Hull City midfielder Ryan Mason has been forced to retire from football following the head injury he sustained at Chelsea in January 2017, the Championship club has confirmed.
Mason, 26, has not played since a clash of heads with Gary Cahill at Stamford Bridge left him with a fractured skull and requiring surgery.
The former Tottenham man, who spent a week in hospital following his operation, said he felt "lucky to be alive" after the incident.
Mason won a single cap for England - against Italy in 2015 - and had been hopeful of a return to action, saying in May that he was looking forward to "returning a better player".
However, Hull released a statement on Tuesday to announce that Mason had retired from the sport with immediate effect.
"Ryan has sought the guidance of numerous world-renowned neurologists and neuro surgeons who have all advised that a return to competitive football is not advised," read the release.
"Ryan would like to put on record his thanks to all at the club who have aided his recovery to this point and he his is indebted to them for their support and compassion over the past 12 months."
Mason joined Hull in August 2016 having made 70 appearances for Tottenham, where he had come through the youth system.
Chelsea later tweeted: "Everybody at Chelsea Football Club sends our best wishes to Ryan Mason following his retirement.
"Good luck in whatever you choose to do next, Ryan."
And Mason has revealed he had "no option" but to retire after working hard on his return to action.
"I can confirm that following specialist medical advice I am having to retire from playing professional football," Mason said in a statement.
"I have worked tirelessly in order to be able to return to the pitch. Unfortunately, having taken expert medical advice I now have no option but to retire due to the risks involved given the nature of my injury.
"I am and always will be eternally grateful for the incredible network of people around me who have helped me to recover from what was a life-threatening injury in January 2017.
"Thank you to my amazing fiance, Rachel, who has been by my side and lived every single day with me since the injury, helping to give me the strength I've needed no matter how tough things got.
— Tottenham Hotspur (@SpursOfficial) February 13, 2018
"We are so lucky to have now become the proud parents of our perfect baby boy George."
Mason is a product of the Tottenham youth system and won his only England cap against Italy in March 2015 before departing for Hull in the August of the following year.
"I am so proud to have come through the ranks to play for my club, the club I love," he added. "To have had the honour of captaining the team fills me with immense pride.
"Representing my country is an honour that nobody can ever take away from me and something that I am so proud to have achieved.
"I'm retiring from the game with my head held high having done everything in my power over these past 13 months to have given myself every opportunity to return to the pitch.
"I love the game, I always will and I am excited to see where football will take me next."