She took to Twitter about midday Friday to announce the injury, which took place Thursday.
But she was right back at rehearsing later Friday, despite the news.
Had rehearsal today.. it's tough dancing with a broken rib. @iamvalc choreographed an amazing routine- fingers crossed I can pull it off! :/— Danica McKellar (@danicamckellar) April 26, 2014
McKellar is next set to dance in Monday night's episode of the television series. She scored a 36 out of a possible 40 during last week's performance.