Objective: To determine efficacy and safety of intraarticular (IA) hyaluronic acid (HA; Hyalgan) versus placebo and a nonsteroidal antiinflammatory drug for osteoarthritis (OA) of the knee.
Method: A series of 5 weekly IA injections of HA (20 mg each) was compared to placebo or oral naproxen in a 26 week, double blind, masked observer, multicenter trial of 495 patients with idiopathic OA. Acetaminophen was permitted for escape analgesia. The primary measurement was pain experienced on a 50 foot walk test for those completing the study (completers) as measured on a 10 cm visual analog scale (VAS). Also measured were the Western Ontario and McMaster Universities (WOMAC) Osteoarthritis Index (pain, stiffness, function) and categorical assessments of pain.
Results: Patients receiving HA improved more with respect to pain on the 50 foot walk compared to placebo at Week 26 (HA vs placebo difference 8.8 mm; p < 0.005); 56% of HA treated patients compared to 41 % of placebo treated patients had > or = 20 mm reduction in the VAS from Week 5 continuously through Week 26 (p=0.031). At 26 weeks, more HA treated patients (47.6%) had slight pain or were pain-free in contrast to placebo treated (33.1%; p=0.039) or naproxen treated (36.9%; p=0.22) [corrected] patients. Improvement in secondary outcome variables was generally superior in the HA group compared to those receiving placebo and was significantly better at Week 26 with respect to the WOMAC pain (p=0.041) and WOMAC physical function (p=0.047) subscales. The HA group also tended to have better results relative to the naproxen group in both primary and secondary assessments. For all randomized patients, there was a > or = 20 mm improvement in pain experienced on the 50 foot walk in 28% [corrected] of placebo treated patients vs 36% [corrected] of the HA treated patients (p=0.127; 67% of patients completed the trial). Injection site pain, more commonly reported in the HA group (38/164=23%) than in the placebo group (22/168=13%; p < 0.001), resulted in withdrawal in 6 patients (4%). One withdrawal was associated with the HA injection (< 1%). Gastrointestinal adverse events were significantly more common in the naproxen group than the HA or the placebo groups and 14 naproxen treated patients (8.3%) discontinued prematurely due to these events.
Conclusion: This large, controlled randomized clinical trial confirms that 5 weekly IA injections of HA (Hyalgan) in patients with OA of the knee are generally well tolerated, provide sustained relief of pain and improved patient function, and were at least as effective with fewer adverse reactions as continuous treatment with naproxen for 26 weeks.