The former Kenyan captain suffered the injury during the Commonwealth Games in Glasgow last month against New Zealand and will not be available for selection until February next year.
His absence will be a major blow for Kenya, who are bidding to finish among the the top four nations in the new season which gets underway at Gold Coast in Australia in October.
The competition will act as an Olympic qualifier with the top four teams earning automatic qualification to the 2016 Games in Rio de Janeiro, where rugby sevens makes its debut.
Kenya finished seventh in the rankings last season under their new coach Paul Treu from South Africa and lost to Wales in the Commonwealth Games plate semi-final in Glasgow.
The team has already started training for the new season and will test several newly-capped players in this month’s national Safaricom sevens tournament in Nairobi.