40 patients with knee osteoarthritis were randomized to three weekly injections of either Orthovisc (Anika Therapeutics) or Hylan G-F20 (Synvisc; Genzyme). Primary outcomes were synovial fluid concentrations of intercellular adhesion molecule-1 (ICAM-1) and vascular cell adhesion molecule-1 (VCAM-1). Clinical outcome on the Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) was also assessed. Results demonstrated significant within-group reductions in both groups for ICAM-1, VCAM-1, and WOMAC scores from baseline to 3 weeks, with no significant between-group differences observed.