Determination of vancomycin and meropenem in serum and synovial fluid of patients with prosthetic joint infections using UPLC-MS/MS.

Numerous studies have suggested that intra-articular administration of antibiotics following primary revision surgery may be one of the methods for treating prosthetic joint infection (PJI). Vancomycin and meropenem are the two most commonly used antibiotics for local application. Determining the concentrations of vancomycin and meropenem in the serum and synovial fluid of patients with PJI plays a significant role in further optimizing local medication schemes and effectively eradicating biofilm infections. This study aimed to establish a rapid, sensitive, and accurate ultra-performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS) method for determining the concentrations of vancomycin and meropenem in human serum and synovial fluid. Serum samples were processed using acetonitrile precipitation of proteins and dichloromethane extraction, while synovial fluid samples were diluted before analysis. Chromatographic separation was achieved in 6 min on a Waters Acquity UPLC BEH C18 column, with the mobile phase consisting of 0.1% formic acid in water (solvent A) and acetonitrile (solvent B). Quantification was carried out using a Waters XEVO TQD triple quadrupole mass spectrometer with an electrospray ionization (ESI) source in positive ion mode. The multiple reaction monitoring (MRM) mode was employed to detect the following quantifier ion transitions: 717.95-99.97 (norvancomycin), 725.90-100.04 (vancomycin), 384.16-67.99 (meropenem). The method validation conformed to the guidelines of the FDA and the Chinese Pharmacopoeia. The method demonstrated good linearity within the range of 0.5-50 µg/ml for serum and 0.5-100 µg/ml for synovial fluid. Selectivity, intra-day and inter-day precision and accuracy, extraction recovery, matrix effect, and stability validation results all met the required standards. This method has been successfully applied in the pharmacokinetic/pharmacodynamic (PK/PD) studies of patients with PJI.

An update on the study of synovial fluid in the geriatric patient.

BACKGROUND: The characteristics of synovial fluid (SF) in geriatric patients differ from those in younger patients. In Mexico, epidemiologic data on the incidence of different rheumatic diseases in geriatric patients are scarce. OBJECTIVE: To describe the physical characteristics of geriatric SF and the prevalence of crystals in knee and other joint aspirates from patients with previously diagnosed joint disease. MATERIALS AND METHODS: A retrospective study was performed with a baseline of 517 SF samples between 2011 and 2023. White blood cell count was performed by Neubauer chamber and crystals were identified by polarized light microscopy. Descriptive statistical analysis was performed and prevalence was reported as a percentage. RESULTS: The mean age of the adults was 73.5±5.0 years, 54.4% were women and 45.6% were men. The mean SF volume was 6.3±9.5mL in older adults and 15.3±24.9mL in those younger than 65 years. The mean viscosity in older adults was 9.5±4.5mm and the mean leukocyte count was 7352±16,402leukocytes/mm3. Seventy percent of the older adults' SFs were referred to the laboratory for osteoarthritis (OA), with lower proportions for rheumatoid arthritis (RA) (14.6%) and gout (5.1%). Of the crystals observed in the geriatric population, 14.6% corresponded to monosodium urate crystals (CUM) and 18.9% to calcium pyrophosphate crystals (CPP). CONCLUSIONS: The characteristics of LS in older adults were smaller volume, increased viscosity, and non-inflammatory. The main diagnoses were OA, RA, and gout. The crystal content of the SF of the geriatric population corresponded mainly to CPP.

Advancing the Diagnosis of Periprosthetic Joint Infections: Integrated Microfluidic Platform for Alpha-Defensins-Specific Aptamer Selection and Its Analytical Applications.

Periprosthetic joint infections (PJIs) pose a significant challenge in orthopedic surgery, particularly total joint arthroplasty (TJA), due to the potential for implant failure and increased patient morbidity. Early and accurate detection of PJIs is crucial for timely intervention and better patient prognosis. Herein, we successfully screened a high-affinity aptamer targeting alpha-defensin complex human neutrophil protein 1-3 (HNP 1-3; potential PJI biomarkers in synovial fluid [SF]) for the first time using systematic evolution of ligands by exponential enrichment (SELEX) on an integrated microfluidic platform. The compact microfluidic device enabled efficient screening, with each round completed within <2 h, comprising five rounds of positive selection, two rounds of negative selection, and one round of competitive selection. A novel one-aptamer-one-antibody assay was further developed from the optimal aptamer screened, and it could accurately quantify HNP 1-3 in SF within 3 h with only ∼50 µL of SF. The assay demonstrated strong binding affinity and specificity for the target protein in SF. Thirteen PJI SF samples were accurately diagnosed and the assay was accurate over a wide dynamic range (0.32-100 mg/L). This study has showcased a rapid and accurate diagnostic tool for PJI detection, which should see widespread use in the clinic, holding promise for potential analytical applications in orthopedic surgery and improving patient care.

