The Dallas Cowboys just lost a tight end by placing James Hanna on the reserve/retired list as a knee problem is expected to cut his career short, the team confirmed Friday.A source tells SportsDay's Brandon George that lingering issues with the knee factored into his decision to call it a career.Hanna, a 2012 sixth-round pick by the Cowboys and a former Flower Mound standout, missed all of the 2016 season after undergoing knee surgery in August of that year.This coming season was the final one on his three-year, $8.25-million contract.