1D's Niall Horan set to undergo knee surgery

Niall Horan is set to undergo knee surgery in the U.S. this week.

The One Direction star, who dislocated his knee as a child, has been troubled by it during the group's shows, Contactmusic reported.

Sources have revealed that Horan had physiotherapy sessions for years but the pain persisted, so surgery is the best solution for him to be fully fit and get him ready for a long tour.