The Chargers offensive line can use all the experienced depth it can get.

On Tuesday, a 52-game starting center was added.

J.D. Walton, 28, was signed to the roster. He made 16 starts last season for the Giants. He also has familiarity with Chargers coach Mike McCoy, as his other 36 starts came in Denver from 2010 to 2012 with McCoy the offensive coordinator. He and rookie tackle Tyreek Burwell, promoted from the practice squad, help fortify an offensive line that was hammered by injury Sunday.

In the first quarter, center Chris Watt aggravated a groin injury he incurred one week earlier in Cincinnati. He did not return and, at best, figures to be a game-time decision Sunday against the Browns. Center-guard Trevor Robinson likely would start in his place.

In the second quarter, left guard Orlando Franklin had his right ankle rolled upon when a Vikings defender fell into him. It took two assistants to escort Franklin from midfield to the sideline. He was carted off from there to the locker-room area and underwent X-rays, which showed he did not suffer a fracture, sources said.

Then, left tackle King Dunlap suffered a concussion in the fourth quarter.

None of the three starters returned.

The Chargers will hold their first practice of the week Wednesday. To what degree, if it all, the three will participate remains to be seen. Guard-tackles D.J. Fluker (ankle) and Chris Hairston (ankle) also are working themselves back.

Walton was in the Dolphins' training camp this summer before his Aug. 30 release.

A 2010 Broncos third-round pick, he spent 2011 and part of the 2012 season on the same starting line as Franklin. Walton suffered a season-ending ankle injury four games into 2012. It required multiple surgeries, the recovery carrying into 2013. He started that year on the Physically Unable to Perform List and, after being activated, didn't see the field until joining New York the following year.

San Diego created roster space earlier Tuesday for Burwell and Walton.

Guard Johnnie Troutman (forearm) was placed on injured reserve, and tight end Kyle Miller was waived.