Umenyiora, 29 and in his ninth NFL season, is expected to be out 3-4 weeks after an arthroscopic procedure called a "simple debridement," Giants Vice President of Medical Services Ronnie Barnes said.
The defensive end recently ended a short holdout and reported to training camp but experienced swelling in his right knee after three days of practice, General Manager Jerry Reese said.
Umenyiora missed the 2008 season because of a torn knee ligament but tied for the team lead with 11.5 sacks last year. He has 60 sacks over his NFL career, all of which has been with the Giants.
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