This will be the phase III randomized, double-blind, placebo-controlled trial of 52 weeks duration designed to evaluate the efficacy of sodium hyaluronate to placebo (saline), in adult with OA of the knee joints. Randomization will be stratified by Kellgren-Lawrence(KL) grade (garde2 or 3), by subjects X-ray. A total of 60 subjects are planed for enrollment in this study. The study will be conducted over approximately 52 weeks.