I have had runners knee for over 7 months now. Initially i rested it for 2 months but nothing got better, then continued to rest into 3 months.
I started doing some squats, raises etc with just bodyweight no weights. 3-4 times a week for 12 weeks. It got slightly better but still continued with the pain and struggled to get to sleep a night as if I was not lying correctly.
In the last month I have started cycling. I did one spinning session as a trial with a gym. It instantly felt better. Since then I have rented and borrowed a bike twice and I feel 10 times better!
I think it definately helps and just gutted that i did not try it earlier!