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Purpose: To investigate the resistance of an implant crown telescopically engaged to a geometrically defined hexagonal abutment with and without cement under compressive dynamic cyclic fatigue loading. Materials and Methods: 40 crowns, 9 mm in height, were cast from prefabricated plastic copings, each telescopically engaged to a 3-mm-high machined hexagonal abutment. 20 crowns were retained with zinc phosphate cement, and 20 crowns were retained with a screw. A vertical load of 15 kg was applied to all samples under oscilla)on. A Periotest was used to measure the mobility of the implant crown in Periotest values (PTV). Test endpoints were defined by the following: fa)gue cycles ≥ 20 million; crown PTV > 10; or if samples became visibly loose or component fracture. Results: Cement-retained crowns failed on average at 2.60 x 106 cycles ± 2.27, while screw-retained crown samples failed at 2.17 x 106 cycles ± 1.27 with no significant difference (P > .05). Implant and abutment screw fractures were the most prevalent mode of failure in the cement-retained group, while in the screw-retained group, failures were caused by the loosening of one or both screw joints. The rate of increase in PTV was higher in the screw-retained group than in the cement-retained group. Conclusions: Under the experimental condi)ons, an implant crown telescopically engaged ver)cally to a 3-mm-tall hexagonal abutment, under compressive dynamic cyclic fa)gue loading with or without cement, demonstrated no differences in resistance or failure outcomes. A cement-retained implant crown with telescopic engagement to the abutment is more rigid, resul)ng in more implant and abutment screw fractures than loosening. [ABSTRACT FROM AUTHOR]

Purpose: To assess if the implant-retained prostheses produced with laser-sintering technique present an accuracy and passive fit comparable to their milled counterpart. Materials and Methods: Two regular neck Straumann analogs were placed in a block of PMMA 15 mm apart and parallel to each other. The PMMA block was then scanned and two groups of cobalt-chromium, screw-retained, three-unit implant prostheses were fabricated using milling (control) and laser-sintering (test) techniques. The prostheses were then screwed on the PMMA block and the verFcal marginal gap between the prostheses and the analogs at the implant-abutment juncFon was measured twice, (1) when only one screw was Fghtened, and (2) when both screws were fully Fghtened. The average of each marginal gap measurement was compared to assess the difference in term of passive fit between the laser-sintered and the milled prostheses. Results: The mean marginal gap of the milled and the laser-sintered groups were 23.18 µm (SD = 6.2) and 23.71 µm (SD = 19.5) respecFvely. Conclusions: Laser-sintered prostheses presented a marginal fit comparable to their milled counterpart and represent a clinically valid alternaFve to their milled counterpart. [ABSTRACT FROM AUTHOR]

Facet joint violation by pedicle screws may lead to adjacent-segment disease and postoperative pain. Previous studies have reported the incidence of rostral facet joint violation using various pedicle screw insertion techniques. However, the incidence of facet joint violations with robotic guidance has not been determined. To investigate and compare the incidence of rostral facet joint violation by pedicle screws under robotic guidance and computerized tomography (CT) navigation guidance. Retrospective matched cohort. All patients who underwent robotic-assisted lumbar fusion at a major spine center up until 2023 were retrospectively identified and matched 1:3 to patients undergoing CT navigation guidance based by on age, sex, rostral vertebral level, and length of construct. Inclusion criteria consisted of age greater than 18 years, bilateral pedicle screw fixation, and presence of a postoperative CT scan of the lumbar spine or abdomen/pelvis at any point in the postoperative period. Rostral facet joint violations. Descriptive statistics were used to compare cohorts: frequencies, chi-squared analysis for categorical variables, and t-test for continuous variables. A total of 408 rostral pedicle screws were implanted in 204 patients (Robot: 102; Navigation: 306). Overall, 13 (12.3%) rostral facet joint violations were observed in the robot cohort and 75 (24.5%) in the navigation cohort (p=.01). Specifically, fewer robotic violations were observed at the L2 (3.5% vs 32.1%, p=.003) and L3 levels (3.9% vs 18.1%, p=.08) compared to navigation. No difference was observed at L4 and L5. Bilateral violations are significantly reduced with robotic approaches (5.3% vs 14.4%, p=.03). Lastly, more facet joint violations were observed during open approaches (robot: 18.8%, navigation: 27.3%) than percutaneous approaches (robot: 11.6%, navigation: 7.1%) in both groups (p<.001). The rate of L4 facet violations was 18.8% in the robotic cohort and 27.3% in the navigation cohort. The rate of L5 facet violations was 31.3% in the robotic cohort and 29.2% in the navigation cohort. Use of robotic assistance in lumbar pedicle screws significantly reduced the rate of rostral facet joint violations compared to navigation guidance at L2 and L3 levels, but not at L4 and L5, with facet violations approaching nearly one-third of the patients at L5 screws. Rostral facet violations can play a significant role in adjacent segment degeneration and disease. Technical factors and trajectory issues likely play a role and addressing these components should minimize unintended facet violation and proximal adding on. [ABSTRACT FROM AUTHOR]

Objective. To examine the shape change of screw-rod constructs over time after short-segment lumbar interbody fusion and to clarify its relationship to clinical characteristics. Summary of Background Data. No study has focused on the shape change of screw-rod constructs after short-segment fusion and its clinical implications. Methods. One hundred eight patients who had single-level lumbar interbody fusion with pedicle screws and cages were enrolled. Three-dimensional (3D) images of screw-rod constructs were generated from baseline CT on the day after surgery and followup CT and were superposed on the right and left side, respectively, using the iterative closest point algorithm. The shape change was quantitatively assessed by computing the median distance between the 3D images, which was defined as the shape change value. Among the 5 time-course categories of follow-up CT (=1, 2-3, 4-6, 7-12, and =13 months), the shape change values were compared. The relationships between the shape change values and clinical characteristics, such as age, CT-derived vertebral bone mineral density, screw and rod materials, and postoperative interbody fusion status, cage subsidence, and screw loosening, were evaluated. Results. A total of 237 follow-up CTs were included (=1 [34 scans], 2-3 [33 scans], 4-6 [80 scans], 7-12 [48 scans], and = 13 months [42 scans]) because many patients underwent multiple follow-up CTs. There were significant differences in shape change values among the time-course categories (P<0.001 in Kruskal-Wallis test). Most shape changes occurred within 6 months postoperatively, with no significant changes observed at 7 months or more. There were no significant relationships between the shape change values and each clinical characteristic. Conclusions. The temporal shape changes of screw-rod constructs following short-segment lumbar interbody fusion progressed up to 6 months after surgery but not significantly thereafter. [ABSTRACT FROM AUTHOR]

Introduction: Either in conservative or in surgical management of maxillo‐mandibular fractures, intermaxillary fixation (IMF) provides stable occlusion, while offering reduction in the fractured segments. Various techniques have been used for achieving IMF, among which Erich arch bar is the most conventional and routinely used technique. However, it poses a risk of percutaneous injury to the surgical team with every wire used in the technique, causes trauma to the periodontium of the teeth secured by wires and it is not very comfortable for the patient. The few IMF techniques that are recommended without wire require special armamentarium that are not universally available. Materials and Methods: Our novel IMF technique employing multiple looping of orthodontic E chains around IMF screws can provide adequate reduction and stabilization of the fractured segments with good occlusion before plating of the maxillo‐mandibular fractures. It can also be utilized for extended periods for closed reduction or postoperatively for guiding the occlusion. Results: As seen in our clinical experience using this novel technique, there is no risk of percutaneous injury to the surgical team. It provides stable occlusion, optimal reduction in the fractured segments and is accepted well by patients as no wires are used. Conclusion: This novel technique can be used in all patients who require IMF and is particularly useful in patients with periodontally compromised teeth or in those who are partially edentulous where conventional arch bar fixation cannot be performed. This technique will considerably reduce the operative time and aid in better patient compliance. [ABSTRACT FROM AUTHOR]

