After undergoing surgery on Monday, Morgan is now in recuperation. He has not confirmed a return date, simply telling BBC Sport he will have to "wait and see what happens.I'm hoping I'll just be out for four months."
The 48-times-capped Wales fullback has just one year left on his contract with the Dragons and has suffered a series of major knee and ankle injuries which have blighted his career.
He last played for Wales against Japan in the 2007 Rugby World Cup but has not featured since Warren Gatland took over as Head Coach.
Morgan would have been keen to fight for a place in the Wales squad for the autumn internationals but those hopes have been dashed by his latest injury.
Dragons Physio Dan Martin said: "Kevin will undergo an intensive rehabilitation programme yet will likely not return until December 2008."