U.S. patent number RE45,676 [Application Number 13/973,462] was granted by the patent office on 2015-09-29 for system and method for spinal implant placement.
This patent grant is currently assigned to Stryker Spine. The grantee listed for this patent is Stryker Spine. Invention is credited to Joshua A. Butters, Kingsley Richard Chin, T. Wade Fallin, Daniel F. Justin.
United States Patent |
RE45,676 |
Chin , et al. |
September 29, 2015 |
**Please see images for:
( Certificate of Correction ) ** |
System and method for spinal implant placement
Abstract
A posterior spinal fusion system may include a plurality of
cannulas that mate with cages polyaxially coupled to pedicle
screws. The cannulas maintain access to the pedicle screws to
facilitate percutaneous insertion of a fusion rod into engagement
with the cages. Each cannula has a pair of blades that may be held
together by an abutment member that at least partially encircles
the blades. Each abutment member abuts the skin to define a
variable subcutaneous length of the corresponding cannula. Each
abutment members is also lockably removable from the corresponding
blades to enable the blades to pivot with respect to the connecting
element to a position in which they can be withdrawn from the
connecting element. The blades of each cannula are spaced apart to
provide first and second slots of each cannula, through which the
fusion rod can be percutaneously inserted.
Inventors: |
Chin; Kingsley Richard (Fort
Lauderdale, FL), Fallin; T. Wade (Hyde Park, UT),
Butters; Joshua A. (Chandler, AZ), Justin; Daniel F.
(Orlando, FL) |
Applicant: |
Name |
City |
State |
Country |
Type |
Stryker Spine |
Cestas |
N/A |
FR |
|
|
Assignee: |
Stryker Spine
(FR)
|
Family
ID: |
37432272 |
Appl.
No.: |
13/973,462 |
Filed: |
August 22, 2013 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
Issue Date |
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13972493 |
Aug 21, 2013 |
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10868075 |
Jun 7, 2011 |
7955355 |
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60518580 |
Nov 8, 2003 |
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60682783 |
May 19, 2005 |
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Reissue of: |
11202487 |
Aug 12, 2005 |
8002798 |
Aug 23, 2011 |
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Reissue of: |
11202487 |
Aug 12, 2005 |
8002798 |
Aug 23, 2011 |
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Current U.S.
Class: |
1/1 |
Current CPC
Class: |
A61B
17/3201 (20130101); A61B 17/7037 (20130101); A61B
17/7082 (20130101); A61B 17/7085 (20130101); A61B
17/7083 (20130101); A61B 90/00 (20160201); A61B
17/7035 (20130101); A61B 17/7091 (20130101); A61B
17/3417 (20130101); A61B 17/00234 (20130101); A61B
2090/036 (20160201); A61B 2017/3443 (20130101); A61B
17/3421 (20130101); A61B 2090/037 (20160201); A61B
17/701 (20130101); A61B 2017/3492 (20130101); A61B
2017/00738 (20130101); A61B 2017/3445 (20130101); A61B
90/39 (20160201); A61B 17/7032 (20130101) |
Current International
Class: |
A61B
17/88 (20060101); A61B 17/70 (20060101) |
Field of
Search: |
;606/60,86A,246,279 |
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|
Primary Examiner: Woodall; Nicholas
Attorney, Agent or Firm: Lerner, David, Littenberg, Krumholz
& Mentlik, LLP
Parent Case Text
CROSS-REFERENCE TO RELATED APPLICATIONS
.[.This.]. .Iadd.Notice: More than one reissue application has been
filed for the reissue of U.S. Pat. No. 8,002,798. The reissue
applications are U.S. application Ser. No. 13/972,493 and U.S.
application Ser. No. 13/973,462 (the present application). The
present .Iaddend.application .Iadd.is a continuation reissue of
U.S. application Ser. No. 13/972,493, filed on Aug. 21, 2013, which
is an application for reissue of U.S. Pat. No. 8,002,798, which
.Iaddend.is a continuation-in-part of U.S. application Ser. No.
10/868,075, filed on Jun. 15, 2004, which claims the .[.benefir.].