In this research, experimental studies and numerical analyses were carried out to investigate how the usage of geotextile and geopolymer coated geotextile as a hybrid method changes the uplift behavior of the screw piles in cohesionless soil. In this context, traditional pile behavior, the effect of different number of helixes and embedment depths on screw piles, the mechanism of geotextile and the effects of geopolymer coating process were investigated. In addition, experimental studies were modeled by using Plaxis 3D and parametric studies were carried out after verification between the results of experimental study and numerical analysis. In the numerical analysis, a segmented helix model consisting of four 90-degree slices was developed instead of the planar helixes commonly used in the literature. For further investigation of the effectiveness of hybrid method, parameters such as improvement ratios and breakout factors were calculated. When the results obtained within the scope of the study were evaluated, the geopolymer coating process increased the bearing capacity of the geotextile by 24 % at 27 % less elongation. It was also seen that uncoated and geopolymer coated geotextile increased the screw pile performance in terms of improvement ratios by 294 % and 364 %, respectively. [Display omitted] [ABSTRACT FROM AUTHOR]

Calcaneal body fractures are often associated with varying degrees of shortening deformities. Restoring calcaneal length is crucial for the functional prognosis of the foot. Through finite element analysis, this study compared the biomechanical effects of multiple fixation schemes for calcaneal fractures. We delineated and assembled the finite element model of the Sanders type II calcaneal fracture and four internal fixation simulations (namely distraction screw, lag screw, frame locking plate, and T-shaped locking plate). Different axial forces (350, 700, and 1400 N) were then applied to simulate various postures. We then compared the inner and outer shortening distances (D1 and D2, respectively), equivalent von Mises stress, and maximum von Mises stress of the calcaneus. In the individual model, with an increase in the pressure, D1, D2, and the maximum von Mises stress gradually increased. At 1400 N, D1 and D2 for the internal fixation schemes were as follows: distraction screw (0.03 mm, 0.1 mm) < T-shaped locking plate (0.45 mm, 0.26 mm) < frame locking plate (0.50 mm, 0.26 mm) < lag screw (0.66 mm, 0.64 mm). The maximum von Mises stress values for the internal fixation methods were as follows: lag screw (491.0 MPa) < distraction screw (663.1 MPa) < frame locking plate (772.7 MPa) < T-shaped locking plate (931.8 MPa). In patients with calcaneal body fractures, the distraction screw is a potential therapeutic option for resisting calcaneal shortening. [ABSTRACT FROM AUTHOR]

Screws are extensively utilised across various domains. However, the problem of screw loosening not only impacts the stability and safety of engineering structures but also poses the risk of severe accidents and losses. The hollow design of hexagonal screw heads limits the effectiveness of conventional methods for detecting screw loosening. Additionally, traditional visual detection methods are influenced by the surrounding environment, affecting detection accuracy. To tackle these challenges, this study introduces a novel approach based on deep learning for detecting loosened hexagonal screws. This method primarily relies on the you only look once version 8 (Y0L0v8) algorithm to accurately detect the coordinates of the four key points of the hexagonal screw. By applying geometric imaging theory, equations are derived for calculating the loosening angle and length of hexagonal screws. By utilising these equations along with bolt parameters, the degree of loosening is determined. Furthermore, photos captured in low-light environments are enhanced using an improved automatic colour enhancement (ACE) algorithm, which saturates image colours to improve environmental adaptability. This enhancement facilitates better recognition of hexagonal screws even in dark environments. Four colour enhancement methods are also evaluated based on four criteria. Moreover, by employing a back-propagation (BP) neural network for error compensation, the proposed method brings predicted values closer to actual values. The experimental results demonstrate an angular identification error of less than l°and a length identification error of less than 1 mm for loose hexagonal screws. [ABSTRACT FROM AUTHOR]

To investigate the biomechanical properties of pedicle screw reinsertion along the same trajectory in a previously validated synthetic bone model. Twenty identical acrylonitrile butadiene styrene models of lumbar vertebrae were three-dimensional-printed. Screws were placed in the standard fashion into each pedicle. Models were separated into 2 equal groups, control and experimental. Experimental group screws were completely removed from their testing block and reinserted once. All screws in both groups were then forcibly removed. Continuous torque monitoring was collected on screw insertion torque (IT), removal torque, and reinsertion torque. Pullout strength (PO), screw stiffness (STI), and strain energy (STR) were calculated. There was no significant difference between control and experimental groups for PO (P = 0.26), STI (P = 0.55), STR (P = 0.50), or IT (P = 0.24). There was a significant decrease in reinsertion torque (54.5 N-cm ± 8.2 N-cm) from control IT (62.9 N-cm ± 8.4 N-cm, P = 0.045) and experimental IT (67.5 N-cm ± 7.6 N-cm, P = 0.0026). Strong correlations (Pearson's r > 0.80) were seen between control IT against STR and PO, between each of the experimental torque measurements, and between experimental PO and STI. Despite a significant decrease in insertion torque, there is no significant loss of pedicle screw performance when a screw is removed and reinserted along the same trajectory. [ABSTRACT FROM AUTHOR]

To compare the stability of a corticopedicular posterior fixation (CPPF) device with traditional pedicle screws for decompression and fusion in adult degenerative lumbar spondylolisthesis. Finite element analysis (FEA) was used in a validated model of grade 1 L4–L5 spondylolisthesis to compare segmental stability after laminectomy alone, laminectomy with pedicle screw fixation, or laminectomy with CPPF device fixation. A 500-N follower load was applied to the model and different functional movements were simulated by applying a 7.5-Nm force in different directions. Outcomes included degrees of motion, tensile forces experienced in the CPPF device, and stresses in surrounding cortical bone. At maximum loading, laminectomy alone demonstrated a 1° increase in flexion range of motion, from 6.35° to 7.39°. Laminectomy with pedicle screw fixation and CPPF device fixation both reduced spinal segmental motion to ≤1° at maximum loading in all ranges of motion, including flexion (0.94° and 1.09°), extension (–0.85° and –1.08°), lateral bending (–0.56° and –0.96°), and torsion (0.63° and 0.91°), respectively. There was no significant difference in segmental stability between pedicle screw fixation and CPPF device fixation during maximum loading, with a difference of ≤0.4° in any range of motion. Tensile forces in the CPPF device remained ≤51% the ultimate load to failure (487 N) and stress in surrounding cortical bone remained ≤84% the ultimate stress of cortical bone (125.4 MPa) during maximum loading. CPFF fixation demonstrated similar segmental stability to traditional pedicle screw fixation whereas tensile forces and stress in surrounding cortical bone remained below the load to failure. [ABSTRACT FROM AUTHOR]

The goal of this study was to analyze our initial experience using a novel porous fusion/fixation screw (PFFS) for pelvic fixation and determine our rate of screw malposition requiring intraoperative repositioning. We reviewed 83 consecutive patients who underwent sacropelvic fixation with PFFS at our institution from June 1, 2022 to June 30, 2023 using intraoperative computed tomography–based computer-assisted navigation via an open posterior approach. Following PFFS insertion, intraoperative computed tomography scans were obtained to assess screw positioning. Demographic data were collected, and operative reports and patient images were reviewed to determine what implants were used and if any PFFS required repositioning. Seventy-four patients (26M:48F) were included, and 57 (77.0%) had a prior sacroiliac joint or lumbar spine surgery. A stacked screw configuration was used in 62/74 cases (83.8%). A total of 235 PFFS were used and six (2.6%) were malpositioned. Of 88 cephalic screws placed in stacked configuration, 4 were malpositioned (4.5%) and 1/123 caudal screws were malpositioned (0.8%). One of 24 sacral-alar-iliac screws placed in a stand-alone configuration was malpositioned (4.2%). Malpositions included 4 medial, 1 lateral, and 1 inferior, and all were revised intraoperatively without major sequela. Although PFFSs are larger than traditional sacropelvic fixation screws, stacked sacral-alar-iliac instrumentation can be done safely with computer-assisted navigation. We found a low malposition rate in our initial series of patients, the majority being the cephalad screw in a stacked configuration. This isn't surprising, as these are placed after the caudal screws, which reduces the available corridor size and increases the placement difficulty. [ABSTRACT FROM AUTHOR]

In this paper, different hybrid propulsion screw structures are analysed based on EDEM-CFD. Firstly, three screw models with different perturbation directions are established to analyse the mixing effect of ordinary screw, axial-disturbed screw and radial-disturbed screw based on EDEM. Then the trends of anti-skid coating volume fraction changes within the three structures are simulated by CFD. Finally, the prototype was prepared and experimented. The results show that the volume fraction inside the radial-disturbed screw is 5 times that of the axial-disturbed screw and 6 times that of the common screw, indicating that the radial-disturbed is more favourable to the mixing of anti-slip coatings. The performance of radial-disturbed screw mixing was found to be higher than that of manual mixing by impact and compression experiments, which verified the correctness of the analysis. [ABSTRACT FROM AUTHOR]

