Minnesota Vikings center John Sullivan will be sidelined for much of the offseason after he underwent microfracture surgery on his left knee last week.

Tom Pelissero of 1500 ESPN in the Twin Cities reports Sullivan has the surgery last Thursday and will require three to four months for rehabilitation. The goal is for Sullivan, who had a very strong season, to be fully ready to go by the start of training camp.

Sullivan was on the injury report for a knee issue just once during the 2012 season and he played at a high level anchoring a line that supported MVP running back Adrian Peterson.

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Brad Biggs covers the Bears for the Chicago Tribune