Background
According to crew statements, the flight crew briefed the flight attendants that turbulence was forecast for the flight and that they would keep them updated throughout. During the first portion of the flight, the flight encountered light turbulence and occasional moderate turbulence several times, and the flight crew made public address (PA) announcements each time.
Incident
Later, the flight encountered unexpected turbulence and the flight crew immediately turned on the fasten seatbelt sign and made a PA announcement. At that time, a flight attendant was stowing a beverage cart in the aft galley. The turbulence caused the cart to bump the flight attendant's hand.
Aftermath
The flight attendant continued to perform her duties, and the flight landed uneventfully. The following day, the flight attendant's hand was painful and swollen, and she was diagnosed with a broken wrist.