The 29-year-old New Zealand centre-back was signed on an initial 18-month deal in January 2005 after a short trial.
Last season he was badly disrupted by injury with the player undergoing a major hamstring operation last August and only returned to action in January.
"I'm delighted for the club and for Ryan," Mark Hughes told the club's website.
"He's my captain and will be very influential in helping to shape the progress of the club."
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