Gran Estreno, an 8-year-old horse who won multiple graded stakes after being claimed for $20,000 in May 2009, broke both sesamoids in his right front ankle joint at the end of a half-mile workout Monday morning at Fair Grounds. The horse has been shipped to the Rood and Riddle equine veterinary clinic near Lexington, Ky., and Dr. Larry Bramlage was scheduled to operate on the injured leg Friday. Gran Estreno can’t possibly race again, but if the surgery is successful he will be sound enough for mild farm life.