DEVICE COMPRISING AN EXPANDABLE IMPLANT AND ANCHOR ELEMENT FOR FIXATION INTO A VERTEBRAL PEDICLE - Patent application

Abstract

A device for expanding a vertebra. The device includes an expandable implant and a pedicle anchor. The pedicle anchor includes at least one anchor element movably coupled to the anchor body. An actuator is movable within the anchor body to deploy the anchor element into engagement with the pedicle. The anchor element may deploy in a plane with the tissue support skis of the expandable implant. The actuator may be a rod including knuckles or cams. The tissue support skis may be recessed from the outer profile of the device. The struts of the expandable implant may be angled toward the tissue support skis in the insertion configuration. The device may be elliptical in shape and provide means for rotating the expandable implant relative to the pedicle anchor and for preventing migration of the expandable implant in a predetermined orientation. A method of deploying the device is also disclosed.

Description

[Technical field]

[0001] Priority claim This application claims priority to and all benefit of U.S. Provisional Patent Application No. 63 / 291,712, filed December 20, 2021, the entire contents of which are incorporated herein by reference. [Background technology]

[0002] A common cause of back pain is vertebral compression fractures, in which a weakened or damaged vertebral body loses height or collapses. Vertebral body weakening may result from acute injury or, more commonly, from degenerative changes such as osteoporosis. Compression fractures often appear on lateral radiographs as a wedge-shaped deformity with loss of height anteriorly.

[0003] A vertebral augmentation procedure is a treatment modality that elevates or restores the height of a vertebral body and stabilizes it at the elevated or restored height. One method of doing so involves deploying an implant within the vertebral body. The implant is configured to expand to elevate or restore the height of the vertebral body. The implant can remain within the vertebral body to promote and maintain the structural integrity of the vertebral body at the elevated or restored height. An exemplary implant and system for doing so is described, among other things, in commonly owned U.S. Patent No. 7,846,206, issued Dec. 7, 2010, the entire contents of which are incorporated herein by reference, and sold by Stryker Corporation (Kalamazoo, Michigan) under the trade name SpineJack.

[0004] The SpineJack implant, as the name implies, includes at least two pairs of supports (or tissue support skis) configured to move the upper and lower plates in a caudocranial direction in a scissor jack-like fashion. The implant is deployed through a working cannula, which itself is inserted percutaneously through the pedicle of the vertebra. The working cannula may be about 10 gauge, 6 gauge, or even 4 gauge, and the implant is correspondingly sized smaller than the inner diameter of the working cannula. Thus, the surfaces of the upper and lower tissue support skis may be arched to impart a cylindrical profile to the implant in the collapsed or inserted configuration as it is deployed through the working cannula. In an implant capable of providing an expansion force of up to 1,000 Newtons, it is desirable to limit pressure on the vertebral endplates from the arched surfaces during expansion to the deployed configuration.

[0005] Several known devices can secure intravertebral implants to the pedicles. Exemplary systems for doing so are described in U.S. Patent No. 8,784,491, issued July 22, 2014, and commonly owned U.S. Patent No. 10,603,080, issued March 31, 2020, the entire contents of each of which are incorporated herein by reference. Those systems include a pedicle anchor that includes an external thread configured to be threadably secured to the pedicle with the implant operably coupled to the pedicle anchor. However, while the working cannula is tubular, the pedicle itself is more closely oval or elliptical in shape. Thus, portions of the pedicle are underutilized and the maximum allowable implant for a given anatomy is constrained by the cylindrical profile of the external thread of the pedicle anchor. Summary of the Invention

[0006] Thus, there is a continuing need in the art for intervertebral implants that are secured to the pedicles in a manner that improves the treatment of compression fractures and their sequelae, optionally without the use of bone cement.

[0007] A device for augmenting a vertebral body of a vertebra. The device is configured to include an expandable implant configured to be anchored in a pedicle and deployed within the vertebral body. Anchoring the device in the pedicle can eliminate the need for bone cement and simplify the design of the expandable implant. The device includes an expandable implant and a pedicle anchor coupled to the expandable implant to support the expandable implant in a desired position. The tissue support skis move upon deployment of the expandable implant from an insertion configuration to a deployed configuration to compress adjacent cancellous bone and move the upper endplate of the vertebral body to an elevated or restored height. An actuator can be configured to extend through the expandable implant and deploy the expandable implant from the insertion configuration to the deployed configuration.

[0008] The expandable implant includes a distal end element, a proximal end element, and a strut. The expandable implant can include a strut hub that is directly connected or fixed to the underside of the tissue support ski or integrally formed therewith. The strut can be directly connected or fixed to the strut hub or integrally formed therewith. One, more than one, or all of the struts can include at least one web of material that is a reduced thickness portion configured to plastically deform when the expandable implant is deployed. The strut can be fixed to the distal end element or the proximal end element so that it is angled toward the tissue support ski in the insertion configuration. This angle ensures that the strut buckles in the appropriate direction to urge the tissue support ski upward and away from the longitudinal axis. The strut can be connected to the underside of the distal end portion or the proximal end portion to provide the clearance necessary to angle the strut. In some embodiments, the expandable implant can include a distal truss secured to a distal end element and a distal strut, and a proximal truss secured to a proximal end element and a proximal strut.

[0009] The tissue contacting surface of the tissue support ski may be recessed from the outer contour. The tissue contacting surface may be offset from the longitudinal axis and define a geometric chord of the cylindrical outer contour of the expandable implant. The tissue contacting surface may be partially or entirely planar. The tissue support ski may be moved by an initial lifting approximately equal to a recess before encountering cancellous bone within the vertebral body. The tissue contacting surface may be textured, such as with ridges, grooves, depressions, protuberances, etc. Surfaces or subcomponents of the device may be formed of a porous material to promote bone ingrowth.

