Method Of Screw Insertion Research Articles

Relationship Between Laterality of Orthodontic Miniscrew Failure and Clinical Variables

Background/Objectives: Many reports on orthodontic miniscrew insertion focus on insertion conditions, such as technique, but not on the insertion environment, such as the operator’s dominant hand. This study aimed to ascertain whether the operator’s dominant hand affects laterality in the success rate of manual and motorized miniscrew insertion methods. Methods: This study retrospectively investigated the medical records of 250 Japanese patients, aged ≥15 years, who underwent miniscrew implantation in the maxilla by right-handed operators with at least 3 years of experience. A cross-tabulation analysis, Chi-square test, and multiple logistic regression analysis were performed to compare the success rates of the two insertion methods. Results: A total of 454 screws were implanted (346 manual and 108 motorized), with an overall success rate of 79.2%. No significant difference was observed in the success rate between the manual (77.7%) and motorized groups (84.2%). Regarding the laterality of the overall success rate, the right-side success rate (84.1%) was significantly higher than that of the left side (75.6%). The right-side success rate in the manual group (82.7%) was significantly higher than that of the left-side (73.0%). In the motorized group, no significant difference was observed between the success rate of insertion on the right (84.6%) and left sides (83.9%). Multiple regression analysis showed that the miniscrew insertion stability was influenced by the insertion side and the operator’s years of experience. Conclusions: The manual screw insertion method was susceptible to environmental factors and less successful in left-side insertion by right-handed operators.

O-arm navigation without apnoea in thoracolumbar and lumbar spine surgery: Outcomes and considerations in a prospective study

BackgroundIntra operative three dimensional navigation-assisted pedicle screw insertion typically requires apnoea for reliable image production. However this carries potential risks to the physiologically compromised patients such as patients having COPD, obesity, cardiac illnesses, and anaemia. In such patients’ safe apnoea time may be as low as 1 min, and can cause life threatening complications. Therefore, this study was done to evaluate the accuracy of thoracolumbar and lumbar pedicle screw insertion using O-arm without using apnoea during imaging, to prevent such possible complications. MethodsThis is a single centre prospective study of 238 patients treated with pedicle screw implantation under O-arm guidance, without using apnoea while imaging. The pedicle breach rate during screw insertion was graded on Gertzbein classification. Also, two senior spine surgeons independently evaluated motion artifacts in the intra operative images and rated them as ‘Significant’ or ‘Non-Significant’ for the procedure. Values of p < 0.05 were considered statistically significant. ResultsDespite not using apnoea in 238 patients with 1120 screws, there were nil screw related complications. Only in one paediatric case of dorsal spine deformity, there were blurred and inaccurate images because of chest expansion, without apnoea. Hence he was given apnoea to render the image reliable for pedicle screw insertion. The screw placement in the pedicles was checked intraoperatively and graded for breach. Grade 2 breach were seen in only 2 cases (n = 3 screws) which were revised intra operatively. The interobserver agreement on motion artifacts was good (κ = 0.565, p < 0.001). ConclusionsThe results of pedicular screw insertion performed without induced apnea are comparable to those achieved with apnea when using O-arm imaging. This technique has proven to be a safe and reliable method for pedicle screw insertion in the thoracolumbar and lumbar spine, potentially mitigating physiological complications. Nonetheless, even minor motion artifacts, on the order of a few millimeters, can significantly impact outcomes in the cervical and upper thoracic spine. Therefore, further research is warranted to evaluate the efficacy and safety of this approach in these regions of the spine.

