The 23-year-old has been plagued by injuries since he joined from Derby in 2008 and suffered his latest setback when he landed awkwardly during the FA Cup win over Cheltenham a fortnight ago.
"He is going to be out for the foreseeable future," said boss Nigel Adkins.
"It is a totally different injury to anything he would have had previously and you just feel it is very unfortunate for him."
Source: PA
Source: PA