Patent Description:
The invention relates in general to fixation and/or fusion surgically implanted medical devices. In particular, the invention relates to medical implantable devices with one or more integrated propulsors.

Over the years orthopedic surgeons have developed numerous implants and tools for joining boney structures together. Such fixation or joining is desirable when the boney structure is broken due to trauma or iatrogenic action. In other situations, it may be desirable to join two boney structures together to relieve nerve impingement or other medical conditions.

In many situations, boney structures are joined with medical implants which must be positioned and secured by applying impact forces. In certain situations, impact forces may cause further damage or trauma. Furthermore, the placement of an implant via impact forces may not be precise.

What is needed, therefore, is a medical implant or implantable device which does not rely solely on impact forces for positioning and placement. Such an implant is disclosed in <CIT>.

In response to these and other problems, in one embodiment, there is a medical implant comprising of one or more self-contained propulsors to position the implant within one or more boney structures.

Certain embodiments may include the above embodiments, wherein the chassis further comprises: a third arm extending laterally from the main body having a third bearing aperture defined therein; a fourth arm extending laterally from the main body having a fourth bearing aperture defined therein and extending in opposite direction from the third arm; wherein the first bearing aperture is linearly aligned with the third bearing aperture and the second bearing aperture is linearly aligned with the fourth bearing aperture; a third smooth bearing portion on the first shaft of the first propulsor, wherein the third smooth bearing portion fits within the third bearing aperture; and a fourth smooth bearing portion on the second shaft of the second propulsor, wherein the fourth smooth bearing portion fits within the fourth bearing aperture.

Certain embodiments may include the above embodiments, wherein the main body comprises a cage having a distal face and a proximal face, wherein the distal face defines an aperture for receiving bone tissue.

Certain embodiments may include the above embodiments, wherein the distal face comprises at least one member having a distal face which is shaped to cut through boney tissue during positioning.

Certain embodiments may include the above embodiments, wherein the main body comprises a cage having at least one side aperture for receiving bone tissue from a cutting action of at least one propulsor.

Certain embodiments may include the above embodiments, wherein the main body comprises a flexible region that can be biased before implantation to actively compress boney tissue after implantation.

Certain embodiments may include the above embodiments, wherein the flexible region is formed from an elastomeric material.

Certain embodiments may include the above embodiments, wherein the flexible region is formed from a shape memory alloy.

Certain embodiments may include the above embodiments, wherein the flexible region is a mechanical linkage.

Certain embodiments may include the above embodiments, wherein the chassis is fenestrated to encourage bone growth after placement.

Certain embodiments may include the above embodiments, wherein the chassis is cannulated.

Certain embodiments may include the above embodiments, wherein each propulsor comprises a distal end and a proximal end and the distal end is pointed to cut through boney tissue during positioning.

Certain embodiments may include the above embodiments, wherein each propulsor comprises a distal end and a proximal end and the distal end including a cutting surface to cut through boney tissue during positioning.

Certain embodiments may include the above embodiments, wherein each propulsor comprises a distal end and a proximal end and the proximal end includes a torque engagement feature.

Certain embodiments may include the above embodiments, wherein each propulsor comprises a distal end and a proximal end, wherein the distal end includes a forward distal thread-form shape to assist in drilling through boney tissue during implant positioning.

Certain embodiments may include the above embodiments, wherein the longitudinal axis of the first shaft of the first propulsor and the longitudinal axis of the second shaft of the second propulsor intersect at a common point forward to the implant.

Certain embodiments may include the above embodiments, wherein the longitudinal axis of the first shaft of the first propulsor and the longitudinal axis of the second shaft of the second propulsor intersect at a common point behind the implant.

Certain embodiments may include the above embodiments, wherein each propulsor is fenestrated to encourage bone growth after placement.

Certain embodiments may include the above embodiments, wherein each propulsor is cannulated.

Embodiments of the present invention may also include an insertion instrument for a surgical implant, comprising: a torque inducer having a distal and proximal end, an actuating shaft having a distal end and proximal end wherein the distal end of the torque inducer is fixedly coupled to the proximal end of the actuating shaft, a first secondary drive shaft having a proximal end and a distal end; a second secondary drive shaft having a proximal end and a distal end; and a drive train coupled to the distal end of the actuating shaft and coupled to the proximal end of the first secondary drive shaft and coupled to the proximal end of the second secondary drive shaft such that when the actuating shaft is rotated in a first direction, the first secondary drive shaft is rotated in an opposite direction and the second secondary drive shaft is rotated in the first direction.

Certain embodiments of the insertion instrument may include embodiments wherein the torque inducer comprises an elongated handle having a rotational axis aligned with a longitudinal axis of the actuating shaft.

Certain embodiments of the insertion instrument may include embodiments wherein the drive train comprises: a first spur gear fixedly coupled to a distal end portion of the actuating shaft; a second spur gear coupled to a proximal portion of the first secondary drive shaft, the second spur gear is in a first tooth meshing engagement with the first spur gear such that when the first spur gear rotates in a first rotational direction, the second spur gear rotates in a second rotational direction; a third spur gear coupled to an idler drive shaft, the third spur gear is in a second tooth meshing engagement with the first spur gear such that when the first spur gear rotates in the first rotational direction, the third spur gear rotates in the second rotational direction; and a fourth spur gear coupled to the second secondary drive shaft, the fourth spur gear is in a third tooth meshing engagement with the third spur gear such that when the third spur gear rotates in the second rotational direction, the fourth spur gear rotates in the first rotational direction.