Analysis of the Level of Adiponectin and Selected Cytokines in Patients with Knee Osteoarthritis.

Background and Objectives: Knee osteoarthritis (KOA) is a degenerative disease that is continuously targeting people of different ages, but especially the elderly population, the number of which tends to increase continuously at the global level. Apart from age, excess weight can influence the evolution of the disease, with obesity being associated with a weak inflammation stage and an imbalance between pro-inflammatory and anti-inflammatory cytokines. The present work aimed to analyze specific biomarkers, namely ACRP-30, IL-10, TNF-α, and IL-6, in knee synovial fluid, and correlate them with KOA patients' clinical data, radiographic changes, and functional and pain scores. Materials and Methods: 24 subjects with KOA and over 50 years of age participate in the present study. Synovial fluid was harvested using ultrasound guidance from the target knees of the enrolled KOA patients, and the levels of ACRP-30, IL-10, TNF-α, and IL-6 were measured using enzyme-linked immunosorbent assays (ELISA). All patients underwent a supine X-ray at the target knee and were classified using Kellgren-Lawrence (K-L) grading. The Western Ontario and McMaster University Osteoarthritis Index (WOMAC) was used to assess self-reported physical function, pain, and stiffness. Results: The obtained results highlighted a significant correlation between age and adiponectin level (p = 0.0451, r = -0.412). Also, the IL-10 values are lower in cases where the intensity of the pain is more pronounced (p = 0.0405, r = -0.421). In addition, analyzing the data by gender, it was observed that in the case of males, stiffness is more related to age (p = 0.0079, r = 0.7993), compared to women (p = 0.0203, r = 0.6223). In the case of women, the progression of the disease tends to increase more intensively the WOMAC score's total values (p = 0.00031, r = 0.8342), compared with men (p = 0.0289, r = 7013). Regarding interleukins and BMI, significant correlations were observed only in the case of men. Conclusions: A significant correlation between age and adiponectin, and adiponectin and IL-6, suggests that advanced age may contribute to adiponectin reduction. Comparing men with women, it was observed that men's age is more related to rigidity, and IL-6 and IL-10 are directly correlated to BMI; in addition, women seem to be more sensitive to pain and stiffness.

Performance of adenosine deaminase in synovial fluid for the diagnosis of tuberculous arthritis: A systematic review and meta-analysis.

OBJECTIVES: Adenosine deaminase (ADA) activity has shown good performance in diagnosing pleural, peritoneal, and meningeal tuberculosis. This meta-analysis aimed to evaluate the performance of measuring ADA activity in synovial fluid for the early diagnosis of joint tuberculosis. METHODS: We searched published information in MEDLINE, Embase, Cochrane Library, Web of Science, and MedRxiv databases, as well as unpublished information in the American College of Rheumatology and European League Against Rheumatism for conference abstracts (2012-2021). We also scanned the reference lists of articles. Two reviewers independently applied the criteria for selection, assessed quality, and extracted data (PROSPERO number CRD42021284472). RESULTS: Seven independent studies (N=305 subjects) that compared ADA activity in synovial fluid with a composite reference diagnostic method for tuberculosis were included. Overall, the risk of bias was judged low. Studies were classified as high quality (n=3; 148 subjects) and low quality (n=4; 157 subjects). Pooled sensitivity and specificity of ADA activity was 94% (95% confidence interval [CI], 0.89-98; I2=23%) and 88% (95% CI, 83-92; I2=83%), respectively. The random-effects model for pooled diagnostic Odds ratio was 67.1 (95%CI, 20.3-222.2; I2=30%). The receiver operating characteristic curve area was 0.96 (95% CI, 0.92-0.99). Meta-regression did not identify the quality of the study, country of publication, or the type of assay as a source of heterogeneity. CONCLUSIONS: Measuring ADA activity in synovial fluid demonstrates good performance for the early diagnosis of joint tuberculosis.

Endoplasmic reticulum stress-related protein GRP78 and CHOP levels in synovial fluid correlate with disease progression of primary knee osteoarthritis: A cross-sectional study.