3D printing navigation template assisted pedicle screw placement for the treatment of typeⅡold odontoid fractures

To compare the safety and clinical efficacy of freehand and 3D printing navigation template assisted screw placement in patients with old odontoid fractures of typeⅡ. Total of 38 patients with old odontoid fractures of typeⅡwere treated from November 2018 to December 2022, all of which presented as chronic neck pain. According to the different methods of screw insertion into the pedicle, the patients were divided into a navigation template group and a freehand group. In the navigation template group, there were 17 patients including 9 males and 8 females with an average age of (51.30±13.20) years old, disease duration was (22.18±7.59) months. In the freehand group, there 21 patients including 7 males and 14 females with an average age of (49.46±11.92) years old, disease duration was (19.52±9.17) months. The intraoperative blood loss, operation time, and postoperative drainage output were recorded and compared between two groups. The accuracy of screw placement was evaluated by CT scan. Before operation and 1 year after operation, cervical pain was assessed by visual analogue scale(VAS), neurological changes were evaluated by the Japanese Orthopaedic Association (JOA) score, and the degree of spinal cord injury was assessed by the American Spinal Injury Association (ASIA) injury scale. All patients were followed up for (25.31±1.21) months. The operation time of template group (112.00±20.48) min had significantly shorter than that of the freehand group(124.29±15.24) min(P<0.05), while there were no significant differences between two groups in terms of intraoperative blood loss, postoperative drainage, and hospital stay(P>0.05). At 1 year after operation, in template group and freehand group, the VAS [(2.88±0.86), (2.90±0.83)] and JOA [(14.94±1.82), (14.62±2.19)] improved with preoperative [VAS(4.71±0.92), (4.86±0.79) and JOA (12.18±2.30), (11.95±2.31)](P<0.05), with no significant difference between two groups (P>0.05). No significant improvement was observed in ASIA grading in either group at 1 year after operation(P>0.05), and there was no significant difference between two groups(P>0.05). The template group had significantly better accuracy of screw placement in the pedicle of the axis than the freehand group (P<0.05), while no significant difference was observed between two groups in the accuracy of screw placement in the pedicle of the atlas (P>0.05). In the treatment of typeⅡold odontoid fractures with posterior pedicle screw fixation, 3D printing navigation template screw placement can significantly shorten the operation time, achieve similar clinical efficacy as free-hand screw placement, and significantly improve the accuracy of screw placement in the pedicle of the axis.

Percutaneous Sacroiliac Screw Fixation: A Modified Screw Insertion Method Using Just 2 Fluoroscopy Views.

Percutaneous sacroiliac screw fixation (PSSF) is a well-defined method of surgery to fix unstable fractures of the pelvic ring with fewer post-surgical complications. However, the complex anatomy of the mentioned area makes PSSF a formidable challenge. The present study aimed to investigate a modified screw insertion method using two views of fluoroscopy X-ray instead of the prior three views to reduce the duration of operations and radiation exposures. The present study was performed on 10 radiopaque plastic pelvic models (including 20 half pelvis) during simulated surgical procedures. Of the 20 screws, 10 were inserted using the conventional method with the navigation of three fluoroscopy views (Group A). The remaining 10 were inserted using the modified method with the navigation of two fluoroscopy views, including just the outlet and inlet views, without taking the lateral view, based on our theory and order of fluoroscopy (Group B). Following screw insertion, the accuracy of screw locations was evaluated using a computed tomography (CT) scan, and the duration of operations and radiation exposures were compared between the two surgery methods at the end of the study. In both groups, nine screws (90%) were located correctly, and one screw (10%) perforated the anterior wall of the first sacral vertebra. The mean±SD of the duration of radiation exposure in groups A and B was 6.1±1.0 min and 4.2±0.1 min, respectively (P=0.01). Moreover, the mean±SD of operation duration in group A was 45.7±5.8 min, but this value in group B was 35.5±4.5, which showed a significant decrease in operation duration (P=0.04).). PSSF using a modified screw insertion method with just two fluoroscopy views not only had similar accuracy to conventional methods but also could decrease operation time and the following radiation exposure.

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

BackgroundThe 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. MethodsThe 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. ResultsThe 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. ConclusionAlthough 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%).

