Safety Of Pedicle Screw Placement Research Articles

A Novel Intraoperative CT Navigation System for Spinal Fusion Surgery in Lumbar Degenerative Disease: Accuracy and Safety of Pedicle Screw Placement.

Background: In recent years, intraoperative computed tomography (CT) navigation has become widely used for the insertion of pedicle screws in spinal fusion surgery. However, conventional intraoperative CT navigation may be impaired by infrared interference between the infrared camera and surgical instruments, which can lead to the misplacement of pedicle screws. Recently, a novel intraoperative CT navigation system, NextAR, has been developed. It uses a small infrared camera mounted on surgical instruments within the surgical field. NextAR navigation can minimize the problem of infrared interference and be expected to improve the accuracy of pedicle screw placement. Methods: This study investigated the accuracy of pedicle screw insertion under NextAR navigation in spinal fusion surgery for lumbar degenerative diseases. The accuracy of pedicle screw placement was evaluated in 15 consecutive patients using a CT grading scale. Results: Screw perforation occurred in only 1 of the total 70 screws (1.4%). Specifically, there was one grade 1 perforation within 2 mm, but no perforations larger than 2 mm. There were no reoperations or neurological complications due to screw misplacement. Conclusions: NextAR navigation can provide high accuracy for pedicle screw insertion and help ensure safe spinal fusion surgery for lumbar degenerative diseases.

Spine Surgery with Electronic Conductivity Device: A Prospectively Multicenter Randomized Clinical Trial and Literature Review.

Improving accuracy and safety of pedicle screw placement is of great clinical importance. Electronic conductivity device (ECD) can be a promising technique with features of affordability, portability, and real-time detection capabilities. This study aimed to validate the safety and effectiveness of a modified ECD. The ECD underwent a modification where six lamps of various colors, and it was utilized in a prospectively multicenter randomized controlled clinical trial involving 96 patients across three hospitals from June 2018 to December 2018. The trial incorporated a self-control randomization with an equal distribution of left or right side of vertebral pedicle among two groups: the free-hand group and the ECD group. A total of 496 pedicle screws were inserted, with 248 inserted in each group. The primary outcomes focused on the accuracy of pedicle screw placement and the frequency of intraoperative X-rays. Meanwhile, the secondary indicator measured the time required for pedicle screw placement. Results were presented as means ± SD. Paired samples t-test and χ2 -test were used for comparison. Furthermore, an updated review was conducted, which included studies published from 2006 onwards. Baseline patient characteristics were recorded. The primary accuracy outcome revealed a 96.77% accuracy rate in the ECD group, compared to a 95.16% accuracy rate in the free-hand group, with no significant differences noted. In contrast, ECD demonstrated a significant reduction in radiation exposure frequency when compared to the free-hand group (1.11 ± 0.32 vs. 1.30 ± 0.53; p < 0.001), resulting in a 14.6% reduction. Moreover, ECD displayed a decrease of 30.38% in insertion time (70.88 ± 30.51 vs. 101.82 ± 54.00 s; p < 0.001). According to the results of the 21 studies, ECD has been utilized in various areas of the spine such as the atlas, thoracic and lumbar spine, as well as sacral 2-alar-iliac. The accuracy of ECD ranged from 85% to 100%. The prospectively randomized trial and the review indicate that the use of ECD presents a secure and precise approach to the placement of pedicle screws, with the added benefit of reducing both procedure time and radiation exposure.

Performance evaluation of an AI-based preoperative planning software application for automatic selection of pedicle screws based on computed tomography images.

