Patent Description:
To date, vertebroplasty techniques have been developed in order to address such maladies. However, existing vertebroplasty techniques to effect a vertebral correction, i.e., to restore a vertebra to its original shape, are often either poorly controlled and/or may not provide a structure to ensure that restoration of a bone is preserved over time following surgery.

For example, kyphoplasty involves introduction of an inflatable balloon into the vertebral body followed by the introduction of fluid under pressure into the balloon to force the cortical shell of the vertebra, and in particular the lower and upper vertebral endplates, to correct the shape of the vertebra under the effect of the pressure. Once the osseous cortical shell has been corrected, the balloon is deflated and withdrawn from the vertebra in order to be able to inject cement into the space created by the balloon within the cortical shell, which is intended to impart sufficient mechanical resistance for the correction to last a significant duration in time. Notable disadvantages of kyphoplasty include its onerous procedural steps and the necessity to withdraw the balloon from the patient's body. Furthermore, the expansion of a balloon is poorly controlled because the balloon's volume is multi-directional, which often causes a large pressure to be placed on the cortical shell in less desirable directions. Such large pressures risk bursting of the cortical shell, and in particular, the lateral part of the cortical shell connecting the lower and upper endplates of a vertebra.

In other examples, techniques are employed that utilize implants which are intended to occupy a cavity in a vertebra. Such implants, however, often succumb to collapse within the weeks and months following surgery as they typically do not support a large enough volume within the vertebra. Indeed, the restored height of the vertebra may diminish over time following surgery. Specifically, areas of the bone that are remote from the implant are weak and over time, compress under loading, even with the implant in place. This could occur, for example, in a space below the implant but within the vertebra.

Thus, a need exists for improved implants and related surgical techniques for the repair of collapsed bone structures, particularly improvements to implant structures and obtainable performance from such structures.

A spinal fusion implant comprising a first and second body member having perforated vertebra-engaging surfaces is known from document <CIT>. The members define a cylindrical body with a rounded end in the collapsed condition. An axially extending threaded activating member within the body is rotated by means of an elongate tool to move the members apart by means of linkages. The linkages carry bone engaging elements which are contained within the body in the collapsed condition but which are driven to protrude through apertures in the first vertebra-engaging surfaces as the implant reaches its fully expanded condition. The linkages are such that the degree of expansion at the rounded end exceeds that at the other end, to account for the lordotic curve of the patient's spine. The rate of expansion of the implant per evolution of the activating member reduces as the implant reaches its fully expanded condition.

Document <CIT> discloses an expandable trial including an inferior portion, a superior portion, and a middle expanding portion as well as load cells for monitoring the load on the trial. The trial may also include recesses on its lateral sides to provide spacing to accommodate a disc removal tool so tissue can be cleared monitoring load. In addition, neural foramen spacing can be monitoring to provide information about how much neural release has been achieved as the disc is cleaned and the spine is positioned and repositioned.

Claim <NUM> defines an expandable implant for bone restoration. Preferred embodiments of the invention are set forth in the dependent claims. The implant includes a first end element and a second end element positioned such that a longitudinal axis of the implant passes through a center of the first end element and a center of the second end element. The implant also includes a plate movable in a first direction and a blade movable in a second direction. A first interconnecting element extends between the plate and at least one of the first end element and the second end element while a second interconnecting element extends between the blade and a first one of the first end element and the second end element. The structure of the implant is such that the implant is configured to be expanded from a collapsed position in which a length of the blade is substantially parallel to the longitudinal axis, to an expanded position in which the length of the blade is non-parallel to the longitudinal axis. Moreover, the second connecting element comprises an arm extending between the blade and the second one of the first end element and the second end element.

In one implementation, the plate and the blade are in a single plane in the collapsed position and in the expanded position. In another implementation, when the blade is moved in the second direction, a tip of the blade is configured to move in an arcuate manner, the tip being remote from an attachment point to the second interconnecting element.

In other implementations, the blade includes a base adjacent to the second interconnecting element and a tip remote from the base, wherein the tip is configured to bend when subjected to a predetermined load. In one implementation, the blade includes a (first) tapered portion proximal to the tip of the blade. In another implementation, the blade includes a second tapered portion between the first tapered portion and the base, wherein the second tapered portion is shallower than the first tapered portion. In still another implementation, the blade includes a recess across a width of the blade, the recess being closer to the tip than the base and functioning as a pivot point between portions of the blade on each side of the recess when the tip of the blade is subjected to a load. In other implementation, the blade includes a planar bottom surface, the planar bottom surface becoming wider relative to a width of the blade from the base toward the tip.

In one implementation, the tip of the blade is bulbous. In some implementations, each of the first interconnecting element and the second interconnecting element include arms. In particular, the first interconnecting element includes a first arm extending between the plate and the first end element and a second arm extending between the plate and the second end element. Similarly, the second interconnecting element includes a third arm extending between a base of the blade and the first end element and a fourth arm extending between the base and the second end element. The arm of the second interconnecting element according to claim <NUM> then is constituted by one of the third arm and the fourth arm. In other implementations, when the implant is in the collapsed position, an axis through a length of the third arm is offset from the longitudinal axis a different amount than an axis through a length of the fourth arm, wherein the axis through the length of the third arm and the axis through the length of the fourth arm are parallel. In yet another implementation, the first axis is offset from the second axis by approximately <NUM>. In another implementation, the blade is configured to pivot about a location on one of the third arm and fourth arm when the blade moves in the second direction. In some variants, the third arm and the fourth arm each include a longitudinal axis therethrough and an angle between the longitudinal axis through one of the third arm and the fourth arm and the length of the blade changes as the blade expands in the second direction.

In one implementation, the blade is movable in the second direction such that the tip of the blade is further from the longitudinal axis than the plate. In another implementation, the implant includes a second blade extending directly from one of the first and second end elements that prevents the tip of the first blade from moving toward the longitudinal axis when the implant is expanded. In another implementation, one of the third arm and the fourth arm includes one of a ball and socket for attachment to the other of the ball and socket on the blade. In yet another implementation, the implant includes a frangible material segment connecting one of the third arm and the fourth arm to the blade. In one implementation, the tip of the blade moves away from the longitudinal axis and toward an insertion end of the implant when moving in an arcuate manner during expansion. In another implementation, the tip of the blade moves away from the longitudinal axis and away from an insertion end of the implant when moving in an arcuate manner during expansion.

