Patent Description:
Back problems are one of the most common and debilitating occurrences in people of all ethnicities. In the United States alone, over <NUM>,<NUM> spine lumbar and cervical fusion procedures are performed each year. One of the causes of back pain and disability results from the rupture or degeneration of one or more intervertebral discs in the spine. Surgical procedures are commonly performed to correct problems with displaced, damaged, or degenerated intervertebral discs due to trauma, disease, or aging. Generally, spinal fusion procedures involve removing some or the all of the diseased or damaged disc, and inserting one or more intervertebral implants into the resulting disc space. Anterior lumbar interbody fusion (ALIF) and lateral lumbar interbody fusion procedures are two of the techniques that spine surgeons use to access the portions of the spine to be repaired or replaced. Replacement of injured or deteriorated spinal bone with artificial implants requires a balance of knowledge of the mechanisms of the stresses inherent in the spine, as well as the biological properties of the body in response to the devices. Further, the size, configuration, and placement of an artificial implant requires precision positioning and handling by a skilled surgeon.

<CIT> describes an expandable interbody implant for insertion into a disc space between two adjacent vertebrae. In the implant, first and second plates are joined by a hinge and a linkage is disposed between the plates. A translation mechanism moves the linkage between collapse and expanded positions to move the plates away from one another.

The present subject disclosure provides a novel implant device which may be adjusted to form a particular lordosis angle depending on the needs or the functionality of the particular placement of the implant.

In particular, the present invention provides an implant device as set out in claim <NUM>. Further advantageous features are set out in the dependent claims.

Many advantages of the present subject disclosure will be apparent to those skilled in the art with a reading of this specification in conjunction with the attached drawings. The implants described with respect to <FIG>, <FIG> and <FIG> are included for background information and context. An embodiment of the present disclosure is illustrated in <FIG>, <FIG> and <FIG>. In the drawings:.

The following detailed description references specific embodiments of the subject disclosure and accompanying figures, including the respective best modes for carrying out each embodiment. It shall be understood that these illustrations are by way of example and not by way of limitation.

Illustrative embodiments of the invention are described below. In the interest of clarity, not all features of an actual implementation are described in this specification. It will of course be appreciated that in the development of any such actual embodiment, numerous implementation-specific decisions must be made to achieve the developers' specific goals, such as compliance with system-related and business-related constraints, which will vary from one implementation to another. Moreover, it will be appreciated that such a development effort might be complex and time-consuming, but would nevertheless be a routine undertaking for those of ordinary skill in the art having the benefit of this disclosure.

While the subject matter is susceptible to various modifications and alternative forms, specific embodiments thereof have been shown by way of example in the drawings and are herein described in detail. It should be understood, however, that the description herein of specific embodiments is not intended to limit the subject matter to the particular forms disclosed, but on the contrary, the subject matter is to cover all modifications, equivalents, and alternatives falling within the scope of the claims as defined hereafter.

The subject disclosure relates to an expandable lordosis intervertebral implant. The implant has a collapsed configuration and an expanded configuration, and is designed to be placed into an intervertebral disc space in its collapsed configuration and then expanded while in the disc space to its expanded configuration. When the implant is in its expanded configuration, it creates a lordotic angle in the disc space (i.e., the anterior height of the implant is greater than the posterior height of the implant). The implants as shown and described herein are dimensioned for use in a direct lateral approach to the spine, however, it is contemplated that a similar implant with a similar expansion mechanism could be used in an anterior approach to the spine.

As shown in <FIG>, the first example of an implant <NUM> comprises a top plate <NUM>, a bottom plate <NUM>, linkages <NUM> connecting the top and bottom plates <NUM>, <NUM>, a drive shaft <NUM> (see <FIG>) coupled to the linkages <NUM> and a threaded coupling <NUM> between the bottom plate <NUM> and the drive shaft <NUM>.

