St. Louis Rams running back Steven Jackson underwent back surgery last month, Jim Thomas of the St. Louis Post-Dispatch reports.

"It was a minor procedure," Rams head coach Steve Spagnuolo told the Post-Dispatch on Tuesday evening. "He feels great. It’s really not a big deal."

Jackson's surgery involved the removal of a herniated disc, and Spagnuolo added that Jackson will likely be held out of part the team's "Organized Team Activity" sessions, which include 14 sessions between May 18 and June 17.

The Rams also have a mini-camp which runs for June 10-12.

Despite Jackson undergoing surgery, the Rams did not do much to address the running back position this off-season.

Kenneth Darby, who finished second on the Rams with 152 yards rushing in 2009, remains on the roster, as does 2009 seventh-round pick Chris Ogbonnaya, who gained 50 yards on 11 carries last season. The Rams also signed undrafted free agents Keith Toston (Oklahoma State) and DeMaundrey Woolridge (Idaho, by way of Washington State) late last month.

The Rams have also kicked the tire on veteran running back Brian Westbrook, who was released by the Philadelphia Eagles this off-season. Westbrook is coming off multiple concussions, but has passed a physical with the Rams.