U.S. patent application number 16/294555 was filed with the patent office on 2019-09-26 for spinal fixation constructs and related methods.
The applicant listed for this patent is NuVasive, Inc.. Invention is credited to Robert Shay Bess, Regis W. Haid, Frank Schwab, Christopher Shaffrey.
Application Number | 20190290329 16/294555 |
Document ID | / |
Family ID | 67983102 |
Filed Date | 2019-09-26 |
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United States Patent
Application |
20190290329 |
Kind Code |
A1 |
Bess; Robert Shay ; et
al. |
September 26, 2019 |
Spinal Fixation Constructs and Related Methods
Abstract
This disclosure describes a variety of transitional or terminal
components that may be implanted as part of a spinal fixation
construct to decrease the potential for subsequent development of
junctional disease. The fixation construct may extend any number of
levels from a single level construct to a long construct spanning
multiple spinal levels and multiple spinal regions from the
lumbosacral to cervical regions, and with any variety of
combination of anchors, rods, and connectors. Terminal and/or
transitional components maybe utilized at the caudal and or
cephalad ends of the fixation construct to reduce stresses endured
by the construct adjacent pathology and prevent or reduce incidence
and degree of junctional disease.
Inventors: |
Bess; Robert Shay; (San
Diego, CA) ; Haid; Regis W.; (San Diego, CA) ;
Schwab; Frank; (San Diego, CA) ; Shaffrey;
Christopher; (San Diego, CA) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
NuVasive, Inc. |
San Diego |
CA |
US |
|
|
Family ID: |
67983102 |
Appl. No.: |
16/294555 |
Filed: |
March 6, 2019 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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14703852 |
May 4, 2015 |
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16294555 |
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61988066 |
May 2, 2014 |
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Current U.S.
Class: |
1/1 |
Current CPC
Class: |
A61B 17/7028 20130101;
A61B 17/7032 20130101; A61B 17/7023 20130101; A61B 17/7041
20130101; A61B 17/7011 20130101; A61B 17/7022 20130101; A61B 17/705
20130101; A61B 17/7043 20130101; A61B 17/7035 20130101; A61B
17/7053 20130101; A61B 17/7008 20130101; A61B 17/7019 20130101;
A61B 17/702 20130101; A61B 17/7001 20130101 |
International
Class: |
A61B 17/70 20060101
A61B017/70 |
Claims
1. A rod attachment for securing a spinal rod to a bone structure,
the rod attachment comprising: a first side, a second side, and a
lumen extending longitudinally along a first axis through the first
side and the second side of the rod attachment, the lumen
dimensioned to receive the spinal rod and wherein the first lumen
is configured to allow the spinal rod to enter from the first side
and exit the lumen from the second side; a third side of the rod
attachment including at least one aperture, wherein the at least
one aperture intersects the lumen along a second axis about
perpendicular to the first axis; and a fourth side of the rod
attachment including a tether connector, wherein the tether
connector is configured to receive a tether parallel to and offset
from the second axis.
2. The rod attachment of claim 1, wherein the lumen has an enclosed
perimeter.
3. The rod attachment of claim 1, wherein the rod attachment
further comprises: a housing section that contains the lumen, the
at least one aperture, and the tether connector.
4. The rod attachment of claim 1, wherein the tether connector
comprises: a post member extending outwardly from the fourth side;
and a second lumen extending through the post member.
5. The rod attachment of claim 4, wherein the lumen does not
intersect the second lumen.
6. The rod attachment of claim 1, wherein the rod attachment
further comprises: at least one locking element in the at least one
aperture.
7. The rod attachment of claim 6, wherein the at least one aperture
comprises an aperture screw thread, wherein the at least one
locking element comprises a locking screw thread, and wherein the
aperture screw thread and the locking screw thread are
complementary.
8. The rod attachment of claim 7, wherein the aperture screw thread
is configured to engage with the locking screw thread as the at
least one locking element is advanced via rotation in the at least
one aperture.
9. A rod attachment for securing a spinal rod to a bone structure,
the rod attachment comprising: a first side, an second side and a
first lumen extending longitudinally through the first side of the
rod attachment and the second side of the rod attachment, wherein
the first lumen is dimensioned to receive the spinal rod and
configured to allow the spinal rod to enter from the first side and
exit the first lumen from the second side; a third side having a
first aperture and a second aperture, wherein the first aperture
and the second aperture each intersect the first lumen; and a
fourth side including a tether connector, wherein the tether
connector comprises a post member extending outwardly from the
fourth side, wherein the post member comprises a second lumen
dimensioned to receive a tether.
10. The rod attachment of claim 9, wherein the rod attachment
further comprises: a housing section that contains the first lumen,
the first aperture, the second aperture, and the tether
connector.
11. The rod attachment of claim 9, wherein the first lumen does not
intersect the second lumen.
12. The rod attachment of claim 9, wherein the rod attachment
further comprises: a first locking element in the first aperture;
and a second locking element in the second aperture.
13. The rod attachment of claim 12, wherein the first and second
apertures comprise aperture screw threads, wherein the first and
second locking elements comprise locking screw threads, and wherein
the aperture screw threads and the locking screw threads are
complementary.
14. A bone anchor for securing a spinal rod to a bone structure,
the bone anchor comprising: a threaded shank; and a housing
comprising: a base coupled to the threaded shank; a pair of
upstanding arms spaced apart forming a channel dimensioned to fit a
portion of the spinal rod; and a tether connector on a given arm of
the pair of upstanding arms.
15. The bone anchor of claim 14, wherein the housing is coupled to
the threaded shank in a multi-axial configuration in which the
housing can rotate and pivot relative to the threaded shank.
16. The bone anchor of claim 14, wherein the tether connector
comprises: a post member extending outwardly from the given arm;
and a lumen extending through the post member.
17. The bone anchor of claim 16, wherein the channel does not
intersect the lumen.
18. The bone anchor of claim 14, wherein the bone anchor further
comprises: a locking element that is attachable to the housing
between the pair of upstanding arms.
19. The bone anchor of claim 18, wherein the locking element
comprises an upper portion that mates with the pair of upstanding
arms and a lower portion that engages with a given portion of the
spinal rod.
20. The bone anchor of claim 18, wherein each arm of the pair of
upstanding arms comprises a locking engagement feature configured
to engage with a housing engagement feature of the locking element
as the locking element is advanced via rotation between the pair of
upstanding arms.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application is continuation of U.S. patent application
Ser. No. 14/703,852 filed on May 4, 2015, which claims the benefit
of priority under 35 U.S.C. .sctn. 119(e) to U.S. Provisional
Application 61/988,066, filed on May 2, 2014, the entire contents
of which are incorporated by reference into this disclosure as if
set forth in its entirety herein.
FIELD
[0002] The present application relates generally to implants and
methods used with, or forming part of, a spinal fixation construct
and directed at preventing the occurrence of or reducing the degree
of adjacent segment pathology and failures occurring at either the
distal junction (DJK) or proximal junction (PJK).
BACKGROUND
[0003] The spine is formed of a column of vertebra that extends
between the cranium and pelvis. The three major sections of the
spine are known as the cervical, thoracic and lumbar regions. There
are 7 cervical vertebrae (C1-C7), 12 thoracic vertebrae (T1-T12),
and 5 lumbar vertebrae (L1-L5), with each of the 24 vertebrae being
separated from each other by an intervertebral disc. A series of
about 9 fused vertebrae extend from the lumbar region of the spine
and make up the sacral and coccygeal regions of the vertebral
column. The natural curvature of the spine includes a combination
of lordosis and kyphosis. Specifically, the cervical and lumbar
portions of the spine exhibit a natural lordotic curvature, meaning
that they are set in a curve that is anteriorly convex (and
posteriorly concave). The thoracic portion of the spine has a
naturally kyphotic curvature, meaning that it is set in a curve
that is anteriorly concave (and posteriorly convex).
[0004] The main functions of the spine are to provide skeletal
support and protect the spinal cord. Even slight disruptions to
either the intervertebral discs or vertebrae can result in serious
discomfort as well as compression of nerve fibers either within the
spinal cord or extending from the spinal cord. If a disruption to
the spine becomes severe enough, severe pain, disability and damage
to a nerve or part of the spinal cord may occur and can result in
partial to total loss of bodily functions (e.g., walking, talking,
breathing, etc.). Therefore, it is of great interest and concern to
be able to both correct and prevent any ailments of the spine.
[0005] Fixation systems are often surgically implanted to stabilize
or immobilize a portion of the spine. They are generally utilized
during spinal fusion procedures to immobilize the applicable
vertebrae until bone growth occurs to effect the fusion and/or to
correct vertebral alignment issues. Fixation systems often use a
combination of rods, plates, pedicle screws, and bone hooks to
attach a fixation construct to the affected vertebrae. The
configuration required for each procedure and patient varies due to
the ailment being treated, the specific method of treatment (e.g.
surgical approach, etc. . . . ) and the patient's specific
anatomical characteristics.
[0006] Depending upon the pathology presented, correction of spinal
ailments may involve only one vertebral level (i.e. a single
intervertebral disc and the two vertebral bodies adjacent that
intervertebral disc) or multiple spinal levels. An extreme example
of a multiple level treatment relates to deformity correction (e.g.
scoliosis correction) in which a screw and rod construct is
implanted along a significant length of the spine in an attempt to
forcibly correct or maintain a desired spinal alignment.
[0007] Whatever the treatment, the goal remains to improve the
quality of life for the patient. In the vast majority of cases this
goal is achieved, however in some instances patients who receive
implants to treat the primary pathology develop a secondary
condition called junctional disease. Most commonly this occurs at
the proximal or cephalad area of spinal instrumentation and is then
termed adjacent segment pathology. Clinical Adjacent Segment
Pathology (CASP) refers to clinical symptoms and signs related to
adjacent segment pathology. Radiographic Adjacent Segment Pathology
(RASP) refers to radiographic changes that occur at the adjacent
segment. A subcategory of CASP and RASP that occurs at the proximal
end of the instrumentation is termed proximal junctional kyphosis
(PJK). PJK may be defined in several manners and commonly is
specified as kyphosis measured from one segment cephalad to the
upper end instrumented vertebra to the proximal instrumented
vertebra with abnormal value defined as 10 degrees or greater. In
practice this often means that the patient's head and/or shoulders
tend to fall forward to a greater degree than should normally
occur. Sometimes the degree is significant.
[0008] Adjacent segment pathology can occur as either a
degenerative, traumatic or catastrophic condition and sometimes as
a result from a combination of factors. Degenerative conditions are
ones that occur over a period of time, normally 5 or 6 years but
can occur at an accelerated rate particularly with altered
mechanics related to spinal fusion. As a result the patient's head
and/or shoulder region(s) fall forward gradually over time.
Traumatic and catastrophic conditions occur as a generally sudden
shifting of the vertebral body immediately cephalad to the upper
end instrumented vertebra and can lead to sudden changes in spinal
alignment with marked symptoms noted by the patient.
[0009] Whether the condition is degenerative, traumatic or
catastrophic, the exact cause of adjacent segment pathology is
uncertain. Generally, it is believed that adjacent segment
pathology and more specifically PJK is a result of excess strain
and stress on the proximal instrumented spinal segment which is
then at least partially transferred to the bone structures, disc,
ligaments and other soft tissues, causing a loss of normal
structural integrity and mechanical properties. The resultant
effect can be a forward (i.e. kyphotic) shift of the adjacent
non-instrumented vertebral body. One such theory is that this
strain and stress is caused by suboptimal alignment and/or balance
of the screw and rod construct. Another theory is that the rigidity
of the screw and rod construct causes the problem in that the
transition from a motion-restrained segment to a
motion-unrestrained segment is too much for the non-instrumented
(unrestrained) segment to handle over time. Yet another theory
speculates that the specific level at which the proximal
instrumented vertebra is located is of vital importance in that
some levels may be better suited to handle a proximal termination
of a fixation construct than others.
