Coach Lindy Ruff said the team will evaluate Sekera, 22, in at least a couple of weeks -- "or maybe longer" -- after Chicago forward Dustin Byfuglien checked him into the boards in the second period of Buffalo's loss to the Blackhawks on Wednesday.
Sekera had played in every Sabres game, registering a goal and 13 points in 43 contests and averaging over 22 minutes of ice time per game.
"We're going to miss him, but at the same time it's an opportunity for other guys to be involved in bigger roles," Ruff said Saturday.
The Sabres, with eight defensemen already on their active roster, will put 22-year-old rookie Chris Butler into Sekera's slot. Butler has been steady since the Sabres called him up from Portland of the AHL in December, and is a plus-3 in 11 games.
Butler was promoted when captain Craig Rivet was sidelined because of a shoulder injury.