The 27-year-old has not played since Boxing Day 2017 when he was injured in an aerial collision with Scarlets' Steffan Evans.

That was the third incident in 2017 to have affected John, who made his Ospreys debut seven years earlier.

"It hasn't been easy for me over the last couple of years," John said.

"It's taken so long for me to recover, after thinking about it long and hard, the best decision for me, the only one really, was to retire.

"Rugby has been my life, but I realise that my long-term health is more important.

"In the end, my decision was an easy one, particularly having spent time outside of the game and recognising there is life away from the rugby pitch."

The Morriston-born player was recognised for his service to the region when he was presented with his shirt at their end-of-season dinner in April 2018 as one of the players leaving at the end of the campaign.

John, capped at all age-grade levels by Wales, will now concentrate on his work as a personal trainer in London.