Recent neurosurgical applications based on artificial intelligence (AI) have demonstrated its potential in surgical planning and anatomical measurement. We aimed to evaluate the performance of an AI planning software application on screw length/diameter selection and insertion accuracy in comparison with freehand surgery. A total of 45 patients with 208 pedicle screw placements on thoracolumbar segments were included in this analysis. The novel AI planning software was developed based on a deep learning model. AI-based pedicle screw placements were selected on the basis of preoperative computed tomography (CT) data, and freehand surgery screw placements were observed based on postoperative CT data. The performance of AI pedicle screw placements was evaluated on the components of screw length, diameter, and Gertzbein grade in comparison with the results achieved by freehand surgery. Among 208 pedicle screw placements, the average screw length/diameters selected by the AI model and used in freehand surgery were 48.65 ± 5.99 mm/7.39 ± 0.42 mm and 44.78 ± 2.99 mm/6.1 ± 0.27 mm, respectively. Among AI screw placements, 85.1% were classified as Gertzbein Grade A (no cortical pedicle breach); among free-hand surgery placements, 64.9% were classified as Gertzbein Grade A. The novel AI planning software application could provide an accessible and safe pedicle screw placement strategy in comparison with traditional freehand pedicle screw placement strategies. The choices of pedicle screw dimensional parameters made by the model, including length and diameter, may provide potential inspiration for real clinical discretion.

Modified pedicle screw fixation under guidance of stress analysis for cervicothoracic junction: Surgical technique and outcomes.

In cervicothoracic junction, the use of strong fixation device such as pedicle screw placement is often needed. The current study aimed to evaluate the accuracy and safety of pedicle screw placement using stress conduction analysis in the clinical application. We retrospectively collected patients who underwent pedicle screw internal fixation in cervicothoracic junction. Patients were divided into conventional nail placement (Group A) and modified pedicle screw implantation under guidance of stress analysis (Group B) according to the methods of pedicle screw placement. The accuracy of pedicle screw placement was assessed by computed tomography (CT) examination, and the success rate was calculated. A total of 80 patients who underwent pedicle screw internal fixation in cervicothoracic junction were included. There were no obvious differences in baseline characteristics between two groups. The success rate of total screw placement, cervical spine screw placement and upper thoracic spine screw placement in Group B was higher than those in Group A (P< 0.001, P= 0.005, P= 0.008). Additionally, Heary Grade I in the Group B was higher than Group A (P= 0.001). Stress analysis-guided technique can increase the accuracy of pedicle screw placement. Importantly, it meets the requirements of internal fixation of the cervicothoracic junction.

Accuracy and Safety of Pedicle Screw Placement for Treating Adolescent Idiopathic Scoliosis: A Narrative Review Comparing Available Techniques.

Posterior spinal fusion and segmental spinal instrumentation using pedicle screws (PS) is the most used procedure to correct adolescent idiopathic scoliosis. Computed navigation, robotic navigation, and patient-specific drill templates are available, besides the first described free-hand technique. None of these techniques are recognized as the gold standard. This review compares the PS placement accuracy and misplacement-related complication rates achieved with the techniques mentioned above. It further reports PS accuracy classifications and anatomic PS misplacement risk factors. The literature suggests a higher PS placement accuracy for robotic relative to computed navigation and for the latter relative to the free-hand technique (misplacement rates: 0.4-7.2% versus 1.9-11% versus 1.5-50.7%) using variable accuracy classifications. The reported PS-misplacement-related complication rates are, however, uniformly low (0-1.4%) for every technique, while robotic and computed navigation induce a roughly fourfold increase in the patient's intraoperative radiation exposure relative to the free-hand technique with fluoroscopic implant positioning control. The authors, therefore, recommend dedicating robotic and computed navigation for complex deformities or revisions with altered landmarks, underline the need for a generally accepted PS accuracy classification, and advise against PS placement in grade 4 pedicles yielding higher misplacement rates (22.2-31.5%).

Using a 3D Navigation Template to Increase the Accuracy of Thoracic Pedicle Screws in Patients with Scoliosis.