The top plate <NUM> has an upper bone contacting surface <NUM> and an opposite interior surface <NUM> (see <FIG>). As shown in the example, the top plate <NUM> includes one or more fusion apertures <NUM> extending through the bone contacting surface <NUM> and interior surface <NUM>. The interior surface <NUM> includes recesses <NUM> to accommodate the linkages <NUM> in the interior of the implant <NUM>. The recesses <NUM> further comprise a pocket <NUM> that houses the superior ends <NUM> of the linkages <NUM>. As shown in <FIG>, the superior ends <NUM> of the linkages <NUM> are coupled to the interior surface <NUM> of the top plate <NUM> via a pivot pin <NUM>.

The bottom plate <NUM> has a lower bone contacting surface <NUM> and an opposite interior surface <NUM>. The bottom plate <NUM> includes one or more fusion apertures <NUM> extending through the lower bone contacting surface <NUM> and the opposite interior surface <NUM>. The distal wall <NUM> of the lower plate <NUM> includes a threaded hole for receiving the threaded coupling <NUM>. The anterior wall <NUM> of the bottom plate <NUM> includes pin slots (not shown) configured to receive pins that couple the inferior end of the linkages <NUM> to the bottom plate <NUM>. The proximal end <NUM> of the bottom plate <NUM> includes a recess <NUM> configured to receive a detachable fixation tab <NUM>. The recess <NUM> has a shape that complements the shape of the attachment portion <NUM> of the detachable fixation tab <NUM>. As shown in the example, the recess <NUM> and the attachment portion <NUM> of the detachable tab <NUM> are generally flower shaped to allow the tab <NUM> to be attached in a variety of positions, however, other shapes may be implemented.

The interior surface <NUM> of the bottom plate <NUM> houses the drive shaft <NUM>. As illustrated in the example in <FIG>, the interior surface <NUM> of the bottom plate <NUM> includes a track dimensioned to receive the drive shaft <NUM>. As shown best in <FIG> and <FIG>, the distal end <NUM> of the drive shaft <NUM> includes a hole for receiving the threaded coupling <NUM>. The drive shaft <NUM> further includes pin holes <NUM> dimensioned to receive the pin <NUM> that couples the inferior end <NUM> of the linkages <NUM> to the bottom plate <NUM>. One end of the pin <NUM> resides and translates within the slots <NUM> in the anterior wall <NUM> of the bottom plate <NUM>, the center of the pin <NUM> is received in a pin hole through the inferior end <NUM> of the linkages <NUM> and a second end of the pin <NUM> is received in the pin hole <NUM> in the drive shaft <NUM>.

The drive shaft <NUM> is configured such that when the implant <NUM> is in its collapsed configuration, the distal surface <NUM> of the drive shaft <NUM> is in close proximity to the proximal face <NUM> of the distal wall <NUM> of the bottom plate <NUM>. As the threaded coupling <NUM> is rotated in a first direction, the drive shaft <NUM> translates in a proximal direction. Translation of the drive shaft <NUM> in the proximal direction causes the pins <NUM> received through the inferior ends <NUM> of the linkages <NUM> to slide proximally within the pin slots <NUM> in the bottom plate <NUM> while causing the linkages <NUM> to pivot about the pivot pin <NUM> coupled to the top plate <NUM>. The pivoting of the linkages <NUM> about the pivot pin <NUM> allows the linkages <NUM> to move from a first, generally horizontal position in the interior of the implant <NUM> to a second, more vertical position, pushing the top plate <NUM> upwards and thereby causing a change in the anterior height of the implant <NUM> when the implant is in its expanded state. The top plate <NUM> is coupled to the bottom plate <NUM> via a hinge <NUM> on the posterior side <NUM> of the implant <NUM>. The described expansion mechanism allows the lordotic angle of the implant <NUM> to be increased in non-discrete increments, meaning the surgeon can increase the angle of lordosis until the desired amount of lordosis is reached.

