT and 0.709 for CBCT. Under quasi-identical conditions, higher screw accuracy was achieved with the combinations iCT/Curve and C-arm CBCT/Pulse compared with CBCT/StealthStation. However, the exact reasons for the difference in accuracy remain unclear. Weighted interrater reliability for Gertzbein Robbins grading was moderate for C-arm CBCT, substantial for CBCT and almost perfect for iCT.

Minimally Invasive Scoliosis Surgery Is a Feasible Option for Management of Idiopathic Scoliosis and Has Equivalent Outcomes to Open Surgery: A Meta-Analysis

STUDY DESIGN

Meta-analysis.

OBJECTIVE

To compare outcomes between minimally invasive scoliosis surgery (MISS) and traditional posterior instrumentation and fusion in the correction of adolescent idiopathic scoliosis (AIS).

METHODS

A literature search was performed using MEDLINE, PubMed, EMBASE, Google scholar and Cochrane databases, including studies reporting outcomes for both MISS and open correction of AIS. Study details, demographics, and outcomes, including curve correction, estimated blood loss (EBL), operative time, postoperative pain, length of stay (LOS), and complications, were collected and analyzed.

RESULTS

A total of 4 studies met the selection criteria and were included in the analysis, totaling 107 patients (42 MIS and 65 open) with a mean age of 16 years. Overall there was no difference in curve correction between MISS (73.2%) and open (76.7%) cohorts. EBL was significantly lower in the MISS (271 ml) compared to the open (527 ml) group, but operative time was significantly longer (380 min for MISS versus 302 min for open). There were no significant differences between the approaches in pain, LOS, complications, or reoperations.

CONCLUSION

MISS was associated with less blood loss but longer operative times compared to traditional open fusion for AIS. There was no difference in curve correction, postoperative pain, LOS, or complications/reoperations. While MISS has emerged as a feasible option for the surgical management of AIS, further research is warranted to compare these 2 approaches.

Pearls and pitfalls of posterior superior iliac spine reference frame placement for spinal navigation: cadaveric series

BACKGROUND

Navigation and robotics are important tools in the spine surgeon’s armamentarium and use of these tools requires placement of a reference frame. The posterior superior iliac spine (PSIS) is a commonly used site for reference frame placement, due to its location away from the surgical corridor and its ability to provide solid fixation. Placement of a reference frame requires not only familiarity with proper technique, but also command of the relevant anatomy.

OBSERVATIONS

Cadaveric analysis demonstrates a significant difference in PSIS location in males versus females, and additionally provides average thickness for accurate placement.

LESSONS

In this technical note, the authors describe the precise technique for PSIS frame placement in addition to relevant anatomy and offer solutions to commonly encountered problems.

The accuracy and effectiveness of automatic pedicle screw trajectory planning based on computer tomography values: an in vitro osteoporosis model study

Background

Pedicle screw placement in patients with osteoporosis is a serious clinical challenge. The bone mineral density (BMD) of the screw trajectory has been positively correlated with the screw pull-out force, while the computer tomography (CT) value has been linearly correlated with the BMD. The purpose of this study was to establish an in vitro osteoporosis model and verify the accuracy and effectiveness of automated pedicle screw planning software based on CT values in this model.

Methods

Ten vertebrae (L1-L5) of normal adult pigs were randomly divided into decalcification and control groups. In the decalcification group, the vertebral bodies were decalcified with Ethylenediaminetetraacetic acid (EDTA) to construct an in vitro osteoporosis model. In the decalcification group, automatic planning (AP) and conventional manual planning (MP) were used to plan the pedicle screw trajectory on the left and right sides of the pedicle, respectively, and MP was used on both sides of the control group. CT values of trajectories obtained by the two methods were measured and compared. Then, 3D-printed guide plates were designed to assist pedicle screw placement. Finally, the pull-out force of the trajectory obtained by the two methods was measured.

Results

After decalcification, the BMD of the vertebra decreased from − 0.03 ± 1.03 to − 3.03 ± 0.29 (P < 0.05). In the decalcification group, the MP trajectory CT value was 2167.28 ± 65.62 Hu, the AP trajectory CT value was 2723.96 ± 165.83 Hu, and the MP trajectory CT value in the control group was 2242.94 ± 25.80 Hu (P < 0.05). In the decalcified vertebrae, the screw pull-out force of the MP group was 48.6% lower than that of the control group (P < 0.05). The pull-out force of the AP trajectory was 44.7% higher than that of the MP trajectory (P < 0.05) and reached 97.4% of the MP trajectory in the control group (P > 0.05).

Conclusion

Automatic planning of the pedicle screw trajectory based on the CT value can obtain a higher screw pull-out force, which is a valuable new method of pedicle screw placement in osteoporotic vertebre.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12891-022-05101-6.

Time-demand, Radiation Exposure and Outcomes of Minimally Invasive Spine Surgery With the Use of Skin-Anchored Intraoperative Navigation: The Effect of the Learning Curve

STUDY DESIGN

Retrospective review.

OBJECTIVE

The aim was to evaluate the learning curve of skin-anchored intraoperative navigation (ION) for minimally invasive lumbar surgery.

SUMMARY OF BACKGROUND DATA

ION is increasingly being utilized to provide better visualization, improve accuracy, and enable less invasive procedures. The use of noninvasive skin-anchored trackers for navigation is a novel technique, with the few reports on this technique demonstrating safety, feasibility, and significant reductions in radiation exposure compared with conventional fluoroscopy. However, a commonly cited deterrent to wider adoption is the learning curve.

METHODS

Retrospective review of patients undergoing 1-level minimally invasive lumbar surgery was performed. Outcomes were: (1) time for ION set-up and image-acquisition; (2) operative time; (3) fluoroscopy time; (4) radiation dose; (5) operative complications; (6) need for repeat spin; (7) incorrect localization.Chronologic case number was plotted against each outcome. Derivative of the nonlinear curve fit to the dataset for each outcome was solved to find plateau in learning.

RESULTS

A total of 270 patients [114 microdiscectomy; 79 laminectomy; 77 minimally invasive transforaminal lumbar interbody fusion (MI-TLIF)] were included. (1) ION set-up and image-acquisition: no learning curve for microdiscectomy. Proficiency at 23 and 31 cases for laminectomy and MI-TLIF, respectively. (2) Operative time: no learning curve for microdiscectomy. Proficiency at 36 and 31 cases for laminectomy and MI-TLIF, respectively. (3) Fluoroscopy time: no learning curve. (4) Radiation dose: proficiency at 42 and 33 cases for microdiscectomy and laminectomy, respectively. No learning curve for MI-TLIF. (5) Operative complications: unable to evaluate for microdiscectomy and MI-TLIF. Proficiency at 29 cases for laminectomy. (6) Repeat spin: unable to evaluate for microdiscectomy and laminectomy. For MI-TLIF, chronology was not associated with repeat spins. (7) Incorrect localization: none.

