US20110087292A1 - Occipital fixation assembly, system and method for attaching the same - Google Patents

Abstract

An occipital fixation assembly is provided. The occipital fixation assembly includes a first mounting plate configured for placement within a sinus cavity adjacent a rear portion of a skull of a patient. A threaded post extends from the first mounting plate. A coupling member includes an aperture configured to receive the threaded post therethrough. The coupling member includes an offset extension configured to support a surgical rod thereon. A fixation nut configured to threadably engage the threaded post of the first mounting plate is rotatable about the threaded post and translatable therealong. The fixation nut is rotatable with respect to the first mounting plate and the coupling member such that rotation of the fixation nut in a predetermined direction brings the first mounting plate and the coupling member toward one another and into secured engagement with the skull of a patient.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS
• The present application claims the benefit of and priority to U.S. Provisional Application No. 61/278,925 to Sandhu et al., filed on Oct. 14, 2009, the entire contents of which are incorporated by reference herein.
BACKGROUND
• 1. Technical Field
• The present disclosure relates to an occipital fixation assembly, system and method for attaching the same. More particularly, the present disclosure relates to an occipital fixation assembly that is configured to support a surgical implant thereon and securely anchor to an inside of a skull of a patient.
• 2. Description of Related Art
• As is commonly known in the art, an occipitocervical junction includes an occiput, atlas and axis. The occipitocervical junction is a unique interface between the cranium and cervical spine. More than 50% of the rotation and flexion-extension are provided from this region. Ligaments in this region must resist forces about all six degrees of freedom. Moreover, instrumentation constructs not only must resist forces in all of these vectors, but also must resist the significant moment created by the suboccipital bone and the cervical spine, which meet at a 50° angle. Any instrumentation construct designed for use in this region must, therefore, have adequate geometry to interface with the osseous structures of the spinal structures as well as have sufficient rigidity and purchase to resist these forces until bone fusion can occur.
• At one time, occipitocervical instability and lesions located at the occipitocervical junction were considered inoperable and terminal. Since the first description of an occipitocervical fusion, multiple methods of fusion in this region have been described. Descriptions of simple bone gratis with halo immobilization; wire, pin, or hook constructs; rigid metallic loops and rectangles fixed to the bone with either screws or wires; and most recently, plate or rod constructs with screws have all been described. In general the evolution of this technology has focused on providing increasingly more rigid constructs to facilitate bone fusion and to minimize the need for and duration of external immobilization.
• A common technique for fixing occipitocervical instability is the use of an inverted Y-shaped screw plate. Using this technique, the plate is secured to C1-2 with transarticular screws and to the suboccipital bone with paramedian screws; the suboccipital bone varies in thickness, with a mean thickness of 14 mm. Screws must be carefully selected to provide adequate purchase, yet avoid cerebella injury. Utilizing the maximum screw length possible is critical because shorter screws have decreased resistance to pullout. If stabilization is required below the C1-2 level, then lateral mass screws can be placed through additional holes in a longer plate to include these levels as well. In certain instances, a bone graft may be added to promote fusion. The Y-shaped plate, in combination with transarticular screws, is an economical alternative. Immediate postoperative stabilization is achieved and very low rates of pseudarthrosis have been reported. Due to the risk of selecting the correct screw size and the potential for cerebellar injury along with the potential for screw pull-out due to the short nature of the screw lengths allowed for use, it may prove advantageous to provide an occipital fixation assembly, and a system and method for attaching the same that can reduce the chance for pull-out and reduce the risk for cerebellar injury.
SUMMARY
• The present disclosure provides an occipital fixation assembly. The occipital fixation assembly includes a first mounting plate configured for placement within a sinus cavity adjacent a rear portion of a skull of a patient. A threaded post extends from the first mounting plate. A coupling member includes an aperture configured to receive the threaded post therethrough and an offset extension configured to support a surgical rod thereon. A fixation nut, configured to threadably engage the threaded post of the first mounting plate, is rotatable about the threaded post and translatable therealong. The fixation nut is rotatable with respect to the first mounting plate and the coupling member such that rotation of the fixation nut in a predetermined direction brings the first mounting plate and the coupling member toward one another and into secured engagement with the skull of a patient.