[0010] The pedicle anchor includes an anchor body and at least one anchor element movably coupled to the anchor body. The anchor element is configured to be deployed outwardly beyond the anchor body to engage or penetrate the pedicle. The anchor body may define a bore within which a rod of an actuator may be movably disposed. The rod may include a knuckle, the knuckle being separated by a cavity defined by the rod. The anchor element is shaped such that in the insertion configuration an inner edge surface is disposed within the cavity and an outer surface is disposed within the outer contour of the anchor body. The anchor element may be integrally formed with the anchor body and may include a living hinge formed by a thinned portion of material. The knuckle may be a protrusion extending beyond a nominal outer diameter of the rod. The number of knuckles provided may correspond to the number of anchor elements, or one of the knuckles may be configured to deploy an opposing pair of anchor elements. Movement of the rod (translation) causes the knuckle to engage the inner surface of the anchor element, and interference between the knuckle and the anchor element causes the anchor element to pivot or bend outward about the living hinge. The knuckle may include at least one tooth or barb configured to move into irreversible interference engagement with a complementary feature of the anchor element. The anchor element is centered or radially offset from a longitudinal center plane that separates the device into left and right halves. The tissue support ski and the anchor element can be moved in the same expansion plane. Movement of the rod (translation) causes the tissue support ski to move away from the longitudinal axis, and thus movement of the rod (translation) can simultaneously deploy the expandable implant and the pedicle anchor.

[0011] In some embodiments, the anchor element can include fingers integrally formed with the anchor body. The fingers can be formed by defining slots in the anchor body. The rod of the actuator includes cams extending outwardly from opposing sides of the rod. The cams are configured to move into engagement with an inner surface of the anchor element to move the device from the insertion configuration to the anchored configuration. Interference between the cams and the inner surface of the anchor element causes the fingers to bend or pivot outwardly beyond the outer contour of the anchor body. The fingers can include edges defined by the slots that are sharp enough to penetrate and engage the pedicle. Sequentially deploying the expandable implant and the pedicle anchor can include a first input to the actuator to translate (translate) the rod to move the expandable implant from the insertion configuration to the deployed configuration, and a second input to rotate the rod to move the pedicle anchor from the insertion configuration to the anchored configuration. With the rod in the first axial position, the cam distal end is positioned distal to the most distal of the anchor elements. A first input to the actuator moves (translates) the rod from a first axial position to a second axial position where the cam moves into axial alignment with the most proximal of the anchor elements for a second input that rotates the cam to deploy the anchor elements and move the pedicle anchor into the anchor configuration.

[0012] In some embodiments, the distal and proximal end portions may be oval or elliptical to define an outer contour as an oval prism. The width of the expandable implant is greater than its height to form an oval shape. The tissue contacting surface may be oriented along or parallel to the width, which is greater than the height. The device includes a means for rotating the expandable implant relative to the pedicle anchor. The expandable implant may be rotated approximately 90 degrees relative to the pedicle anchor. The expandable implant may include a proximal engagement feature that operably engages a distal engagement feature of the pedicle anchor to permit rotation in a first rotational direction relative to the pedicle anchor and prevent rotation in a second rotational direction relative to the pedicle anchor. The actuator rod may include a head portion configured to engage a keyway of the expandable implant to provide rotation of the expandable implant. The head portion may be non-circular. The device may include a blocking feature that prevents the expandable implant from further rotating in the first rotational direction to an angle greater than a predetermined angle. The predetermined angle may be about 90 degrees, or more typically within the range of 80 to 100 degrees. The blocking feature may be a protrusion defined in a distal end of the bore of the anchor body. The protrusion is oriented radially to interfere with a head portion of the rod when the rod is at the predetermined angle.

[0013] Advantages of the present invention will be readily appreciated as the same becomes better understood by reference to the following detailed description when considered in conjunction with the accompanying drawings. [Brief description of the drawings]

[0014] [Figure 1] FIG. 2 is a cross-sectional elevation view of a device including an expandable implant deployed within a vertebral body and a pedicle anchor engaged with a pedicle. [Diagram 2] FIG. 2 is a cross-sectional plan view of the device of FIG. 1. [Figure 3A]FIG. 2 is a rear cross-sectional perspective view of the device of FIG. 1 with the anchor elements of the pedicle anchor deployed generally along the largest dimension of the pedicle. [Figure 3B] 1 is a schematic diagram of a device of the present disclosure and a known device superimposed over a diagram of a pedicle. By orienting the anchor element in a caudo-cranial direction, as opposed to an external thread, a larger implant can be used for a given pedicle. [Figure 4] FIG. 2 is a front perspective view of the device of FIG. 1. [Diagram 5] FIG. 6 is a cross-sectional elevation view of the device of FIG. 5 in an insertion configuration. [Figure 6] 6 is a cross-sectional elevational view of the device of FIG. 5 taken along section line 6-6, with the device in a deployed configuration. [Figure 7] FIG. 13 is a front perspective view of another embodiment of the device. [Figure 8] FIG. 8 is an exploded view of the device of FIG. [Figure 9A] 9 is a cross-sectional elevational view of the device of FIG. 7 taken along section line 9-9, with the expandable implant and pedicle anchor in an insertion configuration. [Figure 9B] 8 is a cross-sectional elevation view of the device of FIG 7, with the expandable implant in a deployed configuration and the pedicle anchor in an insertion configuration. [Figure 9C] FIG 8 is a cross-sectional elevational view of the device of FIG 7, with the expandable implant and pedicle anchor in a deployed configuration. [Figure 10] FIG. 13 is an exploded view of another embodiment of the device. [Figure 11] FIG. 11 is an elevational view of the device of FIG. 10 with the expandable implant rotated relative to the pedicle anchor after insertion of the disposable implant. [Figure 12A] FIG. 12 is an elevational view of an expandable implant of the device of FIG. [Figure 12B] 12 is an elevational view of another expandable implant of the device of FIG. 11. [Figure 13] FIG. 12B is a top perspective view of the expandable implant of FIG. 12A. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0015] 1-3 are diagrams of device 20 deployed within a vertebra (V), including a vertebral body (VB) and pedicle (VP). The vertebral body defines an interior region having cancellous bone. Device 20 may be used with a system including an access cannula and an introducer device to which device 20 is configured to be removably coupled. Device 20 is configured to augment the vertebral body to an elevated or restored height to which at least one endplate of the vertebral body is displaced, thereby reducing or eliminating pain and other sequelae associated with osteoporotic degeneration, compression fractures, or other related disorders of the spine. Examples of access cannulas, introducer devices, and other instruments suitable for deploying device 20 are disclosed in commonly owned U.S. Patent No. 8,986,386, issued March 24, 2015, the entire contents of which are incorporated herein by reference. It should be noted that this disclosure may also refer to anatomical directions, i.e., cephalad, toward the patient's head or superiorly; caudal, toward the patient's feet or inferiorly; distal, toward the end of the device that is first inserted into the patient (or away from the practitioner); and proximal, toward the practitioner, in accordance with standard medical practice.