.Iadd.benefit .Iaddend.of U.S. Provisional Application No.
60/518,580, filed Nov. 8, 2003, the .[.disclosure.].
.Iadd.disclosures .Iaddend.of which are incorporated herein by
reference. .[.This application claim.]. .Iadd.U.S. Pat. No.
8,002,798 claims .Iaddend.the benefit of U.S. Provisional
Application No. 60/682,783, filed on May 19, 2005, the disclosure
of which is incorporated herein by reference.
This application relates to U.S. Application Ser. No. 10/669,927,
filed on Sep. 24, 2003, the disclosure of which is hereby
incorporated herein by reference.
Claims
The invention claimed is:
.[.1. A system for providing access to a spine of a patient, the
system comprising: a first connecting element implantable in a
first vertebra of a spine; and a first cannula adapted to receive
at least a portion of a spinal fusion rod therealong, the first
cannula comprising: a first blade; and a second blade discrete from
the first blade; wherein the first and second blades are configured
to be assembled together substantially parallel to each other and
mated with the first connecting element, without being directly
connected to one another, in order to provide the first cannula
such that the first cannula has a distal end terminating at the
connecting element, whereby the first cannula provides access to
the spine when the first connecting element is implanted in the
first vertebra of the spine; and wherein the first and second
blades are independently detachable from the first connecting
element such that the first and second blades are independently
removable from the patient..].
.[.2. The system of claim 1, wherein the connecting element
comprises a pedicle screw implantable in a pedicle of the first
vertebra, and a cage polyaxially movable with respect to the
pedicle screw..].
.[.3. The system of claim 1, wherein the first and second blades
are configured to be disassembled from one another without removing
the distal end from within the patient..].
.[.4. The system of claim 3, wherein each of the first and second
blades comprises a locked configuration, in which the blade is
secured to the connecting element, and an unlocked configuration,
in which the blade is removable from the connecting element,
wherein each of the first and second blades is movable between the
locked and unlocked configurations in response to rotation of the
blade with respect to the connecting element..].
.[.5. The system of claim 4, wherein each of the first and second
blades is movable between the locked and unlocked configurations in
response to rotation of the blade about an axis substantially
perpendicular to a longitudinal axis of the first cannula..].
.[.6. The system of claim 1, further comprising an abutment member
configured to engage the first and second blades to restrict
relative motion between the first and second blades..].
.[.7. The system of claim 6, wherein the abutment member is
lockable with respect to the first and second blades by a locking
mechanism that restricts withdrawal of the abutment member from the
first and second blades..].
.[.8. The system of claim 7, wherein the locking mechanism
comprises a plurality of proximal tabs of the first and second
blades, wherein the proximal tabs are bendable to permit withdrawal
of the abutment member from the first and second blades..].
.[.9. The system of claim 1, further comprising an abutment member
encircling at least a portion of the first cannula to abut an
exterior skin surface of the patient, wherein the abutment member
is movable along the first cannula to define a variable
subcutaneous length of the first cannula..].
.[.10. The system of claim 9, wherein the abutment member is shaped
such that a combined length of the first cannula and the abutment
member does not change in response to motion of the abutment member
along the first cannula..].
.[.11. The system of claim 1, wherein the first and second blades
are shaped such that, when positioned to define the first cannula,
the first and second blades provide a first slot in a side wall of
the first cannula..].
.[.12. The system of claim 11, wherein the first and second blades
are further shaped such that, when positioned to define the first
cannula, the first and second blades provide a second slot in the
side wall, wherein the second slot is arranged with respect to the
first slot to permit passage of a rod through the first cannula
along a direction transverse to a longitudinal axis of the first
cannula..].
.[.13. The system of claim 12, wherein the distal end is insertable
into the patient proximate the spine such that each of the first
and second slots extends unbroken along an entire subcutaneous
length of the cannula..].
.[.14. The system of claim 1, further comprising a second cannula
securable to a second connecting element implantable in a second
vertebra of the spine, and a third cannula securable to a third
connecting element implantable in a third vertebra of the spine,
wherein the first, second, and third cannulas cooperate to
facilitate attachment of a rod to the first, second, and third
connecting elements to restrict relative motion of the first,
second, and third vertebrae..].
