Microfracture is a much more severe surgery than the arthroscopic knee surgery that Sharper was reported to have had. It is unclear whether Sharper will be available to the Saints this summer or how healthy he will be for the start of the season.
It also is a major reason why Sharper did not draw more interest on the free agent market. Sharper agreed to a one-year deal to return to the Saints on Monday.
When free agency started the first week in March, Sharper didn't take any visits. He made his first visit last week when he met with the Jacksonville Jaguars.
Sharper said in a text message to The Associated Press: "Just wanna tell you I'm extremely happy to be a Saint again. Now we can work on winning another world championship for the city of New Orleans."
The 34-year-old Sharper intercepted nine passes last season, returning three for touchdowns of 99, 97 and 42 yards. His total of 376 interception return yards set a new NFL single-season high, breaking the mark of 358 yards set by Baltimore's Ed Reed in 2004. Sharper leads all active NFL players in interceptions with 63, a career total that places him in a tie with Ronnie Lott for sixth on the all-time list. His 11 career interception returns for TDs ranks second to Rod Woodson's 12. Sharper's 1,412 career interception return yards ranks second to Woodson's 1,483.
Adam Schefter is ESPN's NFL Insider. Information from The Associated Press was used in this report.