Osgood-Schlatter is not really a disease. It's an overuse syndrome -- a set of symptoms that happen at the same time and with excessive activity. Young athletes usually get Osgood-Schlatter during their rapid growth years (ages 9-13). Youths who are extremely active in sports may be vulnerable. It happens more often in boys, but girls can develop it at younger ages.

Causes
The pain comes from repeated pulling of the kneecap (patellar) tendon. Repetitive, overuse injuries may make the tendon inflamed at the spot where it connects to the shinbone (tibia). Fast growing bone is susceptible where the tendon pulls on it. The tendon may get inflamed or even tear away, sometimes taking a tiny piece of shinbone with it.

Symptoms
If your child has tenderness, swelling and an aching pain beneath his knee joint, it may be Osgood-Schlatter disease. The pain gets worse when your child is active and better when he or she rests. It's a common and temporary condition. Usually Osgood-Schlatter affects only one knee. Look for a slightly swollen, warm and tender bony bump below your child's kneecap. The bump hurts when you press it. It may hurt at night or when your child is kneeling, jumping, climbing stairs, running, lifting weights or engaging in any activity that bends or fully extends the leg.

Treatment
Don't ignore the pain---rest the knee until it gets better. With rest, Osgood-Schlatter usually heals itself within 6 to 18 months. But ignoring the pain will make the condition harder to treat and it might even come back again later in life.

It is not necessary to stop participation in sports altogether--just limit the activity. While your child heals, he can use a pain reliever like ibuprofen to reduce pain and swelling. You may also try icing the area after sports and/or using a protective knee pad. If the pain does not go away, your doctor may want your child to wear a brace or a cast. Once the pain is completely gone, he can slowly return to his old level of activity. Your doctor may recommend certain stretching and strengthening exercises to help avoid developing the Osgood-Schlatter condition again in the future.