Cornerback Leodis McKelvin is out indefinitely with a broken bone in his leg, while safety Donte Whitner had surgery Monday to repair an injured thumb, leaving the Buffalo Bills’ limping defense minus two more starters.

Coach Dick Jauron said McKelvin’s injury is the most serious and he isn’t sure when the player will return after he was hurt in the first half of a 27-7 loss to New Orleans on Sunday. Jauron said Whitner’s status will be monitored on a weekly basis, though the coach did not reveal the exact nature of the injury.

It’s not clear how or when McKelvin was hurt, though he was taken to the medical room to have tests in the second quarter. Whitner was hurt in the second half.

That means a defense already missing starting middle linebacker Paul Posluszny (broken left arm), will be further depleted on Sunday when Buffalo (1-2) travels to play at Miami (0-3). Posluszny is expected to miss a few more weeks after getting hurt in a season-opening 25-24 loss at New England.

“We’ve got some big losses on defense right now,” defensive tackle Marcus Stroud said. “But the thing is, we’ve got to be able to continue to keep plugging and get some other guys to step up and just keep playing. We can’t just throw in the towel.”

Veteran Drayton Florence, who was signed in free agency this offseason, is expected to take over for McKelvin. Florence made his Bills debut against the Saints after missing more than a month with a knee injury.

Rookie safety Jairus Byrd is expected to fill in for Whitner.

Jauron provided little update on the status of safety Bryan Scott (ankle) and starting left tackle Demetrius Bell (groin), who also were hurt against the Saints.

Jauron said Scott was having tests on Monday. Bell’s status will be monitored once the team returns to practice Wednesday.

Bell’s injury has the potential of further depleting an already young offensive line that has gone through several shakeups this month. Buffalo has lost starting right tackle Brad Butler, who was placed on injured reserve last week with a right knee injury. Bell opened the season as a first-time starter after Buffalo released veteran Langston Walker.