Katy Perry is suffering from chronic knee pain.

The 'Roar' singer - who recently performed her ballad 'By the Grace of God' at the Grammy Awards - has revealed her constant performing has taken its toll on her body and she has resorted to multiple sessions of acupuncture each week in a desperate bid to save her knees.

She admitted: ''My knees are giving out on me now. I do acupuncture every two or three days.''

The singer-songwriter - who turned 30 last year - explained why she thinks her body is suffering, blaming it on her energetic stage performances which tire her out because they make her exercise like an Olympian.

She told The Sun newspaper: ''I tour with a stage that goes from the front of the house to the back of the house with a triangle thrust that is a moving treadmill, like I think I'm some kind of Olympic athlete.''

However, the state of her joints isn't the star's only worry, as she has been busy threatening to sue a New York company after they began producing figurines of the dancing sharks which accompanied her during her record breaking Super Bowl half-time performance.

Attorneys representing the 'Prism' maker sent a cease and desist letter to the 3D printing service Shapeways last week after it was discovered they were selling 6.9 centimetre models of the uncoordinated characters, with the company now halting production and offering customers refunds.