IRVING — The wait for Dallas Cowboys defensive end Anthony Spencer to return from preseason knee surgery is over. He is out for the remainder of the season.Owner Jerry Jones announced Tuesday on his radio show that Spencer needs season-ending and potentially career-threatening microfracture surgery on his left knee.The Cowboys used their franchise tag, with a one-year guaranteed salary of $10.6 million, on Spencer in the off-season. He will become a free agent at the end of this season.Agent Jordan Woy said Spencer should be 100 percent by January or February, according to doctors.He is OK. Disappointed, but ready to get back next season, Woy said.The seven-year veteran has been trying to recover from arthroscopic knee surgery in July. But loose cartilage remained a problem, he said last week, and bone was still making contact with bone.Spencer, who missed the entire preseason and the season opener against the New York Giants, suffered a setback in his recovery after playing 34 snaps against Kansas City in Week 2 after a limited practice week.Spencer missed two games last season with a shoulder injury. He still had a career-best 11 sacks and made 106 tackles.George Selvie, who has two sacks in three games this season, will continue to start at left defensive end. Caesar Rayford, who has worked at defensive tackle since he was acquired from Indianapolis, will move back to end and compete for snaps with Edgar Jones.Ratliff improvingWith defensive end Anthony Spencer out, the return of defensive tackle Jay Ratliff is even more vital to the Cowboys this season.Ratliff was placed on injured reserved/designated to return at the start of the season because of lingering hamstring and groin injuries. Three weeks are down and Ratliff should be back in three more weeks, possibly in time for the Oct. 20 game against the Philadelphia Eagles.Jason Garrett said Ratliffs rehab is going well.He is halfway through it, Garrett said. We feel like he is making progress and hopefully he will be back here in a few weeks. More roster movesThe Cowboys signed former LSU defensive tackle Drake Nevis and released defensive tackle Jerome Long on Tuesday. Nevis worked out with the team last week. Long appeared in the first three games, but had no stats. He was in on 27 plays Sunday against the St. Louis Rams.