McAdoo underwent surgery on Friday and is expected to miss the entire 2012 season.
McAdoo -- a 6-foot-7, 245-pound pass rusher -- was in the mix for a role with the Ravens this season after All-Pro linebacker Terrell Suggs partially tore his Achilles' tendon during a private workout in April.
This has to be a crushing blow for McAdoo, who hasn't played in competitive football in two years due to an NCAA suspension in 2010 and a knee injury that sent him to injured reserve last season.
On Wednesday, the 21 year old told the Ravens' official site how he felt like he was finally getting his feet under him after two years of frustration.
"I feel like I'm further ahead," he said. "There's always work to be done, but I feel like I'm better than I thought I was going to be."
Now McAdoo will be forced to start over again.
Follow Dan Hanzus on Twitter @danhanzus.