Larsen suffered a dislocated kneecap in Sunday's tie with the Giants, Ben Standig of The Athletic reports.
Larsen was seen wearing a leg brace and using crutches after the game, but the specifics of his injury were unknown at the time. This could be a season-ending issue for Larsen, although a timeline for his return has yet to be determined. With the Commanders now on a bye week, it's possible news of when he might be ready for return isn't divulged for some time.