Zenner (chest) has been cleared to resume football activities, Tim Twentyman of the Lions' official site reports.
The Lions' ground game struggled to find its footing all season, but Zenner was beginning to make inroads in the offense before suffering cracked ribs and a partially collapsed lung from a brutal hit against the Bears in Week 6. Finishing his rookie season with 17 rushes for 60 yards (3.5 YPC) and two receptions (on three targets) for 11 yards, he displayed some acumen in multiple facets, which bodes well for his prospects in a backfield that may experience change under new general manager Bob Quinn.