Patent Description:
Common procedures for handling pain associated with intervertebral discs that have become degenerated due to various factors such as trauma or aging may include the use of pedicle screw fixation and/or intervertebral fusion for fusing one or more adjacent vertebral bodies. Generally, bilateral pedicle screw fixation, for example, with a rod construct, may be used to treat degenerative disc disease and a multitude of other spine pathologies as a standard of treatment to stabilize two or more adjacent vertebral bodies, for example, as an adjunct to spinal fusion.

Unfortunately, a number of iatrogenic pathologies are associated with pedicle screw fixation including, but not limited to, misplacement of screws, muscle/ligamentous disruption during insertion, adjacent segment disease due to superior adjacent facet violation by the inferior pedicle screw construct, increased procedural time, and/or instrumentation failure. There exists a clinical need for a fixation system and method that reduces the iatrogenic effects of a bilateral pedicle screw construct from a posterior approach while stabilizing two adjacent vertebral bodies that may be used as an adjunct to spinal fusion.

<CIT> describes an intradiscal implant known in the art.

The present invention relates a pedicle based fixation device as claimed hereafter.

In accordance with the application, pedicle-based devices, systems are provided. In particular, pedicle-based intradiscal fixation devices are provided, which may be used as a standalone device or may be used in conjunction with a traditional interbody fixation device. It is described but does not form part of the invention a method of fixation including inserting the device through the pedicle of an inferior vertebra, into the vertebral body of the inferior vertebra and securing the device to the vertebral body of the adjacent superior vertebra. The pedicle-based intradiscal fixation devices described herein may improve access-related morbidity while providing sufficient stabilization force for spinal fusion.

According to one embodiment, an implant for stabilizing an inferior vertebra and a superior vertebra includes a first member and a second member connected to the first member. The implant has a first, initial insertion orientation and a second, final implantation orientation different from the first, initial insertion orientation. The first member is configured to be inserted through a pedicle of the inferior vertebra and the second member is configured to engage bone of the superior vertebra in the second, final implantation orientation.

There are also described but do not form part of the invention methods of intradiscal fixation. A method for stabilizing an inferior vertebra and a superior vertebra may include: posteriorly accessing a spine of a patient; inserting an implant having a first member and a second member into a pedicle of the inferior vertebra in a first, initial orientation; inserting the first member of the implant into a vertebral body of the inferior vertebra; and modifying the implant into a second, final implantation orientation and inserting the second member of the implant into a vertebral body of the superior vertebra, wherein the implant traverses a disc or disc space between the inferior and superior vertebrae, and the second, final implantation orientation thereby fixates the inferior and superior vertebrae.

It is described an implant including a pedicle screw, a housing affixed to the pedicle screw, and an anchor moveably connected to the housing. The implant has a collapsed position whereby the anchor is positioned close to the pedicle screw, and the implant has an extended position whereby the anchor is moved away from or extended from the pedicle screw. The pedicle screw is configured to be inserted through a pedicle of the inferior vertebra in the collapsed position, and the anchor is configured to engage bone of the superior vertebra in the extended position.

The pedicle screw implant may include one or more of the of the following features. The pedicle screw may have a proximal end including a recess configured to receive an instrument for inserting the pedicle screw and a distal end configured to be inserted into the pedicle of the inferior vertebra. The pedicle screw may include one or more threads configured to engage bone. The housing may include a first portion configured to receive the pedicle screw and a second portion configured to retain the anchor therein. The anchor may be configured to move, pivot, or articulate relative to the pedicle screw. The anchor may have a proximal end configured to be received in the housing and a distal end configured to be inserted into a vertebral body of the superior vertebra in the extended position. The anchor may be curved between the proximal and distal ends. The anchor may be generally positioned perpendicular to the pedicle screw in the extended position. The anchor may include one or more tracks configured to engage corresponding tracks within the second portion of the housing, and thereby allow for movement of the anchor between the collapsed and extended positions.

According to another embodiment, the implant may include a curved outer tube and a curved inner tube positionable within the outer tube. The implant has a collapsed position whereby the inner tube is positioned inside the outer tube, and the implant has an extended position whereby the inner tube extends from the outer tube. The outer tube is configured to be inserted through a pedicle of the inferior vertebra in the collapsed position, and the inner tube is configured to engage bone of the superior vertebra in the extended position.

The tube implant may include one or more of the of the following features. The inner tube may include one or more ribs extending along the length of the tube configured to engage bone. The outer and inner tubes may be hollow and may be configured to receive bone cement therethrough. The implant may further include a separate segmented tube configured to advance the inner tube and stabilize the outer tube. The segmented tube may include a plurality of articulating links. Each of the links may include a joint, such as a ball and a socket configured to receive the ball of an adjacent link. The segmented tube may be encapsulated by the outer tube in the extended position.

According to another embodiment, the implant may include a screw portion and an anchor portion moveably coupled to the screw portion. The implant has a collapsed position whereby the anchor portion is positioned substantially in line with the screw portion, and the implant has an extended position whereby the anchor portion is extended away from the screw portion. The screw portion is configured to be inserted through a pedicle of the inferior vertebra in the collapsed position, and the anchor portion is configured to engage bone of the superior vertebra in the extended position.

The anchor implant may include one or more of the of the following features. The implant may further include a rod portion receivable in the screw portion. The implant may also include a push rod connected to a distal end of the screw portion by a first pin and connected to the anchor portion by a second pin. When the screw portion moves forward along the rod portion, the push rod may push forward and slide the anchor portion outward into the extended position. The rod portion may include one or more tracks configured to mate with corresponding tracks along the anchor portion, thereby facilitating movement of the anchor portion relative to the screw portion.

According to another embodiment, the implant includes a curved nail and a flexible screw moveable along the length of the nail. The implant has a first position whereby the nail is configured to be inserted into a pedicle of the inferior vertebra, a vertebral body of the inferior vertebra, and a vertebral body of the superior. The implant has a final position whereby the screw is inserted over the nail to rigidly lock the nail and screw together and provide resistance to pullout. The flexible screw may include one or more threads, and the flexible screw may have an open helical design with gaps between crests of the one or more threads.

