Synovial Fluid Leukocyte Count Research Articles

D-lactate is a promising biomarker for the diagnosis of periprosthetic joint infection.

Reliable biomarkers for the diagnosis of periprosthetic joint infection (PJI) are of paramount clinical value. To date, synovial fluid leukocyte count is the standard surrogate parameter indicating PJI. As D-lactate is almost solely produced by bacteria, it represents a promising molecule in the diagnostic workflow of PJI evaluation. Therefore, the purpose of this study was to assess the performance of synovial fluid D-lactate for diagnosing PJI of the hip and knee. These are preliminary results of a prospective multicenter study from one academic center. Seventy-two consecutive patients after total hip arthroplasty (THA) or total knee arthroplasty (TKA) were prospectively included. All patients received a joint aspiration in order to rule out or confirm PJI, which was diagnosed according to previously published institutional criteria. Synovial fluid D-lactate was determined spectrophotometrically at 450 nm. Receiver operating characteristic (ROC) analysis was performed to assess the diagnostic performance. Eighteen patients (25%) were diagnosed with PJI and 54 patients (75%) were classified as aseptic. Synovial fluid D-lactate showed a sensitivity of 90.7% (95% CI: 79.7%-96.9%) and specificity of 83.3% (95% CI: 58.6%-96.4%) at a cut-off of 0.04 mmol/L. The median concentration of D-lactate was significantly higher in patients with PJI than in those with aseptic conditions (0.048 mmol/L, range, 0.026-0.076 mmol/L vs. 0.024 mmol/L, range, 0.003-0.058 mmol/L, p < 0.0001). The predominat microogranisms were staphylococci, followed by streptococci and gram-negative bacteria. D-lactate bears a strong potential to act as a valuable biomarker for diagnosing PJI of the hip and knee. In our study, a cutoff of 0.04 mmol/L showed a comparable sensitivity to synovial fluid leukocyte count. However, its specificity was higher compared to conventional diagnostic tools. The additional advantages of D-lactate testing are requirement of low synovial fluid volume, short turnaround time and low cost.

IL-40: A New B Cell-Associated Cytokine Up-Regulated in Rheumatoid Arthritis Decreases Following the Rituximab Therapy and Correlates With Disease Activity, Autoantibodies, and NETosis.

BackgroundInterleukin 40 (IL-40) is a newly identified B cell-associated cytokine implicated in humoral immune responses and B cell homeostasis. As B cells play a pivotal role in autoimmunity, we investigated the function of IL-40 in rheumatoid arthritis (RA).MethodsIL-40 expression was determined in the synovial tissue from RA and osteoarthritis (OA) patients. IL-40 was analysed in the serum/synovial fluid of patients with RA (n=50), systemic lupus erythematosus (SLE, n=69), OA (n=44), and healthy controls (HC, n=50). We assessed the changes of IL-40 levels in RA patients following the B cell depletion by rituximab (n=29) or after the TNF inhibition by adalimumab (n=25). We examined the relationship between IL-40, disease activity, autoantibodies, cytokines, and NETosis markers. Effect of IL-40 on synovial fibroblasts was determined.ResultsIL-40 was overexpressed in RA synovial tissue, particularly by synovial lining and infiltrating immune cells. The levels of IL-40 were up-regulated in the synovial fluid of RA versus OA patients (p<0.0001). Similarly, IL-40 was increased in the serum of RA patients compared to HC, OA, or SLE (p<0.0001 for all) and decreased after 16 and 24 weeks (p<0.01 and p<0.01) following rituximab treatment. No significant effect of adalimumab on IL-40 was observed. IL-40 levels in RA patients correlated with rheumatoid factor-IgM and anti-cyclic citrullinated peptides (anti-CCP) in the serum (p<0.0001 and p<0.01), as well as in the synovial fluid (p<0.0001 and p<0.001). Synovial fluid IL-40 was also associated with disease activity score DAS28 (p<0.05), synovial fluid leukocyte count (p<0.01), neutrophil attractants IL-8 (p<0.01), MIP-1α (p<0.01), and markers of neutrophil extracellular traps externalization (NETosis) such as proteinase 3 (p<0.0001) and neutrophil elastase (p<0.0001). Synovial fibroblasts exposed to IL-40 increased the secretion of IL-8 (p<0.01), MCP-1 (p<0.05), and MMP-13 (p<0.01) compared to the unstimulated cells.ConclusionsWe show the up-regulation of IL-40 in RA and its decrease following B cell depleting therapy. The association of IL-40 with autoantibodies, chemokines, and markers of NETosis may imply its potential involvement in RA development. Moreover, IL-40 up-regulates the secretion of chemokines and MMP-13 in synovial fibroblasts, indicating its role in the regulation of inflammation and tissue destruction in RA.