Background: The most published surgical technique for fixating Type 4 (Salter–Harris II) tibial tubercle avulsion fractures is uni-cortical in nature, and stability is suboptimal. This study presents a technique modification that is consistent with AO principles, by which the screws are aimed distally to purchase the posterior cortex of the distal fragment. This technique is defined as a "Distal Cortical Fixation". This modification has not been studied to date and harbors potential advantages. We aimed to assess the safety and efficacy of surgical fixation techniques for the above-mentioned fractures and to describe the new modification. Methods: A retrospective review was conducted at a level 1 children's hospital for surgically treated Salter–Harris II tibial tubercle fractures. Inclusion criteria were patients who sustained Salter–Harris II tibial tubercle avulsion fractures and were documented to reach one of two radiographic endpoints: union (regardless of alignment) or non-union that necessitated additional interventions. Medical records and radiographic studies were analyzed for fracture union and alignment. A comparative analysis was conducted to evaluate outcomes based on different fixation techniques that included Distal Cortical Fixation, a Proximal Screw Technique, and a crossed or multiple screws/pins construct. Results: A total of 37 patients were included with a mean age of 14.8 ± 1.2 years, with 34/37 (91.9%) being male. The most common procedure was a 1 to 3 screw fixation with a Distal Cortical Fixation (n = 21 (56.75%)), followed by a Proximal Screw Technique (n = 8, 21.62%), and a crossed or multiple screws/pins construct (n = 8, 21.62%). There was no difference between the groups in medical history and demographic features. The mean follow-up duration was 35.17 ± 36.79 weeks. There were no non-unions, and only a minimal change in the sagittal and coronal alignment (0.4 ± 1.94 (p = 0.872) and 0.53 ± 3.51 (p = 0.296) degrees, respectively) was noted and was not associated with the surgical technique. Conclusions: The surgical treatment of Salter–Harris II tibial tubercle avulsion fractures, including Distal Cortical Fixation, was presented and was found to provide satisfactory union rates on a short term follow up. [ABSTRACT FROM AUTHOR]

A novel and original computer scaling-up system for the counter-rotating twin screw extrusion of polymers was developed. In the system, each scaling parameter (scaling criterion) may be considered as an objective function to be minimized for the single parameters or the functional relationships along the length of the screw. Scaling was based on the process simulation, which was performed using the comprehensive (or global) counter-rotating twin screw extrusion program called TSEM (Twin Screw Extrusion Model). The extrusion process was scaled by applying GASESTWIN (Genetic Algorithms Screw Extrusion Scaling) software developed for this purpose using genetic algorithms. Scaling up the extrusion process was carried out to enhance extrusion process throughput according to the scaling criteria specified by the single quantities of polymer melt temperature at the die exit and relative melting length, and by distributions along the screw length of the extrusion parameters of the polymer melt temperature and polymer plasticating. The global objective function had the lowest value for the selected extrusion parameters, which means the minimal differences between the values of the scaled-up processes and extrusion throughput was significantly increased. The solution to the problem of scaling the counter-rotating process presented in this paper complements the existing solutions for optimizing and scaling basic variants of the extrusion process, i.e., flood-fed and starve (metered)-fed single-screw extrusion, as well as co-rotating and counter-rotating twin-screw extrusion. [ABSTRACT FROM AUTHOR]

The processing conditions were varied during the production of polycarbonate-based composites with the multiwalled carbon nanotubes (MWCNTs) Baytubes® C150 P (Bayer MaterialScience AG, Leverkusen, Germany), by melt mixing with an extruder on a laboratory scale. These included the screw design, rotation speed, throughput, feeding position and MWCNT content. Particular attention was paid to the shortening of the MWCNT length as a function of the conditions mentioned. It was found that there is a correlation between the applied specific mechanical energy (SME) during the melt mixing process and MWCNT dispersion, which was quantified by the agglomerate area ratio of the non-dispersed nanotubes based on optical microscopic analysis. The higher the SME value, the lower this ratio, which indicates better dispersion. Above an SME value of about 0.4 kWh/kg, no further improvement in dispersion was achieved. The MWCNT length, as measured by the quantitative analysis of TEM images of the MWCNTs dissolved from the composites, decreased with the SME value down to values of 44% of the original MWCNT length. At a constant loading of 3 wt.%, the tensile strength and tensile modulus were almost independent of the SME, while the elongation at break and notched impact strength showed an increasing trend. The variation in the feeding position showed that feeding the MWCNTs into a side feeder led to slightly better electrical and mechanical properties for both types of MWCNTs studied (Baytubes® C150 P and Nanocyl™ NC7000 (Nanocyl S.A., Sambreville, Belgium)). However, feeding into the hopper led to better CNT dispersion with Baytubes® C150 P, while this was the case with Nanocyl™ NC7000 when feeding into the side feeder. The screw profile had an influence on the dispersion, the MWCNT length and the electrical resistance, but only to a small extent. Distributive screws led to a greater shortening of the MWCNT length than dispersive screws. By varying the MWCNT content, it was shown that a greater MWCNT shortening occurred at higher loadings. Two-stage masterbatch dilution leads to stronger shortening than composite production with direct MWCNT incorporation. [ABSTRACT FROM AUTHOR]

Purpose: Oblique lumbar interbody fusion (OLIF) has become a popular technique for treating adult degenerative scoliosis (ADS), but traditional OLIF technology often requires repositioning for one‐stage or staged posterior fixation. The objective of this pilot study was to describe the surgical technique of simultaneous single‐position OLIF and percutaneous pedicle screw fixation (OLIF 360) under O‐Arm navigation for modified MISDEF type II ADS. Methods: Between June 2022 and December 2023, six patients classified as having modified MISDEF type II ADS underwent OLIF 360 assisted by O‐Arm navigation at our institution. Intraoperative blood loss, duration of operation, and complications related to the OLIF 360 procedure were recorded. The preoperative and postoperative spinal pelvic parameters were measured using X‐rays. The accuracy of pedicel screws was recorded in accordance with the modified Gertzbein–Robbins classification on CT. Postoperative MRI was performed to evaluate the indirect decompressive effect. The Japanese Orthopedic Association score for low back pain was used to evaluate surgical outcomes. Results: Navigated OLIF 360 were performed in six ADS patients with 44 percutaneous pedicel screws and 16 cages placement, including four women and two men. The mean operation time was 160.83 ± 33.23 min, and the mean blood loss was 111.67 ± 39.71 mL. Postoperative spinal pelvic parameters and spinal stenosis degree improved significantly on X‐ray and MRI. All screws were clinically acceptable according to the Gertzbein–Robbins classification, with 92.7% grade A and 7.3% grade B. No serious intraoperative and postoperative adverse events were recorded in all patients. The JOA scores for low back pain of all patients were significantly improved at postoperative 1 month and the final follow‐up. Conclusion: We report on a case series and describe navigated OLIF 360 in treating modified MISDEF type II ADS patients. Navigation‐assisted OLIF 360 has shown encouraging surgical outcomes with good spinal imbalance correction and indirect decompression. [ABSTRACT FROM AUTHOR]

Objective: For degenerative diseases accompanied by cervical malalignment, the starting and ending points of fixation for better cervical sagittal alignment and clinical results are not as clear as the thoracolumbar region. In this study we aimed to compare the effects of posterior subaxial cervical fixation (PSCF), posterior cervical fixation extending to the upper thoracic region and posterior upper cervical fixation extending to the upper thoracic region on cervical sagittal alignment. Methods: Sixty‐three patients who underwent posterior cervical and cervical‐up thoracic fixation were retrospectively analyzed in a comparative study. The procedures that we performed from May 2019 to March 2022 on these 63 patients were: (1) C3‐C6 group—posterior subaxial cervical fixation; (2) Subaxial‐T2 group—posterior subaxial cervicothoracic fixation (PSCTF); (3) C2‐T2 upper thoracic posterior fixation group. The C3‐C6 group had 27 patients, Subaxial‐T2 group had 24, and C2‐T2 group had 12. We determined the minimum follow‐up period as 12 months. C0‐2, C2‐7 lordosis angle, sagittal vertical axis (SVA), C2 slope, C7 slope, T1 slope, cervical slope, neck slope, and thoracic inlet angle (TIA) measurements were made in three patient groups. Comparatively, cervical sagittal alignment was evaluated. Result: In the C2‐T2 group, a significant increase in C2‐C7 lordosis, decrease in C2 slope, and increase in TS‐CL were observed. Significant C2‐C7 lordosis decrease, C2 slope increase, and TS‐CL decrease were observed in the C3‐C6 group. A significant increase in C2‐C7 lordosis and a decrease in C2 slope were observed in the subaxial‐T2 group. No significant change was observed in the TS‐CL angle. Conclusion: In cervical degenerative disorders accompanied by cervical malalignment, we recommend the C2‐T2 fixation method, which provides the desired C2‐C7 lordosis, SVA within the normal range, and the best Neck Disability Index results. [ABSTRACT FROM AUTHOR]