CONCLUSIONS

Skin-anchored ION did not result in any wrong level surgeries. Learning curve for other parameters varied by surgery type, but was achieved at 25-35 cases for a majority of outcomes.

LEVEL OF EVIDENCE

Level III.

Technique, Time Demand, Radiation Exposure, and Outcomes of Skin-anchored Intraoperative 3D Navigation in Minimally Invasive Posterior Cervical Laminoforaminotomy

STUDY DESIGN

This was a retrospective review.

OBJECTIVE

The objective of this study was to describe our technique and evaluate the time demand, radiation exposure, and outcomes of minimally invasive posterior cervical laminoforaminotomy (MI-PCLF) using skin-anchored intraoperative navigation (ION).

BACKGROUND

Although bone-anchored trackers are most commonly used for ION, a novel technique utilizing noninvasive skin-anchored trackers has recently been described for lumbar surgery and has shown favorable results. There are currently no reports on the use of this technology for cervical surgery.

METHODS

Time demand, radiation exposure, and perioperative outcomes of MI-PCLF using skin-anchored ION were evaluated.

RESULTS

Twenty-one patients with 36 operative levels were included. Time for ION setup and operative time were a median of 34 and 62 minutes, respectively. Median radiation to the patient was 2.5 mGy from 10 seconds of fluoroscopy time. Radiation exposure to operating room personnel was negligible because they are behind a protective lead shield during ION image acquisition. There were no intraoperative complications or wrong-level surgeries. One patient required a repeat ION spin, and in 2 patients, ION was abandoned and standard fluoroscopy was used.

CONCLUSIONS

Skin-anchored ION for MI-PCLF is feasible, safe, and accurate. It results in short operative times, minimal complications, low radiation to the patient, and negligible radiation to operating room personnel.

Vertebrae segmentation in reduced radiation CT imaging for augmented reality applications

PURPOSE

There is growing evidence for the use of augmented reality (AR) navigation in spinal surgery to increase surgical accuracy and improve clinical outcomes. Recent research has employed AR techniques to create accurate auto-segmentations, the basis of patient registration, using reduced radiation dose intraoperative computed tomography images. In this study, we aimed to determine if spinal surgery AR applications can employ reduced radiation dose preoperative computed tomography (pCT) images.

METHODS

We methodically decreased the imaging dose, with the addition of Gaussian noise, that was introduced into pCT images to determine the image quality threshold that was required for auto-segmentation. The Gaussian distribution's standard deviation determined noise level, such that a scalar multiplier (L: [0.00, 0.45], with steps of 0.03) simulated lower doses as L increased. We then enhanced the images with denoising algorithms to evaluate the effect on the segmentation.

RESULTS

The pCT radiation dose was decreased to below the current lowest clinical threshold and the resulting images produced segmentations that were appropriate for input into AR applications. This held true at simulated dose L = 0.06 (estimated 144 mAs) but not at L = 0.09 (estimated 136 mAs). The application of denoising algorithms to the images resulted in increased artifacts and decreased bone density.

CONCLUSIONS

The pCT image quality that is required for AR auto-segmentation is lower than that which is currently employed in spinal surgery. We recommend a reduced radiation dose protocol of approximately 140 mAs. This has the potential to reduce the radiation experienced by patients in comparison to procedures without AR support. Future research is required to identify the specific, clinically relevant radiation dose thresholds required for surgical navigation.

Intraoperative Navigation in Spine Surgery: Effects On Complications and Reoperations

INTRODUCTION

Intraoperative navigation during spine surgery improves pedicle screw placement accuracy. However, limited studies have correlated navigation with clinical factors including operative time and safety. This study compares complications and reoperations between surgeries with and without navigation.

METHODS

Posterior cervical and lumbar fusions and deformity surgeries from 2011-2018 were queried from the NSQIP database and divided by navigation use. Patients aged >89, deformity patients aged <25, and patients undergoing surgery for tumors, fractures, infections, or non-elective indications were excluded. Demographics and perioperative factors were compared with univariate analysis. Outcomes were compared with multivariable logistic regression adjusting for age, sex, BMI, ASA class, surgical region, and multiple levels. Outcomes were also compared stratifying by revision status.

RESULTS

Navigated surgery patients had higher ASA status (p<0.0001), more multiple-level surgeries (p<0.0001), and longer operations (p<0.0001). Adjusted analysis revealed navigated lumbar surgeries had lower odds of complications (OR=0.82, 95%CI=0.77-0.90, p<0.0001), blood transfusion (OR=0.79, 95%CI=0.72-0.87, p<0.0001), and wound debridement/drainage (OR=0.66, 95%CI=0.44-0.97, p=0.04) compared to non-navigated procedures. Navigated cervical fusions had increased odds of transfusion (OR=1.53, 95%CI=1.06-2.23, p=0.02). Navigated primary fusions had decreased odds of complications (OR=0.91, 95%CI=0.85-0.98, p=0.01); no difference was found in revisions (OR=0.89, 95%CI=0.69-1.14, p=0.34).

CONCLUSIONS

Navigated surgery patients experienced longer operations due to a combination of time using navigation, more multi-level procedures and larger comorbidity burden, without differences in infections. There were fewer complications and wound washouts in navigated lumbar surgeries due to a higher percentage of minimally invasive cases. Co-utilization of navigation and minimally invasive surgery may benefit properly indicated patients.

Lateral mass screw placement in the atlas: description of a novel surgical technique, radiographic parameters, and review of the literature

Background

Numerous techniques of C1 lateral mass screw placement have been described. We sought to delineate the radiographic angle of safety medially and laterally and describe a novel surgical technique of C1 lateral mass screw placement. We sought to (I) determine the angle of safety medially and laterally of the C1 lateral mass; (II) assess the size available of the lateral mass in the AP and coronal planes; (III) describe novel technique of insertion of a C1 lateral mass screw utilizing navigation and a novel start point.

