Patent ID: 8172885

Claim:
A device for stabilization of adjacent vertebrae of a spine, the device comprising: a bone plate; a plurality of bores in the bone plate; a bone anchor configured for extending through one of the bores; a head of the bone anchor having a spherical outer surface and a shank depending from the head; a pair of spaced, flat portions of the one bore that extend substantially parallel to one another and which are spaced by a predetermined fixed distance; a rotary anchor lock collar member extending about a central axis for being rotatably received in the one bore; a curved inner surface of the rotary anchor lock collar member adapted to engage the spherical outer surface of the head of the bone anchor to permit the bone anchor to be rotationally driven through the one bore along one of a plurality of different driving axes that are transverse to the central axis and into a vertebral bone; an upper portion of the rotary anchor lock collar member having notches spaced circumferentially thereabout for receiving a driving tool therein to rotate the rotary anchor lock collar member in the one bore; a lower portion of the rotary anchor lock collar member having a split-ring construction so that the anchor lock lower portion has facing circumferential ends that are spaced apart from one another by a gap therebetween; a larger dimension and a smaller dimension of the rotary anchor lock lower portion having respective axes that extend through the center of the split ring rotary anchor lock collar member substantially orthogonal to each other with the larger dimension being greater than the predetermined fixed distance and the smaller dimension being less than the predetermined fixed distance; and cooperating inner and outer surfaces of the one bore flat portions and the anchor lock lower portion respectively, which cause the facing ends to shift toward each other with approximately ninety degrees of rotation of the anchor lock collar member, after the bone anchor has been driven through the one bore and into the vertebral bone, so that rotation of the rotary anchor lock collar member is independent from the rotational driving of the bone anchor with the rotating anchor lock collar member being rotated from an open, bone anchor receiving configuration with the larger dimension axis oriented to be substantially parallel to the bore flat portions to a clamped, bone anchor locking configuration with the larger dimension axis oriented to be substantially perpendicular to the bore flat portions to cause the facing ends to shift toward each other to reduce the size of the gap therebetween so that the bone anchor extending through the one bore and the rotary anchor lock collar member therein is locked in the one bore against back out therefrom and against polyaxial movement relative to the bone plate and the rotary anchor lock collar member.