The former world champion will wear a cast for two weeks, said his Quick Step team, announcing the news on Monday.
Titled in 2005, Boonen was also green jersey of the Tour de France 2007. He also won Paris-Roubaix three times, in 2005, 2008 and 2009.
“I’m really disappointed. The circuit was perfect preparation for me and that I was to follow would have brought championships in great shape,” said the rider.