The significance of synovial biopsy in the diagnostic workup of the low-grade periprosthetic joint infection of shoulder arthroplasty

IntroductionA common reason for painful shoulder arthroplasties and revision surgery is a low-grade periprosthetic joint infection (PJI). Diagnosing a low-grade infection is, however, a major diagnostic challenge. This applies even more to the shoulder, which differs from other large joints in terms of clinical features and microbiological spectrum. Aim of this study was to evaluate the diagnostic value of the synovial biopsy in the diagnostic workup of low-grade PJI of the shoulder.Materials and methodsA retrospective evaluation was conducted on 56 patients receiving revision surgery on their shoulder arthroplasty. A standardized preoperative workup was performed comprising CRP value, leukocyte blood count, synovial fluid microbiological analyses and leukocyte count from joint aspiration, and five synovial biopsy samples for bacteriologic and histologic analysis obtained through an arthroscopic approach. During revision surgery, five samples of periprosthetic tissue were harvested for bacteriologic and histologic analyses. The MSIS-Criteria 2014 were used to evaluate the diagnostic results.ResultsIn total, 15 of 56 revised prostheses turned out as PJI (27%). When applying our diagnostic workup, we obtained a sensitivity of 67% with a specificity of 95%. When performing a subgroup analysis on those patients that had received diagnostic biopsy, a sensitivity of 100% and a specificity of 83% could be achieved. With a sensitivity and specificity of 90% and 83%, respectively, the biopsy is the single method with the highest diagnostic value.ConclusionsThe sensitivity of only 67% of our standard workup emphasizes the difficulty to adequately diagnose low-grade infections after shoulder arthroplasty. The excellent specificity of 95% ensures, however, that non-infected prostheses are not incorrectly explanted. This study highlights that synovial biopsy has a high diagnostic value and should be done prior to complex revision surgeries to raise sensitivity in diagnosing a PJI.

Synovial Cell Count Before Reimplantation Can Predict the Outcome of Patients with Periprosthetic Knee Infections Undergoing Two-stage Exchange.

Although synovial fluid can be used to diagnose periprosthetic joint infections (PJI) effectively, only the cutoff values adopted at the time of PJI diagnosis have been standardized, and few data are currently available about effectiveness of synovial fluid examination before definitive reimplantation. We asked: (1) What are the most appropriate thresholds for synovial fluid leukocyte counts (WBC) and neutrophil percentage (PMN percentage) in a patient group undergoing definitive reimplantation after an uninterrupted course of antibiotic therapy for chronic PJI? (2) What is the predictive value of our synovial WBC and PMN percentage threshold compared with previously proposed thresholds? In all, 101 patients with PJI were evaluated for inclusion from January 2016 to December 2018. Nineteen percent (19 of 101) of patients were excluded because of the presence of a chronic inflammatory disease, acute/late hematogenous infection, low amount of synovial fluid for laboratory investigations or infection persistence after spacer placement, and adequate antibiotic therapy. Finally, 81% (82 of 101) of patients with a median (range) age of 74 years (48 to 92) undergoing two-stage revision for chronic TKA infection, who were followed up at our institution for a period 96 weeks or more, were included in this study. The patients did not discontinue antibiotic treatment before reimplantation and were treated for 15 days after reimplantation if intraoperative cultures were negative. No patient remained on suppressive treatment after reimplantation. Synovial fluid was aspirated aseptically with a knee spacer in place to evaluate the cell counts before reimplantation. Thirteen percent (11 of 82) of patients had persistent or recurrent infection, defined as continually elevated erythrocyte sedimentation rate or C-reactive protein levels coupled with local signs and symptoms or positive cultures. The synovial fluid WBC counts and PMN percentage from the 11 patients with persistent or recurrent PJI were compared with the 71 patients who were believed to be free of PJI. Receiver operating characteristic (ROC) curve analyses assessed the predictive value of the parameters, and the areas under the curves (AUCs) were evaluated. The sensitivities, specificities, and positive and negative predictive values were determined for the WBC count and PMN percentage. Patients with persistent or recurrent infection had higher median WBC counts (471 cells/µL versus 1344 cells/µL; p < 0.001) and PMN percentage (36% versus 61%; p < 0.001) than did patients believed to be free of PJI. ROC curve analysis identified the best threshold values to be a WBC count of 934 cells/µL or more (sensitivity 0.82 [95% CI 0.71 to 0.89], specificity 0.82 [95% CI 0.71 to 0.89]) as well as a PMN percentage of at least 52% (sensitivity 0.82 [95% CI 0.71 to 0.89] and specificity 0.78 [95% CI 0.67 to 0.86]. We found no difference between the AUCs for the WBC count and the PMN percentage (0.87 [95% CI 0.79 to 0.96] versus 0.84 [95% CI 0.73 to 0.95]. Comparing the sensitivities and specificities of the synovial fluid WBC count and PMN percentage proposed by other authors, we find that a PMN percentage more than 52% showed better predictive value than previously reported. Based on our findings, we believe that patients with WBC counts of at least 934 and PMN percentage of 52% or more should not undergo reimplantation but rather a repeat debridement, as their risk of persistent or recurrent PJI appears prohibitively high. The accuracy of the proposed cutoffs is better than previously reported. Level III, diagnostic study.

