Lady Gaga has postponed her world tour after sustaining an injury which she says has left her unable to walk. 
 
 The singer has severe inflammation of the joints, known as synovitis. 
 
 Writing on Twitter, Gaga apologised to fans, saying she was "devastated" at having to delay several shows in America and Canada. 
 
 "I've been hiding a show injury and chronic pain for sometime now," she wrote. "However, after last night's performance, I could not walk." 
 
 'I'm sorry' 
 
 "To the fans in Chicago, Detroit & Hamilton. I hope you can forgive me, as it is nearly impossible for me to forgive myself. I'm devastated & sad," she tweeted. 
 
 Continue reading the main story It will hopefully heal as soon as possible, I hate this. I hate this so much. I love you and I'm sorry Lady Gaga 
 
 "It will hopefully heal as soon as possible, I hate this. I hate this so much. I love you and I'm sorry." 
 
 Performances on 13 and 14 February in Chicago and 16 February in Detroit will now be rescheduled. She has also postponed a concert in Canada on 17 February in Hamilton, Ontario. 
 
 The new dates for these shows are yet to be announced. 
 
 It is thought the pop star will be well enough to perform again in Philadelphia on 19 February. 
 
 Follow @BBCNewsbeat on Twitter 

 Lady Gaga has been forced to postpone several shows due to severe joint inflammation. 
 
 “There’s an unfortunate announcement coming out right now, concerning myself and the Born This Ball. Im so sorry. I barely know what to say,” Lady Gaga wrote, the first of many Tweets on Tuesday about her medical condition. 
 
 “I’ve been hiding a show injury and chronic pain for sometime now, over the past month it has worsened. 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 apologized to her fans for having to postpone her gigs. 
 
 “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 wrote. “It will hopefully heal as soon as possible, I hate this. I hate this so much. I love you and Im sorry.” 
 
 Later, another Tweet was posted on Gaga’s account further explaining her medical condition. 
 
 “Due to a case of synovitis, (severe inflammation of joints) Gaga’s doctor has ordered her to postpone show[s] in Chicago, Detroit + Hamilton,” a Tweet on Tuesday evening read. 
 
 -- Jolie Lash
– Lady Gaga is postponing three performances because she's suffering from synovitis, or "severe inflammation of the joints," according to her Twitter account. She's delaying shows in Chicago, Detroit, and Hamilton, Ontario, the BBC reports. "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 (sic) & sad," she tweeted, per Access Hollywood. "I’ve been hiding a show injury and chronic pain for sometime now, over the past month it has worsened ... 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." A performance in Philadelphia Feb. 19 is set to go on as planned, the BBC notes.