Cervical spinal fixation assembly for laminar screws

Abstract

A spinal fixation assembly for use with a cervical fixation rod and methods of use thereof. The spinal fixation assembly can comprise a washer comprising a first side and a second side opposing the first side, the first side comprising a first set of teeth arranged longitudinally, the second side comprising a second set of teeth arranged circumferentially and a laminar wing comprising a slot configured to receive a fastener therethrough, wherein the laminar wing extends laterally from the cervical fixation rod when coupled thereto, the laminar wing adjustably coupled to the cervical fixation rod via the washer such that the first set of teeth are configured to allow a longitudinal position of the laminar wing to be adjusted relative to the cervical fixation rod and the second set of teeth are configured to allow an orientation of the laminar wing to be adjusted relative to the cervical fixation rod.

Description

CERVICAL SPINAL FIXATION ASSEMBLY FOR LAMINAR SCREWSCROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application claims the benefit of priority under 35 U.S.C. §119(e) of U.S. Provisional Application No. 63 / 531,504, filed August 8, 2023. The disclosure of the prior application is considered part of an is herein incorporated by reference in the disclosure of this application in its entirety.BACKGROUND OF THE INVENTIONFIELD OF THE INVENTION

[0002] The present invention relates generally to cervical spinal fixation spinal fixation assemblies and methods of use of the same.BACKGROUND INFORMATION

[0003] Spinal fusion is a surgical procedure whereby two or more vertebrae are fused together to prevent movement therebetween in order to address various issues caused by the movement of the adjoining vertebrae. The spine is divided into cervical (neck), thoracic (middle back), and lumbar (lower back) sections. The cervical spine consists of seven bones (Cl to C7 vertebrae). Based on biomechanical and anatomical characteristics, the cervical spine is divided in axial (CO through C2) and subaxial levels (C3 through C7). Instrumented posterior cervical fusion procedures are performed using titanium hardware consisting of various screws and rods that are intraoperatively secured to the vertebrae. The standard anchor point for placement screws in the subaxial and axial spine is the lateral mass, which is the bony junction between the superior and inferior articular processes. At C2, the lateral mass is called the pars interarticularis. The axial spine is extremely important for the motion of the neck: 50% of the cervical spine rotation occurs between Cl and C2 and 50% of the flexion / extension of the cervical spine occurs between Cl and CO. Therefore, improvements to the surgical instrumentation for performing posterior cervical fusion procedures could improve intraoperative efficiency, reduce patient recovery times, and generally improve patient outcomes for such procedures, thereby maximizing the ability of surgeons to maintain the rotation and flexion / extension movements of patients’ necks.

[0004] In instrumented posterior cervical fusion procedures, the spinal hardware constructs typically extend at least two levels above and at least two levels below the point of instability.Given the relative weak fixation obtained in the lateral masses, it can often be desirable to extend the spinal hardware constructs three levels above and three levels below the instability point in the cervical spine. Current spinal hardware system consists of screws with polyaxial tulips that accommodate a rod to link the screws and immobilize the cervical segments. Depending on the patient’s anatomy and pathology, the lateral mass of C2 is not an ideal point of fixation. Accordingly, the lamina of C2 is used as an alternative fixation point. However, a screw affixed to the lamina of C2 is not aligned to the other lateral mass screws. Connecting the rods to the tulip of the screw in the lamina of C2 is difficult and sometimes requires several hours to achieve adequate rod bending, adding surgeon’s fatigue, causing additional bleeding, and significantly increasing the duration of the operation. Therefore, there is particularly a need for improved surgical spinal fixation hardware that is particularly adapted to allow the positioning of the components to be more easily adjusted intraoperatively, thereby allowing the spinal fixation system to accommodate patients’ anatomies and pathologies more easily. Such improved systems could also allow the hardware to be affixed at more convenient attachment points that are not currently surgically feasible, such as the lateral mass of C2.SUMMARY OF THE INVENTION

[0005] The present disclosure provides a cervical spinal fixation spinal fixation assemblies and methods of use of the same. The systems and methods described herein could be used in connection with, for example, cervical spinal fusion procedures.