This study compares the accuracy and safety of pedicle screw placement using a 3D navigation template with the free-hand fluoroscopy technique in scoliotic patients. Fifteen scoliotic patients were recruited and divided into a template group (eight cases) and a free-hand group (seven cases). All patients received posterior corrective surgeries, and the pedicle screw was placed using a 3D navigation template or a free-hand technique. After surgery, the positions of the pedicle screws were evaluated using CT. A total of 264 pedicle screws were implanted in 15 patients. Both the two techniques were found to achieve satisfactory safety of screw insertion in scoliotic patients (89.9% vs. 90.5%). In the thoracic region, the 3D navigation template was able to achieve a much higher accuracy of screw than the free-hand technique (75.3% vs. 60.4%). In the two groups, the accuracy rates on the convex side were slightly higher than on the concave side, while no significance was seen. In terms of rotational vertebrae, no significant differences were seen in Grades I or II vertebrae between the two groups. In conclusion, the 3D navigation template technique significantly increased the accuracy of thoracic pedicle screw placement, which held great potential for extensively clinical application.

The Accuracy and Safety of a Pedicle Screw Using the Freehand Technique in Minimally Invasive Scoliosis Surgery.

The safety and clinical usefulness of minimally invasive scoliosis surgery (MISS) has been reported in various studies. However, freehand pedicle screwing in MISS remains technically challenging. The purpose of this study is to evaluate the accuracy and safety of pedicle screw placement using the freehand technique in adolescent idiopathic scoliosis (AIS) patients treated with MISS compared to conventional open scoliosis surgery (COSS). We included 76 patients who underwent deformity correction for AIS. Computed tomography scans were used to assess screw violations divided into 2 groups according to the surgical technique: MISS or COSS. Anterior violations were classified into grade 0, 1 (no contact with internal organs), and 2 (contact with internal organs). Medial and lateral violations were classified into grade 0, 1 ( < 2 mm), and 3 ( ≥ 2 mm). grade 2 were considered critical violations. A total of 630 and 1,174 pedicle screws were inserted in the MISS and COSS groups, respectively. The overall critical violation rates of the MISS and COSS groups were 16.8% (106 screws) and 14.0% (165 screws) (p = 0.116). Medial critical violations on the left side in the middle thoracic region frequently occurred in the MISS group compared to the COSS group (p = 0.003). There were no statistical differences in the complications. Pedicle screw placement using the freehand technique in MISS for AIS patients provided similar accuracy and safety compared to COSS. Pedicle screws inserted on the left side of the middle thoracic region, exhibited more medial critical violations in the MISS group.

Comparison of 3D-printed Navigation Template-assisted Pedicle Screws versus Freehand Screws for Scoliosis in Children and Adolescents: A Systematic Review and Meta-analysis.

There is a lack of attention to screw placement techniques for surgical treatment of scoliosis in children and adolescents. This meta-analysis aims to compare the accuracy and safety of pedicle screw placement between the 3D-printed navigation template technique and the freehand technique during corrective surgery for scoliosis in children and adolescents. A comprehensive search was conducted for relevant articles up to December 2021 in databases including PubMed, Embase, MEDLINE, Cochrane, and Web of Science. The systematic meta-analysis compared the efficacy of pedicle screw placement between the two techniques, including accuracy of pedicle screw placement, complication rate, operation time, blood loss, mean placement time per screw, and mean times for fluoroscopy. The seven articles analyzed in this study involved 229 patients altogether. A total of 2,805 pedicle screws were placed by the two methods. Our results revealed that the 3D-printed guide template technique was more accurate than the freehand technique in pedicle screw placement (odds ratio [OR] =2.96; 95% confidence interval [CI]: 2.24-3.91; p < 0.000) with a lower complication rate (OR = 0.21; 95% CI: 0.06-0.78; p = 0.02). The operation time (mean difference [MD] = -34.37; 95% CI: -67.47 to -1.28; p = 0.04) and mean placement time per screw (MD = -3.11; 95% CI: -6.13 to -0.09; p = 0.04) and mean times for fluoroscopy (MD = -6.60; 95% CI: -8.66 to -4.55; p < 0.000) significantly decreased among patients in the 3D-printed navigation template group compared with those in the freehand technique group. In addition, the two techniques had no significant statistical difference in blood loss. Compared with the traditional freehand technique, the 3D-printed guide template is a promising technique with higher accuracy and safety in screw placement for surgical treatment of scoliosis in children and adolescents, and is worth popularizing and validating through more prospective clinical studies.