According to another embodiment, the implant includes a body extending from a proximal end to a distal end, a pivotable head connected to the distal end of the body, and an actuator for moving the pivotable head between an inline position and a transverse position. The implant is configured to be inserted through a pedicle of the inferior vertebra and into the superior vertebra. The body may be made of a shape-memory material such that the body has a curved shape-memory orientation and a temporarily straight orientation. The body may include a first half and a second half. The first and second halves may be permitted to slide independent of one another. The first half may include one or more male portions and the second half may include one or more female portions configured to receive the one or more male portions of the first half. The male portion may include a first set of two opposed projections extending away from one another and configured to fit within a first set of two corresponding opposed recesses in the second half, and the second half may include a second set of two opposed projections extending toward one another and configured to fit within a second set of two corresponding opposed recesses within the male portion of the first half. The actuator may be a set screw or other suitable actuation mechanism. When the actuator presses against the first half of the body, the opposite end of the first half may in turn push on the pivotable head, thereby causing the head to pivot. Once the head fully pivots into the transverse position, the actuator may be configured to prevent movement of the first and second halves relative to each other, thereby causing the body to increase in stiffness.

It is also described but does not form part of the invention a method for stabilizing an inferior vertebra and a superior vertebra including one or more of the following steps: (<NUM>) posteriorly accessing a spine of a patient; (<NUM>) inserting an implant having a body having a first half and a second half slidable relative to one another, a pivotable head connected to the body, and an actuator configured to move the pivotable head into a pedicle of the inferior vertebra with the pivotable head in an inline orientation; (<NUM>) inserting the implant into a vertebral body of the inferior vertebra; (<NUM>) inserting the implant into a vertebral body of the superior vertebra, wherein the implant traverses a disc or disc space between the inferior and superior vertebrae; and (<NUM>) moving the pivotable head to a transverse orientation, thereby fixating the inferior and superior vertebrae. The body may be composed of a shape-memory material. The method may further include drawing the implant into a straight deployment tube such that the body is straightened within the tube, and deploying the implant from the deployment tube such that the body returns to a curved shape. The method may also include moving the pivotable head by actuating the actuator such that the actuator presses against the first half of the body and the first half in turn pushes on the pivotable head, thereby causing the head to pivot. Once the head fully pivots into the transverse orientation, the actuator may be configured to prevent movement of the first and second halves relative to each other, thereby causing the body to increase in stiffness.

According to another embodiment, the implant includes an inner core extending from a proximal end to a distal end, an outer segmented sheath positioned over the inner core, and a nut configured to compress the outer segmented sheath. The implant is configured to be inserted through a pedicle of the inferior vertebra and into the superior vertebra. The inner core may be made of a shape-memory material, and the inner core may have a curved shape-memory orientation and a temporarily straight orientation. The segmented sheath may include a plurality of links. The plurality of links may be configured to be arranged in a generally linear configuration or a curved configuration to mimic the shape of the inner core. The implant may include a proximal end cap and/or a distal end cap to prevent disassembly of the outer sheath from the inner core. The proximal end cap, if present, may include a plurality of outer threads configured to retain the nut. When the nut is moved forward distally and abuts the segmented sheath, the segmented sheath may be tightened between the nut and the distal end cap, thereby locking the outer segmented sheath.

Also described are kits including pedicle-based intradiscal fixation devices of varying types and sizes, interbody fusion devices of varying types and sizes, rods, fasteners or anchors, k-wires, insertion tools, and other components for performing the procedure.

A more complete understanding of the present invention, and the attendant advantages and features thereof, will be more readily understood by reference to the following detailed description when considered in conjunction with the accompanying drawings. The invention is depicted in particular in <FIG>, the remaining figures illustrate examples that are useful for understanding the invention.

Bilateral pedicle screw fixation has been used to treat degenerative disc disease and other spine pathologies. However, a number of iatrogenic pathologies are associated with pedicle screw fixation. The system may improve access-related morbidity while providing sufficient stabilization force for spinal fusion. Accordingly, embodiments of the present application are generally directed to devices, systems for pedicle-based intradiscal fixation of two adjacent vertebrae. The terms device, fixation device, and implant may be used interchangeably herein.

Referring now to <FIG>, a pedicle-based intradiscal fixation device <NUM> according to one embodiment is shown implanted into two adjacent vertebrae <NUM>, namely, a superior vertebra <NUM> and an inferior vertebra <NUM>. The not claimed method of fixation may include, for example, accessing the spine from the posterior and inserting the device <NUM> into the pedicle <NUM> of the inferior vertebra <NUM>. If necessary, bone may be removed from the inferior pedicle <NUM> and/or the vertebral body <NUM> in order to facilitate placement of the device <NUM>. The device <NUM> may be further advanced into the vertebral body <NUM> of the inferior vertebra <NUM>. As shown, the device <NUM> may be angled or directed toward the superior of the inferior body <NUM>, but it is also envisioned that the location and orientation of the device <NUM> may be selected by a surgeon. The device <NUM> may be configured to be inserted and secured to the vertebral body <NUM> of the adjacent superior vertebra <NUM>. Thus, the device <NUM> may traverse the disc and/or disc space <NUM> between the two vertebrae <NUM>. In this manner, the device <NUM> may be configured to be implanted into both vertebrae <NUM> from a posterior approach, thereby allowing for fusion of the adjacent vertebrae <NUM>. One or more pedicle-based devices <NUM> may be used alone or in conjunction with a traditional interbody fusion device. Although the method is shown with respect to a single inferior pedicle <NUM>, it will be appreciated that the other inferior pedicle (not shown) may also receive the same or a similar device. It will also be appreciated that the same or similar devices may also be used on adjacent or other levels.

Turning now to <FIG>, the pedicle-based intradiscal fixation device <NUM> is shown in more detail. The pedicle-based implant <NUM> may include a pedicle screw <NUM>, a housing <NUM> affixed to the pedicle screw <NUM>, and an anchor <NUM> moveably connected to the housing <NUM>. As best seen in <FIG>, the implant <NUM> has a collapsed configuration whereby the anchor <NUM> is positioned close to the pedicle screw <NUM>, thereby allowing the implant <NUM> to be inserted into the pedicle <NUM> of the inferior vertebra <NUM>, for example, in a minimally invasive manner. As shown in <FIG>, once inserted in the inferior vertebra <NUM>, the implant <NUM> has an expanded or extended configuration whereby the anchor <NUM> is moved away from the pedicle screw <NUM>, thereby allowing for the anchor <NUM> to be inserted into the superior vertebra <NUM>.

