Cardinals lefthander Mark Mulder had surgery Monday to repair a left rotator cuff that failed to completely heal following surgery in 2006. Cardinals medical supervisor Dr. George Paletta performed the procedure in St. Louis. Paletta learned that Mulder's cuff had only half healed from the first surgery because of a "biological failure" of the area, Paletta said. Catcher Yadier Molina also had surgery Monday for removal of cartilage in his right knee. The club had known for about six weeks that Molina was suffering from a "small to moderate" tear and compared it to the condition that sidelined second baseman Adam Kennedy last month. Molina will resume baseball-related activities in three to four weeks and would be ready to play competitively in six weeks, Paletta said. Mulder could resume throwing in about three months and "start to throw off the mound before spring training," Paletta said.