The 23-year-old is expected to be on the sidelines for three months after suffering a double leg break at the weekend.
The former England Under-19 picked up the injury during Derby’s 1-0 defeat to Ipswich Town at the iPro Stadium on Saturday afternoon.
Gutted is an understatement but just have to get on with it.. 3 month lay off, so will be working very hard to make the start of next season— George Thorne (@GeorgeThorne15) May 8, 2016
Would love to be involved in the playoffs but not to be.. Wishing my team mates all the best!!— George Thorne (@GeorgeThorne15) May 8, 2016
Thorne scored two goals and created 29 chances in 34 Championship appearances for Derby this season.
The former West Bromwich Albion midfielder had a pass accuracy of 86% and a shot accuracy of 37%, and has won 37 headers, 30 dribbles and 80 tackles.
Derby will take on Hull City at the iPro Stadium in the first leg of the playoffs this coming weekend. The second leg of the tie will be held at the KC Stadium next week.