Optimal Synovial Fluid Leukocyte Count Cutoff for Diagnosing Native Joint Septic Arthritis After Antibiotics: A Receiver Operating Characteristic Analysis of Accuracy.

Urgent treatment of septic arthritis is key in preventing devastating morbidity or mortality. Accurate diagnosis is critical, and the standard diagnostic cutoff of 50,000 synovial leukocytes may be altered by previous administration of antibiotics. Our objective was to identify and compare a cutoff synovial leukocyte count with a high sensitivity and specificity for diagnosis of septic arthritis in patients who received antibiotics and those who had not. A receiver operating characteristic (ROC) curve was used to provide a discriminate cutoff value for diagnosing septic arthritis. A retrospective chart review of 383 patients was done over a 13-year period including those who had arthrocentesis of any joint. Two groups were created, those who had not been given antibiotics within 2 weeks (control) and those who received intravenous or oral antibiotics within 2 weeks before arthrocentesis. Relevant data included synovial leukocyte count and differential cell count. Additional metrics included temperature, erythrocyte sedimentation rate, and C-reactive protein. A ROC curve determined the optimal synovial white blood cell cutoff for diagnosing septic arthritis in native joints for each group. The ROC curve determined that patients who received antibiotics had an optimal cutoff of >16,000 cells (sensitivity = 82%, specificity = 76%), and a neutrophil percentage cutoff of >90% (sensitivity = 73%, specificity = 74%). The control group had an optimal synovial leukocyte cutoff of >33,000 cells (sensitivity = 96%, specificity = 95%). The optimal neutrophil percentage cutoff in the control group was >83% neutrophils (sensitivity = 89%, specificity = 79%). When a patient is given antibiotics before arthrocentesis, a diagnostic value of >16,000 synovial leukocytes should be used to guide treatment of septic arthritis. A diagnostic value of >33,000 synovial leukocytes yields the highest accuracy for diagnosis of septic arthritis in patients who have not been given antibiotics before arthrocentesis. III.

331. Septic arthritis: when is the joint clean enough?

BackgroundSeptic arthritis is an orthopedic emergency that requires debridement. Previous authors reported that patients with inflammatory arthropathy, diabetes, infection with S. aureus, involvement of a large joint, and synovial fluid WBC >85,000 are associated with >1 debridements. The purpose of this study was to determine factors associated with 1 vs >1 debridements.MethodsThis is a retrospective cohort of adult patients hospitalized at Denver Health Medical Center with large joint septic arthritis between 7/1/2012 and 4/13/20. Patients with implanted orthopedic material, osteomyelitis, and recurrent septic arthritis were excluded. Septic arthritis was defined as a patient presenting with acute arthritis and positive culture OR negative culture and no other etiology. Both electronic capture and manual chart review were performed. Descriptive statistics were used to characterize the population. Statistical analyses included bivariate and multivariate analyses.ResultsForty-four cases were included (26 knee [59.1%], 4 hip [9.1%], 6 elbow [13.6%], and 8 shoulder [18.2%]. The median age was 55.7 years (41.3–64.1], and 79.5% were male. The most common organisms were S. aureus (n=20, 45.5%) and beta-hemolytic Streptococcus (n=10, 22.7%). Three patients had no surgical debridement, 21 had 1 debridement, and 20 had >1 debridements.As compared to those who had 1 debridement, those with >1 debridements were more likely to be male (95% vs 61.9%, p=0.02) and to have a higher synovial fluid leukocyte count (102,761 vs 49,154, p=0.001), CRP at admission (162.5 vs 97.7, p=0.039), and WBC the day prior to debridement (13.4 vs 9.8, p=0.007). Intra-operative purulence trended to association with >1 debridements. Pre- to post-operative changes in opiate use, temperature, and ability to work with physical therapy were not associated with 1 vs >1 debridements. Both higher synovial fluid leukocyte counts and CRP value at admission were independently associated with >1 debridements (OR 2.31, p=0.015; OR 1.01, p=0.036 respectively).ConclusionPatients with higher synovial fluid leukocytes and CRP at admission were more likely to have >1 debridements. Additional studies with functional outcome scores are necessary to determine if >1 debridements are associated with better clinical outcomes.Disclosures All Authors: No reported disclosures

Thermogenic diagnosis of periprosthetic joint infection by microcalorimetry of synovial fluid

