Most  common position of hymen rupture in a virgin is
Hymen tears

Congenital - Anterion
Intercourse / foreign body - posterolateral
In a virgin, laceration of hymen occurs with the first intercourse
This is the principal evidence of intercourse in a virgin
Tearing of hymen usually occurs postero - laterally or in the middle.

Other conditions causing ruptured hymen before coitus

Accidents
Mastrubation
Instrumentation by doctors
Artifical dilatiation of vagina by foreign bodies for prostitution
Passage of large blood clots.
Anterior
Anterio - lateral
Posterio - lateral
Posterior