Pittsburgh Penguins defencemen Kris Letang has been retroactively placed on injured reserve dating back to Dec. 24, the team announced Thursday. Defencemen Chad Ruhwedel and forward Bryan Rust have also been placed on IR. Details regarding the gravity of the injuries to the players have not been disclosed. Subsquently, the Penguins have recalled goalie Casey DeSmith, defenceman Andrey Pedan and forward Garrett Wilson from the Wilkes-Barre/Scranton Penguins of the American Hockey League.