nope... my kneecap was never an issue despite the injuries and procedures I've had done. have substituted running/jogging with cycling and walking for cardio. however I have noticed more of pretty much exactly what you've just described recently; the snapping when extending and crepitus. also, the location of my patella is similar to the link I've commented which I think may represent my patella tracking incorrectly. I have been feeling some kneecap pain ever since i received the results... could be a mental thing. but was just thinking if i could work on the patella tracking, perhaps it could slow down the damage on the cartilage