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 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."
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.— Chelsea FC (@ChelseaFC) February 13, 2018
Mason joined Hull in August 2016 having made 70 appearances for Tottenham, where he had come through the youth system.
19. September 2018
|BREAKING NEWS: Ronaldo sent off on Champions League debut for Juve|
|Shakhtar Donetsk 2 Hoffenheim 2: Maycon denies Nagelsmann´s side|
|Ajax 3 AEK Athens 0: Tagliafico at the double in opening win|
|Dalot makes debut, Martial starts for Manchester United|
|India avenge ICC Champions Trophy loss with big win over Pakistan|
|Ronaldo makes Champions League debut for Juve|
|Lopetegui picks Navas over Courtois for Champions League clash with Roma|
|Willian very happy under Sarri after Conte row|
|Sarri deals blow to Chelsea kids´ Europa League hopes|
|Mendy out for Manchester City as Aguero makes bench|
|Cech accepts performances key to securing Arsenal stay|
|Monchi rules out Spain return amid Barcelona rumours|
|Durham skittled for 61 and 66 on the same day|
|Kane isn´t a machine – Lamela defends misfiring Spurs star|
|Hazard left out of Chelsea squad for PAOK trip|
|Tiger feels close to ending drought after achieving Tour Championship goal|
|Leno in line for Arsenal chance in Europa League|
|Gazidis leaves Arsenal in good shape, insists Emery|
|Eagles bring back WR Matthews, place Wallace on IR|
|England include Stokes, Hales and uncapped seamer Stone in ODI squad|
|Suwon Bluewings 0 Jeonbuk Motors 3 (aet, 4-2 on penalties): Quarter-final comeback ends in spot-kick|
|Australia captain Paine ready to slog it out with Pakistan|
|Nadal pulls out of China Open & Shanghai Masters with knee injury|
|Ostapenko begins Korea Open defence with victory|
|Joshua v Povetkin: How Olympic super heavyweight champions have fared|
|Liverpool ´made a point´ with PSG victory - Gomez|
|Osaka wows Tokyo crowd on WTA return|
|Excited Povetkin arrives in England for Joshua showdown|
|Kovac patience with Sanches set to reap rewards|
|Kovac: Madrid strong without Ronaldo, Messi is the best|
|ATP suspends umpire Lahyani over Kyrgios ´pep talk´ at US Open|
|North and South Korea seek to co-host 2032 Olympics|
|Ampadu signs long-term Chelsea contract|
|Don´t blame Neymar, PSG players all guilty - Thiago Silva|
|Real Madrid seek to plug Ronaldo scoring gap – Champions League in Opta numbers|
|Brewers allow Cardinals to inch closer with loss to Reds|
|Manchester is still red – Depay ahead of Lyon´s clash with City|
|Orioles become first pro team to wear braille jerseys|
|Klopp hails ´brilliant´ Henderson|
|PSG attack lacked aggression, says Tuchel|
|Atletico Tucuman 0 Gremio 2: Libertadores holders draw first blood in QFs|
|Thomas plays down wrist worry|
|Rakitic wants more from Barcelona hat-trick hero Messi|
|My players aren´t s*** – Pochettino defends Spurs squad|
|Cubs reliever Morrow won´t return this season|
|Tebow expected to be back in Mets organisation next season|
|Inter can compete against anyone – Icardi revels in Champions League victory|
|Tuchel: PSG loss to Liverpool not logical or correct|
|Sturridge in best shape I´ve seen – Klopp|
|Milojevic celebrates ´fantastic´ occasion after Red Star´s 26-year wait|
|Rodrigo and Simeone salute Griezmann display|
|Seahawks DE Clark on Bears QB Trubisky: He´s nothing special|
|Carroll says Wilson has been ´over-trying a little bit´|
|Judge returns to Yankees´ starting lineup|
|Napoli boss Ancelotti takes aim at Red Star time wasting|
|Favre admits young Dortmund stars struggled in Bruges|
|Otavio would trade goal for Porto victory as he bemoans Schalke draw|
|Championship Review: Pacesetters Leeds crush Preston, Villa end five-game winless run|
|Neymar world-class but not a defender - Klopp says Liverpool targeted PSG star|
|Waiters injury update: Heat guard unlikely to be ready for start of season|
18. September 2018
|Gojowczyk eliminates returning Tsonga in Metz|
|Liverpool enjoying best start in 57 years after PSG win|
|Galatasaray 3 Lokomotiv Moscow 0: Terim´s side make light work of Russians|
|Club Brugge 0 Borussia Dortmund 1: Super sub Pulisic scores late winner|
|Schalke 1 Porto 1: Fahrmann saves one penalty, but Otavio scores another|
|Red Star Belgrade 0 Napoli 0: Points shared as Italians fail to make possession pay|
|Liverpool 3 Paris Saint-Germain 2: Firmino strikes late as Reds edge five-goal thriller|
|Monaco 1 Atletico Madrid 2: Costa and Gimenez seal comfortable win|
|Chaos reigns in Serie B as league denies suspension claim|
|India secure Asia Cup victory despite valiant Hong Kong effort|