Are there distinctive inflammatory flares after hylan g-f 20 intraarticular injections?

This survey was designed to examine features of a group of patients with acute painful joint effusions following hylan G-F 20 (Synvisc) knee injections.

Eight patients with painful local reactions after intraarticular hylan G-F 20 injections for knee osteoarthritis were evaluated clinically, with detailed synovial fluid analysis, and followed for outcome.

Leukocyte counts ranged from 3150 to 103,000/mm3. Crystals were seen in one patient. Inflammatory knee effusions occurred from 1 to 48 h after injections, but never with first injections. Synovial fluid volumes were 30 to 71 mm(3). Three patients had shiny clumps (not further characterized) that were noted in leukocytes on Wright stained smears. Most patients were treated with aspiration and depot steroids. Five of the 8 patients had moderate or greater improvement at 6 months.

The majority of the occasional dramatic episodes of inflammation after hylan G-F 20 injection do not seem to be related to crystals. No detrimental lasting results were noted. The absence of post-hylan flares following the first intraarticular injection in this small series suggests that sensitization to or accumulation of hylan G-F 20 or its breakdown products may play an etiologic role in these flares.