MÖTLEY CRÜE guitarist Mick Mars was knocked over by a fan on stage during the band's headlining concert last night (Saturday, May 4) at Spectra Place in Estevan, Saskatchewan, Canada.As the group was performing the song "Primal Scream", an audience member rushed the stage, bumping into Mars and grabbing MÖTLEY CRÜE singer Vince Neil before being tackled and hauled off. "What the fuck is wrong with you, you fucking idiot?" drummer Tommy Lee shouted as the man was being dragged off the stage. Neil then told the audience, "We might be back," before he and his MÖTLEY CRÜE bandmates disappeared from view. They later returned to close out the set. Fan-filmed video footage of the incident can be seen below. Mars, who was diagnosed with ankylosing spondylitis (AS) when he was 19, turned 62 years old yesterday. In a 2008 interview with MusicRadar, Mick stated about his medical condition: "It's no walk in the park. In fact, it's why I kind of walk like Frankenstein. [laughs] The thing about ankylosing spondylitis is, it's caused by a gene; you first start noticing pain in your hips, usually when you're in your teens. What it does is it slowly fuses your bones together — your spine, your ribs… With most people it stops in their 30s, when the disease is still in their lower back. In my case, I have a rare form of the disease that hasn't stopped, so it's all the way up my whole back and into my brain stem. It's literally squeezing my rib cage together, so I've lost some height. And now that it's up in my brain stem it's hard for me to move my head in any direction, be it up and down or sideways. So I can't drive, I can't do any of that kind of stuff — this isn't a 'boo-hoo', it's just the facts." He added: "There's no cure, but the doctors say they might, might be able to chip away some of the bone growth at the brain stem; it'll still grow back but I'll take any improvement. If I could just move my head a little and stand up straight, I'd be a happy man." MÖTLEY CRÜE kicked off the most expansive run of Canada in the band's history on April 21 in Penticton, British Columbia. The CRÜE will return to The Joint at Hard Rock Hotel & Casino in Las Vegas for a dozen shows September 18 through October 6.