Billy Ray Cyrus will undergo knee surgery Friday (Sept. 7) in Nashville, but the operation won’t keep him off the set of Doc, his TV series. The singer’s knee damage stems from years of stage and sports activity, according to a news release. He may need crutches or a brace, but Cyrus expects to be in Toronto Monday (Sept. 10) to begin work on the show, which airs on the PAX cable channel. 09/07/01