BACKGROUND: Endoplasmic reticulum (ER) stress has been shown to play an important role in osteoarthritis (OA). OBJECTIVE: This study was aimed at assessing the relationship of endoplasmic reticulum (ER) stress-related glucose-regulated protein 78 (GRP78) and CCAAT/enhancer-binding protein homologous protein (CHOP) concentrations in the serum/synovial fluid (SF) with disease severity of primary knee osteoarthritis (pkOA). METHODS: Patients with pkOA together with healthy individuals were consecutively recruited from our hospital. The levels of GRP78 and CHOP in serum / SF were detected using enzyme-linked immunosorbent assay. The levels of IL-6 and MMP-3 were also examined. Radiographic progression of pkOA was evaluated based on Kellgren-Lawrence (K-L) grades. Receiver Operating Characteristic (ROC) curves were used to assess the diagnostic value of GRP78/CHOP levels with regard to K-L grades. The assessment of clinical severity was conducted using the visual analogue scale (VAS), Oxford knee score (OKS), and Lequesne algofunctional index (LAI). RESULTS: A total of 140 pkOA patients and 140 healthy individuals were included. Serum GRP78 and CHOP levels in pkOA patients were not significantly different from those in healthy individuals. The SF GRP78 and CHOP levels in healthy controls were not detected due to ethical reasons. Compared to those with K-L grade 2 and 3, the pkOA patients with K-L grade 4 had higher GRP78 and CHOP levels in the SF with statistical significance. In addition, the pkOA patients with K-L grade 3 exhibited drastically upregulated GRP78 and CHOP concentrations in the SF compared to those with K-L grade 2. Positive correlations of GRP78 and CHOP levels with K-L grades, IL-6, and MMP-3 levels in the SF were observed. ROC curve analysis indicated that both GRP78 and CHOP levels may act as decent indicators with regard to OA. GRP78 and CHOP concentrations in the SF were positively correlated with VAS/LAI score and negatively associated with OKS score. CONCLUSION: The study indicated that GRP78 and CHOP levels in the SF but not the serum were positively correlated with disease severity of pkOA.

Lactic Acid-Induced Colloidal Microrheology of Synovial Fluids.

The presence of colloidal scaffolds composed of proteins and hyaluronic acid engenders unique viscous and elastic properties to the synovial fluid (SF). While the elastic resistance of SF due to the presence of such nanoscale structures provides the load-bearing capacity, the viscous nature enables fluidity of the joints during the movements to minimize the wear and tear of the adjacent muscle, cartilage, or bone tissues. It is well-known that the hypoxic conditions at the bone joints often increase the lactic acid (LA) concentration due to the occurrence of excess anaerobic respiration during either hyperactivity or arthritic conditions. The present study uncovers that in such a scenario, beyond a critical loading of LA, the colloidal nanoscaffolds of SF break down to precipitate higher molecular weight (MW) proteins and hyaluronic acid (HA). Subsequently, the viscosity and elasticity of SF reduce drastically to manifest a fluid that has reduced load bearing and wear and tear resistance capacity. Interestingly, the study also suggests that a heathy SF is a viscoelastic fluid with a mild Hookean elasticity and non-Newtonian fluidity, which eventually transforms into a viscous watery liquid in the presence of a higher loading of LA. We employ this knowledge to biosynthesize an artificial SF that emulates the characteristics of the real one. Remarkably, the spatiotemporal microscopic images uncover that even for the artificial SF, a dynamic cross-linking of the high MW proteins and HA takes place before precipitating out of the same from the artificial SF matrix, emulating the real one. Control experiments suggest that this phenomenon is absent in the case when LA is mixed with either pure HA or proteins. The experiments unfold the specific role of LA in the destruction of colloidal nanoscaffolds of synovia, which is an extremely important requirement for the biosynthesis and translation of artificial synovial fluid.

Calcium ions have a detrimental impact on the boundary lubrication property of hyaluronic acid and lubricin (PRG-4) both alone and in combination.

