Ring-axis artificial joint

Abstract

The present invention includes an artificial device for supporting the atlantoaxial joint between the C1 vertebra and the C2 vertebra after an odontectomy procedure. The device includes an artificial odontoid replacement that can be fixed to the C2 vertebra by at least two screws. The device also includes a bracket that replaces the anterior arch of the C1 vertebra. The bracket is fixed to the lateral mass of the C1 vertebra by at least two screws. Further, the bracket is engageable with the odontoid replacement fixed to the C2 vertebra when fixed to the C1 vertebra.

Description

Technical Field

[0001]

[0001] This application claims priority to U.S. Provisional Application No. 63 / 359,340, filed on July 8, 2022, the disclosure of which is hereby incorporated by reference in its entirety.

[0002]

[0002] The present invention relates to methods and devices for treating occipitocervical and atlantoaxial fixation. More specifically, the present invention relates to an endoscopic transnasal surgical approach for implanting an atlantoaxial artificial joint.

Background Art

[0003]

[0003] Surgical techniques for occipitocervical and atlantoaxial fixation are used to treat instability involving the occipitocervical (O-C1) and atlantoaxial (C1-2) joints following odontoidectomy. However, this often requires a separate incision to perform fusion and fixation via a posterior approach, resulting in a loss of mobility, particularly external rotation of the head. Implantation of an atlantoaxial artificial device may help reduce ventral brainstem compression while maintaining movement and reducing the time spent under anesthesia. It would be advantageous to implant such a device through a transnasal passage. To date, however, there is no validated method for implanting an atlantoaxial artificial device in such a manner.

Summary of the Invention

[0004]

[0004] The present invention is a novel transnasal method for implanting an atlantoaxial joint prosthesis. One embodiment of the present invention is a system that enables a procedure for occipitocervical and atlantoaxial fixation. This new method provides a minimally invasive advancement in the surgeon's ability to maintain the movement of the atlantoaxial joint after odontectomy. In one embodiment, the present invention includes an artificial device for supporting the atlantoaxial joint between the C1 vertebra and the C2 vertebra after an odontectomy procedure that results in a C1 vertebra without an anterior arch and a C2 vertebra without an odontoid process. The device includes an artificial odontoid replacement that can be fixed to the C2 vertebra by at least two screws. The device also includes a bracket for replacing the anterior arch of the C1 vertebra. The bracket can be fixed to the lateral mass of the C1 vertebra by at least two screws. Further, when fixed to the C1 vertebra, the bracket can engage the odontoid replacement fixed to the C2 vertebra.

[0005]

[0005] In one embodiment, the artificial odontoid replacement can be fixed to the C2 vertebra by at least two cantilever screws. In another embodiment, the artificial odontoid replacement contains titanium. In one embodiment, the bracket contains titanium. In another embodiment, the artificial odontoid replacement and the bracket contain an antibiotic coating.

[0006]

[0006] In another aspect of the present invention, a method for implanting an artificial odontoid into the C2 vertebra is provided. The method includes performing an endoscopic transnasal odontectomy procedure in which the anterior arch of the patient is removed from the patient's C1 vertebra and the odontoid process of the patient is removed from the patient's C2 vertebra. Thereafter, the artificial odontoid replacement is inserted through the patient's transnasal passage. The artificial odontoid replacement is positioned and fixed to the patient's C2 vertebra at the location where the odontoid process previously existed. Thereafter, the bracket is inserted through the patient's transnasal passage. The bracket is positioned and fixed to the patient's C1 vertebra at the location where the anterior arch of C1 previously existed. Finally, the bracket is engaged with the artificial odontoid replacement.

[0007]

[0007] In one embodiment, the odontoidectomy procedure includes first exposing the patient's O-C1 joint through the nasal passage using an inferior U-shaped nasopharyngeal flap. Thereafter, the anterior arch of the patient's C1 vertebra is removed and the odontoid process of the patient's C2 vertebra is removed.

