Stewart was carted off the field after sustaining a left leg injury in Wednesday's practice, Ben Baby of ESPN.com reports.
Stewart was injured on the first day of training camp and is now on crutches and has his leg in a brace as he awaits the results of further testing following the injury. Stewart was the Bengals' first-round pick, at No. 17 overall, last year and appeared in just eight regular-season games due to ankle and knee injuries. His knee appeared to buckle in practice Wednesday. Stewart is expected to help replace the snaps vacated by Trey Hendrickson in Cincinnati this season.