NSAIDs control the pain and inflammation associated with osteoarthritis.
They work by blocking the production of prostaglandins, the chemicals that cause inflammation, in the COX pathway. COX stands for cyclooxygenase, which is another enzyme in the pathway that breaks down the arachidonic acid in the cell membranes of the joint into chemicals such as free radicals and various prostaglandins that damage the articular cartilage.
Full article Longlife: NSAIDs Research Article