Joint Surface Research Articles

Research on circumferential joint shear damage characteristics of segments with positioning tenon through distributed fiber optic-based sensing technique

Positioning tenons have been used in more and more subway projects to improve segment assembly performance and to limit the occurrence of common problems between segments. The joints are the weak parts of the segment connection and are often damaged during construction. However, there are limited studies on the joints of segments with positioning tenons, and their damage characteristics have yet to be investigated. In this study, circumferential joint shear damage in segments with positioning tenons is studied and the evolution of the distributed damage is monitored by distributed fiber optics. First of all, the shear performance of segments with positioning tenons is investigated under different axial forces. Particularly, the damage distribution and development of segments subjected to the extrusion of the positioning tenons are analyzed through the strain signals and the macroscopic cracks during the shearing process. Furthermore, the changes in the strain signals of the distributed fiber before shear failure are analyzed. Based on the above study, the failure patterns of the inner surfaces and circumferential joint surfaces of segments with grooves are revealed. The interaction between the positioning tenons and the segments is analyzed, and the damage characteristics of the tenons are obtained. Finally, the main crack shear coefficient is proposed to evaluate the residual shear performance of segments when the macroscopic main crack occurs on the inner surface. This study aims to reveal the interaction between positioning tenons and segments and to promote the application of positioning tenons in subways. Further, it lays the foundation for optimizing the flexible joints of segments in subways and contributes to the safe construction of subway tunnels.

Comparison of radiography and computed tomography for identification of third metacarpal structural change and associated assessment of condylar stress fracture risk in Thoroughbred racehorses.

Catastrophic injury has a low incidence but leads to the death of many Thoroughbred racehorses. To determine sensitivity, specificity, and reliability for third metacarpal condylar stress fracture risk assessment from digital radiographs (DR) and standing computed tomography (sCT). Controlled ex vivo experiment. A blinded set of metacarpophalangeal joint DR and sCT images were prepared from 31 Thoroughbreds. Four observers evaluated the condyles and parasagittal grooves (PSG) of the third metacarpal bone for the extent of dense bone and lucency/fissure and assigned a risk assessment grade for condylar stress fracture based on imaging features. Sensitivity and specificity for detection of subchondral structural changes in the condyles and PSG, and for risk assessment for condylar stress fracture were determined by comparison with a reference assessment based on sCT and joint surface examination. Agreement between observers and the reference assessment and reliability between observers were determined. Intra-observer repeatability was also assessed. Sensitivity for detection of structural change was lower than specificity for both imaging methods and all observers. For agreement with the reference assessment of structural change, correlation coefficients were generally below 0.5 for DR and 0.49-0.82 for sCT. For horses categorised as normal risk on reference assessment, observer assessment often agreed with the reference. Sensitivity for risk assessment was lower than specificity for all observers. For horses with a reference assessment of high risk of injury, observers generally underestimated risk. Diagnostic sensitivity of risk assessment was improved with sCT imaging, particularly for horses categorised as having elevated risk of injury from the reference assessment. Assessment repeatability and reliability was better with sCT than DR. The ex vivo study design influenced DR image sets. Risk assessment through screening with diagnostic imaging is a promising approach to improve injury prevention in racing Thoroughbreds. Knowledge of sensitivity and specificity of fetlock lesion detection provides the critical guidance needed to improve racehorse screening programs. We found improved detection of MC3 subchondral structural change and risk assessment for condylar stress fracture with sCT ex vivo.

Experiment on the Tensile Strength of Concrete Joint Surface at Early Ages

Experiment on the Tensile Strength of Concrete Joint Surface at Early Ages

Drive-By Identification of Joint Bridge Damage and Surface Roughness Based on Sensitivity Analysis of Residual Contact Point Deflections

