Very rarely does X mark the spot of pain. Unless you fall and you hit your knee then obviously, X marks the spot.
But if you come in to see me and say I've got knee pain then I know you have knee pain.
But I also know that you have a movement problem somewhere that I've got to discover in order to find out WHY the knee is in pain in the first place.
Just because you have pain in your knee doesn't mean that it's caused by your knee.
And it's my job to find out just WHERE it is coming from and what we can do about it.