Cartilage demineralisation in Osteoarthritis (OA) patients can elevate calcium ion levels in synovial fluid, as evidenced by the prevalence of precipitated calcium phosphate crystals in OA synovial fluid. Although it has been reported that there is a potential connection between elevated concentrations of calcium ions and a deterioration in the lubrication and wear resistance of cartilage tissues, the mechanism behind the strong link between calcium ion concentration and decreased lubrication performance is unclear. In this work, the AFM friction, imaging, and normal force distance measurements were used to investigate the lubrication performances of hyaluronic acid (HA), Lubricin (LUB), and HA-LUB complex in the presence of calcium ions (5 mM, 15 mM, and 30 mM), to understand the possible mechanism behind the change of lubrication property. The results of AFM friction measurements suggest that introducing calcium ions to the environment effectively eliminated the lubrication ability of HA and HA-LUB, especially with relatively low loading applied. The AFM images indicate that it is unlikely that structural or morphological changes in the surface-bound layer upon calcium ions addition are primarily responsible for the friction results demonstrated. Further, the poor correlation between the effect of calcium ions on the adhesion forces and its impact on friction suggests that the decrease in the lubricating ability of both layers is likely a result of changes in the hydration of the HA-LUB surface bound layers than changes in intermolecular or intramolecular binding. This work provides the first experimental evidence lending towards the relationship between bone demineralisation and articular cartilage degradation at the onset of OA and the mechanism through which elevated calcium levels in the synovial fluid act on joint lubrication.

Diagnostic Test Performances for Identifying Periprosthetic Joint Infection in Hip Hemiarthroplasty.

INTRODUCTION: Periprosthetic joint infection (PJI) is a devastating complication of hip hemiarthroplasty (HHA) that is not well-represented in the literature. Therefore, this study aimed to evaluate diagnostic markers for identifying PJI in patients after HHA and compare them with the most recent 2018 International Consensus Meeting on Musculoskeletal Infection criteria. METHODS: A total of 98 patients (64 PJIs, 65.3%) were analyzed. Patients were identified by relevant Current Procedural Terminology and International Classification of Diseases-9/10 codes from 2000 to 2021 across a single healthcare system. Preoperative or intraoperative synovial fluid nucleated cell (NC) count, synovial polymorphonuclear (PMN) percentage, serum erythrocyte sedimentation rate (ESR), serum C-reactive protein (CRP), and serum white blood cell count were compared with Student t -test between aseptic and septic cohorts. Diagnostic utility and laboratory cutoff values were determined using receiver-operating characteristic curves and Youden index, respectively. RESULTS: Mean values were significantly higher in the septic cohort for synovial NC count (120,992.2 versus 1,498.0 cells/µL, P < 0.001), synovial PMN percentage (91.3% versus 56.2%, P < 0.001), serum ESR (75.6 versus 36.3 mm/hr, P < 0.001), serum CRP (20.2 versus 125.8 mg/L, P < 0.001), and serum white blood cell count (8.5 versus 11.5 cells/µL, P < 0.001). Synovial NC count, synovial PMN percentage, and serum CRP had excellent PJI discriminatory ability with an area under the curve of 0.99, 0.90, and 0.93, respectively. Optimal cutoffs were 2,700 cells/µL for synovial NC count (100% sensitivity and 94% specificity), 81.0% for synovial PMN percentage (96% sensitivity and 89% specificity), 52.0 mm/hr for serum ESR (75% sensitivity and 80% specificity), and 40.0 mg/L for serum CRP (85% sensitivity and 92% specificity). CONCLUSION: Our findings support the continued use of routine serum and synovial fluid tests for diagnosing PJI in HHA patients. Optimal cutoff values for both synovial fluid biomarkers were very close in alignment with the 2018 International Consensus Meeting criteria. LEVEL OF EVIDENCE: Level III, retrospective comparative study.

Two-dimensional liquid chromatography measurement of meropenem concentration in synovial fluid of patients with periprosthetic joint infection.

Periprosthetic joint infection (PJI) is a catastrophic complication following joint replacement surgery. One potential treatment approach for PJI could be the combination of one-stage revision and intra-articular infusion of antibiotics. Meropenem is one of the commonly used intra-articular antibiotics in our institution. Determining the concentration of meropenem in the joint cavity could be crucial for optimizing its local application, effectively eradicating biofilm infection, and improving PJI treatment outcomes. In this study, we developed a simple, precise, and accurate method of two-dimensional liquid chromatography (2D-LC) for determining the concentration of meropenem in human synovial fluid. The method was then validated based on the guidelines of the Food and Drug Administration and the Chinese Pharmacopoeia. Meropenem showed good linearity in the range of 0.31-25.01 µg/mL (r ≥ .999). Selectivity, intra-day and inter-day precision and accuracy, extraction recovery, and stability validation results were all within the acceptance range. This method has been successfully applied to the determination of synovial fluid samples from PJI patients, providing a useful detection method for meropenem therapeutic drug monitoring (TDM) in PJI patients.

Knee Osteotomy Decreases Joint Inflammation Based on Synovial Histology and Synovial Fluid Analysis.

