The 25-year-old picked up the injury during the Highlanders 40-20 loss to the Crusaders in Dunedin on Saturday.
A stray boot collected his leg early during the opening half.
Dickson will be sidelined for up to four months. There is a slim chance he could be available for the back end of Otago’s season.
Dickson will be a big loss. He had established himself in the Highlanders' tight-five and was arguably in career-best form. He has been replaced in the side by Geoff Cridge.