In another exemplary implementation, an implant with a first end element, a second end element, a plate and a blade is described. The second end element is positioned such that a longitudinal axis of the implant passes through a center of the first end element and a center of the second end element. The plate is attached to both the first end element and the second end element and is oriented such that an axis parallel to the longitudinal axis passes through a length of the plate. The blade includes a base attached to the first end element and the second end element and has a length extending from the base to a tip. The implant is expandable from a collapsed position to an expanded position, the expansion involving the plate and the blade each moving away from the longitudinal axis in different directions. Prior to, during and following expansion, the plate remains substantially parallel to the longitudinal axis. When the implant is in the expanded position, the tip of the blade is further from the longitudinal axis than the plate. Further, a single plane passes through the plate and the blade when the implant is in the collapsed position and when the implant is in the expanded position.

In one exemplary implementation, the tip of the blade moves further from the longitudinal axis than the base of the blade when the implant is expanded from the collapsed position to the expanded position. In another exemplary implementation, a second axis passes through the length of the blade. In the collapsed position, the second axis is parallel to the longitudinal axis. During expansion, the second axis is at an increasing angle relative to the longitudinal axis. In another exemplary implementation, the plate is attached to the first and second end elements via a first attachment point that is equidistant to the first end element and the second end element. Opposite the plate, the blade is attached to the first and second end elements via a second attachment point that is closer to one of the first end element and the second end element. In yet another exemplary implementation, the tip is a free end of the blade free of attachment to another element in the collapsed position, the expanded position, and at positions in between.

In yet another exemplary aspect, a method of repairing a bone is described (not falling under the scope of the claimed invention). Initially, an implant is introduced into a bone. The implant includes a first end element, a second end element, a plate and a blade. A longitudinal axis passes through a center of the first end element and a center of the second element. Each of the plate and the blade are attached to both the first end element and the second end element. Further, the implant is expandable from a collapsed position to an expanded position such that the plate and the blade are expandable in different directions. Once the implant is introduced into the bone, an implant expander tool is actuated to cause the first end element of the implant to become closer to the second end element of the implant as the plate and the blade move from the collapsed position to the expanded position. During the actuation, the plate remains substantially parallel to the longitudinal axis and the blade rotates about a pivot axis adjacent to one of the first end element and the second end element. The blade rotation causes a tip of the blade remote from the pivot axis to move in an arcuate manner away from the longitudinal axis. The movement of the plate and the blade toward the expanded position creates a cavity in the bone through displacement of material within the bone, such as cancellous bone.

In one exemplary implementation, the method includes injecting cement into the cavity, the cement traversing nearly an entire depth of the bone between opposing cortical surfaces. In one example, the cement flows in between a pair of arms connecting one of the first end element and the second end element with the blade as the cement fills the cavity.

In one exemplary implementation, the plate expands a first distance from the longitudinal axis and the tip of the blade expands a second distance from the longitudinal axis. During this expansion, a difference between the second distance and the first distance becomes greater as the implant approaches the expanded position. In another exemplar implementation, the blade includes a portion adjacent to the tip that bends when subject to a predetermined load during expansion of the blade. In yet another exemplary implementation, the actuating step involves rotating the implant expander tool. In one exemplary implementation, the implant undergoes plastic deformation during expansion such that the plate and the blade do not return to the collapsed position. In yet another exemplary implementation, the method includes engaging the implant with a retaining element disposed within openings in the first end element and the second end element of the implant. With this engagement, the retaining element prevents the implant from moving toward the collapsed position. In yet another exemplary implementation, the expanded position is reached when the plate contacts a first cortical bone surface and the tip of the blade contacts a second cortical bone surface.

In one exemplary implementation, a volume of cancellous bone displaced by the blade during rotation of the blade is a function of a length of the blade and a surface area of the blade applying load onto cancellous bone during rotation. In one example, the volume is greater than a second volume of cancellous bone displaced by the plate during expansion of the implant.

Other objects and advantages of the present disclosure will be apparent from the following detailed description of the present preferred implementations, which description should be considered in conjunction with the accompanying drawings in which like reference indicate similar elements and in which:.

Throughout the disclosure, an expandable implant is described for use in restoring a collapsed vertebral body of a human or animal through expansion of the implant structure once disposed within the vertebral body. However, although described with particular reference to application within vertebral bodies of the spine, it is also contemplated that the implant of the implementations herein may be used in other areas of the body. For example, the implant may be employed within the cancellous bone in other bones of the body as a restorative measure when such bones have collapsed.

In one aspect, the present disclosure relates to an expandable implant structure to repair a collapsed bone structure. In one implementation, an expandable implant <NUM> is as shown in <FIG>. When in an implanted and expanded position, implant <NUM> lies within a vertebra <NUM> as shown in <FIG>. Implant <NUM> includes a first end element <NUM>, a second end element <NUM>, a plate <NUM>, a blade <NUM>, and several interconnecting elements in the form of arms <NUM>, <NUM>, 152A-B, 182A-B extending between one of the end elements and the plate or blade.

A shape of implant <NUM> is largely cylindrical in a closed or collapsed position such that a cross section through the implant is at least partially circular, as shown in <FIG> with the shape of each element shown in <FIG>. Implant <NUM> is comprised of biocompatible material, for example titanium or titanium alloy, and may be manufactured from a tubular body using lathe, laser, and/or electro-erosion manufacturing techniques. Alternatively, additive manufacturing techniques or cast manufacturing may be used.

Implant <NUM> includes a first end element <NUM> and a second end element <NUM>, each being hollow and having a cylindrical shape with tapered portions as shown in <FIG>. In other examples, the exact shape of the end elements may vary from that shown. In the implementation shown in <FIG>, a leading, or distal, end of the implant near an anterior side <NUM> of vertebra <NUM> corresponds to the second end element <NUM> while a proximal end closest to a user inserting the implant into a bone near a posterior side <NUM> corresponds to the first end element <NUM>. The end elements <NUM>, <NUM> are intended to be brought towards one another to allow the expansion of the implant, as represented by a comparison of <FIG> with <FIG> and <FIG>, for example. Accordingly, the two end elements <NUM>, <NUM> are connected to each other through interconnecting elements including a first group of upper arms <NUM>, 163A-B and a second group of upper arms <NUM>, 173A-B via a plate <NUM>, and separately through interconnecting elements including a first pair of lower arms 152A-B and a second pair of lower arms 182A-B via a long blade <NUM>. As seen in <FIG>, each of these arms is rectilinear and in parallel with the other arms when implant <NUM> is in the closed, i.e., collapsed configuration. The configuration of the upper and the lower arms is such that space is provided therebetween in the collapsed position so that a retaining element or other actuation structure may fit inside the implant. Notably, a longitudinal axis of each arm 152A-B is offset from a longitudinal axis of each arm 182A-B, the offset denoted by reference numeral <NUM> in <FIG>. In one example, the offset is <NUM> to ensure the long blade rotates away from longitudinal axis <NUM> during expansion of the implant. As referenced herein, longitudinal axis <NUM> is linear. Longitudinal axis <NUM> is also referred to herein as linear longitudinal axis. In other examples, the offset is an amount ranging from <NUM> to <NUM>.