PURPOSE: To examine the biological changes in the joints of patients with knee osteoarthritis (OA) before and after around-knee osteotomy (AKO), focusing on synovial fluid (SF) and synovial pathological changes. METHODS: Patients who underwent AKO for medial compartment knee OA between 2019 and 2021 were examined. SF and synovium were obtained at the time of AKO and plate removal after bone union (mean, 16.8 months [range: 11-38 months] postoperatively). SF volume and interleukin (IL)-6 concentrations in SF were assayed using enzyme-linked immunosorbent assay. Synovitis was assessed histologically using a semiquantitative scoring system. Macrophage infiltration was assessed by immunohistochemistry using a semiquantitative score for F4/80 expression. The M1/M2 ratio was calculated using percentage of cells positive for CD80 and CD163. The expression of proinflammatory cytokines was assessed by the percentage of IL-1ß- and IL-6-positive cells. The number of vascular endothelial growth factor-positive luminal structures was counted to assess angiogenesis. The change in each parameter was compared before and after AKO using the Wilcoxon matched-pairs signed-rank test. RESULTS: Twenty-four knees of 21 patients were included. SF volume and IL-6 concentration significantly decreased postoperatively (12.6 ± 2.1 mL vs 4.2 ± 0.6 mL; P < .0001 and 50.5 ± 8.6 pg/mL vs 20.7 ± 3.8 pg/mL; P = .0001, respectively). A significant reduction in synovitis score (P = .0001), macrophage infiltration (P < .0003), M1/M2 ratio (P < .0007), angiogenesis (P < .0001), and the percentage of IL-1ß- and IL-6-positive cells in the intima (P < .008 and P < .002, respectively) was found after AKO. CONCLUSIONS: SF volume and IL-6 concentrations in the SF decreased and inflammatory synovium pathology improved after AKO. In addition to biomechanical changes, the biological environment of the joint can be improved after AKO. LEVEL OF EVIDENCE: Level IV, retrospective therapeutic case series.

Neutrophil-Lymphocyte Ratio and Lymphocyte-Monocyte Ratio correlate with Chronic Prosthetic Joint Infection but are not useful markers for diagnosis.

PURPOSE: To investigate reported correlations between Neutrophil-to-Lymphocyte (NLR) and Lymphocyte-to-Monocyte (LMR) ratios and their value in diagnosis of chronic prosthetic joint infection (PJI) in a large cohort of patients from a single specialist hospital. METHODS: Diagnostic aspirations of 362 patients under investigation for PJI were identified. Of the included patients 185 patients received a final diagnosis of PJI and 177 were classed as aseptic. Established criteria (ICM 2018) were employed to define PJI. Included in the analysis are differential white cell counts, C-Reactive Protein (CRP), Synovial Leukocyte Count, Synovial Alpha-defensin ELISA and Synovial Leukocyte esterase activity. Receiver-operator characteristic (ROC) curves were calculated for each of the available diagnostic tests together with the corresponding area under the curve values (AUC). Youden's index was utilized to identify the optimal diagnostic threshold point for the NLR and LMR. Other diagnostic tests were evaluated as per the threshold values previously defined in the literature and specified in the ICM criteria. RESULTS: Using Youden's Index to identify the optimal NLR cut-off within our cohort we established a value of 2.93. This yielded a sensitivity of 0.60 and specificity of 0.64. The area under the curve (AUC) of a receiving operator characteristics (ROC) curve was 0.625. Regarding the LMR the results demonstrate similar findings; a positive correlation with a diagnosis of infection but poor sensitivity and specificity. The AUC for LMR was 0.633 and was not superior to NLR (P = 0.753). CONCLUSIONS: There is a significant correlation between higher Neutrophil-Lymphocyte and Lymphocyte-Monocyte ratios, and a diagnosis of PJI. The sensitivity and specificity of this calculation is poor and the does not add value to the diagnostic algorithm for PJI. LEVEL OF EVIDENCE: Level III Retrospective Cohort analysis.

Neutrophil Extracellular Trap-related Biomarkers Are Increased in the Synovial Fluid of Patients With Periprosthetic Joint Infections.

