System and method for stabilizing the human spine with a bone plate

A bone plate system for joining vertebrae comprising:

• a plate having a first opening through the plate and a fastener opening through the plate, wherein a portion of the plate forms a wall of the fastener opening;
• a ring disposed within the fastener opening;
• a bone screw comprising a head and a shank;
• wherein an inner surface of the ring is configured to threadly engage the head such that the ring inhibits backout of the bone screw from the fastener opening;
• wherein the head of the bone screw and the ring are configured to couple together without fixedly engaging the ring to the plate such that an outer surface of the ring is curved to permit the ring to swivel within the fastener opening after the ring is placed in the fastener opening and before the head of the bone screw is screwed into the ring;
• and
• wherein as the head of the bone screw is screwed into the ring, the head applies a radial force to the ring to cause the ring to expand within the fastener opening and create a fixed connection between the bone screw and the plate at a selected angle.

A bone plate system comprising:

• a plate comprising a first opening and a second opening;
• a first ring placed in the first opening, wherein an outer surface of the first ring is curved to permit the first ring to swivel within the first opening;
• a first bone screw configured to be placed into the first opening to couple the plate to a first bone portion, wherein a head of the first bone screw couples to the first ring, wherein the head of the first bone screw is configured to threadly engage and be screwed into the first ring, and wherein before the head of the first bone screw is screwed into the first ring to create a fixed connection between the first bone screw and the plate, the first ring inhibits removal of the first bone screw from the first opening without the first ring becoming fixedly engaged to the plate;
• a second bone screw configured to be placed into the second opening to couple the plate to a second bone portion;
• and
• wherein swiveling of the first ring within the first opening allows the first ring to be positionable within the first opening so that the first bone screw is at an angle less than about 40° relative to a longitudinal axis of the first opening when the bone screw is placed in the first bone portion.

A spinal fixation kit comprising:

• a plate comprising openings for fasteners that fasten the plate to bone;
• a plurality of fasteners configured to affix the plate to bone portions;
• and
• a plurality of rings, wherein a ring of the plurality of rings is configured to threadly engage a head of a fastener of the plurality of fasteners through an opening of the openings and an outer surface of the ring is curved to permit the ring to swivel within the opening so that the ring and fastener combination couples the plate to a bone portion and so that the ring and fastener combination inhibits removal of the fastener from the plate without the ring fixedly engaging the plate before the head of the fastener is screwed into the ring, wherein as the head of the fastener is screwed into the ring, the head applies a radial force to the ring to cause the ring to expand within the opening and create a fixed connection between the fastener and the plate at a selected angle.