Although not part of the claimed invention, this disclosure refers to a method of joining two boney structures together using a surgical implant, the method comprising: rotating a first propulsor of the surgical implant about the first propulsor's longitudinal axis in a first rotational direction within a first boney structure to propel an implant in a first longitudinal direction; rotating a second propulsor of the surgical implant about the second propulsor's longitudinal axis in an opposing rotational direction within a second boney structure to propel an implant in the first longitudinal direction; harvesting bone tissue from a distal side of the surgical implant into a retaining cavity of the surgical implant as the surgical implant is propelled forward, and harvesting bone tissue from at least one lateral side of the surgical implant into the retaining cavity as the surgical implant is propelled forward.

Additional embodiments of the above method may further comprising compacting the harvested bone tissue within the retaining cavity as the surgical implant is propelled forward.

Additional embodiments of the above method may further comprising compressing the first boney structure towards the second boney structure as the surgical implant is propelled in the first longitudinal direction.

Although not part of the claimed invention, this disclosure also refers to a method of joining two boney structures together using a surgical implant, the method comprising: laterally biasing a first propulsor of the surgical implant with respect to a second propulsor of the surgical implant; stabilizing the biasing of the first propulsor with respect to the second propulsor during implantation and positioning; rotating the first propulsor of the surgical implant about the first propulsor's longitudinal axis in a first rotational direction within a first boney structure to propel an implant in a first longitudinal direction; rotating a second propulsor of the surgical implant about the second propulsor's longitudinal axis in an opposing rotational direction within a second boney structure to propel an implant in the first longitudinal direction; and removing the stabilizing such that the first boney structure is laterally compressed against the second boney structure.

Although not part of the claimed invention, this disclosure further refers to a method of joining two boney structures together using a surgical implant, the method comprising: inducing a rotation in an actuating shaft; rotating a first secondary shaft in a first rotational direction as a result of rotating the actuating shaft; rotating a second secondary shaft in a second rotational direction as a result of rotating the actuating shaft; rotating a first propulsor of the surgical implant about the first propulsor's longitudinal axis in a first rotational direction within a first boney structure as a result of rotating the first secondary shaft; rotating a second propulsor of the surgical implant about the second propulsor's longitudinal axis in a second rotational direction within a second boney structure to propel an implant in the first longitudinal direction; and propelling the surgical implant in a longitudinal direction as a result of rotating the first propulsor in a first rotational direction and rotating the second propulsor in a second rotational direction.

Additional embodiments of the above method may further comprising: harvesting bone tissue from a distal side of the surgical implant into a retaining cavity of the surgical implant as the surgical implant is propelled in the first longitudinal direction, and harvesting bone tissue from at least one lateral side of the surgical implant into the retaining cavity as the surgical implant is propelled in the first longitudinal direction.

Additional embodiments of the above method may further comprising compacting the harvested bone tissue within the retaining cavity as the surgical implant is propelled in the first longitudinal direction.

These and other features, and advantages, will be more clearly understood from the following detailed description taken in conjunction with the accompanying drawings. It is important to note the drawings are not intended to represent the only aspect of the invention. The features and advantages of the present disclosure will be readily apparent to those skilled in the art.

For the purposes of promoting an understanding of the principles of the present inventions, reference will now be made to the embodiments, or examples, illustrated in the drawings and specific language will be used to describe the same. Any alterations and further modifications in the described embodiments, and any further applications of the principles of the inventions as described herein are contemplated as would normally occur to one skilled in the art to which the invention relates.

When directions, such as upper, lower, top, bottom, clockwise, counter-clockwise, are discussed in this disclosure, such directions are meant to only supply reference directions for the illustrated figures and for orientation of components in respect to each other or to illustrate the figures. The directions should not be read to imply actual directions used in any resulting invention or actual use. Under no circumstances, should such directions be read to limit or impart any meaning into the claims.

Turning now to <FIG>, there is a perspective view of one embodiment of a medical implant <NUM> comprising a chassis <NUM>, a first propulsor <NUM>, and a second propulsor <NUM>. <FIG> is a perspective view of one embodiment of the first propulsor <NUM> isolated from the chassis <NUM>. In certain embodiments, the propulsor <NUM> comprises a center longitudinal shaft <NUM> and a propeller <NUM>. In the embodiment illustrated in <FIG>, the propeller <NUM> has a clockwise thread orientation. In contrast, the propeller <NUM> of the propulsor <NUM> has a counter-clockwise thread orientation.

In certain embodiments, a distal end <NUM> of the center shaft <NUM> may be pointed or have a cutting surface defined therein to allow for easier movement of implant <NUM> through a medium, such as a boney tissue. In certain embodiments, a proximal end <NUM> of the center shaft <NUM> may have torque engagement features (not shown in <FIG>) defined therein or upon for engaging with a torque inducing device. For instance, in some embodiments, the torque engagement feature may be a <NUM> hex socket defined within the center shaft for engaging with a <NUM> hex shaped driver of an insertion instrument.

<FIG> is a perspective view of the embodiment of <FIG> where the chassis <NUM> is isolated from both the first propulsor <NUM> and the second propulsor <NUM>. In the illustrative embodiment, the chassis <NUM> comprises a center section <NUM> having a plurality of extension arms <NUM> extending from the center section <NUM>. In the illustrative embodiment, retaining rings <NUM> are formed on the outside ends of the extension arms <NUM>. In certain embodiments, retaining rings <NUM> have generally circular apertures <NUM> which form generally circular bearing surfaces sized to retain the shafts <NUM> and <NUM> of the propulsors <NUM> and <NUM>, respectively. The circular apertures <NUM> are sized to allow the shafts <NUM> and <NUM> to rotate about their longitudinal axes with respect to the chassis <NUM> while their inside faces provide a bearing surface for the shafts <NUM> and <NUM>. The lateral position of the apertures <NUM> are positioned from the center section <NUM> of the chassis to allow the propellors <NUM> and <NUM> to clear the center section <NUM> of the chassis <NUM> so that the propellors can rotate when a torque is applied to the respective propulsor <NUM> or <NUM>.

