Transverse Angle Research Articles

Dissimilar unbeveled aluminum to steel butt joint achieved by laser-arc hybrid welding-brazing

In this study, unbeveled butt joints of 2 mm thick steel and aluminum plates were welded using a laser-arc hybrid process. The influence of welding speed and wire feed speed on joint weld formation, microstructures, and mechanical properties were investigated. The results indicate that using a laser-arc hybrid heat source enables good weld formation of steel/aluminum dissimilar metals without groove preparation, even under high welding speed conditions. The steel side interface formed Fe₂(Al,Si)₅ near the steel and Fe(Al,Si)₃ near the aluminum. As the welding heat input decreased, the thickness of the intermetallic compounds gradually reduced. With an increase in welding speed or wire feed speed, the tensile strength of the joint first increased and then decreased, reaching a maximum of 104.47 MPa. Cracks propagated rapidly along the intermetallic compound region, resulting in brittle fracture characteristics. The three-point bending test showed a maximum longitudinal bending angle of 53.82° and a maximum transverse bending angle of 36.54°.

Development and Validation of Deep Learning Preoperative Planning Software for Automatic Lumbosacral Screw Selection Using Computed Tomography

Achieving precise pedicle screw placement in posterior lumbar interbody fusion (PLIF) is essential but difficult due to the intricacies of manual preoperative planning with CT scans. We analyzed CT data from 316 PLIF patients, using Mimics software for manual planning by two surgeons. A deep learning model was trained on 228 patients and validated on 88 patients, assessing planning efficiency and accuracy. Automatic planning successfully segmented and placed screws in all 316 cases, significantly outperforming manual planning in speed. The Dice coefficient for segmentation accuracy was 0.95. The difference in mean pedicle transverse angle (PTA) and pedicle sagittal angle (PSA) for automatic planning screws compared to manual planning screws was 1.63 ± 0.83° and 1.39 ± 1.03°, respectively, and these differences were either statistically comparable or not significantly different compared to the variability of manual planning screws. The average Dice coefficient of implanted screws was 0.63 ± 0.08, and the consistency between automatic screws and manual reference screws was higher than that of internal screws (Dice 0.62 ± 0.09). Compared with manual screws, automatic screws were shorter (46.58 ± 3.09 mm) and thinner (6.24 ± 0.35 mm), and the difference was statistically significant. In qualitative validation, 97.7% of the automatic planning screws were rated Gertzbein–Robbins (GR) Class A and 97.3% of the automatic planning screws were rated Badu Class 0. Deep learning software automates lumbosacral pedicle screw planning, enhancing surgical efficiency and accuracy.

Detecting Patient Position Using Bed-Reaction Forces for Pressure Injury Prevention and Management

A key best practice to prevent and treat pressure injuries (PIs) is to ensure at-risk individuals are repositioned regularly. Our team designed a non-contact position detection system that predicts an individual’s position in bed using data from load cells under the bed legs. The system was originally designed to predict the individual’s position as left-side lying, right-side lying, or supine. Our previous work suggested that a higher precision for detecting position (classifying more than three positions) may be needed to determine whether key bony prominences on the pelvis at high risk of PIs have been off-loaded. The objective of this study was to determine the impact of categorizing participant position with higher precision using the system prediction F1 score. Data from 18 participants was collected from four load cells placed under the bed legs and a pelvis-mounted inertial measurement unit while the participants assumed 21 positions. The data was used to train classifiers to predict the participants’ transverse pelvic angle using three different position bin sizes (45°, ~30°, and 15°). A leave-one-participant-out cross validation approach was used to evaluate classifier performance for each bin size. Results indicated that our prediction F1 score dropped as the position category precision was increased.

