Dons manager Mark McGhee explained: "Fraser has had his X-ray and it would appear there is no breakage.
"There is certainly ligament damage, which can be a lengthy process. The prognosis is for about four to six weeks."
Fyvie was injured shortly before Hibs netted two late goals to deny nine-man Aberdeen a SPL point following red cards for Maurice Ross and Chris Maguire.
"Fraser has been important in the way we have played, in the last three games in particular," McGhee told RedTV.
"We are all disappointed for him, at this early stage in his career, he is just getting started.
"But it's an injury that will fix itself and he'll be back."
Source: Team_Talk
