Osgood Schlatter disease is an inflammation of the patellar tendon, where the knee meets the top of the tibia (shinbone).
The disease is most common in active boys aged 10-14. It most commonly occurs in just one leg but can occur in both at the same time.
The condition is caused by stress on the tendon that attaches the muscle at the front of the thigh to the tibia.
Symptoms include swelling and tenderness and usually appear slowly.
Treatment includes rest and analgesics. Immobilization of the knee by a cast may be required if the problem persists.