The £6m summer signing from Ajax has been out of action since September due to a thigh injury.
The 25-year-old Dutchman now expects to be back in training at the end of the year.
He wrote on his official Facebook page: "I can slowly start building up strength again and start walking without crutches. Still a couple of months to go but I'm going to work hard and I'm sure I will get back stronger!"
Newcastle picked up their first win of the season on Saturday with a 1-0 victory at home to Leicester City.