BackgroundSynovial fluid culture is the standard investigation for the preoperative diagnosis of periprosthetic joint infection (PJI). However, the culture has limited sensitivity and requires several days until result. We evaluated the value of isothermal microcalorimetry for real-time diagnosis of PJI based on heat produced by microbial growth in synovial fluid.MethodsPatients undergoing aspiration of prosthetic hip or knee joint before revision surgery were prospectively included between 2014 and 2015. The performance of microcalorimetry was compared to synovial fluid culture using McNemar’s chi-squared test. Pearson’s correlation coefficient was calculated for synovial fluid leukocyte count and microcalorimetric heat.ResultsOf 107 included patients (58 knee and 49 hip prosthesis), PJI was diagnosed in 46 patients (43%) and aseptic failure in 61 patients (57%) according to institutional criteria. In 26 PJI cases (56%) the pathogen grew in synovial fluid and intra-operative cultures. The sensitivity of synovial fluid culture and microcalorimetry was both 39% and the results were concordant in 98 patients (92%). In patients with PJI, microcalorimetry missed 4 pathogens which grew in synovial fluid culture, whereas culture missed 4 pathogens detected by microcalorimetry. A linear correlation (r = 0.366) was found between leukocyte count and microcalorimetric heat in synovial fluid (p < 0.001). The median time to positivity of microcalorimetry was 9 h (range, 1–64 h) vs. 3 days for cultures (range, 1–14 days).ConclusionMicrocalorimetry of synovial fluid allows thermogenic diagnosis of periprosthetic joint infection in synovial fluid. The diagnostic performance of synovial fluid microcalorimetry is comparable to culture and delivers results considerably faster.Trial registrationThis prospective study was registered on August 21, 2015 with the public clinical trial identification NCT02530229.

Synovial fluid leukocyte cell count before versus after administration of antibiotics in patients with septic arthritis of a native joint

BackgroundAntibiotics have been shown to affect the accuracy of cultures; so antibiotics are held prior to obtaining cultures intra-operatively. No study has evaluated the effects of antibiotics on synovial fluid leukocyte cell count. The purpose of the current study is to compare the leukocyte cell count of native joints with septic arthritis when antibiotics have been given before aspiration and when no antibiotics have been given prior to aspiration. MethodsThis study was performed at a community hospital and a level 1 urban trauma hospital after IRB approval from both institutions from July 2007 to July 2017. Inclusion criteria comprised of a diagnosis of septic arthritis with positive cultures and a recorded arthrocentesis with cell count performed. Patients with septic arthritis were identified using ICD-9 codes 711.00–711.99 and ICD-10 codes M00 – M02. A retrospective chart review was performed and data was collected. Patients were placed into one of two groups. Group 1 received no antibiotics for two weeks prior to arthrocentesis, group 2 received antibiotics within 24 h prior to arthrocentesis. Demographic information, cell count number and differential, and blood lab values were collected. Timing data was also collected on timing of admission, antibiotics, joint irrigation, and discharge from the inpatient setting. ResultsThere were 81 patients meeting final inclusion criteria. The average cell count for the group which received antibiotics (n = 30) was 40,408 ± 29,433 while the average cell count for the group receiving no antibiotics (n = 51) was 93,824 ± 73,875 (p < .0001). The average length of stay was not significantly different between the antibiotic group versus no antibiotic group (14.0 days vs 12.1 days p = .4). The time from admission to arthrocentesis and admission to washout was longer for the antibiotic group versus no antibiotic group (p = .004 and p = .002, respectively). ConclusionWhen antibiotics are given prior to arthrocentesis of a septic joint, there is an associated lower synovial fluid leukocyte count compared to when no antibiotics are given prior. Level of evidenceLevel III.

Prosthetic joint infection

There is no uniformly accepted definition for prosthetic joint infection. The presentation is often varied, and the classical features of infection, such as fever, leukocytosis, and other typical signs of sepsis, are often absent. A prosthesis is a foreign body, and its presence alone is a risk factor for infection. Also, the microorganism load that will produce an established infection in a prosthetic joint is often less compared to a native joint.The strongest factor that defines prosthetic joint infection is perhaps the recovery of a microorganism from a joint aspirate or surgically obtained peri-prosthetic material. Other factors that support prosthetic joint infection include the presence of a sinus tract communicating with the joint space, wound dehiscence, purulence around the joint without an alternative explanation, loosening of the prosthesis, elevated synovial fluid leukocyte count with neutrophil predominance, and elevated inflammatory markers. However, failure to identify a pathogen does not rule out infection.