Robotic-assisted spine surgery allows for increased pedicle screw sizes while still improving safety as indicated by elevated triggered electromyographic thresholds

The present study used triggered electromyographic (EMG) testing as a tool to determine the safety of pedicle screw placement. In this Institutional Review Board exempt review, data from 151 consecutive patients (100 robotic; 51 non-robotic) who had undergone instrumented spinal fusion surgery of the thoracic, lumbar, or sacral regions were analyzed. The sizes of implanted pedicle screws and EMG threshold data were compared between screws that were placed immediately before and after adoption of the robotic technique. The robotic group had significantly larger screws inserted that were wider (7 ± 0.7 vs 6.5 ± 0.3 mm; p < 0.001) and longer (47.8 ± 6.4 vs 45.7 ± 4.3 mm; p < 0.001). The robotic group also had significantly higher stimulation thresholds (34.0 ± 11.9 vs 30.2 ± 9.8 mA; p = 0.002) of the inserted screws. The robotic group stayed in the hospital postoperatively for fewer days (2.3 ± 1.2 vs 2.9 ± 2 days; p = 0.04), but had longer surgery times (174 ± 37.8 vs 146 ± 41.5 min; p < 0.001). This study demonstrated that the use of navigated, robot-assisted surgery allowed for placement of larger pedicle screws without compromising safety, as determined by pedicle screw stimulation thresholds. Future studies should investigate whether these effects become even stronger in a later cohort after surgeons have more experience with the robotic technique. It should also be evaluated whether the larger screw sizes allowed by the robotic technology actually translate into improved long-term clinical outcomes.

Double Sublaminal Band Passage Technique for Spinal Deformity Correction.

Sublaminar band fixation is a reliable way to anchor spinal rods to the vertebral column. This technique is especially useful when the anatomy precludes safe pedicle screw placement. Sublaminar bands allow for deformity correction and stabilization of the spine. One of the disadvantages of using the sublaminar band technique is the risk for neurologic injury during the passage of the band between the dura and lamina. In this article, we describe a new technique for passing sublaminar bands, i.e., the double sublaminar band passage technique. This technique decreases the number of passes against the dura, thereby decreasing the opportunity for neural injury. In addition, we present an illustrative case of an 11-year-old female with neuromuscular scoliosis who underwent a posterior spinal instrumented fusion with a hybrid screw and sublaminar band construct.

Accuracy and safety of robot assisted pedicle screw placement

To investigate the accuracy and safety of pedicle screw placement assisted by orthopedic robot and C-arm fluoroscopy. The clinical data of 36 patients with spinal diseases underwent surgical treatment from January 2019 to August 2020 was retrospectively analyzed. Among them, 18 cases were implanted pedicle screws assisted by orthopaedic robot(observation group), including 12 males and 6 females, aged from 16 to 61 years with an average of (38.44±3.60) years;there were 1 case of adolescent scoliosis, 1 case of spinal tuberculosis, 7 cases of lumbar spondylolisthesis, 4 cases of thoracic fracture and 5 cases of lumbar fracture. Another 18 cases were implanted pedicle screws assisted by C-arm fluoroscopy(control group), including 10 males and 8 females, aged from 18 to 58 years with an average of (43.22±2.53) years;there were 1 case of adolescent scoliosis, 6 cases of lumbar spondylolisthesis, 6 cases of thoracic fracture and 5 cases of lumbar fracture. The intraoperative fluoroscopy times, nail placement time and postoperative complications were recorded in two groups. CT scan was performed after operation. The Gertzbein-Robbins standard was used to evaluate the accuracy of pedicle screw placement which was calculated. The number of intraoperative fluoroscopy in observation group was(6.89±0.20) times, which was significantly higher than that in control group(14.00±0.18)times(P<0.05). The placement time of each screw in observation group was(2.56±0.12) min, which was significantly different from that in control group(4.22±0.17) min (P<0.05). One case of incision infection occurred in control group after operation, and recovered after active dressing change. During the follow-up period, no serious complications such as screw loosening and fracture occurred in two groups, and there was no significant difference in complications between two groups(P>0.05). A total of 107 screws were placed in observation group, including 101 screws in class A, 4 in class B, 2 in class C, 0 in class D and 0 in class E, the accuracy rate of pedicle screw placement=[(number of screws in class A+B) / the number of all screws placed in the group] ×100%=98.1%(105/107); and a total of 104 screws were placed in control group, including 90 screws in class A, 4 in class B, 5 in class C, 5 in class D and 0 in class E, the accuracy rate of pedicle screw implantation=[(number of screws in class A+B/the number of all screws placed in the group]×100%=90.3% (94/104); there was significant difference between two groups (P<0.05). Orthopaedic robot assisted pedicle screw placement has the advantages of less fluoroscopy times, shorter screw placement time and higher accuracy, which can further improve the surgical safety and has a broad application prospect in the orthopaedic.

