Patent ID: 8048131
Filing Date: 2011-11-01
Classification: A61B

Abstract:
1. A bone fixation screw comprising: a threaded screw shank and a screw head having upper and lower ends with said screw head lower end secured to a proximal end of said screw shank, said screw head having substantially frustospherical shaped side surfaces and split into segments at the upper end, each segment having an end, the screw head having an axial bore extending therethrough, whereby said head is radially expandable at said upper end; and an expansion pawl centrally received in said screw head, the screw head comprising a plurality of teeth positioned along the ends of the segments of the screw head, the ends of the segments facing the axial bore, the teeth extending into the axial bore radially inwardly with respect to a circle defined by the ends of the segments, each of the teeth extending in a direction toward the expansion pawl, each of the teeth forming a cam mechanism for expanding said screw head upon axial rotation of said expansion pawl.