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Bilateral symmetric inflammatory reaction to hylan G-F 20 injection

“…Inflammatory reactions have become a recognized complication of hylan G‐F 20 injections used in the treatment of knee osteoarthritis (OA) (1–3). These reactions occur within 24–48 hours of injection, causing increased joint pain, sometimes accompanied by swelling and erythema (4).…”

“…The trigger for joint inflammation in these cases is unknown. Inflammatory reactions occurring after the first hylan G‐F 20 injection have not been reported, but synovitis can occur following subsequent injections, sometimes in the same joint repeatedly if additional injections are administered (1–3). In the case described below, symmetric inflammatory knee effusions occurred following the first bilateral knee injections in a second course of hylan G‐F 20.…”

“…The buffered saline vehicle used in the administration of hylan G‐F 20 probably does not play a role in inflammatory reactions, nor do other contaminants or additives (1). Recent interest has focused on the role of small hyaluronic acid fragments as proinflammatory mediators; such fragments might arise from degradation of hylan or sodium hyaluronate administered via injection (3).…”

“…The strikingly symmetric response in this case suggests a highly specific reaction to hylan G‐F 20, with subsequent development of joint inflammation. The lack of reports of inflammatory responses following first exposure to hylan suggests that sensitization is required for joint inflammation to develop (3). The symmetric response reported here (and the recurrent reactions reported elsewhere) suggests that some individuals may be uniquely susceptible to inflammatory responses.…”