Usefulness of a navigation system in surgery for scoliosis: segmental pedicle screw fixation in the treatment

Comparison of Radiographic and Patient-Reported Outcomes After Surgery in Adolescent Idiopathic Scoliosis Between Robotics and Navigation: An Analysis Using Propensity Score Matching

Purpose This study aimed to compare the radiographic and patient-reported outcomes after surgery in adolescent idiopathic scoliosis (AIS) between robotics and navigation using propensity score matching. Methods This retrospective study involved 50 patients undergoing posterior spinal fusion for AIS between October 2016 and August 2022, utilizing navigation or robotic systems, analyzing them using propensity score matching. The evaluations included assessments using X-ray, Scoliosis Research Society 22-Item (SRS-22) Questionnaire, and CT, considering variables such as age, gender, BMI, and Lenke type. Results Post matching, 13 cases each from robotics and navigation groups were compared. No significant differences were found in the demographic variables, preoperative X-ray parameters, and preoperative SRS-22 scores between the two groups. The robotics group demonstrated a higher perfect accuracy rate (94.0% vs. 84.7%, p=0.005) and a lower deviation rate in pedicle screw placements (1.6% vs. 4.1%, p=0.223). At one year postoperatively, there were no significant differences in the X-ray parameters between both groups. Likewise, no significant differences were found in each domain of SRS-22, but function, self-image, mental health, and satisfaction scores were numerically higher in the robotics group. Conclusion The application of a spinal robotic system in AIS surgery presented enhanced screw accuracy and lower deviation rates, compared to navigation, with no significant differences observed in the X-ray parameters and each domain of SRS-22 at one year postoperatively. This suggests that, to improve patient quality of life (QOL), it is essential for robotic-assisted spine surgery to focus not only on screw accuracy but also on the development of novel robotic-assisted techniques.

Safety of robotic-assisted screw placement for spine surgery: Experience from the initial 125 cases

BACKGROUND

The present study aimed to evaluate the safety of robot-assisted screw placement in 125 cases after introducing a spinal robotics system and to identify the situations where deviation was likely to occur.

METHODS

The subjects were 125 consecutive patients who underwent robotic-assisted screw placement using a spinal robotics system (Mazor X Stealth Edition, Medtronic) from April 2021 to January 2023. The 1048 screws placed with robotic assistance were evaluated. We investigated intraoperative adverse events of the robotics system and complications occurring within 30 days after surgery. We evaluated screw accuracy and deviation and compared them for vertebral levels, screw insertion methods (open traditional pedicle screw [Open-PS], cortical bone trajectory screw [CBT], percutaneous pedicle screw [PPS], and S2 alar iliac screw [S2AIS]), diagnosis, and phases of surgical cases.

RESULTS

The deviation rate of robotic-assisted screw placement for spine surgery was 2.2%. Complications were reoperation due to implant-related neurological deficit in 0.8% and surgical site infection in 0.8%. There was significant difference in the deviation rate between vertebral levels. The deviation rate of the T1-T4 level was high at 10.0%. There was significant difference in the deviation rate between Open-PS, CBT, PPS, and S2AIS. The PPSs had a high deviation rate of 10.3%. The deviation rates were not significantly different between patients with and without deformity. The deviation rate did not change depending on the experience of surgical cases, and the deviation rate was favorable from the onset.

CONCLUSION

Although the robotic-assisted screw placement was safe, we should be extra vigilant when placing screws in the upper thoracic region (deviation rate 10.0%) and when using PPSs (deviation rate 10.3%).

Accuracy of computer-assisted pedicle screw placement for adolescent idiopathic scoliosis: a comparison between robotics and navigation

PURPOSE

To compare the accuracy of pedicle screw placement in adolescent idiopathic scoliosis (AIS) between robotics and navigation and clarify the factors that cause screw deviation when robotics is used.

METHODS

Fifty consecutive patients who underwent posterior spinal fusions with computer-assisted pedicle screw placement including robotics and navigation for AIS were included. A total of 741 pedicle screws (250: Robot group, 491: Navi group) were evaluated on postoperative CT images. A rate of penetration of ≥ 2 mm was calculated as the deviation rate. After propensity score matching, we examined vertebral levels, the distance from the reference frame (RF), and the pedicle channel grade as factors for deviation.

