Patent Description:
The vertebrate spine is the axis of the skeleton providing structural support for the other parts of the body. Adjacent vertebrae of the spine are supported by an intervertebral disc, which serves as a mechanical cushion permitting controlled motion between vertebral segments of the axial skeleton.

The spinal disc can be displaced or damaged due to trauma, disease, degenerative defects or wear over an extended period of time. To alleviate back pain caused by disc herniation or degeneration, the disc can be removed and replaced by an implant that promotes fusion of the remaining bone anatomy. The implant, such as a spacer or cage body, should be sufficiently strong to support the spine under a wide range of loading conditions.

<CIT> and <CIT> both disclose intervertebral implants known in the art.

There remains a need for improved implants that facilitate intervertebral fusion and serve as a means to restore intervertebral height and/or lordosis.

To meet this and other needs, intervertebral implants and systems are provided. The implant may feature a pivoting mechanism housed within the spacer. The pivoting mechanism allows for the implant to be inserted into in the disc space in a first, initial position and then subsequently pivoted into a second, final position. The ability to articulate the implant in-situ allows the surgeon to safely navigate past the posterior neural elements and/or optimize the implant placement relative to the patient anatomy.

The implant may also feature a central lumen to house bone graft material. It is through this central lumen where most of the fusion may occur. The implants of the disclosure incorporate a volumetric, interconnected porosity throughout the entire spacer. This enables bone to grow into and/or through the spacer, making it part of the fusion mass. The incorporation of a volumetric, interconnected porosity within the implant may encourage faster, stronger intervertebral fusion.

The implant may be constructed by typical manufacturing processes (e.g., manufactured from a titanium alloy) or may be constructed by additive manufacturing, such as 3D printing. The additive manufacturing may incorporate a volumetric, interconnected porosity through the entire spacer or a portion thereof. The porosity may enable bone growth into the spacer, thereby making it part of the fusion mass and encouraging a faster and/or stronger fusion.

According to the invention it is provided an intervertebral implant having the features of claim <NUM>. Further advantageous aspects of the invention are set forth in the dependent claims.

According to one embodiment, an intervertebral implant for implantation in an intervertebral space between vertebrae is disclosed. The implant includes an implant body, a pivoting member, and a blocking member. The implant body extends from an upper surface to a lower surface. The implant body has a front end, a rear end and a pair of spaced apart first and second side walls extending between the front and rear ends such that an interior chamber is defined within. The rear end includes an elongated opening defining at least one track and a dimple. The pivoting member includes an enlarged head portion and an elongated shaft portion terminating at a distal end. The distal end of the pivoting member is positioned within the dimple and the enlarged head portion is positioned within the at least one track. The blocking member extends from the upper surface to the lower surface of the implant body and secures the pivoting member within the at least one track. The pivoting member is configured to slide along the at least one track and articulate from an initial position to a final position. The dimple may act as a pivot point for the pivoting member, and the at least one track may extend along an arc having a constant radius from the pivot point.

It is further disclosed but does not form part of the invention, a method of forming an intervertebral implant for implantation in an intervertebral space between vertebrae is provided. The method includes utilizing a 3D printing process to deposit individual layers. The layers may contain solid and porous portions, which ultimately define the overall shape and design of the device. The at least one track may be further finished using a dovetail cutter having a curved cutting surface configured to form a smooth vertical region for the at least one track.

It is further disclosed but does not form part of the invention, a method of assembling the implant may include aligning the distal tip of the pivoting member a gap in the at least one track along an axis. The pivoting member is seated within the implant, but is not yet engaged with the at least one track. The pivoting member is articulated into a neutral position, into alignment with the at least one track, and exposing an opening to receive the blocking member. The blocking member is installed in the opening, thereby preventing the blocking member from being removed from the implant body. Once installed, the pivoting member may articulate, in-situ, along the at least one track into the final, implanted position.

A more complete understanding of the present disclosure, and the attendant advantages and features thereof, will be more readily understood by reference to the following detailed description when considered in conjunction with the accompanying drawings wherein:.

Embodiments of the disclosure are generally directed to intervertebral implants and systems. The implants can be used to fuse together a treated area of the spine while restoring and/or maintaining the proper spacing and natural curvature of the spine. The treated area can include regions between adjacent vertebral bodies so that the height of the implant corresponds approximately to the height of the disc. The implants described herein may be configured to articulate with ease into a desired position in between the two vertebrae.