• The present disclosure provides an occipital fixation system or system for attaching an occipital fixation assembly to a patient for subsequent attachment of a surgical rod thereto. The system includes a first mounting plate configured for placement within a sinus cavity adjacent a rear portion of a skull of a patient. The first mounting plate has a threaded post that extends therefrom. A coupling member includes an aperture configured to receive the threaded post therethrough. An offset extension disposed in parallel orientation with respect to the threaded post is configured to support a surgical rod thereon. A fixation nut configured to threadably engage the threaded post is rotatable about the threaded post and translatable therealong. The fixation nut is rotatable with respect to the first mounting plate and the coupling member such that rotation of the fixation nut in a predetermined direction brings the first mounting plate and the coupling member toward one another and into secured engagement with the skull of a patient. A forceps is configured to grasp a portion of the threaded post when the threaded post has been inserted through an aperture that has been previously drilled in the sinus cavity. A wrench assembly is adapted to engage and, subsequently, rotate the fixation nut about the threaded post.
• The present disclosure also provides a method for attaching an occipital fixation assembly to a patient for subsequent attachment of a surgical rod thereto. The method includes creating an aperture within a sinus cavity adjacent a rear portion of a skull of a patient. A threaded post of a first mounting plate of an occipital fixation assembly is, subsequently, positioned through the aperture created within the sinus cavity. Thereafter, a coupling member of the occipital fixation assembly is attached to the threaded post of the first mounting plate. A fixation nut is then positioned about the threaded post and, subsequently, rotated in a predetermined direction about the threaded post such that the first mounting plate and the coupling member move toward one another and into secured engagement with the skull of a patient. A surgical rod is coupled to the coupling member.
BRIEF DESCRIPTION OF THE DRAWINGS
• Various embodiments of the present disclosure are described herein with reference to the drawings wherein:
• FIG. 1 is a perspective view of an occipital fixation assembly with a surgical rod secured thereon according to an embodiment of the present disclosure;
• FIG. 2 is a front view of the occipital fixation assembly depicted inFIG. 1;
• FIG. 3 is an exploded view of the occipital fixation assembly depicted inFIG. 1 with components separated;
• FIG. 4 is an exploded view of a coupling member associated with the occipital fixation assembly depicted inFIG. 1;
• FIG. 5 is a perspective view of an alternative configuration of the occipital fixation assembly depicted inFIG. 1;
• FIG. 6 is a front view of the occipital fixation assembly depicted inFIG. 5;
• FIGS. 7A-7C are perspective views illustrating a mounting plate of the occipital fixation assembly depicted inFIG. 5 with the mounting plate shown in various configurations;
• FIG. 7D is a cross-sectional view of the mounting plate depicted in the configuration ofFIG. 7A taken along section line7D-7D;
• FIG. 8A is a perspective view of an alternative embodiment of a threaded post that may be utilized with the occipital fixation assembly depicted inFIG. 1;
• FIG. 8B is a side view of the threaded post depicted inFIG. 8A;
• FIG. 9 is a perspective view of a surgical instrument grasping the threaded post depicted inFIG. 8A;
• FIG. 10 is an enlarged area of detail depicted inFIG. 9;
• FIGS. 11A-11D are perspective views illustrating an occipital fixation system and method for attaching the occipital fixation assembly to a patient for subsequent attachment of a surgical rod thereto;
• FIG. 12A is a cross-sectional view of a coupling member according to another embodiment of the present disclosure; and
• FIG. 12B an enlarged area of detail depicted inFIG. 12B.
DETAILED DESCRIPTION
• In the following description, as is traditional, the term “proximal” refers to a portion of a surgical instrument closer to the operator while the term “distal” refers to a portion of a surgical instrument farther from the operator. In addition, the term “cephalad” is used in this application to indicate a direction toward a patient's head, whereas the term “caudad” indicates a direction toward the patient's feet. Further still, for the purposes of this application, the term “medial” indicates a direction toward the middle of the body of the patient, whilst the term “lateral” indicates a direction toward a side of the body of the patient (i.e., away from the middle of the body of the patient). The term “posterior” indicates a direction toward the patient's back, and the term “anterior” indicates a direction toward the patient's front. In the following description, well-known functions or constructions are not described in detail to avoid obscuring the present disclosure in unnecessary detail.
• With reference toFIGS. 1-7C, and initially with reference toFIG. 1, anoccipital fixation assembly2 is illustrated. Theoccipital fixation assembly2 is positionable within a sinus cavity adjacent a rear portion of the skull, lateral to a brain stem region, i.e., adjacent the occiput. To this end, theoccipital fixation assembly2 includes afirst mounting plate4, acoupling member6 and a fixation nut8.
• Continuing with reference toFIG. 1, the mountingplate4 is illustrated. Mountingplate4 includes a generally elongated configuration having top andbottom surfaces10 and12, respectively. In the illustrated embodiments, the mountingplate4 includes a slight curvature or concavity “C” (seeFIG. 2 for example) that is configured to follow a contour of the occiput of a skull. As can be appreciated, this curvature or concavity facilitates anchoring the mountingplate4 to the occiput.
• One or more barbs (twobarbs20aand20bare shown in the drawings) are operably disposed on thetop surface10 of the mounting plate4 (FIG. 1).Barbs20aand20bare configured to facilitate anchoring the mountingplate4 into an interior surface of the skull of a patient and to minimize rotation of the mountingplate4 when the fixation nut8 is rotated about a threaded post14a(FIGS. 1-5) or movement of the mountingplate4 when installed in the occiput. Thebarbs20aand20binclude a generally conical configuration with a substantially pointed tip.
