iščašiti

1. (of a joint) to dislocate
   Pao je na treningu i iščašio rame. — He fell during training and dislocated his shoulder.
   Iščašila sam zglob dok sam silazila niz stepenice. — I dislocated a joint going down the stairs.

In everyday speech it is often used loosely for a sprain as well, instead of uganuti.