(Reuters) – Britain’s former junior Wimbledon champion and Olympic mixed doubles silver medallist Laura Robson announced her retirement on Monday due to persistent injury problems. A former world number 27, Robson lifted the junior crown at the grasscourt Grand Slam as a 14-year-old in 2008 and followed up her success with an Olympic medal partnering Andy Murray at London 2012. The 28-year-old, who made the fourth round at the U.S. Open in 2012 and Wimbledon the following year, had a wrist operation in 2014 ago before three hip surgeries derailed her career. She was last in action at an ITF to…