One Direction star Niall Horan has given a progress report on the state of his knees.

The Irishman recently underwent an operation on his troublesome knees, which regularly flare up.

He admitted on Twitter that the surgery was much larger in scale than initially thought.

Speaking to a fan on the social networking yesterday (January 21), the singer said that whilst he is still "sore" from the operation, he is on the mend.

Horan said: "Knees good! Sore but gettin there!"

The Irishman also said on Twitter that One Direction have the "best fans ever" after seeing a video of numerous devotees in Finland walking together with banners displaying the band's name.

He said: "Our manager just sent this to me! holy shit! This is part of the reason why I say to you guys all the time that we have the best fans ever."