Methods and devices for retaining bone plate anchors

A bone plating system, comprising:

• a bone plate including at least two holes therethrough between an upper surface and a lower surface of said bone plate, each of said holes to receive an anchor for engaging said bone plate to a bony segment, said bone plate including at least one receptacle between said pair of holes;
• a retaining element including a distal shank portion engaging said plate in said receptacle when rotated in a first direction about a rotational center of said retaining element and a proximal head portion extending about said shank portion, said proximal head portion including a top surface opposite said distal shank portion, said top surface positioned adjacent said upper surface of said bone plate, wherein when viewed in a direction looking along said rotational center toward said top surface said head portion includes an outer perimeter that is visible from said direction, said outer perimeter extending about said rotational center of said retaining element, said outer perimeter being interrupted by a first relief extending inwardly toward said rotational center and a second relief opposite said first relief extending inwardly toward said rotational center, said outer perimeter further including:
• a first perimeter portion visible from said direction that extends partially about said rotational center along a first arc defined by a first radius extending from said rotational center, said first perimeter portion extending from said first relief in said first direction;
• a second perimeter portion visible from said direction that extends partially about said rotational center along a second arc defined by said first radius, said second perimeter portion extending from said second relief in said first direction;
• a first camming portion that is visible from said direction that extends along a first arcuate surface between said first perimeter portion and said second relief, said first arcuate surface including a circumferential taper that is visible from said direction that tapers toward said rotational center in said first direction;
• and
• a second camming portion visible from said direction that extends along a second arcuate surface between said second perimeter portion and said first relief, said second arcuate surface including a circumferential taper that is visible from said direction that tapers toward said rotational center in said first direction, wherein at least one of said first perimeter portion and said first camming portion is positionable in contact with the anchor in one of said at least two holes while at least one of said second perimeter portion and said second camming portion is positionable in contact with the anchor in the other of said at least two holes;
• wherein said retaining element includes a first axis extending through said rotational center and bisecting first and second reliefs and a second axis orthogonal to said first axis and orthogonal to said rotational center, wherein said first arcuate surface of said first camming portion circumferentially tapers on said outer perimeter at least from said second axis to said second relief in said first direction and said second arcuate surface of said second camming portion circumferentially tapers at least from said first axis to said first relief in said first direction so that a radius of said outer perimeter where said first and second camming portions join respective ones of said second and first reliefs is less than said first radius of said outer perimeter where said first and second perimeter portions join respective ones of said first and second reliefs.