Improved Accuracy and Safety of Pedicle Screw Placement by Using a Probe with an Electrical Conductivity-Measuring Device during Severe Syndromic and Neuromuscular Scoliosis Spine Surgery.

An electrical conductivity-measuring device (ECD) has recently been developed to support pedicle screw placement. However, no evidence exists regarding its efficacy for syndromic/neuromuscular scoliosis with extremely difficult screwing. We retrospectively reviewed 2010–2016 medical records of 21 consecutive syndromic/neuromuscular scoliosis patients undergoing free-hand segmental fixation surgery at our institution and compared the pedicle screw insertion accuracy and safety between 10 with a conventional non-ECD probe (2010–2013) and 11 with an ECD probe (2014–2016). We analyzed preoperative pedicle shape and postoperative screw placement in computed tomography. There were no significant differences between ECD and non-ECD groups in demographic, clinical, and treatment characteristics including scoliosis severity and pedicle diameter. The abandonment rate due to liquorrhea or perforation was lower in ECD (12.3%) than in non-ECD (26.7%) (p < 0.01). Acceptable insertion without perforation or <2-mm lateral/cranial position was more frequent in ECD (67.1%) than in non-ECD (56.9%) (p = 0.02). Critical ≥5-mm medial/caudal malposition was not seen in ECD (0.0%) but in non-ECD (2.4%) (p = 0.02). The perforation distance was shorter in ECD (2.2 ± 1.1 mm) than in non-ECD (2.6 ± 1.7 mm) (p = 0.01). Results involve small sample size, selection, performance, and learning curve biases; nevertheless, ECD could be useful for more accurate and safer pedicle screw placement in severe syndromic/neuromuscular scoliosis.

3D printed templates improve the accuracy and safety of pedicle screw placement in the treatment of pediatric congenital scoliosis

BackgroundThree-dimensional (3-D) printed guidance templates are being increasingly used in spine surgery. The purpose of this study was to determine if 3D printed navigation templates can improve the accuracy of pedicle screw placement and decrease the complication rate compared to freehand screw placement in the treatment of children with congenital scoliosis.MethodsThe records of pediatric patients with congenital scoliosis treated at our hospital from January 2017 to January 2019 were retrospectively reviewed. Patients were divided into those where a 3D printed guidance templated was used and those in which the freehand method was used for pedicle screw placement. The accuracy rate of pedicle screw placement, surgical outcomes, and complications were compared between groups.ResultsA total of 67 children with congenital scoliosis were included (43 males and 24 females; mean age of 4.13 ± 2.66 years; range, 2–15 years). There were 34 children in the template-assisted group and 33 in the freehand group. The excellent accuracy rate of pedicle screw placement was significantly higher in the template-assisted group (96.10% vs. 88.64%, P = 0.007). The main Cobb angle and kyphosis angle were similar between the 2 groups preoperatively and postoperatively (all, P > 0.05), and in both groups both angles were significantly decreased after surgery as compared to the preoperative values (all, P < 0.001). The degree of change of the Cobb angle of the main curve and kyphosis angle were not significantly different between the 2 groups. There were no postoperative complications in the template group and 4 in the freehand group (0% vs. 12.12%; P = 0.009). All 4 patients with complications required revision surgery.