Clinical-like cryotherapy improves footprint patterns and reduces synovial inflammation in a rat model of post-traumatic knee osteoarthritis

Cryotherapy is a non-pharmacological treatment commonly used to control inflammation and improve function after acute traumas. However, there are no definitive findings about its effects on chronic joint diseases such as knee osteoarthritis (KOA). The aim of this study was to investigate the effects of clinical-like cryotherapy on functional impairment and synovial inflammation in a rat model of KOA generated by anterior cruciate ligament transection (ACLT). Thirty-two male Wistar rats were randomly divided into four groups (n = 8/group): Control, KOA, KOA + Cryotherapy and KOA + Placebo. The last two groups were submitted to the relevant interventions twice a day for five days (61 to 65), with each session lasting 20 min. Gait test, skin temperature, thermal response threshold and joint swelling were assessed in all groups before ACLT surgery, and pre (60th day) and post (66th day) intervention protocols. On day 66, the animals were euthanized and exsanguinated to remove the synovial membrane for histopathological examination and synovial fluid to determine the leukocyte count and cytokine concentration. After the intervention period (66th day), footprint area only increased in the KOA + Cryotherapy group (P = 0.004; 14%) when compared to KOA and KOA + Placebo, but did not differ from controls. Cryotherapy lowered the synovial fluid leukocyte count (P < 0.0001; ≥95.0%) and cytokine concentration (P < 0.0001; ≥55%) when compared to the KOA and Placebo groups. Synovial score and synovial fibrosis did not differ in the KOA groups. In conclusion, footprint patterns improved in rats with ACLT-induced KOA as a result of clinical-like cryotherapy, which also lowered the synovial fluid leukocyte count and inflammatory cytokine concentration in these rats.

Clinical usefulness of automated cellular analysis of synovial fluids: a paradigmatic case report for diagnosing peri-prosthetic infections

We describe here the case of an 18 years old male patient who underwent osteosynthesis surgery with a plate and screws for multi-fragment fracture of his right femur, in December 2000. The patient developed a series of complications up to May 2017, when he was readmitted with severe functional impairment and inability to walk without crutches. Physical examination revealed erythema, swelling at surgical site and leakage of pus from sinus-tract. An arthrocentesis was hence performed, followed by white blood cell count and differential in synovial fluid with Sysmex XN 2000 body fluid mode. The final leukocyte count was 38×10 9 /L, with 95% polymorphonuclear leukocytes (PMN), thus compatible with peri-prosthetic infection. The patient underwent additional surgery to remove the knee replacement, accurate debridement and antibiotic impregnated static cement spacer implantation. Three months after surgery, the patient was readmitted for removing the spacer, replaced by a new static device. In May 2018, surgical debridement and removal of the spacer was scheduled with resection arthroplasty. In November 2018 the patient presented again a sinus tract, and underwent another arthrocentesis for physical and microbiological examination of synovial fluid. The leukocyte count in the synovial fluid was again performed with Sysmex XN 2000 body fluid mode, and revealed the presence of 44.5×10 9 /L cells, with 90% PMN. The synovial fluid was positive for Van-A Enterococcus faecalis , so that right hip disarticulation was urgently planned. In conclusions, this case provides clear evidence that automated leukocyte count and differential in synovial fluid shall now be considered an unavoidable part of the diagnostic approach to patients with suspected peri-prosthetic infections.

Performance of synovial fluid D-lactate for the diagnosis of periprosthetic joint infection: A prospective observational study

ObjectivesSynovial fluid leukocyte count is the current standard test for diagnosing periprosthetic joint infection (PJI). As D-lactate is almost exclusively produced by bacteria, it represents a useful biomarker for bacterial infection. We evaluated the performance of synovial fluid D-lactate for the diagnosis of PJI and compared it with the synovial fluid leukocyte count. MethodsConsecutive patients with joint aspiration of a prosthetic hip, knee or shoulder joint were prospectively included. PJI was diagnosed according to the working criteria of the European Bone and Joint Infection Society (EBJIS). The synovial fluid D-lactate was determined spectrophotometrically at 570 nm, synovial fluid leukocytes were counted by flow cytometry. The receiver operating characteristic (ROC) analysis was performed to assess the diagnostic performance of investigated parameters. ResultsOf 148 patients, 44 (30%) were diagnosed with PJI and 104 (70%) with aseptic failure. For diagnosis of PJI, the sensitivity of synovial fluid D-lactate (at cut-off 1.263 mmol/l) was 86.4% [95% CI, 75.0–95.5%] and the specificity was 80.8% [95% CI, 73.1–88.5%]. The AUCs of D-lactate concentration and leukocyte count were 90.3% [95% CI 85.7–95.0%] and 91.0% [95% CI 85.1–96.8%], respectively (p = 0.8). Virulence of the pathogen did not influence the D-lactate concentration (p = 0.123). The synovial fluid erythrocyte concentration correlated with D-lactate in patients with aseptic failure (ρ = 0.339, p <0.01). ConclusionSynovial fluid D-lactate showed similar performance to the leukocyte count for diagnosis of PJI. Advantages of D-lactate test are requirement of low synovial fluid volume, short turnaround time and low cost.