[0006] In some embodiments, the present disclosure provides a spinal fixation assembly for use with a cervical fixation rod, the spinal fixation assembly comprising: a washer comprising a first side and a second side opposing the first side, the first side comprising a first set of teeth arranged longitudinally, the second side comprising a second set of teeth arranged circumferentially; and a laminar wing comprising a slot configured to receive a fastener therethrough, wherein the laminar wing extends laterally from the cervical fixation rod when coupled thereto, the laminar wing adjustably coupled to the cervical fixation rod via the washer such that the first set of teeth are configured to allow a longitudinal position of the laminar wing to be adjusted relative to the cervical fixation rod and the second set of teeth are configured to allow an orientation of the laminar wing to be adjusted relative to the cervical fixation rod.

[0007] In some embodiments, the present disclosure provides a method of a method of attaching a spinal fixation assembly to a spine via a cervical fixation rod, the spinal fixation assembly comprising a washer comprising a first side and a second side opposing the first side, the first side comprising a first set of teeth arranged longitudinally, the second side comprising a second set of teeth arranged circumferentially, and a laminar wing comprising a slot configured to receive a fastener therethrough, wherein the laminar wing extends laterally from the cervical fixation rod when coupled thereto, the laminar wing adjustably coupled to the cervical fixation rod via the washer such that the first set of teeth are configured to allow a longitudinal position of the laminar wing to be adjusted relative to the cervical fixation rod and the second set of teeth are configured to allow an orientation of the laminar wing to be adjusted relative to the cervical fixation rod, the method comprising: affixing a lateral mass fastener to a lateral mass of a vertebra; affixing the cervical fixation rod to the fastener such that the cervical fixation rod extends at least a defined distance from the fastener; identifying an entry point for a laminar screw; decorticating the entry point for the laminar screw; applying the spinal fixation assembly such that the slot is positioned over the entry point; inserting the laminar screw through the slot into a lamina of the vertebra; and tightening the spinal fixation assembly to a locked configuration.

[0008] In some embodiments, the cervical fixation rod comprises at least one of a 3.5 mm cervical fixation rod or a 4.0 mm cervical fixation rod.

[0009] In some embodiments, the first side comprises a superior side and the second side comprises an inferior side relative to a spine to which the spinal fixation assembly is being attached.

[0010] In some embodiments, the fastener comprises a laminar fixation screw.

[0011] In some embodiments, the spinal fixation assembly further comprises a clip, wherein the clip is configured to engage with the cervical fixation rod and adjustably engage with the washer.

[0012] In some embodiments, the clip comprises a set of teeth configured to adjustably engage with the second set of teeth of the washer.

[0013] In some embodiments, the clip is configured to engage with the cervical fixation rod via a friction fit.

[0014] In some embodiments, the spinal fixation assembly further comprises a cap affixable to the fastener, the cap configured to prevent backout of the fastener.

[0015] In some embodiments, the spinal fixation assembly further comprises a screw configured to be received by the washer for coupling the laminar wing to the washer; and a nut configured to engage with the screw, the nut configured to secure the laminar wing in place relative to the cervical fixation rod.

[0016] In some embodiments, the slot of the laminar wing is configured to allow the fastener to be adjustably oriented at a defined angle range relative to the cervical fixation rod.

[0017] In some embodiments, the defined angle range is from about plus 20 degrees to about negative 20 degrees relative to a perpendicular axis from the cervical fixation rod.

[0018] In some embodiments, the laminar wing is configured to not bend or change angles under normal physiological tension in a spine.

[0019] In some embodiments, the defined distance is from about 7 mm to about 10 mm.

[0020] In some embodiments, decorticating the entry point for the laminar screw comprises using a high-speed drill to decorticate the entry point.BRIEF DESCRIPTION OF THE DRAWINGS

[0021] FIG. 1A shows a first perspective view of a cervical spinal fixation assembly, in accordance with an embodiment of the present disclosure.

[0022] FIG. IB shows a second perspective view of the cervical spinal fixation assembly of FIG. 1 A, in accordance with an embodiment of the present disclosure.

[0023] FIG. 1C shows a third perspective view of the cervical spinal fixation assembly of FIG. 1 A, in accordance with an embodiment of the present disclosure.

[0024] FIG. ID shows a fourth perspective view of the cervical spinal fixation assembly of FIG. 1 A, in accordance with an embodiment of the present disclosure.

