What exactly is Osgood Slaughter Disorder, and what can help it?

My teenage son has been diagnosed with Osgood Slaughter Disorder in his knee. Supposedly it's something he is likely to outgrow. We were told he shouldn't stress it, but he really needs more physical activities because he's overweight. Any info would be helpful. For example, would a knee brace help him be able to run or jump? Will ice packs help with pain? Would losing his excess weight help speed up the "healing" process, or at least lessen the pain? Are there any helpful hints anyone out there can share with us?
He tries to use the knee problem as an excuse not to do various things, and I would like some logical arguments to counter his with. Whether it's medical advice, personal experiences, or whatever...bring it on. Thanks!

"Osgood-Schlatter disease is a common condition in children often referred to as growing pains of the knees. Osgood-Schlatter disease is the result of rapid growth and pulling of the tendons around the growth plate of the knee in adolescents. The large quadriceps muscle of the front of the thigh attaches to a bump over the front of the shin bone. When this large muscle contracts, it pulls on this tendon. Over time, repetitive pulling, combined with the growth taking place in the bone, causes irritation of the growth plate. Osgood-Schlatter is most common in active adolescents."

My son was diagnosed with Osgood-Schatter disease when he was going through a very rapid growth spurt in his early teens. He actually had to wear a cast for a few months. Today, about 10 years later, he has no problems with his knees, or legs, is very healthy and very active in all sports, particularly skiing and mountain biking.

Lots more information on this disease listed below. Hope that helps.

talk to his doctor

the previous poster pretty much hit the condition nail on the head. It basically happens when the an adolescent's bones grow faster than the tendons and muscle. The tendon can actually pull away bone from the growth plate that is very painful. I suffered from it from about the age of 12-16 and was active in soccer, volleyball, track and field and basketball. Ice and ibuprophen help a lot. A simple ice cup (fill a dixie cup or styrofoam cup with water, freeze and then rub the block on the affected area for 20 minutes) helped me tremendously. I'd say that hardcore activities such as running or jumping will make the pain more pronounced, but it didn't stop me from participating in activities and swimming might be a good activity if you have access to a pool. I honestly remember the pain being the worst at night when I was lying in bed, I literally cried myself to sleep on several occaisions so it's a real pain (I also grew 9 inches in six months) so things happen. Eventually it will resolve itself and he'll be fine, but it's no excuse not to be active.