There is interest in novel synovial fluid biomarkers for the detection of periprosthetic joint infection (PJI). Here, we assessed the diagnostic accuracy of 23 simple or sophisticated synovial fluid biomarkers for periprosthetic hip or knee infection detection. One hundred seven subjects were studied, 57 of whom had aseptic failure (AF) and 50 PJI. The following synovial fluid biomarkers were tested using spectrophotometric assays, immunoassays, lateral flow tests, or test strips: leukocyte count, monocyte percentage, lymphocyte percentage, neutrophil percentage, C‐reactive protein (CRP), glucose, lactate, granulocyte‐macrophage colony‐stimulating factor, interferon‐γ, interleukin‐1β (IL‐1β), IL‐2, IL‐4, IL‐5, IL‐6, IL‐8, IL‐10, IL‐12p70, IL‐13, IL‐17A, IL‐23, tumor necrosis factor‐α, α‐defensin, and leukocyte esterase. The best‐performing synovial fluid biomarkers to differentiate PJI from AF—that is, those with highest area under the curve compared to all other biomarkers—were leukocyte count, percent neutrophils and percent monocytes, CRP, and α‐defensin (P < .0001).

Cardiac surgery in the pediatric population is performed for a variety of reasons, including correction of congenital heart disease and acquired cardiac conditions. Pediatric cardiac surgery is not, however, without its risks, as post-operative complications have been seen in up to 43% of cases [1]. Among the risks is the development of acute kidney injury (AKI), a relatively common complication that can arise in the presence of multiple risk factors. Although AKI's exact mechanism, AKI's longterm outcomes, and treatment of AKI have yet to be fully illuminated, there have been advancements on these topics. Here, we describe the current understanding and practices as well as advances on the incidence, risk fac

Aims The aim of this study was to determine the diagnostic accuracy of α defensin (AD) lateral flow assay (LFA) and enzyme-linked immunosorbent assay (ELISA) tests for periprosthetic joint infection (PJI) in comparison to conventional synovial white blood cell (WBC) count and polymorphonuclear neutrophil percentage (PMN%) analysis. Methods Patients undergoing joint aspiration for evaluation of pain after total knee arthroplasty (TKA) or total hip arthroplasty (THA) were considered for inclusion. Synovial fluids from 99 patients (25 THA and 74 TKA) were analyzed by WBC count and PMN% analysis, AD LFA, and AD ELISA. WBC and PMN% cutoffs of ≥ 1,700 cells/mm3 and ≥ 65% for TKA and ≥ 3,000 cells/mm3 and ≥ 80% for THA were used, respectively. A panel of three physicians, all with expertise in orthopaedic infections and who were blinded to the results of AD tests, independently reviewed patient data to diagnose subjects as with or without PJI. Consensus PJI classification was used as the reference standard to evaluate test performances. Results were compared using McNemar’s test and area under the receiver operating characteristic curve (AUC) analysis. Results Expert consensus classified 18 arthroplasies as having failed due to PJI and 81 due to aseptic failure. Using these classifications, the calculated sensitivity and specificity of AD LFA was 83.3% (95% confidence interval (CI) 58.6 to 96.4) and 93.8% (95% CI 86.2 to 98.0), respectively. Sensitivity and specificity of AD ELISA was 83.3% (95% CI 58.6 to 96.4) and 96.3% (95% CI 89.6 to 99.2), respectively. There was no statistically significant difference between sensitivity (p = 1.000) or specificity (p = 0.157) of the two AD assays. AUC for AD LFA was 0.891. In comparison, AUC for synovial WBC count, PMN%, and the combination of the two values was 0.821 (sensitivity p = 1.000, specificity p < 0.001), 0.886 (sensitivity p = 0.317, specificity p = 0.011), and 0.926 (sensitivity p = 0.317, specificity p = 0.317), respectively. Conclusion The diagnostic accuracy of synovial AD for PJI diagnosis is comparable and not statistically superior to that of synovial WBC count plus PMN% combined. Cite this article: Bone Joint J 2021;103-B(6):1119–1126.

Over the past decade we have consistently shown that ketosis is neuroprotective against ischemic insults in rats. We reported that diet-induced ketotic rats had a significant reduction in infarct volume when subjected to middle cerebral artery occlusion (MCAO), and improved survival and recovery after cardiac arrest and resuscitation. The neuroprotective mechanisms of ketosis (via ketogenic diet; KG) include (i) ketones are alternate energy substrates that can restore energy balance when glucose metabolism is deficient and (ii) ketones modulate cell-signalling pathways that are cytoprotective. We investigated the effects of diet-induced ketosis following transient focal cerebral ischemia in mice. The correlation between levels of ketosis and hypoxic inducible factor-1alpha (HIF-1α), AKT (also known as protein kinase B or PKB) and 5' AMP-activated protein kinase (AMPK) were determined. Mice were fed with KG diet or standard lab-chow (STD) diet for 4 weeks. For the MCAO group, mice underwent 60 min of MCAO and total brain infarct volumes were evaluated 48 h after reperfusion. In a separate group of mice, brain tissue metabolites, levels of HIF-1α, phosphorylated AKT (pAKT), and AMPK were measured. After feeding a KG diet, levels of blood ketone bodies (beta-hydroxyburyrate, BHB) were increased. There was a proportional decrease in infarct volumes with increased blood BHB levels (KG vs STD; 4.2 ± 0.6 vs 7.8 ± 2.2 mm, mean ± SEM). A positive correlation was also observed with HIF-1α and pAKT relative to blood BHB levels. Our results showed that chronic ketosis can be induced in mice by KG diet and was neuroprotective against focal cerebral ischemia in a concentration dependent manner. Potential mechanisms include upregulation of cytoprotective pathways such as those associated with HIF-1α, pAKT and AMPK.

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