US Patent 8992581 Bone plate and bone plate assemblies including polyaxial fasteners

A bone plate system for fixation of bone includes a bone plate and a first fastener. The bone plate includes a bone contacting surface, an upper surface, and a first opening extending between the bone contacting surface and the upper surface. The first opening includes a lower portion, a non-threaded upper portion, and a threaded portion. The threaded portion includes threads and converges towards the lower portion. The lower portion includes a smallest diameter of the first opening. The first fastener includes a head at least partially comprising a spherical portion and a first material. When the first fastener is inserted into the first opening, the threads of the first opening form threads in the first material on the head of the first fastener to secure the first fastener in place at one of a plurality of possible angles within the first opening.