"There will be no doubt in my mind unless I get in a car accident or something," Greenway said Tuesday, according to 1500 ESPN Twin Cities. "From the knee perspective, it'll be 100 percent, good to go."
The 30-year-old linebacker underwent the procedure to address joint pain. A recent MRI test revealed some minor damage, and the Vikings decided the operation would be best done in June rather than risking an aggravation later in the season.
Greenway tore the anterior cruciate ligament in his left knee in his first exhibition game in 2006, an injury that wiped out his rookie year. He has not missed a game since.
He said Tuesday his most recent surgery isn't related to that earlier injury.
Greenway led the Vikings with 148 tackles last season, which ranked second overall in the NFL.
Information from The Associated Press was used in this report.