Griffin was only partially active in previous practices this week after being held out of Sunday's 38-21 win over the Cleveland Browns -- the Redskins' fifth straight win.
Fellow rookie Kirk Cousins filled in for him and tossed for 329 yards and two touchdowns in his first NFL start, which elevated Washington into a three-way tie with Dallas and the New York Giants atop the NFC East.
Griffin told reporters his knee felt "really good" during the Wednesday workout.
"What doctors will do is they'll evaluate him tomorrow [Thursday], and hopefully there's no setback, no swelling with the knee," Redskins Coach Mike Shanahan added. "He'll be evaluated through the week, and if the doctors tell me the [ligament] is ready to go, I'll announce him as ready to go."