Conversion of Unicompartmental Knee Arthroplasty to Total Knee Arthroplasty for Cement Allergy.

Despite the success of unicompartmental knee arthroplasty (UKA) and total knee arthroplasty (TKA), complications leading to loosening and eventual failure can arise. While infection, instability, and aseptic loosening are some of most common causes of UKA and TKA failure, one of the less common reasons is delayed hypersensitivity reactions. While most allergic reactions are hypersensitivity reactions to metal, hypersensitivity reactions to other materials used in the procedure, such as polymethylmethacrylate bone cement, have begun to gain more attention in recent years. In this case report, we explore the unique instance of a patient who required a revision of a cemented UKA to TKA due to severe pain likely caused by a confirmed polymethylmethacrylate allergy.