The 33-year-old initially suffered the setback while on international duty with the Republic of Ireland at Euro 2012.
Having undergone two operations to try and rectify the problem, Dunne has finally been given the green light to step up his fitness work.
However, Villa boss Paul Lambert is unsure when Dunne, signed from Manchester City in a £6 million deal four years ago, will be ready for a first team recall.
He said: "Richard is back in training and it's his first time since the European Championships really.
"Will he be back soon? I'm not sure really because he's got to get up to speed with training and get some games under his belt.
"He's still a wee bit away."
Dunne has endured a difficult year with injuries and missed the final three months of last season with a broken shoulder.
But he insisted: "The last operation I had seems to have really worked.
"I've been lucky not to have too many injuries during my career but it's been several months where I've not been fit."