AIM: To study the effect of intra-articular injection of hyaluronic acid in treating knee osteoarthritis. METHODS: Ninety patients (M 38, F 52; age 65±s 8 a). with knee osteoarthritis were randomly divided into 3 groups, 30 patients in each group. Group A received hyaluronic acid 2.5 mL intra-articular injection, qw×3 wk; group B received diclofenac tablets 50 mg, po, bid for 3 wk; and group C received steroid preparation (triamcinolone acetonide injection 20 mg+0.5% bupivacaine injection 5 mL+0.9% sodium c...