As shown in <FIG>, each of first end element <NUM> and second end element <NUM> includes an opening therethrough, <NUM> and <NUM>, respectively. These openings <NUM>, <NUM> are sized to accommodate the placement of a shaft of a tool therein, e.g., retaining element <NUM>, the shaft being rotatable to control actuation of the implant. Further, an inner surface <NUM>, <NUM> of the respective end elements <NUM>, <NUM> may include ridges, threads or other engagement features to provide for controlled interaction between the tool and the implant. In one example, the first end element <NUM> or second end element <NUM> which is operational as a distal end of the implant may include a cavity with an enclosure on one side instead of a through opening so that the end element is entirely closed on an outward facing surface facing away from the remainder of the implant.

Continuing to refer to the end elements, first end element <NUM> includes a first inward facing surface <NUM> as shown, for example, in <FIG>. First inward facing surface <NUM> is ring shaped with opening <NUM> passing therethrough. Extending from first inward facing surface <NUM> are upper arms 163A-B, upper arm <NUM>, lower arms 152A-B, and short blade <NUM>. Taking plate <NUM> to be on an upper portion of implant <NUM> and long blade <NUM> to be on a lower portion, upper arm <NUM> extends from first inward facing surface <NUM> to plate <NUM> from a location on surface <NUM> above the other arms. Immediately below upper arm <NUM> and also extending from surface <NUM> to plate <NUM> is a pair of upper arms 163A-B, as shown in <FIG>. Upper arm 163A extends from a lateral side of surface <NUM> opposite that of upper arm 163B, as shown in <FIG>. Extending from surface <NUM> below the upper arms to long blade <NUM> is a pair of lower arms 152A-B. In a manner similar to arms 163A-B, lower arm 152A extends from a lateral side of surface <NUM> opposite that of lower arm 152B. A space in between attachment locations of arms 152A and 152B, respectively, accommodates attachment of short blade <NUM> to end element <NUM>. In this manner, short blade <NUM> extends from surface <NUM> in between lower arm 152A and lower arm 152B to a free end tip <NUM>, as shown in <FIG> and <FIG>, for example. Short blade <NUM> includes a top surface in parallel with axis <NUM> and includes a tapering bottom surface <NUM> such that the short blade becomes smaller towards free end tip <NUM>.

Second end element <NUM> includes a second inward facing surface <NUM> with arms <NUM>, 173A-B and 182A-B extending therefrom in the same manner as described above for first end element <NUM>. Thus, each of upper arms <NUM>, 173A-B extend from second inward facing surface <NUM> to plate <NUM> while each of lower arms 182A-B extend from second inward facing surface <NUM> to long blade <NUM>.

Plate <NUM> includes a convex upper surface <NUM> as shown in <FIG>, curved in a direction transverse to axis <NUM>. While implant is in a closed position, as shown in <FIG>, plate <NUM> has a length close to a distance between first and second end elements <NUM>, <NUM>. In other variations, the length of the plate relative to the distance between the first and the second end elements may be greater or lesser than that shown in <FIG>. In a central region of plate <NUM> and extending inward from a body of plate <NUM> toward axis <NUM> is a base portion <NUM>. Base portion has a length extending over a central portion of the plate length between a first end surface <NUM> and a second end surface <NUM>. Arms <NUM>, 163A-B extend from first end surface <NUM> of base portion <NUM> while arms <NUM>, 173A-B extend from second surface <NUM> of base portion <NUM>, as best shown in <FIG> and <FIG>. Base portion <NUM> is one example of an attachment point between plate <NUM> and the upper arms.

As noted above, the upper arms include first group of upper arms <NUM>, 163A-B and second group of upper arms <NUM>, 173A-B. Having described where each arm interfaces with other structures of implant <NUM> at its ends, we turn to the structures of the arms themselves. Upper arms <NUM>, <NUM> each have a width close to a diameter of the first and the second end elements. Upper arms 163A-B and 173A-B are pairs of arms below arms <NUM>, <NUM>, respectively, and are narrower than arms <NUM>, <NUM>. Each of the upper arms (and lower arms) has a thin web of material, also described as a material web, at its opposite ends. This material web undergoes plastic deformation when subject to loading, thereby functioning as an effective pivot point for adjacent elements. Put another way, through plastic deformation of the web material, an arm folds under the plate (or blade) as the first end element and the second end element are brought closer to one another, while the plate translates, or blade rotates, away from the central linear axis <NUM>. Further, the material web is an articulation area formed by the thinning of a wall that is interposed between an end element and the plate or the blade. In one example, the material web is a weakened zone of material. In another example, the material web is formed through fabrication of a groove in the arm. Such a material web provides one example of a material web that is plastically deformable without breaking. In some examples, the material webs control the expansion of the implant by deforming in a predetermined manner to a predetermined extent. Further variations on the material web may be as described in <CIT> (the '<NUM> Patent), <CIT> (the '<NUM> Patent), and <CIT> (the `<NUM> Patent).

On the upper arms, arm <NUM> has webs <NUM>, <NUM>, and arms 163A-B have webs 167A-B, 168A-B. One end of each arm <NUM>, 163A-B abuts first end element <NUM> while the other abuts surface <NUM> of base portion <NUM>. Similarly, upper arms <NUM> and 173A-B opposite the aforementioned arms also include material webs at their ends abutting surface <NUM> of second end element <NUM> at one end and surface <NUM> of base portion <NUM> at an opposite end. In particular, material webs <NUM>, <NUM>, 177A-B and 178A-B correspond to material webs <NUM>, <NUM>, 167A-B and 168A- B, respectively.

