An ole mate of mine, now 64 had his knees done about 10/12 years ago.
Before he had them done, he had sold all his guns because of the pain when going out and not being able to get about as he would like.
Now he's like a spring bloody chicken, he is careful so wears knee pads for crawling etc, but the places he gets are quite unbelievable.
We did the hill for a week last year, and go upto our syndicate ground twice a year for a week.
Last year our chiller was out of action so we hung our deer over night in a tree to keep em cool, I called him on the radio to say I was on my way to help hang the deer up.
I got to where we had agreed and couldn't find him, I called him on radio asking "where are you", the reply was " up here! " he was laughing 12 foot up a tree with the 2 does!
Good luck fella.