U.S. patent application number 17/372995 was filed with the patent office on 2022-01-06 for interbody implant with concave profiled nose.
The applicant listed for this patent is Advance Research System, LLC. Invention is credited to Hamid R. Abbasi.
Application Number | 20220000630 17/372995 |
Document ID | / |
Family ID | |
Filed Date | 2022-01-06 |
United States Patent
Application |
20220000630 |
Kind Code |
A1 |
Abbasi; Hamid R. |
January 6, 2022 |
INTERBODY IMPLANT WITH CONCAVE PROFILED NOSE
Abstract
An interbody implant and inserter tool for spinal fusion. The
interbody implant includes a cage portion and a nose portion. In
some embodiments, an outer surface of the nose portion defines at
least a first concave profile in a first direction, and may define
a second concave profile in a second direction, the second
direction being perpendicular to the first direction. The outer
surface may also define an oblong cross-section normal to a nose
axis. The oblong cross-section may be axisymmetric or continuously
curved (or both) about the nose axis. The concave profile(s) enable
easier initial insertion of for more precisely locating the
interbody implant, so that the greater insertion forces required
during implantation do not occur until the interbody implant is
securely and accurately placed.
Inventors: |
Abbasi; Hamid R.; (Edina,
MN) |
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Applicant: |
Name |
City |
State |
Country |
Type |
Advance Research System, LLC |
Edina |
MN |
US |
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Appl. No.: |
17/372995 |
Filed: |
July 12, 2021 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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16469569 |
Jun 13, 2019 |
11058551 |
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PCT/US2017/066641 |
Dec 15, 2017 |
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17372995 |
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62524079 |
Jun 23, 2017 |
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62435598 |
Dec 16, 2016 |
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International
Class: |
A61F 2/44 20060101
A61F002/44; A61F 2/46 20060101 A61F002/46 |
Claims
1. An interbody implant, comprising: a cage portion defining a cage
axis that passes through a proximal portion and a distal portion
thereof; and a nose portion extending in a distal direction from
the distal portion of the cage portion, the nose portion defining a
nose axis that is concentric with the cage axis, the nose axis
extending in the distal direction from the cage portion through a
distal extremity of the nose portion, the nose portion defining an
outer surface about the nose axis that tapers toward the nose axis
in the distal direction, the outer surface defining a first concave
profile in a first direction from the nose axis, the first
direction being perpendicular to the nose axis, the nose portion
defining a through-passage concentric about the nose axis.
2.-7. (canceled)
8. The interbody implant of claim 1, wherein the outer surface of
the nose portion defines a second concave profile in a second
direction from the nose axis, the second direction being
perpendicular to the first direction at any point along the nose
axis.
9. The interbody implant of claim 8, wherein the outer surface of
the nose portion defines an oblong cross-section at a cross-section
plane that intersects and is orthogonal to the nose axis, the
oblong cross section defining a major dimension and a minor
dimension, the minor dimension being perpendicular to the major
dimension.
10. The interbody implant of claim 9, wherein the oblong
cross-section is continuously curved.
11. The interbody implant of claim 10, wherein the oblong
cross-section is elliptical.
12. The interbody implant of claim 9, wherein a ratio of the major
dimension to the minor dimension is in a range of 1.05 to 1.20
inclusive.
13.-14. (canceled)
15. The interbody implant of claim 9, wherein the cross-section
plane intersects the nose axis at a midpoint that is equidistant
between the base plane and the distal extremity.
16.-19. (canceled)
20. The interbody implant of claim 1, wherein the nose axis is
linear.
21. The interbody implant of claim 1, wherein: the proximal portion
of the cage portion includes a proximal wall and the distal portion
of the cage portion includes a distal wall; the proximal wall and
the distal wall are separated by opposing side walls; the proximal
wall, distal wall, and opposing side walls define a superior edge
surface and an inferior edge surface; the cage axis passes through
a center of the proximal wall and a center of the distal wall and
the distal wall defines an inlet to the through-passage of the nose
portion that is concentric with the nose axis.
22. The interbody implant of claim 21, wherein at least one of the
superior edge surface and the inferior edge surface defines a
plurality of gripping facets.
23. The interbody implant of claim 22, wherein each of the
plurality of gripping facets defines a ridge that extends along a
ridge line, the ridge line extending proximally at a swept angle
relative to the cage axis, the swept angle defining an acute
angle.
24. The interbody implant of claim 21, wherein each of the opposing
side walls defines a side graft window that passes
therethrough.
25. The interbody implant of claim 24, wherein the side graft
window defines an elongate slot.
26. The interbody implant of claim 25, wherein the elongate slot
extends substantially parallel to the cage axis.
27. The interbody implant of claim 21, wherein the proximal wall
defines an exterior recess and a through-hole, the through-hole
being defined at a distal face of the exterior recess and
concentric about the cage axis.
28. The interbody implant of claim 27, wherein the exterior recess
is polygonal.
29. (canceled)
30. The interbody implant of claim 21, wherein at least one of the
superior edge surface and the inferior edge surface defines a
convex profile that is arcuate about a lateral axis, the lateral
axis being perpendicular to the cage axis and passing through the
opposing side walls.
31. The interbody implant of claim 1, wherein the nose portion
extends from a base plane proximate the distal portion of the cage
portion, the base plane being orthogonal to the nose axis.
32. The interbody implant of claim 1, wherein the outer surface of
the nose portion is axisymmetric about the nose axis.
33. The interbody implant of claim 1, wherein the interbody implant
is titanium.