Pedicle morphometry analysis of main thoracic apex adolescent idiopathic scoliosis

IntroductionScrew insertion during scoliosis surgery uses free-hand pedicle screw insertion methods. However, there is a wide variation in pedicle shapes, sizes, and morphometry, especially in scoliosis patients. CT scan pedicle measurements in main thoracic Lenke type 1 adolescent idiopathic scoliosis can help visualize this diversity. This study aimed to highlight the features of pedicle morphometry on the concave and convex sides, including pedicle diameter (width in axial and height in the sagittal plane), the depth to the anterior cortex, and Watanabe Pedicle classification in patients with main thoracic apex adolescent idiopathic scoliosis.Materials and methodsThis study was a cross-sectional observational study of Adolescent Idiopathic Scoliosis (AIS) patients whose apex in the main thoracic patient underwent deformity correction procedures. We used a three-dimensional CT scan to evaluate pedicle morphometry on the apex vertebrae, three consecutive vertebrae above and below the apex.ResultsA total of 6 patients with apex main thoracic AIS with 84 pedicles consisting of 42 pedicles from each concave and convex curve were analyzed. All of the samples were female, with the mean age at the procedure being 21.2 ± 5.56. The mean cobb angle was 62° ± 23°, with the main apex between VT8-VT10. The size of the pedicle was bigger from upper to lower vertebrae. The mean pedicle depth, pedicle width, and pedicle height for the concave side were 36.06 ± 4.31 mm, 3.91 ± 0.66 mm, and 9.16 ± 1.52 mm, respectively. Meanwhile, the convex side is 37.52 ± 1.84 mm, 5.20 ± 0.55 mm, and 11.05 ± 0.70 mm, respectively. We found a significant difference between the concave and convex sides for the pedicle width and height. The concave and convex sides were mainly classified as type C (38%) and type A (50%) Watanabe pedicle.ConclusionPedicle width and pedicle height are significantly different between the concave and the convex side with convex side has better Watanabe pedicle classification. Pre-operative CT evaluation is essential for planning proper pedicle screw placement in AIS patients.

Mechanical properties of mortise-tenon joints reinforced by self-tapping screws with different insertion methods

The mortise-tenon (MT) joints are kind of traditional connection for structural components in China, which can get better connection performance by reinforcement. In this paper, different self-tapping screw (STS) insertion methods were applied to reinforce the MT joints, and cyclic loading were carried out for one group of unreinforced joint and three groups of reinforced joints. The load-carrying capacity, strength, stiffness, ductility, and energy dissipation capacity of each group were evaluated. The results showed that STS inserted horizontally could significantly reduce the pull-out of the tenon and improve the load-carrying capacity of the joints. The joints reinforced by two horizontally inserted STS had a higher load-carrying capacity than those reinforced by one STS with horizontal insertion, although the former might accelerate the damage to joints. Inclined insertion of STS for joints provided higher stiffness, ductility and energy dissipation capacity, while the load-carrying capacity was inferior to that of the reinforced joints with STS horizontally inserted. This paper provides data for reinforcing MT joints with STS, so as to select different reinforcement methods for different engineering requirements.

Biomechanical comparison of pedicle screw fixation strength among three different screw trajectories using single vertebrae and one-level functional spinal unit.