The pedicle screw <NUM> may have a body extending from a first end <NUM> to a second <NUM>. The first end <NUM> may be a proximal end and may include a recess <NUM> configured to receive an instrument for inserting the pedicle screw <NUM>. The first end <NUM> may have an enlarged head portion or may be otherwise configured (e.g., headless). The second end <NUM> may be a distal end configured to be inserted into the pedicle <NUM> of the inferior vertebra <NUM>. The second end <NUM> may have a distal tip that is blunt, pointed, or otherwise configured to engage bone. The body of the pedicle screw <NUM> may include one or more threads <NUM> along the entire length of the shaft or a portion thereof. The thread <NUM> may have a suitable angle, lead, pitch, etc. to enhance insertion and/or engagement with the bone. Although a pedicle screw <NUM> is exemplified in this embodiment, it will be appreciated that the pedicle screw <NUM> could be substituted with a bone anchor, nail, or other fixation device.

The housing <NUM> may be affixed to the pedicle screw <NUM>. The housing <NUM> may include a first portion <NUM> configured to receive the pedicle screw <NUM>. For example, the first portion <NUM> may have an opening extending therethrough configured to receive the shaft of the pedicle screw <NUM> in a position where the threads <NUM> are absent. The outer surface of the first portion <NUM> may be dimensioned to be smaller than the major diameter of the threads <NUM>. The housing <NUM> may be positioned centrally along the pedicle screw <NUM> or more towards the distal end <NUM>. The housing <NUM> may include a second portion <NUM> configured to retain the anchor <NUM>. The second portion <NUM> may include an opening configured to receive the anchor <NUM>, which is configured to move, slide, pivot, or articulate the anchor <NUM> relative to the screw <NUM>.

The anchor <NUM> may have a body extending from a first end <NUM> to a second end <NUM>. The first end <NUM> may be a proximal end and the second end <NUM> may be a distal end configured to be inserted into the vertebral body <NUM> of the superior vertebra <NUM>. The second end <NUM> may have a distal tip that is sharp, pointed, or otherwise configured to engage bone. The body of the anchor <NUM> may include one or more tracks <NUM> configured to engage corresponding tracks within the opening of the second portion <NUM> of the housing <NUM>. The one more mating tracks <NUM> may be provided to allow for movement of the anchor <NUM> between the collapsed and extended positions. For example, in the collapsed position, shown in <FIG>, the distal end <NUM> of the anchor <NUM> may be received in the housing <NUM>, and after a force is applied to the proximal end <NUM> of the anchor <NUM>, the anchor <NUM> moves into the extended position, shown in <FIG>, such that the proximal end <NUM> of the anchor <NUM> is received in the housing <NUM>. In the extended position, the anchor <NUM> may be generally positioned perpendicular to the pedicle screw <NUM> or the anchor <NUM> may be angled or otherwise oriented to engage the vertebral body <NUM> of the superior vertebra <NUM>. It is also envisioned that the anchor <NUM> could pivot in the housing <NUM> about a joint, such as a pin joint or hinge joint. Although a single anchor <NUM> is depicted in this embodiment, it will be appreciated that additional anchors <NUM> could be received in the housing <NUM>. Multiple anchor geometries may be used to facilitate stability, for example, one or more anchors <NUM> may be inserted into the anchor housing <NUM> with orientation variances in up to three planes.

Referring now to <FIG>, a pedicle-based intradiscal fixation device <NUM> according to another embodiment is shown. In <FIG>, the pedicle-based implant <NUM> is implanted into the inferior vertebra <NUM> in a collapsed position. In <FIG>, the pedicle-based implant is deployed to an expanded or extended position such that the implant <NUM> is implanted into the vertebral body <NUM> of the superior vertebra <NUM>. The method of fixation may be similar to the method described for device <NUM>. For example, the spine may be accessed posteriorly and the device <NUM> may be inserted into the pedicle <NUM> of the inferior vertebra <NUM>. If necessary, bone may be removed from the inferior pedicle <NUM> and/or the vertebral body <NUM> in order to facilitate placement of the device <NUM>. The device <NUM> may be further advanced into the vertebral body <NUM> of the inferior vertebra <NUM>. The device <NUM> may be configured to be inserted and secured to the vertebral body <NUM> of the adjacent superior vertebra <NUM>. Thus, the device <NUM> may traverse the disc and/or disc space <NUM> between the two vertebrae <NUM>. If desired, cement may be injected through the implant <NUM> to rigidly fixate the implant <NUM> to the superior vertebral body <NUM>.

Turning now to <FIG>, the pedicle-based intradiscal fixation device <NUM> is shown in more detail. The pedicle-based implant <NUM> may include two or more concentric tubes. In particular, the implant <NUM> may include a first tube or outer tube <NUM> and a second tube or inner tube <NUM> positionable within the outer tube <NUM>. As best seen in <FIG>, the implant <NUM> has a collapsed configuration whereby the inner tube <NUM> is positioned inside the outer tube <NUM>, thereby allowing the implant <NUM> to be inserted into the pedicle <NUM> of the inferior vertebra <NUM>, for example, in a minimally invasive manner. As shown in <FIG>, once inserted in the inferior vertebra <NUM>, the implant <NUM> has an expanded or extended configuration whereby the inner tube <NUM> extends from the outer tube <NUM>, thereby allowing for the inner tube <NUM> to be inserted into the superior vertebra <NUM>.

