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Total joint arthroplasty (TJA) has significantly improved the quality of life for millions suffering from end-stage arthritis. However, periprosthetic joint infections (PJI) remain a serious complication, necessitating extensive interventions and prolonged antimicrobial treatments. The aging population is expected to lead to a rise in TJA cases, subsequently increasing the incidence of PJI, particularly in the elderly who face higher mortality rates. Current diagnostic methods for suspected PJI, such as radiographs and biochemical markers like CRP and ESR, exhibit limited sensitivity. Therefore, there is a critical need for a specific synovial fluid biomarker assay to enhance PJI diagnosis using specific SF-based assay. This study introduces a novel microfluidic chip with a paper-based aptamer-sandwich assay for the quantitative detection of HNP 1, a crucial PJI biomarker, in synovial fluid. The assay leverages the advantages of aptamers over antibodies, demonstrating high selectivity and affinity for target molecules. The integration of a nitrocellulose (NC) membrane onto the microfluidic platform represents a significant advancement, reducing background signals and simplifying the assay procedure without intricate procedure and pre-treatment. The NC membrane-based microfluidic device offers rapid, cost-effective, and highly sensitive detection of HNP 1, with a limit of detection of 0.5 mg L−1. The microfluidic device demonstrates exceptional performance, detecting up to four clinical samples in approximately 42 min on a single chip with 100 % accuracy, as confirmed by analysis of 12 clinical samples and comparison with "gold-standard". Moreover, the assay exhibits a wide dynamic range of 0.5–100 mg L-1, underscoring its potential as a powerful tool for PJI diagnosis in clinical settings. This work introduces a paper-based microfluidic system tailored for rapid HNP 1 detection using synovial fluid near joint region (and not serum via blood) for better diagnosis. The innovative paper-based aptamer-sandwich assay yields results within 42-min. Significantly, it boasts a wide dynamic range, detecting levels from an impressive 0.5 mg L-1, crucial in the 2.6 mg L-1 threshold region. This heightened sensitivity and expansive detection capability establish our assay as a leader in PJI diagnostics, promising unmatched precision and efficiency in clinical applications. Schematic representation of the automated paper-based aptamer sandwich assay for periprosthetic joint infection (PJI) detection. The microfluidic chip features a reaction zone utilizing an NC membrane as the paper substrate, along with a dual aptamer assay for efficient aptamer-sandwich formation. Detection is achieved via the PMT module and subsequent analysis using fluorescent microscopy to differentiate PJI-positive and negative synovial fluid (SF) samples. [Display omitted] • We devised a novel paper-based aptamer-sandwich assay integrated into an automated microfluidic platform to detect HNP 1. • 42-minute swift operated assay, streamlined pretreatment steps, no extra quenching methods needed. • Clinical samples assessed on chip; results compared to gold standard ELISA (designed for serum, adjusted for SF). [ABSTRACT FROM AUTHOR]

Introduction: Apoptosis dysregulation plays a substantial role in the pathophysiology of chronic inflammation and its related symptoms such as edema. Regulation of NF-ĸB activation is involved in apoptosis pattern change. The current study aimed at verifying the effects of local inflammation on edema and changes in apoptotic markers, and investigating the possible role of NF-ĸB in apoptosis pattern change during different stages of complete Freund's adjuvant (CFA)-induced knee arthritis in rats. Methods: A total of 96 male Wistar rats were divided into different experimental groups. Arthritis was evoked into the right knee articular joint. Changes made in knee edema were assessed by caliper on the days 0, 7, 14, and 21 of the study. Synovial NF-ĸB and levels of apoptotic markers were evaluated during different stages of the study using Western blot technique. Results: CFA injection caused intense edema during the whole study period. Synovial NF-ĸB level increased during the whole study period. The level of apoptotic markers increased during the acute phase of study. But during chronic phase, the apoptosis level decreased. Inh-NF-ĸB administration increased synovial apoptosis during the whole study period. Conclusion: It seems that apoptosis pattern change plays an important role in the progression and modulation of CFA-induced inflammation and its related symptoms. Also, it can be concluded that synovial NF-ĸB had a crucial role in synovial apoptosis change during the study period. [ABSTRACT FROM AUTHOR]

Some serious errors exist in the above paper. [ABSTRACT FROM AUTHOR]

The paper proposes a method based on a combination of the provisions of the phonon theory of liquid, V–T formalism, and Frenkel's theory of determining the P–T parameters of a liquid system, to determine the pressure and temperature values at which the transition from a denser liquid fraction to a less dense one occurs. Its use makes it possible to analyze the motion of fluid components in joint complexes and to determine their lifetime. It is also shown that at short time intervals, regardless of the physical state of the system, the components of the liquid move as independent particles, and their motion can be represented within the framework of the vibrational-hopping diffusion model. In this paper, the developed methodology is used to study the structural and dynamic properties of argon near the triple point on the liquid–gas coexistence curve. [ABSTRACT FROM AUTHOR]

Infection is an uncommon side effect of arthroscopic surgery, and this percentage is higher in anterior cruciate ligament reconstruction (ACLR) surgery, where graft and fixation devices are used. Infections can not only lead to high re-admission rates and poor functional recovery of the knee but can also have a significant negative impact on the patient's psychological and economic health, especially in athletes, as it can affect their sports career. It is important to be aware of the many risk factors, especially the manifestation of symptoms. These may sometimes be non-specific to the infectious pathology and common to other situations, such as the presence of a significant intra-articular hematoma. Septic arthritis after ACLR can occur at any time after surgery but typically presents acutely, while late manifestation is relatively rare. Diagnosis of infection is based on patient history, physical examination, laboratory parameters, and analysis of synovial fluid after joint aspiration, which is the gold standard for diagnosing post-operative infection. Once symptoms appear and the diagnosis seems certain, it is necessary to intervene quickly with arthroscopic debridement and long-term antibiotic treatment to try to save the graft and resolve the infectious situation to avoid graft failure and arthrofibrotic sequelae. The aim of this paper is to provide an overview of the epidemiology, pathogenesis, risk factors, clinical presentation, diagnostic evaluation, and current treatment guidelines of septic arthritis after ACLR surgery by analyzing recent literature, in particular meta-analyses and systematic reviews. [ABSTRACT FROM AUTHOR]

This paper presents a new form of a mathematical estimation of stochastic bio-hydrodynamic lubrication parameters for real human joint surfaces with phospholipid bilayers. In this work, the authors present the analytical and stochastic considerations, which are based on the measurements of human joint surfaces. The gap is restricted between two cooperating biological surfaces. After numerous experimental measurements, it directly follows that the random symmetrical as well as unsymmetrical increments and decrements of the gap height in human joints influence the hydrodynamic pressure, load-carrying capacity, friction forces, and wear of the cooperating cartilage surfaces in human joints. The main focus of the paper was to demonstrate the influence of variations in the expected values and standard deviation of human joint gap height on the hydrodynamic lubrication parameters occurring in the human joint. It is very important to notice that the new form of apparent dynamic viscosity of synovial fluid formulated by the authors depends on ultra-thin gap height variations. Moreover, evident connection was observed between the apparent dynamic viscosity and the properties of cartilage surface coated by phospholipid cells. The above observations indicate an indirect impact of stochastic changes in the height of the gap and the indirect impact of random changes in the properties of the joint surface coated with the phospholipid layers, on the value of hydrodynamic pressure, load carrying capacity and friction forces. In this paper the authors present a synthetic, comprehensive estimation of stochastic bio-hydrodynamic lubrication parameters for the cooperating, rotational cartilage bio-surfaces with phospholipid bilayers occurring in human joints. The new results presented in this paper were obtained taking into account 3D variations in the dynamic viscosity of synovial fluid, particularly random variations crosswise the film thickness for non-Newtonian synovial fluid properties. According to the authors' knowledge, the obtained results are widely applicable in spatiotemporal models in biology and health science. [ABSTRACT FROM AUTHOR]