34.-37. (canceled)
Description
RELATED APPLICATIONS
[0001] The present application is a continuation of U.S. patent
application Ser. No. 16/469,569, filed Jun. 13, 2019, which is a
National Phase entry of PCT Application No. PCT/US2017/066641,
filed Dec. 15, 2017, which claims the benefit of U.S. Provisional
Patent Application No. 62/435,598, filed Dec. 16, 2016, and of U.S.
Provisional Patent Application No. 62/524,079, filed Jun. 23, 2017,
the disclosures of which are hereby incorporated by reference
herein in their entirety.
FIELD OF THE DISCLOSURE
[0002] The disclosure relates generally to interbody implants for
spinal fusion, and more specifically to spinal cage implants having
insertion tips.
BACKGROUND OF THE DISCLOSURE
[0003] Interbody implants are utilized for spinal fusion
(arthrodesis) to restrict movement between vertebrae. The implants
support and immobilize adjacent vertebrae while new bone tissue
grow between the vertebrae.
[0004] Surgically implanting the interbody implants requires
placement of the implant at desired locations and orientations, and
in some procedures require substantial manipulation forces (thrust
and torque) to accomplish insertion of the implant. Many interbody
implants include a cage through which the new bone tissue can grow
with a nose portion that aids in the insertion. However, forces
associated with the implantation of these interbody implants can be
prohibitive, resulting in high stresses on the vertebrae during
implantation.
[0005] An interbody implant and implant system that facilitates
implantation of the cage while reducing the manipulation forces
associated with implantation would be welcomed.
SUMMARY OF THE DISCLOSURE
[0006] Various embodiments of the disclosed cage-type interbody
implant facilitates insertion of the implant at reduced forces
relative to conventional cage-type interbody implants. The profile
of a nose portion of the interbody implant provides a small
cross-sectional area proximate the distal end of the nose portion
that is readily inserted into gaps within the spine structure. The
outer surface of the nose portion slopes more gradually at the
distal locations of the nose portion than at the proximal or base
portions of the nose. This enables the nose portion to become
firmly yet easily aligned within the desired entry location between
adjacent vertebrae before the maximum manipulation forces are
applied for final insertion.
[0007] In some embodiments, the outer surface nose portion defines
a cross-section perpendicular to a nose axis, the cross-sections
defining rounded surfaces that substantially reduce or eliminate
adjacent flats or straight portions and associated transition
corners therebetween. Such flats and transition corners are common
in conventional interbody implants, and can inhibit rotational
manipulation of the implant during insertion. The rounded surfaces
enable easier rotation and reduce the torsional manipulation forces
of the interbody implant. The ease of rotation and reduced
torsional manipulation forces are particularly notable during
initial alignment and insertion of the nose portion, where only the
distal portion of the nose having a small insertion cross-section
is engaged with the targeted vertebrae.
[0008] In some embodiments, an implant system facilitates guidance
of the interbody implant to the desired location in the spine and
at a desired orientation. An inserter is configured for rotational
and thrust manipulation, and may include a guide wire. The
interbody implant may be configured to accommodate the guide wire,
so that the implant system more accurately guides the interbody
implant to the target location.
[0009] Structurally, various embodiments of the disclosure include
an interbody implant comprising a cage portion defining a cage axis
that passes through a proximal portion and a distal portion
thereof, and a nose portion extending in a distal direction from
the distal portion of the cage portion, the nose portion defining a
nose axis that is concentric with the cage axis, the nose axis
extending in the distal direction from the cage portion through a
distal extremity of the nose portion, the nose portion defining an
outer surface about the nose axis that tapers toward the nose axis
in the distal direction. The nose axis may be linear. In some
embodiments, the interbody implant is titanium.
[0010] In some embodiments, the outer surface defines a first
concave profile in a first direction from the nose axis, the first
direction being perpendicular to the nose axis. In some
embodiments, the nose portion defines a through-passage concentric
about the nose axis, wherein: the cage portion and the nose portion
define a through-passage concentric about the nose axis and the
cage axis, the through-passage defining a minimum diameter; and at
least one of the cage portion and the nose portion defines a first
slot that extends from the through-passage through an exterior
surface of the interbody implant, the first slot being in fluid
communication with the through-passage, the first slot being
coplanar with at least one of the nose axis and the cage axis and
defining a gap dimension that is less than the minimum diameter of
the through-passage.
[0011] In some embodiments, the first concave profile and the nose
axis are co-planar. The second concave profile and the nose axis
may also be co-planar. In some embodiments, the first concave
profile is different from the second concave profile. Also, the
first concave profile may define a first concavity and the second
concave profile a second concavity, the first concavity being
greater than or less than the second concavity.
[0012] In some embodiments, a second slot extends through an outer
surface of the proximal portion of the cage portion, the second
slot being coplanar with the cage axis. The first slot and the
second slot may be coplanar. In some embodiments, a rib bridges the
first slot proximate the through passage. The rib may be disposed
at one of the distal portion of the cage portion and the distal
extremity of the nose portion.
[0013] In some embodiments, the outer surface of the nose portion
defines a second concave profile in a second direction from the
nose axis, the second direction being perpendicular to the first
direction at any point along the nose axis. The outer surface of
the nose portion may define an oblong cross-section at a
cross-section plane that intersects and is orthogonal to the nose
axis, the oblong cross section defining a major dimension and a
minor dimension, the minor dimension being perpendicular to the
major dimension. In some embodiments, the oblong cross-section is
continuously curved. In one example, the oblong cross-section is
elliptical. A ratio of the major dimension to the minor dimension
is in a range of: 1.05 to 1.20 inclusive; 1.05 to 1.15
inclusive;
1.07 to 1.12 inclusive. In some embodiments, the cross-section
plane intersects the nose axis at a midpoint that is equidistant
between the base plane and the distal extremity.