The first tube or outer tube <NUM> may have a body extending from a first end <NUM> to a second end <NUM>. The first end <NUM> may be a proximal end and the second end <NUM> may be a distal end configured to be inserted into the pedicle <NUM> of the inferior vertebra <NUM>. The outer tube <NUM> may be generally hollow and may be curved along its length. The second tube or inner tube <NUM> may have a body extending from a first end <NUM> to a second end <NUM>. The first end <NUM> may be a proximal end and the second end <NUM> may be a distal end configured to be inserted into the vertebral body <NUM> of the superior vertebra <NUM>. The second end <NUM> may have a distal tip that is blunt, sharp, or otherwise configured to engage bone. The second tube <NUM> may also have one or more ribs <NUM> extending along the length or a portion thereof of the tube <NUM> configured to engage bone. The inner tube <NUM> may be generally hollow and may be curved along its length. In an alternative embodiment, the inner tube <NUM> may be an anchor, keel, or other fixation device and is not necessarily hollow throughout.

In one embodiment, the implant <NUM> may be installed as follows. The concentric curved tubes <NUM>, <NUM> may be inserted into the pedicle <NUM> of the inferior vertebra <NUM>. An instrument drives the inner concentric tube <NUM> into the superior vertebral body <NUM>. Bone cement, such as polymethyl methacrylate (PMMA) or a suitable self-setting orthopedic cement composition, may be injected through the concentric curved tubes <NUM>, <NUM> to rigidly fixate the implant assembly to the superior vertebral body <NUM>. In addition or in the alternative, bone cement may be inserted through the superior vertebral body pedicle to rigidly fixate the implant assembly to the superior vertebral body <NUM>.

Referring now to <FIG>, a pedicle-based intradiscal fixation device <NUM> according to another embodiment is shown. The concentric curved tubes <NUM>, <NUM> may be the same as described for implant <NUM> with a separate segmented tube <NUM> configured to advance the inner tube <NUM> and stabilize the outer tube <NUM>. The segmented tube <NUM> may include a plurality of articulating members or links <NUM> that act like puzzle pieces. The plurality of links <NUM> may be arranged in a generally linear configuration, as shown in <FIG>, or may be curved, as shown in <FIG>, for example, to mimic the shape of the outer tube <NUM>.

As best seen in <FIG>, each link <NUM> extends from a first end <NUM> to a second end <NUM>. In this case, either the first end <NUM> or the second end <NUM> of a first link <NUM> may be inserted into the outer tube <NUM>. In the embodiment shown, eight links <NUM> are connected such that the second end <NUM> of a given link <NUM> connects to the first end <NUM> of the next link <NUM> in the chain. Although it will be appreciated that any number of links <NUM> may be selected. Each of the links <NUM> are connected and able to articulate about a joint <NUM>. In this embodiment, the first end <NUM> of each link <NUM> includes a ball <NUM> and the second end <NUM> of each link <NUM> includes a socket <NUM> configured to receive the ball <NUM> of an adjacent link <NUM>. Accordingly, the socket <NUM> in the second end <NUM> of a given link <NUM> connects to the ball <NUM> of the first end <NUM> of the next link <NUM> in the chain. In this manner, each link <NUM> is able to articulate relative to the next link <NUM>, thereby forming a curved segmented tube <NUM>. Although a ball and socket joint <NUM> is exemplified in this embodiment, it will be appreciated that other suitable joints could be selected, such as pin joints, pivot joints, hinge joints or the like. It will also be appreciated that the locations of the ball <NUM> and socket <NUM> could be reversed on each link <NUM> or otherwise configured.

In one example, the implant <NUM> may be installed as follows. The concentric curved tubes <NUM>, <NUM> may be inserted into the pedicle <NUM> of the inferior vertebra <NUM>. The articulatable puzzle pieces or links <NUM> of the segmented tube <NUM> may be impacted, for example, through a straight instrument connected to the proximal end <NUM> of the concentric tubes <NUM>, <NUM>. For example, the straight links <NUM> may be impacted one by one into the outer curved tube <NUM>. The links <NUM> articulate and lock into a curved orientation during impaction. As additional links <NUM> are impacted, the inner tube <NUM> is incrementally advanced past the distal end <NUM> of the outer curved tube <NUM> and into the superior vertebral body <NUM>. Thus, the segmented tube <NUM> drives the inner concentric tube <NUM> into the superior vertebral body <NUM>. The segmented tube <NUM> may be configured to be encapsulated in the outer curved tube <NUM>, thereby adding rigidity to the outer tube <NUM>. If desired, bone cement may be injected through the concentric curved tubes <NUM>, <NUM> and/or separately added to the superior vertebra <NUM> as described previously. In an alternative embodiment, if cement is not needed to be dispensed through the device <NUM>, the segmented tube <NUM> may be solid and does not need to be hollow throughout.

Turning to <FIG>, alternative locking geometries may be used for the links <NUM>, for example, to improve rigidity of the final construct. It will be appreciated that all of the links <NUM> for a given segment are shown identical, but it is envisioned that different links could be provided through the chain. In one embodiment shown in <FIG>, the second end <NUM> of the link <NUM> includes a protrusion or tab <NUM> configured to engage a corresponding recess <NUM> in an adjacent link <NUM>. The tab <NUM> may be positioned, for example, below the socket <NUM> of the link <NUM> and the recess <NUM> may be positioned below the ball <NUM>. In the straight configuration shown in <FIG>, the tabs <NUM> are not engaged with the recesses <NUM>. In the curved configuration shown in <FIG>, the tabs <NUM> are locked in the respective recesses <NUM> of the adjacent links <NUM>. In the embodiment shown in <FIG>, in addition to tab <NUM>, a bump <NUM> is positioned above the recess <NUM> and an additional protrusion or spike <NUM> is provided. The bump <NUM> may be received in a corresponding recess <NUM> positioned adjacent to the tab <NUM>, thereby further securing adjacent links <NUM> together. An upper portion of the second end <NUM> above the socket <NUM> may include a protrusion or spike <NUM>, which is receivable in one or more corresponding notches <NUM> in the body of an adjacent link <NUM>. In this manner, the spike <NUM> may act as a ratchet as it moves through one or more notches <NUM> as the links <NUM> articulate. In the curved configuration shown in <FIG>, the spike <NUM> may engage with a corresponding protrusion or spike <NUM> between two or more notches <NUM>. In the embodiment shown in <FIG>, in addition to the features in <FIG>, the upper portion above the socket <NUM> may further includes a curved protrusion <NUM> adjacent to spike <NUM>, which may be configured to further lock the link <NUM> to an adjacent link <NUM>. For example, the protrusion <NUM> may be received in one of the notches <NUM> in the body of an adjacent link <NUM>. One or more of the locking geometries may be used for one or more of the links <NUM>, for example, to improve rigidity of the segmented tube <NUM>.

