DEVICE AND METHOD FOR CORRECTING SPINAL DEFORMITIES IN PATIENTS

Abstract

Devices and related methods for the dynamic correction of spinal deformities are disclosed. The devices and methods are particularly useful for correcting an abnormal curvature of the spine. In one exemplary embodiment, a method for correcting deformity via a spinal implant that can include a polymer between or attached to a top and bottom plate, which can exist in a wedge-shaped configuration in order to apply asymmetric forces to the spinal column, is provided. The implant may be inserted between adjacent vertebrae comprising part of the abnormal curvature, thereby restoring the normal curvature of a spine.

Claims

1. A spinal intervertebral disc implant device for alignment and/or realignment of a spinal column in more than one plane or axis comprising an elastic polymer component, wherein the spinal intervertebral disc implant device further comprises a top face and a bottom face, wherein a space between the top face and the bottom face is capable of being adjusted prior to or following insertion of the spinal intervertebral disc implant device, and wherein the spinal intervertebral disc implant device is capable of: (a) absorbing shock; (b) applying asymmetric force(s) to a vertebrae or vertebral element and adjacent vertebrae or vertebral element from within an intervertebral disc space by extension and/or contraction of one or more portions of the elastic polymer component; (c) aligning and/or realigning a spinal column; and (d) responding to loading and/or movement of the spinal column.

2. The spinal intervertebral disc implant device of claim 1, wherein the space between the top face and the bottom face is manually adjusted.

3. The spinal intervertebral disc implant device of claim 1, wherein the space between the top face and the bottom face is adjustable by internal gears and hinges that are capable of being manually adjustable by an external mechanism, tool, or force.

4. The spinal intervertebral disc implant device of claim 1, wherein the space between the top face and the bottom face is manually adjustable by expansion of a hinge in the device by an external mechanism, tool, or force.

5. The spinal intervertebral disc implant device of claim 1, wherein the asymmetric force(s) are provided by: a. polymeric and metallic materials combined to form one or more springs, solid bodies, or porous structures; or b. one or more metal springs, solid bodies, or porous structures.

6. A method of treating spinal deformity comprising implanting an elastic device capable of applying asymmetric forces to adjacent vertebrae to realign a vertebrae, vertebral element, and/or spinal column, wherein the asymmetric forces propagate through all or part of a spinal column in which the elastic device is implanted, wherein the elastic device comprises a rigid, multi-angled wedged device capable of applying the asymmetric forces by contacting the adjacent vertebral elements, and wherein the device comprises an elastic metallic material.

7. The spinal intervertebral disc implant device of claim 1, wherein the spinal intervertebral disc implant device is inserted using a tool that creates a temporary bond with the spinal intervertebral disc implant device.

8. The method of treating spinal deformity according to claim 6, wherein the elastic device is inserted using a tool that creates a temporary bond with the elastic device.

9. The spinal intervertebral disc implant device of claim 1, wherein the spinal intervertebral disc implant device is inserted via an anterior plane.

10. The spinal intervertebral disc implant device of claim 1, wherein the spinal intervertebral disc implant device is inserted via a lateral plane.

11. The spinal intervertebral disc implant device of claim 1, wherein the spinal intervertebral disc implant device is inserted via a posteriolateral plane.

12. The spinal intervertebral disc implant device of claim 1, wherein the spinal intervertebral disc implant device is inserted via a transforaminal plane.

13. The method of treating spinal deformity according to claim 6, wherein the elastic device is inserted via an anterior plane.

14. The method of treating spinal deformity according to claim 6, wherein the elastic device is inserted via a lateral plane.

15. The method of treating spinal deformity according to claim 6, wherein the elastic device is inserted via a posterolateral plane.

16. The method of treating spinal deformity according to claim 6, wherein the elastic device is inserted via a transforaminal plane.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0029] The accompanying drawings illustrate certain aspects of embodiments of the present invention and should not be used to limit the invention. Together with the written description the drawings serve to explain certain principles of the invention.

[0030] FIG. 1A depicts the spinal column in the coronal plane from the posterior view.

[0031] FIG. 1B depicts the lateral view of the spinal column in the sagittal plane.

[0032] FIG. 1C depicts an example case of spinal deformity in the coronal plane.

[0033] FIG. 1D depicts a vertebral segment from an isotropic view.

[0034] FIG. 1E depicts a vertebral segment from an anterior view.

[0035] FIG. 1F depicts a cross section of a typical vertebra.

[0036] FIG. 2A depicts an exemplary method for treatment of deformity using asymmetrical forces from a coronal view.

[0037] FIG. 2B depicts the correction achieved using various wedged angle constructs expanding upon this embodiment.

[0038] FIG. 2C depicts optimization of the corrective force.

[0039] FIG. 3A depicts an exemplary embodiment of the device from an isotropic view.

[0040] FIG. 3B depicts an exemplary embodiment from a side view.

[0041] FIG. 3C depicts an exemplary embodiment from a side view where the polymer is preoperatively wedged.

[0042] FIG. 3D depicts a cross sectional view of an exemplary embodiment.