<FIG> is a top view of the implant <NUM> positioned in a medium (not shown), such as boney tissue at a moment when a clockwise rotational force is being applied to the first propulsor <NUM> while a counter-clockwise rotational force is being applied to the second propulsor <NUM>. The respective rotations cause lateral forces (indicated by arrows <NUM>, <NUM>) and longitudinal forces (indicated by arrows <NUM>, <NUM>) to be applied to the medium, respectively. The lateral forces <NUM> and <NUM> are equal in magnitude and opposite in direction. So, they effectively cancel each other. The longitudinal forces <NUM> and <NUM>, in contrast, are additive in nature and will cause the implant <NUM> to propel forward within the medium in the direction indicated by the arrow <NUM>. On the other hand, reversing the applied rotational forces or torque will cause the implant <NUM> to move in a reverse direction with respect to the medium. Thus, by changing the direction of the applied torque to the propulsors <NUM> and <NUM>, the medical implant <NUM> can be positioned precisely along a longitudinal insertion path.

Turning now to <FIG>, there is a perspective view of another embodiment of a medical implant <NUM> comprising a chassis <NUM>, a first propulsor <NUM>, and a second propulsor <NUM>. <FIG> is a perspective view of one embodiment of the first propulsor <NUM> isolated from the chassis <NUM>. In certain embodiments, the propulsor <NUM> comprises a center shaft <NUM> and a flight <NUM>. The propulsor <NUM> is similar to propulsor <NUM> discussed above except that the propeller <NUM> has been replaced with an auger thread or flight <NUM>. In certain embodiments, there may be a single flight as illustrated in <FIG>. In other embodiments, there may be two, three, or even four flights (not shown) surrounding the center shaft <NUM>. In the embodiment illustrated in <FIG>, the flight <NUM> has a clockwise thread orientation. The flight <NUM> of the propulsor <NUM> has a counter-clockwise thread orientation. In contrast to the relatively short length of the propellers <NUM> and <NUM> of the embodiment discussed above in reference to <FIG>, flights <NUM> and <NUM> are defined along most of the longitudinal lengths of the shafts <NUM> and <NUM>, respectively.

In certain embodiments, a distal end <NUM> of the center shaft <NUM> may be pointed or have a cutting surface defined therein to allow for easier movement of implant <NUM> through a medium, such as boney tissue. In certain embodiments, a proximal end <NUM> of the center shaft <NUM> may have torque engagement features (not shown in <FIG>) defined therein or upon for engaging with a torque inducing device. For instance, in some embodiments, the torque engagement feature may be a <NUM> hex socket defined within the proximal end <NUM> of the center shaft <NUM> for mating with a <NUM> hex shaped driver of an insertion instrument. In some embodiments, the center shaft may be cannulated to allow for the placement of a guidewire during the implantation process or to inject flowable materials into the cannulation, such as biologics, glues, or other osteogenic or osteroretentive material.

<FIG> is a perspective view of the embodiment of <FIG> where the chassis <NUM> is isolated from both the first propulsor <NUM> and the second propulsor <NUM>. In the illustrative embodiment, the chassis <NUM> comprises a center cage <NUM> having a plurality of extension arms <NUM> extending from the center cage <NUM>. Generally circular apertures <NUM> are defined at the ends of the extension arms <NUM> to retain the shafts <NUM> and <NUM> of the propulsors <NUM> and <NUM>, respectively. The circular apertures <NUM> are sized to allow the shafts <NUM> and <NUM> to rotate about their longitudinal axes with respect to the chassis <NUM> while their inside faces provide a bearing surface for the shafts <NUM> and <NUM>. The lateral position of the apertures <NUM> from the center cage <NUM> allow the flights <NUM> and <NUM> to clear the center cage so that the flights can rotate when torque is applied to the respective propulsor <NUM> or <NUM>.

In certain embodiments, bearing surfaces or detents <NUM> or other such features may be defined in the proximal side <NUM> of the chassis <NUM> to allow an insertion instrument to rigidly hold the chassis <NUM>. In yet other embodiments, a propulsor interfacing/retaining feature of the chassis may be comprised of a bearing block, a coupling mechanism, or other common drive transmission coupling feature.

In certain embodiments, the distal end of the chassis <NUM> has an aperture or open mouth <NUM> which allows for the harvesting of the bone tissue as the implant <NUM> moves forward through the boney tissue. In some embodiments, one or more of the members forming the distal end of the chassis may be pointed or sharpened to allow the implant to more easily cut or move through bone tissue as the implant is positioned in the boney tissue. Additionally, one or more cannulations may be formed within the chassis <NUM> to allow for the placement of a guidewire during the implantation process or to inject flowable materials into the cannulation, such as biologics, glues, or other osteogenic or osteroretentive material. In yet, other embodiments, the chassis <NUM> may be fenestrated or made from porous materials to allow for bone growth in and around the chassis.