Turning now to <FIG>, a pedicle-based intradiscal fixation device <NUM> according to another embodiment is shown. The not claimed method of fixation may be similar to the not claimed methods described herein for other devices. For example, the spine may be accessed posteriorly and the device <NUM> may be inserted into the pedicle <NUM> of the inferior vertebra <NUM> in a collapsed configuration. The device <NUM> may be further advanced into the vertebral body <NUM> of the inferior vertebra <NUM>. The device <NUM> may then be expanded or extended into the vertebral body <NUM> of the adjacent superior vertebra <NUM>. Thus, the device <NUM> may traverse the disc and/or disc space <NUM> between the two vertebrae <NUM>.

Referring to <FIG>, the pedicle-based intradiscal fixation device <NUM> is shown in more detail. The pedicle-based implant <NUM> may include a screw portion <NUM> and an anchor portion <NUM> moveably connected to the screw portion <NUM>. As best seen in <FIG>, the implant <NUM> has a collapsed configuration, thereby allowing the implant <NUM> to be inserted into the pedicle <NUM> of the inferior vertebra <NUM>, for example, in a minimally invasive manner. As shown in <FIG>, once inserted in the inferior vertebra <NUM>, the implant <NUM> has an expanded or extended configuration whereby the anchor portion <NUM> is extended outwardly, thereby allowing for the anchor portion <NUM> to be inserted into the superior vertebra <NUM>.

The screw portion <NUM> may have a body extending from a first end <NUM> to a second <NUM>. The first end <NUM> may be a proximal end and may include a recess <NUM> configured to receive an instrument for inserting the implant <NUM>. The first end <NUM> may have an enlarged head portion or may be otherwise configured (e.g., headless). The second end <NUM> may be a distal end coupled to the moveable anchor portion <NUM>. The screw portion <NUM> may be generally hollow and may be configured to slide along a rod portion <NUM>. The body of the pedicle screw <NUM> may include one or more threads <NUM> along the entire length of the shaft or a portion thereof. The thread <NUM> may have a suitable angle, lead, pitch, etc. to enhance insertion and/or engagement with the bone. Although a threaded screw portion <NUM> is exemplified in this embodiment, it will be appreciated that it could be substituted with ribs, teeth, or other bone fixation mechanisms.

The anchor portion <NUM> may have a body extending from a first end <NUM> to a second end <NUM>. The first end <NUM> may be a proximal end and the second end <NUM> may be a distal end configured to be inserted into the vertebral body <NUM> of the superior vertebra <NUM>. The second end <NUM> may have a distal tip that is sharp, pointed, or otherwise configured to engage bone. The anchor portion <NUM> may be curved or otherwise contoured. The anchor portion <NUM> may have sufficient length such that the anchor <NUM> may span from the inferior vertebra <NUM> to the superior vertebra <NUM> through the affected disc space <NUM>. In the extended position, the anchor portion <NUM> may be generally positioned perpendicular to the screw portion <NUM> or the anchor portion <NUM> may be angled or otherwise oriented to engage the vertebral body <NUM> of the superior vertebra <NUM>.

As best shown in <FIG>, an articulation assembly <NUM> is configured to articulate the anchor portion <NUM> from the collapsed position to the extended position. The articulation assembly <NUM> may include a push rod <NUM> connected to the distal end <NUM> of the screw portion <NUM> by a first pin <NUM> and connected to the anchor portion <NUM> by a second pin <NUM>. When the screw portion <NUM> moves forward along the rod portion <NUM>, the push rod <NUM> pushes forward and slides the anchor portion <NUM> outward. The anchor portion <NUM> and rod portion <NUM> may include one or more corresponding tracks configured to facilitate the movement. An instrument <NUM> may be provided to articulate the anchor portion <NUM>. For example, as shown in <FIG>, the instrument <NUM> may be affixed to the head of the screw portion <NUM>. An inner rod <NUM> of the instrument <NUM> may be inserted through the screw portion <NUM> and may couple to the rod portion <NUM> of the implant <NUM>. When the screw portion <NUM> is moved forward along the inner rod <NUM> and the rod portion <NUM> and/or the inner rod <NUM> is withdrawn from the screw portion <NUM>, the anchor portion <NUM> articulates outward into the extended position shown in <FIG>. Once in its final extended position, one or more locking members may be used to lock the articulated implant <NUM>, thereby facilitating resistance to toggle. For example, a threaded locking cap <NUM> may be inserted into the recess <NUM> of the implant <NUM> to lock the anchor portion <NUM> in the extended position.

Turning now to <FIG>, a pedicle-based intradiscal fixation device <NUM> according to another embodiment is shown. The not claimed method of fixation may be similar to the not claimed methods described herein for other devices. For example, the spine may be accessed posteriorly and the device <NUM> may be inserted into the pedicle <NUM> of the inferior vertebra <NUM> in a first or initial configuration, shown in <FIG>. The device <NUM> may be further advanced into the vertebral body <NUM> of the inferior vertebra <NUM> and into the vertebral body <NUM> of the adjacent superior vertebra <NUM>. Thus, the device <NUM> may traverse the disc and/or disc space <NUM> between the two vertebrae <NUM>. The device <NUM> may be manipulated into a second or final configuration by positioning a flexible screw <NUM> over a curved nail <NUM>, as shown in <FIG>.

Referring to <FIG>, the pedicle-based intradiscal fixation device <NUM> is shown in more detail. The pedicle-based implant <NUM> may include a nail <NUM> and a screw <NUM> moveable along the length of the nail <NUM>. As best seen in <FIG>, the implant <NUM> has an initial configuration, whereby the nail <NUM> may be inserted into the pedicle <NUM> of the inferior vertebra <NUM>, the vertebral body <NUM> of the inferior vertebra <NUM>, and the vertebral body <NUM> of the superior vertebra <NUM>. As shown in <FIG>, the implant <NUM> has a final configuration whereby the screw <NUM> is inserted over the nail <NUM> to rigidly lock the segments and provide resistance to pullout.