• In one particular embodiment, to facilitate fixation of the mountingplate4 to an interior surface of a skull, thebarbs20aand20bmay reside in generallycircumferential recesses21aand21b, respectively, seeFIGS. 5-7C. Therecesses21aand21bare configured to engage soft tissue that may be disposed adjacent the interior surface of the skull. Thebarbs20aand20bare set into therecesses21aand21bat a depth that allows a majority of a surface area of thebarbs20aand20bto sufficiently anchor into the interior surface of the skull.
• With reference again toFIG. 1, the elongated post14aextends in a generally orthogonal orientation from thetop surface10 such that the mountingplate4 has a generally “T” shape (FIG. 3). The elongated post14amay be monolithically formed with the mountingplate4 or may be coupled to the mountingplate4 by one or more suitable coupling methods, e.g., welded to thetop surface10 of the mountingplate4. In the illustrated embodiments, the elongated post14ais monolithically formed with the mountingplate4.
• A plurality ofthreads16aextends along an outer circumferential surface of the elongated post14a. The plurality ofthreads16aextends along a majority of a length of the elongated post such that a portion of the elongated post14aadjacent thetop surface10 of the mountingplate4 is devoid of the plurality ofthreads16a(FIGS. 2 and 3). This portion of the elongated post devoid of the plurality ofthreads16aserves as a relief for cutting the plurality ofthreads16a. Moreover, this portion of theelongated post16adevoid of the plurality of threads allows amountng plate5 to be threaded over the threadedpost16auntil the mountingplate5 passes the plurality ofthreads16awhere it can be rotated 360° (seeFIG. 7A in combination withFIG. 7B) without advancing in or out of the occiput when being deployed into a final position (FIG. 7C), described in greater detail below. In certain instances, this portion of the elongated post devoid of the plurality of threads is intended to prevent “over-tightening” of thecoupling member6 to the elongated post14a.
• In the embodiment illustrated inFIGS. 1-7C, a proximal end of the threaded post14aincludes a slot17 (FIGS. 1 and 3) that is configured to receive a working end of a driving device, e.g., a screwdriver (or the like), that is configured to rotate the mountingplate4 with respect to the fixation nut8 when the fixation nut8 is positioned on the threaded post14a. The driving tool may include a blade configured for receipt in theslot17 for holding the mountingplate4 in a desired orientation while the fixation nut8 is rotated about the threaded post14a. Additionally, theslot17 turns the threaded post14a(and, thus, the mounting plate4) after the mountingplate5 is pulled and set to the inside surface of the occiput (withbarbs20cand20d) to the final deployed cross position (FIG. 7C), described in greater detail below.
• Continuing with reference toFIG. 1, thecoupling member6 is illustrated. Couplingmember6 is configured to operably couple to the mounting plate4 (or, in some instances, to mountingplate4 and asecond mounting plate5, seeFIGS. 5-7C) and to engage an exterior surface of a skull. To these ends,coupling member6 includes abase member36.
• Base36 includes a generally annular configuration defined by an outerperipheral wall35 that joins respective bottom andtop surfaces31 and33 (FIGS. 1-4) to each other.Bottom surface31 includes one or more barbs, e.g., threebarbs20e-20g, disposed thereon (seeFIG. 2 in combination withFIG. 4) that are configured in a manner as described above with respect tobarbs20a-20b. However, unlikebarbs20a-20bthat are configured to anchor into an interior surface of the skull,barbs20e-20gare configured to anchor to an exterior surface of the skull.Top surface33 is configured to support the fixation nut8 thereon. An aperture32 (FIGS. 3 and 4) extends from thetop surface33 to thebottom surface31 and is configured to receive the threaded post14a(or in certain embodiments, a threaded post14b, described in greater detail below) and a portion of the fixation nut8 therethrough.
• Couplingmember6 is also configured to support the surgical rod “R” thereon (FIG. 1). To this end,coupling member6 includes an offset extension34 (FIGS. 1-4).
• Offsetextension34 is disposed in parallel orientation with respect to the threaded post14a(or in some embodiments with respect to the threaded post14b), seeFIGS. 1-3 and5-7. The offsetextension34 includes a generally elongated slot38 (FIGS. 3 and 4) having an intermittent threaded portion40 (FIGS. 3 and 4 show one half of the intermittent threaded portion40) configured to receive a set-screw42 (FIGS. 1-3) therein and a non-threaded portion44 (FIGS. 3 and 4) configured to receive the surgical rod “R” therein (FIGS. 1 and 2). The threaded and non-threaded portions,40 and44, respectively, of the offsetextension34 are arranged such that when the surgical rod “R” is secured thereto, the surgical rod “R” is oriented perpendicular to the set-screw42 (FIGS. 1 and 2).
• With reference again toFIG. 1, the fixation nut8 is shown. Fixation nut8 is configured to threadably engage the threaded post14aof the mounting plate4 (or in some instances threaded post14b(FIG. 8A)). Fixation nut8 is rotatable about the threaded post14aand translatable therealong. Moreover, fixation nut8 is rotatable with respect to the mountingplate4 and thecoupling member6 such that rotation of the fixation nut8 in a predetermined direction, e.g., a clockwise direction, brings the mountingplate4 and thecoupling member6 toward one another and into secured engagement with the skull of a patient.
• Preferably, a bottom surface48 of the fixation nut8 includes a generally elongatedextension50 that is configured to extend into anaperture52 of awasher54 and theaperture32 of the base36 (FIG. 4). Theextension50 is configured to facilitate positioning the fixation nut8 about the threaded post14a(or threaded post14b) and thewasher54 distributes or “spreads” a load of the fixation nut8 evenly across thetop surface33 of thebase member36 when the fixation nut is rotated about the threaded post14a. In the embodiment illustrated inFIG. 4, the washer56 has a generally conical shape and is also intended to serve as a lock washer. While the fixation nut8 and washer56 have been described herein as two separate components that couple to thecoupling member6, it is within the purview of the present disclosure that thecoupling member6, fixation nut8 and washer56 may be formed as one integral component.