[0008]

[0008] In another embodiment, the odontoid replacement is fixed to the C2 vertebra by at least two cantilever screws. In one embodiment, the bracket is fixed to the C1 vertebra by at least two cantilever screws. In another embodiment, the bracket is fixed to the C1 vertebra using neuronavigation guidance. In one embodiment, the artificial odontoid replacement comprises titanium. In another embodiment, the bracket comprises titanium. In one embodiment, the artificial odontoid replacement and the bracket comprise an antibiotic coating.

[0009]

[0009] This specification concludes with claims that particularly point out and distinctly claim the technology, but it is believed that the technology will be better understood from the following description of specific embodiments read in conjunction with the accompanying drawings in which like reference numerals identify the same elements.

Brief Description of the Drawings

[0010]

Figure 1A

[0010] A perspective view of one embodiment of the anterior arch bracket and odontoid replacement of the present invention.

Figure 1B

[0011] A perspective view of one embodiment of the anterior arch bracket of the present invention.

Figure 1C

[0012] A perspective view of one embodiment of the odontoid replacement of the present invention.

Figure 2

[0013] An image showing occipitocervical fixation.

Figure 3A

[0014] An enlarged image of C1-C2 before segmentation.

Figure 3B

[0015] An enlarged image of C1-C2 after segmentation.

Figure 4

[0016] It is an image showing the front view of C1.

Figure 5

[0017] It is an image showing the top view of C1.

Figure 6

[0018] It is a perspective view of C2, showing the dimension lines for the odontoid process.

Figure 7A

[0019] It is a perspective view of the first embodiment of the anterior arch bracket of the present invention.

Figure 7B

[0020] It is a perspective view of the second embodiment of the anterior arch bracket of the present invention.

Figure 8A

[0021] It is a perspective view of the first embodiment of the tooth projection replacement of the present invention.

Figure 8B

[0022] It is a perspective view of the second embodiment of the tooth projection replacement of the present invention.

Figure 8C

[0023] It is a perspective view of the third embodiment of the tooth projection replacement of the present invention.

Figure 8D

[0024] It is a perspective view of the fourth embodiment of the tooth projection replacement of the present invention.

Figure 9

[0025] It is an image of the bracket according to the present invention attached to C1.

Figure 10

[0026] It is an image of the tooth projection replacement according to the present invention attached to C2 after odontectomy.

Modes for Carrying Out the Invention

[0011]

[0027] Details of one or more embodiments of the disclosed subject matter are described herein. Modifications of the embodiments described herein and other embodiments will be apparent to those skilled in the art after investigation of the information provided herein.

[0012]

[0028] This disclosure may be more readily understood by reference to the following detailed description of embodiments, which is to be read in conjunction with the figures of the accompanying drawings that form a part of this disclosure. It is to be understood that this application is not limited to the specific devices, methods, conditions, or parameters described and / or shown herein, and that the terminology used herein is for the purpose of describing particular embodiments by way of example only and is not intended to be limiting. Similarly, in some embodiments, as used herein including the appended claims, the singular forms "a", "an", and "the" include the plural, and references to a particular numerical value include at least that particular value unless the context clearly dictates otherwise. Ranges may be expressed herein as from "about" or "approximately" one particular value and / or to "about" or "approximately" another particular value. When such a range is expressed, another embodiment includes from one particular value and / or to another particular value. Similarly, when values are expressed as approximations by use of the antecedent "about", it will be understood that the particular value forms another embodiment.

[0013]

[0029] The following terms are thought to be well understood by one of ordinary skill in the art, but definitions are set forth to facilitate explanation of the disclosed subject matter. Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which the disclosed subject matter belongs.

[0014]

[0030] Certain terms are used merely for convenience in the following description and are not limiting. The words "right," "left," "lower," and "upper" designate directions within the drawings to which reference is made. The words "inwardly" or "proximally" and "outwardly" or "distally" refer respectively to directions toward and away from the geometric center of the implant and its associated parts. The words "anterior," "posterior," "superior," "inferior," and related words and / or phrases designate, without limitation, preferred positions and orientations in the human body to which reference is made. The terms include the words listed above, derivatives thereof, and words of similar meaning.

[0015]

[0031] Like reference numerals will be used throughout the application to describe like or identical components of the preferred embodiments of the implant described herein, and the description will focus on the specific features of the individual embodiments that distinguish the particular embodiments from other embodiments.

