You didn't mentioned the name of the examination, for which you are asking the eligibility criterion. Now as you hand is properly functioning despite of having some problems, I don't think it will create much problem. But you must know that for every course there are some maximum criteria of disability to be allowed. So you have to check what the conditions and accordingly you have to visit a medical practitioner for the health certificate.

To get a more specifics answer, repost the question with proper question specifics (provide the name of the course/the examination you want to appear in) so that we can provide you all the information required.

Goodnight :-)