RESULTS

The deviation rate was significantly lower in the Robot group than in the Navi group (Robot group: 1.6%, Navi group: 7.5%). After propensity score matching, 22 cases were extracted. At T5-T8, the deviation rate of the Robot group was significantly lower than that of the Navi group. In the Robot group, the T2-T4 deviation rate was significantly higher than at the other vertebral levels. The distance from the RF didn't affect the deviation rate. The deviation rate of pedicle channel Grade 4 (inner diameter of less than 1 mm) was significantly higher than for the other grades.

CONCLUSION

The deviation rate of robotics was 1.6%, lower than that of navigation. The narrow pedicles with an inner diameter of less than 1 mm (deviation rate: 22.2%) and the upper thoracic level (deviation rate: 14.3%) were factors related to screw deviation even when using robotics.

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.

Intraoperative 3D Imaging Reduces Pedicle Screw Related Complications and Reoperations in Adolescents Undergoing Posterior Spinal Fusion for Idiopathic Scoliosis: A Retrospective Study

Widely used surgical treatment for adolescent idiopathic scoliosis (AIS) is posterior spinal fusion using pedicle screw instrumentation (PSI). Two-dimensional (2D) or three-dimensional (3D) navigation is used to track the screw positioning during surgery. In this study, we evaluated the screw misplacement, complications, and need for reoperations of intraoperative 3D as compared to 2D imaging in AIS patients. There were 198 adolescents, of which 101 (51%) were evaluated with 2D imaging and 97 (49%) with 3D imaging. Outcome parameters included radiographic correction, health-related quality of life (HRQOL), complications, and reoperations. The mean age was 15.5 (SD 2.1) years at the time of the surgery. Forty-four (45%) patients in the 3D group and 13 (13%) patients in the 2D group had at least one pedicle screw repositioned in the index operation (p < 0.001). Six (6%) patients in the 2D group, and none in the 3D group had a neurological complication (p = 0.015). Five (5%) patients in the 2D group and none in the 3D group required reoperation (p = 0.009). There were no significant differences in HRQOL score at two-year follow-up between the groups. In conclusion, intraoperative 3D imaging reduced pedicle screw-related complications and reoperations in AIS patients undergoing PSI as compared with 2D imaging.

Does Three-dimensional Printing Plus Pedicle Guider Technology in Severe Congenital Scoliosis Facilitate Accurate and Efficient Pedicle Screw Placement?

BACKGROUND

Three-dimensional (3-D) printing offers the opportunity to create patient-specific guides for pedicle screw placement based on CT-generated models. This technology might allow for more-accurate placement of pedicle screws in patients with severe congenital scoliosis who have rotated vertebrae and small pedicles, but to our knowledge, this premise has not been tested.

QUESTIONS/PURPOSES

(1) Is the use of 3-D printing and pedicle guider technology as or more accurate than the use of the freehand technique for pedicle-screw placement in patients with severe congenital scoliosis? (2) Does surgical time differ with the use of these guiders? (3) Are complications less common in patients treated with this new approach to pedicle-screw placement?

METHODS

A prospective controlled study was conducted of patients with severe congenital scoliosis (major curve ≥ 90°) from June 2016 to June 2018. During this period, we treated 93 patients with congenital scoliosis; 32 had severe scoliosis with a major curve ≥ 90°. The patients were divided into a pedicle guider group (n = 15) and a control group (n = 17) based on their willingness to use pedicle guider technology, which was considered a research technology. With the numbers available, there were no between-group differences in terms of age, sex, BMI, or parameters related to curve severity or flexibility, and all patients in both groups had severe curves. Preoperative and postoperative low-dose CT scans were performed in the two groups. In the pedicle guider group, custom software was used to design the pedicle guider, and a 3-D printer was used to print a physical spinal model and pedicle guiders. The pedicle guiders were tested on the surface of the physical spinal model before surgery to ensure proper fit, and then used to assist pedicle screw placement during surgery. A total of 244 screws were implanted with the help of 127 pedicle guiders (254 guiding tunnels) during surgery in the PG group. Five predesigned pedicle guiders were abandoned due to an unstable match, and the success rate of assisted screw placement using a pedicle guider was 96% (244 of 254). The freehand technique was used in the control group, which relied on anatomic localization to place pedicle screws. The accuracy of pedicle screw placement was evaluated with CT scans, which revealed whether screws had broken through the pedicle cortex. We compared the groups in terms of accuracy (defined as unanticipated breaches less than 2 mm), surgical time, time to place pedicle screws, and screw-related complications.

