The role of elastoviscosity in the efficacy of viscosupplementation for osteoarthritis of the knee: A comparison of hylan G-F 20 and a lower-molecular-weight hyaluronan

The objective of this 12-week, double-masked, randomized, multicenter study was to compare the elastoviscous properties of a high-molecular-weight vis cosupplement, hylan G-F 20 (polymer concentration, 0.8%), with those of a l ower-molecular-weight hyaluronan (LMW HA) product (polymer concentration, 1 %) and to determine the relationship of elastoviscosity to efficacy in the treatment of patients with osteoarthritis (OA) of the knee. Patients had ra diographically confirmed primary idiopathic OA of the knee (Larsen grades I to V) with pain despite other treatments. After a 2-week washout period, 7 0 patients (73 knees) received three 2-mL intra-articular injections of tes t solution at 1-week intervals. Thirty-eight patients (38 knees) received h ylan G-F 20, and 32 patients (35 knees) received LMW HA. During the 12-week follow-up period, the primary outcome measures assessed by patients (using a visual analogue scale) were weight-bearing pain, most painful knee movem ent, and overall treatment response; the primary outcome measures assessed by study evaluators were weight-bearing pain and overall assessment of trea tment. The dynamic elastoviscous properties of the test solutions were meas ured on an oscillating Couette-type rheometer. Hylan G-F 20 was more elasto viscous than the LMW HA at all frequencies measured (0.001 to 10 Hz). At th e final evaluation, patients who received hylan G-F 20 had significantly be tter results on all primary outcome measures compared with those who receiv ed LMW HA. No systemic adverse events were reported. Local adverse events c onsisted of pain or swelling, noted in 2 of 38 knees injected with hylan G- F 20, and pain, noted in 1 of 35 knees injected with LMW HA (adverse event rates per injection, 1.8% and 0.9%, respectively). The difference in the in cidence of adverse events between groups was not statistically significant. The higher-molecular-weight, more elastoviscous hylan G-F 20 had significa ntly,greater pain-relieving effects than did the lower-molecular-weight, le ss elastoviscous hyaluronan.