A new study out of the Mayo Clinic finds broken arms are on the rise among adolescents. Researchers in Rochester say that, over the last 30 years, forearm fractures have increased 42 percent. Dr. Sundeep Khosla is the author of the study and a professor of medicine in Mayo's department of endocrinology. He says doctors had theorized that more fractures occur during adolescence because bones become more porous during growth spurts. But he says the study indicates there are a variety of reasons why fractures have increased so drastically over the last three decades.