Tissue retraction and vertebral displacement devices, systems, and methods for posterior spinal fusion
Devices for retracting tissue during a minimally-invasive, posterior spinal fusion procedure include a blade positionable along a passageway device connected to a connecting element implanted in a vertebra of the spine, such that the blade covers at least a portion of a longitudinal opening of the passageway device. The blade may be coupled to the passageway device by receiving the passageway device with a receiving portion. Systems for displacing the vertebrae of the spine include first and second extenders, the distal ends of each of which are configured to engage the connecting elements. Each extender may include a shaft configured to be securely engaged within a cage of the respective connecting element. The devices and systems of the present invention may be used in connection with an interbody fusion technique performed through an opening extending between the passageway devices, and an intermediate retractor blade may provide additional tissue retraction.
1 . A method of displacing vertebral bodies, comprising:
advancing a distal end of a first extender distally into a first passageway of a first passageway device until the first extender reaches a first received position, in which the first extender is received within the first passageway device along a first longitudinal axis of the first passageway device and in which a first engagement portion at the distal end of the first extender is securely engaged with a first connecting element, the first connecting element being connected to the first passageway device and affixed to a first vertebra of a spine; and
advancing a distal end of a second extender distally into a second passageway of a second passageway device until the second extender reaches a second received position, in which the second extender is received within the second passageway device along a second longitudinal axis of the second passageway device and in which a second engagement portion at the distal end of the second extender is securely engaged with a second connecting element, the second connecting element being connected to the second passageway device and affixed to a second vertebra of the spine;
displacing the first extender with respect to the second extender to induce displacement of the first and second connecting elements with respect to one another.
2 . The method of claim 1 , wherein the first connecting element includes a first pedicle screw and the second connecting element includes a second pedicle screw.
3 . The method of claim 2 , wherein the distal end of the first extender is securely engageable with the first connecting element by being receivable within a first cage of the first pedicle screw, and wherein the distal end of the second extender is securely engageable with the second connecting element by being receivable within a second cage of the second pedicle screw.
4 . The method of claim 3 , wherein the first cage is polyaxially coupled to the first pedicle screw, and wherein the second cage is polyaxially coupled to the second pedicle screw.
5 . The method of claim 4 , wherein, when the distal end of the first extender is securely engaged within the first cage, the distal end of the first extender locks polyaxial movement of the first cage with respect to the first pedicle screw, and when the distal end of the second extender is securely engaged within the second cage, the distal end of the second extender locks polyaxial movement of the second cage with respect to the second pedicle screw.
6 . The method of claim 1 , wherein the first extender includes a first shaft and the second extender includes a second shaft.
7 . A method of displacing vertebral bodies using a system for displacing vertebral bodies, the system including:
a first extender extending along a longitudinal dimension between a proximal end and a distal end of the first extender, the distal end of the first extender having a first engagement portion configured to securely engage a first connecting element anchorable to a first vertebra of the spine, the first engagement portion including a first rod portion extending transverse to the longitudinal dimension and configured to be received within a first cage of the first connecting element, the first cage being coupled to a first pedicle screw of the first connecting element for anchoring the first connecting element to the first vertebra;
a second extender extending along the longitudinal dimension between a proximal end and a distal end of the second extender, the distal end of the second extender having a second engagement portion configured to securely engage a second connecting element anchorable to a second vertebra of the spine, the second engagement portion including a second rod portion extending transverse to the longitudinal dimension and configured to be received within a second cage of the second connecting element, the second cage being coupled to a second pedicle screw of the second connecting element for anchoring the second connecting element to the second vertebra; and
a manipulation device engageable with the first and second extenders while the first and second rod portions extend towards one another, wherein the manipulation device is configured to displace the first and second vertebrae with respect to each other by inducing movement of the first extender with respect to the second extender when the first and second extenders are securely engaged with the anchored first and second connecting elements, respectively,
the method comprising:
anchoring the first pedicle screw of the first connecting element to the first vertebra of the spine;
anchoring the second pedicle screw of the second connecting element to the second vertebra of the spine;
securely engaging the first engagement portion of the first extender to the first connecting element such that the first rod portion of the first engagement portion is received within the first cage of the first connecting element and the first extender is offset laterally with respect to a central axis of the first cage;
securely engaging the second engagement portion of the second extender to the second connecting element such that the second rod portion of the second engagement portion is received within the second cage of the second connecting element and the second extender is offset laterally with respect to a central axis of the second cage; and
operating the manipulation device to move the first extender with respect to the second extender to thereby displace the first and second vertebrae with respect to each other along a cephalad/caudal dimension of the spine.
8 . The method of claim 7 , wherein the proximal end of each of the first and second extenders includes a connector for engagement by a manipulation device.
9 . The method of claim 8 , wherein the connector of the first extender is, with respect to the longitudinal dimension, on an opposite side of the first extender from the first rod portion; and wherein the connector of the second extender is, with respect to the longitudinal dimension, on an opposite side of the second extender from the second rod portion.
10 . The system method of claim 7 , wherein the first extender includes a first retractor blade and the second extender includes a second retractor blade, the first rod portion projecting outwardly from an inner face of the first retractor blade, and the second rod portion projecting outwardly from an inner face of the second retractor blade.
11 . The method of claim 7 , wherein the step of securely engaging the first engagement portion of the first extender to the first connecting element includes securing the first rod portion of the first extender to the first cage with a first set screw; and wherein the step of securely engaging the second engagement portion of the second extender to the second connecting element includes securing the second rod portion of the second extender to the second cage with a second set screw.
12 . The method of claim 7 , further comprising:
orienting a first retractor blade of the first extender and a second retractor blade of the second extender away from one another along the cephalad/caudal dimension of the spine.
13 . The method of claim 7 , further comprising inserting an interbody implant into an intervertebral space between the first and second vertebrae.
14 . The method of claim 13 , further comprising securing the spinal fusion rod to the first and second cages of the respective first and second connecting elements.