Demographic Analysis of Pedicle Diameter, and Estimated Pedicle Screw Length of the Lumbar Spine in a Diverse Population.

Recent literature confirms the importance of understanding the variability in pedicle morphology among races. These studies suggest that more detailed and reliable measurements of pedicles should be undertaken. However, there is limited data on average pedicle diameters (PDs) or estimated pedicle screw lengths (EPSLs) between diverse racial populations. We sought to determine the differences in PD and EPSL in the lumbar spine between various races: "Asian," "Black," "White," and "Hispanic" to aid in perioperative planning during instrumented spinal fusion. Axial cuts of 404 patients were inspected to obtain their transverse outer cortical PD as measured through the isthmus, and EPSL by measuring the posterior entry point at the longest distance, which perpendicularly transected the measured isthmic diameter, to the anterior vertebral cortex from L1 to L5. We examined the average PD and PD range at each level for each race. To determine the significance, we used a mixed analysis of variance and a post hoc analysis. In this retrospective chart review the races were found to be significantly different in PD and EPSL (P < .001). Post hoc analysis using Dunn-Bonferroni correction showed that Asians had significantly smaller PDs than Blacks and Whites (P < .002 and P < .014, respectively). The White and Hispanic population had significantly longer EPSLs when compared to Blacks and Asians from L1 to L5 (P < .01). This study demonstrates that there are significant differences in pedicle morphology among races that must be taken into consideration when inserting pedicle screws during lumbar spinal fusion. Knowledge of these differences is of the utmost importance in order to limit complications while improving fixation. 3. Pedicle morphology is variable between races and understanding these differences is important for the safe placement of pedicle screws.

Lumbar Pedicle Morphology and Vertebral Dimensions in Isthmic and Degenerative Spondylolisthesis-A Comparative Study.

The pedicle screw is the most common device used to achieve fixation in fusion of spondylolistheses. Safe and accurate placement with this technique relies on a thorough understanding of the bony anatomy. There is a paucity of literature comparing the surgically relevant osseous anatomy in patients with a degenerative spondylolisthesis (DS) and an isthmic spondylolisthesis (IS). The goal of this study was to determine the differences in the osseous anatomy in patients with a DS and those with an IS. A retrospective comparative cohort study was conducted on patients with a single-level, symptomatic L4-L5 DS or a single-level, symptomatic L5-S1 IS. Magnetic resonance imaging for these patients was reviewed. Morphometries of the pedicle and vertebral body were analyzed by 2 independent observers for the levels from L3 to S1, and radiographic parameters were compared between groups. A total of 572 levels in 143 patients were studied, including 103 patients with a DS and 40 with an IS. After accounting for confounders, IS and DS had an independent effect on transverse vertebral body width, pedicle height and width, and sagittal pedicle angle. Patients with an IS had a smaller pedicle height (P < .001) and pedicle width (P = .001) than patients with DS. In addition, the angulation of the pedicles varied on the basis of the diagnosis. The osseous anatomy is significantly different in patients with a DS than with an IS. Patients with an IS have smaller pedicles in the lumbar spine. Also, the L4 and L5 pedicles are more caudally angulated and the S1 pedicle is less medialized. 3. Understanding the differences in pedicle anatomy is important for the safe placement of pedicle screws.

Accuracy of Placement of Pedicle Screws in the Lumbosacral Region of Dogs Using 3D-Printed Patient-Specific Drill Guides.

