U.S. patent application number 12/904613 was filed with the patent office on 2011-04-14 for occipital fixation assembly, system and method for attaching the same.
This patent application is currently assigned to K2M, Inc.. Invention is credited to Larry McClintock, Faheem Sandhu, Kevin R. Strauss.
Application Number | 20110087292 12/904613 |
Document ID | / |
Family ID | 43855443 |
Filed Date | 2011-04-14 |
United States Patent
Application |
20110087292 |
Kind Code |
A1 |
Sandhu; Faheem ; et
al. |
April 14, 2011 |
OCCIPITAL FIXATION ASSEMBLY, SYSTEM AND METHOD FOR ATTACHING THE
SAME
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.
Inventors: |
Sandhu; Faheem; (Washington,
DC) ; Strauss; Kevin R.; (Leesburg, VA) ;
McClintock; Larry; (Gore, VA) |
Assignee: |
K2M, Inc.
Leesburg
VA
|
Family ID: |
43855443 |
Appl. No.: |
12/904613 |
Filed: |
October 14, 2010 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
61278925 |
Oct 14, 2009 |
|
|
|
Current U.S.
Class: |
606/264 ;
606/279 |
Current CPC
Class: |
A61B 17/8875 20130101;
A61B 17/7055 20130101; A61B 17/7082 20130101; A61B 17/8872
20130101; A61B 17/8888 20130101; A61B 2017/00738 20130101; A61B
17/282 20130101; A61B 17/808 20130101; A61B 17/809 20130101 |
Class at
Publication: |
606/264 ;
606/279 |
International
Class: |
A61B 17/70 20060101
A61B017/70; A61B 17/88 20060101 A61B017/88 |
Claims
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 to claim 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 to claim 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 to claim 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 to claim 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 to claim 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 to claim 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 to claim 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 to claim 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 to claim 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 to claim 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 to claim 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 to claim 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 to claim 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 to claim 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 to claim 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 to claim 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 to claim 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 to claim 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 to claim 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 to claim 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 to claim 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 to claim 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 nut 8, 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.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] 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
[0002] 1. Technical Field
[0003] 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.
[0004] 2. Description of Related Art
[0005] 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.degree. 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.
[0006] 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.
[0007] 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
[0008] 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.
[0009] 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.
[0010] 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
[0011] Various embodiments of the present disclosure are described
herein with reference to the drawings wherein:
[0012] 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;
[0013] FIG. 2 is a front view of the occipital fixation assembly
depicted in FIG. 1;
[0014] FIG. 3 is an exploded view of the occipital fixation
assembly depicted in FIG. 1 with components separated;
[0015] FIG. 4 is an exploded view of a coupling member associated
with the occipital fixation assembly depicted in FIG. 1;
[0016] FIG. 5 is a perspective view of an alternative configuration
of the occipital fixation assembly depicted in FIG. 1;
[0017] FIG. 6 is a front view of the occipital fixation assembly
depicted in FIG. 5;
[0018] FIGS. 7A-7C are perspective views illustrating a mounting
plate of the occipital fixation assembly depicted in FIG. 5 with
the mounting plate shown in various configurations;
[0019] FIG. 7D is a cross-sectional view of the mounting plate
depicted in the configuration of FIG. 7A taken along section line
7D-7D;
[0020] FIG. 8A is a perspective view of an alternative embodiment
of a threaded post that may be utilized with the occipital fixation
assembly depicted in FIG. 1;
[0021] FIG. 8B is a side view of the threaded post depicted in FIG.
8A;
[0022] FIG. 9 is a perspective view of a surgical instrument
grasping the threaded post depicted in FIG. 8A;
[0023] FIG. 10 is an enlarged area of detail depicted in FIG.
9;
[0024] 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;
[0025] FIG. 12A is a cross-sectional view of a coupling member
according to another embodiment of the present disclosure; and
[0026] FIG. 12B an enlarged area of detail depicted in FIG.