BACKGROUND: The diagnosis of periprosthetic joint infection (PJI) is a major challenge in clinical practice. The role of neutrophils in fighting infection has been increasingly understood, and one mechanism of action of these cells is neutrophil extracellular traps. However, little is known about this process in PJI. QUESTIONS/PURPOSES: (1) Are the biomarkers of neutrophil extracellular trap formation (citrullinated histone H3 [H3Cit], cell-free DNA [cf-DNA], and myeloperoxidase [MPO]) increased in the synovial fluid of patients with PJI? (2) What is the diagnostic accuracy of biomarkers of neutrophil extracellular trap formation for PJI? METHODS: Between May 2020 and March 2021, 43 patients who underwent revision THA or TKA were enrolled in this study. Eleven patients were excluded and 32 patients were categorized into the PJI group (n = 16) or non-PJI group (n = 16) according to the 2018 Second International Consensus Meeting on Musculoskeletal Infection criteria. There were 15 men and 17 women in this study, with a median (range) age of 70 years (60 to 80 years). Twenty-seven patients had TKA and five had THA. We measured cf-DNA, MPO, and H3Cit in synovial fluid. The sensitivity, specificity, and receiver operating characteristic curve were calculated for each biomarker using the Musculoskeletal Infection Society criteria as the gold standard for diagnosis and considering a clinical surveillance of 2 years for patients in the non-PJI group. RESULTS: Patients with PJI had higher levels of synovial fluid cf-DNA (median [range] 130 ng/µL [18 to 179] versus 2 ng/µL [0 to 6]; p < 0.001), MPO (1436 ng/µL [55 to 3996] versus 0 ng/µL [0 to 393]; p < 0.001), and H3Cit (2115 ng/µL [5 to 2885] versus 3 ng/µL [0 to 87]; p < 0.001) than those in the non-PJI group. In receiver operating characteristic curve analyses, we observed near-perfect performance for all biomarkers evaluated, with an area under the curve of 1 (95% CI 0.9 to 1), 0.98 (95% CI 0.9 to 1), and 0.94 (95% CI 0.8 to 0.99) for cf-DNA, MPO, and H3Cit, respectively. The sensitivity for detecting PJI using synovial fluid was 100% for cf-DNA, 94% for MPO, and 88% for H3Cit. The specificity was 100% for cf-DNA and MPO, and 88% for H3Cit. CONCLUSION: Our results show that neutrophils in the periprosthetic microenvironment release neutrophil extracellular traps as part of the bactericidal arsenal to fight infection. These results allow a better understanding of the cellular and molecular processes that occur in this microenvironment, enabling the design of more assertive strategies for identifying new biomarkers and improving the available ones. Novel studies are needed to define whether and how neutrophil extracellular trap-related biomarkers can be useful for diagnosing PJI. LEVEL OF EVIDENCE: Level II, diagnostic study.

Morphine concentrations in distal thoracic limb synovial fluid following intravenous regional limb perfusion in horses.

Twelve adult horses were randomly assigned to 2 groups in a prospective experimental trial. A pneumatic tourniquet (425 mmHg) was placed, under sedation, proximal to the carpus on one randomly chosen thoracic limb. A cephalic vein catheter was placed distal to the tourniquet to establish an intravenous regional limb perfusion technique (IVRLP) with morphine (0.1 mg/kg) diluted with saline 0.9% to 0.1 mL/kg, and the tourniquet left in place for 30 minutes. Horses were euthanized at 1 h (Group I) or 6 h (Group II) following the IVRLP and synovial fluid from the radiocarpal, intercarpal, metacarpophalangeal, distal interphalangeal, and digital flexor tendon sheath was obtained from the injected and contralateral (control) limb immediately after. Morphine concentrations were determined using liquid chromatography-mass spectrometry. An unpaired t-test was used to compare morphine concentrations from both groups (P < 0.05). Synovial morphine concentrations were detected in the injected limb in all horses in Group I, except in one horse in the radiocarpal joint, and detected in 5 of 6 horses in Group II. Mean synovial concentrations ranged between 301.8 ± 192.3 and 608 ± 446.6 ng/mL in Group I and between 27.0 ± 17.7 and 136.8 ± 103.6 ng/mL in Group II and were significantly higher in Group I between paired anatomical sites of both groups for the radiocarpal and distal interphalangeal joints, and the digital flexor tendon sheath. In conclusion, concentrations of morphine after IVRLP can be detected in synovial fluid distal to the tourniquet at 1 and 6 hours in horses.

