The Browns issued a statement Thursday saying the running back, drafted No. 3 overall, had what the team termed "routine arthroscopic" surgery by Dr. James Andrews in Pensacola, Fla.
Sources told ESPN's Chris Mortensen on Wednesday the surgery would remove a "hang nail particle" of loose cartilage that was irritating Richardson's knee.
Richardson is expected to return before the regular-season opener, the sources told Mortensen. Another team source described the recovery as a "two-week deal."
A minor scope typically requires 3-4 weeks of recovery. Richardson slid a few spots in the RB rankings today to RB13. The Browns say they are "hopeful" Richardson will be ready for Week 1. Montario Hardesty looks set to start if Richardson misses time.