Once the implant <NUM> has been expanded to the desired level of lordosis, the implant <NUM> can be packed with bone graft or bone graft substitute through the same hole <NUM> through which instruments used to actuate the drive mechanism are inserted. Upon packing the implant <NUM> with bone graft or bone graft substitute, the fixation tab <NUM> is coupled to the proximal end <NUM> of the implant <NUM>. As shown in the example, the fixation tab <NUM> includes a superior and an inferior extension <NUM>, <NUM> with a screw hole <NUM> therethough. The superior extension <NUM> is configured to be positioned adjacent the superior vertebral body and the inferior extension <NUM> is configured to be positioned adjacent the inferior vertebral body. A fixation tab <NUM> with a single extension for receiving a single screw therethrough and positioned adjacent only one of the superior and inferior vertebral body is also contemplated. It is also contemplated that the extensions include an anti-backout element for preventing backout of the screws after they've been placed through the extension and into the vertebral body. Further details of an exemplary fixation tab <NUM> are shown in <FIG>.

According to the example shown in <FIG>, a method (not claimed) of using the implant <NUM> is as follows: a disc space is accessed via a lateral approach; the disc space is prepared to receive an intervertebral implant; the implant <NUM> is inserted into the prepared disc space in its collapsed position having <NUM> degrees of lordosis; an expansion tool is used to rotate the threaded coupling <NUM>, thereby causing the drive shaft <NUM> to translate in a proximal direction; the implant <NUM> is expanded until the desired degree of lordosis is achieved; the expansion tool is withdrawn from the implant <NUM>; bone graft or bone graft substitute is packed into the interior of the implant <NUM>; a fixation tab <NUM> is attached to the proximal end <NUM> of the implant <NUM> and at least one screw is inserted through the fixation tab <NUM> into the vertebral body.

<FIG> illustrate an alternative embodiment of the expandable lordosis intervertebral implant. The implant according to this embodiment shares many of the same features as the implant of <FIG>. The same features and elements will not be re-described in this embodiment but may be labeled using a "<NUM>" instead of a "<NUM>" as the first digit of the three digit label. The reader should understand that the features are the same or similar as in the first embodiment. Attention will be directed to the distinctions between this embodiment and the embodiment presented in <FIG>. One of the differences according to this alternative embodiment is that the top plate <NUM> and the bottom plate <NUM> include planar extensions <NUM>, <NUM> that together define an anterior wall when the implant <NUM> is in its expanded state. These planar extensions <NUM>, <NUM> are configured to enclose the generally hollow interior of the implant <NUM>.

The expansion mechanism of the device <NUM> according to the alternative embodiment of <FIG> include a chassis <NUM> with a threaded interior. The drive screw <NUM> resides within the chassis <NUM> and has threads that engage the threaded interior of the chassis <NUM>. Turning the drive screw causes the chassis <NUM> to translate proximally, consequently causing pins <NUM> coupled to the chassis <NUM> to translate proximally within slots <NUM> in the bottom anterior wall <NUM> of the bottom plate <NUM>. Linkages <NUM> are coupled to these pins <NUM> at their inferior end and coupled to the top plate <NUM>, such that when the chassis <NUM> translates proximally, the inferior ends of the linkages <NUM> are moved proximally, causing the linkages <NUM> to move to a more upright position and thereby causing the top plate <NUM> to move upward and away from the bottom plate <NUM>, increasing the height and lordotic angle of the implant. This motion may be viewed in the figures as <FIG> show the implant <NUM> in a low profile, closed/collapsed configuration. <FIG> shows the position of the various components with the top plate <NUM> removed for a better depiction of the mechanism, with pins <NUM> in a distal most position within their respective slots <NUM>. <FIG> show the implant <NUM> in an open, , expanded, lordotic angle configuration. <FIG> shows the position of the various components with the top plate <NUM> removed for a better depiction of the mechanism, with pins <NUM> having been translated proximally within slots <NUM>, thereby pushing linkages <NUM> in a vertical manner, which results in the lifting of the top plate <NUM>. <FIG> show the implant <NUM> from a lower perspective view (<FIG>) and a side view (<FIG>) in an open, expanded position with pins <NUM> having been translated proximally within slots <NUM>, thereby pushing linkages <NUM> in a vertical manner, which results in the lifting of the top plate <NUM>.