Cardiac diffusion-weighted and tensor imaging: a Society for Cardiovascular Magnetic Resonance (SCMR) special interest group consensus statement

Thanks to recent developments in Cardiovascular magnetic resonance (CMR), cardiac diffusion-weighted magnetic resonance is fast emerging in a range of clinical applications. Cardiac diffusion-weighted imaging (cDWI) and diffusion tensor imaging (cDTI) now enable investigators and clinicians to assess and quantify the 3D microstructure of the heart. Free-contrast DWI is uniquely sensitized to the presence and displacement of water molecules within the myocardial tissue, including the intra-cellular, extra-cellular and intra-vascular spaces. CMR can determine changes in microstructure by quantifying: a) mean diffusivity (MD) –measuring the magnitude of diffusion; b) fractional anisotropy (FA) – specifying the directionality of diffusion; c) helix angle (HA) and transverse angle (TA) –indicating the orientation of the cardiomyocytes; d) E2A and E2A mobility – measuring the alignment and systolic-diastolic mobility of the sheetlets, respectively.This document provides recommendations for both clinical and research cDWI and cDTI, based on published evidence when available and expert consensus when not. It introduces the cardiac microstructure focusing on the cardiomyocytes and their role in cardiac physiology and pathophysiology. It highlights methods, observations and recommendations in terminology, acquisition schemes, post-processing pipelines, data analysis and interpretation of the different biomarkers. Despite the ongoing challenges discussed in the document and the need for ongoing technical improvements, it is clear that cDTI is indeed feasible, can be accurately and reproducibly performed and, most importantly, can provide unique insights into myocardial pathophysiology.

The effect of Scheuermann's kyphosis on rib cage morphology: A skeletal study

BackgroundEvolutionary changes in human rib cage morphology rendered it prone to pathologies like Scheuermann's kyphosis (SK). However, the impact of SK on rib cage morphology is unclear. PurposeThis study aimed to examine differences in rib cage morphology (e.g., ribs and sternum) between SK patients and a control group. MethodsMeasurements of the vertebral body, transverse process angle, sternum, and rib size were taken from the skeletons of SK patients (76) and a control group (96). Statistical tests were carried out to examine differences between the study and control groups and between the right and left sides. Correlations were obtained to examine the associations between the extent of the kyphosis (kyphosis angle) and rib cage variables. ResultsThe SK group yielded significantly longer and flatter ribs than the control group in both sexes. However, males had the largest differences in the 9th rib and females in the upper ribs (5-7). Inconsistency in symmetry results was found between the sexes. In summary, SK patients had a larger anteroposterior diameter in relation to the transverse diameter than the control group. Discussion and ConclusionsSK affects the morphology of the entire thorax and changes rib proportions similarly in males and females. These changes might have a role in bipedal stability and locomotion efficiency. Moreover, understanding the unique anatomy of SK patients is essential when performing an anterior release and anterior fusion operative approach. Finally, it provides insights into respiratory complications and poor prognosis related to individuals suffering from severe hyperkyphosis.

Multiscale Fiber Remodeling in the Infarcted Left Ventricle using a Stress-Based Reorientation Law

The organization of myofibers and extra cellular matrix within the myocardium plays a significant role in defining cardiac function. When pathological events occur, such as myocardial infarction (MI), this organization can become disrupted, leading to degraded pumping performance. The current study proposes a multiscale finite element (FE) framework to determine realistic fiber distributions in the left ventricle (LV). This is achieved by implementing a stress-based fiber reorientation law, which seeks to align the fibers with local traction vectors, such that contractile force and load bearing capabilities are maximized. By utilizing the total stress (passive and active), both myofibers and collagen fibers are reoriented. Simulations are conducted to predict the baseline fiber configuration in a normal LV as well as the adverse fiber reorientation that occurs due to different size MIs. The baseline model successfully captures the transmural variation of helical fiber angles within the LV wall, as well as the transverse fiber angle variation from base to apex. In the models of MI, the patterns of fiber reorientation in the infarct, border zone, and remote regions closely align with previous experimental findings, with a significant increase in fibers oriented in a left-handed helical configuration and increased dispersion in the infarct region. Furthermore, the severity of fiber reorientation and impairment of pumping performance both showed a correlation with the size of the infarct. The proposed multiscale modeling framework allows for the effective prediction of adverse remodeling and offers the potential for assessing the effectiveness of therapeutic interventions in the future. Statement of SignificanceThe organization of muscle and collagen fibers within the heart plays a significant role in defining cardiac function. This organization can become disrupted after a heart attack, leading to degraded pumping performance. In the current study, we implemented a stress-based fiber reorientation law into a computer model of the heart, which seeks to realign the fibers such that contractile force and load bearing capabilities are maximized. The primary goal was to evaluate the effects of different sized heart attacks. We observed substantial fiber remodeling in the heart, which matched experimental observations. The proposed computational framework allows for the effective prediction of adverse remodeling and offers the potential for assessing the effectiveness of therapeutic interventions in the future.

