Arthroplasty after septic arthritis of the native hip and knee: retrospective analysis of 49 joints

Background: Arthroplasty after septic arthritis (SA) treatment raises diagnostic and therapeutic questions. The main objective was to evaluate infection-free survival of patients undergoing total knee arthroplasty (TKA) or total hip arthroplasty (THA) post-SA. Other objectives were to describe the population's characteristics, surgical strategies, results of preoperative examinations and cultures of intraoperative samples taken at implantation, and postoperative antibiotic therapy. Methods: This is a retrospective, observational, monocenter study, from January 2005 to May 2019, including all patients undergoing TKA or THA with prior or ongoing SA in the same joint. Infection-free survival was analyzed and reported. Results: Forty-seven patients, 29 men, 49 joints operated on (30 knees, 19 hips), were included. Median SA-to-arthroplasty interval was 32 [1-216] weeks. It was $<2$ years for 43 joints and $<6$ months for 19 joints. Six patients underwent arthroplasty while still on SA treatment. One-stage arthroplasty was done for 43 joints and two-stage arthroplasty for 6 joints. Eight (16 %) cultures of intraoperative specimens were positive. Median durations of postoperative antibiotic therapy were 10 d for sterile cultures and 82 d for those that were positive. At 2 years, infection-free survival rate was 95.9 % ( $\pm 0.02$ ). After a median follow-up of 47 [18-142] months, no SA relapse was observed, but five patients developed new periprosthetic joint infections (PJIs) with a different microorganism. Conclusion: Arthroplasty may be a post-SA option, even within a short period of time. One-stage arthroplasty can be done if synovectomy is thorough, intraoperative samples are taken and antibiotics are administered until those culture results become available. We observed no SA relapse, but new PJIs occurred.