12B.
DETAILED DESCRIPTION
[0027] 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.
[0028] With reference to FIGS. 1-7C, and initially with reference
to FIG. 1, an occipital fixation assembly 2 is illustrated. The
occipital fixation assembly 2 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, the occipital
fixation assembly 2 includes a first mounting plate 4, a coupling
member 6 and a fixation nut 8.
[0029] Continuing with reference to FIG. 1, the mounting plate 4 is
illustrated. Mounting plate 4 includes a generally elongated
configuration having top and bottom surfaces 10 and 12,
respectively. In the illustrated embodiments, the mounting plate 4
includes a slight curvature or concavity "C" (see FIG. 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 mounting plate 4 to the occiput.
[0030] One or more barbs (two barbs 20a and 20b are shown in the
drawings) are operably disposed on the top surface 10 of the
mounting plate 4 (FIG. 1). Barbs 20a and 20b are configured to
facilitate anchoring the mounting plate 4 into an interior surface
of the skull of a patient and to minimize rotation of the mounting
plate 4 when the fixation nut 8 is rotated about a threaded post
14a (FIGS. 1-5) or movement of the mounting plate 4 when installed
in the occiput. The barbs 20a and 20b include a generally conical
configuration with a substantially pointed tip.
[0031] In one particular embodiment, to facilitate fixation of the
mounting plate 4 to an interior surface of a skull, the barbs 20a
and 20b may reside in generally circumferential recesses 21a and
21b, respectively, see FIGS. 5-7C. The recesses 21a and 21b are
configured to engage soft tissue that may be disposed adjacent the
interior surface of the skull. The barbs 20a and 20b are set into
the recesses 21a and 21b at a depth that allows a majority of a
surface area of the barbs 20a and 20b to sufficiently anchor into
the interior surface of the skull.
[0032] With reference again to FIG. 1, the elongated post 14a
extends in a generally orthogonal orientation from the top surface
10 such that the mounting plate 4 has a generally "T" shape (FIG.
3). The elongated post 14a may be monolithically formed with the
mounting plate 4 or may be coupled to the mounting plate 4 by one
or more suitable coupling methods, e.g., welded to the top surface
10 of the mounting plate 4. In the illustrated embodiments, the
elongated post 14a is monolithically formed with the mounting plate
4.
[0033] A plurality of threads 16a extends along an outer
circumferential surface of the elongated post 14a. The plurality of
threads 16a extends along a majority of a length of the elongated
post such that a portion of the elongated post 14a adjacent the top
surface 10 of the mounting plate 4 is devoid of the plurality of
threads 16a (FIGS. 2 and 3). This portion of the elongated post
devoid of the plurality of threads 16a serves as a relief for
cutting the plurality of threads 16a. Moreover, this portion of the
elongated post 16a devoid of the plurality of threads allows a
mountng plate 5 to be threaded over the threaded post 16a until the
mounting plate 5 passes the plurality of threads 16a where it can
be rotated 360.degree. (see FIG. 7A in combination with FIG. 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
the coupling member 6 to the elongated post 14a.
[0034] In the embodiment illustrated in FIGS. 1-7C, a proximal end
of the threaded post 14a includes a slot 17 (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
mounting plate 4 with respect to the fixation nut 8 when the
fixation nut 8 is positioned on the threaded post 14a. The driving
tool may include a blade configured for receipt in the slot 17 for
holding the mounting plate 4 in a desired orientation while the
fixation nut 8 is rotated about the threaded post 14a.
Additionally, the slot 17 turns the threaded post 14a (and, thus,
the mounting plate 4) after the mounting plate 5 is pulled and set
to the inside surface of the occiput (with barbs 20c and 20d) to
the final deployed cross position (FIG. 7C), described in greater
detail below.