The alternative embodiment presented in <FIG> presents alternative additional features not shown in <FIG>. The top plate <NUM> has an additional top anterior cover <NUM> and the bottom plate <NUM> has an additional bottom anterior cover <NUM> which together serve to cover the entire anterior portion of the implant <NUM> when in a collapsed or expanded implant configuration. Further, top anterior cover <NUM> is lifted along with the top plate <NUM> when the pins <NUM> are slid proximally within the pin slots <NUM>. Anti-migration features <NUM> on the exterior portions of both the top plate <NUM> and the bottom plate <NUM> serve to provide further frictional and contact surface between the implant <NUM> and the adjoining vertebrae.

Though not shown, it is contemplated that the second embodiment presented in <FIG> would also have an attachment feature for receiving a fixation tab <NUM> as previously described in the first embodiment presented in <FIG>. The method of use (not claimed) of the second embodiment would also be the same as the method of use described for the first embodiment.

<FIG> illustrate an embodiment of the expandable lordosis intervertebral implant. The implant according to this embodiment shares many of the same features as the example of <FIG>, and the example of <FIG>. The same features will not be re-described in this embodiment but may be labeled using a "<NUM>" instead of a "<NUM>" or "<NUM>" as the first digit of the three digit label. The reader should understand that the features are the same or similar as in the first and second embodiments. Attention will be directed to the distinctions between this embodiment and the prior described embodiments. Similar to the embodiment shown and described in <FIG>, the present embodiment also has a top plate <NUM> and a bottom plate <NUM> which include planar extensions <NUM>, <NUM> that together define an anterior wall when the implant <NUM> is in its expanded state. These extensions <NUM>, <NUM> are configured to enclose the generally hollow interior of the implant <NUM>. An additional feature is a number of projections <NUM> on both the top plate <NUM> external surface and bottom plate <NUM> external surface. These fang-like projections <NUM> work in conjunction with the anti-migration features <NUM> on the top plate <NUM> and bottom plate <NUM> surfaces to create a friction fit with adjoining vertebrae.

The top plate <NUM> has a top anterior wall <NUM> with a further side wall <NUM> located at the distal end <NUM> of the implant <NUM>, away from the insertion port <NUM> located at the proximal end <NUM> of the implant <NUM>. This contra-lateral and anterior design has an opening and closing mechanism similar to that described in <FIG> and akin to standard garage doors. Additional apertures <NUM> may be used in conjunction with insertion port <NUM> as receiving apertures for an oblong inserter tool (not shown). Pin <NUM> is used to connect the top plate <NUM> with the bottom plate <NUM>, and serves as an axis of rotation of one plate with respect to the other.

<FIG> show a chassis <NUM> and its relative positioning within the bottom plate <NUM>. A set of primary linkages <NUM> having spherical end portions <NUM> are connected to a set of support linkages <NUM>, which are connected to the body portion <NUM> of the chassis <NUM> via pins <NUM>. The pins <NUM> serve as the axis of rotation of the support linkages <NUM>, which in turn allow for rotation of the primary linkages <NUM> via pins <NUM>. The primary linkages <NUM> are not directly connected to the chassis body <NUM>. Thus, the primary linkages <NUM> only articulate about a rotational axis formed by pins <NUM>, and do not translate. The support linkages <NUM> both articulate and translate.

Chassis <NUM> includes oval protrusions <NUM> which are aligned with channels <NUM> and used to "drop down" the chassis <NUM> within the internal frame of the bottom plate <NUM> and then shift the chassis <NUM> back distally to lock the chassis <NUM> within the frame of the bottom plate <NUM>. This mechanism secures the position of the chassis <NUM> with respect to the bottom plate <NUM>.

