Cressy saw a specialist on Monday and the good news is that he will only be sidelined for a further month after it was found some fibre tissue has detached from the bone.
It was feared an absence of upto four months could be expected if he went under the knife, but this isn't required.
Meanwhile boss Andy Scott has blasted the agent of trialist Alassane N'Diaye, who lasted just 45 minutes of the reserves game with Hartlepool on Monday.
"I'd spoken to the agent who said he was match fit and ready to play which wasn't an honest assessment," said Scott.
"I know what he can do from his time with Crystal Palace but clearly N'Diaye wasn't fit enough to play for us."
The 29 year-old won't be considered again until he can prove his fitness.