[0010] Thus there remains a need for continued improvements and new
systems for spinal fixation with a specific goal of preventing the
occurrence of or reducing the degree of adjacent segment pathology
and failures occurring at either the distal junction (DJK) or
proximal junction (PJK). The implants and techniques described
herein are directed towards overcoming these challenges and others
associated with posterior spinal fixation.
BRIEF DESCRIPTIONS OF THE DRAWINGS
[0011] Many advantages of the present invention will be apparent to
those skilled in the art with a reading of this specification in
conjunction with the attached drawings, wherein like reference
numerals are applied to like elements and wherein:
[0012] FIG. 1 is a perspective view of one example of a vertebral
fixation system including various elements described in this
disclosure;
[0013] FIGS. 2 and 3 are perspective views of one example of a
fixed angle bone anchor forming part of the vertebral fixation
system of FIG. 1;
[0014] FIGS. 4 and 5 are perspective sectional views of the bone
anchor of FIG. 2;
[0015] FIGS. 6 and 7 are perspective views of another example of a
fixed angle bone anchor forming part of the vertebral fixation
system of FIG. 1;
[0016] FIG. 8 is a perspective sectional view of the bone anchor of
FIG. 6;
[0017] FIGS. 9 and 10 are perspective and sectional views,
respectively, of a locking element forming part of the bone anchor
of FIG. 6;
[0018] FIGS. 11 and 12 are perspective views of still another
example of a fixed angle bone anchor forming part of the vertebral
fixation system of FIG. 1;
[0019] FIGS. 13 and 14 are perspective sectional views of the bone
anchor of FIG. 11;
[0020] FIGS. 15 and 16 are perspective views of one example of a
polyaxial bone anchor forming part of the vertebral fixation system
of FIG. 1;
[0021] FIGS. 17 and 18 are perspective sectional views of the bone
anchor of FIG. 15;
[0022] FIGS. 19 and 20 are perspective and sectional views,
respectively, of a rod seat insert forming part of the bone anchor
of FIG. 15;
[0023] FIGS. 21 and 22 are perspective views of another example of
a polyaxial bone anchor forming part of the vertebral fixation
system of FIG. 1;
[0024] FIG. 23 is a perspective sectional view of the bone anchor
of FIG. 21;
[0025] FIGS. 24 and 25 are perspective views of another example of
a fixed angle bone anchor forming part of the vertebral fixation
system of FIG. 1;
[0026] FIGS. 26 and 27 are perspective sectional views of the bone
anchor of FIG. 24;
[0027] FIGS. 28-30 are perspective views of an example of a bone
anchor having a translating tulip configured for use with and
forming part of the vertebral fixation system of FIG. 1;
[0028] FIGS. 31 and 32 are sectional views of the bone anchor of
FIG. 28;
[0029] FIG. 33 is a plan view of a translation base forming part of
the bone anchor of FIG. 28;
[0030] FIGS. 34 and 35 are sectional and perspective views,
respectively, of a rod-receiving member forming part of the bone
anchor of FIG. 28;
[0031] FIG. 36 is a perspective view of an example of a bone anchor
with attached tether configured for use with and forming part of
the vertebral fixation system of FIG. 1;
[0032] FIG. 37 is a perspective view of an example of a rod
attachment with attached tether configured for use with and forming
part of the vertebral fixation system of FIG. 1;
[0033] FIG. 38 is a plan view of the bone anchor of FIG. 36 and the
rod attachment of FIG. 37 in use on a human spine;
[0034] FIGS. 39 and 40 are perspective view of still another
example of a bone anchor suitable for use with the vertebral
fixation system of FIG. 1;
[0035] FIG. 41 is a sectional view of the bone anchor of FIG.
39;
[0036] FIGS. 42 and 43 are perspective view, respectively, of the
bone anchor of FIG. 39 in use with an example of a flexible rod
suitable for use with the vertebral fixation system of FIG. 1;
[0037] FIG. 44 is a sectional view of the bone anchor and flexible
rod combination of FIG. 42;
[0038] FIG. 45 is a plan view of a portion of a spine with an
implanted transition apparatus suitable for use with the vertebral
fixation system of FIG. 1;
[0039] FIG. 46 is a perspective view of the transition apparatus of
FIG. 45;
[0040] FIG. 47 is a perspective view of a rod-cord hybrid forming
part of the transition apparatus of FIG. 45;
[0041] FIG. 48 is a side plan view of the transition apparatus of
FIG. 45;
[0042] FIG. 49 is a perspective view of another example of a
transition apparatus suitable for use with the vertebral fixation
system of FIG. 1;
[0043] FIG. 50 is a perspective view of a housing unit forming part
of the transition apparatus of FIG. 49;
[0044] FIGS. 51 and 52 are plan and top sectional views,
respectively, of the transition apparatus of FIG. 49;
[0045] FIG. 53 is a side sectional view of the transition apparatus
of FIG. 49;
[0046] FIG. 54 is an exploded view of a spinal rod terminus forming
part of the transition apparatus of FIG. 49;
[0047] FIGS. 55 and 56 are perspective views of the transition
apparatus of FIG. 49;
[0048] FIG. 57 is a perspective view of yet another transition
apparatus suitable for use with the vertebral fixation system of
FIG. 1;
[0049] FIGS. 58 and 59 are plan views of the transition apparatus
of FIG. 57;
[0050] FIG. 60 is an exploded perspective view of the transition
apparatus of FIG. 57;
[0051] FIG. 61 is an exploded sectional view of the transition
apparatus of FIG. 57;
[0052] FIG. 62 is a perspective view of another example of a
transition apparatus suitable for use with the vertebral fixation
system of FIG. 1;
[0053] FIG. 63 is a partially exploded sectional view of the
transition apparatus of FIG. 62;
[0054] FIG. 64 is an exploded sectional view of the transition
apparatus of FIG. 62;
[0055] FIG. 65 is a plan view of a partial spine with another
example of a bone anchor suitable for use with the vertebral
fixation system of FIG. 1 attached thereto;
[0056] FIG. 66 is a perspective view of the bone anchor of FIG.
65;
[0057] FIG. 67 is a side plan view of the bone anchor of FIG.
65;
[0058] FIG. 68 is a perspective view of a locking element forming
part of the bone anchor of FIG. 65;
[0059] FIGS. 69 and 70 are perspective views of an example of a rib
clamp forming part of a bone anchor suitable for use with the
vertebral fixation system of FIG. 1;
[0060] FIG. 71 is an exploded plan view of the rib clamp of FIG.
69;
[0061] FIG. 72 is a plan view of the bone anchor of FIG. 69
implanted within a human spine;
[0062] FIGS. 73-75 are perspective views of an alternative example
of a rib clamp forming part of the bone anchor of FIG. 72;
[0063] FIG. 76 is an exploded plan view of the rib clamp of FIG.
73;
[0064] FIGS. 77 and 78 are perspective views of another example of
a bone anchor forming part of the vertebral fixation system of FIG.
1;
[0065] FIG. 79 is an exploded perspective view of the bone anchor
of FIG. 77;
[0066] FIG. 80 is a plan view of the bone anchor of FIG. 77;
[0067] FIG. 81 is a plan view of the bone anchor of FIG. 77
implanted within a human spine;
[0068] FIG. 82 is a perspective view of an example of a bone anchor
having a rod bumper configured for use with the spinal fixation
system of FIG. 1;
[0069] FIGS. 83 and 84 are perspective and plan views,
respectively, of the spinal rod and rod bumper of FIG. 82;
[0070] FIG. 85 is a perspective view of the rod bumper of FIG.
82;
[0071] FIG. 86 is a perspective view of a locking element forming
part of the bone anchor of FIG. 82;
[0072] FIG. 87 is a perspective view of an alternative example of a
bone anchor and rod bumper combination configured for use with the
spinal fixation system of FIG. 1;
[0073] FIGS. 88 and 89 are perspective and plan views,
respectively, of the spinal rod and rod bumper of FIG. 87;
[0074] FIG. 90 is a perspective view of the rod bumper of FIG.
87;
[0075] FIG. 91 is a perspective view of a locking element forming
part of the bone anchor of FIG. 87;
[0076] FIGS. 92 and 93 are perspective and sectional views,
respectively of an example of a fixation assembly including an
elastomeric bumper configured for use with the spinal fixation
system of FIG. 1;
[0077] FIG. 94 is an exploded view of the fixation assembly of FIG.
92;
[0078] FIG. 95 is an exploded perspective view of the fixation
assembly of FIG. 92;
[0079] FIGS. 96 and 97 are perspective and sectional views,
respectively, of another example of a fixation assembly including
cable and a flexion stop configured for use with the spinal
fixation system of FIG. 1; and
[0080] FIG. 98 is an exploded view of the fixation assembly of FIG.
96.
DESCRIPTION OF THE PREFERRED EMBODIMENT
[0081] Illustrative embodiments of the invention are described
below. In the interest of clarity, not all features of an actual
implementation are described in this specification. It will of
course be appreciated that in the development of any such actual
embodiment, numerous implementation-specific decisions must be made
to achieve the developers' specific goals, such as compliance with
system-related and business-related constraints, which will vary
from one implementation to another. Moreover, it will be
appreciated that such a development effort might be complex and
time-consuming, but would nevertheless be a routine undertaking for
those of ordinary skill in the art having the benefit of this
disclosure. The vertebral fixation system and methods described
herein boast a variety of inventive features and components that
warrant patent protection, both individually and in
combination.
[0082] This disclosure describes a variety of transitional or
terminal components that may be implanted as part of a spinal
fixation construct to decrease the potential for subsequent
development of junctional disease or failure. In the examples shown
only the cephalad most level (for terminal hardware) or levels (for
multilevel transitional hardware) of the fixation construct (e.g.
those utilizing the exemplary components described herein) are
illustrated. It should be appreciated, however, that the entire
fixation construct may extend any number of levels from a single
level construct to a long construct spanning multiple spinal levels
and multiple spinal regions from the lumbosacral to cervical
regions (such as the example construct illustrated in FIG. 1), and
with any variety of combinations of known anchors, rods, and
connectors. It should also be appreciated that the exemplary
terminal and/or transitional components may additionally or
alternatively be utilized at the caudal end of the fixation
construct. Moreover, although the vertebral fixation systems
described herein may be used along any aspect of the spine (e.g.
anterior, posterior, antero-lateral, postero-lateral) they are
particularly suited for implantation along a posterior aspect of
the spine.
[0083] FIG. 1 illustrates an example of a vertebral fixation system
10 of the type that is used with the devices and methods described
in this disclosure. By way of example, the vertebral fixation
system 10 is a screw-and-rod construct adapted for implantation
along the posterior aspect of the human spinal column. The
vertebral fixation system 10 includes a pair of elongate rods 12
dimensioned to span multiple vertebral levels, a plurality of
threaded bone anchors 14, a plurality of hook-type bone anchors 16,
and a plurality of transverse connectors 22, 24 dimensioned to
rigidly engage each of the elongate rods 12 so as to hold each rod
in place relative to the other. The transverse connectors 22, 24
may be provided as fixed connectors 22 or adjustable connectors 24,
in any quantity that is required by the surgeon performing the
implantation surgery. Proximal bone anchors 18 are provided at the
proximal (cephalad) terminus of the assembly. Distal bone anchors
20 are provided at the distal (caudal) terminus of the assembly. It
is contemplated that any of the examples of bone anchors and other
transition assemblies described herein may be substituted for the
proximal bone anchors 18 and/or distal bone anchors 20 which are
traditionally rigid and identical to the other bone anchors used
throughout the construct. It is also contemplated that the examples
of flexible transition segments described herein may replace
existing hardware at the proximal and/or distal terminus of the
vertebral fixation system 10 such that there is no additional
surgical footprint realized. It is further contemplated that the
examples of flexible transition segments described herein may
augment existing hardware at the proximal and/or distal terminus of
the vertebral fixation system 10 such that there is additional
added surgical footprint realized. This may be more applicable with
the various embodiments to that can be installed with minimal
disruption of additional muscle tissue and/or ligament structure.