The nail <NUM> may have a body extending from a first end <NUM> to a second end <NUM>. The first end <NUM> may be a proximal end and the second end <NUM> may be a distal end configured to be inserted into the vertebral body <NUM> of the superior vertebra <NUM>. The second end <NUM> may have a distal tip that is sharp, pointed, or otherwise configured to engage bone. The nail <NUM> may have one or more helical channels or grooves <NUM> configured to engage bone and/or facilitate movement of the screw <NUM> when inserted over the nail <NUM>. In other words, the nail <NUM> may be threaded along its entire length or a portion thereof. The nail <NUM> may be curved or otherwise contoured along its length. For example, the nail <NUM> may have a first straight portion near the proximal end <NUM>, a curved portion, and then a second straight portion near the distal end <NUM>. The nail <NUM> may be sufficiently rigid such that it maintains its shape as the screw <NUM> is inserted thereon. The nail <NUM> may have a sufficient length such that nail <NUM> may span from the pedicle <NUM> to the inferior vertebra <NUM> and to the superior vertebra <NUM> through the affected disc space <NUM>.

Alternative versions of the screw <NUM> are shown in <FIG>. The screw <NUM> may have a body extending from a first end <NUM> to a second <NUM>. The first end <NUM> may be a proximal end and may include a recess <NUM> configured to receive an instrument for inserting the screw <NUM>. As best seen in <FIG>, the first end <NUM> may have an enlarged head portion <NUM>. Alternatively, as shown in <FIG>, the first end <NUM> may be headless. The second end <NUM> may have a distal tip that is blunt, pointed, or otherwise configured to engage bone. The screw <NUM> may be generally hollow and may be configured to receive the nail <NUM> therein. The screw <NUM> may be formed by one or more threads <NUM>. The thread <NUM> may be an open helical spring with gaps between each of the crests of the thread <NUM>. The thread <NUM> may have a suitable angle, lead, pitch, etc. to enhance insertion and/or engagement with the bone.

As best seen in <FIG>, the flexible screw <NUM> may have a generally linear or straight configuration and may be bent into a generally curved configuration. Due to the open geometry of the thread <NUM>, the screw <NUM> may be flexible such that it is capable of bending easily to conform to the curved geometry of the nail <NUM>. Accordingly, after the threaded curved nail <NUM> is inserted into the inferior pedicle <NUM> through to the superior vertebral body <NUM>, spanning the intradiscal space <NUM>, the flexible screw <NUM> may be threaded over the threaded curved nail <NUM> to rigidly lock the segments and provide resistance to pullout.

Turning now to <FIG>, a pedicle-based intradiscal fixation device or anchor <NUM> according to another embodiment is shown. The not claimed method of fixation may be similar to the not claimed methods described herein for other devices. For example, the spine may be accessed posteriorly and the device <NUM> may be inserted into the pedicle <NUM> of the inferior vertebra <NUM> in a first or inline configuration. The device <NUM> may be further advanced into the vertebral body <NUM> of the inferior vertebra <NUM>. The device <NUM> may be positioned into the vertebral body <NUM> of the adjacent superior vertebra <NUM>, and then the head <NUM> may be extended or articulated into a second or transverse configuration. Thus, the device <NUM> may be incorporated into the inferior pedicle <NUM> which allows the anchor <NUM> to span from inferior to superior vertebrae <NUM>, <NUM> through the affected disc space <NUM>.

Referring to <FIG>, the pedicle-based intradiscal fixation device or anchor <NUM> is shown in more detail. The pedicle-based implant or anchor <NUM> may include a body <NUM> extending from a first end or proximal end <NUM> to a second end or distal end <NUM>, a pivotable head <NUM> connected to the distal end <NUM> of the body <NUM>, and an actuator <NUM> for moving the pivotable head <NUM> between an inline or contracted position and a transverse or extended position. The body <NUM> may be composed of an elastic or flexible material, such as polyetheretherketone (PEEK). In one embodiment, the body <NUM> is made of a shape-memory material. For example, the body <NUM> may be composed of a suitable biocompatible polymer, metal, alloy, or other suitable material configured to impart shape memory to the body <NUM> of the implant <NUM>. The body <NUM> may have a generally curved or bent shape memory but is also able to be temporarily straightened or modified into a temporary shape.

In order to deploy the anchor <NUM>, the anchor <NUM> may be first drawn into a deployment tube <NUM> (e.g., shown in <FIG>). When the anchor <NUM> is positioned within a straight deployment tube <NUM>, the anchor <NUM> is unbent and held in a straight orientation inside the deployment tube <NUM>. In other words, the anchor <NUM> is able to temporarily mimic the shape of the deployment tube <NUM>. The anchor <NUM> may be able to flex into a straight orientation due to the elastic properties of the material (e.g., PEEK) as well as the cross sectional area of the anchor <NUM>. After the anchor <NUM> is deployed from the deployment tube <NUM>, the implanted anchor <NUM> returns to its original curved or bent shape.

The pedicle-based implant or anchor <NUM> may include a multi-component body <NUM>. The body <NUM> may include a first half, inner half, or upper portion <NUM> and a second half, outer half, or lower portion <NUM>. The first half <NUM> and/or second half <NUM> may include a plurality of serrations, teeth, or friction enhancing surfaces <NUM>, for example. The serrations or teeth <NUM> may extend along the entire length of the first half <NUM> and/or the second half <NUM> or a portion thereof. The serrations or teeth <NUM> may be configured to grip the bone of the vertebrae <NUM>. In the embodiment shown in <FIG>, teeth <NUM> are provided along an upper surface of the first half <NUM> and the lower portion <NUM> has a smooth outer body. The smooth outer body may be configured to ease insertion into the bone. In the embodiment shown in <FIG>, the first and second halves <NUM>, <NUM> each have teeth <NUM> extending along the outer surfaces, respectively. Although the teeth <NUM> and smooth surfaces are exemplified, it will be appreciated that other configurations may be used.