Knee osteoarthritis is a common orthopedic disease with treatment difficulties, which has a high incidence rate in middle-aged and elderly people. Its pathological mechanism has not been fully understood. Current researches have found a strong correlation between obesity, abnormal lipid metabolism, and the occurrence and development of knee osteoarthritis. Synovial fluid of joints contains many metabolites and directly participates in the regulation of intra-articular metabolism, which can directly reflect the local lipid metabolism status of joints. The lipid metabolism profile in the synovial fluid of patients with knee osteoarthritis includes a variety of fatty acids and their related metabolites such as carnitine, acetyl coenzyme A, as well as a variety of phospholipids and adipo-cytokines such as adiponectin, leptin, and resistin. Among them, lipids such as arachidonic acid, some short-chain saturated fatty acids, and related metabolites may have a bidirectional regulatory function in the development of KOA, which is worthy of in-depth study. In this paper, we review the literature on the characteristics of lipid metabolism in synovial fluid of patients with knee osteoarthritis, with the aim of clarifying the correlation between lipid metabolism in synovial fluid and the occurrence and development of knee osteoarthritis, and providing some new ideas for the prevention and treatment of knee osteoarthritis. [ABSTRACT FROM AUTHOR]

Fundamental knowledge about in vivo kinematics and contact conditions at the articulating interfaces of total knee replacements are essential for predicting and optimizing their behavior and durability. However, the prevailing motions and contact stresses in total knee replacements cannot be precisely determined using conventional in vivo measurement methods. In silico modeling, in turn, allows for a prediction of the loads, velocities, deformations, stress, and lubrication conditions across the scales during gait. Within the scope of this paper, we therefore combine musculoskeletal modeling with tribo-contact modeling. In the first step, we compute contact forces and sliding velocities by means of inverse dynamics approach and force-dependent kinematic solver based upon experimental gait data, revealing contact forces during healthy/physiological gait of young subjects. In a second step, the derived data are employed as input data for an elastohydrodynamic model based upon the finite element method full-system approach taking into account elastic deformation, the synovial fluid's hydrodynamics as well as mixed lubrication to predict and discuss the subject-specific pressure and lubrication conditions. [ABSTRACT FROM AUTHOR]

Rheumatoid arthritis (RA) is a chronic autoimmune disease of unexplained causes. Its pathological features include synovial tissue hyperplasia, inflammatory cell infiltration in joint cavity fluid, cartilage bone destruction, and joint deformation. C–C motif chemokine ligand 3 (CCL3) belongs to inflammatory cell chemokine. It is highly expressed in inflammatory immune cells. Increasingly, studies have shown that CCL3 can promote the migration of inflammatory factors to synovial tissue, the destruction of bone and joint, angiogenesis, and participate in the pathogenesis of RA. These symptoms indicate that the expression of CCL3 is highly correlated with RA disease. Therefore, this paper reviews the possible mechanism of CCL3 in the pathogenesis of RA, which may provide some new insights for the diagnosis and treatment of RA. [ABSTRACT FROM AUTHOR]

Purpose: This paper presents tribological and rheological analysis results of artificial synovial fluid base solutions. Special attention was paid to polyacrylamide preparations with different molecular weights and concentrations. Methods: Tribological tests were conducted using the Al2O3-CoCrMo friction pair in the presence of investigated lubricants. Confocal microscopy was used to analyze and assess of volume, depth, and width of wear traces. Moreover, the viscosity and viscoelasticity tests of analyzed solutions were carried out. The rheological measurements were focused on the oscillatory tests, which allowed us to determine the elasticity modulus (G') and viscosity (G"). Results: Viscoelastic nature of the tested preparations depends on the strain rate. It has been shown that elastic properties dominate at higher frequencies. The molecular weight of the polymer has a particular influence on these properties. The most promising results were obtained for 6% and 8 % high molecular weight polyacrylamide compositions. Conclusions: However, all tested polyacrylamide solutions show better rheological and tribological characteristics than commercial preparation based on hyaluronic acid. [ABSTRACT FROM AUTHOR]

This article explores the role of T helper cells in autoimmune diseases and the need for more effective treatment strategies. The authors specifically focus on autoreactive CD4+ T helper cells, particularly the T follicular helper subset, which promote the production of autoantibodies. They also discuss the imbalance between pathogenic peripheral T helper cells and tissue-resident Tregs in autoimmune diseases. The article highlights the importance of further research to develop targeted therapies for controlling autoimmune diseases. Additionally, the document provides a summary of various studies and reviews on the role of T helper cells in specific autoimmune diseases, aiming to contribute to the understanding of T cell involvement and potential therapeutic targets. [Extracted from the article]

Background: Definitions are important in healthcare. Unfortunately, problems can be found withall existing definitions of manipulation. Methods: This paper derives a set of eligibility criteria from prior definitions of manipulation to inform what should (and should not) be incorporated within a valid definition. These criteria were then used to select components from currently available empirical data to create a new definition. Results: The resulting definition of manipulation is: "Separation (gapping) of opposing articular surfaces of a synovial joint, caused by a force applied perpendicularly to those articular surfaces, that results in cavitation within the synovial fluid of that joint." The corresponding definition for the mechanical response of a manipulation is: "Separation (gapping) of opposing articular surfaces of a synovial joint that results in cavitation within the synovial fluid of that joint." In turn, the action of a manipulation can be defined as: "A force applied perpendicularly to the articular surfaces." Conclusions: We believe these definitions to be valid (derived from and consistent with all available empirical data), complete (containing all necessary components), minimally sufficient (minimal redundancy, and sufficient to distinguish manipulation from other physical interventions), and robust (able to withstand important limitations embodied within sensible eligibility criteria). It is hoped that the simplicity and clarity of these definitions, and the transparency of their formation, will encourage their wide adoption in clinical, research, educational and professional settings. [ABSTRACT FROM AUTHOR]

Septic arthritis is a synovial fluid and joint tissue infection with significant morbidity and mortality risk if not diagnosed and treated promptly. The most common pathogen to cause septic arthritis is Staphylococcus aureus, a Gram-positive bacterium. Although diagnostic criteria are in place to guide the diagnosis of staphylococcal septic arthritis, there is a lack of adequate sensitivity and specificity. Some patients present with atypical findings which make it difficult to diagnose and treat in time. In this paper, we present the case of a patient with an atypical presentation of recalcitrant staphylococcal septic arthritis in a native hip complicated by uncontrolled diabetes mellitus and tobacco usage. We review current literature on diagnosing S. aureus septic arthritis, novel diagnostic technique performance to guide future research and assist clinical suspicion, and current S. aureus vaccine development for at-risk patients. [ABSTRACT FROM AUTHOR]

