Chicago Bears defensive lineman Terry "Tank" Johnson is recovering Friday from surgery to repair a torn quadriceps muscle, an injury that could sideline him for at least four months. The 24-year-old Johnson injured his leg during a workout and had surgery last week, the Bears said. He is expected to be out for four to six months, missing most of training camp. Johnson's agent, Bill Heck, declined to discuss specifics of the injury. The team said he was not working out at Halas Hall at the time. Johnson, who started several games last season, is considered a promising nose tackle.