Referring now to <FIG>, one embodiment of a transforaminal lumbar interbody fusion (TLIF) implant assembly <NUM> will be described. As illustrated, the implant <NUM> has a body <NUM> in the form of a generally banana-style cage. The body <NUM> is defined by a tapered front end <NUM>, a rear end <NUM> and side walls <NUM> and <NUM> extending therebetween. In particular, side walls <NUM> and <NUM> may be curved, such that side wall <NUM> is concave and side wall <NUM> is convex. The front end <NUM> may be tapered to ease insertion into the disc space, and rear end <NUM> may be convexly curved. A hollow interior chamber <NUM> may be defined within the body <NUM>. The hollow interior chamber <NUM> may be configured to receive bone growth promoting materials, for example, such as autogenous and/or allograft bone. The implant <NUM> has an upper surface <NUM> and a lower surface <NUM>. The upper and lower surfaces <NUM>, <NUM> may be substantially parallel or otherwise configured to provide the proper intervertebral spacing. The upper and lower surfaces <NUM>, <NUM> may define a plurality of teeth, ridges, or serrations <NUM>. In some embodiments, the serrations <NUM> may be defined only by the solid support structure (e.g., near the rear end <NUM>) or by both the solid support structure <NUM> and the porous structure <NUM> (e.g., in a central region of the implant <NUM>). The serrations <NUM> may be configured to provide migration resistance of the implant <NUM>. The leading, front end may be smooth, tapered, and free of teeth or serrations.

The rear end <NUM> of the implant <NUM> includes an elongated opening <NUM> between the upper and lower surfaces <NUM>, <NUM> for receiving a pivoting member <NUM>. The elongated opening <NUM> ma curved to follow the outer contour of the convexly curved rear end <NUM>. As best seen in <FIG>, the pivoting member <NUM> includes an enlarged head portion <NUM> and an elongated shaft portion <NUM> extending therefrom. The elongated shaft portion <NUM> may terminate at a distal end <NUM>, which may be rounded, pointed, or otherwise configured. The distal end <NUM> may be configured to be received within a female dimple <NUM> within the opening <NUM>, which acts as a pivot point for the pivoting member <NUM>. The exterior shaft portion <NUM> of the pivoting member <NUM> may be non-threaded and smooth or otherwise configured. The head portion <NUM> of the pivoting member <NUM> may include an instrument receiving recess <NUM> and the instrument receiving recess <NUM> may extend into the shaft portion <NUM> of the pivoting member <NUM>, thereby forming a blind hole. In one embodiment, the portion of the receiving recess <NUM> extending into the shaft portion <NUM> of the pivoting member <NUM> may be internally threaded, for example, to engage an externally threaded instrument (not shown). The head portion <NUM> of the pivoting member <NUM> may be rounded, contoured, notched, or otherwise configured to be received within track or tracks <NUM> defined in the opening <NUM>.

The elongate opening <NUM> within the rear end <NUM> of the implant <NUM> may extend a depth into the implant <NUM> to form a blind recess. The elongated opening <NUM> may further define one or more tracks <NUM>. The track <NUM> may define a female recess having a length greater than its width. The track <NUM> may be curved to mimic the outer surface of the implant <NUM>. The one or more tracks <NUM> may be positioned proximate to the upper and/or lower surfaces <NUM>, <NUM> of the implant <NUM>. In an exemplary embodiment, the elongated opening <NUM> contains a first track near the upper surface <NUM> and a second track near the lower surface <NUM> such that an upper portion of the head portion <NUM> of the pivoting member <NUM> is received in the first track <NUM> and a lower portion of the head portion <NUM> of the pivoting member <NUM> is received in the second track <NUM>. The elongated opening <NUM> may further define one or more pivoting dimples <NUM>. The pivoting dimple <NUM> may define a female indentation within the body <NUM> of the implant <NUM>. The pivoting dimple <NUM> may be centrally located within the implant <NUM>. The distal end <NUM> of the pivoting member <NUM> may be receivable within the dimple <NUM>, which acts as a pivot point for the pivoting member <NUM>. The track or tracks <NUM> may extend along an arc having a constant radius from the pivot point.

The implant <NUM> may further include a blocking member <NUM>. A throughopening <NUM> may extend from the upper surface <NUM> to the lower surface <NUM> of the implant <NUM> or a portion thereof. The blocking member <NUM> may have an elongated body and is receivable within opening <NUM>, for example, from the upper surface <NUM> to the lower surface <NUM> to secure the pivoting member <NUM> within the elongated opening <NUM> and within the track or tracks <NUM>. The blocking member <NUM> may be secured in opening <NUM> via an interference fit or friction fit or otherwise secured in the opening <NUM>.

