Jockey Rosie Napravnik, who ranks in the top 10 nationally in wins and purse money won in 2011, was scheduled to have surgery Thursday afternoon at Christiana Hospital near Delaware Park to repair a broken left arm sustained in a spill at the track Wednesday afternoon.\r\nDuring the surgery, Napravnik, 23, was to have pins inserted to repair a dislocated ulna bone in her left forearm. Also, doctors were set to insert a new plate into her left wrist, which she fractured exactly four years ago in a spill at Colonial Downs. Napravnik told her publicity agent, Kelly Wietsma, that her radius bone snapped right where it meets the plate.\r\nIt has not yet been determined how long Napravnik will be sidelined. In 2007, when Napravnik broke her left wrist, she missed four months of action.\r\nWednesday, Napravnik was aboard Naseeb, the 5-2 second choice in a five-furlong turf race, when that 5-year-old mare broke down about a quarter-mile into the race. Napravnik was unseated and hit the firm turf course hard. Naseeb suffered a broken bone between her shoulder and elbow, according to her trainer, Dale Capuano, and was euthanized.\r\nNapravnik is the leading rider at Delaware Park with 36 wins from 146 mounts. Earlier this year, she became the first female jockey to win the Fair Grounds riding title.\r\nOverall, Napravnik was enjoying a sensational 2011 season, ranking eighth nationally in wins with 131 and ninth nationally in purse money won with $4,699,716. She won the Louisiana Derby aboard Pants On Fire, on whom she finished ninth in the Kentucky Derby, the best finish by a female rider in the world&rsquo;s most famous horse race.\r\nOn June 18, Pants On Fire, with Napravnik up, came back to win the Grade 3 Pegasus at Monmouth Park by two lengths and is being pointed to the $1 million Haskell Invitational at Monmouth on July 31.