An instrument for locating a femoral mechanical axis and identifying the locations of at least three points in space in relation to the center of a femoral head, the instrument including a base member, an extension arm clamp translationally and pivotally attached to the base member, an extension arm translationally and pivotally attached to the extension arm clamp, a swiveling arm pivotally attached to a distal end of the extension arm, the swiveling arm including a lateral locator member at a proximal end and a medial locator member at a distal end, a bracket pivotally attached to the swiveling arm, and a locating arm removably attached to the bracket, the locating arm including a middle locator member.