<FIG> is a top view of the implant <NUM> positioned in a medium (not shown), such as boney tissue, at a moment when a clockwise rotational force is being applied to the first propulsor <NUM> while a counter-clockwise rotational force is being applied to the second propulsor <NUM>. As explained above in reference to <FIG>, such forces will cause the implant <NUM> to propel forward through the boney tissue. This forward movement tends to push the boney tissue in front of the implant <NUM> through the aperture or mouth <NUM> and into a retaining cavity <NUM>. Additionally, the rotation of the flight <NUM> about the shaft <NUM> also cuts through the boney tissue on the exterior side <NUM> of the implant <NUM>. Excess boney tissue from the side <NUM> is rotated by the flight <NUM> and into the retaining cavity <NUM>. Similarly, the rotation of the flight <NUM> about the shaft <NUM> also cuts through the boney tissue on the exterior side <NUM> of the implant <NUM>. Excess boney tissue from the side <NUM> is rotated by the flight <NUM> and into the retaining cavity <NUM>. Thus, the tissue entering through the mouth <NUM> and the tissue entering through the sides by the rotation of the flights <NUM> and <NUM> "self-fill" the retaining cavity <NUM> local tissue graft material and compresses that same harvested material within the retaining cavity as the implant is propelled forward. Such self-grafting within the implant <NUM> may encourage bridging boney fusion.

As the medical implant <NUM> advances further along its intended insertion path, additional boney tissue is harvested into the retaining chamber as explained above. The additional harvesting or filling of the retaining cavity <NUM> may cause a compaction of the boney tissue inside of the retaining cavity.

<FIG> is a perspective view of an alternative embodiment of a chassis <NUM> which may be used in various embodiments of the present invention. <FIG> is a partial front view of the chassis <NUM> illustrating the distal end. Chassis <NUM> is similar to the chassis <NUM> except one or more of the distal extension arms may be modified to allow for easier placement of the propulsors within the apertures of the extension arms. For brevity and clarity, a description of those parts which are identical or similar to those described in connection with chassis <NUM> will not be repeated here. Reference should be made to the foregoing paragraphs with the following description to arrive at a complete understanding of chassis <NUM>. As illustrated in <FIG>, the chassis <NUM> has three extension arms 306a-306c which are similar to extension arms <NUM> discussed above. However, the chassis <NUM> has a modified extension arm <NUM> which has a channel <NUM> defined therein from an exterior face of the arm to an interior aperture or retaining space <NUM>. The channel <NUM> may be narrower towards the exterior face and larger towards the retaining space <NUM>. In certain embodiments, an edge clip <NUM> may be formed in the wall of the extension arm <NUM> adjacent to the channel <NUM>. In certain embodiments, the edge clip may have a rounded edge <NUM>.

When assembling an implant, a proximal end of a propulsor, such as propulsor <NUM> (not shown) may be inserted into the aperture 306c. A portion of the distal end of the propulsor may be then be inserted into the channel <NUM> and pushed past the edge clip <NUM> until it is fully seated within the retaining space <NUM>. The edge clip <NUM> and the tapering of the channel <NUM> then prevents the propulsor from backing out of the channel <NUM>. Although <FIG> only shows one modified extension arm <NUM> with a channel <NUM>, one skilled in the art would recognize that additional channels and edge clips may be defined in any one of the extension arms 306a through 306c. For instance, in certain embodiments, extension arm 306a may be modified to become a mirror image of extension arm <NUM>.

<FIG> are perspective views of an alternative embodiment of a chassis <NUM> which may be used in various embodiments of the present invention. Chassis <NUM> is similar to the chasses <NUM> and <NUM> described above except one or more of the distal extension arms may be modified to allow for easier placement of the propulsors (not shown) within the apertures of the extension arms. For brevity and clarity, a description of those parts which are identical or similar to those described in connection with chasses <NUM> and <NUM> will not be repeated here. Reference should be made to the foregoing paragraphs with the following description to arrive at a complete understanding of chassis <NUM>.

<FIG> illustrates the chassis <NUM> with a modified extension arm <NUM> in an open position or configuration. In contrast, <FIG> illustrates the extension arm <NUM> in a closed position or configuration. In certain embodiments, the extension arm <NUM> has a retaining clip <NUM> sized to allow passage of a portion of a propulsor (not shown) through an opening <NUM> when the retaining clip <NUM> is open as illustrated in <FIG>. In certain embodiments, the retaining clip <NUM> may have an edge <NUM> designed to mate with a retaining feature, such as an indent (not shown) formed on an opposing surface of the chassis <NUM>.

When assembling an implant, a proximal end of a propulsor, such as propulsor <NUM> (not shown) may be inserted into the aperture 406c. When the retaining clip <NUM> is in an open configuration such as illustrated in <FIG>, a portion of the distal end of the propulsor may be inserted into the opening <NUM> and into the retaining space <NUM>. The retaining clip <NUM> may then be closed as illustrated in <FIG> which prevents the propulsor from backing out of the opening <NUM>. Although <FIG> only shows one modified extension arm <NUM> with an opening <NUM> and retaining clip <NUM>, one skilled in the art would recognize that additional openings and clips may be defined in any one of the extension arms 406a through 406c. For instance, extension arm 406a may be modified to become a mirror image of extension arm <NUM>.

