From The American Academy of Orthopedic Surgeons
http://orthoinfo.aaos.org/topic.cfm?topic=A00273
"Skateboarding is an activity in which you move quickly over hard surfaces. It can lead to injuries that range from minor cuts and bruises to catastrophic brain injury. Each year in the United States, skateboarding injuries cause about 50,000 visits to emergency departments and 1500 children and adolescents to be hospitalized. (Source: AAP, March 2002. )
Most hospitalizations involve head injury. Even injuries that heal quickly can cause pain and anxiety, cost time, and money and may lead to disabilities. This can include loss of vision, hearing and speech; inability to walk, bathe, toilet, dress or feed yourself; and changes in thinking and behavior. "
David