Liza Minnelli, who broke her kneecap in a weekend fall in Italy, vowed she would perform at last night's Luciano Pavarotti-hosted benefit for Iraqi refugees — and she wasn't fooling. The 57-year-old entertainer sang live on Italian TV from her hospital room. She's scheduled to have surgery today. "I already have two fake hips. Now my right knee will need a metal screw," Minnelli joked to New York Post columnist Cindy Adams. "Somebody up there is trying to get me by the part!" Let's call this paranoia disguised as a joke.