Finally, as previously noted junctional disease or failure can be a
problem at either the proximal terminus or the distal terminus (or
both) of vertebral fixation systems. Therefore, although the
various examples disclosed herein may be described in terms of
proximal terminus and proximal joint disease (for ease of
disclosure) it is to be understood that any of the example
embodiments are also applicable and may be used at the distal
terminus of the vertebral fixation system without deviating from
the scope of this disclosure.
[0084] FIGS. 2-5 illustrate a first example of a bone anchor
configured for use with the vertebral fixation system 10 described
above. By way of example, the bone anchor 30 is a fixed angle screw
having a housing 32 for capturing and locking therein a spinal rod
12, a shank 34 including a thread feature 36 suitable for stable
fixation to vertebral bone, and a locking element 38 configured for
locking the spinal rod 12 within the housing 32.
[0085] The housing 32 has a base 40 that mates (or is integrally
formed) with the shank 34 and a pair of upstanding arms 42
separated by and partially defining a rod channel 44 sized and
configured to receive the spinal rod 12 therein. The base includes
a recess 46 formed within the rod channel and configured to receive
a rod seat 48. The rod seat 48 is a block of material sized and
dimensioned to snugly fit within the recess 46 and having a concave
surface 50 that forms the lower portion of the rod channel 44. The
concave surface 50 is configured to engage the generally
cylindrical spinal rod 12 and provide a seat for the spinal rod 12.
Significantly, the rod seat 48 of the instant example may be formed
of a semi-rigid elastomeric material that allows for some movement
(e.g. vertical shifting, axial rotation, pivoting, and/or
translation) of the spinal rod 12 within the housing 32 while
maintaining a frictional association with the spinal rod 12 (and
thus preventing unrestricted movement of the rod). The upstanding
arms 42 include a locking element engagement feature 52 disposed on
the interior face of each arm 42. The locking element engagement
feature 52 mates with a complementary housing engagement feature 54
on the locking element 38, described in further detail below.
[0086] The locking element 38 is attachable to the housing 32 after
the spinal rod 12 has been seated within the rod channel 44. In the
example presently described, the locking element 38 comprises a
setscrew having a housing engagement feature 54 and a rod
engagement surface 56. The housing engagement feature 54
complementarily engages the locking element engagement feature 46
of the upstanding arms 42. The rod engagement surface 56 is
configured to engage the spinal rod 12 and may be planar, convex,
or concave. By way of example, the locking element 38 is made of a
rigid material (e.g. titanium).
[0087] In use, after the spinal rod 12 has been seated within the
rod channel 44, the locking element 38 is inserted between the
upstanding arms 42 such that the housing engagement feature 54 on
the locking element 38 engages the locking element engagement
features 46 on each of the upstanding arms 42. The locking element
38 is then advanced via rotation to exert a force on the spinal rod
12 and frictionally lock the spinal rod 12 within the housing 32
(and between the locking element 38 and the rod seat 48). After
implantation, the semi-rigid nature of the elastomeric rod seat 48
will allow the construct to absorb some force and experience some
potential alignment correction that may occur from natural shifting
of the patient's body, thereby potentially alleviating some
conditions that may lead to junctional disease or failure (e.g.
PJK, DJK, etc.).
[0088] In the instant example (and others described below), the
housing 32 and shank 34 are provided in a fixed relationship so
that no relative movement is possible between them. This may be
achieved by way of example through secure mating of separate parts
or by a single part having an integral housing 32 and shank.
Alternatively, the housing 32 and shank 34 may be mated with a
polyaxial engagement such that the housing 32 can pivot relative to
the shank 34 in any direction. The engagement may also be such that
the pivoting movement may be inhibited in one or more directions.
By way of example, the housing 32 and shank 34 may be mated with a
uniplanar engagement such that the housing 32 pivots relative to
the shank 32 in a single plane. Many of these alternative examples
are described in further detail below.
[0089] FIGS. 6-8 illustrate another example of a bone anchor
configured for use with the vertebral fixation system 10 described
above. By way of example, the bone anchor 60 is a fixed angle screw
having a housing 62 for capturing and locking therein a spinal rod
12, a shank 64 including a thread feature 66 suitable for stable
fixation to vertebral bone, and a locking element 68 configured for
locking the spinal rod 12 within the housing 62.
[0090] The housing 62 has a base 70 that mates (or is integrally
formed) with the shank 64 and a pair of upstanding arms 72
separated by and partially defining a rod channel 74 sized and
configured to receive the spinal rod 12 therein. The base includes
a rod seat 76 comprising an upward-facing concave surface that
forms the lower portion of the rod channel 74. The rod seat 76 is
configured to engage the generally cylindrical spinal rod 12 and
provide a seat for the spinal rod 12. In the instant example, the
rod seat 76 is composed of the same rigid material as the bone
anchor 60 (e.g. titanium). The upstanding arms 72 include a locking
element engagement feature 78 disposed on the interior face of each
arm 72. The locking element engagement feature 78 mates with a
complementary housing engagement feature 80 on the locking element
68, described in further detail below.
[0091] FIGS. 9 and 10 illustrate the locking element 68 in greater
detail. The locking element 68 is attachable to the housing 62
after the spinal rod 12 has been seated within the rod channel 64.
In the example presently described, the locking element 68
comprises a set screw having a housing engagement feature 80 and a
rod engagement insert 82. The housing engagement feature 80
complementarily engages the locking element engagement feature 78
of the upstanding arms 72. The rod engagement insert 82 is a block
of material sized and dimensioned to snugly fit within a recess 84
formed within the locking element 68 and having a convex surface 86
that forms the upper boundary of the rod channel 74 when the
locking element 68 is mated with the housing 62. The convex surface
86 is configured to engage the generally cylindrical spinal rod 12
and exert a force on the spinal rod 12 to enable the frictional
lock. By way of example, the locking element 38 is made of a rigid
material (e.g. titanium). Significantly, the rod engagement insert
82 of the instant example may be formed of a semi-rigid elastomeric
material that allows for some movement (e.g. vertical shifting,
axial rotation, pivoting, and/or translation) of the spinal rod 12
within the housing 62 while maintaining a frictional association
with the spinal rod 12 (and thus preventing unrestricted movement
of the rod). The rod engagement insert 82 is secured within the
recess 84 via a physical barrier (i.e. flange and lip interaction)
however other methods of securing the rod engagement insert 82
within the recess 84 are possible.
[0092] In use, after the spinal rod 12 has been seated within the
rod channel 74, the locking element 68 is inserted between the
upstanding arms 72 such that the housing engagement feature 80 on
the locking element 68 engages the locking element engagement
features 78 on each of the upstanding arms 72. The locking element
68 is then advanced via rotation to exert a force on the spinal rod
12 and frictionally lock the spinal rod 12 within the housing 62
(and between the locking element 68 and the rod seat 76). After
implantation, the semi-rigid nature of the elastomeric rod
engagement insert 82 will allow the construct to absorb some force
and experience some potential alignment correction that may occur
from natural shifting of the patient's body, thereby potentially
alleviating some conditions that may lead to junctional disease or
failure (e.g. PJK, DJK, etc.).
[0093] FIGS. 11-14 illustrate another example of a bone anchor
configured for use with the vertebral fixation system 10 described
above. By way of example, the bone anchor 90 is a fixed angle screw
having a housing 92 for capturing and locking therein a spinal rod
12, a shank 96 including a thread feature 96 suitable for stable
fixation to vertebral bone, and a locking element 98 configured for
locking the spinal rod 12 within the housing 92.
[0094] The housing 92 has a base 100 that mates (or is integrally
formed) with the shank 94 and a pair of upstanding arms 102
separated by and partially defining a rod channel 104 sized and
configured to receive the spinal rod 12 therein. The base includes
a recess 106 formed within the rod channel and configured to
receive a rod seat 108. The rod seat 108 is a block of material
sized and dimensioned to snugly fit within the recess 106 and
having a concave surface 110 that forms the lower portion of the
rod channel 104. The concave surface 110 is configured to engage
the generally cylindrical spinal rod 12 and provide a seat for the
spinal rod 12. Significantly, the rod seat 108 of the instant
example may be formed of a semi-rigid elastomeric material that
allows for some movement (e.g. vertical shifting, axial rotation,
pivoting, and/or translation) of the spinal rod 12 within the
housing 92 while maintaining a frictional association with the
spinal rod 12 (and thus preventing unrestricted movement of the
rod). The upstanding arms 102 include a locking element engagement
feature 112 disposed on the interior face of each arm 102. The
locking element engagement feature 112 mates with a complementary
housing engagement feature 114 on the locking element 98, described
in further detail below.
[0095] The locking element 98 is attachable to the housing 92 after
the spinal rod 12 has been seated within the rod channel 104. In
the example presently described, the locking element 98 comprises a
setscrew having a housing engagement feature 114 and a rod
engagement insert 116.
[0096] The housing engagement feature 114 complementarily engages
the locking element engagement feature 112 of the upstanding arms
102. The rod engagement insert 116 is a block of material sized and
dimensioned to snugly fit within a recess 118 formed within the
locking element 98 and having a convex surface 119 that forms the
upper boundary of the rod channel 104 when the locking element 98
is mated with the housing 92. The convex surface 119 is configured
to engage the generally cylindrical spinal rod 12 and exert a force
on the spinal rod 12 to enable the frictional lock. By way of
example, the locking element 98 is made of a rigid material (e.g.
titanium). Significantly, the rod engagement insert 116 of the
instant example may be formed of a semi-rigid elastomeric material
that allows for some movement (e.g. vertical shifting, axial
rotation, pivoting, and/or translation) of the spinal rod 12 within
the housing 92 while maintaining a frictional association with the
spinal rod 12 (and thus preventing unrestricted movement of the
rod). The rod engagement insert 116 is secured within the recess
118 via a physical barrier (i.e. flange and lip interaction)
however other methods of securing the rod engagement insert 116
within the recess 118 are possible.
[0097] In use, after the spinal rod 12 has been seated within the
rod channel 104, the locking element 98 is inserted between the
upstanding arms 102 such that the housing engagement feature 114 on
the locking element 98 engages the locking element engagement
features 112 on each of the upstanding arms 102. The locking
element 98 is then advanced via rotation to exert a force on the
spinal rod 12 and frictionally lock the spinal rod 12 within the
housing 92 (and between the locking element 98 and the rod seat
108). After implantation, the semi-rigid nature of both the
elastomeric rod seat 108 and the rod engagement insert 116 will
allow the construct to absorb some force and experience some
potential alignment correction that may occur from natural shifting
of the patient's body, thereby potentially alleviating some
conditions that may lead to junctional disease or failure (e.g.
PJK, DJK, etc.).
[0098] FIGS. 15-20 illustrate another example of a bone anchor
configured for use with the vertebral fixation system 10 described
above. By way of example, the bone anchor 120 is a polyaxial screw
having a housing 122 for capturing and locking therein a spinal rod
12, a shank 124 including a generally spherical head 126 and a
thread feature 128 suitable for stable fixation to vertebral bone,
a seat member 130, and a locking element 132 configured for locking
the spinal rod 12 within the housing 122.
[0099] The housing 122 has a base 134 that mates with the shank 124
and a pair of upstanding arms 136 separated by and partially
defining a rod channel 138 sized and configured to receive the
spinal rod 12 therein. The base 134 includes a recess 140 having a
concave surface sized and dimensioned to receive the spherical head
126 of the shank 124. The spherical head 126 is able to rotate and
pivot within the recess 140 such that the shank 124 may be disposed
at any number of a plurality of angles relative to the housing 122.
The upstanding arms 136 include a locking element engagement
feature 142 disposed on the interior face of each arm 136. The
locking element engagement feature 142 mates with a complementary
housing engagement feature 160 on the locking element 132,
described in further detail below.