Long blade <NUM> includes a base <NUM> attached to the remainder of implant <NUM> and has a length extending from base <NUM> to a free end tip <NUM>, as shown in <FIG>. Tip <NUM> is a free end in that it is free of attachment to another element in the collapsed position, the expanded position, and at positions in between. Long blade <NUM> includes a central portion <NUM> and a tapered portion <NUM>, the tapered portion terminating at free end tip <NUM>. With tapered portion <NUM>, long blade <NUM> has a tip that is sharpened to an extent. The geometry of long blade <NUM>, particularly the tapered portion, improves its ability to bend when subject to loading. A lower surface of long blade, facing away from the remainder of implant <NUM>, is defined by a ridge <NUM> having a peak aligned with a central axis of long blade <NUM> and extending along a length of blade <NUM>, as best shown in <FIG>. The length of blade <NUM> is such that free end tip <NUM> extends directly under short blade <NUM> when implant <NUM> is in a collapsed position, as shown in <FIG>. In particular, tapered portion <NUM> of long blade <NUM> is positioned directly under tapered surface <NUM> of short blade <NUM> when the implant is in the collapsed position such that short blade <NUM> does not prevent long blade <NUM> from being positionable parallel to linear longitudinal axis <NUM>. Nonetheless, free end tip <NUM> of long blade <NUM> is close to first inward facing surface <NUM> when implant <NUM> is in the collapsed position. As noted above, blade <NUM> is connected to the remainder of implant <NUM> via first pair of lower arms 152A-B extending from a first end <NUM> of base <NUM> and second pair of lower arms 182A-B extending from a second end <NUM> of base <NUM>. Base <NUM> is one example of an attachment point between the long blade and the lower arms.

As seen in <FIG>, base <NUM> is positioned closer to second end element <NUM> than first end element <NUM> such that arms 152A-B are much longer than arms 182A-B. The position of base <NUM> on the implant provides room for blade to extend across a significant portion of the implant length so that a longer blade is accommodated. As will be described in greater detail below, the longer blade is advantageous in that it allows for a larger sweeping motion below the implant to remove a greater volume of cancellous bone from the proximal end of the implant toward the distal end of the implant as the blade sweeps downward, as shown in <FIG>, or alternatively, from the distal end to the proximal end, when the implant is structured with a blade oriented in an opposite direction.

Lower arms 152A-B include structure similar to that of the upper arms described above. Each lower arm 152A, 152B has a length extending from first end element <NUM> to long blade <NUM>, a material web 154A-B abutting first end element <NUM> and a material web 156A-B abutting base <NUM> of long blade <NUM>. As shown in <FIG>, a gap exists between arms 152A and 152B. Lower arms 182A-B include a material web adjoining second end <NUM> of base <NUM> to second end element <NUM>. As shown in <FIG> and <FIG>, lower arms 182A-B have a constant thickness over their respective lengths, although it is contemplated that the specific sectional dimensions may vary over the arm length. In one example, the lower arms between base <NUM> and second end element <NUM> include a larger cross-sectional size further from their ends to cause plastic deformation to occur at a desired point on the arm, such as adjacent to the second end element. As shown in <FIG>, expansion of plate <NUM> and long blade <NUM> occur in a single plane. Thus, in the collapsed position shown in <FIG>, in the expanded position shown in <FIG>, and in positions in between, the plate, long blade, and arms of the implant are all in a single, common plane.

In one implementation, implant <NUM> is as shown in <FIG>. In <FIG>, like reference numerals refer to like elements, and unless otherwise indicated, referenced elements may be as described for implant <NUM>, but within the <NUM>-series of numbers. Implant <NUM> includes a first end element <NUM>, a first inward facing surface <NUM>, a second end element <NUM>, a second inward facing surface <NUM>, a plate <NUM>, and a long blade <NUM>. Long blade <NUM> is attached to first end element <NUM> and second end element <NUM> via first pair of lower arms 252A-B and second pair of lower arms 282A-B, respectively. The first pair of lower arms 252A-B extending from a first end <NUM> of base <NUM> and the second pair of lower arms 282A-B extending from a second end <NUM> of base <NUM>. Lower arms 252A-B include material web 254A-B at an end abutting first end element <NUM> while at an opposite end, arm 252A-B forms one part of a ball and socket joint. As shown in <FIG>, each of arms 252A-B provide the ball component while the first end <NUM> of base <NUM> of blade <NUM> provides sockets (not shown) corresponding to the ball components. In this manner, a surface at the first end <NUM> of base <NUM> includes recessed surfaces (not shown) to receive the ends of arms 252A-B. In an alternative configuration, the elements are reversed such that the arms 252A-B have a socket on their end surfaces and base <NUM> has protrusions to define the ball of the ball and socket. The ball and socket is designed so that long blade <NUM> and arms 252A-B pivot about the ball and socket connection, while the connection point rotates away from linear axis <NUM>. This rotational movement mirrors that occurring during expansion of implant <NUM> that includes material web 156A-B, such as is shown in <FIG>. As such, the ball and socket connection provides for the relative movement of elements as described in implementations having a material web connection between the lower arm and the long blade while also preserving the attachment between lower arms 252A-B and long blade <NUM> during expansion. Additionally, in this arrangement arms still undergo one way expansion via plastic deformation of material webs 254A-B and 282A-B, for example. It should be appreciated that functional equivalents of a ball and socket joint may also be used in place of the ball and socket of this implementation.

In one implementation, an implant <NUM> includes lower arms 352A-B attached to long blade <NUM> through a frangible material segment 356A as shown in <FIG>. Frangible material segment 356A provides the only connection between each lower arm 352A-B and long blade <NUM>, and it can be seen in <FIG> that an end face of arms 352A-B is not attached to first end <NUM> of base <NUM>. Frangible material segment 356A provides a support function so that prior to use of the implant, when the implant is closed and in the collapsed position, blade <NUM> is held in position in part through support by the arms 352A-B via frangible material segment 356A, as shown in <FIG>. However, implant <NUM> is structured so that when load is applied to the first end element, i.e., when the first end element of the implant moves closer to the second end element, and the plate and blade are subject to loads causing them to move further apart and expand, movement of arms 352A-B and long blade <NUM> causes tension therebetween such that frangible material segment 356A breaks. In this manner, implant <NUM> is structured so that long blade <NUM> is pivotable about the lower arm located between base <NUM> and the second end element upon breakage of frangible material segment 356A.

In <FIG>, another implementation of the implant is shown where like reference numerals refer to like elements, within the <NUM>-series of numbers. Implant <NUM> includes a first end element <NUM>, a second end element <NUM>, a plate <NUM>, a base <NUM>, a group of upper arms <NUM>, 463A-B, <NUM>, 473A-B, a long blade <NUM>, and a group of lower arms 452A-B, 482A-B. Lower arms 452A-B, 482A-B and blades <NUM>, <NUM>, however, are reversed relative to the end elements of implant <NUM>. In particular, base <NUM> of long blade <NUM> is adjacent to first end <NUM> of implant <NUM>. In this manner, implant <NUM> is configured so that when first end element is moving closer to second end element during expansion of the implant, free end tip <NUM> of long blade <NUM> arcs away from central axis <NUM>. This arcuate motion is downward and away from second end element <NUM> and in a proximal direction toward the user. Thus, when implant <NUM> is inserted into a vertebra, for example, long blade <NUM> is attached so that it expands in an arcuate manner from an anterior side toward a posterior side of the vertebra.