Chitosan–collagen blends have been widely applied in tissue engineering, joints diseases treatment, and many other biomedical fields. Understanding the affinity between chitosan and collagen type II is particularly relevant in the context of mechanical properties modulation, which is closely associated with designing biomaterials suitable for cartilage and synovial fluid regeneration. However, many structural features influence chitosan's affinity for collagen. One of the most important ones is the deacetylation degree (DD) in chitosan and the hydroxylation degree (HD) of proline (PRO) moieties in collagen. In this paper, combinations of both factors were analyzed using a very efficient molecular dynamics approach. It was found that DD and HD modifications significantly affect the structural features of the complex related to considered types of interactions, namely hydrogen bonds, hydrophobic, and ionic contacts. In the case of hydrogen bonds both direct and indirect (water bridges) contacts were examined. In case of the most collagen analogues, a very good correlation between binding free energy and DD was observed. [ABSTRACT FROM AUTHOR]

Degradation of the articular cartilage (AC) structure due to osteoarthritis significantly influences its friction and lubrication mechanisms. Injection with exogenous hyaluronic acid (HA) is one of the ways to slow down the progress of these changes. The present paper aims to determine the effect of HA on the friction and lubrication processes of the synovial joint model. The main emphasis is placed on the effect of HA molecular weight (MW) on the coefficient of friction (COF) and the interactions between HA and other constituents of synovial fluid (SF). Frictional measurements between the AC surface and the glass were performed with simultaneous in situ observation of the contact zone by fluorescence microscopy. Using this methodology, a decrease in AC COF with an increase in the fluorescence intensity emitted from contact with HA was observed, while the phenomenon was found to be MW-dependent. These findings demonstrate that high-MW HA is more effective within a resumption of healthy AC lubrication due to a better adhesion to the AC surface. [ABSTRACT FROM AUTHOR]

The possibility of using magnesium (Mg) alloys in biomedical field gives a lot of advantages. Their mechanical properties are more similar to the bone tissue than conventional metals and make the Mg a promising material for bio-engineering applications. The major restriction of Mg and its alloys is the degradation in organic human environment. Nevertheless, if implants or their components do not have to be permanent, there is the possibility to exploit the benefits provided by use of Mg. The anodic behaviour of Mg is enhanced when it is coupled with a nobler metal like titanium (Ti). The idea to couple these different materials to create a hybrid joint is proposed in this paper. This solution allows to have a wide range of improvements for the patient, for instance a quicker tissue regeneration due to release of Mg ions and a less pain related to the implant development due to degradation of non-permanent screws. The Mg corrosion rate control through the use of proper coatings on the metal surface is essential in this scenario. The knowledge of the weight loss value of the electrolytic cell is necessary to design a right coating. For this purpose, a macro galvanic corrosion (GC) numerical model of a joint composed by Ti6Al4V and two different Mg alloys, such as AZ31 and AZ91, is proposed in this study and simulations are carried out by using a FEM software. In this work the corrosion phenomenon of the Mg alloys was investigated in order to increase the opportunities of using hybrid joints in biomedical field exploiting their benefits through appropriate precautions, mostly related to coatings which have to be properly designed. [ABSTRACT FROM AUTHOR]

Viscosupplementation by intra-articular (i.a.) injection of the non-sulfated glycosaminoglycan (GAG) hyaluronic acid (HA) is a conservative therapy widely accepted in clinical practice for the management of osteoarthritis (OA) and joint diseases. The aim of viscosupplementation is to restore the rheological properties of the synovial fluid to relieve joint inflammation and pain and improve joint function through a chondroprotective effect. However, there is a range of hyaluronic acid products for OA that differ in preparation, molecular weight, rheological characteristics and concentration, and different i.a. formulations are more suited to particular patient populations and clinical situations, in part because of anatomical differences between joints. This paper focuses on innovative hybrid cooperative complexes of high and low molecular weight hyaluronic acid (HA-HL) and hyaluronic acid plus sodium chondroitin (HA-SC) that have been developed. Both products are formulated with pharmaceutical-grade, highly purified hyaluronic acid obtained with a multi-step biofermentation process, with properties that make them suitable across a range of degenerative joint diseases. They represent progress in building on the symptomatic and functional benefits of viscosupplementation in joint disease, with the additional beneficial effect of treating the patient with a high concentration of GAGs by a low number of injections. Here, we review the clinical evidence for the efficacy of a hybrid cooperative compound of HA-HL in various degenerative joint diseases, which suggests a synergistic effect of the different molecular weight hyaluronans that together more closely mimic the physiological composition of synovial fluid. Similarly, the evidence shows that HA-SC is safe, effective, and well tolerated in hip OA, with rapid and clinically significant improvements in pain symptoms and functionality. Such innovations in viscosupplementation expand the usefulness of the modality in the management of OA and other joint diseases, complemented by a lack of systemic or local side effects that allow the concurrent use of other drugs if needed. [ABSTRACT FROM AUTHOR]

Background: Current guidance for the management of septic arthritis is limited to large joints and, therefore, unspecific to the small joints of the hand, which may present differently, require different diagnostic approaches, and have different complications. The aim of this article was to review current treatment trends for the management of small joint septic arthritis (SJSA) of the hand and offer guidelines for its management. Methods: A systematic review was carried out according to PRISMA guidelines and a survey distributed to Fellows of the British Society for Surgery of the Hand to establish expert opinion. The review and survey were combined to present a set of specific SJSA of the hand infection guidelines. Results: All 20 included studies recommended physical drainage of infected joint fluid; subsequent lavage and early antibiotic therapy, with physiotherapist-guided joint mobilisation. Statistical analysis of the 77 responses to our survey revealed that (in order of preference) the diagnosis was made by history and examination, blood tests, joint aspiration and vital signs; and for interventions: joint elevation and intravenous antibiotics; then joint washout repeated within 48 hours, if necessary. Conclusions: Small joint infection differs from large joint infection because it is difficult to obtain joint aspirate without damaging or opening the joint. We, therefore, recommend utilising exclusion blood tests, imaging and the clinical picture to establish the diagnosis and implement early treatment and rehabilitation. Level of Evidence: Level III [ABSTRACT FROM AUTHOR]

This paper studies the deviation rate between natural knee cartilage and polyvinyl alcohol hydrogel artificial cartilage under different compression conditions; when the artificial cartilage is subjected to loads of 10 N, 30 N, 50 N, 70 N, and 90 N, the relationship between Poisson's ra tio and the stress; simulates the stress-strain/ relationship of adding macromolecular activator to synovial fluid, pure polyvinyl alcohol hydrogel and porous polyvinyl alcohol hydrogel subjected to different compression amount and compression time. The results show that under the same amount of compression, the deviation rates of Mises stress, maximum principal stress and maximum principal strain of the contact surface of artificial cartilage and natural cartilage are stable at 2.996%, 3.912% and 3.67%, respectively. The stress-strain/ deviation rate of the artificial cartilage on the contact surface does not change with time and compression after increasing to a certain value; under the same load, the higher the concentration, the lower the Poisson's ratio; 20% polyvinyl alcohol hydrogel under a load of 90 N, the artificial cartilage bears a load of 10 N to 90 N, and its Poisson's ratio decreases from 0.6 to 0.425. Compared with adding DPPC phospholipid or γ-globulin/ alone, adding DPPC phospholipid and γ-globulin/ to synovial fluid has better lubricating properties. [ABSTRACT FROM AUTHOR]

