That is awesome he is doing great and not experiencing any pain. Take it from me as a former catcher to take care of his knees. Ice should be his best friend. I wish someone would have told me the things I should have done to keep them healthy. I didn't have Osgood Schlatters but I did dislocate my left kneecap 4 times in high school.
It constantly hurts and I am very slow going up steps (it figures my classroom would be upstairs too). Some days when the weather is bad I want to curl up in the fetal position and cry like a baby.
Take care of his knees.