In <FIG>, another implementation of the implant is shown where like reference numerals refer to like elements, within the <NUM>-series of numbers. Implant <NUM> includes a first end element <NUM>, a second end element <NUM>, a plate <NUM>, a base <NUM>, a group of upper arms <NUM>, 563A-B, <NUM>, 573A-B, a long blade <NUM>, and a group of lower arms 552A-B, 582A-B. As shown in <FIG>, each of first end element <NUM> and second end element <NUM> includes an opening therethrough, <NUM> and <NUM>, respectively. These openings <NUM>, <NUM> are sized to accommodate the placement of a shaft of a tool therein, e.g., retaining element <NUM> with ridged portion <NUM>, the shaft being rotatable to control actuation of the implant. Retaining element <NUM> includes egress apertures 505A, 505B, through which cement <NUM> exits retaining element <NUM> and enters the cavity within the bone.

<FIG>, shows that arms 582A-B, effectively material webs, connecting blade <NUM> to first end element <NUM>, are thicker than corresponding material webs <NUM>, 567A-B of the upper arms. Because there is only one arm layer on the lower side of the implant, the material web is thicker to compensate for the single level of support and to provide sufficient capacity to transfer loads. In one example, arms 582A-B are <NUM> thick. Additionally, as shown by reference numeral <NUM> in <FIG>, a longitudinal axis through arms 582A-B is offset from a longitudinal axis through arms 552A-B such that arms 552A-B are further from linear longitudinal axis <NUM>. The arms are offset by an amount to optimize the expansion function of the blade, i.e., to ensure the blade expands outwardly when first end element and second end element move toward one another. In one example, the offset is <NUM>. In other examples, the offset is an amount ranging from <NUM> to <NUM>. Inclusion of arms offset <NUM> from one another on the lower side of the implant is rendered simpler due to the additional space available with only a single layer of arms on the lower side of implant <NUM>, as shown in <FIG>.

On the upper arms, upper arm <NUM> has webs <NUM>, <NUM>, and arms 563A-B have webs 567A-B, 568A-B. One end of each arm <NUM>, 563A-B abuts abutting surface <NUM> of second end element <NUM> while the other abuts surface <NUM> of base portion <NUM>. Similarly, upper arms <NUM> and 573A-B opposite the aforementioned arms also include material webs at their ends abutting first end element <NUM> at one end and surface <NUM> of base portion <NUM> at an opposite end. In particular, material webs <NUM>, <NUM>, 577A-B and 578A-B correspond to material webs <NUM>, <NUM>, 567A-B and 568A- B, respectively.

As shown in <FIG>, blade <NUM> is flat on an upward facing side <NUM> and wider relative to an outer width of the implant compared to long blade <NUM>. In particular, <FIG> illustrates that a width of long blade <NUM> through tapered portions <NUM>, <NUM> is only slightly narrower than base <NUM>, where base <NUM> has a width corresponding to an outer width of implant <NUM>. Blade <NUM> includes a first tapered portion <NUM> extending from base <NUM> and a second tapered portion <NUM> extending from first tapered portion <NUM> to tip <NUM>. Each tapered portion is defined by a planar surface, as shown in <FIG>, becoming wider toward tip <NUM>. Bottom surfaces <NUM> outside the planar tapered portions <NUM>, <NUM> may be slightly curved or rounded, again, shown in <FIG>. The geometry of blade <NUM>, and in particular, its downward facing surface area, shown in <FIG>, for example, is maximized relative to the outer dimensions of the implant. Put another way, a length of the blade is close to a length of the implant while a width of the blade is close to a width of the implant. This geometry maximizes the capacity of the blade to displace material, such as cancellous bone, as the implant is expanded. Tip <NUM> is rounded or bulbous, and extends across the width of long blade <NUM>. In one example, an angle of taper for first tapered portion is two degrees and for second tapered portion is four degrees. In this example, providing a second tapered portion <NUM> to <NUM> in length further optimizes the ability of the long blade to bend when subject to a predetermined load. A second tapered portion <NUM> in length is particularly advantageous. In this and other examples, the sectional radius of rounded tip may be <NUM>. In one example, the long blade is <NUM> in width while the widest location on the planar surface of the second tapered portion adjacent to the tip is <NUM>.

Base <NUM> of long blade <NUM> is adjacent to first end element <NUM> so that free end tip <NUM> of long blade <NUM> arcs away from second end element <NUM> and toward first end, i.e., in a proximal direction. In an alternative configuration, the base may be positioned in a reverse configuration and adjacent to the second end element <NUM> so that tip <NUM> of long blade <NUM> arcs away from linear longitudinal axis <NUM> in an opposite direction from that exhibited by implant <NUM> shown in <FIG>.

As discussed above, one advantage of implant <NUM> when inserted and expanded in a bone structure, such as a vertebra, is that it includes a blade with a large surface area, so that during an expansion process when the blade arcs away from linear longitudinal axis <NUM>, a volume of cancellous bone is displaced that corresponds to the width of the blade, the large relative width of the blade increasing the volume displaced. In turn, the increased displacement of cancellous bone creates a wider cavity below the implant so that a greater amount of cement can be disposed therein to complete a repair using the implant. Additionally, in instances where the blade path causes the tip of the blade to contact a lower plate, the geometry of the blade is such that the blade bends and otherwise deforms when subject to loading, due to contact with a cortical bone surface, for example, thereby reducing the possibility that tip <NUM> of blade will puncture the vertebral body when load continues to be applied to blade after it makes contact with the cortical bone. This advantage is further enhanced because tip <NUM> of blade <NUM> is rounded, as shown in <FIG> and <FIG>, for example, reducing the risk of cortical bone puncture.

In another implementation, the implant of <FIG> includes a blade <NUM> as shown in <FIG>. This blade includes base <NUM>, and a weak section in the form of recess <NUM> across the blade width defining a weak point in the blade structure. In other respects, like reference numerals refer to like elements in implant <NUM>. Blade <NUM> is advantageous in that when blade <NUM> is under load and in contact with a cortical bone, a distal portion <NUM> of blade <NUM> between recess <NUM> and free end <NUM> will bend or break from the remainder of the blade and, irrespective of whether distal portion <NUM> bends or breaks, blade <NUM> will not penetrate the bone. This provides an added measure of protection to ensure no cortical bone is punctured when the implant is inserted into and expanded within a vertebral body. In other examples, a feature similar to recess <NUM> may be employed in a blade of any implant implementation described herein.

