Patent ID: 8152838
Filing Date: 2012-04-10
Classification: A61B

Abstract:
1. A Bone fixation system comprising: a bone screw including a head portion with an annular groove and a concentric pin bore extending into a threaded portion; an expandable ring including a substantially circular outer rib with an expansion gap retained within the annular groove and expansion ribs protruding from the outer rib toward the pin bore to form a pin orifice, wherein a diameter of the pin bore is greater than a diameter of the pin orifice; a pin slidably received in the pin bore with a varying outer profile that engages the expandable ring to selectively expand the expandable ring from an un-expanded state to an expanded state, wherein the pin includes a conical entry taper, the conical shape stopping at an entry body forming a cylindrical shape, the cylindrical shape becoming frusto-conical in a retention cut-out portion, and returning to the cylindrical shape in a gradual expansion portion; and a bone plate including a thru-bore with an entry diameter that receives the bone screw, wherein an outer diameter of the expandable ring is less than or equal to the entry diameter in the un-expanded state and greater than the entry diameter in the expanded state.