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. We present a case of late hemorrhagic pseudoseptic arthritis encountered during TKA due to hyaluronic acid viscosupplementation. Our triad of findings includes (1) acute and chronic inflammatory cells on frozen section, (2) synovitis with hemosiderin deposition, and (3) blackened cartilage with iron deposition on permanent histopathology. Our case is unique in that it shows a previously undescribed late complication of viscosupplementation.