Johnson was carted off the practice field and taken away in an ambulance after suffering the injury and will have surgery next week.
Johnson, 26, was drafted by the team in the 3rd round of the 2010 draft.
Johnson saw action in all 16 games last season and had one start. Johnson had been getting first-team reps during practice at the position and was a leading candidate to replace Tyson Clabo, who was released in the offseason. Lamar Holmes, who is in his second-year, was the backup and will likely get an opportunity at the starting nod.