[0016] As best shown in FIG. 1, the device 20 includes an expandable implant 22 configured to be deployed in a cephalad direction within a vertebral body to move an upper endplate (UE) away from a lower endplate (LE). The device 20 includes a pedicle anchor 24 coupled to the expandable implant 22 and configured to engage a pedicle to anchor the device 20. The pedicle anchor 24 supports the expandable implant 22 in a desired position, eliminating the need for bone cement. In other words, the system including the device 20 is a cementless system, thereby eliminating the cumbersome steps of bone cement preparation and administration. A cementless system may also be particularly advantageous to reduce the likelihood of long-term post-operative complications in young, active individuals with lifestyles that are prone to dynamic loading of the spine.

[0017] The expandable implant 22 includes tissue support skis 26. The tissue support skis 26 are configured to move from an insertion configuration to a deployed configuration, as described below, upon deployment of the expandable implant 22. The tissue support skis 26 compress adjacent cancellous bone and move the upper endplate of the vertebral body to an elevated or restored height. With the pedicle anchors 24 supporting the expandable implant 22 in the desired position, a single tissue support ski 26 can be used to achieve the desired height restoration in a cementless system. Previous devices that are fully deployed within the vertebral body, i.e., without fixation to the pedicle, typically required radially deployed implants or opposing skis along with bone cement. In the described embodiment, the use of a single tissue support ski 26 allows the tissue support skis 26 to be recessed from the outer contour of the expandable implant 22, thereby increasing the load-bearing surface of the tissue support skis 26. The increased load-bearing surface reduces pressure on the upper endplate from the device 20, thereby reducing the potential for surgical and post-operative complications. Alternatively, it is contemplated that the expandable implant 22 may include a lower strut 49 or a second tissue support ski.

[0018] 4-7 , the expandable implant 22 includes a distal end element 28 and a proximal end element 30. The distal end element 28 and the proximal end element 30 can define a longitudinal axis of the device 20. The distal end element 28 can define a distal end of the device 20, and the proximal end element 30 can define a proximal end of the expandable implant 22. A distal strut 34 or support is coupled to the distal end element 28 and the tissue support ski 26, and a proximal strut 36 or support is coupled to the proximal end element 30 and the tissue support ski 26. The expandable implant 22 can include a strut hub 32 that is directly connected or secured to or integrally formed with the underside of the tissue support ski 26. The distal strut 34 and the proximal strut 36 can be directly connected or secured to or integrally formed with the strut hub 32. As best shown in Figure 4, the expandable implant 22 can include several additional struts. A second distal strut 38 can be coupled to the distal end element 28 and the strut hub 32, and a second proximal strut 40 can be coupled to the proximal end element 30 and the strut hub 32. The first distal strut 34 and the second distal strut 38 can be positioned adjacent to and extending along one another between the distal end element 28 and the tissue support ski 26, and the first proximal strut 36 and the second proximal strut 40 can also be positioned adjacent to and extending along one another between the proximal end element 30 and the tissue support ski 26. A mirror image arrangement of struts can be provided on the opposite side of the actuator 50, described below. In some embodiments, a third distal strut 42 and a fourth distal strut 44 are connected to the distal end element 28 and the strut hub 32, and a third proximal strut 46 and a fourth proximal strut 48 are connected to the proximal end element 30 and the strut hub 32.

[0019] The struts 34-48 are sized and shaped to impart a desired movement to the tissue support skis 26 during deployment of the expandable implant 22. An actuator 50 is secured to the distal end element 28 and configured to receive input from an introducer device (via a user) to draw the distal end element 28 toward the proximal end element 30. The struts 34-48 are formed from a sufficiently rigid material such that drawing the distal end element 28 toward the proximal end element 30 causes the struts 34-48 to articulate in a manner that urges the tissue support skis 26 upwardly and away from the longitudinal axis of the device 20. One, more than one, or all of the struts 34-48 can include at least one web of material 52 (several of which are identified throughout the figures) that is a portion of reduced thickness configured to plastically deform when the expandable implant 22 is deployed within a vertebral body. In other words, the thickness of some of the struts 34-48 is greater than the thickness of the web of material 52 such that stresses are localized to impart bending to the web of material 52 as the expandable implant 22 moves from the insertion configuration to the deployed configuration. The effect of bending is the articulation of the distal struts 34, 38, 42, and 44 relative to the distal end element 28 and tissue support skis 26, respectively, and the articulation of the proximal struts 36, 40, 46, 48 relative to the proximal end element 30 and tissue support skis 26, respectively. The expandable implant 22 may be symmetric about a plane transverse to the longitudinal axis, such that the paired distal and proximal struts articulate in a complementary manner to cause the tissue support skis 26 to be parallel to the longitudinal axis of the device 20 in both the insertion and deployment configurations, and potentially during all movement between the insertion and deployment configurations.

[0020] As best seen in FIGS. 12A and 12B, the struts 34-48 can be secured to the distal end element 28 or the proximal end element 30 so that they are angled toward the tissue support ski 26 in the insertion configuration. The first distal strut 34 is shown oriented at an angle α relative to the longitudinal axis (A) of the expandable implant 22. The remaining struts 36-48 can be angled the same or at a different angle. The angle is slight, but sufficient to ensure that the struts 34-48 buckle in the proper direction and bias the tissue support ski 26 upwardly and away from the longitudinal axis. The angle can be 1-10 degrees, more specifically 1-5 degrees. The use of a single tissue support ski 26 can provide the clearance necessary to angle the struts 34-48 in the manner described above. More specifically, the struts 34-48 can be coupled to the underside of the distal end element 28 or the proximal end element 30 to provide angulation of the struts 34-48 in the insertion configuration, which may not otherwise be feasible with an implant having a second tissue support ski that requires its own associated strut. For example, Figures 12A and 12B show the ends of a first distal strut 34 and a first proximal strut 36 coupled to one of the distal end element 28 and the proximal end element 30, respectively, along the longitudinal axis, and the ends of a second distal strut 38 and a second proximal strut 40 coupled to one of the distal end element 28 and the proximal end element 30 on the opposite side of the longitudinal axis from the tissue support ski 26 (i.e., the underside of the distal end element 28 or the underside of the proximal end element 30). It has been found that the tissue support skis 26 should not extend beyond the outer contour of the device 20 in the insertion configuration, and thus the relatively low attachment points of the posts 34-48 provide clearance not only for the upward angling of the posts 34-48 to account for such constraint, but also for the recess (R) of the tissue support skis 26 from the outer contour of the device 20.

