Hibbard will definitely miss league games with Leinster and Ulster, plus the EDF Cup semi-final with Gloucester.
And he is a doubt for the Ospreys’ Heineken Cup quarter-final on 12 April against Munster at Thomond Park.
However, the Ospreys can call on another Wales hooker in Huw Bennett, who has recovered from his injury problems earlier in the season.
Hibbard will face a two-week period before he can bear weight on his injured right ankle and will then commence an intensive rehabilitation programme.
At this stage the Ospreys are optimistic that he will be back in action within the predicted six-week window.
Hibbard was capped by Wales during their summer tour to South Africa in 2008 and has enjoyed an impressive season at the Liberty Stadium.
