Complex sentence: Cohen did not compete at the 2001 Nationals due to a stress fracture in her back, but took back her silver medal at the 2002 U.S. championships, earning her a trip to the Olympics.
Split into simpler sentences: Cohen did not compete at the 2001 U.S. Nationals due to a stress fracture in her back. Cohen won the silver medal at the 2002 U.S. championships, earning her a trip to the Olympics.