I did nothing to cause it. Suddenly I noticed when I bend my knee( no weight on it: Lift, etc) I feel a POP. I'm 30. Am I getting old or what? Or are my bones week? I have had quadracept injury in that leg before. But I never had a crack in the patella and below like I do now

Q: Lay down on a flat surface. Can you make your heel touch your buttocks?

No I can't.
Actually from my Quad tendon injury in 2000, ever since I have't been able t o do that. But this crack I ask about doesn't hurt, it just cracks while before this I would never get cracking/popping

I think you have to d some exercises to try to fix that. You als might have problems say sitting in a car or watching a movie for a long time, right?

The exercise has two parts.
1. While standing pull one knee toward tour buttocks as far as you can. Hold for 10 seconds or so. Repeat about 10x or wtaver is comfortable.

2. For the next exercise, put one foot on a toilet bowl (good height) and push down on the knee. Ditto Hold...

You need to strengthen those muscles. Do it slowly. You can do it anywhere. I was about 6" and something on the other leg. Now I'm about 1" and 0". I need to exercise it more.