[0100] The shank 124 further includes a driver recess 144
positioned at the top of the head 126 such that the driver recess
144 is accessible from the rod channel 138 prior to insertion of
the locking element 132. The driver recess 144 is configured to
engage a driver instrument (not shown) to enable implantation of
the bone anchor 120 into a vertebral bone.
[0101] Referring to FIGS. 19 and 20, the seat member 130 is
generally cylindrical in shape and has a lumen 146 extending
longitudinally therethrough to allow passage of a driver instrument
so that the driver instrument may engage the driver recess 144 of
the shank 124. The lower portion of the lumen 146 has a concave
surface 148 configured to receive and engage at least a portion of
the generally spherical head 126 of the shank 124. The seat member
130 also includes a pair of opposing concave recesses 150 on the
upper portion of the seat member 130. When properly assembled, the
concave recesses 150 are aligned with and form part of the rod
channel 138 for receiving the spinal rod 12.
[0102] The seat member 130 further includes a rod seat 152 disposed
within the upper portion of the lumen 146. The rod seat 152 is a
block of material sized and dimensioned to snugly fit within the
lumen 146 and having a pair of concave surfaces 154 that form part
of the lower portion of the rod channel 138. The concave surfaces
154 are configured to engage the generally cylindrical spinal rod
12 and provide a seat for the spinal rod 12. Significantly, the rod
seat 152 of the instant example may be formed of a semi-rigid
elastomeric material that allows for some movement (e.g. vertical
shifting, axial rotation, pivoting, and/or translation) of the
spinal rod 12 within the housing 122 while maintaining a frictional
association with the spinal rod 12 (and thus preventing
unrestricted movement of the rod). By way of example, the rod seat
152 is secured within the lumen 146 via a physical barrier
interaction (i.e. a flange 156 on the rod seat 152 that is received
within a recess 158 disposed within the lumen 146).
[0103] The locking element 132 is attachable to the housing 122
after the spinal rod 12 has been seated within the rod channel 138.
In the example presently described, the locking element 132
comprises a setscrew having a housing engagement feature 160 and a
rod engagement surface 162. The housing engagement feature 160
complementarily engages the locking element engagement feature 142
of the upstanding arms 136. The rod engagement surface 162 is
configured to engage the spinal rod 12 and may be planar, convex,
or concave. By way of example, the locking element 38 is made of a
rigid material (e.g. titanium).
[0104] In use, after the spinal rod 12 has been seated within the
rod channel 138, the locking element 132 is inserted between the
upstanding arms 136 such that the housing engagement feature 160 on
the locking element 132 engages the locking element engagement
features 142 on each of the upstanding arms 136. The locking
element 132 is then advanced via rotation to exert a force on the
spinal rod 12 and frictionally lock the spinal rod 12 within the
housing 122 (and between the locking element 132 and the rod seat
152). After implantation, the semi-rigid nature of the elastomeric
rod seat 152 will allow the construct to absorb some force and
experience some potential alignment correction that may occur from
natural shifting of the patient's body, thereby potentially
alleviating some conditions that may lead to junctional disease or
failure (e.g. PJK, DJK, etc.).
[0105] FIGS. 21-23 illustrate another example of a bone anchor
configured for use with the vertebral fixation system 10 described
above. By way of example, the bone anchor 170 is a polyaxial screw
having a housing 172 for capturing and locking therein a spinal rod
12, a shank 174 including a generally spherical head 176 and a
thread feature 178 suitable for stable fixation to vertebral bone,
a seat member 180, and a locking element 182 configured for locking
the spinal rod 12 within the housing 172.
[0106] The housing 172 has a base 184 that mates with the shank 174
and a pair of upstanding arms 186 separated by and partially
defining a rod channel 188 sized and configured to receive the
spinal rod 12 therein. The base 184 includes a recess 190 having a
concave surface sized and dimensioned to receive the spherical head
176 of the shank 174. The spherical head 176 is able to rotate and
pivot within the recess 190 such that the shank 174 may be disposed
at any number of a plurality of angles relative to the housing 172.
The upstanding arms 186 include a locking element engagement
feature 192 disposed on the interior face of each arm 186. The
locking element engagement feature 192 mates with a complementary
housing engagement feature 202 on the locking element 182,
described in further detail below.
[0107] The shank 174 further includes a driver recess 194
positioned at the top of the head 176 such that the driver recess
194 is accessible from the rod channel 138 prior to insertion of
the locking element 182. The driver recess 194 is configured to
engage a driver instrument (not shown) to enable implantation of
the bone anchor 170 into a vertebral bone.
[0108] The seat member 180 is generally cylindrical in shape and
has a lumen 146 extending longitudinally therethrough to allow
passage of a driver instrument so that the driver instrument may
engage the driver recess 194 of the shank 174. The lower portion of
the lumen 196 has a concave surface 198 configured to receive and
engage at least a portion of the generally spherical head 176 of
the shank 174. The seat member 180 also includes a rod seat 200 in
the form of a pair of opposing concave recesses on the upper
portion of the seat member 180. The concave surfaces 200 are
configured to engage the generally cylindrical spinal rod 12 and
provide a seat for the spinal rod 12.
[0109] The locking element 182 is attachable to the housing 172
after the spinal rod 12 has been seated within the rod channel 188.
In the example presently described, the locking element 182
comprises a setscrew having a housing engagement feature 202 and a
rod engagement insert 204. The housing engagement feature 202
complementarily engages the locking element engagement feature 192
of the upstanding arms 186. The rod engagement insert 204 is a
block of material sized and dimensioned to snugly fit within a
recess 206 formed within the locking element 182 and having a
convex surface 208 that forms the upper boundary of the rod channel
188 when the locking element 182 is mated with the housing 172. The
convex surface 208 is configured to engage the generally
cylindrical spinal rod 12 and exert a force on the spinal rod 12 to
enable the frictional lock. By way of example, the locking element
182 is made of a rigid material (e.g. titanium). Significantly, the
rod engagement insert 204 of the instant example may be formed of a
semi-rigid elastomeric material that allows for some movement (e.g.
vertical shifting, axial rotation, pivoting, and/or translation) of
the spinal rod 12 within the housing 172 while maintaining a
frictional association with the spinal rod 12 (and thus preventing
unrestricted movement of the rod). The rod engagement insert 204 is
secured within the recess 206 via a physical barrier (i.e. flange
and lip interaction) however other methods of securing the rod
engagement insert 204 within the recess 206 are possible.
[0110] In use, after the spinal rod 12 has been seated within the
rod channel 188, the locking element 182 is inserted between the
upstanding arms 186 such that the housing engagement feature 202 on
the locking element 182 engages the locking element engagement
features 192 on each of the upstanding arms 186. The locking
element 182 is then advanced via rotation to exert a force on the
spinal rod 12 and frictionally lock the spinal rod 12 within the
housing 172 (and between the locking element 182 and the rod seat
200). After implantation, the semi-rigid nature of the elastomeric
rod engagement insert 204 will allow the construct to absorb some
force and experience some potential alignment correction that may
occur from natural shifting of the patient's body, thereby
potentially alleviating some conditions that may lead to junctional
disease or failure (e.g. PJK, DJK, etc.).
[0111] FIGS. 24-27 illustrate another example of a bone anchor
configured for use with the vertebral fixation system 10 described
above. By way of example, the bone anchor 210 is a polyaxial screw
having a housing 212 for capturing and locking therein a spinal rod
12, a shank 214 including a generally spherical head 216 and a
thread feature 218 suitable for stable fixation to vertebral bone,
a seat member 220, and a locking element 222 configured for locking
the spinal rod 12 within the housing 212.
[0112] The housing 212 has a base 224 that mates with the shank 214
and a pair of upstanding arms 226 separated by and partially
defining a rod channel 228 sized and configured to receive the
spinal rod 12 therein. The base 224 includes a recess 230 having a
concave surface sized and dimensioned to receive the spherical head
216 of the shank 214. The spherical head 216 is able to rotate and
pivot within the recess 230 such that the shank 214 may be disposed
at any number of a plurality of angles relative to the housing 212.
The upstanding arms 226 include a locking element engagement
feature 232 disposed on the interior face of each arm 226. The
locking element engagement feature 232 mates with a complementary
housing engagement feature 246 on the locking element 222,
described in further detail below.
[0113] The shank 214 further includes a driver recess 234
positioned at the top of the head 216 such that the driver recess
234 is accessible from the rod channel 228 prior to insertion of
the locking element 222. The driver recess 234 is configured to
engage a driver instrument (not shown) to enable implantation of
the bone anchor 210 into a vertebral bone.
[0114] The seat member 220 is identical to the seat member 130
described in reference to FIGS. 19 and 20. The seat member 220 is
generally cylindrical in shape and has a lumen extending
longitudinally therethrough to allow passage of a driver instrument
so that the driver instrument may engage the driver recess 234 of
the shank 214. The lower portion of the lumen has a concave surface
238 configured to receive and engage at least a portion of the
generally spherical head 216 of the shank 214. The seat member 220
also includes a pair of opposing concave recesses on the upper
portion of the seat member. When properly assembled, the concave
recesses are aligned with and form part of the rod channel 228 for
receiving the spinal rod 12.
[0115] The seat member 220 further includes a rod seat 242 disposed
within the upper portion of the lumen. The rod seat 242 is a block
of material sized and dimensioned to snugly fit within the lumen
and having a pair of concave surfaces 244 that form part of the
lower portion of the rod channel 228. The concave surfaces 244 are
configured to engage the generally cylindrical spinal rod 12 and
provide a seat for the spinal rod 12. Significantly, the rod seat
242 of the instant example may be formed of a semi-rigid
elastomeric material that allows for some movement (e.g. vertical
shifting, axial rotation, pivoting, and/or translation) of the
spinal rod 12 within the housing 212 while maintaining a frictional
association with the spinal rod 12 (and thus preventing
unrestricted movement of the rod). By way of example, the rod seat
242 is secured within the lumen via a physical barrier interaction
(i.e. a flange on the rod seat that is received within a recess
disposed within the lumen).
[0116] The locking element 222 is attachable to the housing 212
after the spinal rod 12 has been seated within the rod channel 228.
In the example presently described, the locking element 222
comprises a setscrew having a housing engagement feature 246 and a
rod engagement insert 248. The housing engagement feature 246
complementarily engages the locking element engagement feature 232
of the upstanding arms 226. The rod engagement insert 248 is a
block of material sized and dimensioned to snugly fit within a
recess 250 formed within the locking element 222 and having a
convex surface 252 that forms the upper boundary of the rod channel
188 when the locking element 222 is mated with the housing 212. The
convex surface 252 is configured to engage the generally
cylindrical spinal rod 12 and exert a force on the spinal rod 12 to
enable the frictional lock. By way of example, the locking element
222 is made of a rigid material (e.g. titanium). Significantly, the
rod engagement insert 248 of the instant example may be formed of a
semi-rigid elastomeric material that allows for some movement (e.g.
vertical shifting, axial rotation, pivoting, and/or translation) of
the spinal rod 12 within the housing 212 while maintaining a
frictional association with the spinal rod 12 (and thus preventing
unrestricted movement of the rod). The rod engagement insert 248 is
secured within the recess 250 via a physical barrier (i.e. flange
and lip interaction) however other methods of securing the rod
engagement insert 248 within the recess 250 are possible.
[0117] In use, after the spinal rod 12 has been seated within the
rod channel 228, the locking element 222 is inserted between the
upstanding arms 226 such that the housing engagement feature 246 on
the locking element 222 engages the locking element engagement
features 232 on each of the upstanding arms 226. The locking
element 222 is then advanced via rotation to exert a force on the
spinal rod 12 and frictionally lock the spinal rod 12 within the
housing 212 (and between the locking element 222 and the rod seat
242). After implantation, the semi-rigid nature of the elastomeric
rod seat 242 and the elastomeric rod engagement insert 248 will
allow the construct to absorb some force and experience some
potential alignment correction that may occur from natural shifting
of the patient's body, thereby potentially alleviating some
conditions that may lead to junctional disease or failure (e.g.