[0014] In some embodiments of the disclosure, the proximal portion
of the cage portion includes a proximal wall and the distal portion
of the cage portion includes a distal wall. The proximal wall and
the distal wall are separated by opposing side walls. The proximal
wall, distal wall, and opposing side walls define a superior edge
surface and an inferior edge surface. The cage axis may pass
through a center of the proximal wall and a center of the distal
wall. In some embodiments, at least one of the superior edge
surface and the inferior edge surface defines a plurality of
gripping facets. Each of the plurality of gripping facets may
define a ridge that extends along a ridge line, the ridge line
extending proximally at a swept angle relative to the cage axis,
the swept angle defining an acute angle. Each of the opposing side
walls defines a side graft window that passes therethrough. In some
embodiments, the side graft window defines an elongate slot. The
elongate slot may extend substantially parallel to the cage axis.
In some embodiments, the proximal wall defines an exterior recess
and a through-hole, the through-hole being defined at a distal face
of the exterior recess and concentric about the cage axis. The
exterior recess may be polygonal.
[0015] In some embodiments, the nose portion and distal wall define
a through-passage concentric about the nose axis, the nose axis
being concentric with the cage axis. At least one of the superior
edge surface and the inferior edge surface defines a convex profile
that is arcuate about a lateral axis, the lateral axis being
perpendicular to the cage axis and passing through the opposing
side walls. In some embodiments, the nose portion extends from a
base plane proximate the distal portion of the cage portion, the
base plane being orthogonal to the nose axis. The outer surface of
the nose portion may be axisymmetric about the nose axis.
[0016] In various embodiments of the disclosure, an interbody
implant for treatment of a spine comprises an interbody implant
including a nose portion defining a nose axis and having a distal
extremity and a mid portion. The distal extremity defines a first
cross-section that is orthogonal to the nose axis, the nose portion
including an outer surface that is axisymmetric about the nose
axis, the outer surface defining a first slope at the distal
extremity that is coplanar with the nose axis, the first slope
defining a first acute angle relative to the nose axis. The mid
portion defines a second cross-section that is orthogonal to the
nose axis, the outer surface defining a second slope at the mid
portion that is coplanar with the first slope, the second slope
defining a second acute angle relative to the nose axis. The first
cross-section is smaller than the second cross-section, and the
first acute angle is smaller than the second acute angle. In some
embodiments, each of the first cross-section and the second
cross-section defines a shape that is one of a circular shape and
an oblong shape.
[0017] In various embodiments of the disclosure, a method for
implanting an interbody implant is disclosed, comprising providing
a kit including the interbody implant and a set of instructions on
a tangible, non-transitory medium for implanting the interbody
implant, the instructions including:
guiding the interbody implant for implantation at a target
location; inserting the distal extremity of the nose portion of the
interbody implant for implantation into the target location; and
initially thrusting the mid portion of the nose portion for
penetration of the target location, wherein the first cross-section
being smaller than the second cross-section, the first acute angle
being smaller than the second acute angle, and the shape of the
first cross-section, combine to make the step of insertion and the
step of initially thrusting the interbody implant easier than for
state of the art fusion cages.
[0018] In some embodiments of the method, the instructions include
the step of using a guide wire in the step of guiding the interbody
implant to the target location. In some embodiments of the method,
the instructions include the step of rotating the interbody implant
about the nose axis so that an edge surface defining a convex
baseline of a cage portion of the interbody implant is arranged for
contact with a vertebral end plate proximate the target
location.
BRIEF DESCRIPTION OF THE DRAWINGS
[0019] FIGS. 1 through 3 are perspective views of an interbody
implant according to an embodiment of the disclosure;
[0020] FIG. 4 is a plan view of the interbody implant of FIG.
1;
[0021] FIG. 5 is an elevational view of a proximal end of the
interbody implant of FIG. 1;
[0022] FIG. 6 is an elevational view of a lateral side of the
interbody implant of FIG. 1;
[0023] FIG. 7 is an elevational view of a distal end of the
interbody implant of FIG. 1;
[0024] FIG. 8 is a sectional view along line VIII-VIII of FIG. 4
according to an embodiment of the disclosure;
[0025] FIG. 9 is a section view along line IX-IX of FIG. 6
according to an embodiment of the disclosure;
[0026] FIG. 10 is a sectional view along line X-X of FIG. 6
according to an embodiment of the disclosure;
[0027] FIG. 11 is an example of an elliptical cross-section
according to an embodiment of the disclosure;
[0028] FIG. 12 is an example of an oval cross-section according to
an embodiment of the disclosure;
[0029] FIG. 13 is an example of an obround cross-section according
to an embodiment of the disclosure;
[0030] FIG. 14 is a perspective view of an inserter according to an
embodiment of the disclosure;
[0031] FIG. 15 is a perspective view of the inserter of FIG. 14
being aligned with the interbody implant of FIG. 1 for
assembly;
[0032] FIG. 16 is a perspective view of the inserter and interbody
implant of FIG. 15 in assembly;
[0033] FIG. 17 is a perspective view of the inserter of an inserter
having a channeled knob, with interbody implant of FIG. 1 in
assembly according to an embodiment of the disclosure;
[0034] FIG. 18 is a proximal end view of the inserter with the
channeled knob of FIG. 17;
[0035] FIG. 19 is an enlarged, partial side view of a guide wire
recessed within a channel of the channeled knob of FIG. 17;
[0036] FIG. 20 is a plan view of a tray for a kit that includes
caddies with a variety of interbody implants according to an
embodiment of the disclosure;
[0037] FIG. 21 is a plan view of an instrument tray for a kit
according to an embodiment of the disclosure;
[0038] FIG. 22 is a rear perspective view of an interbody implant
having convex superior and inferior surfaces according to an
embodiment of the disclosure;
[0039] FIG. 23 is a front perspective view of the interbody implant
of FIG. 22;
[0040] FIG. 24 is a plan view of the interbody implant of FIG.
