Lady Gaga has had to postpone four show because of an injury that left her unable to walk, leaving the pop singer "heartsick" after making the decision.

A news release on Tuesday night said the pop star's performances set for February 13 and 14 in Chicago, February 16 in Detroit and February 17 in Hamilton, Ontario, Canada, had been postponed.

She is suffering from synovitis, a severe joint inflammation.

She took to Twitter to explain, saying she injured herself during a performance some time ago and her condition had worsened.

"I've been hiding a show injury and chronic pain for sometime now,over the past month it has worsened," Gaga tweeted. "I've been praying it would heal." She continued: "I hid it from my staff, I didn't want to disappoint my amazing fans. However after last nights performance I could not walk and still can't."

Gaga is hoping to resume her Born This Way Ball Tour next Tuesday in Philadelphia.

"To the fans in Chicago Detroit & Hamilton I hope you can forgive me, as it is nearly impossible for me to forgive myself. Im devasted & sad," she continued to tweet, adding, "It will hopefully heal as soon as possible, I hate this. I hate this so much. I love you and Im sorry."