The 25-year-old Derby-born central defender is a summer signing following his release, for financial reasons, by Third Division Shrewsbury Town. The former Shrewsbury captain made more than 100 Football League appearances for the Shropshire club. A firm favourite among the Shrewsbury fans, he has also spent time with Derby, as a trainee, Chesterfield and Gresley Rovers, on loan. Tretton has signed a two-year contract with the Bulls.