Lady Gaga, who cancelled her Born This Way Ball tour last week because of joint problems, says she's had surgery to fix her hip.

On late Wednesday, the 26-year-old singer posted a message on her blog thanking her fans for their support and saying she thought of them as she was wheeled into surgery.

“Thank You, Monsters, you really gave me a lot of strength today,” she wrote.

“Everything happened so fast, but when it came time to face it I reflected on the many stories and experiences you've shared with me about your lives. Meeting you backstage, reading your letters, watching you communicate with fans from around the globe to form a community that supports one another. You have completely blown my mind.”

Lady Gaga originally cancelled four dates on her tour, which began last April, after suffering from inflamed joints after a concert in Montreal.

After learning she would need surgery for a tear in her hip, she cancelled 20 dates. The singer, who gives a very vigorous performance including dancing, still faces a period of recovery.

Doctors say she has a labral tear in her right hip. The labrum is a layer of cartilage that helps holds the ball-shaped hip joint in place.

Lady Gaga said it had become painful to perform, but she was hiding the injury from her staff.