Douze chevaux adultes ont été assignés au hasard à deux groupes dans un essai expérimental prospectif. Un garrot pneumatique (425 mmHg) a été placé, sous sédation, à proximité du carpe sur un membre thoracique choisi au hasard. Un cathéter de la veine céphalique a été placé en aval du garrot pour établir une technique de perfusion intraveineuse régionale des membres (IVRLP) avec de la morphine (0,1 mg/kg) diluée avec une solution saline de 0,9 % à 0,1 mL/kg, et le garrot a été laissé en place pendant 30 minutes. Les chevaux ont été euthanasiés 1 h (groupe I) ou 6 h (groupe II) après l'IVRLP et le liquide articulaire de la gaine radiocarpienne, intercarpienne, métacarpo-phalangienne, interphalangienne distale et du tendon fléchisseur digital a été obtenu à partir du membre injecté et controlatéral (témoin) juste après. Les concentrations de morphine ont été déterminées par chromatographie liquide-spectrométrie de masse. Un test de t non apparié a été utilisé pour comparer les concentrations de morphine des deux groupes (P < 0,05). Des concentrations de morphine synoviale ont été détectées dans le membre injecté chez tous les chevaux du groupe I, sauf chez un cheval dans l'articulation radiocarpienne et détectées chez 5 des 6 chevaux du groupe II. Les concentrations synoviales moyennes variaient entre 301,8 ± 192,3 et 608 ± 446,6 ng/mL dans le groupe I et entre 27,0 ± 17,7 et 136,8 ± 103,6 ng/mL dans le groupe II et étaient significativement plus élevées dans le groupe I entre les sites anatomiques appariés des deux groupes pour le radiocarpien et les articulations interphalangiennes distales, et la gaine du tendon fléchisseur numérique. En conclusion, les concentrations de morphine après IVRLP peuvent être détectées dans le liquide synovial en aval du garrot à 1 et 6 heures chez les chevaux.(Traduit par Docteur Serge Messier).

The Diagnostic Utility of Fast Tests for Detecting C-Reactive Protein in Synovial Fluid in Periprosthetic Joint Infections.

BACKGROUND: Despite the fact that many synovial fluid biomarkers have found application in the routine diagnosis of periprosthetic joint infection (PJI), this process still remains a challenge for orthopaedic surgeons. To simplify this process, fast point-of-care (POC) tests can be used during ambulatory visits and in operating room conditions. However, before such tests can be routinely used in clinical practice, they require validation. The purpose of the present study was to evaluate the diagnostic accuracy of different fast POC tests for detecting C-reactive protein (CRP) in synovial fluid for the diagnosis of PJI. METHODS: Synovial fluid samples were collected from 120 consecutive patients who underwent revision total joint arthroplasty (TJA). The patients were divided into 2 groups. The first group included 76 patients who underwent revision for reasons other than infection (the aseptic revision TJA [arTJA] group), and the second group included 44 patients who underwent revision because of periprosthetic joint infection (PJI). The diagnosis of infection was made according to the International Consensus Meeting (ICM) 2018 criteria. All patients were operatively treated at a single orthopaedic center from January 2022 to February 2023. Four fast CRP tests with different cutoff values (1 and 3 mg/L, ≥8 mg/L, ≥10 mg/L [cassette], ≥10 mg/L [strip]) were used off-label for synovial fluid testing. Tests were performed on the same synovial fluid samples, and the results of these tests were compared with those obtained with the laboratory method. RESULTS: The cassette test with a minimum cutoff value of ≥8 mg/L demonstrated the best accuracy for the diagnosis of chronic PJI, with a sensitivity and specificity of 90.9% and 90.8%, respectively. For the cassette test with a cutoff value of >3 mg/L, the sensitivity and specificity were 68.2% and 77.6%, respectively. For the tests with a minimum cutoff value of ≥10 mg/L, the sensitivity and specificity were 77.3% and 94.7%, respectively, for the cassette test and 77.3% and 96.1%, respectively, for the strip test. The laboratory method with the statistically calculated threshold (2.7 mg/L) revealed the highest AUC (area under the receiver operating characteristic curve) value (0.95), with 90.9% sensitivity and 94.7% specificity. CONCLUSIONS: The cassette POC test with the minimum cutoff value of ≥8 mg/L had very good accuracy for the diagnosis of chronic PJI. This test had comparable sensitivity and slightly lower specificity in comparison with the laboratory method with the calculated threshold of 2.7 mg/L. LEVEL OF EVIDENCE: Diagnostic Level III . See Instructions for Authors for a complete description of levels of evidence.

Longitudinal evaluation of fentanyl concentrations in equine plasma and synovial fluid following application of transdermal fentanyl patches over one carpal joint.

