Rugby: Wallaby quits - head knocks left him staggering at the altar

Anthony Fainga'a - unconscious for more than a minute after a tackle against the USA during 2011 World Cup match in Wellington. Photo / Getty Images.

Wallaby Anthony Fainga'a had such severe concussion that he had to be held up at the altar during his twin's wedding.

And in one of the most brutal revelations of how head knocks can affect footballers, the 32-year-old former test back said he was one more incident away from becoming a "vegetable".

Fainga'a and his front rower brother were often on the field together for Australia, including at the 2011 World Cup. Anthony has announced his retirement and detailed the frightening reason why.

"I'm probably only one more head knock away from being a vegetable or not being able to play with my kids," the 23-test Fainga'a told Fox Sports News.

One of his worst moments came during the 2011 tournament, when he left the field after being unconscious for more than a minute. But it wasn't the worst or final knock he endured.

"After a couple of really big head knocks, I had to make a big decision," Fainga'a said.

"In 2016, my twin brother got married and at the altar, I was actually getting held up because of the head knocks.

"I received a couple of really big head knocks over my career and I was standing at the altar getting held up, I got walked out by someone.

"I got a few head knocks last year and after all these head knocks I had to make a decision, make a choice about what I wanted to do with my future.

"I love the rugby game so much but I needed to look after my mental health."

Saia and Anthony Fainga'a. Photo / Getty Images

Fainga'a continued to get offers to play and kept questioning whether he could continue. His family were reluctant to tell him to quit but were delighted when he did so after three seasons in Japan.

"My message would be it's never too early, it's never too late to finish up," he said.

"Everyone wants to keep playing, everyone loves rugby but it only takes that one head knock to (do damage).

"Especially for younger players, they need to make the hard decision.

"The easy decision is to keep playing, the hard choice is to say I'm going to give this up and go and do something else."

Saia plays for London Irish while another brother Colby is at Connacht.