PJK, DJK, etc.).
[0118] FIGS. 28-35 illustrate another example of a bone anchor
assembly configured for use with the vertebral fixation system 10
described above. By way of example, the bone anchor assembly 260
includes a bone anchor 262, a translation body 264, a rod-receiving
member 266, and a locking element 268. As will be explained below,
the bone anchor assembly 260 is semi-adjustable after implantation
(e.g. allows for controlled motion) in that the rod-receiving
member 266 has some freedom to translate and/or rotate relative to
the translation body 264 to accommodate natural shifting that may
occur. By way of example, FIGS. 28-30 illustrate the bone anchor
assembly 260 with the rod-receiving member 266 in three different
translational positions.
[0119] The bone anchor 262 extends generally perpendicularly from
the bottom surface of the translation body 264 and has a thread
feature 270 suitable for stable fixation to vertebral bone. The
translation body 264 has a generally elliptical footprint
(illustrated in FIG. 33) however other shapes are possible. The
translation body 264 has a top surface 272, a bottom surface 274,
and a translation surface 276 configured to engage the
rod-receiving member 266 and allow translation in a proximal-distal
direction. The top surface 272 is generally planar however other
shapes including but not limited to convex are possible. The top
surface 272 has an elongated recess 278 having a T-shaped
cross-section formed therein that limits the degree of translation.
By way of example, the elongated recess 278 may be generally
elliptical in shape but may also be tapered in that it is wider in
the center of the recess than it is at either end. This tapered
shaped functions to provide greater resistance to incremental
translation as the rod-receiving member 266 approaches the outer
ends of the recess 278 in either direction. The recess 278 further
includes a pair of overhangs 279 that give the recess 278 its
T-shaped cross-section and also function to retain the cylindrical
flange 288 of the rod-receiving member 266 within the recess 278.
The translation surface 276 comprises the bottom surface of the
elongated recess 278 and may be planar or slightly convex.
[0120] Referring to FIGS. 34 and 35, the rod-receiving member 266
includes a base 280 and a pair of upstanding arms 282 separated by
a rod channel 284. The base 280 includes a protrusion 286 extending
away from the base 280 and a cylindrical flange 288 positioned a
the end of the protrusion 286. The protrusion 286 has a generally
cylindrical shape and has a diameter that is less than the diameter
of the cylindrical flange 288. The result is that the protrusion
286 and flange 288 when taken together have a generally T-shaped
cross section. The protrusion 286 and flange 288 fit within the
recess 278 of the fixation body 264 and are configured to allow
multiple degrees of movement of the rod-receiving member 266
relative to the fixation body 264. More specifically, the
cylindrical shapes of both the protrusion 286 and flange 288 allow
axial rotation of the rod-receiving member, and a generally planar
bottom surface 290 of the flange 288 allows for smooth translation
of the flange 288 (and thus the rod-receiving member 266) within
the recess 264. The upper surface 290 of the base 280 is a concave,
semi-cylindrical surface having a generally arcuate cross-section.
The upper surface 290 forms the distal end of the rod channel 284
and forms a cradle that receives the spinal rod 12 during
implantation. The upstanding arms 282 are equipped with a locking
element engagement feature 292 disposed on the interior face of
each arm 282. The locking element engagement feature 292 mates with
a housing engagement feature 298 on the locking element 268.
[0121] The base 280 has a hollow lumen 294 formed therein and
configured to receive an elastomeric plug therein. In the example
shown in FIGS. 34 and 35, both the hollow lumen 294 and the
elastomeric plug 296 have generally cylindrical cross sections,
however other shapes are possible. The elastomeric plug 296 has a
length that is at least slightly greater than the length of the
hollow lumen 294 so that the ends of the elastomeric plug 296 are
in continuous contact with both the spinal rod 12 and the
translation surface 276 of the translation body 264. After
implantation, the semi-rigid nature of the elastomeric plug 296
will allow the construct to absorb some force and experience some
potential alignment correction that may occur from natural shifting
of the patient's body, thereby potentially alleviating some
conditions that may lead to junctional disease or failure (e.g.
PJK, DJK, etc.).
[0122] The locking element 268 is attachable to the upstanding arms
282 after the spinal rod 12 has been seated within the rod channel
284. In the example presently described, the locking element 268
comprises a setscrew having a housing engagement feature 298 and a
rod engagement surface 299. The housing engagement feature 298
complementarily engages the locking element engagement feature 292
of the upstanding arms 282. The rod engagement surface 299 is
configured to engage the spinal rod 12 and may be planar, convex,
or concave. By way of example, the locking element 268 is made of a
rigid material (e.g. titanium).
[0123] FIGS. 36-38 illustrate an example utilizing tethers
connected to bone anchors and/or rods to strengthen, reconstruct,
and/or otherwise emulate ligaments that may have been damaged or
removed during implantation of the vertebral fixation system 10.
For example, a tether connected to a bone anchor may be wrapped
around the facet, transverse process, lamina, rib and/or spinous
process to provide further stability to the construct. As another
example, a tether may be attached to a rod at or near the proximal
terminus of the vertebral fixation system 10 in lieu of bone screws
to alleviate or eliminate factors that may cause junctional disease
or failure (e.g. PJK, DJK, etc.).
[0124] FIG. 36 illustrates an example of a bone anchor 300 with an
attached tether suitable for use with the vertebral fixation system
10. By way of example, the bone anchor 300 may be either a fixed
angle screw or polyaxial screw. The bone anchor 300 includes a
housing 302 for capturing and locking therein a spinal rod 12, a
shank 304 including a thread feature 306 suitable for stable
fixation to vertebral bone, and a locking element 308 configured
for locking the spinal rod 12 within the housing 302. The bone
anchor 300 is substantially similar to the various examples of bone
anchors described throughout this disclosure such that repeat
description of the housing 302, shank 304, and locking element 308
beyond what is necessary to describe the additional tether feature
specific to this example embodiment is not necessary. It is to be
understood that any feature of any other example embodiment
described herein may be included in this (and any other) example
embodiment without reservation either alone or in combination.
[0125] The housing 302 has a pair of upstanding arms 310 separated
by and partially defining a rod channel sized and configured to
receive the spinal rod 12 therein. At least one of the upstanding
arms 310 includes a tether connector 312 extending outwardly away
from the arm 310 and configured to fixedly receive a tether 314
therein. By way of example, the tether connector 312 comprises a
post member having a lumen 316 formed therein that is sized to
receive at least a portion of the tether 314. The tether 314 may be
formed of any material suitable for medical use. For example, the
tether may be made from allograft tendon, autograft tendon,
braided, woven, or embroidered polyethylene, braided, woven, or
embroidered polyester, PEEK, or PEKK. In some instances the tether
314 may be formed of elastic material. The tether 314 of the
instant example has a stop element 318 attached to or otherwise
forming the proximal end of the tether 314. The stop element 318
buffers against the tether connector 312 and acts as a physical
barrier to prevent the proximal end of the tether 314 from passing
through the lumen 316. In this way the tether 314 is secured to the
tether connector 312. By way of example, the stop element may be
formed by a knot, a clamp, or a crimp. Additionally the stop
element may be in the form of a connection loop created when the
proximal end of the tether is reattached to itself (e.g. via clamp,
crimp, adhesive, braiding, weaving, and/or embroidery) distal of
the tether connector 312. Other attachment methods of securing the
tether 314 to the tether connector 312 are possible, including but
not limited to adhesive, spot welding, set screw, and the like. The
tether 314 may be formed of any length necessary to secure the bone
anchor 300 to surrounding bone structure. By way of example, the
tether may be wrapped around (or, through a hole formed therein)
one or more of a lamina(s), transverse process(s), spinous
process(s), and rib(s). After wrapping around the bone, the tether
may be attached back to itself (e.g. via knot, clamp, crimp, etc. .
. . ), a second tether connector on the housing 302, or a tether
connector on another bone anchor (e.g. a contralateral anchor) or
alternate connector, such as the rod connector 320 described below.
Alternatively, the tether may be anchored directly to the
lamina(s), transverse process(s), spinous process(s), or rib(s)
(for example, with a suture anchor, staple, or similar device).
[0126] FIG. 37 illustrates an example of a rod attachment 320 with
attached tether suitable for use with the vertebral fixation system
10. The rod attachment 320 includes a housing 322 having a lumen
324 extending longitudinally therethrough configured to receive at
least a portion of the spinal rod 12. By way of example, the
housing 322 includes one side comprising a generally planar surface
326 and another side comprising a generally arcuate surface 328.
The generally planar surface 326 includes at least one aperture 330
for receiving a locking element 332. In the instant example, the
generally planar surface 326 includes a pair of apertures 330 and
thus the rod attachment 320 has a pair of locking elements 332. The
locking elements 332 are substantially similar to the locking
elements described in the various examples above and further
description need not be repeated. The rod attachment 320 further
includes a tether connector 334 extending outwardly and configured
to fixedly receive a tether 336 therein. The tether connector 334
comprises a post member having a lumen 335 formed therein that is
sized to receive at least a portion of the tether 336. The tether
336 of the instant example has a stop element 338 attached to or
otherwise forming the proximal end of the tether 336. By way of
example, the stop element may be formed by a knot, a clamp, or a
crimp. Additionally the stop element 338 may be in the form of a
connection loop created when the proximal end of the tether is
reattached to itself (e.g. via clamp, crimp, adhesive, braiding,
weaving, and/or embroidery) distal of the tether connector 334.
Other attachment methods of securing the tether 336 to the tether
connector 334 are possible, including but not limited to adhesive,
spot welding, set screw, and the like. The tether 336 may be formed
of any length necessary to secure the rod, via rod connector 320,
to surrounding bone structure. By way of example, the tether may be
wrapped around (or, through a hole formed therein) one or more of a
lamina(s), transverse process(s), spinous process(s), and rib(s).
After wrapping around the bone, the tether may be attached back to
itself (e.g. via knot, clamp, crimp, etc. . . . ), a second tether
connector on the housing 322, or a tether connector on another bone
anchor or rod connector connector, such as the rod connector 320
described below. Alternatively, the tether may be anchored directly
to the lamina(s), transverse process(s), spinous process(s), or
rib(s) (for example, with a suture anchor, staple, or similar
device).
[0127] FIG. 38 illustrates the bone anchor 300 and rod attachment
320 in use after implantation in a human spine. By way of example,
as shown the tethers are wrapped around a lamina, transverse
process, and a spinous process. It will be appreciated that the
tether may be wrapped around one of, or any combination of, one or
more lamina, transverse processes, spinous processes, and ribs.
[0128] FIGS. 39-44 illustrate another example of a bone anchor 340
suitable for use with the vertebral fixation system 10. In the
embodiment shown by way of example in the attached Figs., the bone
anchor 340 is substantially similar to any of the polyaxial bone
screw example embodiments described above such that features
described above may be applied to this example without reservation
either alone or in combination. The bone anchor 340 includes a
housing 342 for capturing and locking therein a spinal rod 12, a
shank 344 including a generally spherical head 346 and a thread
feature 348 suitable for stable fixation to vertebral bone, a seat
member 350, and a locking element 352 configured for locking the
spinal rod 12 within the housing 342. The bone anchor 340 further
includes a collar 354 positioned at the top of the shank 344 just
below the head 346 such that the collar 354 is flushly engaged with
the housing 342. By way of example only, the collar 354 may be
composed of an elastomeric material and may also have a spring 356
disposed therein that is biased toward the housing 342. The collar
354 functions to convert the otherwise fixed relationship between
shank and head upon locking of a rod with a setscrew into a limited
range permanent polyaxial bone screw. Once the bone anchor 340 has
been implanted into the spine as a part of the vertebral fixation
system 10 it may experience realignment pressure (of the type that
causes DJK and PJK). Under such a circumstance, the elastomeric
collar 354 and/or spring 356 are capable of allowing controlled
movement of the housing 342, for example adjustment of the angle
formed between the housing member 342 and shank 344, controlled
minimal translation along the spinal rod 12, and/or further
compression of the collar 354 if adjustment is needed in that
direction.