OBJECTIVE: To determine if transdermally delivered fentanyl can achieve greater concentrations of fentanyl in synovial fluid when applied over a synovial structure. STUDY DESIGN: Randomized, experimental study. ANIMALS: Six healthy adult horses. METHODS: Each horse had two 100 µg/h fentanyl matrix patches applied on the dorsal aspect of one, randomly assigned, carpometacarpal joint (CMCJ) for 48 h. Whole blood and bilateral synovial samples from the intercarpal joint were obtained at 0, 2, 6, 12, 24, 36 and 48 h. Fentanyl concentrations were measured with liquid chromatography-mass spectrometry. RESULTS: All subjects achieved detectable concentrations of fentanyl in both plasma and synovial fluid. Time to peak synovial and plasma concentration was 12 h. At 6 h, the synovial concentration in the untreated carpus (0.104 ng/mL ± 0.106) was lower than plasma fentanyl concentrations 0.31 ± 0.27 (p = .036). At 12 h, both treated (0.55 ng/mL ± 0.3) and untreated (0.53 ng/mL ± 0.28) synovial fluid fentanyl concentrations were lower than plasma (0.87 ng/mL ± 0.48) concentrations (p < .001 and p = .001, respectively). Synovial concentrations of fentanyl did not differ between treated and untreated joints (p > 0.608 for all time points). CONCLUSION: Application of fentanyl matrix patches directly over the CMCJ did not result in increased fentanyl concentrations in the synovial fluid of the treated intercarpal joint in normal horses. CLINICAL SIGNIFICANCE: There is likely no analgesic advantage to placing fentanyl patches directly over the affected joint, as it did not result in increased synovial concentrations at the tested site.

Leukocyte esterase and alpha-defensin in periprosthetic joint infection: predictive quality and correlation in a prospective study.

PURPOSE: Periprosthetic joint infection (PJI) is a rare but serious complication of total joint arthroplasty (TJA). An accurate diagnosis of PJI preoperatively does not exist. Alpha-defensin (AD) is a proven and common indicator. The diagnostic marker of leukocyte esterase (LE) promises some advantages: feasibility, availability, and fast result reporting. The aim of this study was the evaluation of the predictive quality and correlation between both diagnostic tools in the diagnosis of PJI. METHODS: A prospective study was conducted between April 2018 and August 2022. All patients with suspicion of PJI on hip and knee joint were included and underwent a routine and standardized joint punction. For laboratory diagnostics of AD, the synovial liquid was analyzed by ELISA. The sample was additionally applied to a LE test strip (Combur 10 Test, Roche Diagnostics, Mannheim, Germany). RESULTS: A total of 249 patients were examined (mean age 67.12 ± 11.89; gender distribution man/woman 139 (55.8%)/110(44.2%), hip/knee 71(28.5%)/178 (71.5%). According to EBJIS criteria, PJI was diagnosed in 54 (21.7%) patients. AD showed excellent results with an AUC of 0.930 (sensitivity/specificity 0.870/0.990). LE yielded very good results with an AUC of 0.820 (sensitivity/specificity 0.722/0.918). Both parameters showed a strong positive correlation. CONCLUSION: LE is a rapidly available alternative in PJI diagnostics. The simultaneous determination of both markers may enhance diagnostic reliability. A routine usage may shorten the time from diagnosis to treatment of PJI.

Arthrocentesis and soft tissue aspiration and injection.

Accessing a joint with a needle (arthrocentesis) to extract synovial fluid is a skill intrinsic to the rheumatologist's praxis. Joint aspirations are essential for diagnosing or excluding septic joints, are the gold standard for diagnosing acute crystal arthritis, and can provide valuable information about the nature of other forms of arthritis. In appropriate settings, injecting medications into joints can provide rapid, temporary, or even prolonged relief of pain and swelling and can provide a window of relief until other treatment modalities (anti-inflammatories, immunomodulators, and physical therapy) can enforce durable responses. Soft tissue aspirations (e.g., of bursae) and soft tissue injections (of bursae, tendons, trigger points, and areas of nerve compression) can provide similar relief, earning the practitioner the gratitude of the patient. Here, we provide a primary on joint and soft tissue aspiration and injection, including indications for and against procedures, preparing for procedures, and approaches to specific musculoskeletal structures.

Synovial fluid analysis: Relevance for daily clinical practice.

Synovial fluid analysis can provide a prompt and definite diagnosis of crystal-induced arthritis, the most common acute inflammatory arthritis and a cause of chronic arthritis that may mimic rheumatoid, psoriatic, or peripheral spondyloarthritis. In many patients the diagnosis of gout or calcium pyrophosphate arthritis cannot be made with certainty without synovial fluid analysis. Additional information from fluid analysis can assist the clinician in honing the differential diagnosis of non-crystalline arthritis.