DeMerit has struggled with injuries throughout his Major League Soccer career.
Most recently, the centre back tore a tendon in his left ankle in a 3-3 draw with the Philadelphia Union on June 12. He was expected to miss six-to-eight weeks.
DeMerit was the first player the Whitecaps signed in 2010 when Vancouver was preparing to enter Major League Soccer.
He had played for Watford of the English Premier League for six seasons before joining the Whitecaps.
The 34-year-old from Green Bay, Wisc., played 25 games with the United States, including starting four games for the Americans in the 2010 World Cup.