RESULTS

A higher proportion of the screws placed using pedicle guider technology were positioned accurately than were in the control group (93% [227 of 244] versus 78% [228 of 291]; odds ratio, 3.69 [95% CI, 2.09-6.50]; p<0.001). With pedicle guider use, operative time (296 ± 56 versus 360 ± 74; 95% CI, -111 to -17; p = 0.010), time to place all screws (92 ± 17 versus 118 ± 21; 95% CI, -39 to -12; p = 0.001), and mean time to place one screw (6 ± 1 versus 7 ± 1; 95% CI, -2 to 0; p = 0.011) decreased. One patient in the pedicle guider group and four in the control group experienced screw-related complications; the sample sizes and small number of complications precluded statistical comparisons.

CONCLUSIONS

In this small, preliminary study, we showed that the accuracy of the surgical technique using spinal 3-D printing combined with pedicle guider technology in patients with severe congenital scoliosis was higher than the accuracy of the freehand technique. In addition, the technique using pedicle guider technology appeared to shorten operative time. If these findings are confirmed in a larger study, pedicle guider technology may be helpful for situations in which intraoperative CT or O-arm navigation is not available.

LEVEL OF EVIDENCE

Level II, therapeutic study.

Accuracy of Current Techniques for Placement of Pedicle Screws in the Spine: A Comprehensive Systematic Review and Meta-Analysis of 51,161 Screws

BACKGROUND

Pedicle screws (PSs) are routinely used for stabilization to enhance fusion in a variety of spinal diseases. Although the accuracy of different PS placement methods has been previously reported, most of these studies have been limited to 1 or 2 techniques. The purpose was to determine the current accuracy of PS placement among 4 modalities of PS insertion (freehand [FH], fluoroscopy-assisted [FA], computed tomography navigation-guided [CTNav], and robot-assisted [RA]) and analyze variables associated with screw misplacement.

METHODS

A systematic review was performed of peer-reviewed articles reporting PS accuracy of 1 technique from January 1990 to June 2018. Accuracy of PS placement, PS insertion technique, and pedicle breach (PB) data were collected. A meta-analysis was performed to estimate the overall pooled (OP) rates of PS accuracy as a primary outcome, stratified by screw insertion techniques. Potential determinants were analyzed via meta-regression analyses.

RESULTS

Seventy-eight studies with 7858 patients, 51,161 PSs, and 3614 cortical PBs were included. CTNav showed the highest PS placement accuracy compared with other techniques: OP accuracy rates were 95.5%, 93.1%, 91.5%, and 90.5%, via CTNav, FH, FA, and RA techniques, respectively. RA and CTNav were associated with the highest PS accuracy in the thoracic spine, compared with FH.

CONCLUSIONS

The OP data show that CTNav has the highest PS accuracy rates. Thoracic PSs were associated with lower accuracy rates; however, RA showed fewer breaches in the thoracic spine compared with FH and FA. Given the heterogeneity among studies, further standardized and comparative investigations are required to confirm our findings.

Differences between Manufacturers of Computed Tomography-Based Computer-Assisted Surgery Systems Do Exist: A Systematic Literature Review

STUDY DESIGN

Literature review.

OBJECTIVE

Several studies have shown that the accuracy of pedicle screw placement significantly improves with use of computed tomography (CT)-based navigation systems. Yet, there has been no systematic review directly comparing accuracy of pedicle screw placement between different CT-based navigation systems. The objective of this study is to review the results presented in the literature and compare CT-based navigation systems relative only to screw placement accuracy.

