Search Results (6)

Rectangular shield tunnels demonstrate significant advantages in underground space utilization due to their optimal cross-section efficiency and enhanced spatial functionality. Furthermore, their shallow overburden construction capability minimizes environmental impact and preserves subsurface resources. However, compared with circular shield tunnels, rectangular configurations exhibit greater susceptibility to longitudinal differential torsional deformation under asymmetric external loading. This deformation mechanism may induce excessive stresses in segments and connecting bolts, potentially causing joint offsets at tunnel rings that compromise structural integrity. This paper proposes a computational method for determining the longitudinal equivalent torsional stiffness of rectangular shield tunnels under combined compression–bending–torsion loading based on an equivalent continuum model. The proposed novel theoretical solutions were systematically validated against numerical simulations through comparative analysis. Parametric studies revealed that the effective ratio of longitudinal torsional stiffness increases proportionally with segment width-to-height ratio and bolt quantity while exhibiting inverse correlations with segment thickness and bolt equivalent shear length. The effective ratio of longitudinal torsional stiffness is directly correlated with compression–torsion ratios and bending–torsion ratios, with different load combinations significantly influencing torsional performance. Consequently, design optimizations incorporating increased bolt pre-tension forces or pre-stressed segment structures are proposed to improve torsional performance in rectangular shield tunneling systems. Full article

Background: Temporomandibular joint (TMJ) disorders are a significant cause of orofacial pain. Artificial intelligence (AI) has been successfully applied to other imaging modalities but remains underexplored in ultrasonographic evaluations of TMJ. Objective: This study aimed to develop and validate an AI-driven method for the automatic and reproducible measurement of TMJ space width from ultrasonographic images. Methods: A total of 142 TMJ ultrasonographic images were segmented into three anatomical components: the mandibular condyle, joint space, and glenoid fossa. State-of-the-art architectures were tested, and the best-performing 2D Residual U-Net was trained and validated against expert annotations. The algorithm for joint space width measurement based on TMJ segmentation was proposed, calculating the vertical distance between the superior-most point of the mandibular condyle and its corresponding point on the glenoid fossa. Results: The segmentation model achieved high performance for the mandibular condyle (Dice: 0.91 ± 0.08) and joint space (Dice: 0.86 ± 0.09), with notably lower performance for the glenoid fossa (Dice: 0.60 ± 0.24), highlighting variability due to its complex geometry. The TMJ space width measurement algorithm demonstrated minimal bias, with a mean difference of 0.08 mm and a mean absolute error of 0.18 mm compared to reference measurements. Conclusions: The model exhibited potential as a reliable tool for clinical use, demonstrating accuracy in TMJ ultrasonographic analysis. This study underscores the ability of AI-driven segmentation and measurement algorithms to bridge existing gaps in ultrasonographic imaging and lays the foundation for broader clinical applications. Full article

We previously reported that elbow magnetic resonance imaging (MRI) with 7 kg traction increases the joint space width of the radiocapitellar joint and improves articular cartilage visibility without arthrography. However, the optimal traction weight remains unclear. We assessed the effects of different traction weights on elbow MRI in 30 healthy volunteers. Elbow MRI was performed without traction and with 3, 5, and 7 kg axial tractions. The joint space width, humeral articular cartilage outline visibility, and intraprocedural pain/discomfort were evaluated. The joint and cartilage parameters were measured at the radiocapitellar joint and the lateral and medial thirds of the ulnohumeral joint. At the radiocapitellar joint, the joint space width increased significantly with traction. The cartilage outline visibility significantly increased with traction, with no significant differences among the traction weights. No significant result was observed at the lateral and medial thirds of the ulnohumeral joint. Pain and discomfort significantly increased as we used heavier traction weights. Elbow MRI with 3 kg traction showed sufficient effects similar to those observed with 7 kg traction with minimal pain and discomfort. There was no difference in the effect of traction between male and female participants. This procedure may enable enhanced visualization of intra-articular elbow injuries. Full article

Minimal joint space width (mJSW) is a radiographic measurement used in the diagnosis of hip osteoarthritis. A large variance when measuring mJSW highlights the need for a supporting diagnostic tool. This study aimed to estimate the reliability of a deep learning algorithm designed to measure the mJSW in pelvic radiographs and to estimate agreement between the algorithm and orthopedic surgeons, radiologists, and a reporting radiographer. The algorithm was highly consistent when measuring mJSW with a mean difference at 0.00. Human readers, however, were subject to variance with a repeatability coefficient of up to 1.31. Statistically, although not clinically significant, differences were found between the algorithm’s and all readers’ measurements with mean measured differences ranging from −0.78 to −0.36 mm. In conclusion, the algorithm was highly reliable, and the mean measured difference between the human readers combined and the algorithm was low, i.e., −0.5 mm bilaterally. Given the consistency of the algorithm, it may be a useful tool for monitoring hip osteoarthritis. Full article

The eccentric RHS (rectangular hollow sections) joint offers improved mechanical properties and better space utilization. Its use in frame structures has gained significant attention. Currently, the initial rotational stiffness of RHS joints, the simplified finite element analysis method of eccentric RHS joints, and the influence of the spatial effect of RHS joints are still unknown. The purpose of this research is to establish a calculation formula for the initial rotational stiffness of eccentric RHS joints, study the influence of the spatial effect under complex stress conditions, and propose a mathematical model that can be used to simplify the analysis of eccentric RHS joints. The research findings indicate that the web plate’s deformation stiffness primarily influences the joints’ initial rotational stiffness. This increases with a higher beam-to-column depth-to-width ratio, beam-to-column thickness ratio, and column width-to-thickness ratio. The form of the moment distribution in the joint changes, and begins to have a significant effect on the rotational stiffness when the beam-to-column flange width ratio reaches and exceeds 0.7. The stiffeners have a direct additive effect on the joint stiffness. The influence of adjacent beams on the joint is minimal, and the spatial effect of the joint can be disregarded. Furthermore, the finite element analysis confirmed the accuracy of the power function model in accurately simulating the static load behavior of the joint, particularly the bending moment–angle relationship. Full article

Doxycycline is a drug that has been proposed to modify osteoarthritis (OA) progression, in addition to its role as an antibiotic. However, available evidence thus far comprises sporadic reports, with no consensus on its benefits. Hence, this review attempts to analyze the evidence available thus far on the role of doxycycline as a disease-modifying osteoarthritis drug (DMOAD) in knee osteoarthritis. The earliest evidence of doxycycline in OA appeared in 1991 when doxycycline was found to inhibit the type XI collagenolytic activity of extracts from the human osteoarthritic cartilage, and gelatinase and tetracycline were found to inhibit this metalloproteinase activity in articular cartilage in vivo, which could modify cartilage breakdown in osteoarthritis. Apart from the inhibition of cartilage damage by metalloproteinases (MMPs) and other cartilage-related mechanisms, doxycycline also affects the bone and interferes with many enzyme systems. The most significant finding after reviewing various studies was that doxycycline has a definitive role in structural changes in osteoarthritis progression and radiological joint space width, but its role in the improvement of clinical outcomes as a DMOAD has not been established. However, there is much of a gap and lack of evidence in this regard. Doxycycline, as an MMP inhibitor, has theoretical advantages for clinical outcomes, but the present studies reveal only beneficial structural changes in osteoarthritis and very minimal or nonexistent advantages in clinical outcomes. Current evidence does not favor the regular use of doxycycline for the treatment of osteoarthritis as an individual treatment option or in combination with others. However, multicenter large cohort studies are warranted to determine the long-term benefits of doxycycline. Full article