Have a word with Harry Potter, may have a potion for Levitation!! If you could bring the ground up to waist level, then that will reduce any knee problems :boogy:
Perhaps on a more serious note, wear leggings -prolonged cold & wet knees and pain go together, wear good quality knee pads, reduce your age, bet you never had any problems aged 20 or 30.
I had a cartlidge repair to my knee a couple of years ago, told my knee was a grade 3, asked if that was good? Consultant said they only go up to grade 4, oh dear