Objective: The unclear clinical outcomes of two different zero‐profile implants with different number of screws in hybrid surgery restricts the choice of patient‐specific implants. This study aims to compare two different implants on its postoperative subsidence, motion stabilization and clinical outcomes. It also provides references to the most reasonable implant choice in fusion surgery. Methods: This was a retrospective study. From February 2014 to March 2022, 173 patients who underwent hybrid surgery were included. Among them, 122 received surgery with a four screw implant, while 51 received a two screw implant. We analyzed the significance of patient‐specific factors, radiographic factors and clinical outcomes. The Wilcoxon rank sum test, t tests/analysis of variance (ANOVA) test and stepwise multivariate logistic regression were adopted for statistical analysis. Results: No statistically significant difference was observed between the two screw and four screw groups in terms of immediate, middle, and long‐term stability and fusion rate (p > 0.05). However, the two screws group had higher FSU height subsidence at 3, 6, and 12 months postoperatively and higher rates of significant subsidence at three and 6 months postoperatively (p < 0.05). Both groups showed significant clinical improvements at the final follow‐up. Conclusion: Two screw and four screw implants provide comparable stability, fusion rates and clinical outcomes. However, the two screw implant was inferior to the four screw implant in subsidence prevention. Therefore, the two‐screw implant is non‐inferior to the four‐screw implant in most patients. It can be used as the priority choice in the fusion segment by its easy manageability. However, the patients with a high risk of subsidence such as multilevel surgery, the elderly, lower BMD, bad cervical alignment should receive a four screw implant rather than a two screw implant. [ABSTRACT FROM AUTHOR]

OBJECTIVE The objective of this study was to determine the effects of repeated steam sterilization cycles on the biomechanical properties of surgical screws. METHODS 42 3.5-mm and 42 2.0-mm self-tapping, cortical screws were divided into 3 groups per size and underwent autoclave sterilization for 1 (G1), 50 (G50), or 100 (G100) cycles and testing from August 2018 through June 2021. Sixty screws were then inserted into canine cadaver femurs, and biomechanical properties were measured, including peak insertional torque, torque to failure, and pullout strength, each normalized to cortical thickness. Scanning electron micrographs were taken from 24 screws, and images were blindly analyzed by 5 trained examiners. RESULTS The mean normalized insertion torque for 3.5-mm screws was significantly different between G1 and both G50 and G100. The mean normalized torque to failure for 3.5-mm screws was significantly different between G1 and both G50 and G100. Axial pullout testing was found to be significantly different for 2.0-mm screws between G1 and G100. Scanning electron micrographs surface scoring identified a significant difference in 3.5-mm screws at the screw tip. CONCLUSIONS The results indicate that biomechanical changes occur with repeated steam sterilizations. Specifically, peak insertional torque and torque to failure are decreased with increased sterilizations for 3.5-mm screws, whereas 2.0-mm screws were altered in pullout testing after 100 sterilizations. It is suspected that numerous sterilizations negatively alter the physical-mechanical properties of certain screw sizes. CLINICAL RELEVANCE The biomechanical properties of the bone-implant interface could negatively be affected by multiple steam sterilizations during clinical setting. [ABSTRACT FROM AUTHOR]

Study Design. A systematic review and meta-analysis. Objective. This study aims to compare pedicle screw accuracy, clinical outcomes, and complications between navigated and conventional techniques. Summary of Background Data. In the last decades, intraoperative navigation has been introduced in spinal surgery to prevent risks and complications. Materials and Methods. The search was executed on Cochrane Central Library, PubMed, and Scopus on April 30, 2023. Randomized controlled trials, prospective and retrospective studies that compared pedicle screw accuracy in the thoracic-lumbarsacral segments, blood loss, operative time, hospital stay, intraoperative and postoperative revision of screws, neurological and systemic complications, Visual Analogue Scale (VAS), and Oswestry Disability Index (ODI) between navigated and freehand or fluoroscopy-assisted techniques were included in this study. The meta-analysis was performed using Review Manager software. Clinical outcomes were assessed as continuous outcomes with mean difference, while pedicle screw accuracy and complications were assessed as dichotomous outcomes with odds ratio, all with 95% CIs. The statistical significance of the results was fixed at P<0.05. Results. This meta-analysis included 30 studies for a total of 17,911 patients and 24,600 pedicle screws. Statistically significant results in favor of the navigated technique were observed for the accuracy of pedicle screws (P= 0.0001), hospital stay (P= 0.0002), blood loss (P< 0.0001), postoperative revision of pedicle screws (P< 0.00001), and systemic complications (P= 0.0008). In particular, the positioning of the screws was clinically acceptable in 96.2% of the navigated group and 94.2% with traditional techniques. No significant differences were found in VAS, ODI, and operative time between the two groups. Conclusion. Navigated pedicle screw fixation has been demonstrated to be a safe and effective technique with high improvement in clinical outcomes and accuracy in patients undergoing spinal fusion compared with conventional techniques. [ABSTRACT FROM AUTHOR]

Thread shape is regarded as an important factor influencing the fixation strength and osseointegration of bone screws. However, commercial pedicle screws with a V-shaped thread are prone to generating stress concentration at the bone-screw interface, thereby increasing the risk of screw loosening. Thus, modification of the pedicle-screw thread is imperative. This study aimed to investigate the fixation stability of pedicle screws with the new undercut thread design in comparison to pedicle screws with a V-shaped thread. In vitro cadaveric biomechanical test and finite element analysis (FEA). Pedicle screws with the undercut thread (characterized by a flat crest feature and a tip-facing undercut feature) were custom-manufactured, whereas those with the V-shaped thread were procured from a commercial supplier. Fixation stability was assessed by the cyclic nonpullout compressive biomechanical testing on cadaveric female osteoporotic vertebrae. The vertical displacement and rotation angle of the 2 types of pedicle screws were calculated every 100 cycles to evaluate their resistance to migration and rotation. FEA was conducted to investigate the stress distribution and bone damage at the bone-screw interface for both types of pedicle screws. Biomechanical testing revealed that the pedicle screws with the undercut thread exhibited significantly lower vertical displacement and rotation angles than the pedicle screws with the V-shape thread (p <0.05). FEA results demonstrated a more uniform stress distribution in the bone surrounding the thread in the undercut design than in the V-shape design. Additionally, bone damage resulting from the pedicle screw was lower in the undercut design than in the V-shape design. Pedicle screws with an undercut thread are less prone to migration and rotation and thus more stable in the bone than those with a V-shape thread. The undercut thread design may reduce the incidence of pedicle-screw loosening. [ABSTRACT FROM AUTHOR]

Hydrothermal co-liquefaction (HTCL) is the prominent process for producing bio-products with a higher conversion rate. It is performed at high temperatures and pressure in the presence of water. Earlier, it was mostly conducted in batch reactors, but it has major limitations including operating volume, back mixing, and tedious process for high productivity. With that, the present investigation is performed on designing the screw shaft for the high-pressure HTCL process. The dimensional factors including flight length, pitch, helix angle, and depth were considered to design the optimal screw shaft. Likewise, principal stresses, shear stress, bending stress, bending moment, and total deformation were regarded as inevitable response variables to analyze the internal strength of the shaft. In this regard, the Taguchi approach provides the L9 (34) orthogonal array as an experimental design. Then, the numerical results from the transient structural analysis were analyzed with the assistance of statistical methods such as Grey Relational Grade (GRG), Grey Fuzzy Reasoning Grade, Analysis of Variance (ANOVA), and Taguchi method to find the most influential dimensions for minimizing the response variable. Consequently, the results from both GRG and Taguchi optimization were compared, and selected the most optimum parameters. [ABSTRACT FROM AUTHOR]