Referring to <FIG>, a method of assembling the implant <NUM> will be described, the method is not part of the invention but it is presented for a better understanding of the invention. As shown in <FIG>, the distal tip <NUM> of the pivoting member <NUM> is aligned with a gap <NUM> in the track <NUM> along an axis A. The distal tip <NUM> may also be aligned with the pivoting dimple <NUM> along axis A. Turning to <FIG>, the pivoting member <NUM> is seated within the implant <NUM>, but is not yet engaged with the track <NUM>. The distal tip <NUM> or a portion thereof is received within the dimple <NUM> and the pivoting member <NUM> extends through the gap <NUM> and the head portion <NUM> of the pivoting member <NUM> protrudes slightly past the outer profile of the implant <NUM>. Turning to <FIG>, the pivoting member <NUM> is articulated into a neutral position and into alignment with the track <NUM>. When articulated into the neutral position, opening <NUM> is exposed to receive the blocking member <NUM>. Turning to <FIG>, the blocking member <NUM> is aligned with the opening <NUM>. As shown in <FIG>, the blocking member <NUM> is installed in the opening <NUM>, thereby preventing the pivoting member <NUM> from pivoting back along the direction it was installed from. The blocking member <NUM> also prevents the pivoting member <NUM> from falling out of the opening <NUM>. Once installed, the pivoting member <NUM> may articulate along the track or track <NUM> up to <NUM> degrees from the initial, horizontal position to the final, implanted position. The range of articulation may be limited by the track or tracks <NUM>, the blocking member <NUM>, and/or one or more stops built into the track <NUM> and/or opening <NUM>. As best seen in <FIG>, once the pivoting member <NUM> is articulated into its final position, the entire pivoting member <NUM> is housed entirely within opening <NUM> and is housed entirely within the spacer body <NUM>. In other words, no portion of the pivoting member <NUM> protrudes beyond the outer profile of the implant <NUM>. Because the pivoting member <NUM> is received completely within the opening <NUM>, the pivoting member <NUM> does not contact the adjacent endplates of the vertebral bodies.

Turning now to <FIG>, a method of inserting and installing the articulating implant <NUM> will be described, the method is not part of the invention but it is presented for a better understanding of the invention. As shown in <FIG>, the pivoting member <NUM> is in its initial, insertion position. An instrument (not shown) may be received within the instrument receiving recess <NUM> of the pivoting member <NUM>. The implant <NUM> may be installed through a transforaminal approach, for example, although any suitable installation approach may be selected by the surgeon. Once between the vertebrae, the pivoting member <NUM> may be moved along track or tracks <NUM>, in-situ, such that the implant body <NUM> pivots into its final, installed position within the disc space. Thus, the implant body <NUM> may pivot up to <NUM> degrees relative to its initial position. After the final positioning is achieved, the instrument may be removed. The ability to articulate the implant <NUM> in-situ allows the surgeon to safely navigate past the posterior neural elements and/or optimize the implant placement relative to the patient anatomy.

As shown in <FIG>, one or more radiographic markers <NUM>, <NUM>, <NUM> may be provided within the implant <NUM> in order to identify the orientation of the spacer within the disc space, for example, using X-ray or other imaging. As shown, a first radiographic marker <NUM> may be positioned centrally within the implant <NUM>. The first marker <NUM> may be positioned, for example, near the distal end <NUM> of the pivoting member <NUM>. A second radiographic marker <NUM> may be positioned near the upper surface <NUM>, and a third radiographic marker <NUM> may be positioned near the lower surface <NUM> of the implant <NUM>. The markers <NUM>, <NUM>, <NUM> may be generally cylindrical in shape. In addition, the second and third markers <NUM>, <NUM> may be shorter in length than the first marker <NUM>. Although this configuration is shown, it will be envisioned that any suitable location, spacing, shape, and size of the markers may be selected.

After the implant <NUM> has been articulated into position within the disc space, the proper positioning of the implant <NUM> can be ascertained, as best seen in <FIG>, by generally coaxially aligning the first marker <NUM> with the second and third markers <NUM>, <NUM> respectively. <FIG> depicts what a radiographic image would look like when the implant is about <NUM> degrees under-rotated, and <FIG> depicts a radiographic image when the implant <NUM> is about <NUM> degrees under-rotated. Thus, a surgeon observing no alignment between the markers <NUM>, <NUM>, <NUM> would know that the implant <NUM> was not fully articulated into its final position. Furthermore, one could ascertain by looking at the imaging that a larger gap G between the first marker <NUM> and the second and third markers <NUM>, <NUM> (e.g., shown in <FIG>) would represent that the implant <NUM> is further out of position than a smaller gap G between the first marker <NUM> and the second and third markers <NUM>, <NUM> (e.g., shown in <FIG>). In other words, the surgeon would know that the implant is moving in the correct direction as gap G becomes smaller and the markers <NUM>, <NUM>, <NUM> are ultimately aligned in the final implant position (shown in <FIG>).