Drive-by inspection of bridge damage using a passing vehicle’s dynamic response has great potential in bridge damage identification. Among the current drive-by methodologies, the methods based on bridge modeling have been proposed for the quantitative identification of bridge damage and bridge surface roughness. However, the coupling of bridge damage and unknown surface roughness increases the difficulty of the identification problem and most previous studies conduct the identification task of bridge damage or bridge surface roughness separately. In this paper, a novel method is proposed for the identification of joint bridge damage and bridge surface roughness based on the residual bridge deflections from the front and rear wheels contact points of an instrumented passing vehicle. The vehicle–bridge interaction is analyzed using a half-car model of a four degrees of freedom (4-DOF) with front and rear vehicle wheels. First, the vehicle–bridge unknown forces and displacement of the vehicle axles are identified by the generalized Kalman filter under unknown input (GKF-UI) proposed by the authors. The sensors can be installed conveniently on the vehicle body due to GKF-UI. Then, the residual bridge deflections from the front and rear vehicle wheels contact points are utilized to eliminate the effect of road surface roughness. Afterward, bridge structural damage is identified based on the sensitivity analysis of residual bridge deflections from the front and rear contact points with [Formula: see text]1-norm regularization. Finally, bridge road surface roughness is estimated based on the identified unknown forces and updated bridge model with damage. The results of numerical identification examples demonstrate the effectiveness of the proposed method for the identification of joint bridge damage and surface roughness.

Biomechanical Effects of Different Prosthesis Types and Fixation Ranges in Multisegmental Total En Bloc Spondylectomy: A Finite Element Study.

Multi-segmental total en bloc spondylectomy (TES) gradually became more commonly used by clinicians. However, the choice of surgical strategy is unclear. This study aims to investigate the biomechanical performance of different prosthesis types and fixation ranges in multisegmental TES. In this study, a validated finite element model of T12-L2 post-spondylectomy operations were carried out. The prostheses of these models used either 3D-printed artificial vertebrae or titanium mesh cages. The fixed range was two or three segment levels. Range of motion, stress distribution of the endplate and internal fixation system, intervertebral disc pressure, and facet joint surface force of four postoperative models and intact model in flexion and extension, as well as lateral bending and rotation were analyzed and compared. The type of prosthesis used in the anterior column reconstruction mainly affected the stress of the adjacent endplate and the prosthesis itself. The posterior fixation range had a greater influence on the overall range of motion (ROM), the ROM of the adjacent segment, the stress of the screw-rod system, and adjacent facet joint surface force. For the model of the same prosthesis, the increase of fixed length resulted in an obvious reduction of ROM. The maximal decrease was 70.23% during extension, and the minimal decrease was 30.19% during rotation. In three-segment TES, the surgical strategy of using 3D-printed artificial prosthesis for anterior column support and pedicle screws for posterior fixation at both two upper and lower levels respectively can reduce the stress on internal fixation system, endplates, and adjacent intervertebral discs, resulting in a reduced risk of internal fixation failure, and ASD development.

Zirconia and Crofer Joint Made by Reactive Air Brazing Using the Silver Base Paste and Cu-Ti Coating Layer.

This study proposes a method to enhance the airtightness of the joint between the ZrO2 and Crofer alloy using coating technology. With the aid of vacuum sputtering technology, a titanium-copper alloy layer with a thickness between 1.5 μm and 6 μm was first deposited on the surface of ZrO2 and Crofer, respectively. The chemical composition of the deposited reaction layer was 70.2 Cu and 29.8 Ti in at%. Then, using silver as the base material in the reactive air brazing (RAB) process, we explore the use of this material design to improve the microstructure and reaction mechanism of the joint surface between ceramics and metal, compare the effects of different pretreatment thicknesses on the microstructure, and evaluate its effectiveness through air tightness tests. The results show that a coating of Cu-Ti alloy on the ZrO2 substrate can significantly improve bonding between the Ag filler and ZrO2. The Cu-Ti metallization layer on the ZrO2 substrate is beneficial to the RAB. After the brazing process, the coated Cu-Ti layers form suitable reaction interfaces between the filler, the metal, the filler, and the ceramic. In terms of coating layer thickness, the optimized 3 μm coated Cu-Ti alloy layer is achieved from the experiment. Melting and dissolving the Cu-Ti coated layer into the ZrO2 substrate results in a defect-free interface between the Ag-rich braze and the ZrO2. The air tightness test result shows no leakage under 2 psig at room temperature for 28 h. The pressure condition can still be maintained even under high-temperature conditions of 600 °C for 24 h.