.[.15. The system of claim 1, wherein the first and second blades
have arcuate profiles, whereby the first cannula is defined by a
partially cylindrical shape..].
.[.16. The system of claim 1, wherein the first and second blades
each have a distal end including a tab insertable into a
corresponding slot of the first connecting element..].
.[.17. The system of claim 1, further comprising an abutment member
configured to prevent the first and second blades from becoming
disconnected from the first connecting element..].
.[.18. A system for providing access to a spine of a patient, the
system comprising: a cannula adapted to receive at least a portion
of a spinal fusion rod therealong, the cannula comprising a
proximal end and a distal end insertable into the patient proximate
the spine, the distal end comprising a docking element discrete
from and securable to a connecting element implantable in a first
vertebra of the spine; wherein the docking element is receivable by
the connecting element in both a docked configuration and an
undocked configuration, the distal end being secured to the
connecting element in the docked configuration, and the distal end
being received by and removable from the connecting element in the
undocked configuration, and wherein the docking element is movable
between the docked and undocked configurations in response to
rotation about an axis substantially perpendicular to a
longitudinal axis of the cannula..].
.[.19. The system of claim 18, wherein the connecting element
comprises a pedicle screw implantable in a pedicle of the first
vertebra, and a cage polyaxially movable with respect to the
pedicle screw, wherein the docking element is configured to dock
with the cage..].
.[.20. The system of claim 19, wherein the cannula comprises: a
first blade; and a second blade discrete from the first blade;
wherein the first and second blades are positionable substantially
parallel to each other to provide the first cannula; wherein each
of the first and second blades comprises a locked configuration, in
which the blade is secured to the connecting element, and an
unlocked configuration, in which the blade is removable from the
connecting element..].
.[.21. The system of claim 18, wherein the docking element includes
a plurality of tabs, each of the first and second blades comprising
at least one of the tabs at a distal end thereof, the tabs enabling
rotation of the blades between the locked configuration and the
unlocked configuration..].
.[.22. The system of claim 18, further comprising an abutment
member configured to engage the first and second blades to restrict
relative motion between the first and second blades to restrict
motion of the blades to the unlocked configuration..].
.[.23. The system of claim 22, wherein the abutment member is
lockable with respect to the first and second blades by a locking
mechanism that restricts withdrawal of the abutment member from the
first and second blades..].
.[.24. The system of claim 23, wherein the locking mechanism
comprises a proximal tab of each of the first and second blades,
wherein the proximal tabs are bendable to permit withdrawal of the
abutment member from the first and second blades..].
.[.25. A system for providing access to a spine of a patient, the
system comprising: a cannula adapted to receive at least a portion
of a spinal fusion rod therealong, the cannula comprising a distal
end insertable into the patient proximate the spine and securable
to a connecting element implantable in a first vertebra of the
spine, the cannula further comprising a proximal end and a
longitudinal axis extending between the proximal and distal ends;
and an abutment member encircling at least a portion of the cannula
and adapted to abut an outward facing surface of skin of the
patient, the entire length of the abutment member along the
longitudinal axis of the cannula being disposed between the
proximal and distal ends of the cannula, wherein the abutment
member is adapted to move along the cannula from the proximal end
to the distal end such that the abutment member can be moved to a
position abutting the outward facing surface of skin when the
distal end of the cannula is secured to the connecting element,
whereby a variable subcutaneous length of the cannula is defined,
and wherein a combined length of the cannula and the abutment
member does not change in response to motion of the abutment member
along the cannula..].
.[.26. The system of claim 25, wherein the cannula comprises: a
first blade; and a second blade discrete from the first blade;
wherein the first and second blades are positionable substantially
parallel to each other to provide the cannula..].
.[.27. The system of claim 26, wherein the abutment member is
configured to engage the first and second blades to restrict
relative motion between the first and second blades..].
