The loaned-out Irish international was replaced at the beginning of the second half at the Valley and was placed into a protective boot before the end of the game.
Sky Sports delivered an update on the knock for Cullen, who suffered suspected ligament damage and is now set for scans on Monday to find out the extent of the damage.
“Suspected ankle ligament damage,” as spoken on Sky Sports’ commentary of the game.
The 23-year-old had completed every single minute of the Championship season under Lee Bowyer but is now set for a spell on the sidelines.
This is a massive blow for Cullen and any hopes he could have had of returning to West Ham this season and potentially cementing a spot in the Premier League. Manuel Pellegrini isn’t exactly in the middle of his greatest run at the club, and with Carlos Sanchez not necessarily the player to turn it around, the fresh legs of Cullen could have given the Hammers a real boost. The 23-year-old has been superb for the Championship side this season and has been one of their standout players in the middle of the park. The Irishman is at the heart of everything for the Addicks and has the ability to get on the ball and make his side tick in important periods of games. Cullen has averaged 47.7 passes per game according to WhoScored – the second most in Charlton’s squad, as well as the most key passes of any player with 1.5. Instead of catching the eye, Cullen will now be on the sideline for the near future, something that will all-but end his hopes of being recalled.