Morphological and morphometric analysis of tarsal bones according to sex.

Our aim in the study is to measure the area and volume of the tarsal bones and examine the typing of the talus and calcaneus joint surfaces according to sex. In our study, the area and volume measurements of 630 tarsal bones and the morphology of the talus/calcaneus were analyzed by transferring thin-section Computed Tomography (CT) images to the 3D Slicer program. The volume and area sizes of the foot bones are calcaneus, talus, cuboid, navicular, medial cuneiform, lateral cuneiform, and intermediate cuneiform, respectively. All area and volume values of males were statistically higher than females (p < 0.05). The right side calcaneus area, intermediate cuneiform area, and lateral cuneiform area values were statistically higher than the left side (p < 0.045, p < 0.044, p < 0.030, respectively). There was no statistical relationship between age and area/volume values (p > 0.05). Three different types were seen in the calcaneus and seven in the talus. The most common type in the calcaneus was B1 (40%), and the least common type was A (27.8%). Regardless of the subgroups, the most common type in the talus was type B (37.8%), while the least common type was E2 (1.1%). Although morphometric measurements of tarsal bones differed according to sex, they did not differ according to age. The frequency of occurrence of the types of articular surfaces of the talus and calcaneus varies according to populations. We think that the morphometry and morphology of tarsal bones will contribute to invasive procedures regarding tarsal bones and surrounding structures, and that three-dimensional bone modeling can be used to create educational materials.

Articular Surface Damage Following Headless Intramedullary Nail Fixation of Proximal Phalanx Fractures

Offering the benefits of rigid fixation while minimizing soft tissue dissection, intramedullary implants have become a popular choice among hand surgeons. Their placement often requires traversing or passing in proximity to joint surfaces. This study aimed to assess the damage to the articular cartilage of the base of the proximal phalanx resulting from antegrade placement of threaded headless intramedullary nails. A cadaveric study comparing two techniques for antegrade placement of threaded headless intramedullary nails was conducted in 56 digits. The first entailed a single 2.1 mm intramedullary nail placed via the dorsal base of the proximal phalanx, whereas the second used two 1.8 mm intramedullary nails inserted via the collateral recesses of the phalangeal base. All specimens were analyzed for articular surface damage with the cartilage defect measured as a percentage of total joint surface area. Damage to the extensor tendons was also assessed in a subset of specimens. No significant difference in the percentage of articular surface damage was observed, with an average 3.21% ± 2.34% defect in the single 2.1 mm nail group and a 2.71% ± 3.42% mean defect in the two 1.8 mm nails group. There was no articular surface injury in 18% of digits in each group. Damage to extensor tendons was seen in three (9.4%) specimens and in all cases involved either the extensor indicis proprius or extensor digiti minimi. Hardware insertion using either the dorsal base of the proximal phalanx or the collateral recesses of the phalangeal base both demonstrated minimal articular cartilage damage and infrequent injury to the extensor tendons. With proper technique for antegrade insertion into the proximal phalanx, the cartilage defect observed often encompasses only a small percentage of the overall joint surface area.

Computational biomechanical study on hybrid implant materials for the femoral component of total knee replacements

