Anyone got some advice for me please? I injured my left knee many years ago, up till now it's been fine when running, but the other day I took a slightly longer step than usual to reach the kerb, and my back leg (left knee) sort of twanged...it hurts when I bend my knees, but is ok most of the time. I haven't run since - any suggestions? Go out and try it? Rest it till it's completely gone? See the doc?