[0021] With continued reference to FIG. 12A and further reference to FIG. 13, the tissue support ski 26 can include an upper or tissue contacting surface 54 opposite its lower surface. The distal end element 28 can include at least a cylindrical portion, and the proximal end element 30 can be cylindrical. As a convention, the outer contour of the expandable implant 22 can be a cylinder defined by the cylindrical portion of the distal end element 28 and the cylindrical body of the proximal end element 30, i.e., the dashed line in FIG. 12A represents the upper surface of the outer contour. Alternatively, it is contemplated that the distal end element 28 and the proximal end element 30 can be oval or elliptical, defining the outer contour as an oval prism. FIG. 13 illustrates one such embodiment in which the width (W) of the expandable implant 22 is greater than its height (H), forming an elliptical shape. The tissue contacting surface 54 of the tissue support ski 26 is recessed (R) from the outer contour. For example, the tissue contact surface 54 can be offset from the longitudinal axis to define a geometric chord of the cylindrical outer contour of the expandable implant 22. The technical advantages of having the tissue contact surface 54 recessed from the outer contour are at least fourfold. First, the tissue contact surface 54 can be partially or entirely planar. FIG. 13 shows a tissue contact surface 54 that is entirely planar and rectangular in shape. Second, the tissue contact surface 54 can be relatively large. In other words, a large proportion of the width of the expandable implant 22 can be utilized as the tissue contact surface 54. This is particularly the case for embodiments in which the expandable implant 22 is elliptical in shape. In other words, the tissue contact surface 54 of the expandable implant 22 of FIGS. 10 and 13 is wider than the tissue contact surface 54 of the expandable implant 22 of FIGS. 4 and 7. Because pressure is a force per unit area, the planar, larger tissue contact surface 54 reduces pressure on the upper endplate both during deployment and once in situ of the device 20. The reduced pressure allows a greater force to be applied to the upper endplate, thereby achieving greater height recovery with less risk of compromising the endplate.When placed in situ, the tissue contacting surface 54 can withstand greater static and dynamic forces on the upper endplate without increasing focal pressure, thereby providing a more robust device. Third, the tissue support ski 26 can be moved with an initial lift approximately equal to the recess (R) before encountering cancellous bone within the vertebral body. Upon encountering resistance from the cancellous bone, the initial lift provides a greater mechanical advantage from the insert. Furthermore, the subsequent encounter with cancellous bone can be perceived as tactile feedback by the surgeon, thus allowing the surgeon to distinguish between internal resistance from the expandable implant 22 itself and resistance from the cancellous bone. Fourth, the tissue contacting surface 54 can be textured to improve engagement with the upper endplate and promote bone ingrowth. For example, the tissue contacting surface 54 can include ridges, grooves, depressions, protuberances, etc., generally designated 55 in FIG. 12B. Additionally or alternatively, tissue contacting surface 54, and / or any portion of the surface of device 20, may be formed from a porous material to promote bone ingrowth.

[0022] It should be understood that any and all of the aforementioned features of the expandable implant 22 described with reference to Figure 12A are or may be included in other embodiments of the expandable implant 22 described herein. The embodiment of the expandable implant 22 of Figure 12A may further include a distal truss 56 secured to the distal end element 28 and the distal struts 34, and a proximal truss 58 secured to the proximal end element 30 and the proximal struts 36. Due to the aforementioned lower connection points between the struts 34-48 along the distal end element 28 and the proximal end element 30, the distal truss 56 and the proximal truss 58 are configured to prevent the distal end element 28 and the proximal end element 30 from flaring outward during deployment of the expandable implant 22. In other words, as the distal end element 28 is drawn toward the proximal end element 30 against resistance from the cancellous bone and against internal resistance of the expandable implant 22 itself, the forces on the lower portions of the distal end element 28 and the proximal end element 30 (e.g., from the struts 34-48) can cause the upper portions of the distal end element 28 and the proximal end element 30 to flare outward in an undesirable manner. The distal truss 56 and the proximal truss 58 distribute the forces in a manner that maintains parallel alignment between the distal end element 28 and the proximal end element 30. The embodiment of the expandable implant 22 of FIG. 12B can further include a lower strut 49. The lower strut 49 can include opposite ends coupled to the distal end element 28 and the proximal end element 30, respectively. The lower strut 49 can include a web of material 52 that is sized and shaped to impart movement of the lower strut 49 away from the longitudinal axis in a direction opposite the tissue support ski 26. The lower strut 49 may provide additional stability of the expandable implant 22 in situ without the need for the clearance required to accommodate a second tissue support ski and its associated strut.

[0023] As discussed above, the device 20 includes a pedicle anchor 24 configured to be anchored within a vertebral pedicle. Returning to FIGS. 1-6, the pedicle anchor 24 includes an anchor body 60 and at least one anchor element 62 movably coupled to the anchor body 60. Although multiple anchor elements 62 are described below, a single anchor element may also be provided. The anchor element 62 is configured to be deployed outwardly beyond the anchor body 60 to engage the pedicle, as shown in FIGS. 1-3A. The anchor element 62 may include a point, edge, corner, or the like that is shaped sufficiently to penetrate the cortical bone of the pedicle. For example, the anchor element 62 may include a trailing edge 64 configured to engage the cortical bone to prevent movement of the device 20 relative to the vertebrae, and in particular to prevent "pull-out" of the device 20 once anchored.