Objectives. To describe existing techniques of US-guided synovial biopsy (USG-SB) and critically appraise the literature on this technology through the OMERACT filter. Methods. USG-SB techniques are described and compared. A systematic literature search of PubMed and Embase was performed for original research reports including US and SB. The subjects, procedure protocols and reported results were analysed. A future research agenda is proposed. Results. USG-SB can be performed using a portal-and-forceps or a dedicated semi-automatic guillotine-type biopsy needle approach. Of 50 reports identified, 7 were included in the review. Large, intermediate and small joints were all amenable to USG-SB. We found great heterogeneity with regard to indications for and definition of a successful procedure and of synovitis. Adverse events were assessed in most papers with an overall major complication rate of 0.4%. However, there was a lack of construct validity using a histological comparator. Relatively few papers reported details on the technique used, tissue processing, synovitis scoring and blinding for tissue analysis. Conclusion. USG-SB can be regarded as a valuable tool for large-scale synovial tissue sampling. Standardization of the techniques of USG-SB and tissue processing is needed. Future research should focus on the reliability, responsiveness and feasibility of this procedure in prospective studies. [ABSTRACT FROM AUTHOR]

Introduction: This study tried to ascertain (1) the accuracy of synovial fluid white blood cell count and polymorphonucleate percentage in the diagnosis of periprosthetic hip and knee infections, (2) which test yielded superior test performance, and (3) the influence on diagnostic accuracy of study characteristics such as patient number, study design, study level, anatomic site, and threshold value.Methods: A systematic search was conducted including papers assessing more effective cutoffs for synovial fluid tests, having comparative design, evaluating an exclusive cohort of hip or knee prostheses, including a clear definition of infected cases, and reporting sufficient data for the calculation of true-positive, false-positive, false-negative, and true-negative.Results: A total of 375 articles were collected and, given the inclusion criteria, ten manuscripts were included. These studies assessed 1155 hip prostheses (276 infected cases) and 1235 knee prostheses (401 infected cases). The specificity of synovial fluid white blood cell count was significantly increased by using the threshold value ≥ 3000 cell/μL (p = 0.006); the sensitivity of polymorphonucleate percentage was significantly higher in detecting knee infections (p = 0.034).Discussion: Both tests had a high specificity and sensitivity in detecting periprosthetic joint infections, and no clear superiority of one over the other existed. Furthermore, cutoff and anatomic site significantly influenced synovial fluid white blood cell count and polymorphonucleate percentage, respectively.Conclusion: Synovial fluid analysis is adequate in differentiating patients with periprosthetic hip and knee infections. Our data confirms international guidelines suggesting the use of 3000 cell/μL as cutoff threshold for synovial fluid white blood cell count. Since an anatomic site effect has been demonstrated, the goal of future studies will be to identify different cutoffs for hip and knee prostheses. [ABSTRACT FROM AUTHOR]

Rheumatoid arthritis (RA) is an autoimmune disorder that typically affects people between 23 and 60 years old causing chronic synovial inflammation, symmetrical polyarthritis, destruction of large and small joints, and chronic disability. Clinical diagnosis of RA is stablished by current ACR-EULAR criteria, and it is crucial for starting conventional therapy in order to minimize damage progression. The 2010 ACR-EULAR criteria include the presence of swollen joints, elevated levels of rheumatoid factor or anti-citrullinated protein antibodies (ACPA), elevated acute phase reactant, and duration of symptoms. In this paper, a computer-aided system for helping in the RA diagnosis, based on quantitative and easy-to-acquire variables, is presented. The participants in this study were all female, grouped into two classes: class I, patients diagnosed with RA (n = 100), and class II corresponding to controls without RA (n = 100). The novel approach is constituted by the acquisition of thermal and RGB images, recording their hand grip strength or gripping force. The weight, height, and age were also obtained from all participants. The color layout descriptors (CLD) were obtained from each image for having a compact representation. After, a wrapper forward selection method in a range of classification algorithms included in WEKA was performed. In the feature selection process, variables such as hand images, grip force, and age were found relevant, whereas weight and height did not provide important information to the classification. Our system obtains an AUC ROC curve greater than 0.94 for both thermal and RGB images using the RandomForest classifier. Thirty-eight subjects were considered for an external test in order to evaluate and validate the model implementation. In this test, an accuracy of 94.7% was obtained using RGB images; the confusion matrix revealed our system provides a correct diagnosis for all participants and failed in only two of them (5.3%). Graphical abstract. [ABSTRACT FROM AUTHOR]

Aim and objective: The concentration of lipoproteins and apolipoprotein are extremely low in the synovial fluid of any healthy person as compared to the concentrations in plasma. However, in the synovial fluid of any diseased patient the amount of cholesterol and lipids is sharply increased. The current review defines the role of various apolipoproteins and lipoproteins and their constituent subfractions in the synovial fluid embarking its principal role in rheumatoid arthritis. It also explains the need to define synovial fluid lipids, lipoprotein particle subfractions and their constituent apolipoproteins in synovial fluid. Materials and methods: Various research and review articles highlighting the role of apolipoproteins and lipoproteins were procured from medical websites mainly Pubmed, Medline, Science Direct, etc., and studied for the writing of the review paper. Conclusion: Mainly apolipoproteins A-1, B and E are prominently increased in chronic inflammatory joint disorders. Several theories have been proposed to understand the source of increase of lipids and apolipoproteins in synovial fluid of the diseased patients compared to healthy individuals, yet the precise mechanism is still not lucid. Lipoproteins are believed to play both functional role and pathological role in the synovial fluid. The activated T-lymphocytes in patients of RA lead to activation of inflammatory cytokines such as tumor necrosis factor and interleukins which embark to be the principal mechanism for induction of the disease. It can be thus concluded that the apolipoproteins prevent the activation of monocytes by blocking their contact of activation and thus play critical role in management of RA by inhibiting the production of proinflammatory cytokines. [ABSTRACT FROM AUTHOR]

Hip joint replacements represent the most effective way of treatment for patients suffering from joint diseases. Despite the rapid improvement of implant materials over the last few decades, limited longevity associated with wear-related complications persists as the main drawback. Therefore, improved tribological performance is required in order to extend the service life of replacements. The effect of surface texturing of ultra-high molecular weight polyethylene (UHMWPE) acetabular cup was investigated in the present study. Unique tilling method was utilized for manufacturing the dimples with controlled diameter and depths on the contact surface of the cup. The experiments with four commercial femoral components and two model lubricants were realized. The main attention was paid to a coefficient of friction considering the differences between the original and the dimpled cups. Results showed remarkable lowering of friction, in general. Focusing on the simulated human synovial fluid, friction was reduced by 40% (alumina ceramic), 38.8% (zirconia toughened ceramic), 25.5% (metal), and 9.9% (oxinium). In addition, the dimples helped to keep the friction stable without fluctuations. To conclude, the paper brings a new insight into frictional behaviour of the hip replacements during running-in phase which is essential for overall implant lifespan. It is believed that proper surface texturing may rapidly improve the life quality of millions of patients and may lead to considerable financial savings. [ABSTRACT FROM AUTHOR]

