The Dane was withdrawn after 36 minutes of the Spurs game with a recurrence of his groin problem and is now expected to be out for around a month.
Despite the injury, Wenger has defended his decision to start the Dane in the North London derby.
"Bendtner is a big blow," he told arsenal.com. "I played him against Tottenham because he is strong in the air.
"It gives us more variety in our games because we can lose possession yet still win the next header with Bendtner.
"He makes us dangerous at set pieces and so we can change a little bit our game."