Turning now to <FIG>, there is a perspective view of another embodiment of a medical implant <NUM> illustrating a proximal end of the implant. The implant <NUM> comprises a chassis <NUM>, a first propulsor <NUM>, and a second propulsor <NUM>. Chassis <NUM> is similar to the chassis <NUM> described above except the center cage <NUM> of the chassis <NUM> tapers inwardly from the proximal end to the distal end. For brevity and clarity, a description of those parts which are identical or similar to those described in connection with chassis <NUM> will not be repeated here. Reference should be made to the foregoing paragraphs with the following description to arrive at a complete understanding of implant <NUM>. As illustrated in <FIG>, the width of the center cage <NUM> at the proximal end is greater than the width of the center cage at the distal end and the length of extension arms <NUM> remain generally the same length. Thus, when the first propulsor <NUM> and the second propulsor <NUM> are positioned within the respective apertures <NUM>, the propulsors angle toward each other and their longitudinal axes converge or intersect at a point forward to the implant. In certain embodiments, the apertures <NUM> are also angled with respect to the longitudinal axis of the implant <NUM> so that the respective bearing surfaces are generally parallel with the longitudinal axes of each respective propulsor <NUM> and <NUM>. In yet other embodiments, the propulsors angle away from each other and their longitudinal axes converge or intersect at a point behind the implant.

Note that in <FIG>, the proximal ends <NUM> of the propulsors show torque engagement features <NUM> defined therein or upon for engaging with a torque inducing device. As discussed above in reference to <FIG>, the torque engagement feature <NUM> in this exemplary embodiment may be a <NUM> hex socket defined within the proximal ends <NUM> for mating with a <NUM> hex shaped driver of an insertion instrument (not shown).

<FIG> is a perspective view of another embodiment of a medical implant <NUM>. The implant <NUM> comprises a chassis <NUM>, a first propulsor <NUM>, and a second propulsor <NUM>. The implant <NUM> is similar to the implant <NUM> described above except the implant <NUM> includes different embodiments for the propulsors. For brevity and clarity, a description of those parts which are identical or similar to those described in connection with above chasses will not be repeated here. Reference should be made to the foregoing paragraphs with the following description to arrive at a complete understanding of the medical implant <NUM>.

In the illustrative embodiment of <FIG>, each of the propulsors <NUM> and <NUM> include an additional threaded region <NUM> which is between its distal end <NUM> and a smooth bearing surface <NUM> which is enclosed by an aperture <NUM> of the distal extension arm of the chassis <NUM>. In certain embodiments, this additional threaded region <NUM> provides the requisite interaction with boney tissue to propel the implant <NUM> forward until the flight <NUM> can interact with the boney tissue as described above in reference to other embodiments.

<FIG> also illustrates an alternative proximal aperture <NUM> defined in the proximal side <NUM> of the chassis <NUM>. In certain embodiments, the proximal aperture <NUM> allows for supplemental fixation, such as a screw or nail (not shown) to anchor the implant <NUM> in place after positioning.

<FIG> is a perspective view of an alternative embodiment of a medical implant <NUM> in a first or relaxed configuration. <FIG> is an isometric view of the medical implant <NUM> in a second or tensioned configuration. The medical implant <NUM> is similar to the implants described above except that the center chassis has a flexible region which allows the chassis to be "pre-tensioned" or biased prior to insertion and positioning. For brevity and clarity, a description of those parts which are identical or similar to those described above will not be repeated here. Reference should be made to the foregoing paragraphs with the following description to arrive at a complete understanding of the implant <NUM>.

In the illustrative embodiment, the implant <NUM> comprises a chassis <NUM>, a first propulsor <NUM>, and a second propulsor <NUM>. In certain embodiments, the chassis <NUM> comprises a first outside ridged portion <NUM> and a second outside ridged portion <NUM>. A flexible interior region or portion <NUM> couples the first ridged portion <NUM> to the second ridged portion <NUM>. In the illustrative embodiment, the flexible interior portion comprises a first or distal flexible member <NUM> and a second or proximal flexible member <NUM>. In other embodiments, there may be a single flexible member (not shown). In certain embodiments, the flexible members may comprise an elastomeric material, such as Ethylene Propylene Diene Monomer ("EPDM"), Perfluoroelastomer (FFKM), Fluoroelastomer (FKM), or Nitrile.

In <FIG>, both the distal and proximal flexible members are in a first or "relaxed" configuration such that the first propulsor <NUM> and the second propulsor <NUM> are spaced at a distance D1 from each other. In <FIG>, both the distal and proximal flexible members are in a second or "tensioned" configuration such that the first propulsor <NUM> and second propulsor <NUM> are spaced at a distance D2 from each other. As illustrated, length D2 is greater than the length D1 which causes the flexible members to be stretched or biased. Such stretching or biasing can occur when the implant <NUM> is positioned onto an inserter and or when guide holes are drilled into the boney material at a length D2 from each other. Once the flexible members are stretched or pre-tensioned so that the propulsors are at a distance D2 from each other, the implant <NUM> may be inserted and positioned into the boney tissue and the inserter removed. Such pre-tensioning or biasing will cause the two boney structures to actively compress against each other as the flexible members attempt to return to a first or relaxed configuration.

In other embodiments, the flexible interior portion may form a mechanical linkage (such as a scissor linkage), which after implantation, may be mechanically actuated to expand or compress the surrounding boney tissue.

In yet other embodiments, the flexible interior portion <NUM> may be made from nickel titanium (also known as Nitinol®) or another shape memory alloy. The flexible portion <NUM> would have a specific shape (i.e., a straight or linear shape) at a cooler temperature, such as room temperature. Once inserted into a human body, the metal would rise to a body temperature which will cause the anchor to change shape (i.e., to change from a linear shape to a curve shape) to enhance compression.

