An old mate of mine had both his knees replaced, due to sporting injuries sustained during his youth. The first was great the second not so great,it left him with limited movement in his left knee. He was carrying a bit of weight though.
He was adamant that he had done the right thing and that although he had restricted movement, he didn't have to suffer the pain any more.
Talk with your surgeon and weigh up the benefits and possible difficulties if it does not prove successful.
