One Direction star Niall Horan has taken to Twitter to address his recent knee surgery, telling fans it was "a complete success".

The Story Of My Life singer was forced to have surgery ahead of 1D's epic Where We Are stadium tour after dislocating his knee repeatedly since he was a child.

Hey guys I know most of you have seen those pics today! Yes I've had major knee surgery , a much larger surgery than first anticipated ,

— Niall Horan (@NiallOfficial) January 17, 2014

The Irish heartthrob was pictured by The Sun landing at Heathrow airport after his operation in the US, with the 20-year old seen hobbling on crutches.

Referencing the snaps in his tweets, Horan said: "Hey guys I know most of you have seen those pics today!

But i would like to tell u , it was a complete success ! Considering the scale of it! So all I ask of you guys is that you would respect my

— Niall Horan (@NiallOfficial) January 17, 2014

Privacy as I try to recover and get for the where we are tour!

— Niall Horan (@NiallOfficial) January 17, 2014

"Yes I've had major knee surgery, a much larger surgery than first anticipated. But i would like to tell u , it was a complete success ! Considering the scale of it!"

He went on to add: "So all I ask of you guys is that you would respect my privacy as I try to recover and get for the Where We Are tour!"

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