Interlaboratory Study Toward Combining Gait Kinematics Data Sets of Long-Distance Runners.

The limited sample size in gait studies has hampered progress in the field. This challenge could be addressed through multicenter studies, thereby leveraging data sets from different laboratories. This study compared 3-dimensional lower-extremity running kinematics between the Biomechanics and Motor Control Laboratory, Federal University of ABC (Brazil), and the Running Injury Clinic, University of Calgary (Canada). Three-dimensional lower-extremity kinematics from 23 male runners were collected from each laboratory using comparable instrumentation and experimental procedures. The 3-dimensional hip, knee, and ankle angles were compared within and between centers using root-mean-square deviation. Two-sample t tests Statistical Parametric Mapping tested the hypothesis that the data from both laboratories were not different. The sagittal plane hip, knee, and ankle angles were similar between laboratories, while notable differences were observed for frontal (hip and ankle) and transverse (hip and knee) plane angles. The average interlaboratory root-mean-square deviation (2.6°) was lower than the intralaboratory root-mean-square deviation (Biomechanics and Motor Control = 4.8°, Running Injury Clinic = 5.6°), with the ankle transverse angle displaying the smallest, and the knee transverse angle displaying the largest variability. This study demonstrates the potential of combining gait kinematics data from different laboratories to increase sample size, but frontal and transverse plane data should be considered with caution.

The Effect of Static Trial on Knee Adduction Moment During Walking.

Background and aim Sophisticated technologies in rehabilitation, such as three-dimensional gait analysis, allow for measuring kinematic and kinetic variables while performing activities. The first peak external knee adduction moment (EKAM) is considered an important outcome in individuals with knee osteoarthritis (OA) and has been shown to be affected by changes in foot position in static trials. The present study aimed to explore the variables in static trials that may lead to changes in the value of the EKAM while walking. Methods Twelve individuals participated in the current study and were asked to perform three static trials as follows: 20° toe-out, straight (0°), and 20° toe-in. The participants were asked to walk five trials (their own shoes and paces). The first peak EKAM was the main study outcome and was compared between conditions. Linear regression was used to investigate which variables in the static trials significantly predicted the magnitude of change in the EKAM while walking. Results The first peak EKAM significantly decreased by 8.2% while walking when changing the foot position in static trials from 20° toe-in to 20° toe-out. The magnitude of change in the EKAM was significantly (p<0.01) predicted by the magnitude of change in the knee joint frontal plane angle, shank transverse plane angle, ankle joint frontal plane angle, and hip joint frontal plane angle during static trials between 20° toe-in and 20° toe-out. The model was able to predict 94% of the variation in the EKAM due to changes in foot position during static trials. Conclusion Modifications in foot position during static trials led to a change in the first peak EKAM while walking. Researchers should focus on controlling the knee joint frontal plane angle, shank transverse plane angle, ankle joint frontal plane angle, and hip joint frontal plane angle during static trials when conducting longitudinal or crossover studies. Controlling these variables is necessary to reduce the likelihood of the EKAM being affected by static trials and to ensure that the EKAM changes in dynamic trials are not masked or increased by static trials.

Frontal and transverse plane hip angles during walking vary between CGM2 and Plug-in-Gait models

Frontal and transverse plane hip angles during walking vary between CGM2 and Plug-in-Gait models

Analysis of the Suitability of Ultrasonic Testing for Verification of Nonuniform Welded Joints of Austenitic-Ferritic Sheets.

