Everton full-back Leighton Baines is to miss the final two Premier League matches of the season after undergoing ankle surgery.
The former Wigan Athletic man limped off injured during last weekend's 2-0 defeat to Sunderland at Goodison Park.
It was confirmed earlier this week that Baines would see a specialist to determine the extent of the injury.
And manager Roberto Martinez confirmed ahead of the trip to West Ham that Baines struggled with the issue for the past three years and has undergone a procedure to correct the problem.
"Leighton had a bit of instability in his ankle that flared up and it was painful in the last game," Martinez said. "It needed repair work so he had surgery on Wednesday.
"It was a straightforward operation to clear the ankle and give it stability. He'll be out until the start of pre-season, but it's what he needed, he was trying to play through the pain barrier.
"It's been a problem since 2012, it's been showing signs it needed work. He saw the specialist yesterday and we're looking forward to getting him back.
"It's a situation where it doesn't affect you for a period then you get a knock and it flares up, that's what happened. It was quite difficult for him to play pain free, the advice from the specialist is to treat it well and make sure the ankle is perfect going forward.
"We look forward to seeing Leighton with a period of getting fresh and getting ready for the next campaign. The way Leighton is, he doesn't want to miss playing and always puts himself forward to play.
"When you're not pain free it can be difficult and it was evident against Sunderland."
Baines' injury looks set to sideline him for England's friendly against Republic of Ireland, and the Euro 2016 qualifying fixture in Slovenia next month.