Methods

We retrospectively reviewed cervical computed tomography (CT) images of normal adults. Radiographic measurements were then obtained using these images including the angle (degrees) of safety medially and lateral of the C1 lateral mass bilaterally, as well as the length and width (mm) of the C1 lateral masses. A novel surgical technique was used by identifying the confluence of the medial aspect of the posterior arch and the lateral mass. This confluence is then marked out as the C1 screw start point. Under navigation guidance, lateral mass screws were placed with 0 degrees of medial-lateral angulation from posterior to anterior.

Results

Forty-five patients with a mean age of 52.6±25.6 years (33% female) were included. The mean medial and lateral angle of safety of the C1 lateral mass bilaterally was 23±3.8 degrees and 32±5 degrees, respectively. Average length and width of the lateral mass was 17.7 and 13.3 mm respectively.

Conclusions

This study describes the radiographic window of safety medially and laterally for safe and reproducible placement of C1 lateral mass screws. Further, a novel technique using a medial start point and navigation guidance with 0 degrees of angulation in the coronal plane is described. Further research is required to assess outcomes of patients utilizing this method as well as biomechanical studies to assess this construct strength compared to others that are frequently used.

Does intraoperative 3D navigation improve SpineJack vertebral augmentation in thoracic and lumbar compression fracture?

INTRODUCTION

The aim of this retrospective study was to evaluate the effect of navigation on the positioning of the SpineJack implant in the treatment of thoracic and lumbar compression fractures.

METHODS

Between January 2018 and December 2019, all patients operated on for thoracic or lumbar fracture using the SpineJack device in stand-alone were included in this single-center study. The positioning of the SpineJack implant was analyzed on axial CT views by measuring the angle between the axis of the pedicle and the axis of the final implant. The relationships between implant positioning and the use of navigation or fluoroscopy, pedicle dimensions and levels of injury were analyzed. Surgical time, radiation exposure, radiological findings and complications were assessed.

RESULTS

One hundred patients were included, for 103 fractured vertebrae and a total of 205 implants, 148 placed under standard fluoroscopy and 57 with the Surgivisio navigation system. For pedicle diameters≥5mm (165 implants), the positioning of the implant relative to the axis of the pedicle was significantly better in the navigation group: 2°±1.4° (range, 0-7°) in the fluoroscopy group versus 1.2°±1.1° (range, 0-5°) in the navigation group (p=0.04). There were no significant differences in reduction of vertebral kyphosis angle or mean operating time. Dose area product (DAP) was significantly higher with navigation: 4.43Gy.cm² versus 0.47Gy.cm² (p<0.001) and dose to the surgeon significantly lower: 0.5 versus 1.6μSv (p<0.001). No difference was found regarding complications. Subgroup analysis showed significantly greater operative time and patient irradiation in the fluoroscopy group when pedicle diameter was less than 5mm.

CONCLUSION

This study demonstrates the interest of navigation for positioning the SpineJack implant with respect to the pedicle axis in vertebrae with pedicle diameter≥5mm. This study also confirmed the reliability of navigation and lower radiation dose to the surgeon, regardless of the fracture level. Navigation reduced operating time and patient irradiation for vertebrae with pedicle diameter<5mm.

LEVEL OF EVIDENCE

IV; retrospective study.

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.

The Clinical Impact of Image Guidance and Robotics in Spinal Surgery: A Review of Safety, Accuracy, Efficiency, and Complication Reduction

Image guidance (IG) and robotic-assisted (RA) surgery are modern technological advancements that have provided novel ways to perform precise and accurate spinal surgery. These innovations supply real-time, three-dimensional imaging information to aid in instrumentation, decompression, and implant placement. Although nothing can replace the knowledge and expertise of an experienced spine surgeon, these platforms do have the potential to supplement the individual surgeon's capabilities. Specific advantages include more precise pedicle screw placement, minimally invasive surgery with less reliance on intraoperative fluoroscopy, and lower radiation exposure to the surgeon and staff. As these technologies have become more widely adopted over the years, novel uses such as tumor resection have been explored. Disadvantages include the cost of implementing IG and robotics platforms, the initial learning curve for both the surgeon and the staff, and increased patient radiation exposure in scoliosis surgery. Also, given the relatively recent transition of many procedures from inpatient settings to ambulatory surgery centers, access to current devices may be cost prohibitive and not as readily available at some centers. Regarding patient-related outcomes, much further research is warranted. The short-term benefits of minimally invasive surgery often bolster the perioperative and early postoperative outcomes in many retrospective studies on IG and RA surgery. Randomized controlled trials limiting such confounding factors are warranted to definitively show potential independent improvements in patient-related outcomes specifically attributable to IG and RA alone. Nonetheless, irrespective of these current unknowns, it is clear that these technologies have changed the field and the practice of spine surgery. Surgeons should be familiar with the potential benefits and tradeoffs of these platforms when considering adopting IG and robotics in their practices.

Clinical Accuracy, Technical Precision, and Workflow of the First in Human Use of an Augmented-Reality Head-Mounted Display Stereotactic Navigation System for Spine Surgery

BACKGROUND

Augmented reality mediated spine surgery is a novel technology for spine navigation. Benchmark cadaveric data have demonstrated high accuracy and precision leading to recent regulatory approval. Absence of respiratory motion in cadaveric studies may positively bias precision and accuracy results and analogous investigations are prudent in live clinical scenarios.

OBJECTIVE

To report a technical note, accuracy, precision analysis of the first in-human deployment of this technology.

METHODS

A 78-yr-old female underwent an L4-S1 decompression, pedicle screw, and rod fixation for degenerative spine disease. Six pedicle screws were inserted via AR-HMD (xvision; Augmedics, Chicago, Illinois) navigation. Intraoperative computed tomography was used for navigation registration as well as implant accuracy and precision assessment. Clinical accuracy was graded per the Gertzbein-Robbins (GS) scale by an independent neuroradiologist. Technical precision was analyzed by comparing 3-dimensional (3D) (x, y, z) virtual implant vs real implant position coordinates and reported as linear (mm) and angular (°) deviation. Present data were compared to benchmark cadaveric data.

RESULTS

Clinical accuracy (per the GS grading scale) was 100%. Technical precision analysis yielded a mean linear deviation of 2.07 mm (95% CI: 1.62-2.52 mm) and angular deviation of 2.41° (95% CI: 1.57-3.25°). In comparison to prior cadaveric data (99.1%, 2.03 ± 0.99 mm, 1.41 ± 0.61°; GS accuracy 3D linear and angular deviation, respectively), the present results were not significantly different (P > .05).