The analysis of synovial fluid is an important method in diagnosing and handling septic arthritis. To achieve a quick diagnosis could be a great advantage in the therapy. The differential scanning calorimetry (DSC) proved to be a useful technique in the differential diagnosis of tumors using blood plasma or sera. The aim of this paper is to show up some characteristic thermal parameters in the diagnosis of different grades of arthritis, which are in good agreement with the severity of disease checked by conventional X-ray supported grading. To follow the effect of different bacterial strains, the synovial fluids were inoculated by three types of bacterial strains (with 103–105 CFU mL−1 concentrations) at 37 °C and stored trough 24 h. After that, they were denatured in 20–90 °C temperature range with 0.3 K min−1 scanning rate. The change in the maximum denaturation temperature (Tm) and calorimetric enthalpy (∆H) monitored the severity of sepsis and depended on the type of bacteria. The proliferation characteristics of bacteria should be strain specific. The synovial fluid samples inoculated with the most frequently occurring bacteria were monitored in isotherm mode (isoperibol calorimeter) at 37 °C up to the end of the proliferation. The isoperibolic scans clearly demonstrated specific, concentration-dependent representative curves in case of each bacterium (duration of proliferation, maximum of proliferation rates, etc.). Therefore, thermal analysis of human synovial fluid samples by DSC or isoperibolic calorimetry could be a useful tool in the staging of osteoarthritis and the diagnostics of septic arthritis. [ABSTRACT FROM AUTHOR]

The frictional heat generated during the operation of the joint prosthesis in vivo could change the corrosion resistance of the prosthesis material. In this paper, the corrosion behavior of three medical alloys at different synovial fluid temperatures was analyzed using electrochemical measurement technology. Furthermore, the scanning electron microscope and energy‐dispersive spectrometer were used to characterize the surface morphology and composition of the alloys after long‐term immersion. The results show that increasing temperature causes the open‐circuit potential of titanium alloy to shift negatively and the corrosion tendency to increase. The increasing temperature leads to the decrease of activation energy of titanium alloy, which in turn results in the increase of corrosion current density and accelerated corrosion. The results of Nyquist curves confirmed that the radius of the capacitive arc decreased with the increase of temperature, indicating the deterioration of corrosion resistance. The CoCrMo alloy shows the same regularity as the titanium alloy in 0.9% NaCl, though no obvious regularity in 25% newborn bovine serum; this may be related to the complexity of the corrosion system. [ABSTRACT FROM AUTHOR]

Rheumatoid arthritis is an autoimmune disease characterized by inflammation in the synovial fluid within the synovial joint connecting two contiguous bony surfaces. The inflammation diffuses into the cartilage adjacent to each of the bony surfaces, resulting in their gradual destruction. The interface between the cartilage and the synovial fluid is an evolving free boundary. In this paper we consider a two-phase free boundary problem based on a simplified model of rheumatoid arthritis. We prove global existence and uniqueness of a solution, and derive properties of the free boundary. In particular it is proved that the free boundary increases in time, and the cartilage shrinks to zero as t → ∞ , even under treatment by a drug. It is also shown in the reduced one-phased problem, with cartilage alone, that a larger prescribed inflammation function leads to a faster destruction of the cartilage. [ABSTRACT FROM AUTHOR]

Shoulder arthroplasty is a common treatment for shoulder arthritis. Prosthetic joint infection of the shoulder (PJIS) is a debilitating complication to the patient and the healthcare system. Incidence of infection is 0.98–5% for primary arthroplasty. The mean hospital cost for two-stage revision was approximately $35,824. The aim of this paper is to review the recent literature and collate the latest evidence to aid diagnosis and treatment of this serious complication. A literature review was performed using PubMed and Google Scholar databases. A search strategy was adopted using the keywords: 'infection' AND 'shoulder arthroplasty' OR 'total shoulder arthroplasty'OR 'TSA' OR 'reverse shoulder arthroplasty' OR 'RSA' OR 'rTSA'. This initial search resulted in 349 articles. A PRISMA flowchart process was followed. Duplicates were removed, screening was performed and the resulting full texts were analysed and further excluded, leaving 46 articles suitable for inclusion. A PICO search strategy was also used. Risk factors for PJIS include procedure type, trauma indications and patient factors. The organism commonly isolated is Cutebacterium acnes, which makes diagnosis challenging due to its indolent nature. Investigations include biochemical tests, synovial aspirate, tissue cultures and radiological examinations. Treatment depends on the depth of the infection and the patient requirements. Medical treatment with antibiotics to local debridement, cement spacer and revision arthroplasty have all been described in the literature. A multidisciplinary decision is made on the microbiological evidence and patient factors. PJIS is a rare but potentially devastating complication of shoulder arthroplasty and diagnosis is often challenging. There has been much research performed recently, providing more evidence on how to optimise management. [ABSTRACT FROM AUTHOR]

Gas-water two-phase flow process widely exists in petroleum, chemical and other industrial processes, which is intricate, manifested by dynamic evolution of fluid structures and real-time fluctuation of flow parameters. Detailed description and real-time monitoring of flow status are of great significance to safe operation of industry processes. In this paper, a monitoring framework jointly mining the fluid knowledge and latent property behind multi-sensor data is proposed to address the issues of uncertainty and sample scarcity in transitional flow statuses, which enables real-time monitoring on structural evolution and parameter change of flow process. Firstly, the shared iterative algorithm with multi-task weight discovery is proposed to establish the relative semantic description system to characterize flow process knowledge by mining the relationship between multi-sensor data and different fluid semantic properties, which is helpful for interpretable monitoring of flow status structure and parameter information. Secondly, latent properties mined from multi-sensor data by sparse exponential discriminant analysis contribute to flow characterization completeness and discrimination. Thirdly, the process knowledge and latent information of flow status is transformed into different degrees of describable semantic and latent properties, which obtain relative representations of flow status in the joint description space realized by rank support vector machine. The results demonstrate that the method enables precise monitoring and detailed description of typical and uncertain flow statuses in the absence of transitional flow status modeling samples. [ABSTRACT FROM AUTHOR]

Objectives: To develop a protocol for largescale analysis of synovial fluid proteins, for the identification of biological networks associated with subtypes of osteoarthritis. Methods: Synovial Fluid To detect molecular Endotypes by Unbiased Proteomics in Osteoarthritis (STEpUP OA) is an international consortium utilising clinical data (capturing pain, radiographic severity and demographic features) and knee synovial fluid from 17 participating cohorts. 1746 samples from 1650 individuals comprising OA, joint injury, healthy and inflammatory arthritis controls, divided into discovery (n = 1045) and replication (n = 701) datasets, were analysed by SomaScan Discovery Plex V4.1 (>7000 SOMAmers/proteins). An optimised approach to standardisation was developed. Technical confounders and batch-effects were identified and adjusted for. Poorly performing SOMAmers and samples were excluded. Variance in the data was determined by principal component (PC) analysis. Results: A synovial fluid standardised protocol was optimised that had good reliability (<20% co-efficient of variation for >80% of SOMAmers in pooled samples) and overall good correlation with immunoassay. 1720 samples and >6290 SOMAmers met inclusion criteria. 48% of data variance (PC1) was strongly correlated with individual SOMAmer signal intensities, particularly with low abundance proteins (median correlation coefficient 0.70), and was enriched for nuclear and non-secreted proteins. We concluded that this component was predominantly intracellular proteins, and could be adjusted for using an 'intracellular protein score' (IPS). PC2 (7% variance) was attributable to processing batch and was batch-corrected by ComBat. Lesser effects were attributed to other technical confounders. Data visualisation revealed clustering of injury and OA cases in overlapping but distinguishable areas of high-dimensional proteomic space. Conclusions: We have developed a robust method for analysing synovial fluid protein, creating a molecular and clinical dataset of unprecedented scale to explore potential patient subtypes and the molecular pathogenesis of OA. Such methodology underpins the development of new approaches to tackle this disease which remains a huge societal challenge. [ABSTRACT FROM AUTHOR]

