Bolton midfielder Joey O'Brien is expected to be on the sidelines for around eight weeks following an operation on his left knee.

O'Brien has started rehabilitation after visiting renowned surgeon Dr Richard Steadman in Colorado last Friday for surgery over the weekend to clean out the joint.

O'Brien and Bolton's medical team are pleased with the outcome, and it is hoped the Republic of Ireland international will again be available for selection towards the end of April.

Assistant manager Chris Evans said: "Everything went well. Richard Steadman is the leading specialist in his field and Joey has known him previously.

"The doctor was pleased with what he saw and the diagnosis was far better than had been feared."

It has been a wretched season to date for O'Brien who has only made eight appearances, with his last on October 18 in the goalless draw with Blackburn at the Reebok Stadium.

O'Brien initially sustained a hamstring injury before tearing a thigh muscle on his return to training but fortunately for the 23-year-old the current knee problem is not connected with the one which kept him out for the entire 2006-07 season.