England and Leicester scrum-half Harry Ellis has spoken of his sadness at having to retire after conceding defeat in his battle with a succession of knee problems.
The 28-year-old required a reconstruction of his left knee in 2007 and sustained a second injury in the same area last season.
After taking advice from a top orthopaedic surgeon, the 27-cap international was left with no option but to hang up his boots.
"The most difficult decision for any player to make is about when they have to stop playing," said Ellis.
"But, after taking medical advice, unfortunately I have to announce my retirement.
"I've loved every minute of my rugby career with Leicester, England and the British & Irish Lions.
"I would like to thank the club and medical staff for their help in my time at Leicester and thank all of my colleagues and the fans who have given me such great support.
"This is not the way I wanted to end my career because I have always taken great enjoyment from the game of rugby and I have some very special memories.
"But now I will have to consider other options for the future and take on a new challenge."
Ellis was sidelined for 10 months after rupturing anterior cruciate ligaments in 2007 and made just 24 of his 173 Leicester appearances in the three years since.
The Tigers academy product, who was capped on last year's Lions tour to South Africa and has played all his club rugby at Welford Road, was then struck down again last season.
He was capped by England at every level from Under-16 to Under-21, and also appeared for the 'A' and sevens teams. He made his Test debut against South Africa in 2004.
Leicester head coach Richard Cockerill said: "Harry is a local lad who made a big impression when he first broke into the Tigers team as a teenager.
"He has always had a great strength of character and was afraid of nothing when he wore a Tigers shirt.
"It's always a sad day when injury ends the career of any player, and Harry has been a valuable and popular member of the squad here for almost 10 years.
"We wish him well in whatever the future may hold for him and thank him for his service to the Club."
England manager Martin Johnson, who played alongside Ellis at Welford Road in the latter stages of his own career, admitted he would me missed by club and country.
"I was sorry to hear the news about Harry having to retire from the game because of injury," said Johnson.
"Harry has been an excellent player who always gave everything for Leicester and England.
"From the first time he was involved it was obvious to everyone in the Tigers squad that he was a special talent and that he'd make a big impact for Leicester and England.
"I'm sure that if he'd been fit Harry would have continued to make a huge contribution to his club and country for many years to come.
"On behalf of the England squad I'd like to wish Harry all the best for the future."
Ellis' last appearance for England was in the 26-12 victory over Scotland at Twickenham in March last year.