Huget out of World Cup
A tearful Huget was forced off during France's 32-10 victory over Italy in their opening World Cup match on Saturday.
His place was taken by Castres wing Remy Grosso.
He has injured the ligaments in his right knee, Saint-Andre said in an interview.
"A big thought for Yoann Huget, a model player in terms of his commitment – great guy. We're all with you, [have a] good recovery," Saint-Andre wrote on social media.
The 28-year-old Toulouse star Huget was pulled out of the France squad before the last World Cup in New Zealand in 2011, after missing three doping tests, for which he was handed a three-month suspension.
His Toulouse teammate Maxime Medard, who can play at wing or fullback, and Castres centre Remi Lamerat, who began his career at Toulouse, are the favourites to replace Huget for the rest of the tournament.
Huget was forced off after 56 minutes of Saturday's match at Twickenham against Six Nations rivals Italy, who are in Pool D alongside Ireland, Canada and Romania.
Huget was running down the wing with ball in hand when he pushed off his right leg to cut inside a defender, only to collapse to the ground, wincing in pain.
He was seen holding his face in his hands before being helped from the field by two members of the French medical staff.
He could then be seen crying as he sat on the bench beside the pitch, while being consoled by various people, including French federation official, and legend Serge Blanco.
Huget made his debut for France in 2010 and has scored seven tries for his country.
Source: Agence France-Presse
