There is a link between a runners knee pain and weak knees. In an article in runners world magazine two runners who suffered chronic knee pain recovered after they were put on a program of hip strengthening exercises.
Reed Ferber Hip Strengthening Exercise.
The article has a program demonstration by Reed Ferber, Ph. D., director of the University of Calgary’s Running Injury Clinic. He recommends doing them daily after you run. Start with one set of 10 reps and gradually increase sets so that you’re doing three sets of 10 by your fourth day. You should see improvement in two weeks. If you don’t, Ferber says to see a doctor because the cause of your injury may lie elsewhere.
See and read the technique at this article @Runners World.
Check out this video demonstration of Hip Strengthening exercise