Three key factors are responsible for the biomechanical performance of pedicle screw fixation: screw mechanical characteristics, bone quality and insertion techniques. To the best of the authors' knowledge, no study has directly compared the biomechanical performance among three trajectories, i.e., the traditional trajectory (TT), modified trajectory (MT) and cortical bone trajectory (CBT), in a porcine model. This study compared the pullout strength and insertion torque of three trajectory methods in single vertebrae, the pullout strength and fixation stiffness including flexion, extension, and lateral bending in a one-level instrumented functional spinal unit (FSU) that mimics the in vivo configuration were clarified. A total of 18 single vertebrae and 18 FSUs were randomly assigned into three screw insertion methods (n = 6 in each trajectory group). In the TT group, the screw converged from its entry point, passed completely inside the pedicle, was parallel to the superior endplate, was located in the superior third of the vertebral body and reached to at least the anterior third of the vertebral body. In the MT group, the convergent angle was similar to that of the TT method but directed caudally to the anterior inferior margin of the vertebral body. The results of insertion torque and pullout strength in single vertebrae were analyzed; in addition, the stiffness and pullout strength in the one-level FSU were also investigated. This study demonstrated that, in single vertebrae, the insertion torque was significantly higher in CBT groups than in TT and MT groups (p < 0.05). The maximal pullout strength was significantly higher in MT groups than in TT and CBT groups (p < 0.05). There was no significant difference in stiffness in the three motions among all groups. The maximal pullout strength in FSUs of MT and CBT groups were significantly higher than the TT groups (p < 0.05). We concluded that either MT or CBT provides better biomechanical performance than TT in single vertebrae or FSUs. The lack of significance of stiffness in FSUs among three methods suggested that MT or CBT could be a reasonable alternative to TT if the traditional trajectory was not feasible.

Efficiency of Long Lateral Mass Screws.

Introduction: Lateral mass screws (LMS) have been widely used for the posterior fusion of the cervical spine. Even though LMS are safe, the screws are short and postoperative fixation is uncertain. Therefore, we measured and reported a technique using long lateral mass screws (LLMS), a new method of screw insertion, using a Zed spine from LEXI (Tokyo, Japan). Materials and Methods: In this study, we evaluated the outcomes of 35 patients who underwent surgery using LLMS at our hospital from 2019 to 2021. Operative time, blood loss, complications, inserted screw length, screw length based on gender differences, and screw deviation rate were evaluated. The Mann–Whitney U test was used to determine the gender differences in screw length. Screw deviation was evaluated by postoperative CT and a Zed spine to determine the screw insertion angle. Results: The mean operative time was 185 ± 51 min (120–327 min), and the mean blood loss was 236 ± 316 g (10–1720 g). The total number of screws was 183. The screw length was 22.2 (16–28) mm for males and 20.8 (16–28) mm for females, with an average length of 21 ± 2.7 mm. No gender differences were observed in terms of screw length (p > 0.01 NS). The number of deviated screws above G3 was one in the third cervical vertebra, three in the fourth cervical vertebra, one in the fifth cervical vertebra, and one in the sixth cervical vertebra. The number of deviated screws was 6 out of 183, and the deviation rate was 3.2%. Conclusions: In this study, the LLMS deviation rate was 3.2%, and strong fixation was possible without any complications. We measured the screw length and screw deviation rate in cases in which LLMS were actually inserted.

Biomechanical Evaluation of the Transcortical and Transpedicular Trajectories for Pedicle Screw Insertion in Thoracolumbar Fracture Fixation for Ankylosing Spondylitis.

Background: Ankylosing spondylitis (AS) is a chronic disorder characterized by an imbalance between bone formation and resorption. Spinal fractures often occur after minor trauma in patients with AS. For thoracolumbar fractures, transpedicular screw (TPS) fixation through the posterior approach has been suggested. The cortical bone trajectory (CBT) technique has also been used to prevent screw pull-out in patients with poor bone quality. The aim of current study was to assess the biomechanical characteristics of the TPS and CBT technique in thoracolumbar AS fracture fixation by finite element analysis.Methods: The three-dimensional finite element models of the AS spine were created. The CBT and TPS methods of screw insertion were used in AS spinal fracture models. An intact AS spine model was considered the control. An axial force and torsion in rotation, flexion/extension and lateral flexion were applied in all models in CBT, TPS, and control groups.Results: The AS spine showed similar construct stiffness after posterior fixation by CBT and TPS techniques under axial, rotational, and flexion/extension loading conditions. The TPS technique showed better intact stability under all loading conditions. Similarly, the TPS technique provided superior fracture regional stability against axial and rotational loads than did the CBT technique. The maximum von Mises stresses were 1714.4 ± 129.8 MPa and 1208.7 ± 107.3 MPa (p < 0.001), which occurred in the CBT and TPS groups under compressive loading.Conclusions: The TPS technique provides better biomechanical strength under axial, rotational, flexion/extension, and lateral flexion loading than does the CBT technique. Compared with CBT, TPS is more effective in maintaining the stability of AS thoracolumbar fractures from a finite element analysis perspective.