Multifunctional materials have been described to meet the diverse requirements of implant materials for femoral components of uncemented total knee replacements. These materials aim to combine the high wear and corrosion resistance of oxide ceramics at the joint surfaces with the osteogenic potential of titanium alloys at the bone-implant interface. Our objective was to evaluate the biomechanical performance of hybrid material-based femoral components regarding mechanical stress within the implant during cementless implantation and stress shielding (evaluated by strain energy density) of the periprosthetic bone during two-legged squat motion using finite element modeling. The hybrid materials consisted of alumina-toughened zirconia (ATZ) ceramic joined with additively manufactured Ti–6Al–4V or Ti–35Nb–6Ta alloys. The titanium component was modeled with or without an open porous surface structure. Monolithic femoral components of ATZ ceramic or Co–28Cr–6Mo alloy were used as reference. The elasticity of the open porous surface structure was determined within experimental compression tests and was significantly higher for Ti–35Nb–6Ta compared to Ti–6Al–4V (5.2 ± 0.2 GPa vs. 8.8 ± 0.8 GPa, p < 0.001). During implantation, the maximum stress within the ATZ femoral component decreased from 1568.9 MPa (monolithic ATZ) to 367.6 MPa (Ti–6Al–4V/ATZ), 560.9 MPa (Ti–6Al–4V/ATZ with an open porous surface), 474.9 MPa (Ti–35Nb–6Ta/ATZ), and 648.4 MPa (Ti–35Nb–6Ta/ATZ with an open porous surface). The strain energy density increased at higher flexion angles for all models during the squat movement. At ∼90° knee flexion, the strain energy density in the anterior region of the distal femur increased by 25.7 % (Ti–6Al–4V/ATZ), 70.3 % (Ti–6Al–4V/ATZ with an open porous surface), 43.7 % (Ti–35Nb–6Ta/ATZ), and 82.5% (Ti–35Nb–6Ta/ATZ with an open porous surface) compared to monolithic ATZ. Thus, the hybrid material-based femoral component decreases the intraoperative fracture risk of the ATZ part and considerably reduces the risk of stress shielding of the periprosthetic bone.

Research on the influence of core plate joint surface type on the vibration performance of acoustic black hole sandwich panels

Research on the influence of core plate joint surface type on the vibration performance of acoustic black hole sandwich panels

Cone-beam computed tomography imaging and three-dimensional analysis of midfoot joints during non-weightbearing and weightbearing in 11 healthy feet.

Studies report that Lisfranc injury is more common than thought. Several imaging methods for assessing the stability of Lisfranc injury have been described but many are impossible to standardize and not accurate enough. To present a three-dimensional (3D) method for analyzing the changes in the joint space width of the midfoot joint and the joints of the medial part of the Lisfranc complex in healthy individuals. Non-weightbearing and weightbearing cone-beam computed tomography (CBCT) images of 11 healthy feet were acquired and analyzed with 3D software. The mean range of joint space width changes of each joint was computed from the changes in individual image pairs. 3D analysis software was used to analyze the medial part of the Lisfranc complex. In this sample of healthy feet, the changes in the joint spaces in the medial part of Lisfranc complex, calculated with 3D analysis software, was less than 0.6 mm. The distance between bones increased or decreased, depending on which part of the joint surface the measurements were taken. In this study, we present a 3D analysis method to evaluate midfoot joint space width changes. Our analysis revealed that in healthy feet there are only minimal changes in the joint space width between weightbearing and non-weightbearing indicating minimal movement of the midtarsal joints. The 3D analysis of weightbearing CBCT data provides a promising tool for analyzing the small midfoot joints in a variety of conditions.

Quantification of First Metatarsal Joint Surface Interactions in Hallux Rigidus Using Distance and Coverage Mapping: A Case-Control Study.

Weightbearing cone-beam computed tomography (WBCT) has proven useful for analysis of structural changes of the foot and ankle when compared to conventional radiographs. WBCT allows for extraction of distance and coverage mapping metrics, which may provide novel insight into hallux rigidus (HR). This study retrospectively assessed HR joint space using distance and coverage mapping in a case-control study. WBCT images of the foot and ankle for 20 symptomatic HR and 20 control patients were obtained. Three-dimensional models were created and analyzed using a custom semiautomatic measurement algorithm. Distance and coverage mapping metrics for the first metatarsophalangeal and metatarsosesamoid joints were extracted from the models and compared between cohorts. Relationships between these metrics and visual analog scale (VAS) scores, a patient-reported outcome of pain, were assessed in HR patients. Overall first metatarsophalangeal joint space narrowing was noted in HR patients when compared to controls by an average of 11.8% (P = .02). However, no significant changes in the overall coverage of the joint were noted. Decreased joint space width and increased surface-to-surface coverage were only and particularly observed at the plantar medial quadrant of the first metatarsal head in HR patients relative to controls. VAS score was significantly but weakly correlated with dorsolateral quadrant coverage (R2 = 0.26, P = .03). Distance and coverage mapping serve as a complementary option to current techniques of quantifying HR changes. These metrics can expand the scope of future work investigating joint articulation changes in HR.

