The injury was reportedly sustained during the Seahawks' Week 3 win over the Denver Broncos. Okung has started both of Seattle's games since then and is attempting to play through the pain, according to the report.
Okung started eight games for the Super Bowl-winning Seahawks last season, spending half the season on injured reserve with a torn ligament in his toe.
In 2012, Okung was named to the Pro Bowl after starting a career-high 15 games for Seattle. His 2011 season was cut short due to a torn right pectoral muscle and he sprained both ankles in 2010, missing six games.
Seattle drafted Okung with the sixth-overall pick in the 2010 NFL Draft after he spent three years at Oklahoma State.
The Seahawks are also dealing with injuries to starting center Max Unger, who missed Sunday's game with a sprained foot, and tight end Zach Miller, who remains out after having ankle surgery.
The Seahawks are 3-2 this season after losing to Dallas on Sunday. It was only Seattle's second loss at home since 2011.
Seattle plays the Rams in St. Louis in Week 6.
- Molly Geary