Pedro Obiang suffered his injury at Wigan in the FA Cup. Robbie Jay Barratt - AMA/Getty ImagesWest Ham midfielder Pedro Obiang is expected to miss the rest of the season after a knee operation.
Obiang, 25, suffered medial ligament damage during West Ham's FA Cup defeat at Wigan on Jan. 27.
The news comes as a fresh blow to manager David Moyes, who was unable to add another holding midfielder to his squad in the window and is still dealing with a lengthy injury list.
West Ham head of medical Gary Lewin told the club's official website: "Pedro has undergone surgery to repair the medial collateral ligament, and we're delighted with how it went.
"He went to a specialist in Barcelona for the operation and he is in the best possible hands as the rehab process gets underway.
"Pedro is likely to be out for a little while, but we are confident that he will return fit and strong in ample time for preseason.''