When he was a young man, Motley Crue guitarist Mick Mars was diagnosed with ankylosing spondylitis (AS), a rare form of arthritis where the bones in the spine are fused together, causing chronic pain and immobility. But even though there's no cure for the condition, Mars has been able to find a positive side.

"I ended up bent," he told Goldmine. "I can always see my guitar.”

Mars wrote in the band's 2001 bestselling memoir The Dirt that he started having problems when he was 19. "My hips started hurting so bad every time I turned my body that it felt like someone was igniting fireworks in my bones. I didn’t have enough money to see a doctor, so I just kept hoping that I could do what I usually do: will it away, through the power of my mind. But it kept getting worse."

"Then, one afternoon while doing my laundry," he continued, "I started having trouble breathing. At first, it felt like someone had plunged a knife into my back. But as the weeks passed, the pain kept moving around my back. Next, my stomach started burning, and I worried that my whole body was about to fall apart. I thought that there was a hole in my stomach, and acids were leaking out and destroying my bones and organs. I’d grab hold of doorknobs, anchor my legs into the ground, and pull with my hands to stretch my back and ease the pressure out."

Although AS has negatively impacted his health, it also allowed him to take on the role of the silent, mysterious member of the band who focuses on the music, something with which he's quite comfortable, especially with the three larger-than-life personalities in Motley Crue.

“I don’t believe in my own hype," he said to Goldmine. "I don’t need to have a tremendously huge ego and I don’t need to thumb my nose at people. That, to me, is total bullshit. I am a guy who loves to write and play music, and that is what I have been doing.”

As Motley Crue's star rose, more symptoms turned up, including pain in his eyes whenever he looked at bright lights and a seizing of his lower spine, resulting in scoliosis and causing him to become three inches shorter than he was in high school.

The mid-'90s began a decade of turmoil for the band, beginning with the departure of singer Vince Neil, and his return in 1999 soon led to drummer Tommy Lee spending a few years away from the band. When bassist Nikki Sixx looked to get the original quartet back together in 2004, he had trouble getting in touch with his guitarist and chief collaborator and went to Mars' house fearing the worst.

"I was not only worried about writing music without a partner, but I had that gut-wrenching feeling that something was wrong," Sixx wrote in This Is Gonna Hurt. "What I saw haunts me to this day. A frail man of 80, maybe 90 pounds, shaved head, gray skin, with a beard to his chest. He was dying, addicted to painkillers, brought on by a disease called ankylosing spondylitis."

A successful hip replacement surgery was performed and the group got back together. But before Motley Crue could return to the road, Mars had to re-acquaint himself with his instrument.

“I kept getting worse and worse, and I just stopped playing guitar for almost two years," he told Metal Sludge in 2008. "Nowadays, it’s not so bad, but back then when I was high on all that stuff and Motley were having a break, I knew if I didn’t stop I was gonna die. In the end, I had to go to a neuro-psychiatrist to straighten me up and he said to me, ‘Just hold the guitar for an hour a day – don’t play it, just hold it.’ It was pretty bizarre but I got through it, and in the end I think I’m actually a better player because of it.”

Over the years Mars' AS has spread to his brain stem and affected his ability to move his head in any direction, making everyday tasks like driving impossible. And it caused a bit of a scare when a fan ran onstage and knocked him down during a concert in Saskatchewan, Canada on May 4, 2013 -- his 62nd birthday -- but he was unharmed, although his bodyguard sustained two broken ribs during the apprehension of the fan.

Shortly thereafter, Motley Crue announced that they would embark on one last tour, and both Neil and Lee cited Mars' health as one of the reasons why they were leaving the road. But Mars rebuked the claims, tweeting, "Once again, any rumors regarding a farewell tour due to my poor health is BS. I am doing fine, my AS has never kept me from touring. Thank all of you for knowing the truth ... When I'm done touring, you'll hear it from me."

Since his band's last show on New Year's Eve 2015, Mars has kept a low profile, resurfacing in June 2016 to play a few covers with Kenny Olson at an Ernie Ball event at a music industry convention. Around the same time, he was also involved in a project with singer John Corabi, who replaced Neil in Motley Crue in the mid-'90s, but even though Mars shared a taste of the music they were making, the collaboration didn't last. He insists his long-gestating debut solo album won't come out until he's 100% happy with it, and he promises that he's not going to let AS slow him down.

"It still hurts," he said in 2011."It still grinds now and then, but like I said, music is my whole passion. It's what I do. It's what I live for. I guess it keeps me alive. I'm just happy to be here, to be able to make people happy, to make people smile and give them what I feel inside from my music. I hope you like this, and if you don't, oh well."

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