The purpose of the presented research was to determine the suitability of using ultrasonic testing (UT) to inspect heterogeneous, from a material point of view, welded joints on the example of the joints of a ferritic steel element with elements made of an austenitic steel. The echo technique with transverse (SEK) and longitudinal wave heads (SEL) addressed this issue. Due to the widespread use of 13CrMo4-5 and X2CrNiMo17-12-2 steel grades in the energy industry, they were selected as the test materials for the study. The objects of the presented research were welded joint specimens with thicknesses of 8, 12, and 16 mm and dimensions of 300 × 300 mm, made using the 135 metal active gas (MAG) process with the use of the Lincoln 309LSi wire-a ferritic-austenitic filler material. The stages of the research task were (1) making distance-amplitude curve (DAC) patterns from the test materials; (2) preparation of specimens of welded joints with artificial discontinuities in the form of through-holes; (3) performing UT tests on welded joints with artificial discontinuities using heads with 60° and 70° angles for the transverse wave and angle heads for longitudinal waves with similar beam insertion angles; (4) selection, by radiographic testing (RT), of welded joint specimens with natural discontinuities in the form of a lack of sidewall fusion; (5) performing UT tests on welded joints with natural discontinuities, using heads as welded joints with artificial discontinuities. It was found that (1) the highest sensitivity of discontinuity detection was obtained by performing tests on the ferritic steel side, which is due to the lower attenuation of the ultrasonic wave propagating in ferritic steel compared to austenitic steel; (2) the best detection of discontinuities could be obtained using a longitudinal ultrasonic wave; (3) there is a relationship between the thickness of the welded elements, the angle of the ultrasonic beam introduction, and the effectiveness of discontinuity detection.

Morphological changes in flatfoot: a 3D analysis using weight-bearing CT scans

BackgroundFlatfoot is a condition resulting from complex three-dimensional (3D) morphological changes. Most Previous studies have been constrained by using two-dimensional radiographs and non-weight-bearing conditions. The deformity in flatfoot is associated with the 3D morphology of the bone. These morphological changes affect the force line conduction of the hindfoot/midfoot/forefoot, leading to further morphological alterations. Given that a two-dimensional plane axis overlooks the 3D structural information, it is essential to measure the 3D model of the entire foot in conjunction with the definition under the standing position. This study aims to analyze the morphological changes in flatfoot using 3D measurements from weight-bearing CT (WBCT).MethodIn this retrospective comparative our CT database was searched between 4–2021 and 3–2022. Following inclusion criteria were used: Patients were required to exhibit clinical symptoms suggestive of flatfoot, including painful swelling of the medial plantar area or abnormal gait, corroborated by clinical examination and confirmatory radiological findings on CT or MRI. Healthy participants were required to be free of any foot diseases or conditions affecting lower limb movement. After applying the exclusion criteria (Flatfoot with other foot diseases), CT scans (mean age = 20.9375, SD = 16.1) confirmed eligible for further analysis. The distance, angle in sagittal/transverse/coronal planes, and volume of the two groups were compared on reconstructed 3D models using the t-test. Logistic regression was used to identify flatfoot risk factors, which were then analyzed using receiver operating characteristic curves and nomogram.ResultThe flatfoot group exhibited significantly lower values for calcaneofibular distance (p = 0.001), sagittal and transverse calcaneal inclination angle (p < 0.001), medial column height (p < 0.001), sagittal talonavicular coverage angle (p < 0.001), and sagittal (p < 0.001) and transverse (p = 0.015) Hibb angle. In contrast, the sagittal lateral talocalcaneal angle (p = 0.013), sagittal (p < 0.001) and transverse (p = 0.004) talocalcaneal angle, transverse talonavicular coverage angle (p < 0.001), coronal Hibb angle (p < 0.001), and sagittal (p < 0.001) and transverse (p = 0.001) Meary’s angle were significantly higher in the flatfoot group. The sagittal Hibb angle (B = − 0.379, OR = 0.684) and medial column height (B = − 0.990, OR = 0.372) were identified as significant risk factors for acquiring a flatfoot.ConclusionThe findings validate the 3D spatial position alterations in flatfoot. These include the abduction of the forefoot and prolapse of the first metatarsal proximal, the arch collapsed, subluxation of the talonavicular joint in the midfoot, adduction and valgus of the calcaneus, adduction and plantar ward movement of the talus in the hindfoot, along with the first metatarsal’s abduction and dorsiflexion in the forefoot.