22;
[0041] FIG. 25 is a side elevational view of the interbody implant
of FIG. 22;
[0042] FIG. 26 is a rear perspective view of an interbody implant
having a slotted nose portion according to an embodiment of the
disclosure;
[0043] FIG. 27 is a plan view of the interbody implant of FIG.
26;
[0044] FIG. 28 is a sectional view of the interbody implant along
plane XXVIII-XXVIII of FIG. 27;
[0045] FIG. 29 is a rear perspective view of an interbody implant
having a slotted nose portion and a slotted rear wall portion
according to an embodiment of the disclosure;
[0046] FIG. 30 is a plan view of the interbody implant of FIG.
29;
[0047] FIG. 31 is a sectional view of the interbody implant along
plane XXXI-XXXI of FIG. 30;
[0048] FIG. 32 is a rear perspective view of an interbody implant
having a slotted nose portion and a partially slotted rear wall
portion according to an embodiment of the disclosure;
[0049] FIG. 33 is a plan view of the interbody implant of FIG.
32;
[0050] FIG. 34 is a sectional view of the interbody implant along
plane XXXIV-XXXIV of FIG. 33;
[0051] FIG. 35 is a rear perspective view of an interbody implant
having a slotted nose portion and a partially slotted rear wall
portion according to an embodiment of the disclosure;
[0052] FIG. 36 is a plan view of the interbody implant of FIG. 35;
and
[0053] FIG. 37 is a sectional view of the interbody implant along
plane XXXVII-XXXVII of FIG. 36.
DETAILED DESCRIPTION
[0054] Referring to FIGS. 1 through 9, an interbody implant 30a is
depicted according to an embodiment of the disclosure. The
interbody implant 30a includes a cage portion 32 and a nose portion
34. The cage portion 32 includes a proximal portion 41 that may
include a proximal wall 42 and a distal portion 43 that may include
a distal wall 44. In the depicted embodiment, the proximal wall 42
and the distal wall 44 are separated by opposing side walls 46 and
48. The proximal wall 42, distal wall 44, and opposing side walls
46 and 48 cooperate to define opposed edge surfaces 52 and 54. The
cage portion 32 defines a cage axis 36 that passes through a center
56 of the proximal wall 42 and a center 58 of the distal wall 44
(FIG. 3). In some embodiments, one or both of the opposed edge
surfaces 52, 54 define a plurality of gripping facets 57a extending
therefrom.
[0055] The nose portion 34 extends in a distal direction 60 from
the distal portion 43, the nose portion 34 extending from a base
plane 62 (FIG. 4) proximate the distal wall 44 of the cage portion
32 to a distal extremity 64. The base plane 62 and the distal
extremity 64 are separated by a mid portion 65 of the nose portion
34. The nose portion 34 defines a nose axis 38 that extends from
the center 58 of the distal wall 44 through a center 66 of the
distal extremity 64. The nose portion 34 further defines an outer
surface 70 about the nose axis 38 that tapers toward the nose axis
38 in the distal direction 60. In the depicted embodiment, the nose
portion 34 defines a through-passage 68 that is concentric about
the nose axis 38. Herein, the base plane 62 passes through a
distal-most intersection point 71 of the cage portion 32 and the
outer surface 70 of the nose portion 34 and is orthogonal to the
nose axis 38 (FIG. 8).
[0056] In the depicted embodiment, the outer surface 70 defines a
first concave profile 72 in a first direction 74 from the from the
nose axis 38, the first direction 74 being perpendicular to the
nose axis 38. The outer surface 70 of the nose portion 34 may also
define a second concave profile 76 in a second direction 78 from
the nose axis 38 (FIG. 2), the second direction 78 being
perpendicular to the first direction 74 at any point along the nose
axis 38. In FIGS. 8 and 9, concavities of the first and second
concave profiles 72 and 76 are illustrated by contrasting each with
a respective straight line 92 and 94 that passes through the end
points of the respective first and second concave profiles 72 and
76. Herein, a first "concavity" of the first concave profile is the
maximum dimension between the concave profile 72 and the straight
line 92 in a direction perpendicular to the straight line 92. A
second "concavity" of the second concave profile is the maximum
dimension between the concave profile 76 and the straight line 94
in a direction perpendicular to the straight line 94. The first and
second concave profiles 72 and 76 may define different profiles and
different concavities.
[0057] A characteristic of the concave profiles 72 and 76 is that
the slope of the nose portion 34 continuously and monotonically
increases in the proximal direction 61, so that not only are the
cross-sections orthogonal to the nose axis 38 smaller at the distal
extremity 64, the slope defined at the distal extremity 64 is
smaller than the slopes defined along the mid portion 65 of the
nose portion 34. This characteristic is illustrated for the concave
profile 76 of FIG. 9, but applies equally to the concave profile 72
of FIG. 8, as well the concave profile of the nose portion 34
defined at any angular orientation relative to the nose axis 38. In
FIG. 9, a slope line 96 is depicted that is representative of the
slope of the concave profile 76 at the distal extremity 64, and a
slope line 98 is depicted that is representative of the slope of
the concave profile 76 at an arbitrary point on the mid portion 65
of the nose portion 34. The slope line 96 at the distal extremity
64 intercepts the nose axis 38 at an acute angle .alpha.1, and the
slope line 98 at the mid portion 65 intercepts the nose axis 38 at
an acute angle .alpha.2. The slope line 96 at the distal extremity
64 intercepts the nose axis 38 at a shallower acute angle than does
the slope line 98 at the mid portion 65. That is, acute angle
.alpha.1 is less than acute angle .alpha.2.