[0129] In some instances it may be beneficial if the spinal rod
itself was capable of compression, distraction, and/or rotation in
response to realignment pressure. FIGS. 42-44 illustrate the bone
anchor 340 used with one example of a flexible rod 790. By way of
example, the flexible rod 790 includes an interior rod 792, a
spring coil 794, and an elastomeric sheath 796. The interior rod
792 has a narrow diameter and may be composed of any material that
allows for some flexibility (e.g. Nitinol, PEEK, PEKK, etc.). The
spring coil 794 is disposed around the interior rod 792 and may
extend beyond the proximal terminus of the interior rod 792. The
elastomeric sheath 796 is disposed around the interior rod 792 and
the spring coil 794 and may extend the same length as the spring
coil 794. The interior rod 792 gives the flexible rod 790 some
rigidity, while the spring coil 794 functions to allow for
compression, distraction and rotational movement of the flexible
rod 790. The elastomeric sheath 796 holds the spring coil 794 in
place and also allows for controlled compression, distraction, and
rotational movement of the flexible rod 790. It should be noted
that the locking element 352 locks the flexible rod 790 within the
housing 342 but does not exert pressure to the point of compressing
the spring coil 794 within the flexible rod 790.
[0130] FIGS. 45-48 illustrate an example of a transition apparatus
360 configured for use with the vertebral fixation system 10
described herein. The purpose of the transition apparatus 360 is to
gradually reduce the rigidity of the fixation construct as it
transitions from instrumented to non-instrumented vertebra. One
advantage associated with the transition apparatus 360 is it
reduces the need for muscle stripping along the patient's back and
therefore may leave intact those anatomical structures that
naturally help to prevent outcomes such as DJK or PJK.
[0131] FIG. 45 illustrates the transition apparatus 360 implanted
in a segment of the spine. The transition apparatus 360 includes a
bone anchor 362, one or more bone hooks 364, and a flexible cord
366. The bone anchor 362 includes a housing 368 for receiving the
spinal rod 12, a shank 370, and a locking element 372 for securing
the spinal rod 12 within the housing 368. The bone anchor 362 may
be one of any of the bone screw example embodiments described above
such that any and all features described above may be applied to
this example without reservation either alone or in combination,
and further discussion of the bone screw 362 is not necessary.
[0132] The bone hook 364 includes a housing 374, a generally curved
hook member 376 extending from the base of the housing 374, and a
locking element 378. The housing 374 includes a pair of upstanding
arms 380 separated by and forming part of a rod channel 382. The
upstanding arms 380 include a locking element engagement feature
384 disposed on the interior face of each arm 380. The locking
element engagement feature 384 mates with a complementary housing
engagement feature 386 on the locking element 378 to secure the
flexible cord 366 within the rod channel 382. The generally curved
hook member 376 is has a concave curvature that forms a cavity 386
dimensioned to receive a bone segment. By way of example only, the
bone hooks 364 of the present example are configured to be used
with rib bone, however other configurations are possible.
[0133] The flexible cord 366 may be composed of any material
medically suitable for implantation into a human and sufficiently
flexible to serve as a transition medium, including but not limited
to autograft tendon, allograft tendon, braided polyethylene, PEEK,
and PEKK. The flexible cord 366 is secured to the distal end of the
spinal rod 12 via an attachment member 388.
[0134] In use, the bone anchor 362 is implanted into the
proximal-most fully instrumented vertebral level V.sub.1. The bone
anchor 362 may have one or more of the features described above
(e.g. elastomeric inserts in one or more of the rod seat and
locking element, flexible collar, and the like). The spinal rod 12
terminates just proximally of the bone anchor 362 and transitions
to a flexible cord 366. The path of the flexible cord 366 is
directed laterally away from the spinal column and continues along
a path determined by the placement of the bone hooks 364. For
example, a first bone hook 364 may be secured to a rib R.sub.1
associated with the first non-instrumented vertebral body V.sub.2.
A second bone hook 364 may be secured to a rib R.sub.2 associated
with the second non-instrumented vertebral body V.sub.3. Since the
cord path is away from the spine, less muscle tissue would need to
be disturbed. And since the flexible cord 366 is flexible, it may
be better suited to handle alignment shifts than a rigid
construct.
[0135] FIGS. 49-56 illustrate another example of a transition
apparatus configured for use with the vertebral fixation system 10
described herein. Transition apparatus 390 includes a housing 392
that generally has the form of a rectangular block having a leading
surface 394, a trailing surface 396, a top surface 398, and a
bottom surface 400, a first rod channel 402, a second rod channel
404, a first locking element 406, and a second locking element 408.
The first rod channel 402 is sized and dimensioned to receive the
proximal end of the spinal rod 12. The second rod channel 404 is
configured to receive the distal end of a transition rod 410. The
transition rod 410 is generally more flexible than the spinal rod
12 and serves to transitionally reduce the strain associated with
the proximal terminus of the vertebral fixation system 10. The
transition rod 410 may be composed of any suitable medical grade
material capable of establishing a flexible connection, including
but not limited to plastics (e.g. PEEK) or flexible metal (e.g.
Nitinol). Additionally, the transition rod 410 may be in the form
of a cylindrically shaped rod, an oval shape, a fluted
configuration, a cord, or a tether.
[0136] The top surface 398 further includes a pair of apertures 412
for receiving the locking elements 406, 408 therein. The apertures
412 each have a locking element engagement feature 414 configured
to engage the corresponding housing engagement features of the
locking elements 406, 408. When inserted in the apertures 412, the
locking elements 406, 408 are able to contact and lock in place the
spinal rod 12 and transition rod 410, respectively.
[0137] The transition apparatus 390 further includes a pair of
buffer elements 416 attached to the proximal end of the spinal rod
12, with one buffer element 416 attached to the spinal rod 12 on
either side of the housing 392. The buffer element 416 includes a
spring 418 or block of elastomeric material (not pictured)
positioned within a sleeve 420. Locking rings 422 are provided
within circumferential grooves 424 formed in the spinal rod 12 to
provide a physical barrier for the buffer element 416 to ensure the
buffer element 416 remains in place.
[0138] The first locking element 406 is attachable to the housing
392 after the spinal rod 12 has been seated within the rod channel
402. In the example shown in FIG. 55, the locking element 406
comprises a setscrew having a housing engagement feature 426 and a
rod engagement surface 428. The housing engagement feature 426
complementarily engages the locking element engagement feature 414
of the housing 392. The rod engagement surface 428 is configured to
engage the spinal rod 12 and may be planar, convex, or concave. By
way of example, the locking element 406 is made of a rigid material
(e.g. titanium). In the example shown in FIG. 56, the locking
element 406 includes a rod engagement insert 430 comprising a block
of material sized and dimensioned to snugly fit within a recess
(not shown) formed within the locking element 406 and having a
convex surface 432 that forms the upper boundary of the rod channel
402 when the locking element 406 is mated with the housing 392. The
convex surface 432 is configured to engage the generally
cylindrical spinal rod 12 and exert a force on the spinal rod 12 to
enable the frictional lock. By way of example, the locking element
406 is made of a rigid material (e.g. titanium). Significantly, the
rod engagement insert 430 of the instant example may be formed of a
semi-rigid elastomeric material that allows for some movement (e.g.
vertical shifting, axial rotation, pivoting, and/or translation) of
the spinal rod 12 within the housing 392 while maintaining a
frictional association with the spinal rod 12 (and thus preventing
unrestricted movement of the rod). The rod engagement insert may be
configured such that the limited movement occurs only upon
surpassing a threshold pressure.
[0139] The second locking element 408 is attachable to the housing
392 after the transition rod 410 has been seated within the rod
channel 404. The locking element 408 comprises a setscrew having a
housing engagement feature 434 and a rod engagement surface 436.
The housing engagement feature 434 complementarily engages the
locking element engagement feature 414 of the housing 392. The rod
engagement surface 436 is configured to engage the spinal rod 12
and may be planar, convex, or concave. By way of example, the
locking element 408 is made of a rigid material (e.g.
titanium).
[0140] The buffer element 416 allows for controlled
translation/shifting of the spinal rod 12 within the housing 392
which will allow the construct to absorb some force and experience
some potential alignment correction that may occur from natural
shifting of the patient's body, thereby potentially alleviating
some conditions that may lead to junctional disease or failure
(e.g. PJK, DJK, etc.).
[0141] FIGS. 57-61 illustrate another example of a transition
apparatus configured for use with the vertebral fixation system 10.
The transition apparatus 440 of the present example generally
comprises a parallel rod connector with multiple degrees of freedom
of movement. The transition apparatus 440 includes a first housing
442 configured for receiving the spinal rod 12 and a second housing
444 configured for receiving a transition rod 446. The first
housing 442 and second housing 444 are connected via a pivot
connector 448. The first housing 442 is offset from the second
housing 444 such that a longitudinal axis extending through the
first rod channel 450 is parallel to, but not aligned with, a
longitudinal axis extending through the second rod channel 460.
[0142] The first housing includes a first rod channel 450 extending
therethrough that is sized and configured to receive the proximal
portion of the spinal rod 12. The rod channel 450 has an elliptical
cross-section to allow for some constrained motion of the spinal
rod 12 within the rod channel 450 after implantation. The first
housing 442 further includes an aperture 452 adjacent the rod
channel 450 for receiving a locking element 454. The aperture 452
includes a locking element engagement feature 456 configured to
engage the corresponding housing engagement feature 458 of the
locking element 454. When inserted in the aperture 452, the locking
element 454 is able to contact and lock in place the spinal rod 12
while allowing for some controlled movement within the rod channel
450. The locking element 454 comprises a setscrew having a housing
engagement feature 458 and a rod engagement surface. The housing
engagement feature 458 that complementarily engages the locking
element engagement feature 456 of the first housing 442. The rod
engagement surface is configured to engage the spinal rod 12 and
may be planar, convex, or concave. Although not shown, the locking
element 454 may alternatively be equipped with a rod engaging
insert comprising a block of elastomeric material (for example) as
shown and described in various example embodiments disclosed
above.
[0143] The second housing 444 includes a second rod channel 460
extending therethrough that is sized and configured to receive a
distal portion of the transition rod 446. The rod channel 460 has
an elliptical cross-section to allow for some constrained motion of
the transition rod 446 within the rod channel 460 after
implantation. The second housing 444 further includes an aperture
462 adjacent the rod channel 460 for receiving a locking element
464. The aperture 462 includes a locking element engagement feature
466 configured to engage the corresponding housing engagement
feature 468 of the locking element 464. When inserted in the
aperture 462, the locking element 464 is able to contact and lock
in place the transition rod 446 while allowing for some controlled
movement within the rod channel 460. The locking element 464
comprises a setscrew having a housing engagement feature 468 and a
rod engagement surface. The housing engagement feature 468
complementarily engages the locking element engagement feature 466
of the first housing 462. The rod engagement surface is configured
to engage the transition rod 446 and may be planar, convex, or
concave.
[0144] The pivot connector 448 comprises a generally cylindrical
member including a first end flange 470, a second end flange 472,
and a central flange 474. The first end flange 470 is configured to
be received within a recess 476 formed in the first housing 442.
The second end flange 472 is configured to be received within a
recess 478 formed in the second housing 444. The central flange 474
is positioned between the first and second housings 442, 444 when
assembled and acts as a washer. The first and second housings 442,
444 are allowed to pivot relative to one another. This pivoting
ability may be controlled or partially restricted but is not
locked.
