Osteoporatic screw and expansion sleeve

Abstract

The invention is a bone screw apparatus. The bone screw apparatus has two specialized functions for stabilizing the screw within a bone. The first is a mechanical structure that anchors the screw within a bone and the second is a structure that allows injection of bone cement through the screw assembly and into the interior structure of the bone. The anchoring mechanism functions by an expandable member that slides concentrically over the shaft of the screw. When the expandable member is forced over a portion of the screw shaft with an enlarged diameter, the expandable member extends radially from the screw shaft, and the bone screw is anchored to the interior structure of the bone. The injecting function of the bone screw apparatus functions through the use of a hollow core within the screw shaft. The hollow core of the screw shaft has an inlet at the top of the shaft and at least one outlet near the tip of the screw shaft. Once the screw shaft is inserted into the interior structure of a bone, bone cement may be injected into the inlet at the top of the screw shaft. The bone cement travels through the hollow core of the screw shaft and is extruded out the holes near the tip of the screw shaft. The bone cement fills the void spaces within the bone structure and strengthens the bone.