Several options to standardize the definition of periprosthetic joint infection (PJI) have been created including the 2013 Musculoskeletal Infection Society (MSIS), 2018 Intentional Consensus Meeting (ICM), and the 2019 proposed European Bone and Joint Infection Society (EBJIS) criteria. Synovial fluid biomarkers have been investigated in an effort to simplify and improve the diagnosis of PJI. The aim of this study was to test the sensitivity, specificity, positive, and negative predicted values (PPV and NPV, respectively) of a calprotectin point of care (POC) test for diagnosing PJI in revision total knee arthroplasty (TKA) patients comparing different sets of criteria (2013 MSIS, 2018 ICM, and 2019 EBJIS criteria) used to define patients as with or without infection. From October 2018 to January 2020 and under IRB approval 123 intraoperative samples of synovial fluid were prospectively collected at two academic hospitals in the same institution from revision TKA patients. All patients underwent standard clinical and laboratory evaluation for PJI at our institution, allowing for categorization using the 3 criteria. Patients were adjudicated by 2 blinded and independent reviewers for the 3 sets of criteria. The 3 criteria agreed 91.8% of the time. Four likely cases by the 2019 proposed EBJIS were considered unlikely and 1 inconclusive case by the 2018 ICM was considered not infected for the purposes of analysis. Calprotectin POC testing followed manufacturer's instructions using a threshold of >50 mg/L to indicate PJI. Sensitivities, specificities, PPV, NPV, and areas under the curve (AUC) were calculated for the 3 sets of criteria.Aim
Method
It is unclear if the prevalence of resistance organisms causing (PJI) in total hip/knee arthroplasty is different among North/South American and European countries. Therefore, we sought to compare causative organisms, rates of resistant organisms, and polymicrobial infections in hospitals in North/South America, and Europe. We performed a retrospective study of 654 periprosthetic hip (n=361) and knee (n=293) infections (January 2006-October 2019) identified at two facilities in the United States (US) (n=159), and single institutions located in Argentina (n=99), Uruguay (n=130), United Kingdom (UK) (n=103), Germany (n=59), and Russia (n=104). The analyses were performed for the entire cohort, knees, and hips. Alpha was set at 0.05.Aim
Method
Despite several synovial fluid biomarkers for diagnosis of periprosthetic joint infection (PJI) have being investigated, point-of-care (POC) tests using these biomarkers are not widely available. Synovial calprotectin has recently been reported to effectively exclude diagnosis of PJI and a novel lateral flow POC test using it has shown potential to be effective. Thus, the aims of this study were to 1) validate calprotectin POC with enzyme linked immunosorbet assay (ELISA) 2) at 2 separate thresholds for PJI diagnosis in total knee arthroplasty (TKA) patients using the 2013 Musculoskeletal Infection Society (MSIS) PJI diagnosis criteria as the gold standard. Intraoperative synovial fluid samples were prospectively collected from 123 patients who underwent revision TKAs (rTKA) at two academic hospitals within the same healthcare system from October 2018 to January 2020. The study was conducted under IRB approval. Included patients followed the hospital standard for their PJI diagnostic work-up. Data collection included demographic, clinical, and laboratory data in compliance with MSIS criteria. Synovial fluid samples were analysed by calprotectin POC and ELISA tests in accordance with manufacturer's instructions. Patients were categorized as septic or aseptic using MSIS criteria by two independent reviewers blinded to calprotectin assay results. The calprotectin POC and ELISA test performance characteristics were calculated with sensitivities, specificities, positive, and negative predicted values (PPV and NPV, respectively) and areas under the curve (AUC) for 2 different PJI diagnosis scenarios: (1) a threshold of >50 mg/L and (2) a threshold of >14 mg/L.Aim
Method
Varying degrees of posterior glenoid bone loss occurs in patients with end stage osteoarthritis and can result in increased glenoid retroversion. The excessive retroversion can affect implant stability, eccentric glenoid loading, and fixation stresses. Ultimately, the goal is to correct retroversion to restore normal biomechanics of the glenohumeral joint. The objective of this study was to identify the optimal augmented glenoid design based on finite element analysis (FEA) modeling which will provide key insights into implant loosening mechanisms and stability. Two different augmented glenoid designs, posterior wedge and posterior step- were created as a computer model by a computer aided design software (CAD). These implant CAD models were created per precise manufacturers dimensions and sizes of the augmented implant designs. These implants were virtually implanted to correct 20° glenoid retroversion and the different mechanical parameters were calculated including: the glenohumeral subluxation force, relative micromotion at the bone-cement interface the glenoid, implant and cement mantle stress levels. The FEA model was then utilized to make measurements while the simulating abduction with the different implant designs. The biomechanical response parameters were compared between the models at comparable retroversion correction.Introduction
Materials and Methods
Augmented glenoid implants provide a new avenue to correct glenoid bone loss and can possibly reconcile current prosthetic failures and improve long-term performance. Biomechanical implant studies have suggested benefits from augmented glenoid components but limited evidence exists on optimal design of these augmented glenoid components. The aim of this study was to use integrated kinematic finite element analysis (FEA) model to evaluate the optimal augmented glenoid design based on biomechanical performance in extreme conditions for failure. Computer aided design software (CAD) models of two different commercially available augmented glenoid designs - wedge (Equinox®, Exactech, Inc.) and step (Steptech®, Depuy Synthes) were created per precise manufacturer's dimensions and sizes of the implants. Using FE modeling, these implants were virtually implanted to correct 20° of glenoid retroversion. Two glenohumeral radial mismatches (RM) (3.5/4mm and 10 mm) were evaluated for joint stability and implant fixation to simulate high risk conditions for failure. The following variables were recorded: glenohumeral force ratio, relative micromotion (distraction, translation and compression), and stress on the implant and at the cement mantle interface.Introduction
Materials and Methods
Computer navigation has been shown to decrease the variance of component positioning in primary THR. The cost of a navigation system in the U.S. however can exceed $200,000 in capital costs and $300–850 a case for disposables. Our objective was to assess the cost-utility of a hip navigation system. A review of the literature on costs and times for primary THR was done. Consecutive THR were done with an infrared navigation system. Total surgical time from incision to final skin closure and intra-operative time associated with the navigation process were recorded. Professional fees and the costs of revision surgery were estimated.INTRODUCTION
METHODS
