Causes

During activities that involve running, jumping and bending — such as soccer, basketball, volleyball and ballet — your child's thigh muscles (quadriceps) pull on the tendon that connects the kneecap to the growth plate at the top part of the shinbone.

This repeated stress can cause the tendon to pull on the growth plate where the tendon inserts into the shinbone, resulting in the pain and swelling associated with Osgood-Schlatter disease. Some children's bodies try to close that gap with new bone growth, which can result in a bony lump at that spot.