Objectives: To report the clinical experience and long‐term outcome following metabone fracture stabilisation using a commercially available micro‐plating system (VetKISS, 1.0‐mm, IMEX Veterinary, USA). Materials and Methods: Consecutive, client‐owned cats and dogs weighing <7 kg, with traumatic metabone fractures stabilised using VetKISS micro‐plates were prospectively enrolled with informed owner consent. Clinical and radiographic parameters were recorded. Either short‐term or long‐term clinical and radiographic follow‐up was required for study inclusion. Results: Four cats and six dogs were enrolled and operated by one of two board‐certified surgeons. Bodyweight ranged from 1.9 to 6.6 kg. Number of metabones fractured: all four (60%), three (30%) and two (10%). Anatomical alignment was restored for each metabone. External coaptation was not used in any case. Radiographic follow‐up documented clinical or bony union in all cases. Mean time to clinical union was 51 days. One major complication (screw removal) and two minor complications (partial construct failure) were observed. All patients made a complete functional recovery at the time of documented union. Long‐term follow‐up was available in five cases. No lameness (evaluated independently by both surgeons) or plate sensitivity was noted. Clinical Significance: This is the first clinical evaluation of the VetKISS for metabone fracture repair, and includes long‐term follow‐up. Results demonstrated complete functional recovery and 100% clinical union rates in all patients, with acceptable complication rates. This system can be considered for metabone repair in patients weighing <7 kg without the use of external coaptation. [ABSTRACT FROM AUTHOR]

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Broken screw removal from the implant connection is a common but challenging process. Several proposed methods and technical solutions may result in unsuccessful removal; thus, a novel, more conservative, risk-free method is proposed as a first attempt. The proposal is to use a silicon restoration holder to be twisted counterclockwise on the dried surface of the broken fragment inside the implant connection. This method, within the limitations of a minimal case series, yielded 100% results; however, despite previous attempts with less conservative techniques, this approach showed no efficacy. This article aims to promote the use of silicon restoration holders as a minimally invasive first attempt at broken screw retrieval treatment before considering other options. [ABSTRACT FROM AUTHOR]

To investigate the flexural failure mode and behavior of wooden beams strengthened using aluminum (Al) plates, which were attached with self-tapping screws and structural adhesive, ten specimens were tested in bending. The experimental parameters were the thickness of the bottom Al plate, the longitudinal and transverse grain spacing of the self-tapping screws. The experimental results revealed that (1) compared with unreinforced beams, the reinforced beams exhibited ultimate load capacity and displacement ductility coefficients that were 18.4%–54.3% and 6.4%–43.1% higher, respectively; (2) for the same Al plate thickness in the tensioned area, the initial stiffness of the reinforced wooden beams increases as the longitudinal grain spacing of the screw grains decreases; (3) the plane-section assumption was satisfied by the strain in the middle section of the Al plate-reinforced wooden beam along the height; (4) the strains at the same position in the wooden beam and Al plate were similar, thus indicating that the wooden beam and Al plate behaved collectively. Furthermore, a formula was proposed for calculating the flexural capacity of an Al plate-reinforced wooden beam, thus providing a valuable reference when designing wooden beam reinforcements. [ABSTRACT FROM AUTHOR]

Based on the principle of polymer field-synergistic plasticization, transportation and mixing, a field synergistic elongation element with a new structure of field-synergistic elongation screw was designed and developed for enhancing mixing and heat transfer. The ANSYS Polyflow was employed to numerically simulate ordinary double head threaded screws and field synergistic elongation screws with different elongation element arrangements. The effects of screw configuration on the mixing performance, heat transfer performance, and plasticization uniformity of polymeric rubber were comparatively analyzed. The results indicated that the comprehensive performance of the field synergy elongation element was superior to that of the ordinary threaded screw. Among these screws, the heat transfer performance of screw B with concentrated arrangement of field synergy elongation element was the best, and the mixing performance of screw F with the dispersed arrangement of field synergy elongation ele -ment was the best. The radial convergence channel of the elongation element in the field synergy elongation element changed the direction of the velocity field, generating radial components in the velocity vector. This promoted the synergistic interaction between the velocity field and the temperature gradient and velocity gradient fields, increasing the stretching flow and deformation in the flow field and strengthening the heat and mass transfer and transportation process. [ABSTRACT FROM AUTHOR]

A series of screw structures with different screw leads, outer diameters, and head numbers were established by using a modeling software. After the particle model was established and the contact parameters were set in the discrete element numerical simulation software, the conveying process of screw under different structures was simulated. The post-treatment module was used to analyze the force of particles in the conveying process and the mass flow rate at the outlet of the feeder, and the effect of screw structure on the feeding quality was discussed. The results indicated that the screw lead was the main factor affecting the conveying efficiency of the screw feeder. The conveying efficiency of the screw with the 20 mm lead was about 15 times as high as that with the 14mm lead; however, the discharging accuracy was reduced. The screw clearance is the main factor affecting the force of particles. The decrease of the clearance can lead to an increase in the force of particles. The average force of the screw clearance is about 1. 2×10-2 N. The double-headed screw caused the surge of force in the particle conveying process, resulting in a peak value of about 15 N. Meanwhile, the discharge efficiency was reduced, but the discharge stability was improved. [ABSTRACT FROM AUTHOR]

This paper investigates the die swell phenomenon in material extrusion additive manufacturing (MEX-AM) using customized 3D printing equipment with a co-rotating vertical twin-screw extrusion unit (Co-TSE AM). In twin-screw-based MEX-AM, the output rate is independent of the screws' rotational speed, and the complex die geometry impacts the thermomechanical behavior of the flow, thus affecting the die swell ratio (DSR). Towards exploring two premises, namely, influence of the Co-TSE AM die's complex geometry and influence of the main extrusion parameters, this study estimated the shear rate in the screws and die analytically and designed experiments to evaluate the effects of screw rotational speed, output rate, and nozzle diameter on the DSR. Scanning electron microscopy (SEM) assessed filament morphology and surface texture. The main results show DSR averages between 1.28 and 1.67 and both output rate and nozzle diameter significantly influence DSR, whereas screw rotational speed has no significant impact on the thermomechanical environment affecting material swelling. Filament width and height are differently influenced by standoff distance and print platform speed. The study enhances the understanding of the way extrusion parameters affect die swell in twin-screw MEX-AM, contributing to improved control and quality in single-step additive manufacturing processes. [ABSTRACT FROM AUTHOR]

The tightness and stability of the pipe connections are particularly important for pressurized environments. Pipe fittings are one of the most important subgroups of fittings. These fittings are not only used for connection purposes, but these fasteners may also have additional purposes such as sealing. In this study, a simulation model of the pipe fitting was created to evaluate the sealing performance. The obtained forces in the simulations were then used in the modified version of the classical bolt-tightening moment equation. In this equation, the additional parameter, R, is embedded. This parameter depends on the distance from the center (torque arm, x), slope parameter (k), and friction constant (S) between the body or nut and the ring parts. The consistency and applicability of the new equation were discussed by comparing the obtained results with the experimental results. It has been observed that there is a good agreement between the comparative results. [ABSTRACT FROM AUTHOR]

In this study, the operational conditions of a low‐cost in‐house‐built single screw filament extruder including operational parameters of extruder temperature (170–190°C) and screw speed (20–40 rpm) were evaluated in terms of the quality and dynamic‐mechanical properties of extruded PLA filaments. The designed experimental parameters were used to investigate the impact of operational parameters on filament diameter by Taguchi model where the predicted responses were evaluated. Results showed superior performance with R2 value of 0.9898. The measured filament diameters validated the predicted responses, and the error percentage was in the range of 0%–2.1%. Furthermore, in order to classify and distinguish filaments, we adept the artificial neural network (ANN) model classifier, and the measured dynamic mechanical analysis (DMA) values at certain temperatures were taken into consideration where the classes they belonged to be determined. Results reveal successful classification accuracy of filaments in the range of 94.82%–99.98% depends on different cases of classification process. [ABSTRACT FROM AUTHOR]

