Scalabrine was injured while going up for a rebound against teammate Patrick O'Bryant in practice on Tuesday, two days after he was hit in the head in the second half of a blowout win over the Dallas Mavericks.
Celtics coach Doc Rivers said Scalabrine didn't seem to be hit that hard in practice. But after trying to get to his feet, Scalabrine fell down and looked disoriented. The coach said he thought the problem was the hits coming so close together.
Rivers said Scalabrine won't return to practice until he's cleared by the trainers.