[0043] FIG. 3E depicts a cross sectional view from a vertical viewing plane of an exemplary embodiment in which there exists an internal elastic region, and a cross sectional view of an exemplary embodiment from a horizontal viewing plane.

[0044] FIG. 3F depicts an example of an insertion of said embodiment into the vertebral column.

[0045] FIG. 4A depicts a cross sectional view of an exemplary embodiment where there exist multiple polymer sections.

[0046] FIG. 5A depicts a cross sectional view of an exemplary embodiment where there exist multiple discrete spring sections.

[0047] FIG. 5B depicts a side view of an exemplary embodiment where there exist multiple metal spring sections.

[0048] FIG. 6A-C depicts differing frictional surfaces taught herein.

[0049] FIG. 7A depicts a combination with screw implantation from a side view.

[0050] FIG. 7B depicts a combination with screw implantation from an anterior view.

[0051] FIG. 8A depicts an embodiment where multiple device sections are inserted and may join from a top view.

[0052] FIG. 8B depicts a possible insertion of the multiple device sections.

[0053] FIG. 8C depict a possible connection mechanism of the multiple device sections.

[0054] FIG. 9A depicts the hinge-mechanism embodiment from a top view.

[0055] FIG. 9B depicts the hinge-mechanism embodiment from a side view.

[0056] FIG. 9C depicts the hinge-mechanism embodiment from a top view within the vertebral space.

[0057] FIG. 10A depicts the multiple device hinge-mechanism embodiment from a top view.

[0058] FIG. 10B depicts the multiple device hinge-mechanism embodiment from a top view within the vertebral space.

DETAILED DESCRIPTION OF VARIOUS EMBODIMENTS OF THE INVENTION

[0059] Various embodiments will now be described in detail to provide an understanding of the structure, function, manufacture, and use of the devices and methods disclosed herein. It should be understood that the following discussion of exemplary embodiments is not intended as a limitation on the invention; rather, the following discussion is provided to give the reader a more detailed understanding of certain aspects and features of the invention.

[0060] One or more examples of the embodiments are illustrated in the accompanying drawings. Those skilled in the art will understand that the devices and methods specifically described herein and illustrated in the accompanying drawings are non-limiting exemplary embodiments and that the scope of the present invention is defined solely by the claims. It will be to those that various modifications and variations can be made in the practice of the present invention without departing from the scope or spirit of the invention; the features illustrated or described in connection with one exemplary embodiment may be combined with the features of other embodiments. Such modifications and variations are intended to be included within the scope of the present invention. All references cited in this application are hereby incorporated by reference in their entireties.

[0061] The current invention describes methods and devices for correcting spinal deformities, and in particular, correcting abnormal curvature including most cases of spinal deformity. In embodiments, one or more dynamic implants which exist in a wedge-shaped configuration or exert asymmetrical force to correct wedging are provided. In an exemplary embodiment, one or more implants can be positioned between adjacent vertebra at the apex of curvature to increase the height of the disc space on the concave side and decrease that on the convex side by dynamically applying continuous forces to the endplates of the adjacent vertebrae over time.

[0062] Normal spinal orientation is depicted in FIG. 1A-B. In FIG. 1A, the spine is viewed posteriorly as it exists in the coronal plane (20) and in FIG. 1B, the spine is viewed laterally as it exists in the sagittal plane (22). The spine consists of 7 cervical vertebrae (10), 12 thoracic vertebrae (12), 5 lumbar vertebrae (14), the sacrum (16), and the coccyx (18). Spinal deformity typically occurs in some region between the thoracic and lumbar vertebrae. An example of spinal deformity, scoliosis, is shown in FIG. 1C in a posterior view as would be seen in the coronal plane (24) with the apex of curvature located in the thoracic region (26). In FIG. 1D-E, a single vertebral segment is shown; the vertebral segment comprises a top and bottom vertebra as well as the disc in between and the muscles and ligaments attached to the top and bottom vertebrae. In an embodiment, the current invention acts directly on the vertebrae of a single vertebral segment, through which forces may propagate to act on adjacent vertebral segments. A cross sectional view of this vertebral segment is shown in FIG. 1F.

[0063] In one embodiment, the current invention comprises a method by which an expansive force is applied to one or more concave aspects of the vertebral segment. A tensile force may also be applied to one or more convex aspects of the vertebral segment. Such forces increase disc space height in concave aspects of the vertebral segment and decrease disc height in convex aspects of the vertebral segment. As shown in FIG. 2A, the forces may result in the realignment of the vertebral segment, which may lead to a propagation of forces through the spinal column, realigning other aspects of the column. In this method, a part of the disc or the whole disc would be removed so as to insert an implant (2100) which could apply such forces. FIG. 2B depicts correction achieved using various wedged angle constructs expanding upon this embodiment. FIG. 2C presents data from a pilot study of force optimization in applying a corrective force to the spinal column from within the disc space. Optimal correction curve was found to be within the range of 80 to 160 N, with maximum correction occurring at 120 N. Force above this range caused over correction, and those below caused undercorrection. Thus, the current method would involve the application of forces as described above and herein within a similarly optimized range.