[0024] 5 shows the device 20 in an insertion configuration in which the tissue support skis 26 and anchor elements 62 are positioned within the outer contour of the device 20. FIG. 6 shows the device 20 in a deployed configuration in which the tissue support skis 26 have been moved upward and in an anchored configuration in which the anchor elements 62 have been moved outward beyond the anchor body 60. To move the device 20 between the insertion and deployed configurations, an input is provided to an actuator 50. The actuator 50, which may include a rod 66 removably coupled to an introducer device (not shown), may move (translate) the distal end element 28 to draw it toward the proximal end element 30. The proximal end element 30 may be coupled to or abut a distal end of the anchor body 60, such that the anchor body 60 resists movement of the proximal end element 30 in a corresponding manner. Compressive forces from the distal end elements 28 and the proximal end elements 30 are transferred to the struts 34-48 and the localized stress causes the material webs 52 to buckle, articulating the struts 34-48 and moving the tissue support skis 26 away from the longitudinal axis.

[0025] The anchor body 60 can define a bore 68 within which a rod 66 can be movably disposed. The rod 66 can include a knuckle 70, which can be separated by a cavity 72 defined by the rod 66. The anchor element 62 is shaped such that in the inserted configuration, an inner edge or inner surface 74 is disposed within the cavity 72 and an outer surface, including the trailing edge 64, is within the outer contour of the anchor body 60. The anchor element 62 can be movably coupled to the anchor body 60 in any one of several suitable arrangements. For example, the anchor element 62 can be integrally formed with the anchor body 60 and can include a living hinge 76 formed by a thinned portion of material. In another example, the anchor element can be coupled to the anchor body 60 with a pivot pin or the like. The knuckle 70 can be a protrusion that extends beyond the nominal outer diameter of the rod 66. The number of knuckles 70 provided may correspond to the number of anchor elements 62, or one of the knuckles 70 may be configured to deploy an opposing pair of anchor elements 62. Figures 5 and 6 show four anchor elements 62 (two movably disposed on the upper aspect of the anchor body 60 and two movably disposed on the lower aspect of the anchor body 60) and two knuckles 70, although more or less of either may be provided.

[0026] To move the device 20 between the insertion configuration and the anchor configuration, an input is provided to the actuator 50 to move (translate) the rod 66. In this embodiment, this input may be the same input that deploys the expandable implant 22, so that the expandable implant 22 and the anchor element 62 can be deployed at least approximately simultaneously. The movement (translation) of the rod 66 causes the knuckle 70 to engage an inner surface 74 of the anchor element 62, and interference between the knuckle 70 and the anchor element 62 causes the anchor element 62 to pivot or bend outwardly about a living hinge 76, thereby causing the trailing edge 64 to penetrate the pedicle. The knuckle 70 may include at least one tooth or barb 78 configured to move into irreversible interference engagement with a complementary feature of the anchor element 62. In particular, in the anchor configuration, the barb 78 interference engages an edge of the inner surface 74 of the anchor element 62. As a result, the rod 66 cannot move (translate) distally relative to the anchor body 60, which would otherwise allow the anchor element 62 to pivot or bend inwardly and compromise the fixation effect. It should be understood that the knuckle 70 may be optional, depending on the design of the cavity 72 for the anchor element 62. In other words, if the cavity 72 is deep and large enough to receive the anchor element 62, the outer surface of the rod 66 itself may provide the desired effect for deploying the anchor element 62.

[0027] As mentioned above, the anchor elements 62 can be positioned on the upper and lower aspects of the anchor body 60. This arrangement provides technical advantages over conventional devices that use male threads to engage the pedicle. FIG. 3A shows a cross-sectional perspective view of a pedicle, and it is easy to see that the pedicle is non-circular. In particular, the pedicle is closest to an oval or ellipse in shape, which is represented diagrammatically as pedicle (VP) in FIG. 3B. The schematic on the right side of FIG. 3B is a representative known device (KD) with an outer contour (OP) and male threads (ET), and the schematic on the left side is device 20 with an outer contour and anchor elements (AE). For a given pedicle, the known device cannot accommodate the same size outer contour as the device 20 of the present disclosure, because the male threads penetrate the outer surface of the pedicle. As a result, known devices including expandable portions must be made smaller to fit the pedicle, and the smaller expandable portions of the known devices may not be sufficient to expand the vertebral body to the desired restored height. In contrast, the anchor elements of device 20 provide a greater outer profile without encroaching on the outer surface of the pedicle. Simply put, device 20 advantageously takes advantage of more of the available anatomy of the pedicle to provide a larger working cannula and therefore a larger expandable implant option.

[0028] The illustrated embodiment of the device 20 includes anchor elements 62 disposed about a central longitudinal plane that separates the device 20 into left and right halves. In such an arrangement, the tissue support skis 26 and the anchor elements 62 are configured to move in the same plane of expansion. For example, the tissue support skis 26 can be deployed cranially and the anchor elements 62 can be deployed caudally. However, it should be understood that changes in the radial orientation of one or more of the anchor elements 62 are contemplated. Although the anchor elements 62 may typically be disposed on the upper and lower surfaces of the anchor body 60, the anchor elements 62 may be radially offset from the central longitudinal plane. Based on the pedicle anatomy, whether an individual patient or anthropomorphic data study, it may be desirable to move one or more of the anchor elements 62 3 degrees, 5 degrees, 10 degrees, or 15 degrees or more from the central longitudinal plane. In one example, after analyzing the anatomy of an individual patient's pedicle with a computed tomography scan that can determine specific dimensions, the surgeon can select one of the devices 20 from a catalog of many devices 20, each with a different arrangement of anchor elements 62. The one selected can be optimal along the largest dimension of the pedicle. In alternative embodiments, the anchor elements 62 can be in a triangular, cross, star, pentagonal, hexagonal, or another geometric arrangement. Alternatively, a portion of the anchor elements 62 can be configured to be frangible and separate from the anchor body 60 during deployment. Such an example can include three-dimensional printing of the anchor body 60 with a frangible section. Further alternatives include threads and / or other geometries formed on the outer surface of the anchor elements 62 to facilitate removal of the device 20 when indicated.