In yet another implementation, an implant <NUM> includes two blades: an upper blade <NUM> and a lower blade <NUM>, as shown in <FIG>. Unless otherwise noted, like reference numerals refer to like elements. Below linear longitudinal axis <NUM> is lower blade <NUM> and above linear longitudinal axis <NUM> is upper blade <NUM>. Arms 782A-B connect the lower blade <NUM> to first end element <NUM>, and arms 752A-B connect the lower blade <NUM> to the second end element <NUM>. Likewise, arms 777A-B connect the upper blade <NUM> to first end element <NUM>, and arms 763A-B connect the upper blade <NUM> to the second end element <NUM>. The arms 752A-B, 763A-B, 777A-B, 782A-B may be similar or the same as those in implant <NUM>, for example. Implant <NUM> is symmetrical, and accordingly, features of upper arms and blade <NUM> are the same as those for lower arms and blade <NUM>. <FIG> illustrates implant <NUM> in a collapsed position while <FIG> illustrates implant <NUM> in an expanded position.

The implant structure may be varied in many ways. For example, upper arms connecting an end element with the plate may be arranged so that a single arm connects the first end element to the plate and a single arm connects the second end element to the plate. To accommodate this structure, the web of each arm may have a greater thickness than in other implementations so that each arm can bear greater loads. In other configurations, the arms may be offset to a greater extent relative to a central longitudinal axis of the implant to provide space for a retaining element. An increased offset may be desirable where the arms are of larger cross-sectional size. Similar variations are possible in the lower arms. In another example, an implant includes a plate above a central longitudinal axis and two blades adjacent to one another below the central longitudinal axis. In this configuration, the two blades expand in a matching arcuate movement when the first and second end elements of the implant move toward one another. In other examples, a long blade of the implant may include a hinge in place of a recess so that a free end portion of the blade rotates upon contact with a cortical bone to prevent puncture during expansion of the blade. In yet another example, the tip may include a spring feature to serve a similar function. In other examples, the blades of the various implementations described herein may include rounding features at a tip of the blade to minimize the risk of cortical bone puncture during use. In still further examples, a cross-sectional shape of the plate, short or long blade, arms and end elements may vary from that shown in the depicted implementations. In other examples, the position of the long blade relative to the implant ends may be reversed relative the orientation described for each of the above implementations. Thus, if the long blade moves in an accurate manner from the anterior side of the vertebra toward the posterior side, it may also be structured to rotate from the posterior side to the anterior side.

In another aspect, the present disclosure relates to systems for repairing vertebral bodies. In one implementation, a system includes implant <NUM> and retaining element <NUM> attached thereto via placement of retaining element <NUM> into first and second end elements <NUM>, <NUM> of implant <NUM>, respectively. One example of such a system is shown in <FIG>. Retaining element <NUM> provides a structure upon which end elements <NUM>, <NUM> may be brought closer together through plastic deformation of the arms, e.g., material webs on the arms, while ensuring that implant <NUM> does not collapse after expansion.

In another implementation, a system may include an implant, a retaining element and an implant expander. In such an implementation, the implant expander is placed over the retaining element and contacts the implant during use when actuating the system to expand the implant. In yet another implementation, a system may include an implant, a retaining element, an implant expander and an injector transfer tube. With a fully expanded implant, the injector transfer tube is advanced and positioned within the implant expander. The injector transfer tube is configured so that cement filler may be injected from within the injector transfer tube into the bone structure repaired by the implant.

In another aspect, the implant may be included together with other tools as a kit. In one implementation, a kit includes two implants, and one or more of an implant expander, a trocar, a guidewire, a reamer, a template, a cannula plug and an injector transfer tube. In a variant, a plurality of any one of the aforementioned tools may be included. In a further variant, the kit includes a single implant along with a combination of the aforementioned tools. In yet another variant, the kit includes three or more implants. If the kit includes more than a single implant, the implants within the kit may vary in overall size or materials, from which the most suitable implant may be chosen for a particular surgery. Any combination of implants and tools may also be included in a single package or in separate packages which may be later brought together as a kit.

The kit may be varied in many ways. For example, it is contemplated that any combination of particular implants and tools as described herein may further include other tools or instruments not otherwise described as part of a kit. The various combinations of elements of any contemplated kit may be included in a single package or distributed among multiple packages. In other examples, the kits contemplated herein may be accompanied by an instruction manual on how to perform one or more of the methods of using the contents of the kit.

In another aspect, the present disclosure relates to a method of using (not falling under the scope of the claimed invention) an implant to repair a collapsed bone structure. One implementation of this method is depicted in <FIG> and <FIG>. Initially, implant <NUM> is inserted into a collapsed bone structure such as a vertebral body, for example. This may be accomplished with the use of tools such as an implant expander <NUM> shown in <FIG>. To use the implant expander, the implant is attached to a distal end of the implant expander. In one example, this may be accomplished through threaded engagement between a rod (not shown) extending through a tube of the implant expander and an interior surface within second end element <NUM> of the implant. When the implant is attached, the tube of the implant expander that surrounds the rod abuts first end element <NUM>. The tube is sized to pass over an exposed portion of retainer element <NUM>. When the implant is first inserted, it is in a collapsed position, as shown in <FIG>. In some examples, the steps preceding insertion of the implant for the preparation of a portal into the vertebral body may be as described in the '<NUM>, '<NUM> and '<NUM> Patents. In another example, preparation involves the insertion of a trocar into the bone, followed by placement of a guidewire through the trocar. A portion of the trocar is then removed so that a reamer may be slid over the guidewire. This is followed by drilling into the bone and cleaning the drilled pathway. Other tools may also be used at this juncture, such as a cannula plug to verify the dimensions of the portal for implant placement. In the implementation shown in <FIG>, two portals in vertebra <NUM> are prepared for two implants <NUM>, 100A, respectively. Nonetheless, it is contemplated that a repair may involve the placement of a single implant or multiple implants into the bone, a quantity of implants inserted chosen based on the severity of the deterioration or injury, and/or the size of the bone, for example.

With implant <NUM> in a desired position within the vertebral body, implant expander <NUM>, and 190A if two portals in vertebra <NUM> are prepared for two implants <NUM> and 100A, is actuated by rotating a handle on the implant expander, denoted by <NUM> in <FIG>. Rotation of the handle causes the rod within the implant expander to translate axially toward the handle while simultaneously first end element <NUM> becomes closer to second end element <NUM>. One example of a handle that provides such function includes an internal structure that converts the rotational actuation into a linear translation. During this process, the tube abutting first element <NUM> translates the same amount but in an opposite direction to translation of the second end element. Turning to <FIG>, retaining element <NUM> includes a ridged portion <NUM> so that as first end element <NUM> becomes closer to second end element <NUM>, inner surface <NUM> defining opening <NUM> through first end element <NUM> is incrementally engageable with corresponding ridges <NUM> on retaining element <NUM>. This is one feature that prevents implant <NUM> from returning to the collapsed position after expansion.

