The joke in the valley here is how many people have a "6 pack" --- that is --- both knees - both hips - and both shoulders.... There's so much impact done to these joints (areas) here - and the average age of some of these sports/activity nuts - they've just worn the stuff out. LOL
Gwen needs both her knees done - but keeps putting it off.... because there's always some bike ride coming up (just did a Centurion - 100 miles in one day - in Maine last week - and is headed to Croatia for a multi day bike tour).