Rock Mass Classification Systems: A Useful Rock Mechanics Tool, Often Misused

AbstractRock mass classification systems (RMCS) were developed in the seventies of the last century. They were born in response to the need to establish indicative design criteria for tunnel support. But they also focused on rating the quality of the rock, putting numbers in geology that allowed the rock mass to be classified and its parameters computed. RMCS attempted to consider the most relevant geomechanical aspects affecting the rock mass, including parameters related to rock structure and joint surface conditions. However, to be used as design approaches, they covered parameters not related to the rock mass itself (excavation orientation, stress state…). This multiple focus, together with other intrinsic limitations, has introduced some confusion in its application. A discussion is presented on the application of RMCS to solve rock engineering problems based on the author’s experience, addressing the geological background and their applications. The author reports on some small-scale rock engineering studies including the results of basic RMCS, presenting the potential problems encountered, if any, and the usefulness of the approach in relation to the objectives of the study. While a “design as you go” approach, based on RMCS of the tunnel face combined with observations, measurements and expertise, has often been successful, its direct application for design purposes without further considerations tends to produce problems. Very useful and almost necessary for comparative purposes, these simple approaches may, however, not always produce the right answers to design questions or may lead to wrong decisions if used without additional thoughtful considerations.

Case studies of the load-bearing performance of shield tunnel segment with misaligned defects

The segment misalignment is a common defect in the segment installation of a shield tunnel construction, due to the complexity and uncertainty of its construction conditions. This raises a concerning about the safety of the segment lining for the shield tunnel. In this paper, the integrated numerical models with surrounding rock, peastone grouting and segment lining were built using three-dimensional finite element method, by introducing two kinds of misaligned defects of segments. One was the misalignment that elongated the horizontal axis of the transversal ring section of segment lining, another was the misalignment between adjacent rings of segments. To eliminate the impact of boundary on numerical results, seven rings of segments are built for the three-dimensional finite element models, and the middle ring is dealt with for the results analysis under V-class surrounding rock, including the circumferential stress of outer and inner layers of the segment, the contact stress on joint surface between segments, and the stress of locating pins between adjacent rings. Results indicate that the two kinds of misaligned defects create pronounced impact on tensile stress of segment at the bottom and the crown segments, respectively, which produces a greater tensile stress to increase cracking risk even abrupt fracture of segment. However, the misaligned defects have a slight impact on the contact stress and the locating pins stress. Therefore, attention should be paid to the cracking of bottom or crown segments in the segment lining of shield tunnel.

Research on the Brazilian splitting characteristics and failure mechanism of jointed composite disks

The stress state of composite rock joints has a significant impact on the overall stability of the rock mass. Studying the composite mechanism disk specimens with different matrix strengths and inclination angles under Brazilian splitting state is of great significance for improving the safety of surrounding rock. This research conducted Brazilian tests on different types of jointed composite disk specimens at different inclination angles and explored the effects of inclination angle and material strength on the mechanical properties and deformation characteristics of specimens. Clarified the failure mechanism of joint specimen. The experimental results indicate that the disk specimens under different inclination angles exhibit three typical failure modes. As the inclination angle increases, failure mode changes from Disk matrix failure (DM failure) to Disk matrix and structural failure (DMS failure), and ultimately to Disk structural failure (DS failure). Failure load, input energy, and strain energy of the specimen continue to decrease as the inclination angle increases and the matrix strength decreases. The decrease in matrix material significantly weakens the strength of the specimen, but this effect continues to decrease with the increase of inclination angle. DIC results show that as the inclination angle increases, the position of cracks exists from the loading end to the joint surface. Through theoretical analysis, it is found that as the inclination angle increases, the stress state at the center of the specimens changes from compression-shear state to shear state, and finally to tension state, corresponding to three failure modes: DM failure, DMS failure, and DS failure, respectively.