Turning now to <FIG>, there is a perspective view of another embodiment of a medical implant <NUM> illustrating a proximal end of the implant. The implant <NUM> comprises a chassis <NUM>, a first propulsor <NUM>, and a second propulsor <NUM>. Chassis <NUM> is similar to the chassis <NUM> described above. In this illustrated embodiment, the first and second propulsors <NUM> and <NUM> are fenestrated with a plurality of apertures <NUM> to encourage bone growth through the propulsors after positioning and placement. For brevity and clarity, a description of those parts which are identical or similar to those described in connection with the implants discussed above will not be repeated here. Reference should be made to the foregoing paragraphs with the following description to arrive at a complete understanding of the implant <NUM>. Such an implant <NUM> may be suited for small boney interfaces where a larger center cage would be obtrusive to the surgical outcome.

<FIG> is an isometric view of an alternative embodiment of a medical implant <NUM> which does not fall under the claimed invention. The implant <NUM> comprises a longitudinal chassis or cage <NUM> and a single propulsor <NUM> centered on the longitudinal axis <NUM> of the chassis <NUM>. For brevity and clarity, a description of those parts which are identical or similar to those described in connection with the implants discussed above will not be repeated here. Reference should be made to the foregoing paragraphs with the following description to arrive at a complete understanding of the implant <NUM>.

The exemplary cage <NUM> comprises a distal triangular plate <NUM> and a proximal triangular plate <NUM>. The distal triangular plate <NUM> defines a center aperture <NUM> sized to allow a center shaft <NUM> of the propulsor <NUM> to rotate about the longitudinal axis <NUM>. Similarly, the proximal triangular plate <NUM> defines a center aperture (not shown) which is also sized to allow the center shaft <NUM> of the propulsor <NUM> to rotate about the center axis <NUM>.

In the illustrative embodiment, there are three longitudinal legs <NUM> joining the distal triangular plate <NUM> to the proximal triangular plate <NUM>. The lateral distance of the legs <NUM> from the longitudinal axis <NUM> are spaced such that the legs clear a rotating flight <NUM> of the propulsor <NUM>, but are close enough to still allow an interaction between the flight <NUM> and the surrounding boney tissue (not shown) so that rotating the flight <NUM> of the propulsor <NUM> propels and positions the entire implant <NUM> as described above with respect to other embodiments.

In certain embodiments the implants (such as implant <NUM>) may be manufactured utilizing 3D printing where the implant is printed as a relatively complete assembly incorporating the propulsors <NUM>, <NUM> and various versions of the chassis. Such embodiments may then be finalized with standard machining methods to clean-up or add various surfaces and features. In yet other embodiments, the chassis or propulsors, may be separated into multiple pieces so that they may be assembled to form a complete implant. The assembled component pieces may then be joined by manufacturing methods, such as but not limited to pinning, gluing, welding, crimping, or snap-fit.

In other embodiments, the chasses may be cannulated to allow the implant to be guided using a surgical guide wire during the implantation process or to inject flowable materials into the cannulation, such as biologics, glues, or other osteogenic or osteroretentive material. In yet, other embodiments, the chassis of the various embodiments may be fenestrated or made from porous materials to allow for bone growth in and around the chassis.

In certain embodiments, the implants and propulsors discussed above may be fabricated from any number of biocompatible implantable materials, including but not limited to Titanium Alloys (Ti 6AI4V ELI, for example), commercially pure titanium, Chromium Cobalt (Cr-Co) and/or stainless steels. In yet other embodiments, the implants and propulsors may also be manufactured from polymer, including Carbon Fiber Reinforced Polymer ("CFRP") with a high carbon mass percentage. In some embodiments, the implants (or portions of the implants) may be coated with a bone conducting surface treatment to increase the potential of bone on-, through-, or in-growth.

In certain embodiments, aspects of the invention may include a surgical kit comprising multiple implants of different size ranges.

One skilled in the art would recognize that individual features discussed in connection with certain exemplary chasses and propulsors described above may be combined with the features of other chasses and propulsors. Such combinations are still within the inventive concept described herein.

<FIG> is a perspective view of an assembled insertion instrument <NUM> from a distal perspective. <FIG> is a perspective view of the assembled insertion instrument <NUM> from a proximal perspective. <FIG> is a perspective view of the exploded insertion instrument <NUM> from a distal perspective. <FIG> is a perspective view of the exploded insertion instrument <NUM> from a proximal perspective.

In certain embodiments, a handle <NUM> or another torque inducing mechanism is positioned at the proximal end of the insertion instrument <NUM>. The handle <NUM> is fixedly coupled to a proximal end of a longitudinal primary or actuating shaft <NUM>. In certain embodiments, the actuating shaft <NUM> is coupled to a drive train <NUM> which: (<NUM>) transmits the torque and/or rotation from the actuating shaft to induce torque and/or rotation in a first rotational direction to a first secondary shaft <NUM>, and (<NUM>) to induce torque and/or rotation in an opposite rotational direction to a second secondary shaft <NUM>. In certain embodiments, distal ends <NUM> and <NUM> of the first and second secondary shafts ends are shaped to mate with a torque engagement feature of the propulsors of an implant as described above. For instance, in the illustrative embodiment, the distal ends <NUM> and <NUM> of the secondary shafts <NUM> and <NUM> are sized and shaped to mate with a <NUM> hex socket defined within the proximal ends of the propulsors as described above.

