Lady Gaga has cancelled her remaining US tour dates due to a hip injury.
Live Nation Global Touring say in a news release that Lady Gaga has a tear in her right hip that will require surgery, followed by a recovery period.
The pop star had 21 dates through March 20 remaining on her Born This Way Ball tour schedule, including shows in New York's Madison Square Garden.
Fans who have already bought tickets will receive a refund starting today.
Lady Gaga postponed four dates on Tuesday after experiencing difficulties Monday during her concert in Montreal. The singer’s show is high energy with non-stop dancing. She explained to fans on Twitter that she’d hurt herself while performing some time ago.
She wrote: "I hid it from my staff, I didn’t want to disappoint my amazing fans. However after last night’s performance I could not walk and still can’t."
Gaga has not tweeted since.
A message on the singer's website says a doctor has ordered her to postpone the shows due to synovitis, a severe inflamation of the joints.
However, she underwent tests yesterday morning that showed she had a labral tear in her right hip.
The labrum is a layer of muscle that helps holds the ball-shaped hip joint in place. The news release says the surgery will require strict downtime.
The tour, in support of her second album Born This Way, began last April in Asia and was one of 2012’s highest grossing.
Pollstar reported the tour made more than $US161 million ($A156.49 million) in 2012 with an average attendance of more than 31,000, making it the fifth-highest grossing tour.