LE as a Marker for Periprosthetic Joint Infection

Inclusion Criteria: 1. Age greater than 18 years 2. Willing and able to sign the informed consent document 3. Subjects presenting with presumed aseptic failure of a prosthetic joint and expected to undergo revision arthroplasty, or subjects presenting with presumed PJI and expected to undergo either DAIR or radical implant resection, and subjects being investigated for PJI having joint aspiration outside of the operating room who may or may not require surgical intervention. Exclusion Criteria: 1. Subjects with known active crystalline deposition disease (e.g. gout) 2. Subjects with adverse local tissue reaction (ALTR) as a result of corrosion of components or metal-on-metal bearing surface in the hip 3. Subjects with active inflammatory arthropathy (e.g. rheumatoid arthritis) 4. Subjects undergoing a second-stage re-implantation procedure for PJI 5. Subjects in which standard of care assessments, at a minimum serology (ESR and CRP) and synovial fluid analysis (synovial WBC count, neutrophil percentage, and culture), cannot be performed. 6. Subjects in whom there is an insufficient amount of synovial fluid to perform the required investigational tests.