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Background: Historically, there has been excellent survivorship of total hip arthroplasty with newer implants expected to outperform prior generations. Review of our institutional database identified problems with one particular cross-linked polyethylene liner in mid-term follow-up, which has not been reported in the literature. We report on the technical aspects of this liner, as well as the clinical and radiographic factors associated with early failure of this bearing in our practice., Methods: A retrospective review of our institutional database was performed from January 2009 to June 2019 of patients who presented with significant osteolysis in the setting of prior total hip arthroplasty with a contemporary polyethylene liner. Demographic and radiographic measures were collected for all patients., Results: Twelve patients were identified, with nine undergoing revision surgery. All patients demonstrated radiographic osteolysis at the time of revision surgery. The average time to diagnosis of failure was 55.9 months (range: 12-120 months). Average cup position preoperatively was 44 degrees inclination (range: 36-53 degrees) and 21 degrees anteversion (range: 10-34 degrees). Nine patients underwent revision of the acetabular component, with two also undergoing femoral component revision. The Manufacturer and User Facility Device Experience database revealed 22 reported cases of wear-related failure from 2009 to 2019., Conclusions: Considering that no identifiable risk factors related to patient demographics or implant position were identified, the Exactech Connexion GXL liner may be prone to a high rate of early failure from wear and severe secondary osteolysis. We recommend close surveillance of patients with this bearing surface., (Copyright © 2020 Elsevier Inc. All rights reserved.)

Background: Diagnosing periprosthetic joint infection after total joint arthroplasty is often challenging. The alpha defensin test has been recently reported as a promising diagnostic test for periprosthetic joint infection. The goal of this study was to determine the diagnostic accuracy of alpha defensin testing., Methods: One hundred and eighty-three synovial alpha defensin and synovial fluid C-reactive protein (CRP) tests performed in 183 patients undergoing evaluation for periprosthetic joint infection were reviewed. Results were compared with the Musculoskeletal Infection Society (MSIS) criteria for periprosthetic joint infection., Results: Alpha defensin tests were performed prior to surgical treatment for infection, and 37 of these patients who had these tests were diagnosed by MSIS criteria as having infections. Among this group, the alpha defensin test had a sensitivity of 81.1% (95% confidence interval [CI], 64.8% to 92.0%) and a specificity of 95.9% (95% CI, 91.3% to 98.5%). There were 6 false-positive results, 4 of which were associated with metallosis. There were 7 false negatives, all of which were associated with either draining sinuses (n = 3) or low-virulence organisms (n = 4). A combined analysis of alpha defensin and synovial fluid CRP tests was performed in which a positive result was represented by a positive alpha defensin test and a positive synovial fluid CRP test (n = 28). Among this group, the sensitivity was calculated to be 73.0% (95% CI, 55.9% to 86.2%) and the specificity was calculated to be 99.3% (95% CI, 96.2% to 99.9%). An additional combined analysis was performed where a positive result was represented by a positive alpha defensin test or positive synovial fluid CRP test (n = 64). Among this group, the sensitivity was calculated to be 91.9% (95% CI, 78.1% to 98.3%) and the specificity was calculated to be 79.5% (95% CI, 72.0% to 85.7%)., Conclusions: Alpha defensin in combination with synovial fluid CRP demonstrates very high sensitivity for diagnosing periprosthetic joint infection, but may yield false-positive results in the presence of metallosis or false-negative results in the presence of low-virulence organisms. When both alpha defensin and synovial fluid CRP tests are positive, there is a very high specificity for diagnosing periprosthetic joint infection., Level of Evidence: Diagnostic Level III. See Instructions for Authors for a complete description of levels of evidence.