Bayern Munich defender Breno underwent surgery yesterday at a clinic in Augsburg after he suffered a recurrence of inflammation in his right knee, the Bundesliga outfit have announced. \"We can\'t say for some time how long Breno will be unavailable,\" club doctor Hans-Wilhelm Mueller-Wohlfahrt said on the club\'s website. The 22-year-old Brazilian has only played for Bayern 13 times since his arrival from Sao Paulo in the summer of 2010.