Acute pseudoseptic arthritis after viscosupplementation of the knee: a case report.

Intra-articular injections of hyaluronan are generally well tolerated; the most common adverse event associated with their use is an inflammatory reaction or a flare at the injection site. Naturally derived sodium hyaluronates have not been associated with pseudosepsis; we describe a case of severe arthritis mimicking acute septic arthritis after naturally hyaluronan. A 70-year-old woman had a medial femorotibial and patellofemoral compartment knee osteoarthritis. Hyaluronic acid injection was indicated because of the persistence of a pain while walking and restricted ability to walk 100 m, as well as the installation of a flessum. She was admitted for an evaluation of a joint effusion occurring within 48 h after the first hyaluronic acid intra-articular injection (first course), with no fever or chills. Joint fluid was found to be cloudy and contained 24,000 cells per mm(3). A knee aspiration was performed to evaluate the possibility of a joint infection. The examination of synovial fluid under phase contrast and polarizing microscopes showed no crystals, and culture on standard media was negative. Acute septic arthritis was considered to be the most likely diagnosis, and probabilistic antibiotic therapy was started. The result of the bacteriological examinations also returned negative. The absence of general signs, particularly fever and chills, with fast effusion regression in less than 4 days did not plead in favor of a septic origin. In front of this beam of arguments, antibiotic therapy was stopped after 4 days. The nonsteroidal anti-inflammatory drug (Nimésulide) was given. The clinical and laboratory test abnormalities were normalized within 2 weeks. Our case has the particularity to occur after using Curavisc, which is known as producing no allergenic reactions. Moreover, the described reaction occurred with the very first infiltration within the very first course.