CONCLUSION

The first in human deployment of the single Food and Drug Administration approved AR-HMD stereotactic spine navigation platform demonstrated clinical accuracy and technical precision of inserted hardware comparable to previously acquired cadaveric studies.

Comparison of the Wiltse Approach and Percutaneous Pedicle Screw Fixation Under O-arm Navigation for the Treatment of Thoracolumbar Fractures

Objectives

The aim of this study was to evaluate the clinical outcomes of the Wiltse approach and percutaneous pedicle screw placement under O‐arm navigation for the treatment of thoracolumbar fracture.

Methods

We enrolled a total of 54 patients with neurologically intact thoracolumbar fracture who received minimally invasive treatments between October 2014 and October 2018 in this retrospective study. Among these, 28 patients (22 males and six females, with a mean age of 48.6 ± 9.6 years) were treated with pedicle screw fixation through the Wiltse approach (WPSF), and another 26 (15 males and 11 females, with a mean age of 45.7 ± 10.6 years) received percutaneous pedicle screw fixation under O‐arm navigation (OPSF). Statistical methods were used to perform a detailed comparison of clinical outcomes, radiologic findings, and complications between the two groups obtained preoperatively, postoperatively, and at last follow‐up.

Results

All patients underwent surgery successfully and finished a follow‐up of more than 12 months. No serious complications, such as infection, blood vessel injury, or spinal cord or nerve root injury occurred. Visual analog scale (VAS) scores, Oswestry disability index (ODI) scores, local Cobb angle (LCA), vertebral wedge angle (VWA), and R value were notably improved after surgery, though there was no clear discrepancy between the groups at each time point (P > 0.05). During the follow‐up period, no patients developed neurological impairment or implant‐related complications, and no patients underwent revision surgery. The WPSF group had a significantly shorter operation time than the OPSF group (68.1 ± 9.8 vs 76.1 ± 9.0 minutes, P = 0.005). Moreover, the WPSF group showed less cost of surgery than the WPSF group (48142.1 ± 1430.1 vs 59035.4 ± 1152.7 CNY, P < 0.001). There were no significant differences between the two groups in terms of the intraoperative bleeding, length of incision, or postoperative hospitalization time (P > 0.05). The accuracy of pedicle screw placement was 95.2% (160/168) in the WPSF group and 96.8% (151/156) in the OPSF group, with no significant difference between the groups (P = 0.432).

Conclusion

Both WPSF and OPSF were safe and effective for the treatment of thoracolumbar fracture. Although the two groups showed favorable clinical and radiologic outcomes through to final follow‐up, we recommended the minimally invasive WPSF given its shorter operation time and lower cost of surgery.

Use of Intraoperative CT Improves Accuracy of Spinal Navigation During Screw Fixation in Cervico-thoracic Region

STUDY DESIGN

A retrospective analysis of a single-center consecutive series of patients.

OBJECTIVE

To test the hypothesis that using a mobile intraoperative computed tomography in combination with spinal navigation would result in better accuracy of lateral mass and pedicle screws between C3 and T5 levels, compared to cone-beam computed tomography and traditional 2D fluoroscopy.

SUMMARY OF BACKGROUND DATA

Use of spinal navigation associated with 3D imaging has been shown to improve accuracy of screw positioning in the cervico-thoracic region. However, use of iCT imaging compared to a cone-beam CT has not been fully investigated in these types of surgical interventions.

METHODS

We retrospectively analyzed a series of patients who underwent posterior cervico-thoracic fixations using different intraoperative imaging systems in a single hospital. We identified three different groups of patients: Group A, operated under 2D-fluoroscopic guidance without navigation; Group B: O-arm guidance with navigation; Group C: iCT AIRO guidance with navigation. Primary outcome was the rate of accurately placed screws, measured on intra or postoperative CT scan with Neo et al. classification for cervical pedicles screws and Gertzbein et al. for thoracic pedicle screws. Screws in cervical lateral masses were evaluated according to a new classification created by the authors.

RESULTS

Data on 67 patients and 495 screws were available. Overall screw accuracy was 92.8% (95.6% for lateral mass screws, 81.6% for cervical pedicle screws, and 90% for thoracic pedicle screws). Patients operated with iCT AIRO navigation had significantly fewer misplaced screws (2.4%) compared to 2D-fluoroscopic guidance (9.1%) and O-arm navigation (9.7%) (P = 0.0152). Accuracy rate of iCT navigation versus O-arm navigation was significantly higher (P = 0.0042), and there was no statistically significant difference in surgical time between the three Groups (P = 0.5390).

CONCLUSION

Use of high-quality CT associated with spinal navigation significantly improved accuracy of screw positioning in the cervico-thoracic region.Level of Evidence: 3.

Minimally Invasive Cochlear Implantation Assisted by Intraoperative CT Scan Combined to Neuronavigation

OBJECTIVE

The objective of this work was to study the feasibility of minimally invasive cochlear implantation under intraoperative computerized tomography-scan coupled to navigation.

MATERIALS AND METHODS

Five human resin temporal bones (two adults and three children) were used. Initially, a temporal bone imaging was obtained by the intraoperative CT-scan coupled to the navigation (O-ARM). The navigation-assisted drilling began at the mastoid surface creating a conical tunnel (4-2 mm in diameter) through the facial recess and down to the round window. A cochleostomy was performed based on the navigation. A sham electrode array was inserted in the drilled tunnel and into the cochlea.Postoperative CT-scan and dissection were performed to evaluate the trajectory, and possible injury to the external auditory canal, ossicles, or facial nerve.

RESULTS

The mean duration of the procedure was 24.4 ± 3.79 minutes (range, 15-35). Cochleostomy was possible in all cases without injury to other structures. The sham array was inside the cochlea in all cases. The mean distance between the drilled canal and the mastoid portion of the facial nerve was 1.2 ± 0.07 mm (range, 1.08-1.38). The mean tracking error was 0.6 ± 0.26 mm (range, 0.20-0.72) at the entry point, 0.6 ± 0.33 mm (range, 0.2-1.02) at the facial nerve and 0.4 ± 0.07 mm (range, 0.36-0.51) at the cochleostomy.

CONCLUSION

Cochlear implantation through a minimally invasive approach assisted by intraoperative imaging combined with navigation was feasible in operating room environment and experimental conditions.

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.