• To facilitate fixation of occipital fixation assembly2ato an interior surface of a skull, asecond mounting plate5 may be operably coupled to the mountingplate4, seeFIGS. 5-7C. To this end, the mountingplate5 includes anopening23 of suitable dimension, seeFIGS. 7A-7C. More particularly, theopening23 includes an outer diameter that is less than an outer diameter defined by an outer edge of the plurality ofthreads16a. The mountingplate5 is rotatable about the threaded post14asuch that the mountingplate5 may be rotated from a first position, e.g., a “nested position,” (FIGS. 7A and 7D) that is conducive for positioning the mountingplates4 and5 adjacent to an interior surface of a skull, to a subsequent or anchoring position (FIGS. 7B-7C) that is conducive for securing or lagging the mountingplates4 and5 to the interior surface of a skull. In the anchoring position, the mountingplates4 and5 may be disposed transverse to each other and form a generally crisscross or “X” shape or configuration, as best seen inFIG. 7C.
• Mountingplate5 includes one or more barbs, e.g.,barbs20cand20d, disposed on atop surface30 thereof. As described above with respect tobarbs20aand20b,barbs20cand20dmay reside in correspondingrecesses21cand21d, respectively, seeFIGS. 5-7C).
• To facilitate positioning the mountingplates4 and5 inside the occiput, abottom surface28 of the mountingplate5 includes a pair of indents25aand25bthat are configured to releasably engage thebarbs20aand20b(FIG. 7D); the indents25aand25bare shown engaged with thebarbs20aand20b, respectively and, as a result thereof, are not explicitly shown. In the “nested” position, the mountingplate5 and the mountingplate4 can be inserted together into an aperture or slot in the occiput and rotated together until a final position, e.g., an anchored position, is achieved for the mountingplate5, which can be seated or anchored into the occiput by pulling the nested mountingplates4 and5 so that thebarbs20cand20don the mountingplate5 “dig” into the inside of the occiput. Subsequently, the mountingplate4 can be deployed to the final (cross) position (FIG. 7C) using theslot17 in the end of the threaded bolt. More particularly, the operable end of a screwdriver may be utilized to engage theslot17 and, subsequently, turn the mountingplate4 that disengages thebarbs20aand20bfrom the respective indents25aand25b. Thebarbs20aand20bon the mountingplate4 may then be brought into contact with the inside of the occiput, thus, fixing both mountingplates4 and5 in place.
• To facilitate anchoring the mountingplates4 and5 into the interior surface of a skull, abottom surface28 of the mountingplate5 includes a notchedportion24 that is configured to receive and/or mate with a portion, e.g., a corresponding notchedportion26 disposed on thetop surface10, of the mounting plate4 (FIGS. 7B and 7D). In the anchored position, the notchedportions24 and26 enable thetop surface10 of the mounting plate andtop surface30 of the mountingplate5 to be flush with each other, as best seen inFIG. 7D; this provides a substantially uniform contact surface between the mountingplates4 and5 and the interior surface of the skull. This substantially uniform contact surface facilitates positioning thebarbs20a-20dadjacent to the interior surface of the skull, which, in turn, ensures that thebarbs20a-20dproperly engage the interior surface of skull. As can be appreciated, having all thebarbs20a-20dproperly engaged to the interior surface of the skull reduces and/or eliminates the likelihood of inadvertent movement of the mountingplates4 and5 after the occipital fixation assembly2ahas been affixed to the interior surface of the skull.
• In use, an aperture is, initially, created within a sinus cavity adjacent a rear portion of a skull of a patient, i.e., adjacent the occiput. For purposes herein, the aperture may be created utilizing one or more suitable surgical devices, e.g., a surgical drill.
• Mountingplate4 is positioned through the aperture created within the sinus cavity adjacent the occiput. Thereafter,coupling member6 is positioned about the threaded post14a(seeFIG. 1 in combination withFIG. 3). In particular, once the physician creates the desired opening the patient's skull, one end of the mountingplate4 is inserted through the opening until the opposing end clears the surface of the skull and can be positioned beneath the surface of the skull. Subsequently, the mountingplate4 is moved in a generally opposing direction such that the entire mountingplate4 is disposed beneath the surface of the skull (i.e. on the inside). Once positioned, the threaded post14aextends through the opening. This installation technique is applicable to all disclosed embodiments of the occipital fixation assembly. As will be appreciated, the opening will have a dimension that is slightly greater than the dimensions of the mountingplate4.
• The fixation nut8 including thewasher54 is positioned about the threaded post14aand over thebase36 ofcoupling member6. For illustrative purposes, the fixation nut8 includingwasher54 is shown engaged with thecoupling member6. Subsequently, the fixation nut8 is rotated in a predetermined direction, e.g., a clockwise direction, about the threaded post14a. In one particular embodiment, a screwdriver (or other suitable device) is utilized to engage theslot17 to facilitate rotation the mountingplate4 and/or fixation nut8. Rotation of the fixation nut8 about the threaded post14bcauses thecoupling member6 and the mountingplate4 to move toward one another and into secured engagement with an interior and exterior surface, respectively, of the skull of a patient. As a result thereof, the occiput is “sandwiched” between the surgical rod coupling member6 (withbarbs20e-20g) and mounting plate4 (withbarbs20a-20b) by threading the fixation nut8 over the threaded post14aand tightening to the specified torque.
