Though I never got as far as requiring surgery from sports in my youth (baseball and soccer) my knees have never been 100%
I just turned 40, and wish now that I never played to the extent that I did. There's not a day that goes by that I don't have pain, or limitations in what I can do as a result of my injuries.
It sounds to me that your son has pushed himself much farther than I ever did.
WWhermit
