Offset rods, offset rod connectors, and related methods
Devices and methods that allow a rod to be offset in a relatively small amount of space are disclosed herein. In some embodiments, first and second offset rods can be joined by a plate-type connector having a reduced thickness suitable for insertion into a small space, e.g., between adjacent bone anchors. In some embodiments, first and second offset rods can be joined by a curved connector that conforms to adjacent bone anchors and likewise has a reduced thickness.
1 . A spinal connector, comprising:
a unitary body defined by a sidewall having a plurality of recesses formed therein, a first recess of the plurality of recesses being formed in an inferior surface of the body and a second recess of the plurality of recesses being formed in a superior surface of the body,
wherein a width of the body is defined by a width axis extending between lateral extents of the sidewall, a height of the body is defined by a height axis extending between anterior and posterior extents of the sidewall, and a thickness of the body is defined by a thickness axis extending between the superior surface and the inferior surface,
wherein the first recess is offset from the second recess along at least two of the width axis, the height axis, and the thickness axis, and a first longitudinal axis that passes through the first recess is parallel to a second longitudinal axis that passes through the second recess; and
wherein the body is configured to be rotatably tightened to one or more instruments disposed within the first recess or the second recess.
2 . The connector of claim 1 , wherein the body is configured to be rotatably tightened to the one or more instruments without a set screw being received within the body.
3 . The connector of claim 1 , wherein the first recess is offset from the second recess along the width axis and the height axis.
4 . The connector of claim 1 , wherein the superior surface includes a planar portion in which the second recess is formed and a concavely curved portion configured to abut a corresponding convexly curved portion of a receiver member of a bone anchor positioned superior to the superior surface.
5 . The connector of claim 4 , wherein the superior surface further comprises a convexly curved portion at an end opposite the planar portion.
6 . The connector of claim 5 , further comprising a first drive interface formed on the convexly curved portion.
7 . The connector of claim 6 , wherein the first drive interface is positioned on the superior surface opposite the first recess.
8 . The connector of claim 4 , wherein the inferior surface includes a planar portion in which the first recess is formed and a concavely curved portion configured to abut a corresponding convexly curved portion of a receiver member of a bone anchor positioned inferior to the inferior surface.
9 . The connector of claim 8 , wherein the inferior surface further comprises a convexly curved portion at an end opposite the planar portion.
10 . The connector of claim 9 , further comprising a second drive interface formed on the convexly curved portion.
11 . The connector of claim 10 , wherein the second drive interface is positioned on the inferior surface opposite the second recess.
12 . The connector of claim 8 , wherein a first-portion thickness of the body defined between the concavely curved portions of the superior and inferior surfaces is substantially equal to a second-portion thickness defined between the planar portions of the superior and inferior surfaces.
13 . The connector of claim 8 , wherein a first-portion thickness of the body defined between the concavely curved portions of the superior and inferior surfaces is smaller than a second-portion thickness of the body defined between the first recess and the superior surface of the body.
14 . The connector of claim 8 , further comprising a first spinal rod having a first diameter and a first central axis extending from the first recess, and a second spinal rod having a second diameter and a second central axis extending from the second recess.
15 . The connector of claim 14 , wherein the first spinal rod and the second spinal rod are permanently affixed to the connector.
16 . The connector of claim 15 , wherein a distance that the first spinal rod extends into the first recess is substantially equal to a first-portion thickness of the body defined between the concavely curved portions of the superior and inferior surfaces.
17 . The connector of claim 14 , wherein the body is rotationally symmetric about a central axis passing through a midpoint of the body.
18 . The connector of claim 1 , wherein the first recess terminates at an inferior termination that is inferior to the superior surface and the second recess terminates at a superior termination that is superior to the inferior surface.
19 . The connector of claim 18 , wherein the inferior termination of the first recess and a portion of the superior surface surrounding the second recess are substantially aligned along the thickness axis.
20 . The connector of claim 18 , wherein the superior termination of the second recess and a portion of the inferior surface surrounding the first recess are substantially aligned along the thickness axis.