METHODS

Data sources included CENTRAL, Medline, PubMed, and Embase databases. Studies included were randomized clinical trials, case series, and case-control trials reporting the accuracy of pedicle screws placement using CT-based navigation. Two independent reviewers extracted the data from the selected studies that met our inclusion criteria. Publications were grouped based on the CT-based navigation system used for pedicle screw placement.

RESULTS

Of the 997 articles we screened, only 26 met all of our inclusion criteria and were included in the final analysis, which showed a significant statistical difference (p < 0.0001, 95% confidence interval 0.92 to 1.23) in accuracy of pedicle screw placement between three different CT-based navigation systems. The mean (weighted) accuracy of pedicle screws placement based on the CT-based navigation system was found to be 97.20 ± 2.1% in StealthStation (Medtronic, United States) and 96.1 ± 3.9% in VectorVision (BrainLab, Germany).

CONCLUSION

This review summarizes results presented in the literature and compares screw placement accuracy using different CT-based navigation systems. Although certain factors such as the extent of the procedure and the experience and skills of the surgeon were not accounted for, the differences in accuracy demonstrated should be considered by spine surgeons and should be validated for effects on patients' outcome.

Learning curve of 3D fluoroscopy image-guided pedicle screw placement in the thoracolumbar spine

BACKGROUND CONTEXT

During the past decade, a disproportionate increase of spinal fusion procedures has been observed. Along with this trend, image-guided spine surgery has been experiencing a renaissance in the recent years. A wide range of different navigation systems are available on the market today. However, only few published studies assess the learning curves concerning these new spinal navigation techniques. So far, a study on the learning curve for intraoperative three-dimensional fluoroscopy (3DFL)-navigated pedicle screw (PS) placement is still lacking.

PURPOSE

The purpose of the study was to analyze the learning curve for 3DFL-navigated thoracolumbar PS placement.

STUDY DESIGN/SETTING

The study design included a prospective case series.

PATIENT SAMPLE

A cohort of 145 patients were recruited from January 2011 to June 2012.

OUTCOME MEASURES

The outcome measures were duration of intraoperative 3D scans, PS placement, PS accuracy on postoperative computed tomography (CT) scans, and PS-related revisions and complications.

METHODS

From the introduction of spinal navigation to our department in January 2011 until June 2012, the learning curve for the duration of intraoperative 3D scan acquisition (navigation or control scan) and placement time per screw, intraoperative screw revisions, screw-related complications, revision surgeries, and PS accuracy on postoperative CT scans were assessed in 145 patients undergoing dorsal navigated instrumentation for 928 PS (736 lumbosacral and 192 thoracic). The observed time span was divided into four intervals. Results of the second, third, and last periods were compared with the first (reference) period, respectively.

RESULTS

The mean navigation 3D scan time decreased (first and fourth periods) from 15.4±7.8 (range, 4-40) to 8.4±3.3 (3-15) minutes (p<.001). The mean control 3D scan time (after PS placement) decreased from 11.2±4.8 (5-25) to 6.6±3.0 (3-15) minutes (p<.001). The mean PS insertion time decreased from 5.3±2.5 (1-15) to 3.2±2.3 (1-17) minutes (p<.001). The mean proportion of correctly positioned PS (all 928) according to the Gertzbein and Robbins classification grades A and B increased initially from 83.1% (first period) to 95.1% (second period, p=.001), 96.4% (third period, p=.002), and 92.4% (fourth period, p=.049). No learning effect was found with respect to intraoperative screw revisions. There was one revision surgery.

CONCLUSIONS

We could demonstrate significant learning effects for 3DFL-navigated PS placement with regard to intraoperative 3D scan acquisition, PS placement time, and PS accuracy.

Clinical and economic implications of early discharge following posterior spinal fusion for adolescent idiopathic scoliosis

OBJECTIVE

To evaluate the clinical and economic impact of a novel postoperative pathway following posterior spinal fusion (PSF) in patients with adolescent idiopathic scoliosis (AIS).

METHODS

Patient charts were reviewed for demographic data and to determine length of surgery, implant density, use of osteotomies, estimated blood loss, American Society of Anesthesiologists (ASA) score, length of hospital stay, and any subsequent complications. Hospital charges were divided by charge code to evaluate potential savings.

