Robert Griffin III's recovery from knee surgery has been "unbelievable," Dr. James Andrews told ESPN's Stephania Bell on Friday.

"I've been real mum on talking too much about RG III. He wants his recovery to be fairly private, but I can tell you he's way ahead of schedule. His recovery has been unbelievable so far," Andrews told ESPN.

"RG III is one those superhumans. First patient I ever had like that was Bo Jackson. And recently I, of course, had Adrian Peterson, who is also superhuman. They have an unbelievable ability to recover, where as a normal human being may not be able to recover."

Andrews, who performed surgery to repair two of Griffin's knee ligaments on Jan. 9, was speaking to ESPN for an upcoming feature story on South Carolina running back Marcus Lattimore, who is rehabbing with Griffin to prepare for the NFL draft after also having knee surgery.

Griffin suffered a sprained LCL in Washington's Week 14 win against the Baltimore Ravens, but returned two games later. He then tore his LCL and ACL in a first-round playoff loss to the Seattle Seahawks.

At the NFL's owners meetings last week, coach Mike Shanahan wouldn't put a timetable on Griffin's recovery.

"For me to tell you anything at this time is kind of ludicrous," Shanahan said Thursday. "All I can tell you, though, is when you've got a guy who's got the flexibility that he has, he's got the strength, he's got the desire to be the best at what he does, usually good things happen.

"He's in there every day. He's working out six, eight hours a day. He's got great strength and great flexibility, and that gives him a chance to hopefully be ready for the season, right? I don't know."

Griffin won The Associated Press 2012 NFL Offensive Rookie of the Year award after setting the NFL record for best passer rating by a rookie quarterback and leading Washington to its first NFC East title in 13 years.

Information from The Associated Press was used in this report.