In certain embodiments, the drive train <NUM> comprises a four in-line spur gears <NUM>, <NUM>, <NUM> and <NUM> aligned in a lateral direction as best illustrated in <FIG>. In the illustrative embodiment, spur gear <NUM> is fixedly coupled to the actuating shaft <NUM>, spur gear <NUM> is fixedly coupled to the first secondary shaft <NUM>, spur gear <NUM> is fixedly coupled to an idler shaft <NUM> (see <FIG>), and spur gear <NUM> is fixedly coupled to the second secondary shaft <NUM>. In other embodiments, the drive train <NUM> may be composed of belts, drive shafts, chain, and/or shaft couplers.

A mounting unit <NUM> comprises an alignment plate <NUM> at its proximal end which couples to and interacts with the shafts <NUM>, <NUM>, <NUM>, and <NUM>. In the illustrative embodiment, four alignment apertures 936a-936d are defined within the alignment plate <NUM> as best illustrated in <FIG>. The four alignment apertures 936a-936d laterally align: the actuating shaft <NUM>, the first secondary shaft <NUM>, the second secondary shaft <NUM>, and the idler shaft <NUM>. In certain embodiments, retaining rings and corresponding indents within the alignment apertures 936a-936d retain and keep the shafts longitudinally positioned but allow the shafts to rotate with respect to the alignment plate <NUM>.

At the distal end of the mounting unit <NUM>, there are two retaining arms <NUM> extending in a lateral direction from the main body of the mounting unit <NUM>. In certain embodiments, two supporting apertures 940a and 940b are defined within the retaining arms <NUM> as best illustrated in <FIG> and <FIG>. When the insertion tool is assembled, the first secondary shaft <NUM> extends through alignment aperture 936d and through the supporting aperture 940b and can rotate freely with respect to both apertures. Similarly, the second secondary shaft <NUM> extends through alignment aperture 936a and through the supporting aperture 940a and can rotate freely with respect to both of these apertures.

In certain embodiments, there may be a plurality of retaining features, such as a plurality of fingers <NUM> which correspond to bearing surfaces or detents defined in the proximal side of the chassis of the medical implants to allow the insertion instrument <NUM> to rigidly hold the medical implants described above.

In certain embodiments, the handle <NUM> is designed to impart a torque or rotation on the actuating shaft <NUM> when a user turns the handle <NUM>. If necessary, the user may also hold the mounting unit <NUM> or the alignment plate <NUM> to provide stability and countertorque when the handle <NUM> is turned during insertion and deployment of the implants. As the actuating shaft <NUM> rotates, for instance in a clockwise direction, the spur gear <NUM> will also rotate in a clockwise direction. The clockwise rotation of spur gear <NUM> will cause a counter clockwise rotation of spur gear <NUM> which will cause the counter clockwise rotation of the first secondary shaft <NUM>. Additionally, the clockwise rotation of the spur gear <NUM> will also cause a counter-clockwise rotation of spur gear <NUM> which, in turn, causes the clockwise rotation of spur gear <NUM>. Because spur gear <NUM> is rigidly coupled to the second secondary shaft <NUM>, the clockwise rotation of the spur gear <NUM> will cause the rotation of the second secondary shaft <NUM>. Thus, as the handle <NUM> is rotated in a clockwise direction, the first secondary shaft <NUM> rotates in a counter-clockwise rotation and the second secondary shaft <NUM> rotates in a clockwise rotation.

Referring now to <FIG>, the manner of using one embodiment of the present invention will now be described. <FIG> is a flowchart illustrating a surgical method <NUM> for inserting and positioning certain embodiments of the present invention. The method starts in step <NUM> and flows to step <NUM> where a surgical site is selected and prepared for insertion. In certain embodiments, a surgical site may be a facture between two boney structures. For example, <FIG> is a conceptual perspective illustration depicting a surgical site <NUM> comprising two boney elements <NUM> and <NUM> which have been selected to be fused together. In <FIG> both boney elements <NUM> and <NUM> have been pre-drilled, indicated by bores <NUM> and <NUM>. In other embodiments, drilling of the bores <NUM> and <NUM> may not be necessary. In this illustrative embodiment, the diameter of the bores <NUM> and <NUM> are undersized relative to the shaft diameters of the propulsors in the implant to be inserted.

<FIG> is a conceptual perspective illustration of the surgical site <NUM> illustrating where a bone saw was also used to resect a small area <NUM> between the bores <NUM> and <NUM> which may be used as an insertion channel for various embodiments of the medical implants described above. In certain embodiments, resection may not be necessary or desirable. In certain situations, the resection is undersized relative to the chassis height of the medical implant.

In other situations, there may be a gap (not shown) between the boney elements <NUM> and <NUM> of the surgical site <NUM>. In such situations, passive or active compression techniques may be used to close the gap between the boney structures as discussed above.

Referring back to <FIG>, in step <NUM>, an implant, such as implant <NUM> (described above) may be coupled to the insertion instrument <NUM> as illustrated in <FIG>. In certain embodiments, the coupling may be made during the manufacturing process if the insertion instrument <NUM> is designed to be a single use instrument packed in a sterile container. If the insertion instrument is designed to be a multi-use instrument, then the implant <NUM> may be coupled to the insertion instrument <NUM> prior to insertion and after the selection of the desired size of the implant. As one skilled in the art would recognize, the distance between the centers of the bores <NUM> and <NUM> should be roughly the same as the distance between the longitudinal axes of the propulsors of the selected medical implant.

