Pseudoseptic arthritis as a complication of intra-articular infiltration of hyaluronic acid in a patient with rheumatoid arthritis.

Pseudoseptic arthritis is a rare complication of hyaluronic acid (HA) injections that often is difficult to differentiate from septic arthritis. Patients present acute pain, swelling and joint effusion normally around 24h after the second or third HA infiltration. We describe a female patient with seropositive rheumatoid arthritis and flare-ups of knee arthritis with pseudoseptic features in the past, who develops pseudoseptic arthritis of the knee following her first injection of hyaluronic acid.