Assessment of pedicle size in patients with scoliosis using EOS 2D imaging: a validity and reliability study

PurposeFree-hand pedicle screw insertion methods are widely used for screw insertion during scoliosis surgery. Preoperative knowledge about the pedicle size helps to maximize screw containment and minimize the risk of pedicle breach. Radiographs taken by a biplanar low-dose X-ray device (EOS) have no divergence in the vertical plane. The criterion validity and reliability of preoperative EOS images for pedicle size measurements in patients with idiopathic scoliosis (IS) was investigated in this study.MethodsSixteen patients who underwent surgical treatment for IS were prospectively included. Intra- and extracortical pedicle height and width measurements on EOS images were compared with reconstructed intra-operative 3D images of the isthmus of included pedicles. Secondly, intra- and interobserver reliability of pedicle size measurements on EOS images was determined.ResultsThe total number of analyzed pedicles was 203. The correlation between the EOS and 3D scan measurements was very strong for the intra- and extracortical pedicle height and strong for the intra- and extracortical pedicle width. There are, however, significant, but likely clinically irrelevant differences (mean absolute differences < 0.43 mm) between the two measure methods for all four measurements except for extracortical pedicle height. For pedicles classified as Nash–Moe 0, no significant differences in intra- and extracortical pedicle width were observed. Both intra- and interobserver reliability was excellent for all pedicle size measurements on EOS images.ConclusionThe results of this study indicate a good validity and reliability for pedicle size measurements on EOS radiographs. Therefore, EOS radiographs may be used for a preoperative estimation of pedicle size and subsequent screw diameter in patients with IS.

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

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

Comparison of the Accuracy of C1 Pedicle Screw Fixation Using Fluoroscopy and Free-Hand Techniques in Patients With Posterior Arch Thickness of Less Than 4 mm.

C1 pedicle screw insertion is not easy, and more fluoroscopy can be required for safe insertion. Fluoroscopy is time consuming and increases patient radiation exposure. There have been no studies comparing the accuracy of C1 pedicle screw insertion using the fluoroscopy and free-hand techniques. To describe a free-hand C1 pedicle screw insertion method in patients with the posterior arch thickness of less than 4 mm in the thinnest part of the groove, and to compare the clinical and radiological outcomes of C1 pedicle screw insertion using fluoroscopy vs using the free-hand technique. A total of 25 patients who had atlantoaxial instability with a C1 posterior arch<4 mm and were treated with C1 pedicle screw insertion were included. In 10 patients, fluoroscopy was used for C1 pedicle screw insertion, and 15 patients underwent the free-hand technique. We compared the radiologic and clinical outcomes between the 2 groups. In patients who underwent the free-hand technique, 96.5% of screws were rated as safe (grade A or B), and 80.0% of screws in the fluoroscopy group were rated as safe. Postoperative occipital neuralgia occurred in one patient in the fluoroscopy group and did not occur in the free-hand technique group. There was no significant difference in the improvement of Nurick grade between the 2 groups. C1 pedicle screw insertion using the free-hand technique is feasible and safe in patients with a C1 posterior arch<4 mm.