Transfacet screws using spinal navigation in addition to anterior or oblique lumbar interbody fusion: technical note and preliminary results

Transfacet screws (TFS) are an alternative to the classic bilateral pedicular screws (BPS) in addition to anterior (ALIF) or oblique (OLIF) lumbar interbody fusion. Spinal navigation could help the surgeon in technically demanding procedures in order to avoid screw malposition. Although spinal navigation is commonly used in BPS, its contribution in TFS remains unclear. Our aim here was to assess the feasibility of TFS using spinal navigation in addition to anterior lumbar fusion. Five patients suffering from lumbar degenerative disc disease were included. During the same general anaesthesia, we performed successively an ALIF or OLIF and then a TFS according to Boucher technique using spinal navigation (O-arm). No peri-operative complication occurred, and all the screws were successfully positioned (n = 10). All clinical scores (ODI, VAS L and VAS R) improved at 6-month follow-up. Segmental lordosis increased from 6° [2.4°-12°] to 13.6° [8°-17°]. Fusion was achieved for the five patients. TFS using O-arm in addition to ALIF/OLIF is feasible. To confirm our early favourable outcomes on clinical and radiological data, this technique must be evaluated on larger samples of patients.

Use of Intraoperative Computed Tomography Improves Outcome of Minimally Invasive Transforaminal Lumbar Interbody Fusion: A Single-Center Retrospective Cohort Study

OBJECTIVE

To provide data about surgical workflow, accuracy, complications, radiation exposure, and learning curve effect in patients who underwent minimally invasive (MIS) transforaminal lumbar interbody fusion with navigation coupled with mobile intraoperative computed tomography.

METHODS

A retrospective analysis was performed of data from consecutive patients who underwent single- or double-level MIS transforaminal lumbar interbody fusion at a single institution; mobile intraoperative computed tomography combined with a navigation system was used as the sole intraoperative imaging method to place pedicular screws; decompression and interbody fusion were performed through a 22-mm tubular retractor. Clinical data, perioperative complications, accuracy of pedicular screw placement, and radiation exposure were analyzed. A learning curve effect on surgical time and accuracy was assessed.

RESULTS

A total of 408 screws in 100 patients were analyzed. In all cases, spinal navigation allowed for identification of pedicular trajectories and greatly facilitated nerve root decompression through the MIS approach. Overall accuracy according to Heary classification was 95.3%. Nineteen screws (4.7%) presented a minor lateral breach (<2 mm), not clinically significant. Surgical time, blood loss, and patient radiation exposure compared favorably with reported values from other series using three-dimensional navigation. A learning curve effect on surgical time, but not on screw accuracy, was identified.

CONCLUSIONS

MIS transforaminal lumbar interbody fusion can now be performed without any radiation exposure to the surgeon and operating room staff, with almost absolute accuracy during screw positioning and tubular decompression. A learning curve effect on surgical time, but not on overall screw accuracy, may be expected.

Intraoperative risks of radiation exposure for the surgeon and patient

Intraoperative radiological imaging serves an essential role in many spine surgery procedures. It is critical that patients, staff and physicians have an adequate understanding of the risks and benefits associated with radiation exposure for all involved. In this review, we briefly introduce the current trends associated with intraoperative radiological imaging. With the increased utilization of minimally invasive spine surgery (MIS) techniques, the benefits of intraoperative imaging have become even more important. Less surgical exposure, however, often equates to an increased requirement for intraoperative imaging. Understanding the conventions for radiation measurement, radiological fundamental concepts, along with deterministic or stochastic effects gives a framework for conceptualizing how radiation exposure relates to the risk of various sequela. Additionally, we describe the various options surgeons have for intraoperative imaging modalities including those based on conventional fluoroscopy, computer tomography, and magnetic resonance imaging. We also describe different ways to prevent unnecessary radiation exposure including dose reduction, better education, and use of personal protective equipment (PPE). Finally, we conclude with a reflection on the progress that has been made to limit intraoperative radiation exposure and the promise of future technology and policy.

Device profile of the XVision-spine (XVS) augmented-reality surgical navigation system: overview of its safety and efficacy

Introduction: The field of augmented reality mediated spine surgery is growing rapidly and holds great promise for improving surgical capabilities and patient outcomes. Augmented reality can assist with complex or atypical cases involving challenging anatomy. As neuronavigation evolves, fundamental technical limitations remain in line-of-sight interruption and operator attention shift, which this novel augmented reality technology helps to address.Areas covered: XVision is a recently FDA-approved head mounted display for intraoperative neuronavigation, compatible with all current conventional pedicle screw technology. The device is a wireless, customizable headset with an integrated surgical tracking system and transparent retinal display. This review discusses the available literature on the safety and efficacy of XVision, as well as the current state of augmented reality technology in spine surgery.Expert opinion: Augmented-reality spine surgery is an emerging technology that may increase precision, efficiency, and safety as well as decrease radiation exposure of manual and robotic computer-navigated pedicle screw insertion techniques. The initial clinical experience with XVision has shown good outcomes and it has received positive operator feedback. Now that initial clinical safety and efficacy has been demonstrated, ongoing experience must be studied to empirically validate this technology and generate further innovation in this rapidly evolving field.

Effective dose and image quality for intraoperative imaging with a cone-beam CT and a mobile multi-slice CT in spinal surgery: A phantom study

PURPOSE

To compare the effective dose (ED) and image quality (IQ) of O-arm cone-beam CT (Medtronic, Minneapolis, MN, USA) and Airo multi-slice CT (Brainlab AG, Munich, Germany) for intraoperative-CT (i-CT) in spinal surgery.

METHODS

The manufacturer-defined protocols available in the O-arm and Airo systems for three-dimensional lumbar spine imaging were compared. Organ dose was measured both with thermo-luminescent dosimeters and GafChromic films in the Alderson RadiationTherapy anthropomorphic phantom. A subjective analysis was performed by neurosurgeons to compare the clinical IQ of the anthropomorphic phantom images acquired with the different i-CT systems and imaging protocols. Image uniformity, noise, contrast-to-noise-ratio (CNR), and spatial resolution were additionally assessed with the Catphan 504 phantom.

RESULTS

O-arm i-CT caused 56% larger ED than Airo due to the high definition (HD) imaging protocol. The noise was larger for O-arm images leading to a lower CNR than that measured for Airo. Moreover, scattering and beam hardening effects were observed in the O-arm images. Better spatial resolution was measured for the O-arm system (9 lp/cm) than for Airo (4 lp/cm). For all the investigated protocols, O-arm was found to be better for identifying anatomical features important for accurate pedicle screw positioning.

