Great news.
In terms of flying (back it up by the AME blah blah), retaining functionality is of utmost importance.
As we get older, we've all got some degree of OA. It's a bit like getting grey hair.
Pain relief is important, have a look at the WHO pain ladder for further guidance, but be aware that some of the "adjuncts" probably aren't compatible with flying. I guess codeine based stuff should be best avoided if possible.
Regular paracetamol is bottom of the ladder, underrated, but often very effective.
Diclofenac is usually very effective. It's an "NSAID" and guess what? - they have their own "ladder." Diclofenac is mid way up the ladder, ibuprofen is bottom of the ladder. Naproxen is somewhere inbetween. I prescribe, (and use!) a lot of it.
Long term use of nsaids is not always ideal, it has been associated with sudden death, gastric bleeding and kidney problems. It can also put your blood pressure up. The higher up the ladder, the higher the risk.
As always, it's a risk/benefit equation, and there's lots of other factors to consider-if required long term, chat to your prescriber.