[0016]

[0032] As used herein, the term "about," when referring to a value or amount of mass, weight, time, volume, pH, size, concentration, or percentage, means, in some embodiments, a variation of ±20%, in some embodiments ±10%, in some embodiments ±5%, in some embodiments ±1%, in some embodiments ±0.5%, and in some embodiments ±0.1% from the specified amount, and thus the variations are appropriate for practicing the disclosed methods.

[0017]

[0033] It should be understood that all of the maximum numerical limitations given throughout this specification include all lower numerical limitations as if such lower numerical limitations were expressly written herein. All of the minimum numerical limitations given throughout this specification include all higher numerical limitations as if such higher numerical limitations were expressly written herein. All numerical ranges given throughout this specification include all narrower numerical ranges that fall within such broader numerical ranges as if such narrower numerical ranges were all expressly written herein.

[0018]

[0034] As used herein, including the appended claims, "treating" a disease or condition, or "treatment" thereof, refers to the administration of one or more drugs to a patient (human, standard or non-standard or other mammal), the use of an implantable device, and / or the performance of procedures, which may include the use of devices for treating a disease, such as microscopic discectomy devices used to remove portions of a bulge disc or herniated disc and / or bone spur, in an attempt to alleviate the signs or symptoms of the disease or condition. Alleviation can occur prior to the appearance of the signs or symptoms of the disease or condition, as well as after their appearance. Thus, treating or treatment includes preventing or the prevention of a disease or unwanted condition (e.g., preventing the onset of a disease in a patient who may be susceptible to the disease but has not yet been diagnosed as having the disease). Further, treating or treatment specifically includes procedures that do not require complete alleviation of signs or symptoms and do not require a cure and have only a limiting effect on the patient. Treatment can include suppressing a disease, e.g., halting its development, or reducing a disease, e.g., causing regression of the disease. For example, treatment can include reducing acute or chronic inflammation, alleviating pain, and reducing and inducing the regrowth of new ligaments, bone, and other tissues as an adjunct in surgery and / or any reconstructive procedure. Similarly, as used herein, including the appended claims, the term "tissue" includes soft tissue, muscle, ligament, tendon, cartilage, and / or bone unless otherwise specifically referenced.

[0019]

[0035] The following discussion includes an explanation of an artificial device and related methods of using the artificial device in accordance with the principles of the present disclosure. Alternative embodiments are also disclosed. Reference will be made in detail to the exemplary embodiments of the present disclosure shown in the accompanying drawings. Referring to FIGS. 1-10, for example, the components of an artificial device, such as the system shown in FIG. 1A, are shown.

[0020]

[0036] Surgical techniques for occipitocervical and atlantoaxial fixation are used to treat the instability involving the occipitocervical (O-C1) and atlantoaxial (C1-2) joints following odontectomy. However, this often requires a separate incision to perform fusion and fixation via a posterior approach, resulting in a loss of mobility, particularly external rotation of the head. Implantation of an atlantoaxial artificial device may help reduce ventral brainstem compression while maintaining movement and reducing the time spent under anesthesia. Referring to FIGS. 1A-1C, the present invention includes an artificial device 10 comprising an artificial odontoid replacement 30 fixed to the body of C2 by two cantilever screws (not shown) inserted through screw holes 50. The artificial device 10 also includes a bracket 20 that replaces the anterior arch of C1 and is fixed to the lateral mass of C1 by two screws (not shown) inserted through bracket screw holes 40. These components are placed through a transnasal passage following endoscopic transnasal odontectomy. Both components have a profile small enough to pass through the transnasal passage. Once placed, the device will reconstruct the atlantoaxial joint by replacing the bony elements removed during odontectomy.

[0021]

[0037] The device of the present invention provides means to enable ventral brainstem compression while maintaining the mobility of the craniovertebral joints in patients who require odontoidectomy. Implantation of this prosthesis through a minimally invasive approach is expected to help minimize pain, scarring, length of hospital stay, and postoperative disability. The ability to maintain the movement of the atlantoaxial joint may be beneficial to the patient from the perspective of quality of life (while driving, by looking at the blind spot, the lane can be safely changed). The present invention can be used in patients who require odontoidectomy. In this population, instrumentation enables the patient to be treated by a single-stage approach instead of requiring a secondary procedure for posterior fixation. Collectively, these advancements will result in a reduction in pain, disability, and the surgical time required, with an expected concomitant reduction in patient mobility and maintained quality of life.