CONCLUSIONS

According to phantom measurements, the HD protocol of O-arm offered better clinical IQ than Airo but larger ED. The larger noise of O-arm images did not compromise the clinical IQ while the superior spatial resolution of this system allowed a better visibility of anatomical features important for pedicle screw positioning in the lumbar region.

Fluoroscopy time analysis of a prospective, multi-centre study comparing robotic- and fluoroscopic-guided placement of percutaneous pedicle screw instrumentation for short segment minimally invasive lumbar fusion surgery

BACKGROUND

As minimally invasive spine surgery becomes more widespread, concerns regarding radiation exposure to surgeons and patients alike have become a growing concern. Robotic guidance has been developed as a way to increase the accuracy of instrumentation while decreasing radiation burden.

METHODS

A retrospective analysis of a large, multi-centre, prospective study comparing robotic-guided (RG) to fluoroscopic-guided (FG) (Multi-centre, Partially Randomized, Controlled Trial of MIS Robotic vs. Freehand in Short Adult Degenerative Spinal Fusion Surgeries) was performed to evaluate for differences in radiation exposure between study groups.

RESULTS

RG was associated with 78.3% (p < 0.001) and 79.8% (p < 0.001) reduction in total and per screw fluoroscopy times, respectively, as compared to FG. RG was also associated with a 50.8% (p < 0.001) reduction in total operative fluoroscopy time.

CONCLUSIONS

RG was associated with significantly lower fluoroscopy times compared to FG. This suggests that utilization of robotic navigation systems may result in decreased operative radiation exposure, which is a growing concern for surgeons performing minimally invasive spine surgery.

A New Technique that Combines Navigation-Assisted Lateral Interbody Fusion and Percutaneous Placement of Pedicle Screws in the Lateral Decubitus Position with the Surgeon Using Wearable Smart Glasses: A Small Case Series and Technical Note

BACKGROUND

We describe a new technique that combines navigation-assisted extreme lateral interbody fusion (NALIF) and percutaneous placement of pedicle screws in the lateral decubitus position with the surgeon using wearable smart glasses.

METHODS

We explain our method for nonfluoroscopic NALIF and single-position (SP)- percutaneous pedicle screw (PPS) surgery for patients with degenerative lumbar diseases using wearable smart glasses. The wearable smart glasses provide a semitransparent overlay of the navigation information onto the image seen through the lenses. This technique does not require fluoroscopy during lateral interbody fusion or PPS insertion. It is convenient because it does not require a Jamshidi needle or guidewire when inserting PPSs.

RESULTS

Using this method, the surgeon can glance at the 3-dimensional images on the wearable smart glasses while still viewing the operation field. A review of 24 cases yielded an average operation time of 89.5 ± 16.4 minutes and 66.7 ± 67.0 mL of blood loss, without any severe intra- or postoperative complications.

CONCLUSIONS

Nonfluoroscopic NALIF and SP-PPS placement surgery is a safe and effective means for implanting cages and PPSs in this minimally invasive approach without compromising the results. Although further investigations are needed, the wearable smart glasses may be a useful surgical aid when performing NALIF and SP-PPS placement in patients with degenerative lumbar diseases.

Patients' and Physicians' Knowledge of Radiation Exposure Related to Spine Surgery

STUDY DESIGN

Cross-sectional survey.

OBJECTIVE

Examine patients' and physicians' estimates of radiation exposure related to spine surgery.

SUMMARY OF BACKGROUND DATA

Patients are commonly exposed to radiation when undergoing spine surgery. Previous studies suggest that patients and physicians have limited knowledge about radiation exposure in the outpatient setting. This has not been assessed for intraoperative imaging.

METHODS

A questionnaire was developed to assess awareness/knowledge of radiation exposure in outpatient and intraoperative spine care settings. Patients and surgeons estimated chest radiograph (CXR) equivalent radiation from: cervical and lumbar radiographs (anterior-posterior [AP] and lateral), computed tomography (CT), magnetic resonance imaging (MRI), intraoperative fluoroscopy, and intraoperative CT (O-arm). Results were compared to literature-reported radiation doses.

RESULTS

Overall, 100 patients and 26 providers completed the survey. Only 31% of patients were informed about outpatient radiation exposure, and only 23% of those who had undergone spine surgery had been informed about intraoperative radiation exposure. For lumbar radiographs, patients and surgeons underestimated CXR-equivalent radiation exposures: AP by five-fold (P < 0.0001) and seven-fold (P < 0.0001), respectively, and lateral by three-fold (P < 0.0001) and four-fold (P = 0.0002), respectively. For cervical CT imaging, patients and surgeons underestimated radiation exposure by 18-fold (P < 0.0001) and two-fold (P = 0.0339), respectively. For lumbar CT imaging, patients and surgeons underestimated radiation exposure by 31-fold (P < 0.0001) and three-fold (P = 0.0001), respectively. For intraoperative specific cervical and lumbar imaging, patients underestimated radiation exposure for O-arm by 11-fold (P < 0.0001) and 22-fold (P = 0.0002), respectively. Surgeons underestimated radiation exposure of lumbar O-arm by three-fold (P = 0.0227).

CONCLUSION

This study evaluated patient and physician knowledge of radiation exposure related to spine procedures. Underestimation of radiation exposure in the outpatient setting was consistent with prior study findings. The significant underestimation of intraoperative cross-sectional imaging (O-arm) is notable and needs attention in the era of increased use of such technology for imaging, navigation, and robotic spine surgery.

LEVEL OF EVIDENCE

4.

A novel computer navigation model guided unilateral percutaneous vertebroplasty for vertebral compression fracture: A case report

RATIONAL

Vertebral compression fracture (VCF) is one of the most common diseases in spinal surgery. Traditional percutaneous vertebroplasty (PVP) under fluoroscopy is an effective method to treat vertebral compression fracture. However, there is still a risk of vascular nerve injury and infection caused by inaccurate or repeated puncture. Therefore, the purpose of this paper was to assess the accuracy of unilateral PVP guided by screw view model of navigation (SVMN) for VCF.

PATIENT CONCERNS

A 59-year-old female patient suffered high falling injury, and with back pain as its main clinical symptom.

DIAGNOSES

The patient was diagnosed with a L1 VCF.

INTERVENTIONS

We placed the puncture needle under the guidance of SVMN to reach the ideal position designed before operation, and then injected the bone cement to complete the percutaneous kyphoplasty (PKP).

OUTCOMES

The operative time was 29.5 minutes, the puncture time was 1 time, the fluoroscopy time was 2.9 minutes, and the bone cement distribution was satisfactory. VAS and ODI scores were significant improved postoperatively. No surgical complications, including neurovascular injury and infection, were observed during 28-month follow up.