[0035] Continuing with reference to FIG. 1, the coupling member 6
is illustrated. Coupling member 6 is configured to operably couple
to the mounting plate 4 (or, in some instances, to mounting plate 4
and a second mounting plate 5, see FIGS. 5-7C) and to engage an
exterior surface of a skull. To these ends, coupling member 6
includes a base member 36.
[0036] Base 36 includes a generally annular configuration defined
by an outer peripheral wall 35 that joins respective bottom and top
surfaces 31 and 33 (FIGS. 1-4) to each other. Bottom surface 31
includes one or more barbs, e.g., three barbs 20e-20g, disposed
thereon (see FIG. 2 in combination with FIG. 4) that are configured
in a manner as described above with respect to barbs 20a-20b.
However, unlike barbs 20a-20b that are configured to anchor into an
interior surface of the skull, barbs 20e-20g are configured to
anchor to an exterior surface of the skull. Top surface 33 is
configured to support the fixation nut 8 thereon. An aperture 32
(FIGS. 3 and 4) extends from the top surface 33 to the bottom
surface 31 and is configured to receive the threaded post 14a (or
in certain embodiments, a threaded post 14b, described in greater
detail below) and a portion of the fixation nut 8 therethrough.
[0037] Coupling member 6 is also configured to support the surgical
rod "R" thereon (FIG. 1). To this end, coupling member 6 includes
an offset extension 34 (FIGS. 1-4).
[0038] Offset extension 34 is disposed in parallel orientation with
respect to the threaded post 14a (or in some embodiments with
respect to the threaded post 14b), see FIGS. 1-3 and 5-7. The
offset extension 34 includes a generally elongated slot 38 (FIGS. 3
and 4) having an intermittent threaded portion 40 (FIGS. 3 and 4
show one half of the intermittent threaded portion 40) configured
to receive a set-screw 42 (FIGS. 1-3) therein and a non-threaded
portion 44 (FIGS. 3 and 4) configured to receive the surgical rod
"R" therein (FIGS. 1 and 2). The threaded and non-threaded
portions, 40 and 44, respectively, of the offset extension 34 are
arranged such that when the surgical rod "R" is secured thereto,
the surgical rod "R" is oriented perpendicular to the set-screw 42
(FIGS. 1 and 2).
[0039] With reference again to FIG. 1, the fixation nut 8 is shown.
Fixation nut 8 is configured to threadably engage the threaded post
14a of the mounting plate 4 (or in some instances threaded post 14b
(FIG. 8A)). Fixation nut 8 is rotatable about the threaded post 14a
and translatable therealong. Moreover, fixation nut 8 is rotatable
with respect to the mounting plate 4 and the coupling member 6 such
that rotation of the fixation nut 8 in a predetermined direction,
e.g., a clockwise direction, brings the mounting plate 4 and the
coupling member 6 toward one another and into secured engagement
with the skull of a patient.
[0040] Preferably, a bottom surface 48 of the fixation nut 8
includes a generally elongated extension 50 that is configured to
extend into an aperture 52 of a washer 54 and the aperture 32 of
the base 36 (FIG. 4). The extension 50 is configured to facilitate
positioning the fixation nut 8 about the threaded post 14a (or
threaded post 14b) and the washer 54 distributes or "spreads" a
load of the fixation nut 8 evenly across the top surface 33 of the
base member 36 when the fixation nut is rotated about the threaded
post 14a. In the embodiment illustrated in FIG. 4, the washer 56
has a generally conical shape and is also intended to serve as a
lock washer. While the fixation nut 8 and washer 56 have been
described herein as two separate components that couple to the
coupling member 6, it is within the purview of the present
disclosure that the coupling member 6, fixation nut 8 and washer 56
may be formed as one integral component.