Screw <NUM> in conjunction with washer <NUM> act to lock the expansion/collapsing mechanism within chassis <NUM>. As shown in <FIG>, the screw <NUM> with washer <NUM> are locked into position by a friction fit within an accommodating portion <NUM> of the bottom plate <NUM>. Additionally, raptor spring <NUM> has a protrusion <NUM> which provides further a locking mechanism for the screw <NUM> to position it within place. The protrusion <NUM> mates with divots <NUM> positioned annularly to form an annular flower pattern. A divot is available every <NUM>-<NUM> degrees such that a ratcheting mechanism is available for the surgeon to determine the precise level of openness of the top plate <NUM> is desired. Once such a lordosis angle is determined, the protrusion <NUM> of the spring <NUM> is allowed to mate with divot <NUM> of the bottom plate <NUM>, to essentially lock the position and prevent further movement. Some level of force is required to further open or close the top plate <NUM>.

Top plate <NUM> is opened up by the mechanism driven by the chassis <NUM> such that the spherical heads <NUM> of the primary linkages <NUM> push the top plate <NUM> upward by physical upward force. This is essentially the expansion mechanism. Contraction or collapsing of the implant <NUM> involves a different mechanism which is also positioned on the chassis <NUM>. As shown in <FIG>, a diagonally cut groove <NUM> in the body of the chassis <NUM> allows for the diagonal translation of a protrusion <NUM> in the chassis <NUM>, which is connected to the top plate <NUM> through connection <NUM>. The contracted implant <NUM> has the protrusion <NUM> in its lowermost position on a distal end of the groove <NUM>. This serves to maintain a relatively tight connection and parallel configuration between the top plate <NUM> and the bottom plate <NUM>. As the expansion mechanism is activated, the protrusion is extended proximally such that it begins to lift up diagonally in the groove <NUM>, thereby lifting the top plate <NUM>. However, if there is desire to contract the implant <NUM>, the protrusion <NUM> travels back down the groove <NUM>, serving to lower the connection <NUM> between the top <NUM> and bottom <NUM> plates, and therefore the top plate <NUM> is lowered down toward the bottom plate <NUM> again. During the expansion process, this sliding protrusion mechanism is passive, and during the contraction mechanism, this sliding protrusion mechanism becomes active to pull down the top plate <NUM>.

Various fixation devices with locking and anti-backout mechanisms may be used with the implants <NUM>, <NUM>, and <NUM> shown in the present disclosure. One such type is shown in <FIG>. In this particular embodiment shown, fixation device <NUM> with anti-backout device has a top circular portion <NUM> and bottom circular portion <NUM> having an aperture <NUM> therein. The middle portion <NUM> is the engagement mechanism which services to lock into an accommodating portion of an implant, such as those shown in <FIG>. The device shown contains a canted coil mechanism <NUM> as its anti-backout mechanism, but other types may also be used to secure the implant position with respect to adjacent vertebra once it is placed and sized.

Claim 1:
An implant device (<NUM>), comprising:
a top plate (<NUM>) coupled to a bottom plate (<NUM>) by a hinge (<NUM>), wherein the top plate (<NUM>) comprises an extended anterior wall (<NUM>) and the bottom plate (<NUM>) comprises an extended anterior wall (<NUM>);
a linkage (<NUM>, <NUM>) disposed between the top (<NUM>) and bottom (<NUM>) plates;
a moveable chassis (<NUM>) positioned within the bottom plate (<NUM>);
a screw (<NUM>) positioned within and engaged with the moveable chassis (<NUM>); and
a washer (<NUM>) disposed about the screw (<NUM>),
wherein rotation of the screw (<NUM>) is configured to cause incremental ratchet movement of the chassis (<NUM>), and to cause the linkage (<NUM>, <NUM>) to move from a collapsed position in which the extended anterior wall (<NUM>) of the top plate (<NUM>) and the extended anterior wall (<NUM>) of the bottom plate (<NUM>) are substantially parallel with each other, to an expanded position in which the top plate (<NUM>) is pushed away from the bottom plate (<NUM>), such that the top plate (<NUM>) and the bottom plate (<NUM>) form an angle with respect to each other.