Okay w/OS
I'm 36, ski hard, bike, roller blade, lift weights, and have a "golf ball" under each knee. I don't run for excercise. I did for a while several years ago, but it aggrevated one knee and created problems for the other. I hike and backpack a couple times a year. I can kneel, but not directly on the knobs. Gauging from some of the stories here, I'm fortunate.
Here's what works for me: Strengthening my hamstrings, glut's (and lower back), keeping them limber, and using them in balance with my quads. (Doing squats and leg presses with GOOD FORM is great for this.) Focusing on using the muscles in the back of my leg for anything that requires pushing-off or absorbing impact allows me to do most anything, at least occasionally, without problems. It took a long time to learn this.
I don't know if this would have helped in my teens, but if someone had suggested it, I'd have tried. For teens who have OSD: Seek advice from as many sources as possible. My guess is you'll have to take it easy for quite a while and then learn how to use your body in a way that doesn't aggravate your OS. Be very cautious about surgery or medication. Know ALL the LONG TERM RISKS! Keep in mind that your knees (and your back) are for life. Treat them well!!
Take care.
From:
dleggett@mapcorp.com