[0041] To facilitate fixation of occipital fixation assembly 2a to
an interior surface of a skull, a second mounting plate 5 may be
operably coupled to the mounting plate 4, see FIGS. 5-7C. To this
end, the mounting plate 5 includes an opening 23 of suitable
dimension, see FIGS. 7A-7C. More particularly, the opening 23
includes an outer diameter that is less than an outer diameter
defined by an outer edge of the plurality of threads 16a. The
mounting plate 5 is rotatable about the threaded post 14a such that
the mounting plate 5 may be rotated from a first position, e.g., a
"nested position," (FIGS. 7A and 7D) that is conducive for
positioning the mounting plates 4 and 5 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 mounting
plates 4 and 5 to the interior surface of a skull. In the anchoring
position, the mounting plates 4 and 5 may be disposed transverse to
each other and form a generally crisscross or "X" shape or
configuration, as best seen in FIG. 7C.
[0042] Mounting plate 5 includes one or more barbs, e.g., barbs 20c
and 20d, disposed on a top surface 30 thereof. As described above
with respect to barbs 20a and 20b, barbs 20c and 20d may reside in
corresponding recesses 21c and 21d, respectively, see FIGS.
5-7C).
[0043] To facilitate positioning the mounting plates 4 and 5 inside
the occiput, a bottom surface 28 of the mounting plate 5 includes a
pair of indents 25a and 25b that are configured to releasably
engage the barbs 20a and 20b (FIG. 7D); the indents 25a and 25b are
shown engaged with the barbs 20a and 20b, respectively and, as a
result thereof, are not explicitly shown. In the "nested" position,
the mounting plate 5 and the mounting plate 4 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 mounting plate 5, which can be seated or anchored
into the occiput by pulling the nested mounting plates 4 and 5 so
that the barbs 20c and 20d on the mounting plate 5 "dig" into the
inside of the occiput. Subsequently, the mounting plate 4 can be
deployed to the final (cross) position (FIG. 7C) using the slot 17
in the end of the threaded bolt. More particularly, the operable
end of a screwdriver may be utilized to engage the slot 17 and,
subsequently, turn the mounting plate 4 that disengages the barbs
20a and 20b from the respective indents 25a and 25b. The barbs 20a
and 20b on the mounting plate 4 may then be brought into contact
with the inside of the occiput, thus, fixing both mounting plates 4
and 5 in place.
[0044] To facilitate anchoring the mounting plates 4 and 5 into the
interior surface of a skull, a bottom surface 28 of the mounting
plate 5 includes a notched portion 24 that is configured to receive
and/or mate with a portion, e.g., a corresponding notched portion
26 disposed on the top surface 10, of the mounting plate 4 (FIGS.
7B and 7D). In the anchored position, the notched portions 24 and
26 enable the top surface 10 of the mounting plate and top surface
30 of the mounting plate 5 to be flush with each other, as best
seen in FIG. 7D; this provides a substantially uniform contact
surface between the mounting plates 4 and 5 and the interior
surface of the skull. This substantially uniform contact surface
facilitates positioning the barbs 20a-20d adjacent to the interior
surface of the skull, which, in turn, ensures that the barbs
20a-20d properly engage the interior surface of skull. As can be
appreciated, having all the barbs 20a-20d properly engaged to the
interior surface of the skull reduces and/or eliminates the
likelihood of inadvertent movement of the mounting plates 4 and 5
after the occipital fixation assembly 2a has been affixed to the
interior surface of the skull.
[0045] 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.
[0046] Mounting plate 4 is positioned through the aperture created
within the sinus cavity adjacent the occiput. Thereafter, coupling
member 6 is positioned about the threaded post 14a (see FIG. 1 in
combination with FIG. 3). In particular, once the physician creates
the desired opening the patient's skull, one end of the mounting
plate 4 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 mounting plate 4 is moved
in a generally opposing direction such that the entire mounting
plate 4 is disposed beneath the surface of the skull (i.e. on the
inside). Once positioned, the threaded post 14a extends 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 mounting plate 4.
