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 have 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 (AEDT) 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."
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."
Mason joined Hull in August 2016 having made 70 appearances for Tottenham, where he had come through the youth system.