Summary

Pseudoseptic arthritis is an increasingly recognised entity. It is an inflammatory arthritis that mimics septic arthritis; however, Gram stain and cultures are persistently negative. It is a diagnosis of exclusion. We present the first case, to date, in which pseudoseptic arthritis led to such severe joint degeneration that joint replacement surgery was required. A 54-year-old truck driver with rheumatoid arthritis, on immunosuppressive therapy, presented with acute onset severe left hip pain. He was given a clinical diagnosis of septic arthritis and treated with two prolonged courses of antibiotics despite persistently negative synovial fluid cultures. He experienced progressive joint destruction necessitating a two-stage total hip replacement. A retrospective diagnosis of pseudoseptic arthritis was made. This case demonstrates the difficulties inherent in differentiating between septic and pseudoseptic arthritis. This case also highlights the importance of accurate diagnosis and treatment for pseudoseptic arthritis to avoid accelerated joint destruction.