[0025] FIG. IE shows a fifth perspective view of the cervical spinal fixation assembly of FIG. 1 A, in accordance with an embodiment of the present disclosure.

[0026] FIG. IF shows a sixth perspective view of the cervical spinal fixation assembly of FIG. 1 A, in accordance with an embodiment of the present disclosure.

[0027] FIG. 1G shows a seventh perspective view of the cervical spinal fixation assembly of FIG. 1 A, in accordance with an embodiment of the present disclosure.

[0028] FIG. 1H shows an eighth perspective view of the cervical spinal fixation assembly of FIG. 1 A, in accordance with an embodiment of the present disclosure.

[0029] FIG. II shows a ninth perspective view of the cervical spinal fixation assembly of FIG. 1 A, in accordance with an embodiment of the present disclosure.

[0030] FIG. 2A shows an exploded view of the cervical spinal fixation assembly of FIG. 1A, in accordance with an embodiment of the present disclosure.

[0031] FIG. 2B shows a reverse exploded view of the cervical spinal fixation assembly of FIG. 1 A, in accordance with an embodiment of the present disclosure.

[0032] FIG. 3 shows various views of the washer of the cervical spinal fixation assembly of FIG. 1 A, in accordance with an embodiment of the present disclosure.

[0033] FIG. 4 shows various views of the slotted clip of the cervical spinal fixation assembly of FIG. 1A, in accordance with an embodiment of the present disclosure.DETAILED DESCRIPTION OF THE INVENTION

[0034] The present disclosure is generally directed to spinal fixation assemblies and methods of use of the same. In particular, the present is disclosure is directed to cervical spinal fixation assembly that could be used in connection with a cervical fusion procedure (e.g., a posterior cervical spinal fusion) and methods for assembling and intraoperatively using the spinal fixation assembly.

[0035] As generally discussed above, there are a number of difficulties with current surgical spinal fixation hardware. For example, it can be particularly intraoperatively challenging to link the hardware affixed to vertebrae adjoining C2. In order to overcome these difficulties and to allow preservation of the C1-C2 motion, described herein is a spinal fixation assembly that can allow both lateral mass screws in the pars / pedicle at C2 and a strong fixation in the C2 lamina to co-exist with the same cervical fixation rod. Allowing a double fixation at C2 adds significant strength to the construct, prevents pull out of the C2 pars / pedicle screw, reduces incidence of pseudarthrosis, and preserves the motion between Cl and C2 as Cl will not need to be included in the construct. Further, the described spinal fixation assembly that be used in conjunction with commercially available fasteners (e.g., lateral mass screws) and other spinal fixation hardware, thereby allowing the spinal fixation assembly to be easily integrated into surgical workflows.Spinal Fixation Assembly

[0036] Referring now to FIGS. 1A-2B, there are shown various views of a spinal fixation assembly 100 in assembled and exploded configurations. The spinal fixation assembly 100 could be used in, for example, posterior cervical fusion procedures. In one embodiment, the spinal fixation assembly 100 could be configured to be used in conjunction with a cervicalfixation rod 102 (e.g., a 3.5 mm or a 4.0 mm cervical fixation rod) or other such hardware that is utilized in posterior cervical fusion procedures. In one embodiment, the spinal fixation assembly 100 can include a laminar wing 104 including a slot 115 configured to receive a fastener 110 therethrough and a washer 114 (FIG. 3). The washer 114 is configured to allow the laminar wing 104 to be adjustably coupled to the cervical fixation rod 102. The fastener 110 could include, for example, a headless bolt that is configured to threadably engage with a corresponding nut 108 for securing the components of the spinal fixation assembly 100 to the cervical fixation rod 102, as depicted in FIGS. 2A and 2B. In one embodiment, the slot 115 can be elongated such that the lateral positioning of the laminar wing 104 can be adjusted relative to the fastener 110 (until secured in place via the nut 108, as in the depicted embodiment). In one embodiment, the spinal fixation assembly 100 can further include a backout prevention cap 106.