[0047] The fixation nut 8 including the washer 54 is positioned
about the threaded post 14a and over the base 36 of coupling member
6. For illustrative purposes, the fixation nut 8 including washer
54 is shown engaged with the coupling member 6. Subsequently, the
fixation nut 8 is rotated in a predetermined direction, e.g., a
clockwise direction, about the threaded post 14a. In one particular
embodiment, a screwdriver (or other suitable device) is utilized to
engage the slot 17 to facilitate rotation the mounting plate 4
and/or fixation nut 8. Rotation of the fixation nut 8 about the
threaded post 14b causes the coupling member 6 and the mounting
plate 4 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 member 6 (with barbs 20e-20g) and
mounting plate 4 (with barbs 20a-20b) by threading the fixation nut
8 over the threaded post 14a and tightening to the specified
torque.
[0048] In some surgical scenarios, the occiput is "sandwiched"
between the surgical rod coupling member 6 (with barbs 20e-20g) and
mounting plates 4 and 5 (with barbs 20a-20d) by threading the
fixation nut 8 over the threaded post 14a and tightening to the
specified torque.
[0049] Thereafter, the surgical rod "R" is coupled to the offset
extension 34 of the coupling member 6 and secured to the coupling
member 6 via the set screw 42.
[0050] As can be appreciated, the combination of the unique
mounting plate 4 having the threaded post 14a configured to couple
to the coupling member 6 reduces and/or eliminates the likelihood
of the occipital fixation assembly 2 inadvertently pulling out from
the occiput, which, in turn, reduces the risk for cerebellar
injury. Moreover, anchoring the barbs 20a-20b and the barbs 20e-20g
into the interior and exterior surfaces, respectively, of the skull
diminishes the likelihood of inadvertent rotation of mounting plate
4 and coupling member 6 after the surgical rod "R" has been
attached to the occipital fixation assembly and/or the spine.
[0051] With reference to FIGS. 8A and 8B, an alternate embodiment
of an elongated post is designated elongated post 14b. In this
embodiment, the elongated post 14b is provided without the slot 17.
More particularly, unlike the elongated post 14a, elongated post
14b includes a plurality of non-continuous threads 16b extending
partially along an outer circumferential surface of the elongated
post 14b. A proximal end of the elongated post 14b includes a
threaded aperture 19 that extends into the threaded post 14b (FIG.
8A). The threaded aperture 19 is configured to receive one end of a
surgical device, e.g., wrench assembly 80, for positioning and
turning the fixation nut 8 about the threaded post 14b (FIGS.
11A-11D). A non-threaded aperture 21 extends traverse to the
threaded aperture 19 and is configured to receive one end of a
surgical device, e.g., a forceps 60, for grasping the threaded post
14b and maintaining the mounting plate 4a in a non-rotatable state
when the fixation nut 8 is rotated about the elongated post 14b
(FIGS. 9-11B).
[0052] With reference to FIGS. 9-11D, system 100 includes a forceps
60 (FIGS. 9 and 11A-11C), a wrench assembly 80 (FIGS. 11A-11D) and
the occipital fixation assembly 2b (FIG. 11D) that includes the
mounting plate 4a with the threaded post 14b (FIG. 10).
[0053] Forceps 60 is configured to grasp a portion of the threaded
post 14b (as best seen in FIG. 10). More particularly, the forceps
60 may be utilized to grasp the threaded post 14b to facilitate
positioning the mounting plate 4 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, forceps 60 may be
utilized to grasp the threaded post 14b to maintain the mounting
plate 4a in a non-rotatable state when the fixation nut 8 is
rotated about the elongated post 14b. Forceps 60 includes first and
second shafts 61 and 62. Each shaft 61 and 62 has a respective jaw
member 63 and 64 extending from a distal end thereof and a handle
65 and 66 disposed at a proximal end thereof for effecting movement
of the jaw members 63 and 64 relative to one another about a pivot
67. The jaw members 63 and 64 are movable from a first position
(FIG. 11C) wherein the jaw members 63 and 64 are disposed in spaced
relation relative to one another to a second position wherein the
jaw members 63 and 64 cooperate to grasp the threaded post (FIGS.
