Stephen travelled to Colorado earlier in the week to consult with renowned surgeon Dr Richard Steadman on Wednesday.
He identified the problem and operated on the flying-full-back.
Stephen’s knee injury has troubled him since the middle of pre-season and has failed to respond to six weeks rest.
He now has to begin once again the long and torturous road towards rehabilitation.
He joins the long-term injured Gary Doherty, Goran Bunjevcevic, Stephen Clemence, Steffen Iversen, Chris Armstrong and Willem Korsten, who have all been operated on since the end of last season.
Stephen Carr is likely to be on the missing list for up to a further four months after his trip to America resulted in an operation to repair his long-standing knee injury.