• In some surgical scenarios, the occiput is “sandwiched” between the surgical rod coupling member6 (withbarbs20e-20g) and mountingplates4 and5 (withbarbs20a-20d) by threading the fixation nut8 over the threaded post14aand tightening to the specified torque.
• Thereafter, the surgical rod “R” is coupled to the offsetextension34 of thecoupling member6 and secured to thecoupling member6 via theset screw42.
• As can be appreciated, the combination of theunique mounting plate4 having the threaded post14aconfigured to couple to thecoupling member6 reduces and/or eliminates the likelihood of theoccipital fixation assembly2 inadvertently pulling out from the occiput, which, in turn, reduces the risk for cerebellar injury. Moreover, anchoring thebarbs20a-20band thebarbs20e-20ginto the interior and exterior surfaces, respectively, of the skull diminishes the likelihood of inadvertent rotation of mountingplate4 andcoupling member6 after the surgical rod “R” has been attached to the occipital fixation assembly and/or the spine.
• With reference toFIGS. 8A and 8B, an alternate embodiment of an elongated post is designated elongated post14b. In this embodiment, the elongated post14bis provided without theslot17. More particularly, unlike the elongated post14a, elongated post14bincludes a plurality of non-continuous threads16bextending partially along an outer circumferential surface of the elongated post14b. A proximal end of the elongated post14bincludes a threadedaperture19 that extends into the threaded post14b(FIG. 8A). The threadedaperture19 is configured to receive one end of a surgical device, e.g.,wrench assembly80, for positioning and turning the fixation nut8 about the threaded post14b(FIGS. 11A-11D). Anon-threaded aperture21 extends traverse to the threadedaperture19 and is configured to receive one end of a surgical device, e.g., aforceps60, for grasping the threaded post14band maintaining the mountingplate4ain a non-rotatable state when the fixation nut8 is rotated about the elongated post14b(FIGS. 9-11B).
• With reference toFIGS. 9-11D,system100 includes a forceps60 (FIGS.9 and11A-11C), a wrench assembly80 (FIGS. 11A-11D) and the occipital fixation assembly2b(FIG. 11D) that includes the mountingplate4awith the threaded post14b(FIG. 10).
• Forceps60 is configured to grasp a portion of the threaded post14b(as best seen inFIG. 10). More particularly, theforceps60 may be utilized to grasp the threaded post14bto facilitate positioning the mountingplate4 within the aperture created within the sinus cavity adjacent a rear portion of a skull of a patient, i.e., the occiput. Moreover, and as noted above,forceps60 may be utilized to grasp the threaded post14bto maintain the mountingplate4ain a non-rotatable state when the fixation nut8 is rotated about the elongated post14b.Forceps60 includes first andsecond shafts61 and62. Eachshaft61 and62 has arespective jaw member63 and64 extending from a distal end thereof and ahandle65 and66 disposed at a proximal end thereof for effecting movement of thejaw members63 and64 relative to one another about apivot67. Thejaw members63 and64 are movable from a first position (FIG. 11C) wherein thejaw members63 and64 are disposed in spaced relation relative to one another to a second position wherein thejaw members63 and64 cooperate to grasp the threaded post (FIGS. 9-11B).
• Each of thejaw members63 and64 includes a respectiveinner facing surface69 and68 (FIGS. 10 and 11C) having a respectiveproximal end70 and71 (FIG. 9) and a respectivedistal end72 and73 that is offset from theproximal end70 and71 (FIG. 10). In the closed configuration, the distal ends72 and73 of the inner facing surfaces69 and68 remain spaced-apart from each other to facilitate grasping the threaded post therebetween (FIGS. 9-11A).
• The distal ends72 and73 of thejaw members63 and64 include aprotrusion74 and75 (FIGS. 10 and 11C) thereon that is configured to releasably engage thenon-threaded aperture21 on the threaded post14b.
• A ratchet mechanism90 may be operably coupled to theshafts61 and62 adjacent thehandles65 and66 and is configured to maintain thejaw members63 and64 in one or more positions. More particularly, eachshaft61 and62 includes a respective ratchet component90aand90beach having a plurality of ratchet teeth that are configured to matingly engage with one another.
• As can be appreciated, in the instance where theoccipital fixation assembly2 includes a mountingplate4 with a threaded post14a, the inner facing surfaces69 and68 of theforceps60 may be provided without theprotrusions74 and75. For example, the inner facing surfaces69 and68 offorceps60 may include one or more slots or grooves that are configured to matingly engage with the plurality ofthreads16aon the threaded post14a.
• Wrench assembly80 is configured to rotate the fixation nut8 about the threaded post14b(FIGS. 11B and 11C).Wrench assembly80 includes acoupling member81 that is configured to threadably engage the threadedaperture19 on the threaded post14bof the mounting plate4 (FIGS. 11A-11C).Wrench assembly80 includes awrench head member82 that is selectively and coaxially engageable with the coupling member81 (FIGS. 11A-11C).
• Thecoupling member81 includes a generally elongated shaft83 (FIGS. 11A and 11D) having a threaded distal end84 (FIGS. 11A and 11C), andproximal end85 that is configured to rotate the threadeddistal end84 into the threadedaperture19 of the threaded post14bof the mountingplate4afor securement of the coupling member to the mountingplate4.
• A portion86 (FIGS. 11A and 11D) of thecoupling member81 proximate to the threadeddistal end84 has an outer diameter that is slightly smaller than an inner diameter of the fixation nut8, so that the fixation nut8 can slide overportion86. Theportion86 is configured to facilitate positioning the fixation nut8 on the threaded post14bof the mountingplate4a. More particularly, theportion86 is configured to guide the fixation nut8 into position on the threaded post14b. In one particular embodiment, theelongated extension50 of the fixation nut8 is configured to slide over theportion86 and guide the fixation nut8 into position on the threaded post14b
