Obiang was injured in the 2-0 FA Cup loss at Wigan
West Ham midfielder Pedro Obiang is set to miss the rest of the season after an operation on his right knee.
The 25-year-old Spaniard was hurt in the FA Cup defeat at Wigan on 27 January.
Hammers' head of medical services Gary Lewin said: "We are confident that he will return fit and strong in ample time for pre-season."
West Ham are also missing striker Andy Carroll, sidelined for at least another two months after ankle surgery.
Obiang has played 86 games for the Hammers since arriving from Italian side Sampdoria in the summer of 2015.
Lewin said he was "delighted" with how the operation went after the midfielder suffered a tear to the medial collateral ligament.
"He went to a specialist in Barcelona for the operation and he is in the best possible hands as the rehab process gets under way," he said.
Source: bbc.com