Deep learning-based pseudo-CT synthesis from zero echo time MR sequences of the pelvis

ObjectivesTo generate pseudo-CT (pCT) images of the pelvis from zero echo time (ZTE) MR sequences and compare them to conventional CT.MethodsNinety-one patients were prospectively scanned with CT and MRI including ZTE sequences of the pelvis. Eleven ZTE image volumes were excluded due to implants and severe B1 field inhomogeneity. Out of the 80 data sets, 60 were used to train and update a deep learning (DL) model for pCT image synthesis from ZTE sequences while the remaining 20 cases were selected as an evaluation cohort. CT and pCT images were assessed qualitatively and quantitatively by two readers.ResultsMean pCT ratings of qualitative parameters were good to perfect (2–3 on a 4-point scale). Overall intermodality agreement between CT and pCT was good (ICC = 0.88 (95% CI: 0.85–0.90); p < 0.001) with excellent interreader agreements for pCT (ICC = 0.91 (95% CI: 0.88–0.93); p < 0.001). Most geometrical measurements did not show any significant difference between CT and pCT measurements (p > 0.05) with the exception of transverse pelvic diameter measurements and lateral center-edge angle measurements (p = 0.001 and p = 0.002, respectively). Image quality and tissue differentiation in CT and pCT were similar without significant differences between CT and pCT CNRs (all p > 0.05).ConclusionsUsing a DL-based algorithm, it is possible to synthesize pCT images of the pelvis from ZTE sequences. The pCT images showed high bone depiction quality and accurate geometrical measurements compared to conventional CT.Critical relevance statementpCT images generated from MR sequences allow for high accuracy in evaluating bone without the need for radiation exposure. Radiological applications are broad and include assessment of inflammatory and degenerative bone disease or preoperative planning studies.Key PointspCT, based on DL-reconstructed ZTE MR images, may be comparable with true CT images.Overall, the intermodality agreement between CT and pCT was good with excellent interreader agreements for pCT.Geometrical measurements and tissue differentiation were similar in CT and pCT images.Graphical

Anatomical study of the C6 pedicle and lateral mass in children aged 0–14 years based on CT imaging

ObjectiveThis study aims to investigate the anatomical structure of the C6 pedicle and lateral mass in children aged 0–14 years using CT imaging, providing detailed insights into their growth and development.MethodsWe conducted a comprehensive measurement of C6. Measurements included width, length, and height of the pedicles, as well as the length, width, and thickness of the lateral masses, and several angular metrics. Regression analysis was performed to understand the growth trends, and statistical analyses were carried out to identify differences between age groups, genders, and sides.ResultsIn children younger than four years, the pedicle width exceeds its height, influencing the diameter of the pedicle screws. By age two to three, the pedicle height and lateral mass thickness reaches 3.0 mm, allowing for the use of 3.0 mm diameter screws. The pedicle transverse angle remains stable. Most parameters showed no significant differences between the left and right sides. Size parameters exhibited significant larger in males than females at ages 0–1, 3–7, and 10–12 years. Regression analysis revealed that the growth trends of size parameters follow cubic or polynomial curves. Most angular metrics follow cubic fitting curves without a clear trend of change with age.ConclusionThis study provides a detailed analysis of the anatomical development of the C6 pedicle and lateral masses in children, offering valuable insights for pediatric cervical spine surgeries. The findings highlight the importance of considering age-specific anatomical variations when planning posterior surgical fixation, specifically at C6. It is necessary for us to perform thin-layer CT scans on children and carefully measure various indicators before surgery.