[0022] Method of Use

[0038] In one embodiment, the surgical system of the present invention is implanted as follows. The O-C1 joint is first exposed through a transnasal approach using a lower U-shaped nasopharyngeal flap. The anterior arch of C1 and the odontoid process are then removed. Next, the odontoid replacement is positioned and fixed to the body of C2 using two cantilever screws. Subsequently, the bracket is positioned at the location where the anterior arch of C1 previously existed and fixed in place using two C1 lateral mass screws placed under neuronavigation guidance.

[0023]

[0039] In one embodiment, the odontoid replacement and C1 bracket are made of titanium or a similar biocompatible material. Additionally, the odontoid replacement and C1 bracket may have an antibiotic coating to reduce the risk of infection due to a clean-contaminated passage. Further, the odontoid replacement is designed to mimic the shape and size of the odontoid while maintaining a footprint small enough to be placed through the transnasal passage. Static and fatigue load analysis may be performed to robustify the bracket and odontoid design for the patient's lifetime. The anterior arch bracket is similarly designed to reconstruct the anterior arch of C1. By reconstructing, the joint itself will be reconstructed by reconstructing the bone elements removed during odontoidectomy (see FIGS. 1B and 9).

[0024]

[0040] The current standard for treating irreducible brainstem compression is shown in FIG. 2. The figure shows occipitocervical fixation after odontoidectomy. Such a procedure results in a 40% loss of flexion-extension and a 60% loss of axial rotation. FIG. 3A shows an enlarged image of C1-C2 before segmentation. FIG. 3B shows C1-C2 after segmentation.

[0025]

[0041] FIG. 1B shows one embodiment of the anterior arch bracket of the present invention. FIG. 1C shows the odontoid replacement, and FIG. 1A shows the system in its configuration after implantation. The odontoid replacement is fixed to the body of C2 and then to the anterior arch bracket attached to the lateral mass of C1 by two lateral mass screws. This configuration allows flexion, extension, and external rotation at the atlantoaxial joint, thereby maintaining movement. Strong fixation of the implant will prevent instability.

[0026]

[0042] The length of the screw used to attach the bracket and odontoid replacement is predetermined by the individual patient's anatomical structure.

[0027]

[0043] Figure 9 is an image of the bracket according to the present invention attached to C1. Figure 10 is an image of the odontoid replacement according to the present invention attached to C2 after odontectomy.

[0028] Example

Example

[0029]

[0044] Four cadaver specimens were investigated to determine the average dimensions of the anterior arch of C1 and the odontoid process of C2. C1 and C2 were evaluated using a transnasal inverted U-shaped nasopharyngeal flap. Figures 4 and 5 show the dimensions of C1 used for the analysis. In the case of the C1 measurement results, H1 is the height of the anterior arch of C1, T1 is the thickness of the anterior arch of C1, L1 is the average distance across the entire ridge (determined using polygon modeling with Siemens NX software), and L2 is the horizontal distance of the anterior presentation of C1.

[0030]

[0045] Table 1 shows the measurement results taken from four specimens.

[0031]

Table 1

[0032]

[0046] In the case of the C2 measurement results, H1 is 70% of the height of the pre-operative odontoid. The lowest point was determined as the widest part of the curve in front of the LM. T1 is the thickness of C2. L1 is the horizontal distance of bone removal of C1 required to perform odontectomy.

[0033]

[0047] Table 2 shows the measurement results taken from four specimens.

[0034]

Table 2

Example

[0035]

[0048] Two embodiments of the bracket of the present invention were formed and tested. Embodiment 1 is shown in FIG. 7A. The figure shows an image of the bracket. The height of different parts of the bracket is shown in shading with values detailed in the adjacent chart. Embodiment 2 is shown in FIG. 7B, which has a similar image of the bracket and a table of adjacent values. These brackets were tested for various parameters including deformation, stress, reaction force, fatigue life, and safety factor. As shown in Table 3, Embodiment 2 of the bracket worked well for all parameters.

