Chris Wilcox could miss a month with a thumb injury

The Celtics will enter their critical four-game road trip beginning Tuesday with just 11 active players, as once again keeping their centers healthy remains difficult.

At practice Sunday, coach Doc Rivers revealed that Chris Wilcox will miss perhaps a month with a sprained ulnar collateral ligament in his right thumb, sustained in Tuesday’s loss to the Chicago Bulls.

Wilcox attended the team’s Christmas party for local children with a brace on his right hand. With his absence, the Celtics have one true center on the roster — Jason Collins — despite having addressed the position in the offseason.

President of basketball operations Danny Ainge re-signed Wilcox and added Darko Milicic and Collins, and drafted Syracuse’s Fab Melo for support. Milicic left the team after less than a month to be with his ill mother in Serbia and Melo is playing for Maine of the NBA Development League.

– Reported by Gary Washburn of the Boston Globe