LESSONS

The SVMN guided percutaneous puncture needle insertion in PKP operation for VCF is an effective and safety technique. Besides, the SVMN has also been a contributor to reduce radiation doses and replace conventional fluoroscopy.

3D-imaging in percutaneous spine surgery using the Surgivisio system

The Surgivisio system is a new generation of intraoperative 3D imaging, used in our institution for pedicle insertion in minimally invasive spine surgery since January 2018. The purpose of this technical note is to describe the Surgivisio system, its advantages and its limitations, in percutaneous spinal surgery. Results of the first year of use were analyzed, in a series of 29 patients, to evaluate accuracy of pedicle screw insertion, operative time and radiation exposure. On the Heary and Gertzbein classifications, 95.5% of pedicle screw placements (107/112) were rated as acceptable. Mean operative time was 29.3min per vertebra; mean radiation exposure per vertebra was 0.61 mSv. The Surgivisio system is an effective navigation tool for pedicle screw insertion in minimally invasive spinal surgery, with acceptable radiation exposure and operative time for each navigated vertebra. LEVEL OF EVIDENCE: II, prospective cohort study.

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.

Ten-Step Biportal Endoscopic Transforaminal Lumbar Interbody Fusion Under Computed Tomography-Based Intraoperative Navigation: Technical Report and Preliminary Outcomes in Mexico

BACKGROUND

The principal advantage of intraoperative spinal navigation is the ease of screw placement. However, visualization and the integration of navigation can be explored with the use of navigation-guided full-endoscopic techniques.

OBJECTIVE

To describe the stepwise intraoperative navigation-assisted unilateral biportal endoscopic transforaminal lumbar interbody fusion (UBE-TLIF) technique and to present our preliminary results in a Mexican population.

METHODS

A 10-step summary of the UBE-TLIF operative technique was described, and the clinical and radiological results are presented and analyzed.

RESULTS

A total of 7 patients were treated. We observed the value of integrating navigation and endoscopic visualization when decompression had to be performed.

CONCLUSION

Together, intraoperative navigation and direct visualization through the endoscope may be a useful surgical tool for surgeons with experience in endoscopic spinal surgery.

The Application of O-arm and Navigation System in Precise Localization of Spinal Cord lesions: a Case Series study

OBJECTIVE

To study on the clinical efficacy of precise localization of O-arm and navigation system in spinal cord lesions.

METHODS

From Augst 2015 to September 2019, 22 patients with spinal cord lesions were arranged in the group.The intraoperative cross-sectional images were acquired by O-arm image system, which were transferred to the Stealth navigation system, and fused with pre-opreative MRI images. The image fusion was completed by the Medtronic Synergy Cranial software. The fused images were used to locate spinal cord lesions, assisted by the navigation system. The navigation errors were evaluated by measuring the maximum distance between the end of the lesion in MRI and its real position.

RESULTS

The image fusion were completed in all patients, and we successfully completed the image-guided surgeries of the spinal cord lesions. The time of image processing was between 7 min and 19 min, and the mean value was 15.1 ± 2.2 min. The navigation error was between 0.9 mm and 5.3 mm, the mean value was 1.6 ± 0.9 mm.

CONCLUSION

The application of precise localization of O-arm and navigation system in spinal cord lesions is clinically reliable and feasible.

Technical Considerations of Interlaminar Approach for Lumbar Disc Herniation

With the evolution of endoscopic instruments and techniques, full-endoscopic spine surgery has attracted more attention worldwide in recent years. At the initial stage, surgeons conducted endoscopic lumbar discectomy using the transforaminal approach. Next, interlaminar endoscopic lumbar discectomy was developed to treat a herniation disc at the L5-S1 level. The progression in interlaminar endoscopic techniques has further broadened the indications for full-endoscopic spine surgery. However, the steep learning curve of endoscopic procedures has remained challenging. The use of interlaminar endoscopic lumbar discectomy entails many essential skills to manage the different anatomical structures of the spine. From the perspective of successful and safe interlaminar endoscopic lumbar discectomy, we have discussed the technical considerations for endoscopic procedures.

Overview of Minimally Invasive Spine Surgery

Minimally invasive spine surgery (MISS) has continued to evolve over the past few decades, with significant advancements in technology and technical skills. From endonasal cervical approaches to extreme lateral lumbar interbody fusions, MISS has showcased its usefulness across all practice areas of the spine, with unique points of access to avoid pertinent neurovascular structures. Adult spine deformity has also recognized the importance of minimally invasive techniques in its ability to limit complications and to provide adequate sagittal alignment correction and improvements in patients' functional status. Although MISS has continued to make significant progress clinically, consideration must also be given to its economic impact and the learning curve surgeons experience in adding these procedures to their armamentarium. This review examines current innovations in MISS, as well as the economic impact and future directions of the field.

O-arm navigation versus C-arm guidance for pedicle screw placement in spine surgery: a systematic review and meta-analysis

BACKGROUND

O-arm and C-arm are commonly used in spine surgery to guide pedicle screw placement. However, concerning the accuracy and efficiency of them, no systematical review and meta-analyses are available to help surgeons make comparisons.

PURPOSES

This study aims to investigate the accuracy and efficiency of O-arm-navigated versus C-arm-guided pedicle screw placement in thoracic and lumbar spine surgery. It would help surgeons choose the optimal technique for pedicle screw placement.

PATIENTS AND METHODS

A systematic review and meta-analyses were performed after searching the PubMed, Embase, and Cochrane databases to identify all studies that assessed the accuracy and efficiency of navigation coupled with O-arm and conventional C-arm fluoroscopy.

RESULTS

Eight studies were finally recruited in this systematic review, all of which reported pedicle screw placement outcomes related to accuracy or efficiency in both C-arm and O-arm groups. Five studies showed higher screw insertion accuracy in the O-arm group, while one study showed no significant difference. And the pooled results also indicated that the incidence of screw misplacement in the C-arm groups is higher. Moreover, the pooled results from five studies indicated no significant difference in insertion time between C-arm and O-arm.

CONCLUSIONS

Navigation coupled with O-arm imaging displayed a lower efficiency outcome in pedicle screw placement compared to conventional C-arm fluoroscopy. However, in terms of accuracy, O-arm navigation had significant advantages in accuracy over conventional C-arm fluoroscopy.

