ALLEN PARK — It was day 15 of Lions’ training camp and the casualties continue to mount, although none appear serious.

Jeff Backus, who rarely misses a day of practice and never misses a game (he has 175 straight starts), sat out on Tuesday. Coach Jim Schwartz said it was a tight back. Backus has a broken thumb but has been playing through that. Tuesday it was mostly Jason Fox and Corey Hilliard taking reps at left tackle.

Defensive tackle Corey Williams sat out today, joining Sammie Hill (back) who has missed three days. Linebacker Stephen Tulloch also was sidelined.

Calvin Johnson, who got a day of rest on Monday, was back at work. So was WR Ryan Broyles who is fighting soreness in his knee following ACL surgery six months ago. Rookie Patrick Edwards (calf) also returned after missing two days.

Still out were Kyle Vanden Bosch (back), Louis Delmas (knee), Mikel Leshoure (hamstring), Jahvid Best (concussion) and Jonathan Scott (knee).