Former West Ham and Wales midfielder Jack Collison has announced his retirement from football, aged 27.
Collison made his West Ham debut on New Years' Day 2008 and progressed to full international honours later that year.
In March 2009, he suffered a dislocated kneecap during West Ham's 1-0 win over Wigan Athletic and, although he was only sidelined for an initial two months, knee problems continued to plague the rest of his career.
Collison played 121 times for West Ham, and won the last of 17 Wales caps in March 2014.
That season included loan spells with AFC Bournemouth and Wigan before West Ham released Collison, and a trial period at QPR and short-term contract with Ipswich Town in 2014 did not yield a single competitive appearance.
He played 12 times in all competitions for League One Peterborough United this season, where he is now the coach of the Under-18 side.
"The nights I wake up in pain, or the mornings where I struggle to walk, will be a constant reminder I was lucky enough to play the game I love," said Collison in a statement on his official website.
"I would be lying if I said I didn't still wake up some mornings feeling good and think 'one more try'. But that would be unfair. On myself, my fellow professionals and even more so my family. I have put them through hell fighting this battle, over the past couple of seasons especially.
"I don't want to be remembered for being useless and just picking up my money, I want to bow out with some of my pride intact."