Is my knee about to give out? For the last couple of weeks or so my knee seems to be on the way to giving in now and again. I get this slight pain (more at sensation) like my knee is about to not stop the forward motion as the upper and lower leg straighten together. The sensation is at the top and behind of the knee cap. It happens with little stresses like shifting form one leg to the other, or walking etc. It happens only occasionally. Has anyone ever had this happen as a pre-cursor to a knee injury?