[0036]

Table 3

Example

[0037]

[0049] Four embodiments of the artificial tooth protrusion replacement of the present invention were formed and tested. Embodiment 1 is shown in FIG. 8A. The figure shows an image of the tooth protrusion replacement. The height of different parts of the tooth protrusion replacement is shown in shading with values detailed in the adjacent chart. Embodiment 2 is shown in FIG. 8B, which has a similar image of the tooth protrusion replacement and a table of adjacent values. Embodiment 3 is shown in FIG. 8C and Embodiment 4 is shown in FIG. 8D. These tooth protrusion replacements were tested for various parameters including deformation, stress, reaction force, fatigue life, and safety factor. Based on the values shown in Table 4, Embodiment 2 was determined to be the tooth protrusion replacement with the best average performance across all parameters.

[0038]

Table 4

[0039]

[0050] Various embodiments of the present invention have been shown and described, and further adaptations of the methods and systems described herein may be achieved by appropriate modifications by those skilled in the art without departing from the scope of the present invention. For example, the examples, embodiments, geometric shapes, materials, dimensions, and the like discussed above are illustrative and not essential. Accordingly, it is understood that the scope of the present invention should be considered with respect to the appended claims and is not limited to the details of the structures and operations shown and described in this specification and the drawings.

Claims

1. An artificial device for supporting the atlantoaxial joint between the C1 vertebra and the C2 vertebra after a odontoidectomy procedure that results in a C1 vertebra without an anterior arch and a C2 vertebra without an odontoid process, a. An artificial odontoid replacement that can be fixed to the C2 vertebra by at least two screws, b. A bracket for replacing the anterior arch of the C1 vertebra, which can be fixed to the lateral mass of the C1 vertebra by at least two screws, comprising a bracket, The bracket is an artificial device that can engage the odontoid replacement fixed to the C2 vertebra when fixed to the C1 vertebra.

2. The artificial device according to claim 1, wherein the artificial odontoid replacement can be fixed to the C2 vertebra by at least two cantilever screws.

3. The artificial device according to claim 1, wherein the artificial odontoid replacement contains titanium.

4. The artificial device according to claim 1, wherein the bracket contains titanium.

5. The artificial device according to claim 1, wherein the artificial odontoid replacement and the bracket contain an antibiotic coating.

6. A method for implanting an artificial odontoid into the C2 vertebra, a. Performing an endoscopic transnasal odontoidectomy procedure in which the anterior arch of the patient is removed from the patient's C1 vertebra and the odontoid process of the patient is removed from the patient's C2 vertebra; b. Implanting the artificial odontoid replacement of claim 1 through the transnasal passage of the patient; c. Positioning and fixing the artificial odontoid replacement to the patient's C2 vertebra at the location where the odontoid process previously existed; d. Implanting the bracket of claim 1 through the transnasal passage of the patient; e. Positioning and fixing the bracket to the patient's C1 vertebra at the location where the anterior arch of C1 previously existed; f. Engaging the bracket with the artificial odontoid replacement. A method comprising.

7. In the method according to claim 6, the odontoidectomy procedure comprises: a. Exposing the patient's O-C1 joint through the transnasal passage using a lower U-shaped nasopharyngeal flap; b. Removing the anterior arch of the patient's C1 vertebra and the odontoid process of the patient's C2 vertebra. A method comprising.

8. The method according to claim 6, wherein the tooth protrusion replacement is fixed to the C2 vertebra by at least two cantilever screws.

9. The method according to claim 6, wherein the bracket is fixed to the C1 vertebra by at least two cantilever screws.

10. The method according to claim 9, wherein the bracket is fixed to the C1 vertebra using neuronavigation guidance.

11. The method according to claim 6, wherein the artificial tooth protrusion replacement contains titanium.

12. The method according to claim 6, wherein the bracket contains titanium.

13. The method according to claim 6, wherein the artificial tooth protrusion replacement and the bracket contain an antibiotic coating.

Images