Acute pseudogout presenting as an exception to Musculoskeletal Infection Society criteria in total knee arthroplasty: a case report.

In this case, a 78-year-old female with no previous medical history of crystalline arthropathy presented with pain, effusion, and erythema about a total knee arthroplasty (TKA) performed 13 years prior. Implementation of a novel synovial fluid alpha-defensin assay ruled out periprosthetic joint infection (PJI) despite a positive 2018 Musculoskeletal Infection Society (MSIS) minor criteria score of 8 points, a significant diagnostic differentiation which prevented secondary invasive debridement or joint irrigation intervention. Confirmatory histologic study was positive for calcium pyrophosphate crystals, indicative of acute pseudogout inflammation rather than PJI or septic arthritis manifestation.

Late hemorrhagic pseudoseptic arthritis encountered during total knee arthroplasty due to hyaluronic acid viscosupplementation.

Osteoarthritis (OA) is the most common form of arthritis and affects approximately one-third of people in the United Sates aged 65 years and older. Since 2013, the American Academy of Orthopaedic Surgeons has not been able to recommended using hyaluronic acid for patients with symptomatic OA of the knee. Subsequent publications have also cautioned against the use of viscosupplementation based on lack of efficacy and the potential for harm.