Once the medical implant is coupled to the insertion instrument, in step <NUM>, the insertion instrument can then be aligned and introduced into the bores <NUM> and <NUM> of the surgical site <NUM> (in embodiments where pre-drilled bores are necessary or required). In certain embodiments, surgical guidewires may be used to assist in guiding the implant to the desired location. Once aligned, the user may actuate the propulsors within the implant (step <NUM>) by turning the handle <NUM> relative to the mounting unit <NUM> (<FIG>). As explained above, the rotation of the handle <NUM> will cause the first secondary shaft <NUM> to rotate in one direction and will also cause the second secondary shaft <NUM> to rotate in an opposite direction. In turn, the rotation of the first secondary shaft <NUM> will induce a torque and/or rotation by the propulsor <NUM> (See <FIG>) in the first direction. Similarly, the rotation of the second secondary shaft <NUM> will induce a torque and/or rotation by the propulsor <NUM> (See <FIG>) in the opposite direction.

As explained in reference to <FIG> and <FIG> above, the respective rotations of the propulsors <NUM> and <NUM> will propel the medical implant <NUM> into the boney structures until the medical implant reaches the desired location. If for some reason, the medical implant <NUM> needs to be repositioned during the surgical procedure, the user can turn the handle <NUM> in an opposite direction - which will cause the implant to reverse direction within the boney tissue so that exact positioning can occur.

As also explained above in reference to <FIG>, as the medical implant <NUM> moves forward through the boney tissue, the tissue entering through the mouth <NUM> and the tissue entering through the sides by the rotation of the flights <NUM> and <NUM> "self-fill" the retaining cavity <NUM> with local tissue graft material and compresses harvested material within the retaining cavity <NUM> (step <NUM>).

In certain embodiments with passive or active compression features, such as the embodiments discussed above in reference to <FIG> and <FIG>, the forward movement of the implant <NUM> through the boney tissue may also cause compression between the boney elements <NUM> and <NUM> (step <NUM>). In situations where there is a gap between the boney structures, such compression features may close the gap between the boney structures.

Once the medical implant <NUM> is in the desired location, in step <NUM>, the medical implant <NUM> may be decoupled from the insertion instrument <NUM>. In certain embodiments the decoupling may entail pulling on the insertion instrument <NUM> with enough force to overcome the retaining force on the implant <NUM> provided by the retaining fingers <NUM> (see also <FIG>). In step <NUM>, the surgical site can then be closed in a traditional manner and the process finishes in step <NUM>.

As can be seen from the above discussion, there is an active relationship between the various embodiments of the chasses and propulsors that causes the various embodiments to be able to be inserted without the use of impaction.

During implant insertion, the action of the propulsor's rotation compresses the boney elements together. This compression in turn produces a material boney element alignment. Furthermore, in certain embodiments, the rotation of the propulsors forces the implant to actively harvest graft into the implant's graft chamber. Continued rotation of the flight of each propulsor also compresses the graft material within this chamber.

Furthermore, in certain embodiments, the angular momentum of the flights channels compressed material between and within the flight element itself.

The various embodiments described here may be used anywhere in the body for joining or fixating one or more boney elements, such as but not limited to joint spaces, a break resultant from trauma, a break resultant from iatrogenic action, or across or within a singular bone which needs to be stabilized or strengthened.

The abstract of the disclosure is provided for the sole reason of complying with the rules requiring an abstract, which will allow a searcher to quickly ascertain the subject matter of the technical disclosure of any patent issued from this disclosure. It is submitted with the understanding that it will not be used to interpret or limit the scope or meaning of the claims.

Any advantages and benefits described may not apply to all embodiments of the invention. When the word "means" is recited in a claim element, Applicant intends for the claim element to fall under <NUM> USC <NUM>(f). Often a label of one or more words precedes the word "means". The word or words preceding the word "means" is a label intended to ease referencing of claims elements and is not intended to convey a structural limitation. Such means-plus-function claims are intended to cover not only the structures described herein for performing the function and their structural equivalents, but also equivalent structures. For example, although a nail and a screw have different structures, they are equivalent structures since they both perform the function of fastening. Claims that do not use the word "means" are not intended to fall under <NUM> USC <NUM>(f).

Claim 1:
A surgical implant (<NUM>,<NUM>,<NUM>,<NUM>,<NUM>,<NUM>,<NUM>) comprising:
a chassis (<NUM>,<NUM>,<NUM>,<NUM>,<NUM>,<NUM>,<NUM>) comprising,
a main body positioned along a longitudinal axis;
a first arm extending laterally from a side of the main body having a first bearing aperture (<NUM>,<NUM>,<NUM>) defined therein;
a second arm extending laterally from the main body on an opposing side of the main body, the second arm having a second bearing aperture (<NUM>,<NUM>,<NUM>) defined therein;
a first propulsor (<NUM>) comprising,
a first longitudinal shaft (<NUM>) having a first rotational axis; a clockwise auger flight (<NUM>,<NUM>) positioned about a portion of the first longitudinal shaft,
a first smooth bearing portion of the first longitudinal shaft;
wherein the first smooth bearing portion fits within the first bearing aperture;
wherein the first longitudinal shaft is positioned a first lateral distance from the main body of the chassis such that a rotation of the clockwise auger flight clears the main body;
a second propulsor (<NUM>) comprising,
a second longitudinal shaft having a second rotational axis;
a counter-clockwise auger flight (<NUM>) positioned about a portion of the second longitudinal shaft,
a second smooth bearing portion of the second longitudinal shaft;
wherein the second smooth bearing portion fits within the second bearing aperture; and
wherein the second longitudinal shaft is positioned a second lateral distance from the main body of the chassis such that a rotation of the counter-clockwise auger flight clears the main body.