The implants of the disclosure may be manufactured from traditional manufacturing processes (machining) or those later developed. In one embodiment, the implants are made by additive manufacturing or 3D printing. Various forms of additive manufacturing, or 3D printing, have been developed which allow structures to be formed layer by layer. One illustrative 3D printing technology is Direct Metal Laser Sintering (DMLS) wherein parts are built using a laser to selectively sinter (heat and fuse) a powdered metal material into layers. The process begins once a 3D CAD file is mathematically sliced into multiple 2D cross sections and uploaded into the system. After the first layer is produced, the build platform is lowered, another powder layer is spread across the plate, and the laser sinters the second layer. This process is repeated until the part is complete. Layer-by-layer manufacturing allows for the direct fabrication of complex parts that would be cost-prohibitive, and often impossible, to produce through traditional manufacturing processes. The powder layer thickness used during the fabrication of the spacers may be as thin at <NUM>, for example. The resolution of the laser may be as fine as <NUM>, for example. Although it is envisioned that any suitable thickness or laser resolution may be used or selected.

The disclosure is not limited to DMLS, but various 3D printing methods may be utilized. For example, VAT photopolymerization utilizes a vat of liquid photopolymer resin which is cured through selective exposure to light (via a laser or projector) which then initiates polymerization and converts the exposed areas to a solid part. As another example, Powder Bed Fusion, of which DMLS is a subcategory, utilizes powdered materials which are selectively consolidated by melting it together using a heat source such as a laser or electron beam. The powder surrounding the consolidated part acts as support material for overhanging features. As yet another example, in Binder Jetting Liquid bonding agents are selectively applied onto thin layers of powdered material to build up parts layer by layer. The binders include organic and inorganic materials. Metal or ceramic powdered parts are typically fired in a furnace after they are printed. Material Jetting is another example of a 3D printing process which may be utilized wherein droplets of material are deposited layer by layer to make parts. Common varieties include jetting a photocurable resin and curing it with UV light, as well as jetting thermally molten materials that then solidify in ambient temperatures. As another example, in Sheet Lamination sheets of material are stacked and laminated together to form an object. The lamination method can be adhesives or chemical (paper/plastics), ultrasonic welding, or brazing (metals). Unneeded regions are cut out layer by layer and removed after the object is built. Another example of a 3D printing process that may be utilized is Material Extrusion wherein material is extruded through a nozzle or orifice in tracks or beads, which are then combined into multi-layer models. Common varieties include heated thermoplastic extrusion and syringe dispensing. Yet another example is Directed Energy Deposition wherein powder or wire is fed into a melt pool which has been generated on the surface of the part where it adheres to the underlying part or layers by using an energy source such as a laser or electron beam. Although these 3D printing techniques are exemplified, it will be appreciated that any suitable techniques may be selected to build the implant designs.

The implants may also be manufactured utilizing a combination of additive manufacturing processes and other manufacturing processes, for example, machining or laser etching. Additionally, the implants may be processed during and/or after manufacture utilizing various techniques, for example, abrasion, machining, polishing, or chemical treatment. The implants may be manufactured from various materials, such as biocompatible materials, including metals, polymers, ceramics or combinations thereof. Exemplary materials include Titanium (and Titanium alloys), Cobalt-Chrome, PEEK, and/or Stainless Steel, for example.

Turning to <FIG>, a 3D printed implant <NUM> is shown having a solid support structure <NUM> (shown as light portions) and a porous structure <NUM> (shown as dark portions) formed integral therewith. The configuration of the solid structure <NUM> is selected to provide the implant sufficient structural integrity and mechanical stability while maximizing the area of porous structure <NUM> which facilitates better integration/incorporation with the adjacent bone. The configuration of the support structure <NUM> and the porous structure <NUM> may be selected, for example, to provide the implant with an adequate construct strength while maximizing the potential for bony in-growth and allowing for clear radiographic imaging.

