Hello, naprosyn should not be taken for longer time. You should not use Naprosyn if you have a history of allergic reaction to aspirin or other NSAID (nonsteroidal anti-inflammatory drug). Naprosyn may increase your risk of heart attack or stroke, especially if you use it long term. Naprosyn may also cause stomach or intestinal bleeding, which can be fatal. These conditions can occur without warning while you are taking Naprosyn. Answer to severe patella femoral arthritis is total knee replacement. Thank you