Dunne has been side-lined since suffering the setback while on Euro 2012 duty for the Republic of Ireland and a trio of operations have failed to cure the problem.
Lambert would welcome the availability of the the former Manchester City player, whose contract runs out this summer.
But the Scot acknowledges it is not the sort of injury which allows the defender to play through the pain barrier.
Lambert said: "It's been really complicated that injury. Richard has been over to the United States a couple of times to try and get it sorted.
"But there are little niggles that aren't clearing up. That's a real frustrating thing for him.
"Is it career-threatening? No, nothing like that. You can't say that.
"Richard has been trying his utmost to get back fit. He's been to the best people (specialists) on the other side of the world.
"He feels good at some points, but not so good at other times. He can't play through the pain barrier with that injury."
Dunne has barely tasted any action for the past 12 months. He suffered a shoulder injury last February and only returned for the final two games of the 2011-2012 campaign.
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