Actress Angela Lansbury (search) will undergo knee replacement surgery Thursday, her daughter said Tuesday. "Her knee is so painful from years of dancing," said Deirdre Battarra, 52.

Lansbury, who rose to fame on Broadway and starred in television show "Murder, She Wrote (search)," tripped over an electrical cord Friday night while joining celebrities onstage for Stephen Sondheim's 75th-birthday concert at the Hollywood Bowl.

But the slip had nothing to do with Lansbury's surgery plans, said Battarra, who expects her 79-year-old mother to take one or two months to recover.

"She's pretty at ease about it all," Battarra said.