A meta-analysis of 74 randomized trials with a total of 58,556 patients was recently published in the Lancet that looked at the effectiveness of NSAIDs in the treatment of osteoarthritis (OA) pain.
Briefly, their conclusion was that:
Acetaminophen is ineffective as a single-agent in the treatment of OA.
Diclofenac 150 mg/day had best evidence to support it as the most effective NSAID available presently with respective to its effectiveness in relieving pain and improving function.
They found no evidence that treatment effects varied over the duration of treatment ( no tolerance)
You can find the article here http://www.thelancet.com/journals/lancet/article/PIIS0140-6736%2816%2930002-2/abstract
References
da Costa, Bruno R, Stephan Reichenbach, Noah Keller, Linda Nartey, Simon Wandel, Peter Jüni, and Sven Trelle. “Effectiveness of Non-Steroidal Anti-Inflammatory Drugs for the Treatment of Pain in Knee and Hip Osteoarthritis: A Network Meta-Analysis.” The Lancet. Accessed March 21, 2016. doi:10.1016/S0140-6736(16)30002-2.