Experimental study on shear mechanical characteristics and its size effect of concrete joints based on BP neural network method

In order to study the shear mechanical characteristics and its size effect on concrete joints, this paper uses the RDS-200 shear test system developed by GCTS company to carry out the indoor direct shear tests on concrete joint specimens with five kinds of JRC and five grades of joint surface size under five normal stress conditions. The results show that the pre-peak shear stiffness of concrete joints is not significantly affected by JRC and normal stress, but is significantly affected by the joint surface size. The pre-peak shear stiffness decreases with the increase of joint surface size, when the joint surface size increases from 35 mm to 95 mm, the pre-peak shear stiffness of specimens with JRC being 0 ∼ 2, 4 ∼ 6, 8 ∼ 10, 12 ∼ 14 and 16 ∼ 18 decreased by 66.96 %, 63.87 %, 71.67 %, 64.57 % and 66.32 %, respectively, with an average of 66.68 %. Moreover, with the increase of joint surface size, the decrease rate of pre-peak shear stiffness decreases gradually, which is basically exponential, that is because the pre-peak shear stiffness has negative size effect. In addition, the peak shear strength of concrete joints increases with the increase of normal stress and JRC, and the relationship between peak shear strength and normal stress conforms to the Mohr-Coulomb criterion. Furthermore, there is no obvious size effect on the peak shear strength of concrete joints in the range of 35–95 mm. An intelligent prediction method for predicting the peak shear strength and pre-peak shear stiffness of concrete joints considering JRC, joint surface size and normal stress was established. The prediction results show that the BP Neural Network optimized by genetic algorithm can effectively predict the peak shear strength and pre-peak shear stiffness of concrete joints, the average error of peak shear strength is about 4.91 %, and the average error of pre-peak shear stiffness is 9.37 %. The conclusions can provide some reference for the evaluation of shear instability of rock joints in surface and underground rock engineering.

Reconstruction of patella fractures with the tension band technique: A review on clinical results and tips and tricks

IntroductionThe goals of surgical treatment of patellar fractures are a biomechanically stable joint and congruent restoration of the retro patellar joint surface. Surgical treatment strategies for patellar fractures have evolved from tension band in combination with wire cerclages to new devices. MethodsThe modified anterior tension band (MATB) technique for fixation of patellar fractures consists of two longitudinal 1.8 mm Kirschner wires (K-wires) and an 18-gauge stainless steel wire looped in a figure-of-8 pattern over the anterior aspect of the patella. The K-wires should be inserted 5 mm from the anterior cortical surface of the patella, parallel in the coronal and sagittal planes. For mechanical reasons, the wire should be the closest to the anterior aspect of the bone. This construct converts the anterior tensile forces generated by the extensor mechanism and knee flexion into compressive forces on the anterior aspect of the fracture site. The MATB is the most widely accepted method of internal fixation for transverse and comminuted patellar fractures.Only a careful implementation of the MATB in all its phases will provide the best mechanical construct and the least aggressive construct for the soft tissues, allowing early re-education without complications. ResultsGood to excellent clinical results (64–100 %) have been reported with MATB for fixation of patellar fractures. Good to excellent range of knee motion and satisfactory results have been reported despite a high percentage (up to 60 %) of secondary procedures, mainly for removal of symptomatic hardware. ConclusionThis article provides an overview of the use and results of the MATB technique for patellar fractures and the means to improve results with this technique.

What Have We Learned in the Wrist Joint of Distal Radius Fracture through Wrist Arthroscopy?

Abstract Background Wrist arthroscopy is an efficient tool for the surgical treatment of distal radius fracture (DRF). It could show us the various conditions of the radiocarpal joint, its effectiveness seems to overwhelm that of fluoroscopy. Methods Since July 2005, we have performed wrist arthroscopy and plate presetting arthroscopic reduction technique (PART) for 141 extra-articular and 559 intra-articular DRFs and investigated various kinds of intra-articular conditions and advantages of wrist arthroscopy. Results The pathological conditions clarified and the advantages of PART in the surgical treatment of DRF are: (1) accurate reduction of intra-articular fragments is possible compared with fluoroscopic reduction, (2) intra-articular fragments (free body) undetected with radiograph and CT can be recognized, (3) screw protrusion into joint surface can be monitored, (4) intra-articular soft tissue injury associated with fracture can be evaluated and treated, and (5) debridement of joint hematoma can be performed. Severe complications such as tendon rupture, major neurovascular injury or compartment syndrome from arthroscopy were never encountered. Conclusions The volar locking plate fixation and simultaneous arthroscopic intervention is problematic because vertical traction must be applied and released during surgery. PART can overcome these difficulties and achieved good clinical results.

