The Rangers' captain fell on his left shoulder while scuffling with Philadelphia's Maxime Talbot in the third period of Tuesday's 2-1 win over the Flyers.
At first there was concern Callahan had a separated shoulder and could miss significant playing time, but the team said a magnetic resonance imaging exam revealed a less serious subluxation, the team said.
The right wing had scored the eventual winning goal in the second period of Tuesday's contest.
Callahan could return to action as early as Feb. 10 against the Tampa Bay Lightning at Madison Square Garden, the New York Daily News said. If he misses 14 days, he would not return until Feb. 14, when the Rangers host the Islanders.