Validation and Accuracy of Synovial Alpha Defensin in a Suburban Academic Center after Implantation as Part of the Workup for Periprosthetic Joint infections

Introduction Periprosthetic joint infection (PJI) is a leading cause of total hip and knee arthroplasty failure. The Musculoskeletal Infection Society (MSIS) criteria for PJI has allowed diagnosis standardization. To increase the MSIS criteria accuracy, synovial fluid biomarkers have been tested. Studies evaluating synovial alpha defensin have reported both sensitivity and specificity up to 100%. In this study, we report our analysis on the use of alpha defensin testing in a suburban academic tertiary referral center. Methods We performed a retrospective analysis of a prospectively collected database of 133 patients tested for PJI over a 6 year period. From 2014, our standard infection evaluation protocol included synovial alpha defensin fluid analysis. Complete testing data was available on 128 patients. Both primary and revision total hip and knee arthroplasty were included. Sensitivity, specificity, positive predictive value (PPV) and negative predictive value (NPV) were calculated using the 2011 MSIS criteria. T-tests were performed for parametric data. Results Synovial testing of alpha defensin for PJI had a 95.00% sensitivity, a 91.67% specificity, a 67.86% PPV and a 99.00% NPV. Positive alpha defensin tests were corelated with positive serum and synovial CRP, synovial WBC count, and synovial polymorphonuclear cell percent. There was no correlation between positive synovial alpha defensin and age, sex, smoking or diabetic status. Conclusion Synovial testing for alpha defensin in an unbiased cohort gives high sensitivity and NPV comparable to published literature. We recommend using synovial alpha defensin testing for suspected PJI cases, as an additional data point to help determine likelihood

Factors Associated with Revision Surgery after Internal Fixation of Hip Fractures

Background: Femoral neck fractures are associated with high rates of revision surgery after management with internal fixation. Using data from the Fixation using Alternative Implants for the Treatment of Hip fractures (FAITH) trial evaluating methods of internal fixation in patients with femoral neck fractures, we investigated associations between baseline and surgical factors and the need for revision surgery to promote healing, relieve pain, treat infection or improve function over 24 months postsurgery. Additionally, we investigated factors associated with (1) hardware removal and (2) implant exchange from cancellous screws (CS) or sliding hip screw (SHS) to total hip arthroplasty, hemiarthroplasty, or another internal fixation device. Methods: We identified 15 potential factors a priori that may be associated with revision surgery, 7 with hardware removal, and 14 with implant exchange. We used multivariable Cox proportional hazards analyses in our investigation. Results: Factors associated with increased risk of revision surgery included: female sex, [hazard ratio (HR) 1.79, 95% confidence interval (CI) 1.25-2.50; P = 0.001], higher body mass index (fo

The sensitivity of estimates of multiphase fluid and solid properties of porous rocks to image processing

X-ray microcomputed tomography (X-ray μ-CT) is a rapidly advancing technology that has been successfully employed to study flow phenomena in porous media. It offers an alternative approach to core scale experiments for the estimation of traditional petrophysical properties such as porosity and single-phase flow permeability. It can also be used to investigate properties that control multiphase flow such as rock wettability or mineral topology. In most applications, analyses are performed on segmented images obtained employing a specific processing pipeline on the greyscale images. The workflow leading to a segmented image is not straightforward or unique and, for most of the properties of interest, a ground truth is not available. For this reason, it is crucial to understand how image processing choices control properties estimation. In this work, we assess the sensitivity of porosity, permeability, specific surface area, in situ contact angle measurements, fluid–fluid interfacial curvature measurements and mineral composition to processing choices. We compare the results obtained upon the employment of two processing pipelines: non-local means filtering followed by watershed segmentation; segmentation by a manually trained random forest classifier. Single-phase flow permeability, in situ contact angle measurements and mineral-to-pore total surface area are the most sensitive properties, as a result of the sensitivity to processing of the phase boundary identification task. Porosity, interfacial fluid–fluid curvature and specific mineral descriptors are robust to processing. The sensitivity of the property estimates increases with the complexity of its definition and its relationship to boundary shape

Fracture fixation in the operative management of hip fractures (FAITH): an international, multicentre, randomised controlled trial

Background Reoperation rates are high after surgery for hip fractures. We investigated the effect of a sliding hip screw versus cancellous screws on the risk of reoperation and other key outcomes. Methods For this international, multicentre, allocation concealed randomised controlled trial, we enrolled patients aged 50 years or older with a low-energy hip fracture requiring fracture fixation from 81 clinical centres in eight countries. Patients were assigned by minimisation with a centralised computer system to receive a single large-diameter screw with a side-plate (sliding hip screw) or the present standard of care, multiple small-diameter cancellous screws. Surgeons and patients were not blinded but the data analyst, while doing the analyses, remained blinded to treatment groups. The primary outcome was hip reoperation within 24 months after initial surgery to promote fracture healing, relieve pain, treat infection, or improve function. Analyses followed the intention-to-treat principle. This study was registered with ClinicalTrials.gov, number NCT00761813. Findings Between Mar