[0064] In aspects, the implant, which may engage in such a method of correction of deformity, may have various properties. One exemplary embodiment is shown in FIG. 3A-D, in which the device has a top plate (3200) and bottom plate (3300) with an elastic section in the middle (3400); this section may be an elastic polymer. Such internal section, in a preferred aspect, is what applies the forces to the adjacent vertebra above and below the device. As shown in FIG. 3D, the cross-sectional area, in aspects, is of the same, similar, or approximate footprint, shape, or form as that of the vertebrae, so that it completely or partially matches the vertebral segment. The elastic section may have an internal region (3500) which is less stiff and matches the elastic properties of the disc (e.g., FIG. 3E) to act as a shock absorber. The insertion of such device (3100) into the disc space is shown in FIG. 3F; the device, in aspects, uses resultant forces to the wedging of the vertebrae that pushed the concave aspects apart. According to data from a pilot study of force optimization for such an elastic region in correcting a scoliotic curve, a factor of 200 was added to the force to account for the normal axial loading of the spine. This value was derived based on research carried out by Izamburt et al., in which IVDs were preloaded with 400 N of force to mimic axial loading of an adult spine. This value was halved to account for the lighter weight of the targeted pediatric patient population. Required Young's modulus was determined to be 8.67 MPa. The elastic modulus in a preferred embodiment of the current invention resembles that of the natural intervertebral disc, which lies within 5.8-42.7 MPa. This, however, may be a result of the small Cobb angle generated by current simulations. The required elastic modulus for this material may be calculated in a similar manner to determine material characteristics of such an embodiment, and/or other embodiments presented herein.

[0065] In one embodiment, the device may comprise multiple polymer sections (4600) in various shapes depending on what force(s) are desired to be applied and where on the endplates of the adjacent vertebrae the force(s) must or should be applied (see, e.g., FIG. 4A). Such a device may have shorter elements that pull one or more aspects of the vertebrae together through a tensile force or longer elements that push aspects of the vertebrae apart, by way of example. Instead of polymer springs, the device may include discrete springs (5700) (see, e.g., FIG. 5A-B).

[0066] In order for the device to remain within the disc space, it is preferable, in embodiments, to have as much of a contact with the adjacent vertebrae as possible to create a frictional interface between the plates of the device and the endplates of the adjacent vertebrae. A variety of interfaces can increase the surface area including ridges (see, e.g., FIG. 6A), spikes (see, e.g., FIG. 6B), bumps (see, e.g., FIG. 6C), or other similar protrusions.

[0067] In order to apply a compressive force, it may be necessary to attach the implant (7100) to the adjacent vertebrae via a screw, attachment, or similar, system (7800) (see, e.g., FIG. 7A-B). In embodiments, one or more screws or other attachment mechanisms may be inserted through a protrusion of one or both or more plates of the implant or through the one or both or more of the plates of the device itself.

[0068] The device may comprise a configuration in which it is divided into two or more parts that make separate implants (8101 and 8102), or two or more parts of the same implant. which can be inserted from two or more sides of the disc space (see, e.g., FIG. 8A-B). The device may exist as two or more separate implants (or parts of the same implant) within the space, or may be connected via one or more connecting mechanisms including, but not limited to, hooks or screws, by way of example only. (See, e.g., FIG. 8C).

[0069] Another possible embodiment of the device may require a smaller incision to access the disc space. As shown in, for example, FIG. 9A-B, the device (9100) may, in aspects, have two or more elements with top and bottom plates with an elastic section in between that are connected via a hinge mechanism (9900). The implant is inserted through an incision and once placed in the disc space, the forward element of the device is rotated about the hinge so that it lies parallel to the back element (see, e.g., FIG. 9C).

[0070] Such hinged elements may be scaled to a larger size so the one or more devices can be inserted into the disc space with one or more different polymer properties between the top and bottom plates. Such devices are depicted in FIG. 10A-B. The devices can be inserted in various orientations into the space as shown in FIG. 10B, particularly.

[0071] One skilled in the art will recognize that the disclosed features may be used singularly, in any combination, or omitted based on the requirements and specifications of a given application or design. When an embodiment refers to “comprising” certain features, it is to be understood that the embodiments can alternatively “consist of” or “consist essentially of” any one or more of the features. Other embodiments of the invention will be apparent to those skilled in the art from consideration of the specification and practice of the invention.

[0072] A “vertebral element” includes a vertebrae, a vertebrae disc, a vertebrae above and below a disc, a space between vertebrae, a space in vertebrae, a vertebrae endplate, and/or a portion of a spinal column, alone or together in any combination.

[0073] It is noted in particular that where a range of values is provided in this specification, each value between the upper and lower limits of that range is also specifically disclosed. The upper and lower limits of these smaller ranges may independently be included or excluded in the range as well. The singular forms “a,” “an,” and “the” include plural referents unless the context clearly dictates otherwise. It is intended that the specification and examples be considered as exemplary in nature and that variations that do not depart from the essence of the invention fall within the scope of the invention. Further, all of the references cited in this disclosure are each individually incorporated by reference herein in their entireties and as such are intended to provide an efficient way of supplementing the enabling disclosure of this invention as well as provide background detailing the level of ordinary skill in the art.