• Theproximal end85 of thecoupling member81 is complementary shaped to receive an open end of a turn-key87. In the illustrated embodiment, theproximal end85 and the open end of the turn-key87 include a hexagonal shape. The turn-key87 is configured to facilitate rotation of the threadeddistal end84 into the threadedaperture19 on the threaded post14bof the mountingplate4a.
• In the embodiment illustrated inFIGS. 11A-11D, aportion88 of theshaft81 proximate to the threadeddistal end84 is textured or otherwise treated to provide an additional gripping surface for a user, or to provide mechanical interface for maintaining the turn-key87 at theproximal end85.
• Thewrench head member82 is configured to releasably engage the fixation nut8 and rotate the fixation nut8 about the threaded post14bof the mountingplate4a. To this end, thewrench head member82 is complementary shaped to receive and turn the fixation nut8. In the embodiment illustrated inFIGS. 11A-11D, aproximal end89 of thewrench head member82 is textured or otherwise treated to facilitate rotation of the wrench member head. As can be appreciated, thewrench head member82 may be utilized to rotate the fixation nut8 about the threaded post14a.
• Operation of thesystem100 including the occipital fixation assembly2bincluding the mountingplate4awith the threaded post14bis described in terms of use of a method for attaching the occipital fixation assembly2bfor subsequent attachment of a surgical rod “R” thereto.
• An aperture is created within a sinus cavity adjacent a rear portion of a skull of a patient. For purposes herein, the aperture may be created utilizing one or more suitable surgical devices, e.g., a surgical drill.
• Theforceps60 may be utilized for grasping the threaded post14bto insert the mountingplate4athrough the aperture created within the sinus cavity and to temporarily hold the threaded post14bin place (FIGS. 9-11B). Thereafter,coupling member6 is positioned about the threaded post14b.
• The fixation nut8 including thewasher54 is positioned about the threaded post14band over thebase36 ofcoupling member6. To facilitate positioning the fixation nut8 about the threaded post14b, thecoupling member81 of thewrench assembly80 may be coupled to the threaded post14b, seeFIG. 11A where thecoupling member81 is shown adjacent the threaded post14bjust before coupling thecoupling member81 to the threaded post14b. The turn-key may be utilized to facilitate turning thecoupling member81 about the threaded post14b.
• Subsequently, the fixation nut8 is rotated in a predetermined direction, e.g., a clockwise direction, about the threaded post14b. To facilitate rotating the fixation nut8 about the threaded post14b, thewrench head member82 may be positioned coaxially about thecoupling member81 and into engagement with the fixation nut8 (FIG. 11B). It should be noted that once the fixation nut8 has been engaged to the threaded post14b, theforceps60 may be removed from engagement with the threaded post14b(FIG. 11C). It is further contemplated that the threaded engagement between to threadeddistal end84 and the threadedaperture19 may be opposed to the threaded engagement between fixation nut8 and post14b(i.e., one may engage in a clockwise direction and the other in a counterclockwise direction) so that as the fixation nut8 is tightened thecoupling member6 does not loosen from the threaded post14b. In this manner, even after theforceps60 have been removed, control may be exerted over the threaded post14bas the fixation nut8 is tightened.
• Thewrench head member82 is rotated about the fixation nut8, which, in turn, rotates the fixation nut8 about the threaded post14b, this in turn, causes thecoupling member6 and the mountingplate4ato move toward one another and into secured engagement with an interior and exterior surface, respectively, of the skull of a patient.
• In one surgical scenario, after thecoupling member6 and the mountingplate4aare moved into secured engagement with the interior and exterior surface of the skull, thewrench assembly80 is removed from the occipital fixation assembly2 (FIG. 11D). Thereafter, the surgical rod “R” is coupled to the offsetextension34 of thecoupling member6 and secured to thecoupling member6 via theset screw42.
• From the foregoing and with reference to the various figure drawings, those skilled in the art will appreciate that certain modifications can also be made to the present disclosure without departing from the scope of the same. For example, in some embodiments theslot38 of the offsetextension34 includes a taper locking mechanism for capturing the surgical rod “R” such that aset screw42 is not required.
• In yet another embodiment, theslot38 of the offsetextension34 includes a polyaxial coupling for capturing the surgical rod “R” such that an angle and trajectory of the surgical rod “R” does not limit the position of theoccipital fixation assembly2.
• In yet another embodiment, a fixation nut may be integrally formed with a coupling member. More particularly, and with reference toFIGS. 12A and 12B, a coupling member6A and afixation nut8A are integrally formed with one another via one or more suitable coupling methods, e.g., soldering, brazing or welding. In this instance, thefixation nut8A is swaged, but rotatable, to thecoupling member8A along with a washer making it an integral assembly. In this instance, the coupling member6A including thefixation nut8A are positioned about the threaded post14bsimultaneously.
• While several embodiments of the disclosure have been shown in the drawings and/or discussed herein, it is not intended that the disclosure be limited thereto, as it is intended that the disclosure be as broad in scope as the art will allow and that the specification be read likewise. Therefore, the above description should not be construed as limiting, but merely as exemplifications of particular embodiments. Those skilled in the art will envision other modifications within the scope and spirit of the claims appended hereto.

