An expandable bone fixation screw with removable core pin

A bone screw (100, Fig.1) and method of using the same, are described. The bone screw includes a head 110 including an end surface 112 with an opening; a distal portion 130; and an intermediate portion 150 extending between the head and distal portions; the intermediate portion including a tubular body which includes an expandable portion 152, and an inner bore 156 in communication with the opening of the head portion. A core pin (190, Fig.9) is removably coupled within the inner bore of the intermediate portion. The core pin may include a first set of threads (180, Fig.9) at a first end for mating with a set of threads 122 on the inner bore proximate the head portion, and a second set of threads (182, Fig.9) at a second end for mating with a set of threads 124 on the inner bore proximate the distal end. The inner bore may terminate at an end beyond the expandable portion. The core pin may stretch and/or stabilize the expandable intermediate portion. The bone fixation screw provides a quantifying and known amount of compression force across a fracture at predetermined and predictable levels.