ENGLEWOOD, Colo. -- Wednesday afternoon, the Broncos confirmed that center J.D. Walton underwent an additional procedure on his injured left ankle this week.

Walton, who missed all but the first four games of the 2012 season with the ankle injury, is expected to be out until mid-October.

In the meantime, seventh-year lineman Manny Ramirez worked at center throughout offseason practices and appears to be the immediate replacement currently on the roster.

But don't be surprised if the Broncos also look to free agency to fill the void, namely bringing back free agent center Dan Koppen.

The NFL's all-time winningest offensive lineman started 13 games -- including postseason -- for the team last year after Walton injured his ankle. He could fill that same role in 2013, which would be his 11th season in the NFL.

Looking over the roster for other centers, last year's fourth-round pick Phillip Blake started 26 games at center at Baylor University, but was placed on injured reserve with a thumb injury last September after being inactive for the team's first two games.

C.J. Davis, who matched a career high with seven regular-season appearances in 2012, is listed as a center/guard on the team's official roster, and Quentin Saulsberry, who spent last year on the club's practice squad, is the club's only other lineman listed solely as a center.

The Broncos' bye week in 2013 falls in Week 9 -- Sunday, Nov. 3. So if Walton's timetable pinpoints a mid-October recovery, a return to the field following the bye week doesn't appear to be out of the question.

Koppen and Ramirez could be the top options until then.