From her site:
Born This Way Ball Tour Cancellation
Thursday, 12 February 2013 – For immediate release. Live Nation Global Touring has confirmed that the remainder of the Lady Gaga Born This Way Ball performances have been cancelled. After additional tests this morning to review the severity of the issue, it has been determined that Lady Gaga has a labral tear of the right hip caused by strenuous repetitive movements in her performances. She will need surgery to repair the problem, followed by strict down time to recover. This unfortunately, will force her to cancel the tour, so she can heal. Refunds for the cancelled performances will be available at point of purchase starting Feb 14, 2013.
If you’d prefer to read the info. on her site, it can be found at: https://littlemonsters.com/post/511c2006eb8114f40f0001e7