RESULTS

Two hundred and seventy-nine of 365 patients (76.4 %) treated with PSF carried a diagnosis of AIS and had completed 6 months of clinical and radiologic follow-up, a period of time deemed adequate to assess early complications. There was no difference between groups in age at surgery, sex, number of levels fused, or length of follow-up. Patients managed under the accelerated discharge (AD) pathway averaged 1.36 (31.7 %) fewer days of inpatient stay. Operative time was associated with a shorter length of stay. There was no difference in complications between groups. Hospital charges for room and board were significantly less in the AD group ($1.885 vs. $2,779, p < 0.001).

CONCLUSIONS

A pathway aimed to expedite discharge following PSF for AIS decreased hospital stay by nearly one-third without any increase in early complication rate. A small but significant decrease in hospital charges was seen following early discharge. Early discharge following PSF for AIS may be achieved without increased risk of complications, while providing a small cost savings.

Accuracy of image-guided pedicle screw placement using intraoperative computed tomography-based navigation with automated referencing. Part II: thoracolumbar spine

BACKGROUND

Image-guided spinal instrumentation may reduce complications in spinal instrumentation.

OBJECTIVE

To assess accuracy, time efficiency, and staff radiation exposure during thoracolumbar screw instrumentation guided by intraoperative computed tomography (iCT)-based neuronavigation (iCT-N).

METHODS

In 55 patients treated for idiopathic and degenerative deformities, 826 screws were inserted in the thoracic (T2-T12; n = 243) and lumbosacral (L1-S1; n = 545) spine, as well as ilium (n = 38) guided by iCT-N. Up to 17 segments were instrumented following a single automated registration sequence with the dynamic reference arc (DRA) uniformly attached to L5. Accuracy of iCT-N was assessed by calculating angular deviations between individual navigated tool trajectories and final implant positions. Final screw positions were also graded according to established classification systems. Clinical and radiological outcome was assessed at 12 to 14 months.

RESULTS

Additional intraoperative fluoroscopy was unnecessary, eliminating staff radiation exposure. Unisegmental K-wire insertion required 4.6 ± 2.9 minutes. Of the thoracic pedicle screws 98.4% were assigned grades I to III according to the Heary classification, with 1.6% grade IV placement. In the lumbar spine, 94.4% of screws were completely contained (Gertzbein classification grade 0), 4.6% displayed minor pedicle breaches <2 mm (grade 1), and 1% of lumbar screws deviated by >2 to <4 mm (grade 2). The accuracy of iCT-N progressively deteriorates with increasing distance from the DRA, but allows safe instrumentation of up to 12 segments.

CONCLUSION

iCT-N using automated referencing allows for safe, highly accurate multilevel instrumentation of the entire thoracolumbosacral spine and ilium, rendering additional intraoperative imaging dispensable. In addition, automated registration is time-efficient and significantly reduces the need for re-registration in multilevel surgery.

A novel cost-effective computer-assisted imaging technology for accurate placement of thoracic pedicle screws

Object

Use of computer-assisted spine surgery (CASS) technologies, such as navigation systems, to improve the accuracy of pedicle screw (PS) placement is increasingly popular. Despite of their benefits, previous CASS systems are too expensive to be ubiquitously employed, and more affordable and portable systems are desirable. The aim of this study was to introduce a novel and affordable computer-assisted technique that 3-dimensionally visualizes anatomical features of the pedicles and assists in PS insertion. The authors have termed this the 3D-visual guidance technique for inserting pedicle screws (3D-VG TIPS).

Methods

The 3D-VG technique for placing PSs requires only a consumer-class computer with an inexpensive 3D DICOM viewer; other special equipment is unnecessary. Preoperative CT data of the spine were collected for each patient using the 3D-VG TIPS. In this technique, the anatomical axis of each pedicle can be analyzed by volume-rendered 3D models, as with existing navigation systems, and both the ideal entry point and the trajectory of each PS can be visualized on the surface of 3D-rendered images. Intraoperative guidance slides are made from these images and displayed on a TV monitor in the operating room. The surgeon can insert PSs according to these guidance slides. The authors enrolled 30 patients with adolescent idiopathic scoliosis (AIS) who underwent posterior fusion with segmental screw fixation for validation of this technique.

