Arteta suffers recovery setback
The 27-year-old Spanish midfielder, who ruptured a cruciate knee ligament injury in February, has had a procedure to remove an infection from the same knee and is now recovering.
"Mikel has needed to have a 'wash out' on his knee after doctors found an infection," Everton manager David Moyes was quoted as saying on Wednesday.
"It is a setback for him. However we can't say how long it has put him back."