The chronically ill musician, who suffers from a disease that makes it difficult for him to move, was knocked down by a person who also grabbed singer VInce Neil and struggled with security men.
Mars, who was celebrating his 62nd birthday, later reported his personal guard Rhyno had suffered two broken ribs.
Crue were performing their track Primal Scream when an audience member managed to evade stewards and climbed onto the stage. He ran straight into Mars, sending him to the ground, before making contact with Neil.
The show was stopped as techs restrained the attacker, with bassist Nikki Sixx looking on in concern – and apparently kicking the downed punter – as two roadies picked Mars off the floor and helped him walk off. Drummer Tommy Lee shouted: “What the fuck is wrong with you, you fucking idiot?” Neil told the crowd: “We might be back,” before disappearing. After a delay they returned and finished the show.
Mars was diagnosed with ankylosing spondylitis at the age of 19 – the incurable genetic condition causes the spine to fuse together, making it difficult to move.
Last year he told Classic Rock Revisited: “It’s one of those things that I call an inconvenience. I have days that are worse than others and there is always some amount of pain with my hips.
“There are some things that are not so cool, but there is one thing that is cool: I ended up bent. I can always see my guitar. If I’d been straight then I would not be able to see myself play.”
Yesterday he tweeted: “Thank all of you for your concerns about me being knocked down last night. I’m alright; nothing broken. My bodyguard Rhyno got two busted ribs.”
Crue bassist Nikki Sixx recently discussed Crue’s plans to split after a movie, a final album and a last world tour.