[0029] 7-9C, another embodiment of the device 20 is shown in which the anchor elements 62 and their deployment mechanisms are different from those previously described. The expandable implant 22 may be similar or identical to those previously described and is incorporated herein by reference. The anchor elements 62 may include fingers 80 integrally formed with the anchor body 60. The fingers 80 are movably coupled to the anchor body 60. The fingers 80 may be formed by defining a slot 82 in the anchor body 60. The illustrated embodiment shows that the slot 82 is U-shaped, defining three sides of the fingers 80 and providing a living hinge or web of material as the fourth side. Additionally, the illustrated embodiment shows that four of the fingers 80 are disposed on the upper aspect of the anchor body 60 and four of the fingers 80 are disposed on the lower aspect of the anchor body 60. More or fewer fingers 80 may be provided, and the fingers 80 may be disposed on the longitudinal center plane or may be radially offset from the longitudinal center plane, as previously described.

[0030] 8 and 9A-9C show the rod 66 of the actuator 50 including a cam 84. In particular, a portion of the rod 66 can include cams 84 extending outwardly from opposing sides of the rod 66 (one shown). The cams 84 are configured to move into engagement with the inner surface 74 of the anchor element 62 to move the device from the insertion configuration to the anchor configuration. As best shown in FIGS. 9A and 9C, when the rod 66 is in a first rotational orientation, the cams 84 are oriented laterally (sideways) and the nominal outer diameter of the rod 66 is less than the inner diameter defined by the inner surface 74. The rod 66 is configured to move from the first rotational orientation to a second rotational orientation in which the cams 84 are oriented upward and downward. Interference between the cams 84 and the inner surface 74 of the anchor element 62 causes the fingers 80 to bend or pivot outwardly past the outer contour of the anchor body 60. The fingers 80 may include edges defined by slots 82 that are sharp enough to penetrate and engage the pedicle.

[0031] This embodiment of the device 20 allows for sequential deployment of the expandable implant 22 and the pedicle anchor 24. The actuator 50 can be provided with two separate inputs, a first input for moving (translating) the rod 66 to move the expandable implant 22 from the insertion configuration to the deployed configuration, and a second input for rotating the rod 66 to move the pedicle anchor 24 from the insertion configuration to the anchor configuration. Sequential deployment advantageously allows for confirmation of the positioning of the expandable implant 22 in the deployed configuration before (or after) securing the device to the pedicle. In other words, the surgeon can deploy the expandable implant 22 within the vertebral body, visualize the expandable implant 22 under fluoroscopy, make any desired adjustments to the axial position or rotational orientation of the expandable implant 22, and then secure the device 20 in the desired position.

[0032] The cam 84 includes a cam distal end 86 and a cam proximal end 88. The cam distal end 86 and the cam proximal end 88 can define a length of the cam 84, which can correspond to the distance between the most distal of the anchor elements 62 and the most proximal of the anchor elements 62. The corresponding length provides a single input (i.e., a second input) for simultaneously deploying the anchor elements 62. Alternatively, the cam 84 may be dimensioned or contoured to provide for incremental deployment of fewer than all of the anchor elements 62. Starting in FIG. 9A, each of the expandable implant 22 and pedicle anchor 24 is in an insertion configuration. The rod 66 is in a first axial position in which the cam distal end 86 is positioned distally relative to the most distal of the anchor elements 62. A first input to the actuator 50 moves (translates) the rod 66 from a first axial position to a second axial position where the tissue support ski 26 moves away from the longitudinal axis in the manner previously described. The expandable implant 22 is in the deployed configuration and the pedicle anchor 24 remains in the insertion configuration. Movement (translation) of the rod 66 to the second axial position not only deploys the expandable implant 22 but also moves the cam 84 into axial alignment with the most proximal of the anchor elements 62, as shown in FIG. 9B. Once the positioning of the expandable implant 22 is confirmed, a second input rotates the rod 66 to rotate the cam 84, deploying the anchor elements 62 and moving the pedicle anchor 24 to the anchored configuration. This embodiment may also include a locking mechanism to render the deployment of the device 20 irreversible.

[0033] 10-13, another embodiment of the device 20 is shown in which, as previously described, the outer contour of the device 20 may be oval or elliptical. If an elliptical bore is established through the pedicle, the device 20 of the present disclosure may be introduced through the elliptical bore. In particular, the elliptical shape of the anchor body 60 prevents relative rotation between the anchor body 60 and the elliptical bore in the pedicle. This may reduce or eliminate the need for an anchor element 62, as shown in FIG. 10, although the anchor element 62 or a variation thereof may be included to prevent axial movement of the device 20 relative to the vertebrae.

[0034] As mentioned above, the elliptical shape of the expandable implant 22 provides a large tissue contact surface 54. The tissue contact surface 54 is oriented along or parallel to a width that is greater than its height, as shown in FIG. 13. This arrangement results in the tissue support skis 26 being oriented laterally (sideways) after the expandable implant 22 is inserted through the elliptical bore and into the vertebral body. However, as previously mentioned, the tissue support skis 26 are preferably moved upward to cephalad urge the upper endplate of the vertebral body to the desired restored height. Thus, this embodiment provides a means to rotate the expandable implant 22 relative to the pedicle anchor 24, which remains constrained from rotating within the elliptical bore. In one example, the expandable implant 22 can be rotated approximately 90 degrees relative to the pedicle anchor 24.

[0035] The expandable implant 22 can include a proximal engagement feature 90 configured to operably couple with a distal engagement feature 92 of the pedicle anchor 24. More specifically, teeth can be formed on a proximal surface of the proximal end element 30 and complementary teeth can be formed on a distal surface of the anchor body 60. The teeth can be eccentric in one direction to provide a ratchet-like effect. In other words, the expandable implant 22 can be configured to permit rotation relative to the pedicle anchor 24 in a first rotational direction and prevent rotation relative to the pedicle anchor 24 in a second rotational direction opposite the first rotational direction.

[0036] To facilitate rotation of the expandable implant 22 relative to the pedicle anchor 24, the rod 66 of the actuator 50 can include a head portion 94. The head portion 94 is non-circular in cross-section. The expandable implant 22, and more specifically the proximal end element 30, defines a keyway 96 that is non-circular in cross-section in a generally complementary manner to the head portion 94 of the rod 66. For example, FIG. 10 shows that the head portion 94 is rectangular and at least a portion of the keyway 96 is rectangular. Engagement of the non-circular elements prevents relative rotation, and thus an input to the actuator 50 to rotate the rod 66 in a first rotational direction causes a corresponding rotation of the expandable implant 22. The expandable implant 22 can be introduced into the vertebral body in the orientation shown in FIG. 10, after which rotation of the expandable implant 22 relative to the pedicle anchor 24 results in the orientation shown in FIG. 11. The oval shape of the anchor body 60 remains pointing upwards and downwards, but the tissue support skis 26 of the expandable implant 22 now also face cephalad, as desired.

