Word of warning,

My father played collegiate basketball back in the 70's. His whole body below his waste orthopedically is FUBAR'd now. He had his right knee replaced one year ago, and is still having difficulties getting around. He's getting better, but in his opinion, he was better before the surgery. His knee wont pop out of joint anymore, but he's in much more pain. Of course, Dad's a 6'8" 300lbs guy, probably quite different physically from your wife (I hope) :P