Lusk’s design has the general form of an obstetrical forceps, but is constructed with handles, shanks and blades of such strength that a fetal skull may be crushed without regard to the direction or the aspect of the parts engaged.  Likewise, it has both cephalic and pelvic curves.  However, unlike a forceps, the tips of the blades are in contact when the instrument is closed.  Its branches are joined with a pin and button lock.  The crushing force is provided by a hinged cross-bar attached to the lower blade, contact by the upper being secured by a winged nut of large dimension and capable of generating a great deal of force.  The surgeon may seize the head at levels above the pelvic brim, thus employing the instrument as a tractor.