The aim of this study was to report the accuracy of pedicle screw placement using three-dimensional (3D)-printed, patient-specific drill guides in the lumbosacral region of dogs. This was a retrospective study. Thirty-two pedicle screws were placed in five dogs. Medical records were reviewed between November 2015 and November 2018 for dogs showing clinical signs associated with cauda equina syndrome. Inclusion criteria included preoperative magnetic resonance imaging, pre- and postoperative computed tomography (CT) and dorsal stabilization, with pedicle screws placed using 3D-printed, patient-specific drill guides and polymethylmethacrylate. Screw placement was evaluated for medial or lateral breaching on postoperative CT. Five dogs met the inclusion criteria. Four had degenerative lumbosacral stenosis and one had discospondylitis. All dogs had failed medical management prior to surgery. Of 32 bicortical pedicle screws placed, 30 were fully contained inside the pedicle and 2 were partially breaching the vertebral canal (less than one-third of the screw diameter). Postoperative CT revealed good alignment of L7-S1 in all planes. This technique enabled an accurate and safe placement of pedicle screws in the lumbosacral region of dogs with lumbosacral disease. Three-dimensional, printed patient-specific drill guides are a safe and effective method of placing pedicle screws in dogs with lumbosacral disease.

Anatomical study on the feasibility of a new self-guided pedicle tap

To evaluate the accuracy and safety of pedicle screw placement using a new self-guided pedicle tap. According to the anatomical characteristics of the pedicle, a new self-guided pedicle tap was developed. Six adult spinal specimens including 4 males and 2 females were selected and tapped thread on the right and left sides of each pair of pedicles from the same segment T1 to L5 with traditional taps (control group) and new self-guided pedicle taps (experimental group), respectively. And the pedicle screws were placed. The screwing time was recorded and compared between two groups. CT scanning was completed to observe the accuracy and safety of the screw placement according to the Heary classification of imaging results. The screwing time of thoracic and lumbar vertebrae in the experimental group were (5.87±1.25) min and(5.45±1.67) min, respectively. While those in the control group were (6.12±1.69) min and (6.22±2.13) min, respectively. Then there was no significant difference in screwing time of thoracic and lumbar vertebrae between two groups (P>0.05). The Heary grade of the pedicle screw showed that Heary gradeⅠand Heary gradeⅠ+Ⅱwere respectively 86 (84.31%) and 96 (94.12%) in the experimental group, 72 (71.29%) and 84 (83.17%) in control group, and the difference between two groups was statistically significant (P<0.05). The new self-guided pedicle tap can accurately and safely insert the thoracolumbar pedicle screw, with low cost, easy operation, and good clinical application value.

Comparison of the Accuracy and Safety of Pedicle Screw Placement in Thoracic Spine Between 3D Printed Navigation Templates and Free Hand Technique

Relevance. Transpedicular spine fixation is considered the gold standard for posterior stabilization of the spine in various pathological processes. The most common implantation technique is the free hand method. But today the implantation with 3D printed individual navigation templates is gaining popularity. Purpose — to compare results of the pedicle screw placement in thoracic spine with application of 3D printed navigation templates by various design and free hand technique. Materials and Methods. Results of the three group of patients were analyzed based on postoperative CT. In group 1 (free hand) 112 screws were placed to 23 patients. In group 42 screws were placed to 11 patients using bilateral monosegmental navigation templates, in group 3 (13 patients, 42 screws) — using bilateral monosegmental templates with additional support on the spinous process. The safety of implantation was assessed and compared in all groups. In groups 2 and 3 the accuracy was also evaluated based on the difference between the planned and actual screws trajectory. Results. In group 1 safety grade 0 was registered in 66,96%, safety grade 1 in 18,75%, safety grade 2 — in 9,82%, safety grade 3 — in 4,46%. In group 2 grade 0 was registered in 85,71%, safety grade 1 — in 14,29%. In group 3 grade 0 — in 90,74%, safety grade 1 — in 9,26%. There were no cases of the cortical bone perforation for more than the half of the screw diameter in groups 2 and 3. The differences in the safety parameters are significant between free hand and both groups with application of the navigation templates. Assessment of the deviation hasn’t revealed significant difference depending on the type of the templates. Conclusion. The use of the individual navigation templates for pedicular screws implantation in the thoracic spine is safer than the free hand method (p0.05). Single-level bilateral matrices made by FDM technology from polylactide with support on a part of the dorsal vertebral structures make it possible to achieve the high implantation accuracy. Additional support on the spinous process does not lead to a statistically significant improvement in accuracy and safety indicators (p0.05), while requiring extended dissection and resection of the ligamentous elements.

