One Direction's Irish heartthrob Niall Horan has told his Twitter followers that he wants to get knee surgery after the band's upcoming world tour.

In a series of posts on the social networking site (October 4), he explained that after tearing his meniscus a couple of years ago the injury has progressively worsened and he's now walking around on crutches because it's so painful:

"I always had a bad knee, added to it playin ball the other day! Its messed up now! Operation time. I'm on crutches hahahahhaa! Funny as hell."

He added in reply to a fan that he put more stress on his knee by having a kick around with friends: "Was playin football and did ligaments."

When asked if he has scheduled an operation, Horan wrote: "Whenever I have time, coz I need about 2.5 months for rehab for it! it won't be until end of world tour I'd imagine."