Results

The novel technique allowed surgeons, from office or home, to evaluate the precise anatomy of each pedicle and the risks of screw misplacement, and to perform 3D preoperative planning for screw placement on their own computer. Looking at both 3D guidance images on a TV monitor and the bony structures of the posterior elements in each patient in the operating theater, surgeons were able to determine the best entry point for each PS with ease and confidence. Using the current technique, the screw malposition rate was 4.5% in the thoracic region in corrective surgery for AIS.

Conclusions

The authors found that 3D-VG TIPS worked on a consumer-class computer and easily visualized the ideal entry point and trajectory of PSs in any operating theater without costly special equipment. This new technique is suitable for preoperative planning and intraoperative guidance when performing reconstructive surgery with PSs.

Pediatric pedicle screws: comparative effectiveness and safety: a systematic literature review from the Scoliosis Research Society and the Pediatric Orthopaedic Society of North America task force

BACKGROUND

Pedicle screws are widely used in spinal surgery. There is extensive published literature concerning the use of pedicle screw instrumentation for spinal surgery in adults. Now there is a trend to use pedicle screws in pediatric patients, including the very young. A systematic review of the current English-language literature on the use of pedicle screw instrumentation in the pediatric age group was performed to specifically determine (1) the pedicle screw placement accuracy in patients with spine deformity and (2) the effect size of all-pedicle screw constructs compared with other methods of spinal instrumentation in terms of the percentage of scoliosis correction.

METHODS

English-language studies of pedicle screw use in pediatric patients (defined as those younger than eighteen years of age) were included. Descriptive statistics synthesized the accuracy of pedicle screw placement. Accuracy rates were compared between pediatric and adult patients. The effect of pedicle screw instrumentation on scoliosis correction was calculated with use of Cobb angle measurements.

RESULTS

On the basis of the literature search, 1181 articles were screened, 320 abstracts were examined, and ninety full-text articles representing 5761 patients were reviewed in detail. Seventeen studies met the inclusion criteria for the analysis of pedicle screw placement accuracy. A total of 13,536 pedicle screws were placed in 1353 pediatric patients. The overall placement accuracy rate in pediatric patients was 94.9%, which was higher than the rate of 91.5% reported for adults. The weighted, geometric, and 5% trimmed mean accuracy rates of pedicle screw placement were 91.9%, 88.5%, and 89.1%, respectively (standard deviation = 10%; interquartile range = 10%). Sixteen comparative studies met the inclusion criteria for the analysis of the effect of pedicle screw instrumentation on scoliosis correction. Pedicle screw constructs had a significantly larger percentage of Cobb angle correction compared with hooks (Cohen's d = 1.14) and hybrid constructs (Cohen's d = 0.49).

CONCLUSIONS

The accuracy of pedicle screw placement in the pediatric spine exceeds the accuracy rate reported in adults. Pedicle screw instrumentation constructs are significantly more effective for scoliosis correction, as determined on the basis of Cobb angle measurements, than are hook constructs and hybrid constructs.

Pedicle screw insertion accuracy with different assisted methods: a systematic review and meta-analysis of comparative studies

