Daily use of NSAIDs over a long term, can have serious side effects and is not recommended.Substituting, another NSAID is not the answer. If you truly have developed post-traumatic arthritis as a result of previous meniscus injury, there are several alternatives. Viscosupplementation with hyluronate injections, such as Synvisc, can be very helpful. Natural anti-inflammatories such as Glucosamine or Omega-3 are very useful alternatives. (I favor the omega-3) In addition, if you are overweight, then weight control is imperative. Finally, I have become a big proponent of acupuncture for orthopedic problems, and my experience has been that when combined with traditional orthopedics, acupuncture can have a synergistic effect.
I'm not a Dr. but I do know that NSAIDs such as motrin are not safe taken everyday. It is hard on your stomach but also can cause kidney issues. In talking to a nephorologist (msp? -kidney Dr.) she said that they have wanted that disclosure put on such meds. Every drug has something bad about it but one definetly has to try a pick the lesser evil. Talk to a pharmacist & then talk to your Dr. Take care!