Claims (25)

1. An occipital fixation assembly, comprising:

a first mounting plate configured for placement within a sinus cavity adjacent a rear portion of a skull of a patient, the first mounting plate having a threaded post extending therefrom;

a coupling member including an aperture configured to receive the threaded post therethrough, the coupling member including an offset extension disposed in parallel orientation with respect to the threaded post and configured to support a surgical rod thereon; and

a fixation nut configured to threadably engage the threaded post of the first mounting plate, the fixation nut rotatable about the threaded post and translatable therealong, the fixation nut rotatable with respect to the first mounting plate and the coupling member such that rotation of the fixation nut in a predetermined direction brings the first mounting plate and the coupling member toward one another and into secured engagement with the skull of a patient.

2. An occipital fixation assembly according toclaim 1, wherein at least one barb is operably disposed on a top surface of the first mounting plate and at least one barb is operably disposed on a bottom surface of the coupling member.

3. An occipital fixation assembly according toclaim 2, wherein the at least one barb operably disposed on the top surface of the first mounting plate and the at least one barb operably disposed on the bottom surface of the coupling member each configured to anchor into an inside of the skull and outside of the skull, respectively, to minimize respective rotation of the first mounting plate and coupling member when the fixation nut is rotated about the threaded post.

4. An occipital fixation assembly according toclaim 1, wherein a washer is disposed between the fixation nut and the aperture on the coupling member and serves as a lock washer.

5. An occipital fixation assembly according toclaim 4, wherein a bottom surface of the fixation nut is receivable through the washer and at least partially extends through the aperture of the coupling member, wherein the fixation nut is swaged to the coupling member making the coupling member and fixation nut an integral assembly.

6. An occipital fixation assembly according toclaim 1, wherein the offset extension includes a generally elongated slot having a threaded portion configured to receive a set-screw therein and a non-threaded portion configured to receive the surgical rod therein, the threaded and non-threaded portions of the offset extension arranged such that when the surgical rod is secured thereto, the surgical rod is oriented perpendicular to the set-screw.

7. An occipital fixation assembly according toclaim 1, wherein a second mounting plate is operably coupled to the first mounting plate and is rotatable about the threaded post.

8. An occipital fixation assembly according toclaim 7, wherein a bottom surface of the second mounting plate is notched and configured to receive at least a portion of the first mounting plate therein such that a top surface of the first mounting plate and a top surface of the second mounting plate are flush with each other and the first and second mounting plates are disposed traverse to each other when the first and second mounting plates are attached to a skull of a patient.

9. An occipital fixation assembly according toclaim 8, wherein the bottom surface of the second mounting plate includes a pair of indents configured to releasably receive a corresponding pair of barbs operably disposed on the top surface of the first mounting plate, the pair of indents configured to maintain the first mounting plate in a relatively fixed orientation with respect to the second mounting plate to facilitate positioning the first and second mounting plates inside a skull.

10. An occipital fixation assembly according toclaim 1, wherein the threaded post of the first mounting plate includes a threaded aperture and a non-threaded aperture that extends traverse to the threaded aperture, the threaded aperture configured to receive one end of a surgical device for turning the fixation nut about the threaded post, and the non-threaded aperture configured to receive one end of a surgical device for grasping the threaded post.

11. An occipital fixation system, comprising:

an occipital fixation assembly, including:

a first mounting plate configured for placement within a sinus cavity adjacent a rear portion of a skull of a patient, the first mounting plate having a threaded post extending therefrom;

a coupling member including an aperture configured to receive the threaded post therethrough, the coupling member including an offset extension disposed in parallel orientation with respect to the threaded post and configured to support a surgical rod thereon;

a fixation nut configured to threadably engage the threaded post, the fixation nut rotatable about the threaded post and translatable therealong, the fixation nut rotatable with respect to the first mounting plate and the coupling member such that rotation of the fixation nut in a predetermined direction brings the first mounting plate and the coupling member toward one another and into secured engagement with the skull of a patient;

a forceps configured to grasp a portion of the threaded post to facilitate positioning the first mounting plate through an aperture that has been previously drilled in the sinus cavity; and

a wrench assembly configured to engage and, subsequently, rotate the fixation nut about the threaded post.

