Anterior spinal polyaxial locking screw plate assembly having recessed retaining rings

A polyaxial locking screw plate assembly the for immobilization of vertebral bones, via fixation to surfaces thereof, comprising:

• a plate having a plurality of through holes;
• wherein at least one of said plurality of through holes includes an annular recess formed in an upper sidewall portion of said hole;
• a snap-ring being disposed in said annular recess;
• a corresponding plurality of coupling elements, each of said coupling elements being insertable into a corresponding one of said through holes;
• and
• a plurality of bone screws, each of said bone screws having a semi-spherical head portion and a shaft, said shaft portion being insertable through the corresponding through hole and into the bone, and said semi-spherical head portion being rotationally freely mounted in the coupling element prior to insertion and such that the shaft of the bone screw and the coupling element may be inserted into a corresponding through hole, said snap ring deflecting outward during the insertion of the coupling element to permit the coupling element into the through hole, and said snap ring snapping back to an undeflected condition once the coupling element has fully seated in the through hole, thereby preventing the coupling element from backing out of the through hole, and said shaft of the bone screw may be inserted into the bone at a selected angle within a predetermined range of angles including non-perpendicular angles relative to the plate and thereby locking said coupling element and said semi-spherical head to said plate at said selected angle.