9-11B).
[0054] Each of the jaw members 63 and 64 includes a respective
inner facing surface 69 and 68 (FIGS. 10 and 11C) having a
respective proximal end 70 and 71 (FIG. 9) and a respective distal
end 72 and 73 that is offset from the proximal end 70 and 71 (FIG.
10). In the closed configuration, the distal ends 72 and 73 of the
inner facing surfaces 69 and 68 remain spaced-apart from each other
to facilitate grasping the threaded post therebetween (FIGS.
9-11A).
[0055] The distal ends 72 and 73 of the jaw members 63 and 64
include a protrusion 74 and 75 (FIGS. 10 and 11C) thereon that is
configured to releasably engage the non-threaded aperture 21 on the
threaded post 14b.
[0056] A ratchet mechanism 90 may be operably coupled to the shafts
61 and 62 adjacent the handles 65 and 66 and is configured to
maintain the jaw members 63 and 64 in one or more positions. More
particularly, each shaft 61 and 62 includes a respective ratchet
component 90a and 90b each having a plurality of ratchet teeth that
are configured to matingly engage with one another.
[0057] As can be appreciated, in the instance where the occipital
fixation assembly 2 includes a mounting plate 4 with a threaded
post 14a, the inner facing surfaces 69 and 68 of the forceps 60 may
be provided without the protrusions 74 and 75. For example, the
inner facing surfaces 69 and 68 of forceps 60 may include one or
more slots or grooves that are configured to matingly engage with
the plurality of threads 16a on the threaded post 14a.
[0058] Wrench assembly 80 is configured to rotate the fixation nut
8 about the threaded post 14b (FIGS. 11B and 11C). Wrench assembly
80 includes a coupling member 81 that is configured to threadably
engage the threaded aperture 19 on the threaded post 14b of the
mounting plate 4 (FIGS. 11A-11C). Wrench assembly 80 includes a
wrench head member 82 that is selectively and coaxially engageable
with the coupling member 81 (FIGS. 11A-11C).
[0059] The coupling member 81 includes a generally elongated shaft
83 (FIGS. 11A and 11D) having a threaded distal end 84 (FIGS. 11A
and 11C), and proximal end 85 that is configured to rotate the
threaded distal end 84 into the threaded aperture 19 of the
threaded post 14b of the mounting plate 4a for securement of the
coupling member to the mounting plate 4.
[0060] A portion 86 (FIGS. 11A and 11D) of the coupling member 81
proximate to the threaded distal end 84 has an outer diameter that
is slightly smaller than an inner diameter of the fixation nut 8,
so that the fixation nut 8 can slide over portion 86. The portion
86 is configured to facilitate positioning the fixation nut 8 on
the threaded post 14b of the mounting plate 4a. More particularly,
the portion 86 is configured to guide the fixation nut 8 into
position on the threaded post 14b. In one particular embodiment,
the elongated extension 50 of the fixation nut 8 is configured to
slide over the portion 86 and guide the fixation nut 8 into
position on the threaded post 14b
[0061] The proximal end 85 of the coupling member 81 is
complementary shaped to receive an open end of a turn-key 87. In
the illustrated embodiment, the proximal end 85 and the open end of
the turn-key 87 include a hexagonal shape. The turn-key 87 is
configured to facilitate rotation of the threaded distal end 84
into the threaded aperture 19 on the threaded post 14b of the
mounting plate 4a.
[0062] In the embodiment illustrated in FIGS. 11A-11D, a portion 88
of the shaft 81 proximate to the threaded distal end 84 is textured
or otherwise treated to provide an additional gripping surface for
a user, or to provide mechanical interface for maintaining the
turn-key 87 at the proximal end 85.
