GLOSSARY

Osgood-Schlatter disease can cause a painful lump below the kneecap in children experiencing growth spurts during puberty. Osgood-Schlatter disease occurs most often in children who participate in sports that involve running, jumping and swift changes of direction — such as soccer, basketball, figure skating and ballet.

While Osgood-Schlatter disease is more common in boys, the gender gap is narrowing as more girls become involved with sports. Osgood-Schlatter disease affects as many as one in five adolescent athletes.

Age ranges differ by sex because girls experience puberty earlier than do boys. Osgood-Schlatter disease typically occurs in boys ages 13 to 14 and girls ages 11 to 12. The condition usually resolves on its own, once the child's bones stop growing.