As best seen in the cross-section shown in <FIG>, the first half <NUM> may include one or more male portions <NUM> and the second half <NUM> may include a recess with one or more female portions <NUM> configured to receive the male portions <NUM> of the first half <NUM>. For example, the male portion <NUM> may include a first set of two opposed projections <NUM> extending away from one another and configured to fit within a first set of two corresponding opposed recesses <NUM> in the second half <NUM>. In addition, the second half <NUM> may include a second set of two opposed projections <NUM> extending toward one another and configured to fit within a second set of two corresponding opposed recesses <NUM> within the male portion <NUM> of the first half <NUM>. In this manner, the two halves <NUM>, <NUM> may be keyed together but are permitted to slide independent of each other. Unlike a solid anchor (e.g., a solid PEEK anchor) that would be unable to flex into a straight orientation without plastically deforming, the two halves <NUM>, <NUM> of the anchor <NUM> are able to elastically flex into a straight orientation without deforming and when the anchor <NUM> is deployed, the anchor <NUM> is able to resume its original bent shape.

As best seen in the cross-sectional view of <FIG>, the body <NUM> may include a center canal or opening <NUM>, which may be used to send the anchor <NUM> over a bent guide wire that has already been deployed through the pedicle <NUM> and up into the superior vertebral body <NUM>. Alternatively, or in addition, the canal or opening <NUM> may be configured to contain a curved piece of Nitinol or other shape memory material in order to increase the bend rigidity of the construct.

The proximal end <NUM> of the anchor <NUM> may include a plurality of outer threads or an outer threaded portion <NUM>. The outer threaded portion <NUM> may be configured to connect to an insertion instrument, for example. The proximal end <NUM> may also include a plurality of inner threads or an inner threaded portion <NUM>. The inner threaded portion <NUM> may be configured to receive a threaded actuator <NUM>. The distal end <NUM> of the body <NUM> may connect to the pivoting head <NUM>. For example, the second half <NUM> may connect to the pivoting head <NUM> with a pin <NUM>. The anchor <NUM> may include the pivoting head <NUM> in order to secure the anchor <NUM> into the superior vertebral body <NUM> after the anchor <NUM> has been deployed. The pivoting head <NUM> may have a tip that is conical, pointed, or otherwise configured to engage bone. As best seen in <FIG>, the pivoting head <NUM> has a first position or inline orientation, which is generally aligned with the curvature of the body <NUM> of the anchor <NUM>. When constrained by a straight deployment tube <NUM>, the head <NUM> and body <NUM> are aligned along the same longitudinal axis. As best seen in <FIG>, the pivoting head <NUM> has a second position or transverse orientation, which is generally angled or transverse to the body <NUM> of the anchor <NUM>.

The head <NUM> may be actuated, for example, by turning threaded actuator <NUM>, such as a set screw, at the pedicle end <NUM> of the anchor <NUM>. As shown in <FIG>, the actuator <NUM> is positioned within the body <NUM> and is configured to press against the proximal end of the first half <NUM>. As the actuator <NUM> pushes on the inner anchor half <NUM>, the distal end of the first half <NUM> in turn pushes on the anchor head <NUM>, thereby causing the head <NUM> to pivot about the pin <NUM>. As shown in <FIG>, when the first half <NUM> is translated forward, the distal end of the first half <NUM> presses against a cam surface <NUM> on a portion of the head <NUM>. The head <NUM> pivots about the pin <NUM>, thereby providing the head <NUM> into the extended or deployed condition. Once the head <NUM> fully pivots into place the actuator <NUM> also prevents movement of the halves <NUM>, <NUM> relative to each other, and thereby causes the anchor <NUM> to increase in its bending stiffness.

Turning now to <FIG>, a pedicle-based intradiscal fixation device or anchor <NUM> according to another embodiment is shown. The not claimed method of fixation may be similar to the not claimed methods described herein for other devices. For example, the spine may be accessed posteriorly and the device <NUM> may be inserted into the pedicle <NUM> of the inferior vertebra <NUM>. The device <NUM> may be further advanced into the vertebral body <NUM> of the inferior vertebra <NUM>. The device <NUM> may be positioned into the vertebral body <NUM> of the adjacent superior vertebra <NUM>. Thus, the device <NUM> may be incorporated into the inferior pedicle <NUM> which allows the anchor <NUM> to span from inferior to superior through the affected disc space <NUM>.

Referring to <FIG>, the pedicle-based intradiscal fixation device or anchor <NUM> is shown in more detail. The pedicle-based implant or anchor <NUM> may include an inner core <NUM> extending from a first end or proximal end <NUM> to a second end or distal end <NUM>, a segmented outer sheath <NUM> positioned over the core <NUM>, an optional proximal end cap <NUM> and a distal end cap <NUM> configured to secure the assembly, and a threaded component or nut <NUM> configured to compress the segmented sheath <NUM>. The inner core <NUM> may include an elongate body with a generally cylindrical shape or may be of another suitable shape or cross-dimension. The inner core <NUM> may be composed of an elastic or flexible material, such as The body <NUM> is made of a shape-memory material. For example, the core <NUM> may be composed of a suitable biocompatible polymer, metal, alloy, or other suitable material configured to impart shape memory. The inner core <NUM> may have a generally curved or bent shape memory but is also able to be temporarily straightened or modified into a temporary shape.

The segmented outer sheath <NUM> may be the same or similar to the segmented tubes <NUM> described herein. The segmented sheath <NUM> may include a plurality of articulating members, linking segments, or links <NUM>. The plurality of links <NUM> may be arranged in a generally linear configuration or may be curved, for example, to mimic the shape of the inner core <NUM>. The sheath <NUM> may be made from any suitable type of biocompatible material. The anchor <NUM> may include proximal end cap <NUM> and distal end cap <NUM> to prevent the sheath <NUM> from disassembling from the inner core <NUM>. The proximal end cap <NUM> may include a plurality of outer threads or an outer threaded portion <NUM> configured to retain the nut <NUM>. The nut <NUM> may have an inner threaded portion configured to mate with the outer threaded portion <NUM> of the cap <NUM>. The nut <NUM> may be threaded and moved forward distally to tighten the segmented sheath <NUM> between the nut <NUM> and the distal cap <NUM>.