Post-arthroscopic septic arthritis of the knee. Analysis of the outcome after treatment in a case series and systematic literature review.

The aim of this study was to review the characteristics of patients with septic arthritis after ACL reconstruction comparing our results with those deriving from the literature review. Patients with suspected post arthroscopic septic arthritis of the knee occurring within 6 months after surgery were evaluated to be included in the investigation. Septic arthritis was defined by i) clinical evidence; ii) laboratory investigations; iii) synovial fluid leukocyte count of more than 2,5 x 104/μL or positive cultures obtained by synovial fluid aspirate. Thirty-nine patients (median age 25 years, range 17-42) with septic arthritis following ACL reconstruction were enrolled. Staphylococci were the main bacteria identified. Resolution within 4 weeks of local signs was observed more frequently in those receiving arthroscopic debridement and synovectomy coupled with antibiotic therapy (18/21 vs. 9/18, p<0.05). Fever was present in 33 (85%) cases. Fever disappearance and CRP normalization within 4 weeks were reported more frequently in patients receiving intravenous antibiotics (17/20 vs. 9/19, p<0.05). Similar findings were retrieved by literature analysis. An intravenous antibiotic therapy with surgical debridement is the first-line treatment for septic arthritis. Staphylococci are the main causative agents, justifying an empiric therapeutic approach with an anti-MRSA agent and cephalosporin.

Is CD163 - A Marker of Progression in Osteoarthritis?

Background: CD163 is a cell surface glycoprotein as known as a hemoglobin/haptoglobin scavenger receptor. The Soluble form of CD163 attenuates macrophages immune response. Objectives: The aim of this study is to describe the effect of CD 163 phagocytes on progression and joint destruction by osteoarthritis (OA). Methods: Twenty OA patients participated in this study. The mean age of patients was 68 ± 8 years (range 46 to 75 years) and the male to female le ratio was 1.5, with 10.6 ± 6.3 years mean duration of OA disease. Twenty synovial biopsies of OA patients and 10 healthy control (HC) specimens were analyzed for CD163 expression (using the immunohistochemistry method) with soluble CD163 (using the ELISA method) in synovial fluid (SF) as well as sCD163 in the serum of. Results: The score of CD163 expression in the synovial intima (P < 0.01), the subintima (P < 0.01) and periarticular area (P < 0.02) increased in OA as compared with the healthy control group. Synovial fluid sCD163 and serum sCD163 levels increased in the OA sample population as compared with the healthy control group. Also, Synovial fluid and serum sCD163 positively associated with ESR and CRP (P < 0.02, P < 0.01and P < 0.06, P < 0.06 respectively). The mean concentration of SF sCD163 was about 2 times higher than in serum in OA patients (P < 0.01). There was no correlation between clinical findings of patients and SF leukocyte count the (P < 0.09). Conclusions: This study shows increased numbers of CD163 macrophages with an enhanced phagocytes infiltration within the degenerated synovium as well as the local production of serum and SF sCD163. Therefore, these cells could provide a future therapeutic strategy for osteoarthritis.

Multiplex Polymerase Chain Reaction and Microcalorimetry in Synovial Fluid: Can Pathogen-based Detection Assays Improve the Diagnosis of Septic Arthritis?

To prospectively evaluate automated multiplex PCR and isothermal microcalorimetry tests for rapid and accurate diagnosis of septic arthritis. Patients with acute arthritis were prospectively included from October 2014 to September 2015. In synovial fluid (SF), leukocyte count and differential, culture, PCR, and microcalorimetry were determined. Septic arthritis was diagnosed by positive SF culture or (1) local clinical signs and symptoms, (2) increased SF leukocyte count, and (3) exclusion of noninfectious causes of inflammatory arthropathy. The performance of individual tests was compared with McNemar's test. Among 57 patients, 22 (39%) were diagnosed with septic arthritis. SF culture grew a pathogen in 10 patients (46%), PCR was positive in 5 (23%), and microcalorimetry in 10 (46%). Compared to SF culture, 49 concordant pairs were found for both methods (PCR and microcalorimetry; 86% agreement). In SF, PCR failed to detect Staphylococcus aureus (2 patients), Streptococcus pneumoniae (1 patient), Streptococcus dysgalactiae (1 patient), and Clostridium clostridioforme (1 patient). Microcalorimetry failed to detect S. dysgalactiae (1 patient), Streptococcus agalactiae (1 patient), and C. clostridioforme (1 patient). No statistical differences between the performance of SF culture, and PCR and microcalorimetry, respectively, were found. The processing time for PCR was 5 h and for microcalorimetry a median of 8.8 h (range, 2.3-64 h), whereas cultures required a median of 4.5 days (range, 3-14 days). Performance of SF PCR was inferior while microcalorimetry was similar to culture but provided results considerably faster. [Clinical trial registration number (https://www.clinicaltrials.gov): NCT02530229].