Low Concentrating Photovoltaic Geometry for Retrofitting Onto European Building Stock

Abstract The most appropriate low concentrating photovoltaic (LCPV) technology suitable for European buildings located in mid-high latitudes under both maritime and continental climatic conditions has been identified as the asymmetric compound parabolic concentrator (ACPC). To date, there is no published experimental data at different latitudes on the long-term performance of these systems at these latitudes nor how location would modify the optical characteristics of deployed systems. Previous theoretical research by the authors has demonstrated the superiority of the ACPC with this additional work experimentally confirming the robustness of the design. To investigate how seasonal and locational variations affect their measured technical performance two identical ACPC-LCPVs were installed, instrumented, and monitored at two different climatic locations (Uxbridge, UK, and Vevey, Switzerland) from May 2020 to September 2020. A valid comparative performance investigation characterizing two geometrically equivalent ACPC-based LCPV systems using real-life experimental data collected is presented in this paper. Locations at higher latitudes experience greater transverse angles more frequently compared to locations nearer the equator making ACPC geometries more appropriate than symmetrical concentrator configurations for building retrofit. This is shown in this paper over a latitudinal expanse of 31.35 deg for four separate locations; Tessalit (20.19 deg N, 1.00 deg E; Mali), Timimoun (28.03 deg N, 1.65 deg E; Algeria), Uxbridge (51.54 deg N, 0.48 deg E, UK), and Vevey (46.6 deg N, 6.84 deg E, Switzerland).

A novel technique for C1-C2 posterior screw insertion using patient-specific guides created by CT-based 3D printing.

C1-C2 fixation has been developed for the rigid fusion of atlantoaxial instability. C1 lateral mass screw (C1 LMS)-C2 pedicle screw fixation is used more frequently due to its rigid fixation and high bone fusion rate. However, C1 screw placement is relatively unsafe even with recently developed image-based navigation systems. Patient-specific screw guide templates (PSGT) were developed to improve the accuracy and safety of C1 screw placement. Herein, we investigated the outcomes of the C1-C2 posterior fixation technique using PSGT. This was a retrospective study of six patients who underwent posterior cervical spinal fusion using the PSGT between January 2022 and April 2023. Operative time, estimated blood loss, intraoperative radiation dose, surgical cost, and screw placement accuracy were evaluated and compared with those achieved with preoperative CT-based navigation (navigation group, n = 15). Screw accuracy was assessed using Neo's classification. PSGT showed good results, although the differences were not statistically significant (operation time: 104.3 ± 9.7 min vs 116.4 ± 20.8 min; estimated blood loss: 56.7 ± 72.4 mL vs 123.2 ± 162.3 mL; and radiation dose: 1.8 ± 1.2 mSv vs 2.6 ± 0.8 mSv, respectively). PSGT was particularly better in terms of the accuracy of C1 LMS (PSGT: 100%, navigation: 83.3%). The deviation at the entry point was minimal, and the difference between the sagittal and transversal angles from the preoperative plan was small. We investigated the clinical efficacy of using the PSGT for C1-C2 posterior fixation. PSGT improved the accuracy of C1 LMS insertion.

Unraveling the gait dynamics - A comparative study of iASSIST and conventional total knee replacement techniques in osteoarthritic elderly patients