[0145] FIGS. 62-64 illustrate another example of a transition
apparatus configured for use with the vertebral fixation system 10.
The transition apparatus 480 of the present example generally
comprises an inline rod connector with multiple degrees of freedom
of movement. The transition apparatus 480 includes a first housing
482 configured for receiving the spinal rod 12 and a second housing
484 configured for receiving a transition rod 486. The first
housing 482 and second housing 484 are connected via a pivot
connector 488. The first housing 482 is inline with the second
housing 484 such that a longitudinal axis extending through the
first rod channel 490 is axially aligned with a longitudinal axis
extending through the second rod channel 500.
[0146] The first housing includes a first rod channel 490 extending
therethrough that is sized and configured to receive the proximal
portion of the spinal rod 12. The rod channel 490 has an elliptical
cross-section to allow for some constrained motion of the spinal
rod 12 within the rod channel 490 after implantation. The first
housing 482 further includes an aperture 492 adjacent the rod
channel 490 for receiving a locking element 494. The aperture 492
includes a locking element engagement feature 496 configured to
engage the corresponding housing engagement feature 498 of the
locking element 494. When inserted in the aperture 492, the locking
element 494 is able to contact and lock in place the spinal rod 12
while allowing for some controlled movement within the rod channel
490. The locking element 494 comprises a setscrew having a housing
engagement feature 498 and a rod engagement surface. The housing
engagement feature 498 complementarily engages the locking element
engagement feature 496 of the first housing 482. The rod engagement
surface is configured to engage the spinal rod 12 and may be
planar, convex, or concave. Although not shown, the locking element
494 may alternatively be equipped with a rod engaging insert
comprising a block of elastomeric material (for example) as shown
and described in various example embodiments disclosed above.
[0147] The second housing 484 includes a second rod channel 500
extending therethrough that is sized and configured to receive a
distal portion of the transition rod 486. The rod channel 500 has
an elliptical cross-section to allow for some constrained motion of
the transition rod 486 within the rod channel 500 after
implantation. The second housing 484 further includes an aperture
502 adjacent the rod channel 500 for receiving a locking element
504. The aperture 502 includes a locking element engagement feature
506 configured to engage the corresponding housing engagement
feature 508 of the locking element 504. When inserted in the
aperture 502, the locking element 504 is able to contact and lock
in place the transition rod 486 while allowing for some controlled
movement within the rod channel 500. The locking element 504
comprises a setscrew having a housing engagement feature 508 and a
rod engagement surface. The housing engagement feature 508
complementarily engages the locking element engagement feature 506
of the first housing 502. The rod engagement surface is configured
to engage the transition rod 486 and may be planar, convex, or
concave.
[0148] The pivot connector 488 comprises a generally cylindrical
member including a first end flange 510, a second end flange 512,
and a central flange 514. The first end flange 510 is configured to
be received within a recess 516 formed in the first housing 482.
The first end flange 510 may be equipped with an elastomeric
coating 511 that allows for restrained translational movement of
the first end flange 510 within the recess 516. The second end
flange 512 is configured to be received within a recess 518 formed
in the second housing 484. The second end flange 512 may be
equipped with an elastomeric coating 513 that allows for restrained
translational movement of the second end flange 512 within the
recess 518. The central flange 514 is positioned between the first
and second housings 482, 484 when assembled and acts as a washer.
The first and second housings 482, 484 are allowed to pivot
relative to one another. This pivoting ability may be controlled
but is not locked.
[0149] FIGS. 65-68 illustrate an example of another type of bone
anchor configured for use with the vertebral fixation system 10.
Generally, the bone anchor 520 is configured to attach to a bone
structure (e.g. a transverse process TP.sub.1 or lamina of vertebra
V.sub.1) without puncturing or otherwise invading the bone. The
bone anchor 520 may be used with the spinal rod 12 or one of the
several examples of flexible transition rod (e.g. PEEK, cable)
disclosed above.
[0150] The bone anchor 520 includes a housing 522, an attachment
flange 524 extending from the base of the housing 522, and a
locking element 526. The housing 522 includes a pair of upstanding
arms 530 separated by and forming part of a rod channel 532. The
upstanding arms 530 include a locking element engagement feature
534 disposed on the interior face of each arm 530. The locking
element engagement feature 534 mates with a complementary housing
engagement feature 536 on the locking element 526 to secure the
transition rod within the rod channel 532. The attachment flange
524 has a concave first portion 538 extending away from the housing
522 and a generally planar second portion 540 adjacent the first
portion 538. The concave first portion 538 and generally planar
second portion 540 together form a cavity 542 (along with the
bottom face of the housing 522) dimensioned to receive a bone
segment. The second portion 540 is at least slightly flexible so
that it may accommodate different sizes of bone but also so that it
may experience some post-surgical adjustment without dislodging
from the bone. This flexibility may be achieved by varying the
thickness of the material or by using more flexible/elastic
materials in the manufacture of the flange 524. By way of example
only, the bone anchor 520 of the present example is sized and
configured to be used with transverse process bone, however other
configurations are possible.
[0151] At least one of the upstanding arms 530 includes a tether
connector 544 extending outwardly away from the arm 530 and
configured to fixedly receive a tether 546 therein. By way of
example, the tether connector 544 comprises a post member having a
lumen 545 formed therein that is sized to receive at least a
portion of the tether 546. The tether 546 may be formed of any
material suitable for medical use, including but not limited to
allograft tendon, autograft tendon, braided polyethylene, PEEK, or
PEKK. In some instances the tether 546 may be formed of elastic
material. The tether 546 may be formed of any length necessary to
secure the bone anchor 520 to surrounding bone by wrapping around
the bone. The tether 546 of the instant example has a stop element
548 is attached to or otherwise forms the proximal end of the
tether 546. The stop element 548 buffers against the tether
connector 544 and acts as a physical barrier to prevent the
proximal end of the tether 546 from passing through the lumen 545.
In this way the tether 546 is secured to the tether connector 544.
Other attachment methods of securing the tether 546 to the tether
connector 544 are possible, including but not limited to adhesive,
spot welding, and the like.
[0152] The locking element 526 may be any of the previously
described locking element examples disclosed herein. The locking
element 526 may or may not be equipped with a block of elastomeric
material, depending on the type of rod element that is secured in
the rod channel 532 by the locking element 526.
[0153] FIGS. 69-72 illustrate another example of a non-screw bone
anchor configured for use with the vertebral fixation system 10.
The bone anchor 550 of the instant example generally comprises a
clamp-type mechanism suitable for attachment to a rib bone. The
bone anchor 550 has includes a rib clamp 552, a connecting rod 554,
and a rod connector 556. The rib clamp 552 includes a first clamp
member 558 and a second clamp member 560 that are translationally
connected to each other.
[0154] The first clamp member 558 has an elongated generally
rectangular base 561 having a top side 562 and a bottom side 564.
The top side 562 has a housing 566 positioned on a first end of the
base 561 and protruding away from the top side 562. The housing 566
includes a rod hole 568 configured to receive the connecting rod
554 and a locking element 570 for securing the connecting rod 554
to the housing 566. The bottom side 564 includes an elongated
translation recess 572 and a curved flange 574. The translation
recess 572 is formed within the bottom side 564 on the first end of
the base 561 (underneath the housing 566) and is configured to
slideably receive the translation arm 580 of the second clamp
member 560. The curved flange 574 is positioned on the second end
of the base 561 and extends away from the bottom side 564 before
curving inward (i.e. toward the second clamp member 560). The
bottom side 564 and curved flange 574 together form a cavity 576
sized and configured to receive at least a portion of a rib
bone.
[0155] The second clamp member 560 includes a base 578 and a
translation arm 580 extending laterally from the base 578. The
translation arm 580 mates with the translation recess 572 of the
first clamp member 558 and is capable of translation within the
recess to allow the rib clamp 552 to be secured to a bone. The
second clamp member 560 further includes a curved flange 582 that
extends away from the bottom side of the second clamp member 560
before curving inward (i.e. toward the first clamp member 558). The
translation arm 580 and curved flange 582 together from a cavity
584 sized and configured to receive at least a portion of a rib
bone.
[0156] The rod connector 556 has a base and a pair of upstanding
arms 586 that define a rod channel in between. The rod channel is
configured to receive the spinal rod 12 or a transition rod (e.g.
any of the transition rod types described herein). The rod
connector 556 further has a locking element 588 (e.g. any of the
locking elements described herein) configured to secure the rod
connector 556 to the spinal rod 12 (or transition rod). The
connecting rod 554 extends laterally from one of the upstanding
arms 586.
[0157] The bone anchor 550 has multiple articulating connections to
help absorb force and allow controlled movement after implantation.
One articulating connection is between the rod connector 556 and
the spinal rod 12. This is much the same as the interaction between
the spinal rod and various examples of bone screws described above.
Another articulating connection is between the connecting rod 554
and the rib clamp 552. Thus slight shifting can occur without
causing dislodgement of the bone anchor 550.
[0158] FIGS. 73-76 illustrate an alternative example of a rib clamp
for use with the bone anchor 550. The rib clamp 590 of the instant
example is substantially similar to the rib clamp 552 described
above with the significant difference being the moveable housing
595 as will be described below. The rib clamp 590 includes a first
clamp member 592 and a second clamp member 594 that are
translationally connected to each other, and a housing 595 for
receiving the connecting rod 554.
[0159] The first clamp member 592 has an elongated generally
rectangular base 596 having a top side 598 and a bottom side 599.
The top side 598 has a pedestal 600 positioned on a first end of
the base 596 and protruding away from the top side 598. The
pedestal 600 includes a first translation recess 602 having a
length dimension extending parallel to the longitudinal axis of the
rib clamp 590. The first translation recess 602 is configured to
receive the lower flange 610 of the housing 595. The housing 595
has a base 604 and a pair of upstanding arms 606 separated by and
partially defining a rod channel 608 sized and configured to
receive the connecting rod 554 therein. The housing 595 further
includes a lower flange 610 that slideably mates with the first
translation recess 602 to connect the housing 595 to the first
clamp member 592. A locking element 612 (e.g. any of the setscrew
style locking elements described herein) mates with the housing 595
to secure the connecting rod 554 to the housing 595.
[0160] The bottom side 599 includes an elongated translation recess
614 and a curved flange 616. The translation recess 614 is formed
within the bottom side 599 on the first end of the base 596
(underneath the housing 566) and is configured to slideably receive
the translation arm 580 of the second clamp member 594. The curved
flange 616 is positioned on the second end of the base 596 and
extends away from the bottom side 599 before curving inward (i.e.
toward the second clamp member 594). The bottom side 599 and curved
flange 616 together form a cavity 618 sized and configured to
receive at least a portion of a rib bone.
[0161] The second clamp member 594 includes a base 620 and a
translation arm 622 extending laterally from the base 620. The
translation arm 622 mates with the translation recess 614 of the
first clamp member 592 and is capable of translation within the
recess to allow the rib clamp 590 to be secured to a bone. The
second clamp member 594 further includes a curved flange 624 that
extends away from the bottom side of the second clamp member 594
before curving inward (i.e. toward the first clamp member 592). The
translation arm 622 and curved flange 624 together from a cavity
584 sized and configured to receive at least a portion of a rib
bone.
[0162] The rod connector 556 has a base and a pair of upstanding
arms 586 that define a rod channel in between. The rod channel is
configured to receive the spinal rod 12 or a transition rod (e.g.
any of the transition rod types described herein). The rod
connector 556 further has a locking element 588 (e.g. any of the
locking elements described herein) configured to secure the rod
connector 556 to the spinal rod 12 (or transition rod). The
connecting rod 554 extends laterally from one of the upstanding
arms 586.
[0163] The bone anchor 550 has multiple articulating connections to
help absorb force and allow controlled movement after implantation.
One articulating connection is between the rod connector 556 and
the spinal rod 12. This is much the same as the interaction between
the spinal rod and various examples of bone screws described above.