This paper delves into the historical evolution of spinal surgery, focusing on the pivotal role of the Harrington rod in treating spinal deformities. Introduced in 1955, the Harrington rod marked a significant breakthrough in neurosurgery, especially for scoliosis treatment, by offering a novel approach to spinal stabilization. Through a retrospective analysis, this study examines the development and impact of the Harrington rod, highlighting Dr. Paul Harrington's contributions to spinal surgery. His innovative technique revolutionized the management of spinal deformities, laying the groundwork for future advancements in spinal instrumentation. Despite initial skepticism, Harrington's methods gained acceptance, significantly influencing neurosurgical practices and patient outcomes. This study also explores subsequent advancements that built on Harrington's work, including the transition to long-segment spine constructs and the introduction of segmental pedicle screws, which allowed for more precise deformity correction. Reflecting on Harrington's legacy, this paper acknowledges the continuous evolution of spinal surgery, driven by the interplay between clinical challenges and technological innovations. Harrington's pioneering spirit exemplifies the ongoing pursuit of better surgical outcomes, underscoring the importance of innovation in the field of neurosurgery. [ABSTRACT FROM AUTHOR]

Ball screws are subjected to complex loads during machining processes, which affects the position accuracy of the feed shaft of machine tools. The lack of a reliable model for analyzing the deformation of the ball screw, coupled with the unclear relationship between the deformation of the ball screw and the position error of the feed shaft, makes it challenging to accurately predict and compensate for the position error. The objective of the present research is to investigate the correlation between the deformation of the ball screw and the position error of the feed shaft to improve the accuracy of the machine tool. First, this paper establishes a FEM model to explore the loading and deformation of the ball screw. Secondly, a method for predicting position errors based on the deformation of the ball screw is proposed. Finally, the ball screw-loading test device is used for the position error compensation experiment to verify the reliability of the prediction method. This paper serves as a reference for understanding the generation mechanism of position errors in machine tool feed systems. [ABSTRACT FROM AUTHOR]

This study focuses on long concrete interfaces tested under cyclic actions, fastened with post-installed industrial steel screws. The overall behavior and the effect of roughness were investigated in three long interfaces, representative of connections between, e.g., a slab and a wall, a beam and a wall, etc. The results were compared with those of short interfaces tested by the authors in previous campaigns. It was observed that rough long interfaces activate their maximum resistance at small values of imposed shear slip. When roughness was reduced, the maximum resistance was also reduced, the corresponding shear slip was increased, and the overall behavior was stable. For large values of the shear slip, imposed at one end of the interface, the shear slips along it tended to be uniform, both in short and long interfaces. The limited embedment length of the screws led to their pronounced pullout. Finally, the asymmetry of resistance between the two loading directions that was observed in short interfaces was alleviated in the long ones, where also the scatter of the results was limited among duplicate specimens. [ABSTRACT FROM AUTHOR]

In continuous powder handling processes, precise and consistent feeding is crucial for ensuring the quality of the final product. The intermixing effect caused by agitators, which alters the powder's bulk density, flow rate, and flow patterns, plays a significant role in this process, yet it is often overlooked. This study combines discrete element method (DEM) modeling and experiments using a commercial-scale feeder to propose a Digital Twin (DT) framework. The DEM model accurately captures key flow features, such as bypass trajectories, stagnant zones, and preferential flow patterns, while providing quantitative predictions for the feed factor and zones prone to material accumulation. Scenario analysis is performed to identify the most favorable operating ranges of the screw-agitator ratio and screw speed, considering the cohesive properties of the powder. The study demonstrates that powders with poor flow characteristics require tighter operational constraints, as the screw-agitator ratio is susceptible to variations in mass feed rate. This contribution highlights the importance of selecting an appropriate screw-agitator ratio instead of maintaining a fixed value. Properly choosing this ratio helps determine an optimal operation window, which aims to achieve a minimum agitation level needed to induce unhindered flow and reduce variability in the mass flow rate. [ABSTRACT FROM AUTHOR]

Objective Methods Results Conclusion Imperfect fitting of the navigation template leads to prolonged surgery time and increased blood loss. These problems have not been effectively addressed in previous research. This study explores the efficacy of a novel 5‐point positioning point‐contact pedicle navigation template in complex pedicle situations in scoliosis.This study employed a retrospective controlled design. From November 2019 to November 2023, 28 patients with scoliosis and complex pedicle were selected and underwent scoliosis correction surgery. A 5‐point positioning point‐contact pedicle navigation template was used intraoperatively to guide pedicle screw placement. Matched with 56 historical cases as a control group. The analysis included screw placement time, screw placement bleeding volume, fluoroscopy frequency, manual repositioning frequency, screw placement accuracy and grade, screw placement complications, and main curve correction rate. Continuous variables were compared using the independent samples t‐test. Categorical data were analyzed with the chi‐square test.All 28 patients successfully underwent surgery, with a total of 268 pedicle screws placed. The surgery duration ranged from 220 to 410 min, with an average of (283.16 ± 51.26) min. Intraoperative blood loss ranged from 630 to 1900 mL, with an average of (902.17 ± 361.25) mL. Pedicle screw placement time ranged from 60 to 130 min, with an average of (85.24 ± 24.65) min. Pedicle screw placement bleeding volume ranged from 40 to 180 mL, with an average of (76.47 ± 42.65) mL. Fluoroscopy frequency ranged from 3 to 7 times, with an average of (4.31 ± 1.14) times. Manual repositioning frequency ranged from 0 to 2 times, with an average of (0.46 ± 0.58) times. Pedicle screw placement grades: Grade I: 237 screws; Grade II: 25 screws; Grade III: 6 screws; Grade IV: 0 screws. There were no screw‐related complications. The correction rate ranged from 46% to 68%, with an average of (55.83 ± 9.22)%. Compared to the experienced screw group, the differences in screw placement time, screw placement bleeding volume, fluoroscopy procedures, and manual redirections were statistically significant (p < 0.05).The 5‐point positioning point‐contact pedicle navigation template features a claw‐like structure that securely adapts to various deformed vertebral facet joints, avoiding drift phenomena and ensuring accurate screw placement. Its pointed contact structure with the lamina of the spine avoids extensive and complete detachment of posterior structures, reducing blood loss, surgery time, and trauma. Predesigned pedicle screw entry points and directions reduce fluoroscopy frequency and surgery time. [ABSTRACT FROM AUTHOR]

Statement of problem: The demand for immediate implant placement (IIP) in the esthetic zone is rapidly increasing. Despite the treatment's benefits, the sagittal root position often dictates implant angulation, commonly necessitating the use of cement-retained restorations. This study investigates the impact of angulated screw channel on IIP in the esthetic zone. Purpose: The purpose of this cone-beam computed tomography (CBCT) study was to determine the probability of IIP in the esthetic zone, using four different implant angulations. Materials and methods: A retrospective review of CBCT images was conducted and accessed on 9 June 2021. The midsagittal images of maxillary anterior teeth were input into an implant planning software (Implant Studio®). Bone Level X Straumann® implant (BLX 3.5, 3.75, 4.0, 4.5, 5.0 mm) and Bone Level Tapered implant (BLT 2.9, 3.3 mm) were selected for 3D implant planning of IIP in the esthetic zone. The frequency distribution and probability of IIP were recorded and compared among all maxillary anterior teeth. Results: CBCT images from 720 teeth (120 patient) were evaluated, revealing an overall probability of IIP in the esthetic zone is 76.11% (548/720). Different implant restoration type was evaluated in this study, with the following results; straight screw-retained prosthesis at 3.47% (19/548), cement-retained prosthesis at 14.59% (80/548) and angle screw-retained prosthesis at 85.40% (468/548). Conclusion: IIP with traditional straight screw-retained prosthesis demonstrated the lowest probability. Nevertheless, the use of angulated screw channels enhances the probability of achieving straight screw-retained prostheses. Clinical implications: The angulated screw channel is essential for increasing the probability of screw-retained prosthesis in IIP in the esthetic zone. However, limitation in screw angle correction still necessitate the use of cement-retained prostheses for numbers of patients undergoing IIP. [ABSTRACT FROM AUTHOR]

The masonry veneer wall system relies on metal wall ties to connect the outer masonry leaf to the internal frame, ensuring structural stability. In Australia, a masonry veneer wall typically consists of a timber frame that has galvanised wall ties fixed to the side of the timber studs, with a nail or screw, spanned across an air cavity to the external leaf of masonry. This study explores the impact of corrosion on the integrity of these wall ties, emphasising their susceptibility to failure during extreme events. Existing literature highlights tension failure in a veneer wall is the result of nail pull-out from the timber. In the current research, accelerated corrosion of an R2 (Z600) wall tie reveals that tensile strength reduction is due to decreasing tie cross section from corrosion, leading to wall tie fracture rather than nail pull-out. Understanding these failure mechanisms is crucial for building assessment and monitoring strategies for masonry structures, especially in regions prone to extreme wind or seismic activity in combination with corrosion susceptibility, such as coastal environments. [ABSTRACT FROM AUTHOR]