[0058] Functionally, the combination of the smaller cross-sections
and smaller acute angles proximate the distal extremity 64 reduces
the forces required for the insertion and initial thrusting of the
interbody implant 30 during initial location and placement,
relative to state of the art fusion cages that have blunted noses
of comparatively larger cross-section. The reduced force
requirement reduces the difficulty of the insertion and initial
thrusting to improve the accuracy of the placement of the interbody
implant 30, and reduces or avoids the trauma associated with
adjustment or resetting of the implant due to initial misplacement.
The circular or oblong shape of the nose cross-sections also makes
rotation of the interbody implant 30 easier than with conventional
interbody implants that have a square or a rounded-corner square
cross-section, thus making rotational orientation of the interbody
implant 30 after initial placement easier and less traumatic than
rotational orientation of conventional interbody implants.
[0059] In the depicted embodiment, the cage and nose axes 36 and 38
of the interbody implant 30a are linear. Because the nose axis 38
is linear, the nose axis 38 is co-planar with both the first
concave profile 72 and the second concave profile 76. However, the
cage and nose axes 36 and 38 are not so limited. That is, interbody
implants are contemplated that have curved cages and nose portions,
as disclosed, for example, in U.S. Patent Application Publication
No. 2006/0167548 to Jackson. In embodiments where the cage portion
or nose portion or both are curved (not depicted herein), the cage
and nose axes, being defined by the respective cage and nose
portions, are also curved. For a curved nose axis, one of the
concave profiles may be co-planar with the curved nose axis, but
not both the concave profiles.
[0060] Herein, several embodiments of interbody implants are
disclosed. The interbody implants are referred to collectively and
generically with reference character 30, and specifically and
individually with reference character 30 followed by a letter
suffix (i.e., interbody implant 30a, discussed above). Likewise,
the gripping facets are referred to collectively and generically
with reference character 57, and specifically and individually with
reference character 57 followed by a letter suffix (i.e., gripping
facets 57a).
[0061] Referring to FIGS. 10 through 13, cross-sectional profiles
100 and 100a-100c of the outer surface 70 of the nose portion 34 in
a cross-section plane 102 that intersects and is orthogonal to the
nose axis 38 are depicted according to embodiments of the
disclosure. In FIG. 10, the cross-section plane 102 intersects the
nose axis 38 at a midpoint 105 (cross-section plane 102 and
midpoint 105 both depicted in FIG. 8) along the nose axis 38 that
is equidistant between the base plane 62 and the distal extremity
64. Generally, the outer surface 70 of the nose portion 34 includes
rounded surfaces having cross-sections that defined little or no
adjacent straight portions that require corner transitions. Such
rounded surfaces may define a circular cross-section (not depicted)
or oblong cross-sections 104. Herein, an "oblong" cross section is
one that defines a maximum or major dimension 106 and a minor or
minimum dimension 108, the minor dimension 108 being perpendicular
to the major dimension 106. Specific and non-limiting examples of
an oblong cross-section are an ellipse 104a (i.e., substantially
defined by the mathematical equation for an ellipse, as in FIG.
11), an oval 104b (i.e., "egg-shaped," as in FIG. 12), and an
obround 104c (i.e., straight line segments that are parallel with
hemispherical ends, as in FIG. 13). It is noted that the obround
cross-section 104c includes flats, but being parallel, do not
define a corner that must be transitioned. Herein, the oblong
cross-sections are referred to collectively or generically by
numerical reference 104, while specific or individual oblong
cross-sections are by a letter suffix following the numerical
reference 104 (e.g., the elliptical cross-section 104a).
[0062] In some embodiments, the oblong cross-section 104 is
continuously curved. Herein, a "continuously curved" oblong
cross-section does not include any linear segments. Accordingly,
the elliptical cross-section 104a and the oval cross-section 104b
are continuously curved, whereas the obround cross-section is not
continuously curved.
[0063] In some embodiments, the oblong cross-section 104 is
axisymmetric. Herein, for an "axisymmetric" cross-section, any line
112 that passes through a center point 110, regardless of
direction, also defines diametrically opposed intersection points
114 and 116 that are equidistant from the center point 110, as
illustrated for the obround cross-section 104c (FIG. 13).
Accordingly, the elliptical cross-section 104a and the obround
cross-section 104c are axisymmetric, whereas the oval cross-section
104b is not axisymmetric.
[0064] The oblong cross-sections 104 may be characterized by a
ratio R of the major dimension to the minor dimension. In some
embodiments, the ratio R is in a range of 1.05 to 1.20 inclusive.
Herein, a range that is said to be "inclusive" includes the stated
end point values of the range and all values therebetween. In some
embodiments, the ratio R is in a range of 1.05 to 1.15 inclusive.
In some embodiments, the ratio R is in a range of 1.07 to 1.12
inclusive.
[0065] Referring again to FIGS. 1 through 9, each of the opposing
side walls 46 and 48 may define a side graft window 122 that passes
therethrough. The side graft window 122 may define an elongate slot
124 ("elongate" being defined as having a major and a minor
dimension, the major dimension defining an "elongate" direction).