Another articulating connection is between the connecting rod 554
and the rib clamp 590. Thus slight shifting can occur without
causing dislodgement of the bone anchor 550.
[0164] FIGS. 77-81 illustrate another example of a non-screw bone
anchor configured for use with the vertebral fixation system 10.
The bone anchor 630 of the instant example generally comprises a
clamp-type mechanism suitable for attachment to a lamina or
transverse process or spinous process bone or a combination
thereof. The bone anchor 630 includes a first clamp member 632 and
a second clamp member 634 that are translationally mated with each
other.
[0165] The first clamp member 632 has an elongated base 636 having
a top side 638 and a bottom side 640. The top side 638 has a
housing 642 positioned on a first end of the base 636 and
protruding away from the top side 638. The housing 642 has a base
644 and a pair of upstanding arms 646 separated by and partially
defining a rod channel 648 sized and configured to receive the
spinal rod 12 (or transition rod) therein. By way of example, the
housing 642 further includes a lower flange 650 that mates with a
first recess 652 formed in the top side 638 to connect the housing
642 to the first clamp member 632. A locking element 654 (e.g. any
of the setscrew style locking elements described herein) mates with
the housing 642 to secure the rod 12 to the housing 642. The top
side 638 further includes a second recess 655 formed on the second
end of the base 636 configured to slideably receive the translation
arm 662 of the second clamp member 634. The bottom side 640
includes a flange 656 positioned on the first end of the base 636
(underneath the housing 642) and extending away from the bottom
side 640 before curving inward (i.e. toward the second clamp member
634). The bottom side 640 and flange 656 together form a cavity 658
sized and configured to receive at least a portion of a lamina or
transverse process bone.
[0166] The second clamp member 634 includes a base 660 and a
translation arm 662 extending laterally from the base 660. The
translation arm 662 mates with the second recess 655 of the first
clamp member 632 and is capable of translation within the recess to
allow the bone anchor 630 to be secured to a bone. The second clamp
member 634 also includes a housing 642 with locking element 654
that are identical to the same elements described in relation to
the first clamp member 632. The second clamp member 634 further
includes a flange 664 that extends away from the bottom side of the
second clamp member 634 before curving inward (i.e. toward the
first clamp member 632). The translation arm 662 and flange 664
together from a cavity 666 sized and configured to receive at least
a portion of a lamina or transverse process bone.
[0167] The prior examples described herein have sought to address
the need for reducing or preventing the occurrence of junctional
disease and failures through instrumentation that aims to alleviate
stress on the proximal and/or distal termini of multi-level spinal
fixation systems. Another way to limit flexion in the proximal
and/or distal instrumented vertebrae is to create physical barriers
or countermeasures that either prevent or exert a counterforce to
reverse the kyphosis. One example of such a physical barrier is a
rod bumper that may be inserted between a bone anchor and spinal
rod, and extends a short distance distally along the spinal rod. As
flexion associated with kyphosis occurs and the upper vertebra
falls forward, the bumper pushes backwards on the spinal rod. In
response, the spinal rod exerts a return force on the bumper, which
then causes the upper vertebra to return to a more normal position.
FIGS. 82-86 illustrate one example of a bone anchor 670 with
associated rod bumper 672 that may be employed as a terminal anchor
in a fixation construct. The bone anchor 670 is shown by way of
example as a pedicle screw with a tulip and lock screw, however the
rod bumper may be used with other fixation hardware.
[0168] By way of example, the bone anchor 670 includes a housing
674, threaded shank 676, and locking element 678. The housing has a
base 680 and a pair of upstanding arms 682 that form the rod
channel. The locking element 678 may be any of the previously
described examples of locking elements. A rod bumper 672 maybe be
attached to the housing 674 or one end of may be inserted into the
rod channel between the housing 674 and spinal rod 12. The rod
bumper 672 has a concave rod engaging surface 684 so as to reduce
the profile of the spinal fixation system after implantation and
prior to the occurrence of flexion.
[0169] FIGS. 87-91 illustrate another example of a bone anchor and
rod bumper combination configured for use with cords or other
non-traditional transition rods. The bone anchor 690 is shown by
way of example as a pedicle screw with a tulip and lock screw,
however the rod bumper may be used with other fixation
hardware.
[0170] By way of example, the bone anchor 690 includes a housing
692, threaded shank 694, and locking element 696. The housing has a
base 698 and a pair of upstanding arms 700 that form the rod
channel. The locking element 696 may be any of the previously
described examples of locking elements. A rod bumper 702 maybe be
attached to the housing 692 or one end of may be inserted into the
rod channel between the housing 692 and transition cable rod 701.
The rod bumper 702 is has an elongated body 704 with a concave rod
engaging surface 706 to reduce the profile of the spinal fixation
system after implantation and prior to the occurrence of flexion.
The rod bumper 702 further includes a distal housing 708 to capture
the transition cable rod 701 therein. The distal housing 708 is
necessary to ensure the transition cable rod 701 remains aligned
with the rod bumper 702 given the flexibility of the transition
cable rod 701. The distal housing 708 is similar to the previously
described examples of housings in that it has a base 710 and a pair
of upstanding arms 712 that act in concert to form a rod channel
714. A locking element 716 may also be included to ensure the
transition cable rod 701 remains in the rod channel 714. The
locking element 716 may be any of the previously described examples
of locking elements. Although described herein with regard to this
specific example, other configurations are possible. For example
the distal housing 708 may be replaced by a loop that achieves the
goal of keeping the transition cable rod 701 aligned with the rod
engaging surface 706.
[0171] FIGS. 92-95 illustrate an example of another fixation
assembly that works to counteract flexion at the proximal and/or
distal instrumented vertebra. The fixation assembly 720 described
herein forms part of the spinal fixation system 10 and is suitable
for use with the spinal rod 12 and/or a transition rod 721 such as
one of the several examples described above. By way of example, the
fixation assembly 720 is described herein as being used with both
the spinal rod 12 and a transition rod 721. The fixation assembly
720 includes a first bone anchor 722, a pair of elastomeric sheaths
724, and first and second locking rings 726, 728. The present
example is shown and described with a second bone anchor 730
associated with the spinal rod 12 and implanted at an adjacent
vertebral level.
[0172] The first bone anchor 722 may be any bone anchor suitable
for securing a spinal rod in place relative to a bone. By way of
example, the bone anchor 722 includes a threaded shank 732 and a
ring shaped head 734. Other types of anchors including tulip based
pedicle screws like those described in above examples (as well as
bone anchor 730 of this example) are possible. The threaded shank
732 is configured to provide purchase in bone tissue. The ring
shaped head 734 includes a rod hole 736 sized and configured to
allow passage of the transition rod 721 (or spinal rod 12)
therethrough. One elastomer sleeve 724 is positioned on the rod 721
proximally of the head 734, and the other elastomer sleeve 724 is
positioned on the rod 721 distally of the head 734. The first
locking ring 726 is secured to the rod 721 proximally of the
proximal elastomer sleeve 724. The second locking ring 728 is
secured to the rod 721 distally of the distal elastomer sleeve
724.
[0173] The first locking ring 726 shown by way of example comprises
a body 738 having a rod hole 740 extending therethrough and a
locking element aperture 742 that opens to the rod hole 740 and is
configured to receive a locking element 744. The locking element
744 may be any of the setscrew type locking elements described by
way of example above. Other locking ring configurations are
possible that may or may not need secondary locking elements.
[0174] The second locking ring 728 shown by way of example is
capable of joining a pair of rods and comprises a body 746 having a
rod hole 748 extending therethrough, and first and second locking
element apertures 750, 752 that open to the rod hole 748 and are
configured to receive first and second locking elements 754, 756
respectively. The locking elements 754, 756 may be any of the
setscrew type locking elements described by way of example above.
In the instant example the first locking element 754 secures the
second locking element 728 to the transition rod 721 and the second
locking element 756 secures the second locking element 728 to the
spinal rod 12. Although described as a junction point between the
transition rod 721 and the spinal rod 12, the second locking ring
728 may be secured to only one rod and therefore may be identical
to the first locking ring 726. Other locking ring configurations
are possible that may or may not need secondary locking
elements.
[0175] In an initial unbiased position, the various elements are
positioned such that the proximal elastomer sleeve 724 abuts the
head 734 and first locking ring 726, while the distal elastomer
sleeve 724 abuts the head 734 and second locking ring 726. When
flexion occurs and the rod 721 experiences forward bending, the
elastomer sleeves 724 will be compressed and as a result exert a
counterforce back on the first and second locking rings 726, 728
and head 734. This counterforce will work to return the rod 721
toward its initial position.
[0176] FIGS. 96-98 illustrate an example of another fixation
assembly that works to present a physical barrier to flexion at the
proximal and/or distal instrumented vertebra. The fixation assembly
760 described herein forms part of the spinal fixation system 10
and is suitable for use with the spinal rod 12 and/or a transition
rod such as one of the several examples described above. By way of
example, the fixation assembly 760 includes bone anchor 762,
flexible cable rod 764, and attachment element 766. The present
example is shown and described with a second bone anchor 768
associated with the spinal rod 12 and implanted at an adjacent
vertebral level.
[0177] The bone anchor 762 may be any bone anchor suitable for
securing a spinal rod in place relative to a bone. By way of
example, the bone anchor 762 includes a threaded shank 770 and a
ring shaped head 772. Other types of anchors including tulip based
pedicle screws like those described in above examples (as well as
bone anchor 768 of this example) are possible. The threaded shank
770 is configured to provide purchase in bone tissue. The ring
shaped head 772 includes a rod hole 774 sized and configured to
allow passage of the cable rod 764 therethrough. The head 772
further includes a proximal abutment surface 776 oriented toward
the proximal end of the cable rod 764 and configured to flushly
engage the flexion stop 778 when necessary during flexion.
[0178] The cable rod 764 is a flexible cable and has a proximal
terminus comprising a flexion stop 778. By way of example, the
flexion stop 778 is a rigid member attached to the end of the cable
rod 764 and having a diameter (or length dimension) that is greater
than the diameter of the rod hole 774 so that the flexion stop 778
is incapable of passing through the rod hole 774. During flexion
the cable rod 764 will be pulled through the rod hole 774 until the
flexion stop 778 abuts the abutment surface 776. When this abutment
happens, the top vertebra (that is falling forward) will in effect
be held up by the cable rod 764, preventing further flexion from
occurring.
[0179] The attachment element 766 is configured to attach the
distal end of the cable rod 764 to the proximal end of the spinal
rod 12. By way of example, the attachment element 766 comprising a
housing 780 having a rod channel 782 and a plurality of locking
element apertures 784, each of which is configured to receive a
locking element 786. In use, the distal end of the cable rod 764 is
received within the rod channel 782 and secured with the proximal
most locking element 786. The proximal end of the spinal rod 12 is
received within the rod channel 782 and secured with the distal
most locking element 786. In the present example, the locking
elements 786 may be one of the several examples of setscrew type
locking elements described above. Although shown and described
herein as a housing and setscrew based attachment mechanism, it
should be understood that the cable rod 764 and spinal rod 12 may
be joined by any suitable method without departing from the scope
of this disclosure.
[0180] Several of the examples described herein involve tethers
attached to the bone anchor or to a bone hook that then act as
artificial ligaments to secure the rod to the bone. In some
instances it may not be necessary to attach the tethers to
implanted hardware other than the rod. In these instances it is
contemplated that the tether may be wrapped around the bone
structure without having a terminus that is attached to implanted
hardware.
[0181] While specific embodiments have been shown by way of example
in the drawings and described herein in detail, it will be
appreciated that the invention is susceptible to various
modifications and alternative forms (beyond combining features
disclosed herein). The description herein of specific embodiments
is not intended to limit the invention to the particular forms
disclosed, but on the contrary, the invention is to cover all
modifications, equivalents, and alternatives falling within the
spirit and scope of the invention.
* * * * *