After a show in Amsterdam he tweeted: "Can you limit what gets thrown on stage please! Coz somethin thrown at me tonight! Hit my knee! A lot of pain from it!"
He added: "Never wana sound like I'm complaining! But only having my operation 5 months ago, I still get a bit of pain and I'm very scared about it".
Overall though he thanked the Dutch city for "a great couple of shows".