Objective: To propose a screw algorithm and investigate the anatomical feasibilities and clinical outcomes of five distinct fixation methods for C2-3 fused vertebra with high-ridding vertebral arteries (VA) (HRVA) when the C2 pedicle screw placement is unfeasible. Methods: Thirty surgical patients with congenital C2-3 fusion, HRVA, and atlantoaxial dislocation (AAD) were included. We designed a algorithm for alternative screw implantation into C2-3 fused vertebrae, including C2 pedicle screw with in-out-in (passing VA groove) technique (in-out-in screw), subfacetal screw, translaminar screw, lateral mass screw, C3 pedicle screw. VA diameter and position, C2 and C3 pedicles, superior facets, fused lamina, and fused lateral mass dimensions were evaluated for screw implantation indication. Implant failure, reduction loss, implant placement accuracy were investigated by computed tomography. Results: A total of 5 VAs were identified as distant VAs; a total of 2 VAs were categorized as occlusive VAs. Sufficient dimension of lateral mass and lamina provided the broadest indications for screw implantation, while the distant or occlusive VA provided the most limited indications for in-out-in screw. The indications of five alternative methods ranged from narrowest to widest as follows: in-out-in screw, C3 pedicle screw, subfacetal screw, translaminar screw, lateral mass screw. The translaminar screws and the lateral mass screws increased the probability of implant failure. All patients who received in-out-in screws, C3 pedicle screws, and subfacetal screws achieved fusion. The accuracy ranged from lowest to highest as follows: C3 pedicle screw, lateral mass screw, in-out-in screw, subfacetal screw, translaminar screw. No translaminar screws deviated. Conclusions: The algorithm proved to be a valuable tool for screw selection in cases of C2-3 fused vertebrae with HRVAs. The subfacetal screw, boasting broad indications, a high fusion rate, and exceptional accuracy, stood as the primary preferred alternative. [ABSTRACT FROM AUTHOR]

This paper provides a compact, noncontiguous, high isolation, manifold triplexer operating from 25.8 to 49.5 GHz, a 62.95% wide fractional operating bandwidth. The triplexer is composed of three waveguide bandpass filters with Chebyshev responses. The initialization and loop optimization strategy of the triplexer are given. To eliminate undesired high‐order mode transmission between common port and filters, ridged‐waveguide topology, tuning screws, capacitive windows, and narrowing the wide edges of resonant cavities for the third filter are employed. The measured results and simulated ones are in good agreement. To our knowledge, this is the most broadband, high‐power triplexer demonstrated to date. [ABSTRACT FROM AUTHOR]

(1) Background: Our team has previously introduced the Single-Step Pedicle Screw System (SSPSS), which eliminates the need for K-wires, as a safe and effective method for percutaneous minimally invasive spine (MIS) pedicle screw placement. Despite this, there are ongoing concerns about the reliability and accuracy of screw placement in MIS procedures without traditional tools like K-wires and Jamshidi needles. To address these concerns, we evaluated the accuracy of the SSPSS workflow by comparing the planned intraoperative screw trajectories with the final screw positions. Traditionally, screw placement accuracy has been assessed by grading the final screw position using postoperative CT scans. (2) Methods: We conducted a retrospective review of patients who underwent lumbar interbody fusion, using intraoperative 3D navigation for screw placement. The planned screw trajectories were saved in the navigation system during each procedure, and postoperative CT scans were used to evaluate the implanted screws. Accuracy was assessed by comparing the Gertzbein and Robbins classification scores of the planned trajectories and the final screw positions. Accuracy was defined as a final screw position matching the classification of the planned trajectory. (3) Results: Out of 206 screws, 196 (95%) were accurately placed, with no recorded complications. (4) Conclusions: The SSPSS workflow, even without K-wires and other traditional instruments, facilitates accurate and reliable pedicle screw placement. [ABSTRACT FROM AUTHOR]

High-resolution imagery captured by drones can detect critical components on high-voltage transmission towers, providing inspection personnel with essential maintenance insights and improving the efficiency of power line inspections. The high-resolution imagery is particularly effective in enhancing the detection of fine details such as screws. The QYOLO algorithm, an enhancement of YOLOv8, incorporates context queries into the feature pyramid, effectively capturing long-range dependencies and improving the network's ability to detect objects. To address the increased network depth and computational load introduced by query extraction, Ghost Separable Convolution (GSConv) is employed, reducing the computational expense by half and further improving the detection performance for small objects such as screws. The experimental validation using the Transmission Line Accessories Dataset (TLAD) developed for this project demonstrates that the proposed improvements increase the average precision (AP) for small objects by 5.5% and the F1-score by 3.5%. The method also enhances detection performance for overall targets, confirming its efficacy in practical applications. [ABSTRACT FROM AUTHOR]

Introduction: Degenerative spondylolisthesis causes translational and angular malalignment, resulting in a loss of segmental lordosis. This leads to compensatory adjustments in adjacent levels to maintain balance. Lateral lumbar interbody fusion (LLIF) and transforaminal lumbar interbody fusion (TLIF) are common techniques at L4-5. This study compares compensatory changes at adjacent L3-4 and L5-S1 levels six months post LLIF versus TLIF for grade 1 degenerative spondylolisthesis at L4-5. Methods: A retrospective study included patients undergoing L4-5 LLIF or TLIF with posterior pedicle screw instrumentation (no posterior osteotomy) for grade 1 spondylolisthesis. Pre-op and 6-month post-op radiographs measured segmental lordosis (L3-L4, L4-L5, L5-S1), lumbar lordosis (LL), and pelvic incidence (PI), along with PI-LL mismatch. Multiple regressions were used for hypothesis testing. Results: 113 patients (61 LLIF, 52 TLIF) were studied. TLIF showed less change in L4-5 lordosis (mean = 1.04°, SD = 4.34) compared to LLIF (mean = 4.99°, SD = 5.53) (p = 0.003). L4-5 angle changes didn't correlate with L3-4 changes, and no disparity between LLIF and TLIF was found (all p > 0.16). In LLIF, greater L4-5 lordosis change predicted reduced compensatory L5-S1 lordosis (p = 0.04), while no significant relationship was observed in TLIF patients (p = 0.12). Conclusion: LLIF at L4-5 increases lordosis at the operated level, with compensatory decrease at L5-S1 but not L3-4. This reciprocal loss at adjacent L5-S1 may explain inconsistent improvement in lumbar lordosis (PI-LL) post L4-5 fusion. [ABSTRACT FROM AUTHOR]

Objectives: Single position lateral fusion with robotic assistance eliminates the need for surgical staging while harnessing the precision of robotic adjuncts. We expand on this technique by demonstrating the technical feasibility of placing bilateral pedicle screws with S2-alar-iliac (S2AI) fixation while in the lateral position. Methods: A cadaveric study was performed using 12 human specimens. A retrospective clinical series was also performed for patients who had undergone robot-assisted placement of S2AI screws in lateral decubitus between June 2020 and June 2022. Case demographics, implant placement time, implant size, screw accuracy, and complications were recorded. Early postoperative radiographic outcomes were reported. Results: In the cadaveric series, a total of 126 screws were placed with robotic assistance in 12 cadavers of which 24 screws were S2AI. There were four breaches from pedicle screws and none with S2AI screws for an overall accuracy rate of 96.8%. In the clinical series, four patients (all male, mean age 65.8 years) underwent single position lateral surgery with S2AI distal fixation. Mean BMI was 33.6 and mean follow-up was 20.5 months. Mean radiographic improvements were lumbar lordosis 12.3 ± 4.7°, sagittal vertical axis 1.5 ± 2.1 cm, pelvic tilt 8.5 ± 10.0°, and pelvic incidence—lumbar lordosis mismatch 12.3 ± 4.7°. A total of 42 screws were placed of which eight screws were S2AI. There were two breaches from pedicle screws and none from S2AI screws for an overall accuracy rate of 95.2%. No repositioning or salvage techniques were required for the S2AI screws. Conclusions: We demonstrate here the technical feasibility of single position robot-assisted placement of S2-alar-iliac screws in the lateral decubitus position for single position surgery. [ABSTRACT FROM AUTHOR]

