West Ham defender Arthur Masuaku has had surgery "to help remove the pain that's been bothering me for nearly two years".
The DR Congo international missed Friday's 2-1 win at Leeds which lifted the Hammers up to fifth in the table.
After the game, manager David Moyes said Masuaku, 27, had undergone successful surgery on his right knee.
"It's been a very difficult decision to make," tweeted Masuaku, who has made 11 appearances in 2020-21, on Saturday.
"But for my good being and the rest of my career I have to make it."
West Ham midfielder Tomas Soucek dedicated the win against Leeds to the club's fans and Masuaku, adding on Twitter: "I keep my fingers crossed and wish you a quick return."
West Ham and Masuaku have not given an expected date for the player's return.
Masuaku joined the Hammers from Olympiakos in 2016 for £6.2m on an initial four-year contract.
In July 2019 he signed a contract extension until 2024.