12. An occipital fixation system according toclaim 11, wherein at least one barb is operably disposed on a top surface of the first mounting plate and at least one barb is operably disposed on a bottom surface of the coupling member.

13. An occipital fixation system according toclaim 12, wherein the at least one barb operably disposed on the top surface of the first mounting plate and the at least one barb operably disposed on the bottom surface of the coupling member each configured to anchor into an inside of the skull and outside of the skull, respectively, to minimize respective rotation of the first mounting plate and coupling member when the fixation nut is rotated about the threaded post.

14. An occipital fixation system according toclaim 11, wherein a washer is disposed between the fixation nut and the aperture on the coupling member and serves as a lock washer, wherein a bottom surface of the fixation nut is receivable through the washer and at least partially extends through the aperture of the coupling member, wherein the fixation nut is swaged to the coupling member making the coupling member and fixation nut an integral assembly.

15. An occipital fixation system according toclaim 11, wherein the offset extension includes a generally elongated slot having a threaded portion configured to receive a set-screw therein and a non-threaded portion configured to receive the surgical rod therein, the threaded and non-threaded portions of the offset extension arranged such that when the surgical rod is secured thereto, the surgical rod is oriented perpendicular to the set-screw.

16. An occipital fixation system according toclaim 11, wherein a second mounting plate is operably coupled to the first mounting plate and is rotatable about the threaded post.

17. An occipital fixation system according toclaim 16, wherein in a bottom surface of the second mounting plate is notched and configured to receive at least a portion of the first mounting plate therein such that a top surface of the first mounting plate and a top surface of the second mounting plate are flush with each other and the first and second mounting plates are disposed traverse to each other when the first and second mounting plates are attached to a skull of a patient.

18. An occipital fixation assembly according toclaim 17, wherein the bottom surface of the second mounting plate includes a pair of indents configured to releasably receive a corresponding pair of barbs operably disposed on the top surface of the first mounting plate, the pair of indents configured to maintain the first mounting plate in a relatively fixed orientation with respect to the second mounting plate to facilitate positioning the first and second mounting plates inside a skull.

19. An occipital fixation system according toclaim 11, wherein the threaded post of the first mounting plate includes a threaded aperture and a non-threaded aperture that extends traverse to the threaded aperture, the threaded aperture configured to receive one end of a surgical device for turning the fixation nut about the threaded post and the non-threaded aperture configured to receive one end of a surgical device for grasping the threaded post.

20. An occipital fixation system according toclaim 19, wherein the forceps includes first and second shafts each having a jaw member extending from a distal end thereof and a handle disposed at a proximal end thereof for effecting movement of the jaw members relative to one another about a pivot, the jaw members movable from a first position wherein the jaw members are disposed in spaced relation relative to one another to a second position wherein the jaw members cooperate to grasp the threaded post.

21. An occipital fixation system according toclaim 20, wherein each of the jaw members are curved and includes an inner facing surface having a proximal end and a distal end that is offset from the proximal end such that in the closed configuration the distal ends of the inner facing surfaces remain spaced-apart from each other to facilitate grasping the threaded post therebetween, at least one of distal ends of the jaw members including a protrusion thereon that is configured to releasably engage the non-threaded aperture on the threaded post.

22. An occipital fixation system according toclaim 20, wherein the wrench assembly comprises:

a coupling member configured to threadably engage the threaded aperture on the threaded post of the first mounting plate; and

a wrench head member selectively and coaxially engageable with the coupling member, the wrench head member configured to releasably engage the fixation nut and rotate the fixation nut about the threaded post of the first mounting plate,

wherein the proximal end of the coupling member is complementary shaped to receive an end of a turn-key for facilitating rotation of the threaded distal end into the threaded aperture of the threaded post of the first mounting plate.

23. An occipital fixation system according toclaim 22, wherein the coupling member includes a generally elongated shaft having a threaded distal end, and proximal end that is configured to rotate the threaded distal end into the threaded aperture of the threaded post of the first mounting plate for securement of the coupling member to the first mounting plate.

24. An occipital fixation system according toclaim 23, wherein a portion of the coupling member proximate to the threaded distal end has an outer diameter that is slightly smaller than an inner diameter of the fixation nut8, the portion of the coupling member proximate to the threaded distal end configured to facilitate positioning the fixation nut on the threaded post of the first mounting plate.

25. A method for attaching an occipital fixation assembly for subsequent attachment of a surgical rod thereon, comprising:

creating an aperture within a sinus cavity adjacent a rear portion of a skull of a patient;

positioning a first mounting plate of an occipital fixation assembly through the aperture created within the sinus cavity;

attaching a coupling member of the occipital fixation assembly to the threaded post of the first mounting plate;

positioning a fixation nut about the threaded post and, subsequently, rotating the fixation nut in a predetermined direction thereabout such that the first mounting plate and the coupling member move toward one another and into secured engagement with the skull of a patient; and

coupling a surgical rod to the coupling member.

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