Simple Summary: Canine immune-mediated polyarthritis is a common disease that affects young dogs. This study aims at assessing whether leflunomide as add-on treatment to steroids would reduce the rate of relapse and improve survival in dogs with the disease. However, the results of this study suggest that there was no difference in outcomes between dogs that received or did not receive the drug as an add-on therapy. This could provide another step in understanding the nature of immune-mediated diseases and assist practicing veterinarians in making informed decisions about the most appropriate treatment for these conditions. Immune-mediated polyarthritis (IMPA) has a relatively high relapse rate compared to other immune-mediated diseases. Leflunomide is frequently used to treat dogs with IMPA in conjunction with prednisolone. This retrospective cohort study aimed to evaluate the therapeutic efficacy of leflunomide as an adjunctive therapy to prednisolone in reducing relapse and mortality rates in dogs diagnosed with IMPA in Australia. The medical records of client-owned dogs diagnosed with IMPA at a specialist referral hospital in Southeast Queensland from 2017 to 2024 were reviewed. A total of 93 dogs were included in this study, divided into two groups based on the treatment received: Group PRED, consisting of 53 dogs treated with prednisolone as the sole immunosuppressive agent, and Group L+PRED, consisting of 40 dogs that received leflunomide as adjunctive therapy alongside prednisolone. Data collected included breed, age, weight, sex, serum C-reactive protein concentration, results of synovial fluid analysis and microbial culture, treatment protocol, relapse rates and time to relapse, and mortality rates. There was no difference in relapse or mortality rates, time to relapse, nor time to discontinue prednisolone between the PRED and L+PRED groups. The L+PRED group had higher body weights and lower prednisolone dose rate at discharge compared to those in the PRED group. This study demonstrated that the use of leflunomide as an adjunctive therapy to prednisolone for the treatment of dogs with IMPA had no improved outcomes, reduced relapse rates, or shortening in the duration of prednisolone therapy when compared to dogs receiving prednisolone monotherapy. [ABSTRACT FROM AUTHOR]

Background: Anterior cruciate ligament (ACL) injury is frequently associated with injuries to other parts of the knee, including the menisci and articular cartilage. After ACL injury and reconstruction, there may be progressive chondral degradation. Biomarkers in blood, urine, and synovial fluid can be measured after ACL injury and reconstruction and have been proposed as a means of measuring the associated cellular changes occurring in the knee. Purpose: To systematically review the literature regarding biomarkers in urine, serum, or synovial fluid that have been associated with an outcome measure after ACL reconstruction. Study Design: Systematic review; Level of evidence, 3. Methods: This review was performed according to the PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) guidelines. The MEDLINE, Embase, CINAHL, and Web of Science databases were searched to identify studies published before September 2023 that reported on patients undergoing ACL reconstruction where a biomarker was measured and related to an outcome variable. Of 9360 results, 16 studies comprising 492 patients were included. Findings were reported as descriptive summaries synthesizing the available literature. Results: A total of 45 unique biomarkers or biomarker ratios were investigated (12 serum, 3 urine, and 38 synovial fluid; 8 biomarkers were measured from >1 source). Nineteen different outcome measures were identified, including the International Knee Documentation Committee Subjective Knee Form, Knee injury and Osteoarthritis Outcome Score, numeric pain scores, radiological outcomes (magnetic resonance imaging and radiography), rates of arthrofibrosis and cyclops lesions, and gait biomechanics. Across the included studies, 17 biomarkers were found to have a statistically significant association (P <.05) with an outcome variable. Serum interleukin 6 (s-IL-6), serum and synovial fluid matrix metalloproteinase-3 (s-MMP-3 and sf-MMP-3), urinary and synovial fluid C-terminal telopeptide of type 2 collagen (u-CTX-II and sf-CTX-II), and serum collagen type 2 cleavage product (s-C2C) showed promise in predicting outcomes after ACL reconstruction, specifically regarding patient-reported outcome measures (s-IL-6 and u-CTX-II), gait biomechanical parameters (s-IL-6, sf-MMP-3, s-MMP-3, and s-C2C), pain (s-IL-6 and u-CTX-II), and radiological osteoarthritis (ratio of u-CTX-II to serum procollagen 2 C-propeptide). Conclusion: The results highlight several biomarkers that have been associated with clinically important postoperative outcome measures and may warrant further research to understand if they can provide meaningful information in the clinical environment. [ABSTRACT FROM AUTHOR]

Hyaluronic acid (HA) is a glycosaminoglycan composed of D-glucuronic acid and N-acetylglucosamine with an up-to-several-million-Daltons chain-length responsible for the lubricating properties of the temporomandibular joint (TMJ) synovial fluid. Arthritis results in the predominance of HA degradation over synthesis leading to temporomandibular disorders (TMDs). TMD injection treatments are divided into HA supplementation and platelet-rich plasma (PRP) inflammation suppression. We questioned whether either approach lubricated the TMJ better and answered it in a two-arm equal-allocation trial with a non-concurrent active treatment control (two groups of 39 patients each). HA statistically significantly improved (p < 0.01) and PRP did not statistically significantly change (0.06 ≤ p ≤ 0.53) articular mobility compared to baselines in 128 TMJs. Statistically significant inter-group discrepancies were observed for abduction (MD = −4.05 mm; SE = 1.08; p = 0.00; d = −0.85) and protrusion (MD = −0.97 mm; SE = 0.43; p = 0.03; d = −0.51) but not for rightward (MD = −0.21; SE = 0.43; p = 0.63; d = −0.11) and leftward (MD = −0.30; SE = 0.42; p = 0.47; d = −0.16) movements. HA supplementation proved superior to PRP autografting in ad hoc TMJ lubrication and hence is more appropriate in hypomobile TMD cases of symptomatic treatment. [ABSTRACT FROM AUTHOR]

