FOXBOROUGH, Mass. -- Veteran defensive tackle Tommy Kelly, who left Sunday's loss to the Bengals with a right knee injury and didn't return, was not present for the start of practice Wednesday.

This highlights why the Patriots signed free-agent defensive tackle Andre Neblett on Wednesday, as depth is thin at the position, especially after the club lost veteran Vince Wilfork to a season-ending Achilles injury on Sept. 29.

After Sunday's game, Kelly said everything was good with the knee, and he walked out of the stadium under his own power and no noticeable limp.

After Kelly, the Patriots have rookies Joe Vellano and Chris Jones, along with Neblett, at defensive tackle.

Also at practice Wednesday, rookie defensive end Michael Buchanan and veteran running back Leon Washington (ankle) were not spotted.

Running back Stevan Ridley was back at practice after missing all of last week, and Sunday's game, with a knee injury.

Players were in shorts and light shoulder pads.