ARCADIA, Calif.- Premier Pegasus, the early morning-line favorite in Saturday&rsquo;s Santa Anita Derby before being sidelined on Thursday because of a hairline fracture in the cannon bone of his left foreleg, underwent surgery to stabilize the injury on Friday.\r\nPremier Pegasus will be reevaluated again in 90 days, according to Maria Ayala, the assistant to owner-trainer Myung Kwon Cho. Ayala said one screw was inserted to stabilize the affected area, which she said was on the outside of the cannon bone. The injury will keep Premier Pegasus out of training for several months.\r\nThe operation was conducted at an equine hospital on Santa Anita&rsquo;s backstretch. Premier Pegasus was back at Cho&rsquo;s barn at Santa Anita by 4:20 p.m., a little less than four hours after the surgery. He quickly began eating when returned to his stall.\r\n&ldquo;The doctor said it was good, that the hairline is small,&rdquo; Ayala said. &ldquo;In 90 days, there will be more X-rays and we&rsquo;ll see.&rdquo;\r\nThe injury was diagnosed after Premier Pegasus galloped on Santa Anita&rsquo;s infield training track on Thursday morning.\r\nPremier Pegasus has won 4 of 5 starts and $293,400. He has won three stakes, including the Grade 2 San Felipe Stakes by 7 3-4 lengths over 1 1-16 miles on March 12, a performance that pushed him to the fore of the California 3-year-old division.