Hull City have announced that midfielder Ryan Mason is to retire from professional football with immediate effect, following a head injury sustained last year.
The 26-year-old suffered a fractured skull almost 13 months ago and has been advised not to return to action.
Mason was involved in a collision with Chelsea defender Gary Cahill in January 2017 which has kept him out of action ever since.
Mason, who has one England cap, said in a statement: "I can confirm that following specialist medical advice I am having to retire from playing professional football.
"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."
Mason, who started his career with Tottenham, had several loan spells before joining Hull in 2016.
He won his sole England cap against Italy in March 2015.
A statement on the Hull website said:
"It is with deep regret that the Club has to announce that, following the head injury suffered on 22nd January 2017, Ryan Mason is to retire from football 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.
"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."
Enfield-born Mason joined Tottenham as a trainee and made his Spurs debut against Dutch club NEC Nijmegen in a UEFA Cup tie in November 2008.
Mason had loan spells at Yeovil, Doncaster, Millwall, Leyton Orient and Swindon before returning to Spurs, where he made 70 appearances and scored four goals.
He was called into the England squad and capped in a 1-1 draw with Italy in Turin in March 2015, when he set up Andros Townsend's late equaliser.
Mason joined Hull in August 2016, for a fee believed to be around £13million, and made 20 appearances and scored twice for the Tigers.