FASTENER RETENTION SYSTEM FOR SPINAL PLATES
A fastener retention system for retaining fasteners within apertures of an orthopedic plate includes a first pocket disposed between two of the apertures in the plate, a blocking member disposed between the two apertures and including a second pocket that forms a cavity with the first pocket, and a spring that expands from a compressed configuration within the first pocket to a decompressed configuration within the cavity.
1 . A fastener retention system for retaining fasteners within apertures of an orthopedic plate, comprising:
a first pocket disposed between two of the apertures in the plate;
a blocking member disposed between the two apertures and including a second pocket that forms a cavity with the first pocket; and
a spring that expands from a compressed configuration within the first pocket to a decompressed configuration within the cavity.
2 . The system of claim 1 , wherein the spring includes a height that is less than or equal to a depth of the first pocket when in the compressed configuration.
3 . The system of claim 1 , wherein the spring includes a height that is greater than a depth of the first pocket when in the decompressed configuration.
4 . The system of claim 1 , wherein the spring includes a plurality of flexible resilient members coupled by a plurality of hubs.
5 . The system of claim 1 , wherein the spring includes a radius of curvature in the decompressed configuration.
6 . The system of claim 1 , wherein the spring includes a central hub that contacts a surface of the first pocket in the compressed configuration and a surface of the second pocket in the decompressed configuration.
7 . The system of claim 1 , wherein the spring is further configured to bias the blocking member to protrude into at least one of the two apertures.
8 . The system of claim 1 , wherein the first pocket is disposed in a channel extending between the two apertures in the plate and includes a first depth D 1 .
9 . The system of claim 8 , wherein the blocking member is disposed in the channel and the second pocket includes a second depth D 2 .
10 . The system of claim 9 , wherein the spring is configured to compress to a first height H 1 that is less than or equal to D 1 when a first force is applied to the spring and expand to a second height H 2 that is greater than D 1 and less than or equal to the combined depth of D 1 and D 2 when the first force is released.
11 . The system of claim 10 , wherein the spring is further configured to engage with a portion of the blocking member when the first force is released and compress from a first length L 1 to a second length L 2 when a second force is applied to the blocking member.
12 . A system for bone fixation comprising:
an orthopedic plate having apertures configured to receive fasteners and a first pocket formed in a channel between two of the apertures;
a blocking member that slides in the channel and includes a second pocket, wherein the first and second pockets form a cavity between the blocking member and the orthopedic plate; and
a spring that expands from a compressed configuration, wherein a height of the spring is less than or equal to a depth of the first pocket, to a decompressed configuration, wherein the height of the spring is greater than the depth of the first pocket.
13 . The system of claim 12 , wherein a first portion of the spring is configured to engage a wall of the second pocket in the decompressed configuration.
14 . The system of claim 12 , wherein a second portion of the spring is configured to engage a wall of the first pocket in the decompressed configuration.
15 . The system of claim 12 , wherein the spring biases the blocking member towards a top surface of the orthopedic plate in the decompressed configuration.
16 . The system of claim 12 , wherein the spring biases the blocking member towards a rest position substantially equidistant from the two apertures in the decompressed configuration.
17 . The system of claim 12 , wherein the spring includes a radius of curvature in the decompressed configuration that is less than a radius of curvature in the compressed configuration.
18 . A method comprising:
inserting a spring into a first pocket in a channel of a plate;
inserting a blocking member having a second pocket into the channel of the plate;
positioning the blocking member to align the second pocket and the first pocket forming a cavity; and
expanding the spring to fill the cavity.
19 . The method of claim 18 , further comprising:
inserting a first screw into a first aperture adjacent to the first pocket to secure the plate to a vertebra;
positioning the blocking member towards a second aperture that is opposite the first aperture and adjacent to the first pocket using the first screw, wherein the spring compresses; and
decompressing the spring to bias the blocking member to align the second pocket and the first pocket.
20 . The method of claim 19 , further comprising:
inserting a second screw into the second aperture to secure the plate to the vertebra;
positioning the blocking member towards the first aperture using the second screw, wherein the spring compresses; and
decompressing the spring to bias the blocking member to align the second pocket and the first pocket.