[0037] In the configuration shown in FIG. 11, relative rotation of the expandable implant 22 in the second rotational direction relative to the pedicle anchor 24 is prevented by engagement of the distal engagement feature 90 with the proximal engagement feature 92. However, further rotation of the expandable implant 22 in the first rotational direction relative to the pedicle anchor 24 is not completely prevented. The desired amount of rotation required to cephaladize the expandable implant 22 is often known based on the device design, and the device 20 can include a blocking feature 98 configured to prevent further rotation of the expandable implant in the first rotational direction to an angle greater than a predetermined angle. The predetermined angle can be approximately 90 degrees, or more typically within a range of 80 degrees to 100 degrees. The blocking feature 98 can be a protrusion defined at the distal end of the bore 68 of the anchor body 60. The protrusion is radially oriented to interfere with the head portion 94 of the rod 66 when the rod 66 is at the predetermined angle. In a sense, the head portion 94 of the rod 66 is a complementary blocking feature. The blocking feature 98 allows relative rotation of the expandable implant 22 with respect to the pedicle anchor 24 in both directions within a predetermined range. However, the distal and proximal engagement features 90, 92 prevent relative rotation in a second rotational direction, and thus, in cooperation with the blocking feature 98, effectively lock the expandable implant 22 in a desired rotational orientation. In other words, once the expandable implant 22 has been rotated, for example, 90 degrees in a first rotational direction with respect to the pedicle anchor 24, further rotation in the first rotational direction is prevented by the blocking feature 98, and rotation in the second rotational direction is prevented by the distal and proximal engagement features 90, 92.

[0038] A system for expanding a vertebra utilizing the device 20 is contemplated. In addition to an access cannula and an introducer device, the system can include a posterior element configured to be coupled to an expandable implant, and optionally a spinal rod configured to be coupled to the posterior element in a spinal fusion procedure. The posterior element and spinal rod can be adapted for a spinal fusion procedure in which the device 20 is deployed to adjacent vertebrae. In one example, the posterior element is secured to the anchor body 60. In some embodiments, the system can include an instrument configured to create an elliptical bore. The system can include a first material removal device configured to create a pilot hole in the pedicle, and a second material removal device configured to expand the pilot hole to an elliptical bore through the pedicle. The first material removal device can be a drill, a reamer, or the like, and the second material removal device can be a bur, an awl, or the like. It is understood that in many embodiments, the system may be cementless and may include a bone cement delivery system configured to deliver bone cement through the pedicle anchor 24 into the vertebral body to interdigitate with the expandable implant 22 and cancellous bone.

[0039] Some inventive methods can be described with reference to the following exemplary clauses.

[0040] Clause 1 - A method for expanding a vertebra using a device including an expandable implant, a pedicle anchor coupled to the expandable implant, and an actuator, comprising the steps of: moving a rod within an anchor body of the pedicle anchor to provide an input to the actuator to move the expandable implant from an insertion configuration in which the tissue support skis are located within an outer contour of the device to a deployed configuration, wherein in the deployed configuration, (i) the distal end element moves toward the proximal end element such that the distal and proximal struts move the tissue support skis away from the longitudinal axis of the device, and (ii) at least one anchor element moves relative to the anchor body to extend beyond the anchor body and engage the pedicle of the vertebra.

[0041] Clause 2 - The method of clause 1, wherein the input is a single input for simultaneously deploying an expandable implant and a pedicle anchor.

[0042] Clause 3 - The method of clause 1, wherein the inputs are a first input and a second input, the method including the steps of providing a first input to the actuator to move (translate) the rod within the anchor body to move the expandable implant from an insertion configuration to a deployed configuration and axially align a cam on the rod with at least one anchor element, and providing a second input to the actuator to rotate the rod within the anchor body to create interference between the cam and the at least one anchor element.

[0043] Clause 4 - The method of clause 3, further comprising the step of verifying the position of the expandable implant after the step of providing the first input and before the step of providing the second input.

[0044] Clause 5 - A method of expanding a vertebra using a device including an expandable implant, a pedicle anchor coupled to the expandable implant, and an actuator, wherein the expandable implant and the pedicle anchor are elliptical in shape, the method comprising the steps of: directing the expandable implant into a vertebral body through an elliptical bore in the pedicle; providing a first input to the actuator to rotate the expandable implant relative to the pedicle anchor; and providing a second input to the actuator to move a rod within an anchor body of the pedicle anchor to deploy the expandable implant within the vertebral body.

[0045] Clause 6 - The method of clause 5, wherein the step of providing the first input further includes rotating a head portion of the rod in a first rotational direction, wherein the head portion is rotationally constrained within the expandable implant.

[0046] Clause 7 - The method of clause 6, wherein the step of providing the first input further includes rotating the head portion until a blocking feature of the expandable implant prevents further rotation of the rod in a first rotational direction.

[0047] Clause 8 - The method of clause 7, further comprising the step of verifying that relative rotation of the expandable implant with respect to the pedicle anchor is prevented by attempting to rotate the rod in a second rotational direction opposite to the first rotational direction, wherein complementary engagement features of the expandable implant and the pedicle anchor prevent rotation in the second rotational direction.

[0048] Clause 9 - The method of any one of clauses 5 to 8, further comprising the steps of creating a pilot hole in the pedicle using a first material removal device and expanding the pilot hole into an elliptical bore using a second material removal device.

[0049] Clause 10 - The method of any one of clauses 1 to 9, further comprising the steps of connecting a posterior element to the pedicle anchor and connecting a spinal rod to the posterior element.

[0050] The foregoing disclosure is not intended to be exhaustive or to limit the invention to any particular form. The terminology used is intended to be in the nature of description rather than of limitation. Many modifications and variations are possible in light of the above teachings, and the invention may be practiced otherwise than as specifically described.

