"It was pretty serious," he said. "You hear those words from a chiropractor and you start getting pretty scared. He said I needed to cut out all contact sport or it could be life threatening. That was it. Once he said that, it was out the door.
"It was pretty tough because I had been playing football since I was five and it was in my nature. He said I could still play touch, which I was stoked about because it meant I still had a football in my hand, and take up surfing because it helps with your posture."
Glenn not only stopped playing rugby league but he also stopping watching it because he would otherwise get too much of an urge to get back playing too soon.
Touch was at least an outlet and the he thinks it helped his game because it made him improve his footwork and ball-playing ability. In 2007 he was even named in the Australian under-20s national touch development squad.
Three years after his initial diagnosis, he was given the all-clear to play league again. The problem, however, was the fact he weighed little more than 70kg and was three years behind his peers in terms of physical development.
Quite incredibly, he made his NRL debut for the Broncos about three years later in 2009 and two years after that debuted for the Kiwis. In between, Glenn became the youngest ever Broncos captain, when aged 22, and also played an international for the Cook Islands.
He's still small for his position - he weighs 95kg when most of his peers are 5kg-10kg heavier - but he brings different attributes and in 2012 was the leading try-scoring forward in the NRL with 13.
"It was a fast road," Glenn admitted. "It's a road I never saw coming.
"Where I was mentally, I was so determined to try to make it as far as I could. I never thought I would make it to the NRL because I had missed out on three years and my body developing.
"I never expected to play in the NRL and to fulfil a childhood dream to put on a black and white jersey so, [while I'm disappointed not to be in the 17], I can't complain."