Osteoarthritis (OA) is a chronic, progressive, degenerative joint disease characterized by joint pain, stiffness, and limited movement. It presents significant intra- and inter-individual variability—in particular, between genders. Recent research has increasingly focused on the role of adipokines—especially leptin, adiponectin, and resistin—in the development of OA. Adipokines, peptide hormones primarily secreted by adipose tissue, are involved in crucial physiological processes related to metabolism and immunity. They can also impact bone and cartilage turnover by interacting with joint cells such as osteoblasts, osteoclasts, chondrocytes, and mesenchymal stem cells, thereby linking inflammation with bone cartilage homeostasis. This review aims to elucidate the structure and functions of various adipokines, their serum and synovial levels, and their association with clinical presentation and radiographic progression in OA patients, with a focus on differences between sexes. A narrative literature review was conducted using three databases specifically analyzing sex differences. OA patients generally show elevated serum and synovial levels of leptin, chemerin, and visfatin, as well as high plasma levels of resistin and visfatin. In contrast, synovial levels of adiponectin and omentin are reduced in OA patients compared to healthy individuals, with an inverse relationship to disease severity, suggesting a potential protective role. Resistin and leptin were positively correlated with pain severity and radiographic progression, while adiponectin's role in OA remains controversial. Regarding sex differences, male OA patients exhibited higher serum levels of leptin, chemerin, and omentin compared to healthy controls, with a positive correlation to the BMI and estrogen levels, potentially explaining the sexual dimorphism observed in this condition. Studies on visfatin and lipocalin did not reveal significant differences in synovial or serum levels between the sexes. The role of resistin remains controversial. Adipokines influence the joint microenvironment and contribute to the progression of osteoarthritis (OA). However, the precise biological mechanisms are not yet fully understood due to the complex interactions between the metabolic, mechanical, and immune systems. Further research is needed to clarify their roles in OA and to identify targeted therapies for managing this degenerative disease. [ABSTRACT FROM AUTHOR]

Background: Synovial fluid proteins had been applied as diagnostic biomarkers for periprosthetic joint infection (PJI) in recent research papers. Thus, this meta-analysis aimed to estimate the diagnostic efficiency of synovial fluid α-defensin and leukocyte esterase (LE) for PJI. Methods: We conducted our systematic review by searching the keywords in online databases such as PubMed, Embase, Cochrane, Elsevier, Springer, and Web of Science from the time of database inception to October 2018. Inclusion criteria were as follows: patients who have undergone knee, hip, or shoulder joint replacements; α-defensin or leukocyte esterase (LE strip) of synovial fluid was detected as the biomarker for PJI diagnosis; and Musculoskeletal Infection Society (MSIS) or utilizing a combination of clinical data was considered as the gold standard. Diagnostic parameters including sensitivity, specificity, diagnostic odds ratio (DOR), and area under the summary of receiver operating characteristics curve (AUSROC) were calculated for the included studies to evaluate the synovial fluid α-defensin and LE for PJI diagnosis. Results: After full-text review, 28 studies were qualified for this systematic review, 16 studies used α-defensin and the other 12 were conducted using LE strip. The pooled sensitivity, specificity, and DOR of LE strip were 87% (95% CI 84–90%), 96% (95% CI 95–97%), and 170.09 (95% CI 97.63–296.32), respectively, while the pooled sensitivity, specificity, and DOR of α-defensin were 87% (95% CI 83–90%), 97% (95% CI 96–98%), and 158.18 (95% CI 74.26–336.91), respectively. The AUSROC for LE strip and α-defensin were 0.9818 and 0.9685, respectively. Conclusion: Both LE strip and α-defensin of synovial fluid provide rapid and convenient diagnosis for PJI. Sensitivity of α-defensin and LE strip are the same, while both these two methods have high specificity in clinical practice. [ABSTRACT FROM AUTHOR]

Rheumatoid arthritis (RA), a chronic inflammatory disease, is characterized by cartilage damage, bone tissue destruction, morphological changes in synovial fluids, and synovial joint inflammation. The inflamed synovial tissue has potential for passive and active targeting because of enhanced permeability and retention effect and the existence of RA synovial macrophages and fibroblasts that selectively express surface receptors such as folate receptor β, CD44 and integrin αVβ. Although there are numerous interventions in RA treatment, they are not safe and effective. Therefore, it is important to develop new drug or drug delivery systems that specifically targets inflamed/swollen joints but attenuates other possible damages to healthy tissues. Recently some receptors such as toll-like receptors (TLRs), the nucleotide-binding oligomerization domain-like receptors, and Fc-γ receptor have been identified in synovial tissue and immune cells that are involved in induction or suppression of arthritis. Analysis of the TLR pathway has moreover suggested new insights into the pathogenesis of RA. In the present paper, we have reviewed drug delivery strategies based on receptor targeting with novel ligand-anchored carriers exploiting CD44, folate and integrin αVβ as well as TLRs expressed on synovial monocytes and macrophages and antigen presenting cells, for possible active targeting in RA. TLRs could not only open a new horizon for developing new drugs but also their antagonists or humanized monoclonal antibodies that block TLRS specially TLR4 and TLR9 signaling could be used as targeting agents to antigen presenting cells and dendritic cells. As a conclusion, common conventional receptors and multifunctional ligands that arte involved in targeting receptors or developing nanocarriers with appropriate ligands for TLRs can provide profoundly targeting drug delivery systems for the effective treatment of RA. [ABSTRACT FROM AUTHOR]

The transport and distribution of charged molecules in polyelectrolyte solutions are of both fundamental and practical importance. A practical example, which is the specific subject addressed in the present paper, is the transport and distribution of charged species into cartilage. The charged species could be a contrast agent or a drug molecule involved in diagnosis or treatment of the widespread degenerative disease osteoarthritis, which leads to degradation of articular cartilage. Associated scientific issues include the rate of transport and the equilibrium concentrations of the charged species in the cartilage and the synovial fluid. To address these questions, we present results from magnetic resonance micro-imaging experiments on a model system of articular cartilage. The experiments yield temporally and spatially resolved data on the transport of a negatively charged contrast agent (charge = -2), used in medical examinations of cartilage, into a polyelectrolyte solution, which is designed to capture the electrostatic interactions in cartilage. Also presented is a theoretical analysis of the transport where the relevant differential equations are solved using finite element techniques as well as treated with approximate analytical expressions. In the analysis, non-ideal effects are included in the treatment of the mobile species in the system. This is made possible by using results from previous Monte Carlo simulations. The results demonstrate the importance of taking non-idealities into account when data from measurements of transport of charged solutes in a system with fixed charges from biological polyelectrolytes are analyzed. [ABSTRACT FROM AUTHOR]

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Glucosamine (GlcN) is an amine sugar, in which a hydroxyl group of glucose is replaced with an amino group. It is an important part of the polysaccharides chitin and chitosan and is highly hydrophilic. It is also an important compound required for the formation of cartilage cells and represents one of the elementary units of the cartilage matrix and joint fluid. GlcN has been widely used in food, cosmetics, health care, and pharmaceutical industries. This paper fully addresses the categories and biomanufacturing methods of GlcN, including its production by fermentation with wild-type as well as engineered microorganisms and enzymatic catalysis with a series of chitinolytic enzymes. However, GlcN is usually produced from glucose by fermentation in a coupled manner with N-acetylglucosamine (GlcNAc). Enzymatic catalysis is thus a specific pathway for production of GlcN where chitin can be directly hydrolyzed to GlcN. In industry, GlcN produced with fungal mycelium as raw materials (plant GlcN) is thought as a high-end product because of vegetarian and non-transgenosis. In our opinion, more studies should be performed in order to develop a competitive enzymatic pathway using Aspergillus niger mycelium for the preparation of high-end GlcN. [ABSTRACT FROM AUTHOR]