Claims

1. 1. A device for expanding a vertebra, including a vertebral body and a pedicle, comprising: an expandable implant comprising: distal and proximal end elements defining a longitudinal axis; a tissue support ski; a distal strut coupled to the distal end element and the tissue support ski; and a proximal strut coupled to the proximal end element and the tissue support ski, the expandable implant configured to be deployed within the vertebral body by moving the distal end element toward the proximal end element such that the distal and proximal struts move the tissue support ski away from the longitudinal axis; a pedicle anchor coupled to the expandable implant, the pedicle anchor comprising an anchor body and at least one anchor element movably coupled to the anchor body; an actuator movable within the anchor body of the pedicle anchor and the expandable implant, the actuator configured to be actuated by a user to deploy the at least one anchor element into engagement with the pedicle; A device comprising:

2. 2. The device of claim 1, wherein the actuator is fixed to the distal end element, the anchor body is coupled to the proximal end element, and the actuator is configured to pull the distal end element toward the proximal end element against resistance from the proximal end element by the pedicle anchor.

3. The device of claim 1 , wherein the anchor body defines a bore and the actuator is a rod extending through the bore.

4. 1. A device for expanding a vertebra, including a vertebral body and a pedicle, comprising: an expandable implant comprising: distal and proximal end elements defining a longitudinal axis; a tissue support ski; a distal strut coupled to the distal end element and the tissue support ski; and a proximal strut coupled to the proximal end element and the tissue support ski; a pedicle anchor comprising an anchor body defining a bore and at least one anchor element movably coupled to the anchor body; an actuator comprising a rod extending through the bore and secured to the distal end element of the expandable implant, the actuator configured to be actuated by a user to move the at least one anchor element relative to the anchor body to engage the pedicle and further to move the distal end element toward the proximal end element, causing the distal and proximal struts to move the tissue support skis away from the longitudinal axis, thereby deploying the expandable implant within the vertebral body; A device comprising:

5. 5. The device of claim 3 or 4, wherein the rod comprises a knuckle configured to move into engagement with an inner surface of the at least one anchor element upon proximal movement of the rod relative to the anchor body.

6. The device of claim 5 , wherein the knuckle comprises a barb configured to move into irreversible interference engagement with a complementary feature of the at least one anchor element.

7. The device of claim 1 or 4, wherein the tissue support ski and each of the at least one anchor element are configured to move in the same plane of extension.

8. The device of claim 1 or 4, wherein deployment of the expandable implant is configured to be simultaneous with deployment of the pedicle anchor.

9. 1. A device for expanding a vertebra, including a vertebral body and a pedicle, comprising: an expandable implant comprising: distal and proximal end elements defining a longitudinal axis; a tissue support ski; a distal strut coupled to the distal end element and the tissue support ski; and a proximal strut coupled to the proximal end element and the tissue support ski, the expandable implant configured to be deployed within the vertebral body by moving the distal end element toward the proximal end element such that the distal and proximal struts move the tissue support ski away from the longitudinal axis; a pedicle anchor coupled to the expandable implant, the pedicle anchor comprising an anchor body and at least one anchor element movably coupled to the anchor body, the pedicle anchor configured to be deployed into engagement with the pedicle; an actuator coupled to the expandable implant and the pedicle anchor, the actuator configured to be actuated by a user to do one of: (i) deploy the expandable implant without deploying the pedicle anchor; and (ii) deploy the pedicle anchor without deploying the expandable implant; A device comprising:

10. 10. The device of claim 9, wherein the actuator is a rod, the rod comprising a cam configured to rotate into engagement with an inner surface of the anchor element upon rotation of the rod relative to the anchor body.

11. The device of claim 10 , wherein the rod is configured to move within the anchor body to an axial position where the cam is aligned with the at least one anchor element.

12. The device of claim 11 , wherein movement of the rod is configured to deploy the expandable implant.

13. 10. The device of any one of claims 1, 4 and 9, wherein the anchor elements comprise spikes or fingers extending from a web of material integrally formed with the anchor body.

14. 1. A device for expanding a vertebra, including a vertebral body and a pedicle, comprising: an expandable implant configured to be deployed within the vertebral body; a pedicle anchor comprising: an anchor body fixedly coupled to the expandable implant and defining a bore; and an anchor element extending from a web of material integrally formed with the anchor body; an actuator coupled to the expandable implant, the actuator comprising a rod extending through the bore of the anchor body, the actuator configured to be actuated by a user to move the rod into engagement with the anchor element, thereby plastically deforming the web of material with the anchor element engaged with the pedicle; A device comprising:

15. 15. The device of claim 1, further comprising a strut hub coupled to the tissue support ski, the distal strut extending between the distal end element and the strut hub, and the proximal strut extending between the proximal end element and the strut hub.

16. a second distal strut secured to the distal end element and the strut hub; a second proximal strut secured to the proximal end element and the strut hub; and 16. The device of claim 15, further comprising:

17. 15. The device of claim 1, further comprising a lower strut secured to the distal end element and the proximal end element.

18. a distal truss secured to the distal end element and to an upper surface of the distal strut; a proximal truss secured to the proximal end element and to an upper surface of the proximal strut; 15. The expandable implant of any one of claims 1, 4, 9 and 14, further comprising:

19. 10. The device of any one of claims 1, 4 and 9, wherein each of the distal end element and the proximal end element is elliptical so as to define an outer contour of the expandable implant that is an elliptical cylinder, and wherein each of the expandable implant and the pedicle anchor includes an engagement feature, and the actuator is further configured to rotate the expandable implant in a first direction relative to the pedicle anchor, and the engagement feature is configured to prevent rotation of the expandable implant relative to the pedicle anchor in a second direction opposite the first direction.

20. 20. The device of claim 19, wherein the pedicle anchor further comprises a blocking feature, and the actuator further comprises a complementary blocking feature configured to engage the blocking feature of the pedicle anchor and prevent rotation of the expandable implant in the first direction greater than a predetermined angle.

21. 20. The device of claim 19, wherein the engagement features are complementary unidirectional teeth.

22. 21. The device of claim 20, wherein the actuator comprises a rod, and the complementary blocking feature is a portion of the rod that is non-circular in cross section and configured to interfere with the blocking feature disposed within a bore defined by the pedicle anchor.

Images