This is a Phase 3 randomized, double-blind, placebo- and active comparator-controlled pivotal study. Approximately 500 adult patients with moderate to severe pain due to OA of the knee will be enrolled and randomized. All patients will be followed for a total of 52 weeks. Efficacy and safety of 2 doses of TLC599 will be evaluated in comparison to Placebo and DSP through Week 52.