Polyaxial locking mechanism

A bone plate system, comprising:

• a bone plate including a bone facing surface, an opposing outer surface, and at least one linearly tapered aperture extending through the bone plate and having a longitudinal axis and a threaded internal surface, the linearly tapered aperture defining a first taper angle between the longitudinal axis of the linearly tapered aperture and the threaded internal surface, the outer surface further including a first counterbore centered about the longitudinal axis of the linearly tapered aperture, and the bone facing surface further including a second counterbore centered about the longitudinal axis of the linearly tapered aperture, the threaded internal surface being continuously linearly tapered from the first counterbore to the second counterbore;
• and
• at least one fastener including an elongate shaft and a linearly tapered head having a threaded external surface and a longitudinal axis, the linearly tapered head defining a second taper angle between the longitudinal axis of the linearly tapered head and the threaded external surface, wherein a plurality of circumferentially spaced recesses are formed in the linearly tapered head and define interruptions in the threaded external surface of the linearly tapered head;
• wherein the first taper angle of the linearly tapered aperture is greater than the second taper angle of the linearly tapered head such that the at least one fastener can be inserted within the at least one linearly tapered aperture at a plurality of different insertion angles.

A bone plate system, comprising:

• a bone plate including a first surface and a second surface, the bone plate including at least one threaded aperture, the threaded aperture being conically tapered between the first surface and the second surface at a first taper angle;
• and
• at least one fastener including an elongate shaft and a threaded head, the threaded head being conically tapered between a proximal end of the threaded head and a distal end of the threaded head at a second taper angle different from the first taper angle, wherein a plurality of circumferentially spaced recesses are formed in the threaded head and define a plurality of threaded tabs;
• wherein the first taper angle is between 10 degrees and 20 degrees, and wherein the second taper angle is between 5 degrees and 15 degrees;
• and
• wherein the at least one fastener is configured for insertion within the at least one threaded aperture at a plurality of different insertion angles while achieving a locking engagement between the threaded head and the threaded aperture.