I just returned from running this week after a 7 week hiatus because of "runners knee". Currently I am in a mountains area. I am afraid that if I run up a hill, which I enjoy, that I will be only able to walk down the hill because I do not want to aggravate my knee. Am I just being a puss or is my fear justified. Today I ran up a 2 mile climb then walked it down. The hills are to tempting.
If it is steep(8+%), walk down until you are close to the bottom. what this will do is it will strengthen your knee to the point where it can take the impact of running downhill
If it is moderately steep(5-8%), maybe do the same as above for the first week or two, but after that start with jogging down it
If it is shallow(1-5%), do not worry at all about striding out (to a controllable extent)
Puss.
In addition, providing this does not aggravate the knee:
go out on a long HIKE, walk the flats and up hills, but let your stride go on the downhills (to your control)
On *really* steep downhills, don't be afraid to walk down backward! Lots less stress on the knee, and probably safer.