We consider a system of nonlinear partial differential equations, modeling the motion of a viscous incompressible chemically reacting generalized Newtonian fluid in three space dimensions. The governing system consists of a steady convection-diffusion equation, for the concentration, and a generalized steady power-law-type fluid flow model, for the velocity and the pressure of the fluid, where the viscosity depends on both the shear-rate and the concentration through a concentration-dependent power-law index. The aim of the paper is to perform the mathematical analysis of a finite element approximation of this model. We consider a regularization of the model by introducing an additional term in the momentum equation and construct a finite element approximation of the regularized system. First, the convergence of the finite element method to a weak solution of the regularized model is shown, and we then prove that weak solutions of the regularized problem converge to a weak solution of the original problem. [ABSTRACT FROM AUTHOR]

In healthy joints, the cartilage surface coated with phospholipid multi-bilayers is governed by the lamellar-repulsive hydration mechanism. The phospholipid bilayers of biological surface are investigated by friction testing, while surface degradation is controlled by wettability. This paper proposes the presence of cartilage surfaces that are negatively charged results in highly efficient lubrication in natural joints. At pH ∼ 7.4, the mechanism of lamellar-repulsion between contacting cartilage surfaces is supported by charged macromolecules of synovial fluid and phospholipid lamellar phases. It was proven experimentally that phospholipid (PLs) bilayers with lamellar structure can act as an effective solid lubricant in friction and wear under biological test conditions. [ABSTRACT FROM AUTHOR]

Abstract The present paper represents Part II of the extensive study focused on the lubrication of hip joint replacements. The main goal is to assess the fundamentals of lubrication considering both hard-on-soft (Part I) and hard-on-hard (Part II) bearing pairs. In addition, the effect of individual constituents contained in the model fluid is clarified. For this purpose, multiple model fluids of various composition were employed. In this part of the study, metal-on-glass contact representing hard bearing pairs was observed in situ using pendulum hip joint simulator in combination with thin film colorimetric interferometry method. The designed test consists of initial static loading/unloading phase for the determination of adsorption of molecules on rubbing surfaces. This period is followed by swinging of the pendulum and latest static part under constant load. Three groups of measurements were carried out while fourteen different lubricants were tested. Initially, the experiments were performed with albumin-based model fluid. In that case a substantial positive effect of hyaluronic acid was identified. In contrast, the fluids with γ-globulin as a base constituent showed improved lubrication conditions when phospholipids were added to the solution. Finally, considering the complex fluid, a combined effect of hyaluronic acid and phospholipids caused a better endurance of the lubricant film. The latest part of the paper aims on the comparison of film formation considering hard and soft pairs, highlighting some clear differences. In general, hard pairs exhibit clear decreasing tendency of the film during swinging motion while opposite behaviour was observed for soft pairs. Highlights • In situ observation of lubricant film formation in hard-on-hard bearing pairs. • Combination of pendulum hip joint simulator and optical interferometry. • Investigation of various model fluids with various level of complexity. • Understanding of the role of albumin, γ-globulin, hyaluronic acid, and phospholipids. • Description of interaction of the constituents contained in synovial fluid. [ABSTRACT FROM AUTHOR]

Aims. The study aims were to verify the serum (S) and synovial fluid (SF) reference intervals (RIs) for human neutrophil defensins (HNP1-3); measure S and SF defensin concentrations in different types of SF, including non-inflammatory, inflammatory non-pyogenic, inflammatory pyogenic, and hemorrhagic; and to compare the HNP1-3 concentrations in SF and S with those of other inflammatory biomarkers. Methods. SF and S samples were collected from 92 patients. HNP1-3 concentrations were determined using enzyme-linked immunosorbent assays; glucose, lactate, interleukin-6, and procalcitonin using an automatic analyzer; and presepsin using a Pathfast system. There were 61 non-inflammatory, 11 inflammatory non-pyogenic, 11 inflammatory pyogenic, and 9 hemorrhagic SF. Non-inflammatory SF was divided into non-inflammatory normal and non-inflammatory osteoarthritis. The former was used to estimate the HNP1-3 RI in SF and S. Results. The estimated HNP1-3 RIs of SF and S were 12.47-437.42 mg/L and 5.45-44.75 µg/L, respectively. HNP1-3 differed significantly between S and SF and individual groups of SF (P

The elastic deformation of the human synovial joint in the standing and swing phases is presented in this paper, as well as the relationship between elastic muscle fibers and layer porosity using a mathematical model and analyzing the results with the appropriate boundary condition for the types of lubrication. During the gait cycle, elastic muscle fibers have a large impact on the magnetic field and the film (thinning of the thickness) of layers. The impact of elastic muscle fibers is to increase the hydrodynamic pressure and carry the load. We employed the double ZZ transformation as a strong tool to acquire a solution to the hydrodynamic pressure and bearing loads directly without finding the general solution of a differential equation. [ABSTRACT FROM AUTHOR]

The paper presents a series of aspects regarding the main biotribological phenomena occurring in the synovial joints. Although a great deal of research is carried out around the world about the biotribological processes in the human body's synovial joints, due to their complexity, they are not yet been fully understood and cannot establish a unique model of lubrication mechanism in these joints. The problem is complicated by the fact that in reality the cartilage is neither homogeneous nor isotropic and undergoes a large deformation during loading. According to several researchers, implantation and expulsion of synovial fluid in cartilage is not a simple phenomenon, although the boosted or weeping type of lubrication suggests this. The self‐generating lubrication mechanism postulated by Mow et al. (1987) takes into account the biphasic nature of cartilage and is based on the load‐dividing factor between the solid phase and the liquid. In recent years, studies have also been carried out to explore possible links between synovial joint lubrication mechanisms and degeneration processes. Tribological modeling is based on a number of parameters, such as: lubricant film thickness (or synovial fluid), maximum physiological load, articular cartilage surface roughness, friction coefficient, surface roughness, and lubrication regime. [ABSTRACT FROM AUTHOR]

The introduction of biologic disease modifying anti-rheumatic drugs (bMDARDs) have revolutionised the treatment of psoriatic arthritis (PsA). This combined with a ‘treat-to-target’ approach, means that achieving remission is increasingly possible. In patients with well-controlled PsA, there is little consensus on whether bDMARDs should be continued, tapered or discontinued altogether. Tapering or discontinuation of bDMARDs could offer significant financial savings and minimise patient burden and unwanted drug-related side effects. However, there is a risk of loss of remission. The primary focus of this paper is to review the current evidence on bDMARD tapering and discontinuation in PsA. We explore the criteria employed by studies to define patients eligible for bDMARD tapering or discontinuation and the process by which this occurs. We also review the outcomes of bDMARD tapering and discontinuation, the predictors, and the likelihood of restoring remission following relapse. To date, bDMARD tapering seems to be feasible and safe in patients with PsA who are in remission or with low disease activity. Lower disease activity prior to tapering seems to increase the likelihood of successful bDMARD tapering. In contrast, discontinuing bDMARDs appears to carry a substantial risk of loss of remission. Those with higher disease activity at time of tumour necrosis factor inhibitors discontinuation, current smokers, male sex, increased skin involvement, and synovial hypertrophy seen on ultrasound prior to discontinuation are at greater risk of losing remission post-bDMARD discontinuation. In those who lose remission, reinstating the standard dose of bDMARD appears to be effective in restoring remission. [ABSTRACT FROM AUTHOR]