Patent ID: 8075602

Claim:
An implant assembly adapted to be fixed to a bone using at least one bone screw having a thinner region and a thicker region, the implant assembly comprising: an implant member, wherein the implant member has an aperture extending through the implant member, wherein the aperture includes a first region sized to permit the thinner region of the bone screw but not the thicker region of the bone screw to pass through and the aperture includes a second region sized to permit both the thinner region of the bone screw and the thicker region of the bone screw to pass through; a first interior perimeter surface in the implant member defined by the first region of the aperture; a second interior perimeter surface in the implant member defined by the second region of the aperture; and a washer disposed within the aperture in the second region thereof, wherein the washer has a hole, the hole having a longitudinal axis and being large enough to permit both the thinner region of the bone screw and the thicker region of the bone screw to pass through, wherein the washer has at least a first sidewall region with a first wall thickness and a second sidewall region with a second wall thickness, the first and second wall thicknesses being defined in a plane normal to the longitudinal axis of the hole, wherein the first wall thickness is greater than the second wall thickness; wherein, when the bone screw is inserted in the aperture of the implant member and the hole of the washer such that the thicker region of the bone screw is in the second region of the aperture, rotation of the washer causes movement of the first region of the washer relative to the second interior perimeter surface such that the washer applies force to the bone screw to press the bone screw against the implant member and to fix the bone screw in orientation relative to the implant member.