Iliac pin and adapter

Apparatus for mounting in a bone of a patient, comprising:

• a rigid elongated member defining a central axis, the rigid elongated member having a distal section, a proximal section, and an intermediate section connecting the distal and proximal sections;
• n helical blades, formed in the distal section, distributed about the central axis, each of the n helical blades having an acute helix angle greater than zero and less than 45°, wherein n is a whole number greater than one, wherein the n helical blades are configured to penetrate into the bone and engage stably therein, and wherein the n helical blades taper by respective tapering planes to a common point at a distal tip of the distal section, so that the distal tip can act as a dilator;
• and a plurality of ribs, formed on an outer surface of the proximal section, each of the plurality of ribs being parallel to the central axis, wherein the proximal section further comprises one or more circular grooves positioned orthogonal to the central axis.