The Risk of Acute Infection Following Intra-articular Corticosteroid Injection Into a Pre-existing Total Knee Arthroplasty

No previous studies have investigated the risk of infection following intra-articular corticosteroid injection (IACI) into a pre-existing total knee arthroplasty (TKA). The aim of this study is to determine the risk of acute infection following IACI into a pre-existing TKA. A retrospective chart review identified all patients at a single institution between October 2009 and May 2015 that had an ipsilateral knee injection subsequent to a TKA. The risk of acute infection, as defined by development of an infection within 3 months of IACI, was determined via review of clinic notes, operative reports, laboratory records, and telephone interviews. A total of 1845 injections in 736 patients met the inclusion criteria. In total, 101 (4.8%) patients were lost to follow-up. Three infections in 3 patients occurred within 3 months of IACI, yielding an infection rate of 0.16% per injection, or 1 infection in every 625 IACIs following TKA. This study is the first to investigate the risk of acute infection following injection of corticosteroid into a pre-existing TKA. Given the dire consequences of infection following TKA, the routine use of IACI into a pre-existing TKA should be avoided, and a thorough workup should be performed in any patient with a painful TKA prior to consideration of IACI.