Studies revealed that navigation systems that provided intraoperative assistance might improve pedicle screw insertion accuracy, and also implied that different systems provided different pedicle screw insertion accuracy. A systematic review and meta-analysis was conducted to focus on the pedicle screw insertion accuracy with or without the assistance of image-guided system, and the variance among the different navigation systems. Comparative studies were searched on pedicle screw insertion accuracy between conventional and navigated method, and among different navigation systems. A total of 43 papers, including 28 clinical, 14 cadaveric and 1 model studies, were included in the current study. For clinical articles, there were 3 randomized clinical trials, 4 prospective comparative studies and 21 retrospective comparative studies. The incidence of pedicle violation among computer tomography-based navigation method group was statistically significantly less than that observed among the conventional group (OR 95% CI, in vivo: 0.32-0.60; in vitro: 0.24-0.75 P < 0.01). Two-dimensional fluoroscopy-based navigation system (OR 95% CI, in vivo: 0.27-0.48; in vitro: 0.43-0.88 P < 0.01) and three-dimension fluoroscopy-based navigation system (OR 95% CI, in vivo: 0.09-0.38; in vitro: 0.09-0.36 P < 0.01) also obtained significant reduced screw deviation rate over traditional methods. Between navigated approaches, statistically insignificant individual and pooled RR values were observed for all in vivo subgroups. Pooled estimate of in vitro studies show that computer tomography-based and three-dimension fluoroscopy-based navigation system provided more accurate pedicle screw insertion over two-dimension fluoroscopy-based navigation system. Our review showed that navigation provided a higher accuracy in the placement of pedicle screws compared with conventional methods. The superiority of navigation systems was obvious when they were applied to abnormal spinal structure. Although no strong in vivo evidence has detected significantly different pedicle screw placement accuracy among the three major navigation systems, meta-analysis revealed the variance in pedicle screw insertion accuracy with different navigation methods.

Accuracy of Image-Guided Pedicle Screw Placement Using Intraoperative Computed Tomography-Based Navigation With Automated Referencing, Part I: Cervicothoracic Spine

BACKGROUND:

Image-guided spinal instrumentation reduces the incidence of implant misplacement.

OBJECTIVE:

To assess the accuracy of intraoperative computed tomography (iCT)-based neuronavigation (iCT-N).

METHODS:

In 35 patients (age range, 18-87 years), a total of 248 pedicle screws were placed in the cervical (C1-C7) and upper and midthoracic (T1-T8) spine. An automated iCT registration sequence was used for multisegmental instrumentation, with the reference frame fixed to either a Mayfield head clamp and/or the most distal spinous process within the instrumentation. Pediculation was performed with navigated drill guides or Jamshidi cannulas. The angular deviation between navigated tool trajectory and final implant positions (evaluated on postinstrumentation iCT or postoperative CT scans) was calculated to assess the accuracy of iCT-N. Final screw positions were also graded according to established classification systems. Mean follow-up was 16.7 months.

RESULTS:

Clinically significant screw misplacement or iCT-N failure mandating conversion to conventional technique did not occur. A total of 71.4% of patients self-rated their outcome as excellent or good at 12 months; 99.3% of cervical screws were compliant with Neo classification grades 0 and 1 (grade 2, 0.7%), and neurovascular injury did not occur. In addition, 97.8% of thoracic pedicle screws were assigned grades I to III of the Heary classification, with 2.2% grade IV placement. Accuracy of iCT-N progressively deteriorated with increasing distance from the spinal reference clamp but allowed safe instrumentation of up to 10 segments.

CONCLUSION:

Image-guided spinal instrumentation using iCT-N with automated referencing allows safe, highly accurate multilevel instrumentation of the cervical and upper and midthoracic spine. In addition, iCT-N significantly reduces the need for reregistration in multilevel surgery.

Image-guided pedicle screw insertion accuracy: a meta-analysis

Improved pedicle screw insertion accuracy has been reported with the assistance of computer tomography-based navigation. Studies also indicated that fluoroscopy-based navigation offers high accuracy and is comparable to CT-based assistance. However, different population characteristics and assessment methods resulted in inconsistent conclusions. We searched OVID, Springer, and MEDLINE databases to conduct a meta-analysis of the published literature specifically looking at accuracy of pedicle screw placement with different navigation methods. Subgroups and descriptive statistics were determined based on the subject type (in vivo or cadaveric), navigational method, and spinal level. A total number of 7,533 pedicle screws were summarised in our database with 6,721 screws accurately inserted into the pedicles (89.22%). Overall, the median placement accuracy for the in vivo CT-based navigation subgroup (90.76%) was higher than that with the use of two-dimensional (2D) fluoroscopy-based navigation (85.48%). We concluded that CT-based navigation could provide a higher accuracy in the placement of pedicle screws for all subgroups presented. In the lumbar level, 2D fluoroscopy-based navigation was comparable with CT-based navigation. Discrepancy between the two navigation types increased in the thoracic level for the in vivo populations, where there was less potential in the use of 2D fluoroscopy-based navigation than CT-based navigation.