The elongate slot 124 may extend substantially parallel to the cage
axis 36. In various embodiments, the proximal wall 42 defines an
exterior recess 126 bounded by a distal face 129 that faces in a
proximal direction 61 (FIG. 3). The proximal wall 42 may further
define a through-hole 128 that extends distally from the distal
face 129 of the exterior recess 126 and is concentric about the
cage axis 36. The through-hole 128 may be tapped to define interior
threads 130 (FIG. 3). The exterior recess 126 may be polygonal
(e.g., triangular, square, rectangular, hexagonal, octagonal).
[0066] In some embodiments, the outer surface 70 of the nose
portion 34 may have the geometric characteristics of a one-sheeted
hyperboloid--i.e., concave (hyperbolic) profiles that may define
different shapes (different hyperbolas) in directions that are
perpendicular to each other, the hyperbolic surface defining oblong
(elliptical) cross-sections along a central axis. One sheeted
hyperboloids are described, for example, by Weisstein, Eric W.
"One-Sheeted Hyperboloid", from MATHWORLD--A WOLFRAM WEB RESOURCE
(available at
http://mathworld.wolfram.com/One-SheetedHyperboloid.html, last
visited Dec. 7, 2016), the disclosure of which is incorporated by
reference herein except for any express definitions contained
therein. Of course, while the disclosed outer surface 70 of the
nose portion 34 may include a portion that has these general
characteristics, strict adherence to any mathematical formulae is
optional.
[0067] In various embodiments, the interbody implant 30 is
fabricated from biologically inactive materials, which may be
metallic or non-metallic. Metallic biologically inactive materials
may include certain stainless steel alloys, titanium, tantalum, or
other alloys and materials which are structurally, chemically, and
biologically appropriate. Non-metallic biologically inactive
materials include certain plastics or polymers, organic and
inorganic resins, composites, and ceramics, (e.g., polyester ketone
or polyether ether ketone). The polymers may be non-porous. The
composites may include carbon fiber reinforced materials.
Appropriate ceramics may be porous and can be of an "open scaffold"
type which allow bone fusion growth through the ceramic material
itself.
[0068] Referring to FIGS. 14 through 19, an inserter 150 for
inserting an interbody implant 30 is depicted according to an
embodiment of the disclosure. The inserter 150 includes a shaft
assembly 152 having a proximal end 154 and a distal end 156. The
shaft assembly 152 may include an inner shaft 162 rotatable and
translatable within an outer sheath 164 and about an actuation axis
158 of the inserter 150. The outer sheath 164 may include
telescoping tubes 168. In the depicted embodiment, the inner shaft
162 defines the distal end 156 of the shaft assembly 152 and is
coupled to a knob 166 at the proximal end 154 of the shaft assembly
152. A handle assembly 170 may be coupled to the outer sheath 164
at the proximal end 154 of the shaft assembly 152. In the depicted
embodiment, the handle assembly 170 includes a T-shaped handle 171.
Also in the depicted embodiment, a guide wire passage 172 is
defined that is concentric about the actuation axis 158 and passes
through the knob 166, the inner shaft 162, and the distal end 156
of the inserter 150. In some embodiments, a channeled knob 166a is
utilized as the knob 166, the channeled knob 166a defining at least
one radially extending channel 169 that extends from the guide wire
passage 172.
[0069] In the depicted embodiment, a mounting interface 180 is
disposed at the distal end 156. The mounting interface 180 includes
a boss 182 configured for complementary insertion into the recess
126 of the proximal wall 42 of the interbody implant 30. The boss
182 is coupled to the outer sheath 164 and configured so that the
inner shaft 162 is rotatable within the boss 182. In some
embodiments, a threaded tip 184 is formed on or otherwise coupled
to the distal end 156 of the inner shaft 162, for threaded
engagement with the interior threads 130 of the through-hole
128.
[0070] In operation, the interbody implant 30 is aligned with the
mounting interface 180 and the boss 182 is inserted into the recess
126. The threaded tip 184 is screwed into the interior threads 130
by rotating the inner shaft 162 with the knob 166. Once the
interbody implant 30 is affixed to the distal end 156 of the
inserter 150, the implant 30 can be manipulated with the handle
assembly 170 by grasping the T-shaped handle 171. A guide wire 188,
such as a Kirschner or "K-wire," may be inserted into the guide
wire passage 172, through the knob 166, inner shaft 162, mounting
interface 180, and the through-passage 68 of the interbody implant
30, the guide wire 188 extending distal to the distal extremity 64
of the interbody implant 30 (FIG. 16). For embodiments implementing
the channeled knob 166a, the guide wire 188 may be folded away from
the 158 actuation axis so that a folded end 192 of the guide wire
188 is routed through the radially extending channel 169 (FIGS.
17-19) once the guide wire 188 is positioned within the patient.
The radially extending channel(s) 169 may be configured so that the
folded end 192 of the guide wire 188 is recessed from a proximal
surface 194 of the channeled knob 166a (FIG. 19).
[0071] Functionally, the boss 182 provides rotation control of the
interbody implant 30 by manipulating the inserter 150 with the
handle assembly 170. The T-shaped handle 171 provides gripping of
the handle assembly 170 that enables the user a full range of
manipulation of the inserter 150 and implant 30: translation along
and roll about the x-axis, pitch about the y-axis, and yaw about
the z-axis (FIG. 16). The guide wire 188 helps locate and guide the
interbody implant 30 to the desired implant location. Upon
achieving the desired insertion of the interbody implant 30 into a
spine of a patient, the inserter 150 may be decoupled from the
interior threads 130 of the through-passage 128 by retracting the
guide wire 188 proximally through the inserter 150 and unscrewing
threaded tip 184 from the through-hole 128 with the knob 166. The
folding of the guide wire 188 and positioning of the folded end 192
within the radially extending channel 169 enables a surgeon to tamp
the proximal face 194 of the channeled knob 166a without directly
impacting the guide wire 188, thereby preventing damage to both the
guide wire 188 and the channeled knob 166a.
