Variable angle locking construct for orthopedic applications

A bone fixation kit comprising:

• a plate that includes a void and opposing outer surfaces, the void including one of a counterbore or a countersink and the outer surfaces including first and second openings into the void;
• wherein:
• the plate includes no resilient members;
• no portion of the void is threaded;
• the void includes an inner wall;
• the inner wall includes reliefs along its perimeter;
• the reliefs are configured such that threads of a bone anchor head will deform the inner wall adjacent at least one of the reliefs when the bone anchor mates with the plate;
• measured orthogonal to a long axis of the void, the second opening is wider than the first opening, and
• measured parallel to the long axis, the reliefs are further from the first opening than the second opening.

A bone fixation system comprising:

• a bone anchor;
• and
• a plate;
• wherein:
• (a)(i) the bone anchor includes a head and a body, the head being coupled to the body, (a)(ii) the bone anchor has a long axis, (a)(iii) the body has an outer diameter that is orthogonal to the long axis and the head has an outer diameter that is orthogonal to the long axis, and (a)(iv) the outer diameter of the head is greater than the outer diameter of the body;
• wherein:
• (b)(i) the plate includes an aperture, (b)(ii) the aperture includes a long axis that traverses the aperture but does not intersect the plate, (b)(iii) the aperture includes a first opening and a second opening, (b)(iv) the aperture includes a projection and the projection projects inwardly from a wall of the aperture and towards the long axis, (b)(v) the projection has a first surface and a second surface, and (b)(vi) at least a portion of the first surface is coplanar with a first plane, and (b)(vii) the first plane intersects the long axis at a first angle and the first angle is between 85 degrees and 95 degrees;
• wherein:
• (c)(i) the plate includes no threads between the first and second openings;
• (c)(ii) the first opening directly interfaces a first outer surface of the plate;
• (c)(iii) the second opening directly interfaces a second outer surface of the plate;
• and (c)(iv) the first outer surface of the plate opposes the second outer surface of the plate;
• wherein:
• (d)(i) the first opening has a first maximum diameter that is orthogonal to the long axis;
• (d)(ii) the second opening has a second maximum diameter that is orthogonal to the long axis;
• (d)(iii) the second maximum diameter is greater than the first maximum diameter;
• and (d)(iv) the first opening is configured to receive the head of the bone anchor;
• wherein the head of the bone anchor has a circular cross-section, the cross-section being orthogonal to the long axis of the bone anchor;
• wherein the outer diameter of the head is greater than the outer diameter of the body based on the bone anchor including a tapered portion;
• wherein the tapered portion includes a thread root that tapers outwardly at an angle between 10 degrees and 25 degrees;
• wherein the head of the bone anchor includes a maximum diameter taken orthogonal to the long axis of the bone screw;
• wherein the projection forms a ring that circumnavigates an inner portion of the aperture, the ring including a minimum diameter;
• wherein the maximum diameter of the head of the bone anchor is between 5 percent and 10 percent larger than the minimum diameter of the ring;
• wherein at least a portion of the head of the bone anchor is included in a proximal-most fifth of the bone anchor, the portion of the head of the bone anchor including threads;
• wherein the threads of the portion of the head of the bone anchor have a thread height, the thread height being between 0.0254 mm and 0.3048 mm;
• wherein the threads of the portion of the head of the bone anchor have a crest width, the crest width being between 0.0508 mm and 0.3048 mm;
• wherein the first surface is between the second surface and the first opening and the second surface is between the first surface and the second opening;
• wherein the first surface is a first distance from the first opening, the first distance being parallel to the long axis and being between 0.254 mm and 1.27 mm;
• wherein the projection includes an inner wall that couples the first surface of the projection to the second surface of the projection;
• wherein the inner wall of the projection has a first portion that is a second distance from the long axis, the second distance being orthogonal to the long axis;
• wherein the inner wall of the projection has a second portion that is a third distance from the long axis, the third distance being orthogonal to the long axis;
• wherein the third distance is greater than the second distance and the third distance is between 0.508 mm and 1.016 mm;
• wherein the third distance is greater than the second distance by a differential distance and the differential distance is between 0.127 mm and 0.381 mm;
• wherein the first surface is a fourth distance from the second surface, the fourth distance being parallel to the long axis and being between 0.254 mm and 5.588 mm;
• wherein the first portion of the projection projects inwardly from the wall of the aperture and towards the long axis by a fifth distance, the fifth distance being between 0.254 mm and 0.127 mm.