When first end element <NUM> moves toward second end element <NUM>, each of the arms of implant <NUM> pivot about the end elements to which the arms are attached. In particular, and as shown in <FIG>, arms <NUM>, 163A-B pivot upward about their respective webs <NUM>, 167A-B, along with a similar pivoting motion in the other upper arms <NUM>, 173A-B. As the arms pivot, plate <NUM> translates upward in a plane through the implant while a length of plate <NUM> measured on bearing surface <NUM> remains parallel to linear longitudinal axis <NUM> (compare <FIG> and <FIG>). It should be appreciated that the orientation of the plate and the linear longitudinal axis may be substantially parallel, and that the plate may be oriented at a slight angle relative to the longitudinal axis due to surgical conditions or tolerances in the manufactured implant. As the plate translates in an upward direction, cancellous, i.e., soft bone within the vertebra is displaced by the plate. On the lower side of the implant, movement of end elements <NUM> and <NUM> toward one another cause arms 152A-B to pivot about material webs 154A-B, 156A-B and arms 182A- B to plastically deform, arms 182A-B functioning as material webs. This, in turn, causes long blade <NUM> to move in an arcuate manner about arms 182A-B, the arcuate movement being in the plane through the implant and in a downward direction. As with the expansion of the plate, arcuate movement of long blade <NUM> causes cancellous bone to be displaced in its path. Because of the length of long blade <NUM> and its path through the cancellous bone as it pivots about arms 182A-B, significantly more cancellous bone is displaced by long blade <NUM> compared with the upper plate <NUM>. This is clear from <FIG>, where a path of the blade on the lower side of the implant extends to a lower plate <NUM> of vertebral body <NUM> while a path of the plate on the upper side extends to the much closer upper plate <NUM> of vertebral body <NUM>. The sharpened shape of long blade <NUM> through tapered portion <NUM> toward tip <NUM>, best shown in <FIG>, promotes cutting through the cancellous bone while the blade is rotated to reduce resistance during the expansion process. As noted above, deformation in the material webs that facilitates the pivoting action of the arms is plastic deformation, and accordingly, the plate and blade will remain in an expanded position following expansion.

During the expansion procedure, long blade <NUM> rotates due to base <NUM> being closer to second end element <NUM> than it is to first end element <NUM> and arms 152A-B being longer than arms 182A-B, as shown in <FIG>. Rotation is also facilitated due to offset <NUM> between arms 152A-B and arms 182A-B. Thus, as the lower arms pivot, base <NUM> rotates counterclockwise, causing tip <NUM> of long blade <NUM> to travel in an arc from its starting position shown in <FIG> toward anterior side <NUM> and bottom plate <NUM> of vertebra <NUM> (shown in a later procedural step in <FIG>). As an added measure to ensure long blade <NUM> travels downward, short blade <NUM> is positioned to prevent long blade <NUM> from rotating toward a central region of the implant. In its starting position, long blade <NUM> is parallel to linear longitudinal axis <NUM>, as shown in part in <FIG>. During expansion, long blade <NUM> becomes angled relative to linear longitudinal axis <NUM> and moves further away from linear longitudinal axis <NUM> as end portions <NUM>, <NUM> are moved toward one another. Because arms 152A-B are positioned on lateral sides of short blade <NUM>, each arm 152A-B pivots past short blade <NUM> without interference.

<FIG> shows implant <NUM> partially expanded. Once implant <NUM> is fully actuated, it is positioned as shown in <FIG>. One advantage of implant <NUM> is that through its expansion, plate <NUM> operates to restore the depth, i.e., height, of the vertebral body above the implant. Another advantage of bone restoration using implant <NUM> is that, when expanded, it creates a path for cement in the bone that traverses nearly the entire depth of the vertebral body through the expansion of plate <NUM> and blade <NUM>. In particular, and as is shown in <FIG>, this is accomplished through the formation of a cavity extending between surface <NUM> of plate <NUM> abutting an interior cortical surface of top plate <NUM> and tip <NUM> of blade <NUM> abutting an interior cortical surface of bottom plate <NUM>. As will be described further below, the creation of a cavity extending between plates <NUM> and <NUM> provides room for cement to be deposited throughout a depth of the vertebral body thereby creating a more durable repair than one where cement only fills a portion of the bone depth. Additionally, in variants where the plate and/or the blade have a width close to that of the implant, compared to variants with plates and/or blades having a narrower width, a volume of cancellous bone displaced is maximized, further increasing the amount of cement that can be disposed in the bone cavity for the repair and improving the distribution of cement in the cavity. Thus, implant <NUM> is used to create a cavity so that sufficient cement is deposited throughout the bone depth to minimize any loss of restored bone height following surgery.

Although long blade <NUM> is shown expanded at a particular angle in <FIG>, the angle for full expansion may be varied as a matter of design choice to suit surgical needs. For example, an angle between linear longitudinal axis <NUM> and long blade <NUM> in the expanded position may be thirty degrees, sixty degrees or eighty degrees. In one example, as the implant is expanded toward the expanded position, the plate expands a first distance from the linear longitudinal axis and the tip of the blade expands a second distance from the linear longitudinal axis in a manner such that a difference between the second distance and the first distance becomes greater as the implant becomes closer to reaching the expanded position. In some examples, a distance from the linear longitudinal axis of the implant to the tip of the blade is nearly three times a distance measured from the linear longitudinal axis to the plate when the implant is fully expanded.

Once implant <NUM> is properly positioned and fully expanded, an injector transfer tube <NUM> is inserted over retaining element <NUM> and cement <NUM>, e.g., bone cement, is injected through the transfer tube and into a space within the vertebra previously cleared of cancellous bone, as described above. Retaining element <NUM> includes egress apertures 105A, 105B, through which cement <NUM> exits retaining element <NUM> and enters the cavity within the bone, as shown in <FIG>. This form of cement injection is also described in at least some implementations of the '<NUM>, '<NUM> and '<NUM> Patents, along with other alternatives and variations. As cement <NUM> is injected into the cavity through the egress apertures 105A, 105B, it flows at least in part through the gap between arms 152A and 152B. Thus, the gap between arms 152A, 152B provides improved flow of cement into the cavity, thereby improving the overall structural repair. Because the cavity formed in the vertebra extends close to respective plates <NUM> and <NUM>, i.e., cortical bone endplates, the cement fills nearly the entire, or in some cases the entire depth of the vertebra. The cement thereby fulfills a load bearing function between plates <NUM> and <NUM> once the cavity is filled. Put another way, since the cement is disposed through the depth of the vertebral body, it functions to prevent the bone from collapsing over time, as there is little to no bone depth without support provided by the cement. Further, even where implant <NUM> does not have plate to plate contact as shown, the plate and blade are each close enough to the cortical bone surfaces in the expanded position so that cement injected into the bone ensures that recompression of the bone is prevented or minimized following the restoration procedure. In some examples, a second implant, such as implant 100A shown in <FIG>, may be expanded in conjunction with and simultaneous to the expansion of implant <NUM>. The steps for expanding implant 100A from a collapsed position to an expanded position are the same as those for implant <NUM>.