Exploring the impact of wire core diameter on microstructure and joint properties in ultrasonic wire harness welding

The present study investigates ultrasonic metal welding to manufacture 10 mm2 copper (Cu) wire joints with different core diameters. The primary purpose of this study is to explore the influence of wire core diameter on the performance of ultrasonic welded joints. Wire core diameter is positively correlated with the peeling resistance of the joint. Superior mechanical properties of the joint are achieved with an increased diameter of the wire core. The peeling strength of the welded joint of two wires with a wire core diameter of 0.25 mm reaches 306.8 N. Examining the welding temperature and assessing the joint's porosity reveals a significant impact of temperature on porosity. However, relying solely on porosity as a criterion for judging the overall forming quality of joints may be insufficient. Scanning electron microscope and energy-dispersive X-ray elemental analysis revealed that certain wires underwent plastic deformation at elevated temperatures without attaining atomic bonding. Additionally, the welded joint exhibits a compact structure externally and a more relaxed structure internally. The upper side of the joint in contact with the briquette and the lower side in contact with the welding head exhibit minimal gaps, while numerous gaps are evident in the middle of the joint. Furthermore, upon examining the fracture morphology, two distinct failure modes are identified at the joint surface of the conductor. The first involves the fracture of the wire core with a completely separated joint surface, resulting in poor mechanical properties of the joint. The second mode entails the ductile fracture of the wire core at the joint surface, indicating good mechanical properties of the joint.

Contribution of Musculoskeletal Ultrasound in the Diagnosis of Seronegative Rheumatoid Arthritis.

This is a study to investigate the value of musculoskeletal ultrasound for the early diagnosis of seronegative rheumatoid arthritis (SNRA); and to study the relationship between anti-cyclic citrullinated peptide antibody (anti-CCP) and the occurrence of bone erosion in rheumatoid arthritis (RA) detected by ultrasound. A total of 101 patients with RA or osteoarthritis (OA) admitted to the First Affiliated Hospital of Anhui Medical University from July 2022 to December 2023 were selected and divided into the SNRA group, the SPRA group, and the OA group. The patients' metacarpophalangeal joints, proximal interphalangeal joints, distal interphalangeal joints, and wrist joints of both hands were ultrasonically examined separately, and the extensor tendon, flexor tendon, synovium, joint surface, joint cavity, and bone surface were observed. The differences in the detection of joint effusion, bone erosion, and joint space narrowing were not statistically significant between SNRA group and OA group (P > .05), the differences in the detection of synovitis and tenosynovitis were statistically significant (P < .05). The mean levels of synovial hyperplasia grade and synovial blood flow grade between SNRA group and OA group were significantly different (P < .05). The differences in synovitis, tenosynovitis, joint effusion, and joint space narrowing were not statistically significant between SNRA and SPRA groups (P > .05), and the differences in bone erosion were statistically significant (P < .05). The mean levels of synovial hyperplasia grade and synovial blood flow grade between SNRA group and SPRA group were significantly different (P < .05). Logistic regression analysis showed that anti-CCP antibody was an influential factor for bone erosion in RA patients (P < .05). The ROC curve was plotted, and the optimal cut-off value of anti-CCP antibody was 356.5U/mL, at which time the AUC was 0.716, the sensitivity of diagnosing bone erosion was 0.714, the specificity was 0.694, and the Yoden index was 0.408. In summary, ultrasound is helpful for the early diagnosis of SNRA by evaluating the condition of joints, synovium, and tendon sheath, and when anti-CCP antibodies are positive, ultrasound is more likely to detect bone erosion. Ultrasound examination combined with anti-CCP antibody can further observe the joint lesions.