As shown in <FIG>, the solid structure <NUM> may form a frame or support structure for the porous structure <NUM>. The solid structure <NUM> may include an outer wall portion <NUM> and an inner wall portion <NUM>. One or more cross-struts <NUM> may be provided between the outer and inner wall portions <NUM>, <NUM>. The porous structure <NUM> may fill the gaps between the solid structure <NUM>. The porous structure <NUM> may extend from the upper surface <NUM> to the lower surface <NUM> or through a portion thereof. The porous structure <NUM> may also fill lateral windows <NUM> between the outer wall portion <NUM> and the inner wall portion <NUM>. Alternatively, the lateral windows <NUM> may remain empty. When present, the porous structure <NUM> within the lateral windows <NUM> may be in communication with the hollow interior chamber <NUM>. It is envisioned that alternative arrangements of solid and porous portions <NUM>, <NUM> may be utilized. Suitable solid and/or porous structures may include those identified in <CIT>, to which reference is made.

The porous structure <NUM> may have a randomized pattern of open pores or a repeating pattern of open pores. The porous structure <NUM> may have a suitable porosity (open volume). For example, the porous structure <NUM> may be greater than <NUM>% open, greater than <NUM>% open, greater than <NUM>% open, or approximately <NUM>% open, or approximately <NUM>% open. The porous structure <NUM> may feature interconnected pores or open pores. The porous structure <NUM> may have pores, for example, ranging from approximately <NUM> -<NUM>, approximately <NUM> -<NUM>, approximately <NUM>-<NUM>, or approximately <NUM>-<NUM> in diameter. The pore size may have an average pore size of about <NUM>-<NUM>, about <NUM>-<NUM>, or about <NUM>-<NUM>. The pore size distribution may be unimodal or bi-modal. Although spherical or partially-spherical pores or nodes are exemplified in forming the porous structure, it is envisioned that other suitable pore shapes and configurations may be used, for example, repeating or random patterns of cylinders, cubes, cones, pyramids, polyhedrons, or the like.

It is contemplated that different areas of the support structure <NUM> may have varying stiffness or strength, for example, variable A-P stiffness to achieve optimized load on an anterior graft or to achieve a desired level of flexibility within the implant <NUM>. Furthermore, the porous structure <NUM> may have different porosities or densities in different areas of the implant <NUM>. For example, the porous structure <NUM> may have a higher porosity or density along the inner perimeter compared to that at the outer perimeter, for example, with the inner area having a cancellous porosity and the outer area having a cortical porosity. The porous structure <NUM> may have various configurations, for example, a grid or honeycomb pattern which may promote bony in-growth. The surface texture of both the support structure and the porous structure may be controlled to provide both macro and micro texturizing. The features and characteristics described with respect to this embodiment may be incorporated in any of the embodiments described herein. Additionally, features described in any of the embodiments herein may be incorporated into any of the other embodiments.

With regard to the radiographic markers <NUM>, <NUM>, <NUM>, these may also be formed during the 3D printing process or may be added, for example, as inserts after manufacturing. When created during the 3D printing process, it may be desirable to use different porosities to highlight certain areas of the implant for radiographic or other imaging. For example, it may be desirable that the markers <NUM>, <NUM>, <NUM> are more radiolucent and other portions of the implant are generally more radioopaque. The visualization of the marker <NUM>, <NUM>, <NUM> may be achieved, for example, by selecting which regions are porous and/or the degree of porosity during the 3D printing process.

Claim 1:
An intervertebral implant (<NUM>) for implantation in an intervertebral space between vertebrae, the implant (<NUM>) comprising:
an implant body (<NUM>) extending from an upper surface (<NUM>) to a lower surface (<NUM>), the implant body (<NUM>) having a front end (<NUM>), a rear end (<NUM>) and a pair of spaced apart first and second side walls (<NUM>, <NUM>) extending between the front (<NUM>) and rear ends (<NUM>) such that an interior chamber (<NUM>) is defined within, wherein the rear end (<NUM>) includes an elongated opening (<NUM>) defining at least one track (<NUM>) and a dimple (<NUM>);
a pivoting member (<NUM>) including an enlarged head portion (<NUM>) and an elongated shaft portion (<NUM>) terminating at a distal end (<NUM>), wherein the distal end (<NUM>) is positioned within the dimple (<NUM>) and the enlarged head portion (<NUM>) is positioned within the at least one track (<NUM>); and
a blocking member (<NUM>) extending from the upper surface (<NUM>) to the lower surface (<NUM>) of the implant body (<NUM>) and securing the pivoting member (<NUM>) within the at least one track (<NUM>),
wherein the blocking member (<NUM>) extends through an opening (<NUM>) in at least one of the upper surface (<NUM>) and the lower surface (<NUM>),
wherein the pivoting member (<NUM>) is configured to slide along the at least one track (<NUM>) and articulate from an initial position to a final position and characterized in that in the final position the pivoting member (<NUM>) does not protrude past an outer footprint of the implant body (<NUM>).