(Adds pope leaving hospital) By Alessandro Garofalo AOSTA, Italy, July 17 (Reuters) - Pope Benedict underwent minor surgery on Friday after the 82-year-old Roman Catholic leader slipped in the bath and broke his right wrist while on holiday in northern Italy. The Vatican said the operation, the first time the pope had to be treated in hospital since his election in 2005, lasted 20 minutes under local anaesthesia and that the pope would have to wear a cast for about a month. The pope, who is right-handed and uses his right hand to give his blessings, spent some seven hours in hospital and then returned to the mountain chalet where he is on holiday. He waved at well-wishers with his left hand as he left the hospital. It was not immediately clear if there would be lasting damage that might affect the pope's ability to play the piano. He is an accomplished pianist and usually relaxes in the evening by playing. Patrizio Polisca, the pope's personal doctor, stressed that the injury was caused by an accidental fall and that the pope was not feeling ill when he fell. He said pope had undergone osteosynthesis, a surgical procedure to stabilise and join the ends of fractured bones by mechanical devices such as metal plates, pins, rods, wires or screws. Polisca told reporters in the hospital in this northwestern Italian city he expected it would take about a month to heal but that the pope's vacation in the northern mountains near the border with France would continue as planned. "The Holy Father's overall condition is good," he said. Vatican spokesman Father Federico Lombardi told reporters earlier that the pope had slipped in his bath whereas Polisca's statement referred only to a fall in his residence. The German-born pontiff walked into hospital himself and the Vatican said that before being taken to hospital he celebrated mass and had breakfast in the mountain chalet. Tourists and visitors at the Vatican expressed concern about the pope's health. "Thank God it is nothing serious," Canadian Joey Shreider said. "I'm very sorry to hear the Holy Father is injured, we'll be praying for him that he makes a quick and speedy full recovery," said Irish archbishop Dermot Clifford, visiting the Holy See.(Writing by Philip Pullella, additional reporting by Philip Pullella, Silvia Aloisi and Stephen Brown; Editing by Elizabeth Fullerton))