Purpose: Minimally invasive single position lateral ALIF at L5-S1 with simultaneous robot-assisted posterior fixation has technical and anatomic considerations that need further description. Methods: This is a retrospective case series of single position lateral ALIF at L5-S1 with robotic assisted fixation. End points included radiographic parameters, lordosis distribution index (LDI), complications, pedicle screw accuracy, and inpatient metrics. Results: There were 17 patients with mean age of 60.5 years. Eight patients underwent interbody fusion at L5-S1, five patients at L4-S1, two patients at L3-S1, and one patient at L2-S1 in single lateral position. Operative times for 1-level and 2-level cases were 193 min and 278 min, respectively. Mean EBL was 71 cc. Mean improvements in L5-S1 segmental lordosis were 11.7 ± 4.0°, L1-S1 lordosis of 4.8 ± 6.4°, sagittal vertical axis of − 0.1 ± 1.7 cm°, pelvic tilt of − 3.1 ± 5.9°, and pelvic incidence lumbar–lordosis mismatch of − 4.6 ± 6.4°. Six patients corrected into a normal LDI (50–80%) and no patients became imbalanced over a mean follow-up period of 14.4 months. Of 100 screws placed in lateral position with robotic assistance, there were three total breaches (two lateral grade 3, one medial grade 2) for a screw accuracy of 97.0%. There were no neurologic, vascular, bowel, or ureteral injuries, and no implant failure or reoperation. Conclusion: Single position lateral ALIF at L5-S1 with simultaneous robotic placement of pedicle screws by a second surgeon is a safe and effective technique that improves global alignment and lordosis distribution index. [ABSTRACT FROM AUTHOR]

The present endeavour numerically exploits the use of a phase-field model to simulate and investigate fracture patterns, deformation mechanisms, damage, and mechanical responses in a human vertebra after the incision of pedicle screws under compressive regimes. Moreover, the proposed phase field framework can elucidate scenarios where different damage patterns, such as crack nucleation sites and crack trajectories, play a role after the spine fusion procedure, considering several simulated physiological movements of the vertebral body. Spatially heterogeneous elastic properties and phase field parameters have been computationally derived from bone density estimation. A convergence analysis has been conducted for the vertebra-screws model, considering several mesh refinements, which has demonstrated good agreement with the existing literature on this topic. Consequently, by assuming different angles for the insertion of the pedicle screws and taking into account a few vertebral motion loading regimes, a plethora of numerical results characterizing the damage occurring within the vertebral model has been derived. Overall, the phase field results confirm and enrich the current literature, shed light on the medical community, which will be useful in enhancing clinical interventions and reducing post-surgery bone failure and screw loosening. The proposed computational approach also investigates the effects in terms of fracture and mechanical behaviour of the vertebral-screws body within different metastatic lesions opening towards major life threatening scenarios. [ABSTRACT FROM AUTHOR]

This article addresses manufacturing structures made via injection molding from biodegradable materials. The mentioned structures can be successfully used as energy-absorbing liners of all kinds of sports helmets, replacing the previously used expanded polystyrene. This paper is focused on injection technological tests and tensile tests (in quasi-static and dynamic conditions) of several composites based on a PLA matrix with the addition of other biodegradable softening agents, such as PBAT and TPS (the blends were prepared via melt blending using a screw extruder with mass compositions of 50:50, 30:70, and 15:85). Tensile tests showed a positive strain rate sensitivity of the mixtures and a dependence of the increase in the ratio of the dynamic to static yield stress on the increase in the share of the plastic component in the mixture. Technological tests showed that increasing the amount of the plasticizing additive by 35% (from 50% to 85%) results in a decrease in the minimal thickness of the thin-walled element that can be successfully injection molded by about 32% in the case of PLA/PBAT blends (from 0.22 mm to 0.15 mm) and by about 26% in the case of PLA/TPS blends (from 0.23 mm to 0.17 mm). Next, the thin-walled elements (dimensions of 55 × 55 × 20 mm) were manufactured and evaluated using a spring-loaded drop hammer. The 60 J impact energy was tested in accordance with the EN 1078 standard. The dynamic crushing test included checking the influence of the materials' temperature (−20, 0, 20, and 40 °C) and the impact velocity. It was proven that the maximum deflection increases with increasing material temperature and an increase in the share of the plastic component in the mixture. The PLA15PBAT85 blend was selected as the most effective material in terms of its use as an energy-absorbing liner for sport helmets. Johnson–Cook and Cowper–Symonds material plasticizing models were constructed. Their use during dynamic FE simulation provided results that were in good agreement with those of the conducted experiment. [ABSTRACT FROM AUTHOR]

The study investigates how cage positions in oblique lumbar interbody fusion (OLIF) combined with posterior percutaneous pedicle screw internal fixation (PPSF) affect lumbar canal and foraminal decompression and postoperative outcomes, providing guidance for optimal placement and efficacy assessment. This investigation assesses radiologic outcomes and follow-up data in relation to cage position variability among 80 patients who underwent L4/5 single-segment OLIF + PPSF from 2018 to 2022. In the study involving 80 participants, the combination of OLIF and PPSF significantly improved lower back and leg symptoms in patients, leading to positive clinical outcomes during follow-up. The intervertebral disk height increased from an average of 8.10 ± 2.79 mm before surgery to 11.75 ± 2.14 mm after surgery (P < 0.001). Additionally, this surgical technique notably increased the FH (P < 0.001) and expanded the DCSA from 68.81 ± 53.89 mmˆ2 before surgery to 102.91 ± 60.46 mmˆ2 after surgery (P < 0.001). Linear results suggest that changes in the position of the cage do not affect spinal imaging parameters. There is no significant difference in the correction of spinal parameters or prognosis whether the cage is back, middle, ahead. In the OLIF + PPSF procedure, strict requirements for cage position are not necessary to achieve predetermined spinal biomechanical parameters. The practice of repeated fluoroscopy to adjust cage position postimplantation does not provide added clinical benefits to the patient. [ABSTRACT FROM AUTHOR]

Surgical management of lumbar spondylolisthesis requires neural decompression, stabilization, and alignment restoration. Minimally invasive spine approaches offer a wide variety of advantages for spondylolisthesis management. This intraoperative note describes the treatment of L4-L5 lumbar spondylolisthesis with lateral lumbar interbody fusion (LLIF) and percutaneous pedicle screw fixation (PSF). The surgical technique for treating L4-L5 lumbar spondylolisthesis using a minimally invasive approach with LLIF and percutaneous PSF is described. This operative technique is illustrated with figures, and an intraoperative case example of its application is described. LLIF with percutaneous PSF can be a safe, effective, and reliable option for treating lumbar spondylolisthesis when applied with appropriate surgical technique in a selected patient population. This technique is a valuable addition to the range of available spine surgical options. LLIF with percutaneous PSF can be an effective technique for treating lumbar L4-L5 spondylolisthesis. [ABSTRACT FROM AUTHOR]

Objective: To compare the functional and radiological outcomes of treatment of volar Barton’s fractures using T plate with and without distal end screws. Methods: This randomized control trial was conducted at the department of Orthopedics, Mayo Hospital, Lahore, Pakistan from December 2021 to May 2022. Total 60 patients (30 in each group) were randomly allocated to either group A (T-Plate with distal end screws) or B (T-Plate without distal end screws). Patients were followed up on day-0, day-14, day-28 and day-90. Assessments of patients were done by Green O’Brien Score for pain, Modified Warden Score for callus formation on radiographs at 12-weeks of follow-up and Stewart Score for displacement of fracture. Results: At 90th day, significant difference was seen in Green O’Brien Score (Excellent score: Group-A: 80% vs. Group-B: 90%, p=0.278) while Stewart scores remained comparable (Excellent Score: Group-A: 93.33% vs. Group-B: 96.67%, p=0.221) between treatment groups. Fracture healing assessed with Modified Warden score for score 4 did not show significant difference between both groups at 90th day. i.e. (Group-A: 96.67% vs. Group-B: 96.67%). However, callus formation assessed with Modified Warden score for score 3 showed significant differences between groups at 90th day. i.e. (Group-A: 53.33% vs. Group-B: 86.67%, p=0.001). Conclusion: Both treatment approaches appear to yield comparable outcomes in terms of clinical assessment, Stewart scores, and fracture healing, with a potential advantage for T-plate without distal end screw in callus formation at the 90th day. [ABSTRACT FROM AUTHOR]