METAIRIE, La. -- Saints linebacker Jonathan Vilma has travelled to Philadelphia to have arthroscopic knee surgery, but how long he'll be sidelined remains unclear, coach Sean Payton said Thursday night.
"We'll have him back and we'll kind of go from there," Payton said.
The 31-year-old Vilma has had numerous surgeries on his left knee during the past two seasons. He missed five games in 2011 and started last season on the physically unable to perform list. However, Payton stopped short of saying he viewed Vilma's latest surgery as a setback.
"This is a little different procedure, so we'll how he does when he gets back," the coach said.
Vilma opened training camp working as a first-team middle linebacker in New Orleans' 3-4 defence, but had missed a handful of practices lately.
His absence will move veteran David Hawthorne, who was acquired as a free agent last season, up to the first team in advance of Friday night's preseason game against Oakland in the Superdome.
Payton portrayed Vilma's absence during preseason as an opportunity to better evaluate other linebackers before coaches have to decide who to cut and who to keep as current 90-player roster is trimmed to 53 by the start of the regular season.
"The most important thing is getting the chance to evaluate all these players," Payton said. "A guy like Jon Vilma, I know exactly what we have in that player. It gives us a chance to see not only Hawthorne more, but then if he's going earlier, the guys behind him are getting to play quicker, too."
The 28-year-old Hawthorne started 10 games last season but was hampered by left knee and right hamstring injuries and said he is eager to show he can provide more support to his unit than he did a year ago.
"I came here to play football and then when you get sidelined by injury after injury, it kind of gets you down, you know. You don't really know your place," Hawthorne said. "That's kind of all behind me and I'm feeling good and I'm feeling healthy."
Meanwhile, Curtis Lofton, the strong side middle linebacker, was absent from practice Thursday and Payton did not offer an explanation for that. Lofton practiced Wednesday without showing any apparent limitations.
Ramon Humber worked in Lofton's spot Thursday and sounded as if he expected more playing time against Oakland.
"I definitely feel comfortable," Hawthorne said. "As a linebacker, you kind of have to learn the whole defensive system. You have to know what everybody is doing because you're the quarterback of the defence."