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

BACKGROUND CONTEXT 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 3-dimensional (3D) spinal anatomic and 2-dimensional (2D) navigation images are directly projected onto the operators’ retina and superimposed over the surgical field eliminating field of vision and attention shift to a remote display. The objective of this study was to assess the accuracy and precision of percutaneous ARMSS pedicle implant insertion. PURPOSE To assess the clinical accuracy and technical precision of head-mounted display (HMD) augmented reality (AR) assisted percutaneous pedicle screw insertion. STUDY DESIGN/SETTING Cadaveric accuracy and precision study. PATIENT SAMPLE Not applicable. OUTCOME MEASURES Not applicable. METHODS Five cadaveric torsos were ARMSS instrumented with the xvision AR-HMD platform (Augmedics; Chicago, IL) at levels ranging from T5 to S1 for a total of 113 total implants comprised of 93 pedicle screws and 20 jamshidi needles. Postprocedural computed tomography (CT) scans were graded by two independent neuroradiologists using the Gertzbein scale (GS A-E) for clinical accuracy. Technical precision was calculated via superimposition analysis employing the Medical Image Interaction Toolkit (MITK; Heidelberg, Germany) to yield angular trajectory (°) and screw tip (mm) linear deviation from the virtual pedicle screw position vs the actual pedicle screw position on post-procedural CT imaging. RESULTS The overall implant insertion clinical accuracy achieved was 99.1%. Sacro-lumbar and thoracic clinical accuracy was 100% and 98.3%, respectively. Specifically, among all implants inserted, 112 were noted to be GS A or B (99.12%) with only 1 medial GS C breach (>2 mm pedicle breach) in a thoracic pedicle at T9. Precision analysis of inserted pedicle screws yielded a mean screw tip linear deviation of 1.98 mm [99% CI:1.74 – 2.21 mm] and a mean angular error of 1.29° [99% CI:1.11° – 1.46°] from the projected trajectory. The latter data compare favorably to existing navigation platforms and regulatory precision requirements mandating that linear and angular deviation be below 3 mm (p CONCLUSIONS Percutaneous ARMSS pedicle implant insertion is a technically feasible, accurate, and highly precise method. FDA DEVICE/DRUG STATUS This abstract does not discuss or include any applicable devices or drugs.

Accuracy and safety of cortical bone trajectory screw placement by an inexperienced surgeon using 3D patient-specific guides for transforaminal lumbar interbody fusion

Cortical bone trajectory (CBT) is an alternative method for pedicle screw insertion. However, identification of the optimal entry point and the direction of the CBT can be challenging for less-experienced surgeons. The purpose of this study was to evaluate the accuracy of the CBT screw placement by an inexperienced surgeon using a three-dimensional (3D) patient-specific guide for transforaminal lumbar interbody fusion (TLIF). Retrospective analysis of the data pertaining to 30 patients (128 screws) who underwent TLIF with CBT by an inexperienced surgeon using a 3D patient-specific guide (MySpine MC, Medacta) at a single center was performed. The accuracy of the CBT screw was graded into four groups (no perforation; Grade A, 0–2 mm; Grade B, 2–4 mm; and Grade C, > 4 mm). The accuracy of the CBT screw placement was 91% (116/128). Out of the 12 misplaced screws, Grade A was observed in 7 screws (5%), Grade B was observed in 3 screws (2%), and Grade C was observed in 2 screws (2%). There were no cases of medial pedicle wall perforation. The mean screw size was 5.95 ± 0.34 mm in diameter and 40.15 ± 2.83 mm in length. Note that, the accuracy of the CBT screws increased to 97% (83/86) over the first10 cases. Preoperative planning and 3D patient-specific guide enabled the use of longer and thicker screws and an optimal entry point. These results suggest the possibility of efficacy and safety in using 3D patient-specific guides for CBT screw placement by an inexperienced surgeon.

Does image guidance decrease pedicle screw-related complications in surgical treatment of adolescent idiopathic scoliosis: a systematic review update and meta-analysis.