[0063] The wrench head member 82 is configured to releasably engage
the fixation nut 8 and rotate the fixation nut 8 about the threaded
post 14b of the mounting plate 4a. To this end, the wrench head
member 82 is complementary shaped to receive and turn the fixation
nut 8. In the embodiment illustrated in FIGS. 11A-11D, a proximal
end 89 of the wrench head member 82 is textured or otherwise
treated to facilitate rotation of the wrench member head. As can be
appreciated, the wrench head member 82 may be utilized to rotate
the fixation nut 8 about the threaded post 14a.
[0064] Operation of the system 100 including the occipital fixation
assembly 2b including the mounting plate 4a with the threaded post
14b is described in terms of use of a method for attaching the
occipital fixation assembly 2b for subsequent attachment of a
surgical rod "R" thereto.
[0065] 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.
[0066] The forceps 60 may be utilized for grasping the threaded
post 14b to insert the mounting plate 4a through the aperture
created within the sinus cavity and to temporarily hold the
threaded post 14b in place (FIGS. 9-11B). Thereafter, coupling
member 6 is positioned about the threaded post 14b.
[0067] The fixation nut 8 including the washer 54 is positioned
about the threaded post 14b and over the base 36 of coupling member
6. To facilitate positioning the fixation nut 8 about the threaded
post 14b, the coupling member 81 of the wrench assembly 80 may be
coupled to the threaded post 14b, see FIG. 11A where the coupling
member 81 is shown adjacent the threaded post 14b just before
coupling the coupling member 81 to the threaded post 14b. The
turn-key may be utilized to facilitate turning the coupling member
81 about the threaded post 14b.
[0068] Subsequently, the fixation nut 8 is rotated in a
predetermined direction, e.g., a clockwise direction, about the
threaded post 14b. To facilitate rotating the fixation nut 8 about
the threaded post 14b, the wrench head member 82 may be positioned
coaxially about the coupling member 81 and into engagement with the
fixation nut 8 (FIG. 11B). It should be noted that once the
fixation nut 8 has been engaged to the threaded post 14b, the
forceps 60 may be removed from engagement with the threaded post
14b (FIG. 11C). It is further contemplated that the threaded
engagement between to threaded distal end 84 and the threaded
aperture 19 may be opposed to the threaded engagement between
fixation nut 8 and post 14b (i.e., one may engage in a clockwise
direction and the other in a counterclockwise direction) so that as
the fixation nut 8 is tightened the coupling member 6 does not
loosen from the threaded post 14b. In this manner, even after the
forceps 60 have been removed, control may be exerted over the
threaded post 14b as the fixation nut 8 is tightened.
[0069] The wrench head member 82 is rotated about the fixation nut
8, which, in turn, rotates the fixation nut 8 about the threaded
post 14b, this in turn, causes the coupling member 6 and the
mounting plate 4a to move toward one another and into secured
engagement with an interior and exterior surface, respectively, of
the skull of a patient.
[0070] In one surgical scenario, after the coupling member 6 and
the mounting plate 4a are moved into secured engagement with the
interior and exterior surface of the skull, the wrench assembly 80
is removed from the occipital fixation assembly 2 (FIG. 11D).
Thereafter, the surgical rod "R" is coupled to the offset extension
34 of the coupling member 6 and secured to the coupling member 6
via the set screw 42.
[0071] 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 the slot 38 of the offset extension 34 includes a taper
locking mechanism for capturing the surgical rod "R" such that a
set screw 42 is not required.
[0072] In yet another embodiment, the slot 38 of the offset
extension 34 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 the occipital fixation
assembly 2.
[0073] In yet another embodiment, a fixation nut may be integrally
formed with a coupling member. More particularly, and with
reference to FIGS. 12A and 12B, a coupling member 6A and a fixation
nut 8A are integrally formed with one another via one or more
suitable coupling methods, e.g., soldering, brazing or welding. In
this instance, the fixation nut 8A is swaged, but rotatable, to the
coupling member 8A along with a washer making it an integral
assembly. In this instance, the coupling member 6A including the
fixation nut 8A are positioned about the threaded post 14b
simultaneously.
[0074] 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.
* * * * *