[0072] Referring to FIGS. 20 and 21, an interbody implant kit 200
is depicted in an embodiment of the disclosure. The kit 200 may
include a case 202 that holds a tray 204 having caddies 206, each
caddy 206 including a selection of interbody implants 30 of
different sizes. Each caddy 260 may hold implants of uniform
length, for example, one of 27 mm, 30 mm, or 33 mm. An example and
non-limiting width of the implants is 9.5 mm. In some embodiments,
each caddy 206 includes paired implants of various heights, for
example, heights of 9 mm, 10 mm, 11 mm, 12 mm, 13 mm, 14 mm, and 15
mm. a pair of each height implant, with implant. Herein, "height"
refers to the dimension that is generally in the superior/inferior
direction of an implanted implant, "length" refers to the dimension
that is generally in the posterior/anterior direction of an
implanted implant, and "width" refers to the dimension that is
generally in the lateral direction of an implanted implant.
[0073] In some embodiments, the kit 200 includes one or more
inserters 150, as well as a tamping hammer 208, mounted to a tray
212 that also fits within the case 202. The kit 200 may also
include non-transient instructions on a tangible medium (e.g., on a
paper document, compact disk, flash drive) for assembly and
operation of the inserter 150 and interbody implant 30.
[0074] The kit 200 may also include instructions for implantation
of the interbody implants 30, the instructions being on a tangible,
non-transitory medium (e.g., a printed document or a computer
readable medium such as a compact disk, flash drive, or hard
drive).
[0075] Referring to FIGS. 22 through 25, an interbody implant 30b
is depicted according to an embodiment of the disclosure. The
interbody implant 30b includes many of the same components and
attributes as the interbody implant 30a, which are indicated with
same-numbered reference characters. In addition, the opposed edge
surfaces 52, 54 of the interbody implant 30b each define a convex
baseline 250 that is arcuate about a lateral axis 252, the lateral
axis 252 being perpendicular to the cage axis 36. In some
embodiments, gripping facets 57b project outward from (i.e., away
from the lateral axis 252) the convex baselines 250.
[0076] Herein, a "baseline" of the edge surfaces 52, 54 is a datum
that passes through the local minima 254 located between proud
projections 256 of the gripping facets 57 (depicted with dashed
lines in FIG. 25). The convex baseline 250 may be characterized by
a minimum height H1 and a maximum height H2 of the opposing side
walls 46 and 48. In some embodiments dimension of the convexity of
the convex baseline (H2-H1) is in a range of 1 mm to 5 mm
inclusive; in some embodiments dimension of the convexity of the
convex baseline (H2-H1) is in a range of 2 mm to 4 mm inclusive. In
some embodiments, each of the plurality of gripping facets 57b
defines a ridge 258 that extends along a ridge line 260, as
depicted at FIG. 24. The ridge line 260 extends proximally at a
swept angle .PHI. relative to the cage axis 36, the swept angle
.PHI. defining an acute angle relative to the cage axis 36.
[0077] Functionally, the convex baselines 250 of the opposed edge
surfaces 52, 54 better conform to the concave endplates of the
vertebrae to which the interbody implant 30b is engaged. Because
the convex baseline 250 is more complementary to the concave shape
of the end plate of the engaged vertebrae, the load imposed between
the vertebrae and the interbody implant 30b is distributed over a
greater area, thus avoiding stress concentrations at the interface
of the interbody implant 30b and the vertebral endplates. In this
way, tissue growth between the interbody implant 30b occurs faster
and more uniformly than with conventional implants having planar
superior and inferior baseline surfaces. The swept angles .PHI. of
the gripping facets 57b may reduce the resistance to insertion of
the interbody implant 30b relative to the resistance of withdrawal
of the interbody implant 30b, thereby favoring retention while
easing implantation of the interbody implant 30b. Accordingly, the
retention characteristics of the gripping facets 57b do not rely on
projections that define a relatively sharp edge, so the tops of the
gripping facets 57b may be blunted.
[0078] Referring to FIGS. 26 through 28, an interbody implant 30c
is depicted according to an embodiment of the disclosure. The
interbody implant 30c may include many of the same components and
attributes as the interbody implant 30b, which are indicated with
same-numbered reference characters. In addition, the nose portion
34 of the interbody implant 30c defines a forward or distal slot
270 that extends from the through-passage 68 of the nose portion 34
in one direction and through the outer surface 70 of the nose
portion 34, as depicted in FIG. 28. The distal slot 270 is coplanar
with the nose axis 38 and defines a gap dimension 272 that is less
than a minimum diameter 274 of the through-passage 68.
[0079] Referring to FIGS. 29 through 31, an interbody implant 30d
is depicted according to an embodiment of the disclosure. The
interbody implant 30d may include many of the same components and
attributes as the interbody implants 30b and 30c, which are
indicated with same-numbered reference characters. In addition, the
cage portion 32 of the interbody implant 30d defines a rearward or
proximal slot 280 that extends from the through-passage 128 of the
cage portion 32 in one direction and through the outer surface of
the proximal portion 41 (FIGS. 29 and 31). The proximal slot 280
may be coplanar with the cage axis 36. In some embodiments, the
proximal slot 280 defines a gap dimension 282 that is less than a
minimum diameter 284 of the through-passage 128.
