Variable angled locking screw
View Patent ↗A variable angle locking screw assembly that includes a plate material, a screw, and a washer at least partially located within the plate material, the washer and screw cooperating to create a wedge locking the screw in one of a plurality of axial and rotational positions, where the locked position may be undone and adjusted by manipulation of at least one of the screw and washer.
1. A locking screw assembly comprising:
a plate material having a through hole at least partially defined by a semispherical wall;
a first washer at least partially defining a first opening and being insertable into the through hole, the first washer including a widthwise dimension substantially greater than a thickness and comprising circumferentially spaced threaded wall segments, each pair of adjacent threaded wall segments being interposed by a circumferential discontinuity;
a second washer at least partially defining a second opening and being insertable into the through hole, the second washer includes a widthwise dimension substantially greater than a thickness;
a screw insertable into the through hole and including a threaded head that is configured to threadably mate with the threaded wall segments of the first washer, the screw further including a longitudinal threaded shaft extending from the threaded head; and
a driver configured to interact each circumferential discontinuity of the first washer to prevent rotation of the first washer while the screw is inserted into the through hole;
wherein the first opening and second opening are sized to allow throughput of the longitudinal threaded shaft; and
wherein the semispherical wall is sized to retain the first washer and the second washer within the through hole.
2. The locking screw assembly of claim 1 , wherein at least one of the first washer and the second washer includes a rounded circumferential surface interposing a top surface and a bottom surface.
3. The locking screw assembly of claim 1 , wherein a wall at least partially defining the first opening of the first washer is threaded.
4. The locking screw assembly of claim 3 , wherein a wall defining the second opening of the second washer is not threaded.
5. The locking screw assembly of claim 1 , wherein:
the longitudinal threaded shaft of the screw includes threads having a first pitch and a first thread depth;
the threaded head of the screw includes threads having a second pitch and a second thread depth;
the first pitch is greater than the second pitch; and
the first thread depth is greater than the second thread depth.
6. The locking screw assembly of claim 1 , wherein the second opening of the second washer is at least partially defined by a rounded over surface extending between a horizontal top surface and a wall of the second opening.
7. The locking screw assembly of claim 1 , wherein the second opening of the second washer is sized to inhibit throughput of the threaded head of the screw.