As best seen in <FIG>, the nut <NUM> is in a first position with a gap between the end of the nut <NUM> and the proximal end of the segmented sheath <NUM>. In the first unlocked position, the inner core <NUM> and outer sheath <NUM> are permitted to straighten, for example, when loaded inside the deployment tube <NUM> and/or curve freely into the shape memory of the inner core <NUM> when not constrained. As best seen in <FIG>, the nut <NUM> is advanced forward on the threaded portion <NUM> of the cap <NUM> such that the nut <NUM> is moved to a second position. In the second locked position, the nut <NUM> presses against the proximal end of the outer sheath <NUM>, thereby compressing the outer sheath <NUM>, stiffening the links <NUM> of the outer sheath <NUM>, and preventing the outer sheath <NUM> and the entire construct from unbending. In other words, the anchor <NUM> is locked in the curved or bent position shown and is unable to straighten.

In order to deploy the anchor <NUM>, the anchor <NUM> may be first drawn into a deployment tube <NUM>. Due to the super elasticity of the material of the inner core <NUM> (e.g., Nitinol), the anchor <NUM> is configured to unbend and be held in the straight orientation inside the straight deployment tube <NUM>. After deployment from the tube <NUM>, the core <NUM> will resume its original curved or bent shape. After the core <NUM> has been deployed, the segmented sheath <NUM> may be deployed over the core <NUM>. The mating surfaces of the linking segments <NUM> may have specific angled cuts that allowed the segments <NUM> to approximate the curve of the core <NUM> as the segments <NUM> are impacted over the core <NUM>. In the embodiment shown, proximal cap <NUM> with outer threads <NUM> may be attached over the top of the core <NUM>. Alternatively, the pedicle end <NUM> of the core <NUM> may have the threads directly machined into the core <NUM>. In this configuration, the proximal cap <NUM> may be omitted. The threads <NUM> are configured to retain nut <NUM>. When nut <NUM> is moved forward toward the distal end <NUM>, the segmented sheath <NUM> is compressed. This compression stiffens the anchor construct and prevents unbending. In another embodiment, the outer sheath <NUM> and inner core <NUM> may be drawn and deployed together at the same time.

Turning now to <FIG>, a pedicle-based intradiscal fixation device or anchor <NUM> according to another embodiment is shown. The method of fixation may be similar to the methods described herein for other devices. For example, the spine may be accessed posteriorly and the device <NUM> may be inserted into the pedicle <NUM> of the inferior vertebra <NUM>. The device <NUM> may be further advanced into the vertebral body <NUM> of the inferior vertebra <NUM>. The device <NUM> may be positioned into the vertebral body <NUM> of the adjacent superior vertebra <NUM>. Thus, the device <NUM> may be incorporated into the inferior pedicle <NUM> which allows the anchor <NUM> to span from inferior to superior through the affected disc space <NUM>.

Referring to <FIG>, the pedicle-based intradiscal fixation device or anchor <NUM> is shown in more detail. The pedicle-based implant or anchor <NUM> may include an elongate body <NUM> extending from a first end or proximal end <NUM> to a second end or distal end <NUM>. The elongate body <NUM> may have a generally rectangular profile. Although the body <NUM> is shown to be rectangular in nature in this embodiment, it could also exist in uniquely different profiles as well. The body <NUM> may be composed of an elastic or flexible material, such as Nitinol. The body <NUM> may be composed of a suitable biocompatible polymer, metal, alloy, or other suitable material configured to impart shape memory. The body <NUM> may have a generally curved or bent shape memory with the ability to temporarily change shape. The proximal end <NUM> of the body <NUM> may include a threaded portion <NUM>. The threaded portion <NUM> may be configured to engage an insertion instrument or other suitable instrument. The distal end <NUM> may comprise a pointed tip, blunt tip, or may be otherwise suitably configured to pierce and/or engage bone. The surfaces of the body <NUM> may be generally smooth to enhance insertion and/or may include teeth or other features to engage the bone.

In order to deploy the anchor <NUM>, the anchor <NUM> may be first drawn into the deployment tube <NUM>. Due to the super elasticity of the material of the body <NUM>, the anchor <NUM> can unbend and be held in a straight orientation inside the deployment tube <NUM>. During deployment from the tube <NUM>, the body <NUM> will resume its original bent or curved shape. The ability of the anchor <NUM> to resume its original shape may be due, for example, to the cross sectional area of the body <NUM> and/or the type of shape-memory material.

Iatrogenic adjacent segment disease and other surgical issues have been attributed to pedicle screw fixation previously. This intradiscal fixation devices and not claimed methods described herein may obviate the need for pedicle screw fixation while potentially avoiding their iatrogenic effects. Traditional techniques may require multiple incisions for even minimally invasive pedicle screw fixation. The pedicle-based intradiscal fixation devices described herein may provide better stability in flexion, extension, and/or axial rotation compared with other anchor type fixation methods used in the anterior or lateral approaches. Compared with an anterior/lateral anchor or screw and plate method, the pedicle-based intradiscal approach may be performed from a posterior approach, avoiding potential disruption of vasculature or nerve roots found in the anterior and/or lateral approaches.

Claim 1:
An intradiscal implant (<NUM>; <NUM>) for stabilizing an inferior vertebra (<NUM>) and a superior vertebra (<NUM>), the intradiscal implant comprising: a body (<NUM>) extending from a proximal end (<NUM>) to a distal end (<NUM>), a pivotable head (<NUM>) connected to the distal end (<NUM>) of the body (<NUM>), and an actuator (<NUM>) for moving the pivotable head (<NUM>) between an inline position and a transverse position, wherein the intradiscal implant (<NUM>; <NUM>) is configured to be inserted through a pedicle (<NUM>) of the inferior vertebra (<NUM>) and into the superior vertebra (<NUM>), wherein the body (<NUM>) is made of a shape-memory material, and wherein the body (<NUM>) has a curved shape-memory orientation and a temporarily straight orientation, wherein the body (<NUM>) includes a first half (<NUM>) and a second half (<NUM>), wherein the first half (<NUM>) includes one or more male portions (<NUM>) and the second half (<NUM>) includes one or more female portions (<NUM>) configured to receive the one or more male portions (<NUM>) of the first half (<NUM>), so that the first and the second halves (<NUM>, <NUM>) are keyed together but are permitted to slide independent of each other.