[0080] Referring to FIGS. 32 through 34, an interbody implant 30e
is depicted according to an embodiment of the disclosure. The
interbody implant 30e includes many of the same components and
attributes as the interbody implant 30d, which are indicated with
same-numbered reference characters. A modification to the interbody
implant 30e relative to the interbody implant 30d is that the
proximal slot 280, while still coplanar with the cage axis 36, does
not extend from the through-passage 128 of the cage portion 32.
Rather, a ring or surround 288 of material is continuous about
through-passage 128, as depicted in the cross-section of the
proximal portion 41 in FIG. 34.
[0081] Referring to FIGS. 35 through 37, an interbody implant 30f
is depicted according to an embodiment of the disclosure. The
interbody implant 30f includes many of the same components and
attributes as the interbody implant 30e, which are indicated with
same-numbered reference characters. A modification to the interbody
implant 30f relative to the interbody implant 30e is presence of
ribs 292 that bridge the distal slot 270. In the depicted
embodiment, the ribs 292 are flush with the diameter of the
through-passage 68, so that the cross section of the
through-passage 68 is continuous about the nose axis 38 at the
location of the ribs 292. The ribs 292 may be disposed at the
distal wall 44 of the cage portion 32 and at the distal extremity
64 of the nose portion 34 (depicted).
[0082] Functionally, the distal and proximal slots 270 and 280
provide additional paths for tissue to grow into and through the
interbody implant 30, thus promoting a faster and more secure
fusion between the vertebrae. For the interbody implant 30e, the
surround 288 of material reinforces the through-passage 128 to
maintain the integrity of the recess 126 under the torsion that may
be applied to the interbody implant 30e during implantation. The
ribs 292 prevents the guide wire 188 from entering and becoming
jammed in the distal slot 270.
[0083] The interbody implants 30 depicted herein include a variety
of combinations that are non-essential. For example, the interbody
implants depict gripping facets 57 on both the of the opposed edge
surfaces 52, 54; embodiments are contemplated wherein gripping
facets 57 are provided on only one of the opposed edge surfaces 52,
54. The interbody implants 30b through 30f depict both of the
opposed edge surfaces 52 and 54 as defining the convex baseline
250; embodiments are contemplated wherein the convex baseline 250
is defined by only one of the opposed edge surfaces 52 or 54. The
interbody implants 30c through 30f are depicted as including distal
and proximal slots 270 and 280 that are co-planar; embodiments are
contemplated where the distal and proximal slots are not co-planar.
The co-planar slots 270 and 280 are disclosed as defining gap
dimensions 272 and 282, respectively, that are less than a minimum
diameter 284 of the through-passage 128; embodiments are
contemplated where one or both of the gap dimensions 272 and 282
are the same or greater than the minimum diameter 284 of the
through-passage 128. The interbody implant 30f depicts two ribs 292
that bridge the distal slot 270; a single rib 292 bridging the
distal slot 270 is also contemplated, for example at the distal
wall 44 only, the distal extremity 64 only, or at a location
therebetween.
[0084] Each of the additional figures and methods disclosed herein
can be used separately, or in conjunction with other features and
methods, to provide improved devices and methods for making and
using the same. Therefore, combinations of features and methods
disclosed herein may not be necessary to practice the disclosure in
its broadest sense and are instead disclosed merely to particularly
describe representative and preferred embodiments.
[0085] Various modifications to the embodiments may be apparent to
one of skill in the art upon reading this disclosure. For example,
persons of ordinary skill in the relevant arts will recognize that
the various features described for the different embodiments can be
suitably combined, un-combined, and re-combined with other
features, alone, or in different combinations. Likewise, the
various features described above should all be regarded as example
embodiments, rather than limitations to the scope or spirit of the
disclosure.
[0086] Persons of ordinary skill in the relevant arts will
recognize that various embodiments can comprise fewer features than
illustrated in any individual embodiment described above. The
embodiments described herein are not meant to be an exhaustive
presentation of the ways in which the various features may be
combined. Accordingly, the embodiments are not mutually exclusive
combinations of features; rather, the claims can comprise a
combination of different individual features selected from
different individual embodiments, as understood by persons of
ordinary skill in the art.
[0087] The following documents are incorporated by reference herein
in their entirety: U.S. Patent Application Publication No.
2006/0167548 to Jackson; U.S. patent application Ser. No.
29/593,823 to Abbasi entitled "Spinal Fusion Cage", filed Feb. 13,
2017; U.S. patent application Ser. No. 29/608,791 to Abbasi
entitled "Spinal Fusion Cage", filed Jun. 26, 2017. Incorporation
by reference of these documents is limited such that no subject
matter is incorporated that is contrary to the explicit disclosure
herein. Any incorporation by reference of documents above is
further limited such that no claims included in the documents are
incorporated by reference herein. Any incorporation by reference of
documents is yet further limited such that any definitions provided
in the documents are not incorporated by reference herein unless
expressly included herein.
[0088] Unless indicated otherwise, references to "embodiment(s)",
"disclosure", "present disclosure", "embodiment(s) of the
disclosure", "disclosed embodiment(s)", and the like contained
herein refer to the specification (text, including the claims, and
figures) of this patent application that are not admitted prior
art.
[0089] For purposes of interpreting the claims, it is expressly
intended that the provisions of 35 U.S.C. 112(f) are not to be
invoked unless the specific terms "means for" or "step for" are
recited in the respective claim.
* * * * *
References