Alpha defensin, leukocyte esterase, C-reactive protein, and leukocyte count in synovial fluid for pre-operative diagnosis of periprosthetic infection.

Synovial fluid analysis for diagnosis of prosthetic joint infections has gained increasing interest in the recent past when markers more specific for these infections than the serum ones have been identified. Despite the important steps forward, identification of a gold standard has not yet been identified. In this study, usefulness of alpha defensin, leukocyte esterase, C-reactive protein (CRP), and white blood cells (WBCs) in synovial fluids alone and in combination for diagnosis of prosthetic joint infection was evaluated. Synovial fluids from 32 infected and 34 not infected patients were analyzed. Sensitivity, specificity, positive and negative predictive values, diagnostic accuracy, and receiver-operating characteristic (ROC) curves were calculated for each parameter. Moreover, combination of coupled variables was also evaluated by logistic regression analysis. Sensitivity of alpha defensin, CRP, leukocyte count, and leukocyte esterase were 84.4%, 87.5%, 93.7%, and 93.8%, respectively. Specificity was 91.2% for leukocyte counts, 94.1% for alpha defensin, 97.0% for CRP, and 97.1% for leukocyte esterase. Diagnostic accuracy was 89.4% for alpha defensin, 92.4% for WBC counts and CRP, and 95.5% for leukocyte esterase. No statistical differences were observed in area under the curve (AUC) of the ROC curves of alpha defensin, CRP, and leukocyte counts. Logistic regression analysis applied to a model comprising all the variables showed an AUC higher than AUC of coupled variables. In conclusion, results of this study confirm the high sensitivity and specificity of synovial leukocyte esterase for diagnosis of prosthetic joint infection, also suggesting the need to assess a panel of markers to optimize diagnosis of these infections.

Diagnostic accuracy of synovial fluid, blood markers, and microbiological testing in chronic knee prosthetic infections.

This retrospective study was undertaken to define cut-off values for synovial fluid (SF) leukocyte count and neutrophil percentage for differentiating aseptic failure and periprosthetic joint infection (PJI) and to evaluate the diagnostic accuracy of blood inflammatory markers, and microbiological testing according to the criteria proposed by the International Consensus Meeting (ICM) of Philadelphia. All patients who underwent revision total knee arthroplasty from January 2010 to July 2015 were included: we identified and classified 31 PJIs and 136 aseptic joints. The diagnostic performance of single test was assessed by receiver operating characteristic curve analyses. The sensitivity and specificity were calculated for each of the cut-off values and the area under the curve (AUC) was calculated. The median SF leukocyte count as well as the neutrophil percentage and inflammatory markers were significantly higher in patients with PJI than in those with aseptic failure (p<0.001). A leukocyte count of>2.8×103/μL had a sensitivity of 83.8% and a specificity of 89.7% whereas a neutrophil percentage of>72% yielded a marginally higher sensitivity of 84% and a specificity of 91%. Applying the ICM criteria we found a significant correlation between all these diagnostic measures and PJI (p<0.001) except for a single positive culture. The most accurate criterion of the ICM was the synovial neutrophil differential (AUC=0.89; 95% CI 0.81-0.97), followed by SF leukocyte count (AUC=0.86; 95% CI 0.78-0.94), increased inflammatory markers (AUC=0.85; 95% CI 0.76-0.93), and two positive periprosthetic cultures (AUC=0.84; 95% CI 0.73-0.94). The presence of sinus tract communicating with the joint and a single positive culture showed unfavourable diagnostic accuracy (AUC=0.60, 95% CI 0.47-0.72; AUC=0.49, 95% CI 0.38-0.61, respectively) CONCLUSIONS: The present study highlights the adequate ability of fluid cell count and neutrophil differential to distinguish between PJI and aseptic loosening. The clinical utility of fluid analysis in diagnosing infection can be improved by evaluation of other diagnostic criteria. Level I Diagnostic Study.