BackgroundOsteoarthritis (OA) stands as the most prevalent disability among the elderly population. Assessing functional outcomes after Total Knee Replacement (TKR) typically involves Gait analysis along with other evaluation methods. The objective of this study was to compare Gait results, including temporospatial parameters, joint angles, gait profile score (GPS), and movement analysis profiles (MAP), between conventional and iASSIST TKR techniques. MethodThe study involved 21 participants (mean age 68.4 ± 4.2 years), with 16 females and 5 males. Among them, 11 patients had traditional surgery (15 TKR), and 10 patients had iASSIST surgery (13 TKR), totaling 28 knees (7 bilateral). The pre-operative Gait analysis was conducted one day before the surgical procedure, whereas the postoperative Gait analysis was performed, on average, 210 ± 20 days after surgery. Gait analysis was conducted using the Qualisys Motion capture system, operating at a rate of 120 Hz. The data were thoroughly analyzed using Visual 3D C-Motion Software. ResultsAn analysis of gait biomechanics metrics, encompassing temporospatial parameters, joint angles, GPS, and MAP, was undertaken. Significant differences were observed in sagittal plane joint angles of the pelvis and hip, transverse plane joint angles of the knee, cadence, and MAP of foot internal/external rotation. However, there were no statistically significant differences between the two TKR techniques in the remaining temporospatial variables, joint angles, GPS, or MAP. ConclusionThis study revealed a significant difference between iASSIST-guided TKR and conventional TKR, demonstrating that the iASSIST procedure led to improvements in walking biomechanics. Findings hold potential utility for orthopedic surgeons in their decision-making processes, ultimately contributing to the improvement of functional outcomes following TKR.

Lumbar Pedicle Dimensions Using CT Scan in Adults of South-Eastern Nigeria as Related to Transpedicular Fixation.

Transpedicular fixation depends on accuracy of the entry points, angle of insertion and pedicular isthmus width for adequate screw insertion. Preoperative measurements of pedicle dimensions reduce the chances of failure during insertion. These pedicle dimensions (transverse diameter, longitudinal diameter, and maximum length of purchase [MLP]) vary with sex and race. Such data, from a large-scale study, are not available for our population. The study aims to evaluate the dimensions of pedicle that are relevant for pedicle screw fixation in Southeast Nigerian population. A prospective multi-slice CT based clinical anatomy study done at Memfys Hospital for Neurosurgery, Enugu. This study is on the lumbar pedicle dimensions that are related to transpedicular fixation (transverse and longitudinal diameters of the pedicle, MLP, pedicle transverse and longitudinal angles of inclination). Sample size (273) was calculated with the confidence interval formula based on the number of patients that present for images. Consent and ethical approval were obtained. The mean values are as follow: LD1 8.22 mm, LD2 7.73 mm, LD3 7.40 mm, LD4 7.16 mm, LD5 6.87 mm TD1 5.05 mm, TD2 5.31 mm, TD3 6.72 mm, TD4 8.27 mm, TD5 11.31 mm, MLP1 46.60 mm, MLP2 47.97 mm, MLP3 47.14 mm, MLP4 45.54 mm, MLP5 43.47 mm TA1 17.8°, TA2 19.34°, TA3 20.80°, TA4 22.00°, TA5 25.70° LA1 19.42°, LA2 18.61°, LA3 18.00°, LA4 17.09°, LA5 16.40°. Unlike transverse diameter, transverse angle, longitudinal dimension, longitudinal angle (LA), MLP there was significant correlation between age and mean LA. The mean values also correlated significantly with the gender. The mean values varied with the different vertebral levels and was good correlations between some of the parameters with age and gender.

Biomechanical effects of posterior lumbar interbody fusion with vertical placement of pedicle screws compared to traditional placement.

The pedicle screw technique is widely employed for vertebral body fixation in the treatment of spinal disorders. However, traditional screw placement methods require the dissection of paraspinal muscles and the insertion of pedicle screws at specific transverse section angles (TSA). Larger TSA angles require more force to pull the muscle tissue, which can increase the risk of surgical trauma and ischemic injury to the lumbar muscles. To study the feasibility of zero-degree TSA vertical pedicle screw technique in the lumbosacral segment. Finite element models of vertebral bodies and pedicle screw-rod systems were established for the L4-S1 spinal segments. A standard axial load of 500 N and a rotational torque of 10 N/m were applied. Simulated screw pull-out experiment was conducted to observe pedicle screw resistance to pull-out, maximum stress, load-displacement ratio, maximum stress in vertebral bodies, load-displacement ratio in vertebral bodies, and the stress distribution in pedicle screws and vertebral bodies. Differences between the 0-degree and 17-degree TSA were compared. At 0-degree TSA, the screw pull-out force decreased by 11.35% compared to that at 17-degree TSA (P < 0.05). At 0-degree and 17-degree TSA, the stress range in the screw-rod system was 335.1-657.5 MPa and 242.8-648.5 MPa, separately, which were below the fracture threshold for the screw-rod system (924 MPa). At 0-degree and 17-degree TSA, the stress range in the vertebral bodies was 68.45-78.91 MPa and 39.08-72.73 MPa, separately, which were below the typical bone yield stress range for vertebral bodies (110-125 MPa). At 0-degree TSA, the load-displacement ratio for the vertebral bodies and pedicle screws was slightly lower compared to that at 17-degree TSA, indicating slightly lower stability (P < 0.05). The safety and stability of 0-degree TSA are slightly lower, but the risks of screw-rod system fracture, vertebral body fracture, and rupture are within acceptable limits.

