Croatia's veteran ski champion Ivica Kostelic on Tuesday underwent another operation on his troubled right knee in a Swiss clinic, the national ski association said. The 33-year-old Kostelic underwent succesful surgery in a Basel clinic during which doctors "treated his meniscus and removed bone growths," the association said in a statement. It was the 11th time the Zagreb-born Kostelic had gone under the knife to repair damage to his knees -- 10 times on the right one -- caused by years of wear and tear on the slopes, especially in his preferred slalom discipline.