The 26-year-old took the decision reluctantly following extensive examinations and on the best medical advice available, the Scottish Rugby Union has announced.

The risk of serious injury was too great to consider continuing in the game.

Stewart said, "I would like to say how much I have enjoyed my rugby career.

"I have seen a great deal of the world and met a great number of people.

Greatly appreciate

"I have achieved more than most in rugby.

"Also, a simple thank you to David Leslie, Graham Hogg and Jeremy Richardson for making me realise the facets of the game that I have appreciated the most.

"To finish I would like to give my best wishes to my team-mates at Edinburgh Reivers and good luck for the coming season, especially to our new recruits."

Reivers chief executive Nick Oswald said: "Barry's enforced retirement from rugby is extremely sad news.

Enormous contribution

"Although it must be a devastating blow for him, he has faced up to the stark facts in a very philosophical and mature way.

"Over the past three seasons with the Reivers, Barry has been the model of consistency, barely missing a game.

"And it was this consistency and determination which earned him a recall to the international arena in New Zealand last summer four years after winning his first cap.

"I am sure that he would have gone on to win many more caps if it had not been for this untimely injury.

"On behalf of everybody involved with the Reivers, may I take this opportunity to thank Barry for his enormous contribution to Scottish rugby and to wish him the very best of luck in the future."