Report: Vikings center John Sullivan undergoes knee surgery

Pro Football Focus ranked John Sullivan the NFL's best center over the last two seasons. (US Presswire)

Minnesota Vikings All-Pro center John Sullivan underwent microfracture surgery on his left knee last week, 1500 ESPN in the Twin Cities reported.

Sullivan, who just completed his fifth NFL season, has quietly emerged as one of the top offensive linemen in the league. Pro Football Focus, a website that tracks and analyzes every gradable snap during an NFL season, has ranked Sullivan as the league's top center over the last two seasons. Sullivan's presence was instrumental in Adrian Peterson's 2,097-yard season. The Vikings ranked fourth on the NFL in rushes behind both guards and 10th on rushes up the middle, according to NFLGSIS.com.

Pro Football Focus ranked the Vikings' offensive line seventh out of 32 teams in run-blocking. Sullivan and offensive tackle Phil Loadholdt both received stellar grades from the site.

“In Sullivan and Loadholt they have two of the most punishing run-blockers in the league,” Khaled Elsayed of Pro Football Focus wrote.

Sullivan underwent the microfracture surgery at Dr. James Andrews' office in Pensacola, Fla., 1500 ESPN reported. The procedure is typically performed arthroscopically. A surgeon will insert “special instruments” into three small incisions in the knee to remove loose cartilage from an exposed bone.

Sullivan's recovery is expected to take three to four months. It typically takes two to six months for a patient's pain level in the knee to decrease, according to The Steadman Clinic, one of the nation's top orthopedic clinics. The gradual improvement is expected to occur over the course of two to three years.

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