[0037] In one embodiment, the spinal fixation assembly 100 can further include a slotted clip 112 (FIG. 4) that is configured to secure the washer 114 and the other components of the spinal fixation assembly 100 to the cervical fixation rod 102. In addition to being depicted through FIGS. 1A-2B, various additional views of the slotted clip 112 are shown in FIG. 4. In an illustrative embodiment, the slotted clip 112 includes a slot that is configured to engage with the cervical fixation rod 102 and an interface (e.g., a set of teeth) that are configured to adjustably engage with the washer 114. In one embodiment, the slotted clip 112 can be positioned collinear with the lateral mass screws for the spine fixation procedure. The slotted clip 112 can be attachable to the cervical fixation rod 102 via a variety of different securement mechanisms, such as a friction fit. For example, the diameter of the slot of the slotted clip 112 could be 0.5 mm smaller than the corresponding diameter of the rod 102. The slotted clip 112 can further include internal threading that is configured to engage with the fastener 110 to allow the spinal fixation assembly 100 to be secured to the cervical fixation rod 102.

[0038] In addition to being depicted through FIGS. 1A-2B, various additional views of the washer 114 are shown in FIG. 3. The washer 114 can include a first side 114A (FIGS. 2A and 3) and a second side 114B (FIGS. 2B and 3) opposing the first side 112A. The first side 114A can be configured to adjustably engage with the laminar wing 104 and the second side 114B can be configured to adjustably engage with the slotted clip 112, thereby allowing the washer 114 to be interposed between the washer 114 and the laminar wing 104, while maintaining positional flexibility for all of the aforementioned components. In one embodiment, the firstside 114A includes a first set of teeth arranged longitudinally and the second side 114B includes a second set of teeth arranged circumferentially. In alternative embodiments, the sets of teeth could be arranged oppositely on the sides 114A, 114B. In further alternative embodiments, the sets of teeth could be arranged in alternative patterns. The laminar wing 104 is configured to extend laterally from the cervical fixation rod 102 when coupled thereto. The alternatively patterned sides of teeth on the opposing sides of the washer 114 allow the laminar wing 104 to be adjustably coupled to the cervical fixation rod 102. In particular, the longitudinally arranged teeth are configured to allow the laminar wing 104 to be adjusted longitudinally relative to the cervical fixation rod 102 and the circumferentially arranged teeth are configured to allow the laminar wing to be adjusted circumferentially relative to the cervical fixation rod 102. In other words, the multi -tooth design allows for the surgeon to adjust both the length and angle of attachment to the cervical fixation rod 102, while still allowing the spinal fixation assembly 100 to be locked in position when fastened without any positional drift over time. In one embodiment, the first side 114A could be the intraoperative superior side and the second side 114B could be the intraoperative inferior side relative to a spine to which the spinal fixation assembly 100 is being attached.

[0039] In one embodiment, the slot 115 of the laminar wing 104 can be configured to allow the orientation of the fastener 110 to be adjustably positioned at range of angles relative to the cervical fixation rod 102. In one illustrative embodiment, the defined angle range could be from about plus 20 degrees to about negative 20 degrees relative to a perpendicular axis from the cervical fixation rod 102.

[0040] In one embodiment, the laminar wing 104 is configured to not bend or change angles under normal physiological tension in the spine.Intraoperative Use of the Spinal Fixation Assembly

[0041] In the depicted embodiment, the spinal fixation assembly 100 is assembled by engaging the slotted clip 112 with the cervical fixation rod 102, engaging the washer 114 with the slotted clip 112 such that the longitudinal teeth on the first side 114A thereof are arranged to cause the laminar wing 104 to be positioned at the desired angle when engaged therewith, engaging the laminar wing 104 such that it is positioned at the desired angle, and then fastening the laminar wing 104 to the slotted clip 112 (and, thus, the cervical fixation rod 102) via tightening of the nut 108 onto the fastenerl lO. When intraoperatively secured in place, the laminar wing 104 extends along the vertebral lamina to a position close to the spinous processwhere the laminar anchor will be placed. The backout prevention cap 106 is intraoperatively fastened above the laminar anchor to prevent backout.

[0042] In one embodiment, a method of intraoperatively using (e.g., by a surgeon) the spinal fixation assembly 100 could include affixing a lateral mass fastener to a lateral mass of a vertebra and affixing the cervical fixation rod to the fastener such that the cervical fixation rod extends at least a defined distance (e.g., from about 7 mm to about 10 mm) from the lateral mass fastener. Further, the method could include identifying an entry point for a laminar screw (e.g., the fastener 110) and decorticating the entry point for the same. Still further, the method could include applying the spinal fixation assembly 100 such that the slot 115 is positioned over the entry point, inserting the laminar screw through the slot into a lamina of the vertebra, and tightening the spinal fixation assembly to a locked configuration (e.g., by tightening the nut 108). As discussed above, the spinal fixation assembly 100 could be beneficial when used for in connection with the C2 vertebra. In one embodiment, the entry point for the laminar screw could be decorticated via a high-speed drill.

