Clinical effects of intraarticular injection of high molecular weight hyaluronan (Orthovisc) in osteoarthritis of the knee: a randomized, controlled, multicenter trial.

Objective: To evaluate the efficacy and safety of injection of high molecular weight (HMW) hyaluronan (Orthovisc) in patients with mild, moderate, and severe knee osteoarthritis (OA).

Methods: A randomized, arthrocentesis-controlled, multicenter trial. Patients (n = 372) were randomized to 4 weekly HMW hyaluronan injections (O4, n = 128), 3 weekly HMW hyaluronan injections followed by one arthrocentesis (O3A1, n = 120), or 4 arthrocenteses without injection (control group, A4, n = 124). All patients had knee OA, as determined by Kellgren-Lawrence (K-L) grade, and Western Ontario and McMaster University Osteoarthritis Index (WOMAC) pain score > or = 200 mm and < 400 mm in index knee and < 150 mm in contralateral knee. The primary outcome measure was the proportion of patients achieving a 20% relative and 50 mm absolute improvement from baseline in WOMAC pain score at Weeks 8, 12, 16, and 22 post-baseline in the index knee. Secondary outcomes were Patient Global score, Investigator Global score, and Pain on Standing score.

Results: The evaluable subgroup consisted of patients with K-L grade 2 or 3 at baseline. The comparison of O4 versus A4 for the primary outcome approached, but did not reach, significance in the evaluable subgroup: 76% of O4 patients had > or = 20% improvement in WOMAC pain score at Week 8 compared to 62% of A4 patients. More O4 patients had > or = 40% improvement in WOMAC pain score compared to A4. The effectiveness of the 3-injection regimen (O3A1) was masked by a possible placebo effect from the needle injection procedure in the A4 (control) group. No differences between groups were observed with respect to incidence of adverse events.

Conclusion: Our findings indicate that HMW hyaluronan is safe and seems to be effective in the treatment of mild to severe OA of the knee.