Rodwell facing three months out
The 19-year-old suffered the injury during Everton’s 1-0 defeat at Aston Villa in August following a challenge with Stephen Warnock, which forced him off before full-time.
As a result, Rodwell was forced to withdraw from England's under-21 squad, with Everton’s medical team unable make a full diagnosis immediately due to swelling around the ankle.
The full extent of the damage has now been confirmed and manager David Moyes must cope without the talented teenager until December, although he had hinted that he would use him sparingly until the second half of the season.
Rodwell, who signed a new five-year deal in the summer amid reported interest from Manchester United and Chelsea, is regarded as one of the brightest talents at Goodison Park.
"Jack is a really good player, he is going to be an excellent player,” Moyes said of the youngster in August.
"We have done well with young players over the years and we will bring them through at the right time and in the right way.
"Jack will play lots of games for Everton and go on to become a good player, but it will be in our time."
Rodwell impressed during the Toffees' 5-1 Carling Cup win against Huddersfield Town and was subsequently handed his first Premier League start of the season against Villa, only to suffer the untimely blow.
By Vaishali Bhardwaj