Abstract
<title>Abstract</title> <p>Periprosthetic gout flare following total knee arthroplasty (TKA) is exceedingly rare; however, it can clinically mimic acute periprosthetic joint infection (PJI) by presenting with joint erythema, swelling, pain, and fever. We report a case involving a 68-year-old male with no prior history of gout who underwent right TKA for primary osteoarthritis. Six weeks postoperatively, he developed a fever (38.3°C) and erythema of the right knee, accompanied by functional limitation. Laboratory findings indicated elevated C-reactive protein (CRP) levels (82.57 mg/L) and an erythrocyte sedimentation rate (ESR) of 38 mm/h, with serum uric acid measured at 504 µmol/L. Synovial fluid cultures were negative. Empirical antibiotic treatment did not alleviate symptoms, whereas administration of anti-gout medication resulted in prompt clinical improvement. Radiographs taken at 12 weeks revealed peri-prosthetic dense opacities suggestive of crystal deposition. This case underscores that the current Musculoskeletal Infection Society (MSIS) and European Bone and Joint Infection Society (EBJIS) diagnostic criteria cannot reliably differentiate PJI from crystal-induced arthropathy, as both conditions exhibit overlapping inflammatory markers. Synovial fluid crystal analysis using polarized microscopy remains crucial to prevent misdiagnosis and unnecessary surgical interventions. Clinicians should maintain a high index of suspicion for periprosthetic gout, even in patients lacking a known history, and consider a therapeutic trial of anti-gout medication when infection is not confirmed.</p>