In another implementation of the method, blade <NUM> is longer than a distance from linear longitudinal axis <NUM> of implant <NUM> to a bottom plate <NUM> of the vertebra. This circumstance may occur due to the size of the bone designated for repair or due to the placement location of the implant. In this instance, once the expansion of the implant proceeds so that tip <NUM> of blade <NUM> approaches bottom plate <NUM>, the blade begins to bend inwardly over bottom plate <NUM>, as shown in <FIG>. As shown in <FIG> and described above, blade <NUM> includes a tapered portion <NUM> toward tip <NUM> shaped so that a free end of blade <NUM> may bend when subject to a predetermined load. In some examples, the predetermined load will be determined based on an expected resistive force in a cortical bone surface to determine a load under which tapered portion <NUM> will yield. As shown in <FIG>, bending of tapered portion <NUM> prevents blade <NUM> from penetrating bottom plate <NUM>.

The preceding methods may also be performed using the implants shown in <FIG> and described above. It is noted that operation of the implants of such implementations is substantially similar to that of implant <NUM>.

In a variant of the above method, the same methodology is employed (not falling under the scope of the claimed invention) with implant <NUM>. Although operatively similar to implant <NUM>, blade <NUM> expands in an arc opposite that of blade <NUM>, and tip <NUM> of blade <NUM> moves in an arcuate manner away from central axis <NUM> toward posterior side <NUM> of vertebra <NUM> during expansion, as shown in <FIG>. Due to the width and the length of the blade being close to that of the overall implant, a volume of cancellous bone below the implant displaced by the blade during expansion of the implant is maximized using implant <NUM>. This provides a path for the cement that is as large as possible based on the implant size, thereby creating improved conditions for the flow of cement into the cavity. Because the blade rotates about an axis toward one side of the implant, the tip of the blade extends further from the longitudinal axis of the implant than it would if positioned at a more central location on the implant. Through this structure, a cavity formed in a vertebral body extends not only to an upper plate, but also close to a lower plate via expansion of the blade. During injection of cement into a cavity formed by implant <NUM>, cement flows, at least in part, through a gap between arms 552A and 552B, similarly to the cement flow path described for implant <NUM>. The method steps are otherwise common to those described for the implementations above.

In some variants, when blade <NUM> is longer than the space available in vertebra <NUM> between implant <NUM> and bottom plate <NUM>, blade <NUM> bends in a region of its tip <NUM>, as shown in <FIG>. In such instances, the tapering shape of the blade, best shown in <FIG>, and the rounded, or bulbous tip are conductive to bending when subject to loads and advanced into contact with a cortical bone surface. Further, inclusion of a blade with a recess such as that shown in <FIG> also promotes bending of the blade, and does so at a predetermined location on the blade.

In yet another variant of the method, the implant <NUM> is used (not falling under the scope of the claimed invention) for a bone repair. Implant is inserted into the vertebra and caused to be expanded as described in other implementations herein. However, because implant <NUM> includes the upper blade <NUM> and the lower blade <NUM>, either one or both blades may bend if contact is made with either top plate <NUM> or bottom plate <NUM> of vertebra <NUM>. When implant <NUM> is expanded in vertebra <NUM> as shown in <FIG>, both upper blade <NUM> and lower blade <NUM> bend upon contacting top and bottom plates <NUM>, <NUM>, respectively, and accordingly, the vertebra is not punctured. In this implementation, a second implant 700A is also implanted and expanded in the same manner as implant <NUM>, preferably simultaneously. As with the other methods previously described, cement <NUM> is injected into the void created through the expansion of the implant, as shown in <FIG>.

In any of the above method implementations, two implants may be inserted and expanded within a single vertebra or other bone, similarly to that shown for implants <NUM> in <FIG>. Each implant may be positioned relative to the other within the vertebra to maximize restoration of the vertebra when expanded.

Claim 1:
An expandable implant (<NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>) for bone restoration comprising:
a first end element (<NUM>, <NUM>, <NUM>, <NUM>, <NUM>);
a second end element (<NUM>, <NUM>, <NUM>, <NUM>, <NUM>), the second end element positioned such that a longitudinal axis (<NUM>) of the implant (<NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>) passes through a center of the first end element (<NUM>, <NUM>, <NUM>, <NUM>, <NUM>) and a center of the second end element (<NUM>, <NUM>, <NUM>, <NUM>, <NUM>);
a plate (<NUM>, <NUM>, <NUM>, <NUM>) movable in a first direction,
a blade (<NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>) movable in a second direction;
a first interconnecting element (<NUM>, 163A-B, <NUM>, 173A-B, <NUM>, 463A-B, <NUM>, 473A-B, <NUM>, 563A-B, <NUM>, 573A-B, 763A-B) extending between the plate (<NUM>, <NUM>, <NUM>, <NUM>) and at least one of the first end element (<NUM>, <NUM>, <NUM>, <NUM>, <NUM>) and the second end element (<NUM>, <NUM>, <NUM>, <NUM>, <NUM>); and
a second interconnecting element (152A-B, 182A-B, 252A-B, 452A-B, 552A-B, 752A-B) extending between the blade and a first one of the first end element (<NUM>, <NUM>, <NUM>, <NUM>, <NUM>) and the second end element (<NUM>, <NUM>, <NUM>, <NUM>, <NUM>);
wherein the implant (<NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>) is configured to be expanded from a collapsed position in which a length of the blade (<NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>) is substantially parallel to the longitudinal axis (<NUM>), to an expanded position in which the length of the blade (<NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>) is non-parallel to the longitudinal axis (<NUM>),
characterized in that
the second interconnecting element (152A-B, 182A-B, 252A-B, 452A-B, 552A-B, 752A-B) comprises an arm (152A-B, 182A-B) extending between the blade (<NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>) and the second one of the first end element (<NUM>, <NUM>, <NUM>, <NUM>, <NUM>) and the second end element (<NUM>, <NUM>, <NUM>, <NUM>, <NUM>).