Burger lasted just ten minutes of Namibia's crunch match with Georgia before he was led off the pitch after a blow to the head.
“It was a huge disappointment that I could not complete last night’s match and an even bigger disappointment that I will not be able to play on Sunday," Burger said.
"I am very proud of my team and it is not the way that you would want to end an international career. But that’s the game of rugby for you.”
"I was really hoping to finish my international career in style, the emotions were building up to the match on Sunday and to have it ended abruptly like this after just 10 minutes is a bit of a setback.
But I have no regrets, I have had a wonderful time playing for Namibia with my friends.”