CALGARY - Calgary Stampeders linebacker Juwan Simpson has been sidelined four to six weeks with a broken clavicle.

The CFL club made the announcement Monday via Twitter.

Simpson has started at middle linebacker for the Stampeders every game since the 2012 season-opener.

The three-time West Division all-star and Stampeder co-captain has 27 tackles and a pair of sacks in 12 games this season. Simpson has been a Stampeder for eight seasons and won Grey Cups with the team in 2008 and 2014.

Calgary added defensive backs Brandon McDonald and Keith Lewis to the roster and placed cornerback Joe Burnett on the six-game injured list Monday.

Burnett suffered an ankle injury on a punt return during Friday's 25-23 win over the Blue Bombers in Winnipeg. He was filling in for injured Tim Brown on return duties.

McDonald was added to the active roster, while Lewis was placed on Calgary's practice roster.

McDonald had 33 tackles, two interceptions and three knockdowns in eight games this season for the Ottawa Redblacks before his release Aug. 26. He appeared in a pair of games with the Stampeders in 2014 and totalled three tackles.

The 30-year-old also played a combined 80 games in the NFL for Cleveland, Arizona, Detroit and Tampa Bay.

Lewis, who played two seasons for Virginia University of Lynchburg, attended training camp of the New York Jets this season and Tampa Bay's in 2014.

Calgary also released offensive lineman Nate Menkin from the practice roster.