Movement Quality Assessment of Army Reserve Officers' Training Corps Cadets: A Report of Validity and Normative Data.

Movement quality screening in early-career military populations, like Army Reserve Officers' Training Corps (AROTC) cadets, could decrease the negative impact of musculoskeletal injury observed within the military. Movement quality screening techniques should be valid before being pursued in the field. Normative data describing movement quality of AROTC cadets are also needed. Therefore, the aims of this study were to determine criterion validity of several movement quality assessments and report normative jump-landing kinematics of AROTC cadets. This cross-sectional research was approved by the Institutional Review Board. As part of a larger study, 20 AROTC cadets (21.3 ± 3.4 years; 1.7 ± 0.1 m; 73.8 ± 14.8 kg) had 3-dimensional (3D) and 2-dimensional (2D) kinematic data collected simultaneously while performing a jump-landing task. Variables of interest were 3D hip and knee sagittal, frontal, and transverse joint angles at maximum knee flexion. An experienced rater calculated sagittal and frontal 2D joint angles at maximum knee flexion. Averages of 2D and 3D angles were calculated to describe normative data and for further data analysis. Bivariate correlations between 3D and 2D variables were used to determine criterion validity. Moderate correlations were found between 2D and 3D hip frontal plane angles (P = .05, r =-0.33), 2D and 3D knee sagittal plane angles (P = .04, r = 0.35), and 2D and 3D knee frontal plane angles (P = .03, r = -0.36). Normative values of knee and hip kinematics demonstrated averages of 17.58° of knee adduction, 16.48° of knee external rotation, 11.57° of hip abduction, 10.76° of hip internal rotation, and 103.47° of knee flexion during landings. However, ranges demonstrated that landing patterns vary within AROTC cadets. The normative values of 3D jump-landing kinematic data indicate that movement quality varies greatly within AROTC cadets, and some cadets display potentially injurious movements. Therefore, screening movement quality could be beneficial to determine musculoskeletal injury risk in AROTC cadets. Based on the correlations discovered in this study, we recommend the 2D techniques used in this study be researched further as they may serve as alternatives to expensive, timely 3D techniques that could be better utilized in military environments.

Optimal curvature radius of cylindrical mirrors in linear Fresnel reflectors

The optical performance of linear Fresnel reflectors (LFRs) is heavily influenced by the curvature of their cylindrical mirrors. An innovative approach to calculating the optimal curvature radius of cylindrical mirrors in LFRs is introduced. Firstly, an optimization calculation method is proposed to determine the curvature radius of the cylindrical mirror. Then, a universal computational model for the curvature radius of cylindrical mirrors is established. Finally, a detailed analysis is conducted on the impact of optimizing the cylindrical mirrors on the optical performance of LFRs. Optical simulation results indicate that optimizing the curvature radius of the mirror significantly reduces the lateral drift of reflected rays. Increasing slope error, tracking error, and curvature radius error of the cylindrical mirrors result in decreased optical efficiency gain in the optimized LFR while improving uniformity. Furthermore, a larger transversal incidence angle yields a more pronounced improvement in the optimized gain, demonstrating a substantial enhancement in optical efficiency without compromising uniformity in LFRs. The average optical efficiency gain of the LFR is measured at 7.09 %, with an average uniformity loss of 2.10 % under all the studied conditions.