[0043] Although the invention has been described with reference to the presently preferred embodiment, it should be understood that various modifications can be made without departing from the spirit of the invention. Accordingly, the invention is limited only by the following claims.

[0044] The following terms shall have, for the purposes of this application, the respective meanings set forth below. Unless otherwise defined, all technical and scientific terms used herein have the same meanings as commonly understood by one of ordinary skill in the art. Nothing in this disclosure is to be construed as an admission that the embodiments described in this disclosure are not entitled to antedate such disclosure by virtue of prior invention.

[0045] As used herein, the singular forms “a,” “an,” and “the” include plural references, unless the context clearly dictates otherwise. Thus, for example, reference to a “protein” is a reference to one or more proteins and equivalents thereof known to those skilled in the art, and so forth.

[0046] As used herein, the term “about” means plus or minus 10% of the numerical value of the number with which it is being used. Therefore, about 50 mm means in the range of 45 mm to 55 mm.

[0047] As used herein, the term “consists of’ or “consisting of’ means that the device or method includes only the elements, steps, or ingredients specifically recited in the particular claimed embodiment or claim.

[0048] In embodiments or claims where the term “comprising” is used as the transition phrase, such embodiments can also be envisioned with replacement of the term “comprising” with the terms “consisting of’ or “consisting essentially of.”

[0049] As used herein, the term “subject” includes, but is not limited to, humans and nonhuman vertebrates such as wild, domestic, and farm animals.

[0050] While the present disclosure has been illustrated by the description of exemplary embodiments thereof, and while the embodiments have been described in certain detail, it is not the intention of the Applicants to restrict or in any way limit the scope of the appended claims to such detail. Additional advantages and modifications will readily appear to those skilled in the art. Therefore, the disclosure in its broader aspects is not limited to any of the specific details, representative devices and methods, and / or illustrative examples shown and described. Accordingly, departures may be made from such details without departing from the spirit or scope of the Applicant’s general inventive concept.

[0051] With respect to the use of substantially any plural and / or singular terms herein, those having skill in the art can translate from the plural to the singular and / or from the singular to the plural as is appropriate to the context and / or application. The various singular / plural permutations may be expressly set forth herein for sake of clarity.

[0052] In addition, even if a specific number is explicitly recited, those skilled in the art will recognize that such recitation should be interpreted to mean at least the recited number (for example, the bare recitation of “two recitations,” without other modifiers, means at least two recitations, or two or more recitations). Furthermore, in those instances where a convention analogous to “at least one of A, B, and C, et cetera” is used, in general such a construction is intended in the sense one having skill in the art would understand the convention (for example, “a system having at least one of A, B, and C” would include but not be limited to systems that have A alone, B alone, C alone, A and B together, A and C together, B and C together, and / or A, B, and C together, et cetera). In those instances where a convention analogous to “at least one of A, B, or C, et cetera” is used, in general such a construction is intended in the sense one having skill in the art would understand the convention (for example, “a system having at least one of A, B, or C” would include but not be limited to systems that have A alone, B alone, Calone, A and B together, A and C together, B and C together, and / or A, B, and C together, et cetera). It will be further understood by those within the art that virtually any disjunctive word and / or phrase presenting two or more alternative terms, whether in the description, sample embodiments, or drawings, should be understood to contemplate the possibilities of including one of the terms, either of the terms, or both terms. For example, the phrase “A or B” will be understood to include the possibilities of “A” or “B” or “A and B.”

[0053] In addition, where features of the disclosure are described in terms of Markush groups, those skilled in the art will recognize that the disclosure is also thereby described in terms of any individual member or subgroup of members of the Markush group.

[0054] Various of the above-disclosed and other features and functions, or alternatives thereof, may be combined into many other different systems or applications. Various presently unforeseen or unanticipated alternatives, modifications, variations or improvements therein may be subsequently made by those skilled in the art, each of which is also intended to be encompassed by the disclosed embodiments.