Pentosan Polysulfate as a Disease Modifier of Cartilage Degeneration in Experimental Osteoarthritis

Reasons for performing study: Disease modifying drugs for Osteoarthritis (OA) is an important trend of development of an appropriate therapeutic protocol for both human and animal. To date no ideal OA treatment protocol has been described. Objectives: To assess clinical, histologic, and biochemical effects of sodium pentosan polysulfate (NaPPS) administered intramuscullary (IM) for treatment of experimentally induced osteoarthritis in donkeys. Study design: OA was induced using repeated injection of allogenous donkey cartilage. Six donkeys received NaPPS (3 mg/kg, IM) on study days 70, 77, 84, and 91. Six control donkeys received the same volume of saline (0.9% w/v NaCl) IM on study days 70, 77, 84, and 91. Clinical, gross, histologic, histochemical, and biochemical findings as well as synovial fluid analysis were evaluated. Methods of testing hypotheses: Lameness score, carpal circumference, joint flexion angle, Synovial fluid analysis, light and scanning electron microscopy were evaluated. Results: Induction of osteoarthritis caused increase in the lameness score, joint circumference, synovial fluid calcium, phosphorus, magnesium, total protein and leukocyte count and cartilage damage. NaPPS treatment significantly reduced synovial fluid Ca, Mg, P and cartilage damage. Conclusions: NaPPS resulted in significant improvement in clinical signs and articular cartilage healing, and no adverse effects were detected confirming that NaPPS has disease-modifying properties. Potential relevance: NaPPS is a suitable therapeutic option for osteoarthritis in equines.

Animal model of acute gout reproduces the inflammatory and ultrasonographic joint changes of human gout.

IntroductionGout is an inflammatory condition induced by the deposition of monosodium urate (MSU) crystals in the joints and soft tissues that can produce acute or chronic arthritis. Several animal models of crystal-induced inflammation have been proposed that involve direct injection of MSU-crystals into different anatomical structures; however, only a few of these models reflect a true diarthrodial joint microenvironment in which an acute gouty attack takes place. The aim of this study was to assess the inflammatory and structural joint changes in a rabbit model of acute gout attack by ultrasound (US), synovial fluid (SF) and histopathological analyses.MethodsUnder US guidance, 42 rabbit knees were randomly injected with a suspension of 50 mg/ml of either MSU or allopurinol synthetic crystals. The control group received intra-articular vehicle of phosphate-buffered saline (PBS). US evaluation, SF and histopathological analyses were performed at days 1, 3, and 7.ResultsA total of 21 rabbit knees were assigned to the control group, 12 to the MSU-crystals group, and 9 to the allopurinol crystals group. By US, the MSU crystals group displayed the double contour sign and bright stippled aggregates in 67% and 75% of joints, respectively. Neither control knees nor allopurinol crystals group displayed these US signs. Power Doppler (PD) signal was moderate to intense in the MSU-crystals group and greater than both the allopurinol crystal and control groups at day 1 (P <0.001) and 3 (P <0.05), with its practical disappearance by day 7. SF leukocyte count was 40,312 ± 6,369 cells/mm3 in the MSU-crystals group, higher than in controls (P = 0.004) and allopurinol crystal group (P = 0.006). At day 7, SF leukocyte count decreased in both MSU and allopurinol crystal groups reaching the non-inflammatory range. Histologically, at day 3 intense synovial polymorphonuclear cells infiltration and MSU aggregates were identified.ConclusionThe rabbit model of MSU crystal-induced acute arthritis efficiently reproduces the inflammatory, US, SF and histopathological changes of the human acute gouty attack.Electronic supplementary materialThe online version of this article (doi:10.1186/s13075-015-0550-4) contains supplementary material, which is available to authorized users.

Preliminary results of a new test for rapid diagnosis of septic arthritis with use of leukocyte esterase and glucose reagent strips.

Most currently used tools to diagnose septic arthritis are either not readily available or fail to provide real-time results. Reagent strip tests have identified infections in various body fluids. We hypothesized that combined leukocyte esterase and glucose strip tests can aid in diagnosing septic arthritis in native synovial fluid because (1) leukocyte esterase concentrations would be elevated at the infection site because of secretion by recruited neutrophils, and (2) glucose concentrations would be reduced because of bacterial metabolism. We prospectively investigated synovial fluid from consecutive patients with an atraumatic joint effusion who underwent arthrocentesis in our emergency department during a one-year period. Leukocyte esterase and glucose strip tests were performed on the synovial fluid. Synovial fluid leukocyte count, crystal analysis, Gram staining, culture, and glucose concentration results were also assessed. Nineteen fluids were classified as septic and 127 as aseptic. Considering septic arthritis to be present when the leukocyte esterase reading was positive (++ or +++) and the glucose reading was negative (-) yielded a sensitivity of 89.5% (95% confidence interval [CI], 66.9% to 98.7%), specificity of 99.2% (95% CI, 95.7% to 99.9%), positive predictive value of 94.4% (95% CI, 72.7% to 99.9%), negative predictive value of 98.4% (95% CI, 94.5% to 99.8%), positive likelihood ratio of 114, and negative likelihood ratio of 0.11. The synovial leukocyte counts and polymorphonuclear cell percentages were consistent with the semiquantitative readings on the leukocyte esterase strip tests, and the glucose concentrations were consistent with the glucose strip test results. Combined leukocyte esterase and glucose strip tests can be a useful additional tool to help confirm or rule out a diagnosis of septic arthritis.