End Vertebra Versus Apical Vertebra: Where Are We More Likely to Misplace in Spine Deformity?

Pedicle screws placement remains technically demanding. The thoracic curve apex is considerably difficult due to its unique morphology and severe rotation. In comparison the upper end vertebrae have smaller pedicles and limited soft tissue exposure. This study seeks to evaluate the likelihood of screw misplacement at the end vertebra and apex. A retrospective review of preoperative and postoperative computed tomographic (CT) scans of spinal deformity patients who underwent posterior spinal fusion with pedicle screw constructs between 2004 and 2011 was performed. Pedicles located at the upper instrumented vertebra (UIV) and lower instrumented vertebra (LIV), and the major and minor apices were evaluated. Pedicle morphology was studied on preoperative CT and screw placement on postoperative CT. In total, 188 patients met the inclusion criteria, 172 had preoperative CT scans and 133 had postoperative CT scans. The UIV had a significantly lower percentage of normal pedicles (type A) compared with apex major, apex minor, or LIV (59.1% vs. 76.1% vs. 77.3% vs. 98.7%; P<0.001). UIV had significantly the lowest percentage of normal normally placed screws compared with LIV, apex major, or apex minor (69.4% vs. 97.3% vs. 87.6% vs. 92.1%; P<0.001). In a logistic regression adjusted for preoperative Cobb angles, UIV was more likely to have screws misplaced (odds ratio =7.56; 95% confidence interval, 4.01-14.30; P<0.001) and abnormal pedicles (odds ratio=2.81; 95% confidence interval, 1.52-5.19; P=0.001) compared with any other location studied. In abnormal pedicles, 41 (39.8%) of the 103 UIV screws were misplaced, whereas 10 (16.4%) of the 61 apex major, apex minor, or LIV screws were misplaced (P=0.007). The UIV presents more of a risk for pedicle screw misplacement and abnormal morphology when compared with LIV and apical vertebra. We believe these findings can aid in the surgeon's preoperative and intraoperative management to ensure increased success in accurate and safe pedicle screw placement. Level III.

Accuracy and reliability of spinal navigation: An analysis of over 1000 pedicle screws

PurposeTo estimate the rate of pedicle screw malpositioning associated with placing pedicle screws using intraoperative computed tomography (CT)-guided spinal navigation. MethodsWe analysed the records of 219 patients who underwent pedicle screw fixation using O-arm-based navigation. Screw placement accuracy was evaluated on intraoperative CT scans acquired after pedicle screw insertion. Breaches were graded according to the Gertzbein classification (grade 0–III). ResultsOf 1152 pedicle screws included, 47 had pedicle violations noted on intraoperative CT. Pedicle screw violation was noted for 17 of 241 screws placed in the cervical spine (overall breach rate, 7.05%; 3.73% and 3.3% with grade I and II, respectively), for 11 of 300 screws placed in the thoracic spine (overall breach rate, 3.67%; 2%, 1%, and 0.67% with grade I, II, and III, respectively), and for 22 of 611 screws placed in the lumbar spine (overall breach rate, 3.6%; 2.29% and 0.82% with grade I and II, respectively). The rate of accuracy of pedicle screw fixation was 93%, 96.33%, and 96.4% for the cervical, thoracic, and lumbar spine, respectively. ConclusionsUsing O-arm-based intra-operative three-dimensional scans for navigation can improve the reliability, accuracy, and safety of pedicle screw placement, reducing the risk for reoperation and hospitalization due to implant-related complications. Further improvement may be achieved by adequate consideration of potential sources of errors.