Surgical treatment of severe adolescent idiopathic scoliosis (AIS) with posterior spinal instrumentation and fusion with pedicle screws is common, requiring careful screw insertion to prevent pedicle breaches and neurologic complications. Image guidance has been suggested to improve breach rates, though the radiation risk for AIS precludes its common usage. The purpose of this systematic review and meta-analysis was to compare the breach rates and screw-related complications for AIS patients undergoing spine surgery with pedicle screws between freehand screw insertion and image guidance methods. A comprehensive search of MEDLINE, EMBASE, CINAHL, CENTRAL and Web of Science databases was conducted. Two reviewers independently screened abstracts, full-texts, extracted data and performed risk of bias assessment using the QUIPS quality appraisal tool. Level of evidence summary statements were formulated based on consistency and quality of reporting. Ninety-four studies were found, with 18 studies of moderate risk of bias or better. Moderate evidence from two head-to-head studies shows CT guidance has lower breach rates than freehand methods (OR 0.28 [0.20-0.40, I2 = 1%]), with no complications in either study. From individual studies, moderate evidence showed lower breach rates for image guidance versus freehand methods (13%, I2 = 98% vs. 20%, I2 = 95%). Complication rates were conflicting (0-1.6% for image guidance, 0-1.7% for freehand). Moderate evidence showed increased surgical time for image guidance versus freehand (257.7min vs. 226.8min). Meta-analyzed breach rates show moderate evidence of decreased breaches with CT navigation compared with freehand methods. Complication rates remain unknown due to the low complication rates from small sample sizes. These slides can be retrieved under Electronic Supplementary Material.

Transcranial Insertion of Atlas Facetal Screw for Atlantoaxial Fixation

We evaluated the technical feasibility and potential advantages of transcranial insertion of an atlas screw for atlantoaxial fixation. From January 2016 to August 2018, the transcranial technique for atlas screw insertion was used in 6 patients. Conventional lateral mass atlantoaxial fixation was not possible because of the presence of a complex craniovertebral junctional abnormality and difficulty in direct exposure of the facet of the atlas. In all cases, severe basilar invagination and assimilation of the atlas was present. Of the 6 patients, 3 were male and 3 were female. The age range was 12-41 years (average, 23 years). The surgical technique involved a small suboccipital craniotomy in line with the facet of the axis. Extradural elevation of the cerebellum exposed the region of the occipital condyle and fused atlas. The screw was directed medially and inferiorly into the facet of the atlas. In all 6 patients, strong and successful atlantoaxial fixation was achieved. All patients showed clinical improvement after surgery. At an average follow-up period of 21 months, successful arthrodesis of atlantoaxial joint had been achieved in all 6 patients, with no complications. Transcranial insertion of atlas screw can be used as a salvage procedure when the conventional method of screw insertion is not possible because of technical difficulties.

Novel Screw Insertion Method for Anterior Surgical Treatment of Unstable Thoracolumbar Fracture: Quadrant Positioning Method.

ObjectiveTo develop a novel screw positioning method to improve the treatment of unstable thoracolumbar fractures.MethodsA total of 72 patients with unstable thoracolumbar fractures who were treated with anterior screw–rod interfixation from January 2011 to October 2015 were included in this clinical study. Those patients included 48 male and 24 female patients with an average age of 45.10 years (range, 26–63 years). Patients were randomly divided into two groups: an observation group (n = 36) and a control group (n = 36). The quadrant positioning method was used for screw insertion in the observation group during the operation, while the traditional screw positioning method was used in the control group. The quadrant positioning method targeted four quadrants, including the superior anterior (SA), superior posterior (SP), inferior anterior (IA) and inferior posterior (IP) quadrants, while for the traditional screw positioning, four screws were inserted into the vertebral bodies above and below the excision. Patients were followed up for approximately 40 months to record recovery. Clinical and radiological records, local angle and fractured vertebra body height, clinical outcomes, complications, neurological improvement, and fusion rate were recorded and compared between the two groups.ResultsThe quadrant positioning method was successfully used for anterior screw insertion. The quadrant center in the lateral view of the vertebral body was well marked, and screws were easily located on the scheduled quadrant. Blood loss (BL), hospital stay (HS), and operation time (OP) in the observation group were 749.40 ± 379.90 mL, 17.10 ± 4.10 days, and 167.40 ± 44.70 min, respectively. While those parameters in the control group were 1198.40 ± 339.27 mL, 23.22 ± 3.77 days, and 221.47 ± 32.15 min, respectively. The average operation time and hospital stay time were significantly shorter, and blood loss was significantly less in the observation group than in the control group (P < 0.05). Local angle and vertebral body height were markedly improved and 1–2 grade improvement was achieved in patients with neurological deficits in both groups. Both groups of patients achieved bony fusion during follow‐up. No incision infection or internal fixation failure was observed in the two groups, and complications including cerebrospinal fluid and chylous leakage and hemothorax were resolved.ConclusionsThe quadrant positioning method can shorten operation time, reduce blood loss, and accelerate postoperative recovery. The technique provides an effective method for screw insertion for double screw–rod instrumentation fixation in the treatment of thoracolumbar fracture via the anterior approach.

