D.S.
Greetings G., I have to say as the mother of 5, with one being a very active girl-- that those knees will be fine i no time and you will miss the days of her youth and how she played.
I have a grandchild that is as busy as it gets and it always amazes me that no matter how dirty and hard she plays her smile will win hearts and her excitment of life is wonderful-- she cleans up real well too!