[0055] Although the invention has been described with reference to the presently preferred embodiment, it should be understood that various modifications can be made without departing from the spirit of the invention. Accordingly, the invention is limited only by the following claims.

Claims

What Is Claimed Is:

1. A spinal fixation assembly for use with a cervical fixation rod, the spinal fixation assembly comprising: a washer comprising a first side and a second side opposing the first side, the first side comprising a first set of teeth arranged longitudinally, the second side comprising a second set of teeth arranged circumferentially; and a laminar wing comprising a slot configured to receive a fastener therethrough, wherein the laminar wing extends laterally from the cervical fixation rod when coupled thereto, the laminar wing adjustably coupled to the cervical fixation rod via the washer such that the first set of teeth are configured to allow a longitudinal position of the laminar wing to be adjusted relative to the cervical fixation rod and the second set of teeth are configured to allow an orientation of the laminar wing to be adjusted relative to the cervical fixation rod.

2. The spinal fixation assembly of claim 1, wherein the cervical fixation rod comprises at least one of a 3.5 mm cervical fixation rod or a 4.0 mm cervical fixation rod.

3. The spinal fixation assembly of claim 1 or claim 2, wherein the first side comprises a superior side and the second side comprises an inferior side relative to a spine to which the spinal fixation assembly is being attached.

4. The spinal fixation assembly of any one of claims 1-3, wherein the fastener comprises a laminar fixation screw.

5. The spinal fixation assembly of any one of claims 1-4, further comprising a clip, wherein the clip is configured to engage with the cervical fixation rod and adjustably engage with the washer.

6. The spinal fixation assembly of claim 5, wherein the clip comprises a set of teeth configured to adjustably engage with the second set of teeth of the washer.

7. The spinal fixation assembly of claim 5 or claim 6, wherein the clip is configured to engage with the cervical fixation rod via a friction fit.

8. The spinal fixation assembly of any one of claims 1-7, further comprising a cap affixable to the fastener, the cap configured to prevent backout of the fastener.

9. The spinal fixation assembly of any one of claims 1-8, further comprising: a screw configured to be received by the washer for coupling the laminar wing to the washer; and a nut configured to engage with the screw, the nut configured to secure the laminar wing in place relative to the cervical fixation rod.

10. The spinal fixation assembly of any one of claims 1-9, wherein the slot of the laminar wing is configured to allow the fastener to be adjustably oriented at a defined angle range relative to the cervical fixation rod.

11. The spinal fixation assembly of claim 10, wherein the defined angle range is from about plus 20 degrees to about negative 20 degrees relative to a perpendicular axis from the cervical fixation rod.

12. The spinal fixation assembly of any one of claims 1-11, wherein the laminar wing is configured to not bend or change angles under normal physiological tension in a spine.

13. A method of attaching a spinal fixation assembly to a spine via a cervical fixation rod, the spinal fixation assembly comprising a washer comprising a first side and a second side opposing the first side, the first side comprising a first set of teeth arranged longitudinally, the second side comprising a second set of teeth arranged circumferentially, and a laminar wing comprising a slot configured to receive a fastener therethrough, wherein the laminar wing extends laterally from the cervical fixation rod when coupled thereto, the laminar wing adjustably coupled to the cervical fixation rod via the washer such that the first set of teeth are configured to allow a longitudinal position of the laminar wing to be adjusted relative to the cervical fixation rod and the second set of teeth are configured to allow an orientation of the laminar wing to be adjusted relative to the cervical fixation rod, the method comprising: affixing a lateral mass fastener to a lateral mass of a vertebra;affixing the cervical fixation rod to the fastener such that the cervical fixation rod extends at least a defined distance from the fastener; identifying an entry point for a laminar screw; decorticating the entry point for the laminar screw; applying the spinal fixation assembly such that the slot is positioned over the entry point; inserting the laminar screw through the slot into a lamina of the vertebra; and tightening the spinal fixation assembly to a locked configuration.

14. The method of claim 13, wherein the vertebra is C2.

15. The method of claim 13 or claim 14, wherein the defined distance is from about 7 mm to about 10 mm.

16. The method of any one of claims 13-15, wherein decorticating the entry point for the laminar screw comprises using a high-speed drill to decorticate the entry point.

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