A Review of Techniques, Time Demand, Radiation Exposure, and Outcomes of Skin-anchored Intraoperative 3D Navigation in Minimally Invasive Lumbar Spinal Surgery

STUDY DESIGN

Retrospective cohort.

OBJECTIVE

To describe our technique for and evaluate the time demand, radiation exposure and outcomes of skin-anchored intraoperative three-dimensional navigation (ION) in minimally invasive (MIS) lumbar surgery, and to compare these parameters to 2D fluoroscopy for MI-TLIF.

SUMMARY OF BACKGROUND DATA

Limited visualization of anatomic landmarks and narrow access corridor in MIS procedures result in greater reliance on image guidance. Although two-dimensional fluoroscopy has historically been used, ION is gaining traction.

METHODS

Patients who underwent MIS lumbar microdiscectomy, laminectomy, or MI-TLIF using skin-anchored ION and MI-TLIF by the same surgeon using 2D fluoroscopy were selected. Operative variables, radiation exposure, and short-term outcomes of all procedures were summarized. Time-demand and radiation exposure of fluoroscopy and ION for MI-TLIF were compared.

RESULTS

Of the 326 patients included, 232 were in the ION cohort (92 microdiscectomies, 65 laminectomies, and 75 MI-TLIFs) and 94 in the MI-TLIF using 2D fluoroscopy cohort. Time for ION setup and image acquisition was a median of 22 to 24 minutes. Total fluoroscopy time was a median of 10 seconds for microdiscectomy, 9 for laminectomy, and 26 for MI-TLIF. Radiation dose was a median of 15.2 mGy for microdiscectomy, 16.6 for laminectomy, and 44.6 for MI-TLIF, of this, 93%, 95%, and 37% for microdiscectomy, laminectomy, and MI-TLIF, respectively were for ION image acquisition, with the rest attributable to the procedure. There were no wrong-level surgeries. Compared with fluoroscopy, ION for MI-TLIF resulted in lower operative times (92 vs. 108 min, P < 0.0001), fluoroscopy time (26 vs. 144 s, P < 0.0001), and radiation dose (44.6 vs. 63.1 mGy, P = 0.002), with equivalent time-demand and length of stay. ION lowered the radiation dose by 29% for patients and 55% for operating room personnel.

CONCLUSION

Skin-anchored ION does not increase time-demand compared with fluoroscopy, is feasible, safe and accurate, and results in low radiation exposure.

LEVEL OF EVIDENCE

3.

Percutaneous placement of lumbar pedicle screws via intraoperative CT image-based augmented reality-guided technology

OBJECTIVE

The authors aimed to assess, in a bone-agar experimental setting, the feasibility and accuracy of percutaneous lumbar pedicle screw placements using an intraoperative CT image-based augmented reality (AR)-guided method compared to placements using a radiograph-guided method. They also compared two AR hologram alignment methods.

METHODS

Twelve lumbar spine sawbones were completely embedded in hardened opaque agar, and a cubic marker was fixed on each phantom. After intraoperative CT, a 3D model of each phantom was generated, and a specialized application was deployed into an AR headset (Microsoft HoloLens). One hundred twenty pedicle screws, simulated by Kirschner wires (K-wires), were placed by two experienced surgeons, who each placed a total of 60 screws: 20 placed with a radiograph-guided technique, 20 with an AR technique in which the hologram was manually aligned, and 20 with an AR technique in which the hologram was automatically aligned. For each K-wire, the insertion path was expanded to a 6.5-mm diameter to simulate a lumbar pedicle screw. CT imaging of each phantom was performed after all K-wire placements, and the operative time required for each K-wire placement was recorded. An independent radiologist rated all images of K-wire placements. Outcomes were classified as grade I (no pedicle perforation), grade II (screw perforation of the cortex by up to 2 mm), or grade III (screw perforation of the cortex by > 2 mm). In a clinical situation, placements scored as grade I or II would be acceptable and safe for patients.

RESULTS

Among all screw placements, 75 (94%) of 80 AR-guided placements and 40 (100%) of 40 radiograph-guided placements were acceptable (i.e., grade I or II; p = 0.106). Radiograph-guided placements had more grade I outcomes than the AR-guided method (p < 0.0001). The accuracy of the two AR alignment methods (p = 0.526) was not statistically significantly different, and neither was it different between the AR and radiograph groups (p < 0.0001). AR-guided placements required less time than the radiograph-guided placements (mean ± standard deviation, 131.76 ± 24.57 vs 181.43 ± 15.82 seconds, p < 0.0001). Placements performed using the automatic-alignment method required less time than those using the manual-alignment method (124.20 ± 23.80 vs 139.33 ± 23.21 seconds, p = 0.0081).

CONCLUSIONS

In bone-agar experimental settings, AR-guided percutaneous lumbar pedicle screw placements were acceptable and more efficient than radiograph-guided placements. In a comparison of the two AR-guided placements, the automatic-alignment method was as accurate as the manual method but more efficient. Because of some limitations, the AR-guided system cannot be recommended in a clinical setting until there is significant improvement of this technology.

Defining the MIS-TLIF: A Systematic Review of Techniques and Technologies Used by Surgeons Worldwide

STUDY DESIGN

Systematic review.

OBJECTIVE

To date there is no consensus among surgeons as to what defines an MIS-TLIF (transforaminal lumbar interbody fusion using minimally invasive spine surgery) compared to an open or mini-open TLIF. This systematic review aimed to examine the MIS-TLIF techniques reported in the recent body of literature to help provide a definition of what constitutes the MIS-TLIF, based on the consensus of the majority of surgeons.

METHODS

We created a database of articles published about MIS-TLIF between 2010 and 2018. We evaluated the technical components of the MIS-TLIF including instruments and incisions used as well the order in which key steps are performed.

RESULTS

We could identify several patterns for MIS-TLIF performance that seemed agreed upon by the majority of MIS surgeons: use of paramedian incisions; use of a tubular retractor to perform a total facetectomy, decompression, and interbody cage implantation; and percutaneous insertion of the pedicle-screw rod constructs with intraoperative imaging.

CONCLUSION

Based on this review of the literature, the key features used by surgeons performing MIS TLIF include the use of nonexpandable or expandable tubular retractors, a paramedian or lateral incision, and the use of a microscope or endoscope for visualization. Approaches using expandable nontubular retractors, those that require extensive subperiosteal dissection from the midline laterally, or specular-based retractors with wide pedicle to pedicle exposure are far less likely to be promoted as an MIS-based approach. A definition is necessary to improve the communication among spine surgeons in research as well as patient education.

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.