Osgood-Schlatter disease is a knee problem that causes pain and swelling in the shinbone (tibia) just below the kneecap (patella). This is the spot where the patellar tendon attaches to a bony mound in the knee called the tibial tubercle.

The disease is caused by too much stress on the muscles and tendons that support the knee. Repeated stress can cause the patellar tendon to pull away from the shinbone. This can cause pain and swelling.