Augmented reality-assisted pedicle screw insertion: a cadaveric proof-of-concept study.

Augmented reality (AR) is a novel technology that has the potential to increase the technical feasibility, accuracy, and safety of conventional manual and robotic computer-navigated pedicle insertion methods. Visual data are directly projected to the operator's retina and overlaid onto the surgical field, thereby removing the requirement to shift attention to a remote display. The objective of this study was to assess the comparative accuracy of AR-assisted pedicle screw insertion in comparison to conventional pedicle screw insertion methods. Five cadaveric male torsos were instrumented bilaterally from T6 to L5 for a total of 120 inserted pedicle screws. Postprocedural CT scans were obtained, and screw insertion accuracy was graded by 2 independent neuroradiologists using both the Gertzbein scale (GS) and a combination of that scale and the Heary classification, referred to in this paper as the Heary-Gertzbein scale (HGS). Non-inferiority analysis was performed, comparing the accuracy to freehand, manual computer-navigated, and robotics-assisted computer-navigated insertion accuracy rates reported in the literature. User experience analysis was conducted via a user experience questionnaire filled out by operators after the procedures. The overall screw placement accuracy achieved with the AR system was 96.7% based on the HGS and 94.6% based on the GS. Insertion accuracy was non-inferior to accuracy reported for manual computer-navigated pedicle insertion based on both the GS and the HGS scores. When compared to accuracy reported for robotics-assisted computer-navigated insertion, accuracy achieved with the AR system was found to be non-inferior when assessed with the GS, but superior when assessed with the HGS. Last, accuracy results achieved with the AR system were found to be superior to results obtained with freehand insertion based on both the HGS and the GS scores. Accuracy results were not found to be inferior in any comparison. User experience analysis yielded "excellent" usability classification. AR-assisted pedicle screw insertion is a technically feasible and accurate insertion method.

Preliminary application of 3D printing navigation template in the screw insertion of the suprapubic fracture

Objective To introduce the method of using hollow pull screw insertion for the suprapubic fracture with 3D printing navigation template and to evaluate its clinical effect. Methods From March 2016 to August 2017, eighteen cases of suprapubic ramus fractures treated with hollow lag screw fixation in the Department of Orthopedics of Yanan University Affiliated Hospital were retrospectively collected was collected.Before operation, the thin slice CT scan of pelvis was used to get raw data, and the mimics17.0 software was used to reconstruction the model, to design and make the personalized navigation template assisting the suprapubic fractures surgery.The navigation template was printed out pre-operatively, and the nail was inserted via the assisted by the template intra-operatively.After the operation, the fracture reduction was evaluated by Matta imaging scores and the pelvis function was evaluated by Majeed scores. Results All the operations were successfully completed.The Matta scores were excellent in 11 cases, good in 6 cases, and fair in 1 case.The Majeed scores were excellent in 13 cases, good in 3 cases, and fair in 2 cases. Conclusion 3D Printing navigation template assisted the placement of the hollow screw on the suprapubic fracture could provide personalized treatment, reduce the difficulty of operation and satisfy the clinical effect. Key words: 3D printing navigation template; suprapubic fracture; Retrospectively study