.[.28. The system of claim 25, wherein the abutment member is
lockable with respect to the cannula by a locking mechanism that
restricts withdrawal of the abutment member from the
cannula..].
.[.29. The system of claim 28, wherein the locking mechanism
comprises a plurality of proximal tabs of the cannula, wherein the
proximal tabs are bendable to permit withdrawal of the abutment
member from the cannula..].
.[.30. The system of claim 25, wherein the cannula comprises a
first slot extending longitudinally along a side wall of the
cannula..].
.[.31. The system of claim 25, wherein the cannula comprises a
docking element that couples the cannula to a connecting element
implantable in a vertebra of the spine, wherein the docking element
comprises a frangible coupling configured to fracture in response
to application of a threshold force against the frangible coupling
to permit removal of the distal end from the connecting
element..].
.[.32. A system for providing access to a spine of a patient, the
system comprising: a cannula comprising: a first component; and a
second component discrete from the first component; and an abutment
member; wherein the first and second components are configured to
be assembled to a connecting element implantable in a first
vertebra of the spine, wherein each of the first and second
components has a distal end receivable in the connecting element in
a receiving position and a locked position, each of the first and
second components being movable between the receiving position and
the locked position in response to rotation about an axis
substantially perpendicular to a longitudinal axis of the cannula,
wherein the abutment member configured to engage the first and
second components to restrict relative motion between the first and
second components, and wherein the abutment member is lockable with
respect to the first and second components by a locking mechanism
that restricts withdrawal of the abutment member from the first and
second blades..].
.[.33. The system of claim 32, wherein the first component
comprises a first blade, and the second component comprises a
second blade, wherein the first and second blades are positionable
substantially parallel to each other to provide the cannula..].
.[.34. The system of claim 33, wherein the distal end comprises a
docking element securable to a connecting element implantable in a
first vertebra of the spine, wherein each of the first and second
blades is secured to the connecting element in the locked position
and received within but removable from the connecting element in
the receiving position..].
.[.35. The system of claim 32, wherein the locking mechanism
comprises a plurality of proximal tabs of the first and second
components, wherein the proximal tabs are bendable to permit
withdrawal of the abutment member from the first and second
components..].
.[.36. The system of claim 32, wherein the first and second
components have arcuate surfaces, whereby the cannula is defined by
a partially cylindrical shape..].
.[.37. A system for providing access to a spine of a patient, the
system comprising: a cannula adapted to receive at least a portion
of a spinal fusion rod therealong, the cannula having a
longitudinal axis and comprising a distal end insertable into the
patient proximate the spine, and a proximal end, the distal end
comprising a docking element securable to a connecting element
implantable in a first vertebra of the spine; and an abutment
member encircling at least a portion of the cannula, the abutment
member having an abutment surface substantially normal to the
longitudinal axis, the abutment surface adapted to abut an exterior
skin surface of the patient, wherein the abutment member is adapted
to move along the cannula from the proximal end to the distal end
such that the abutment member can be moved to a position wherein
the abutment surface abuts the exterior skin surface when the
docking element is secured to the connecting element implanted in
the first vertebra of the spine, whereby a variable subcutaneous
length of the cannula is defined..].
.[.38. The system of claim 37, wherein the connecting element
comprises a pedicle screw implantable in a pedicle of the first
vertebra, and a cage polyaxially movable with respect to the
pedicle screw..].
.[.39. The system of claim 37, wherein the abutment member is
lockable with respect to the cannula by a locking mechanism that
restricts withdrawal of the abutment member from the
cannula..].
.[.40. The system of claim 39, wherein the locking mechanism
comprises a plurality of proximal tabs of the cannula, wherein the
proximal tabs are bendable to permit withdrawal of the abutment
member from the cannula..].
.[.41. The system of claim 37, wherein the abutment member is
shaped such that a combined length of the cannula and the abutment
member does not change in response to motion of the abutment member
along the cannula..].
.[.42. The system of claim 37, wherein the cannula further
comprises a first slot portion formed in a side wall of the
cannula..].
.[.43. The system of claim 42, wherein the cannula further
comprises a second slot portion formed in the side wall, wherein
the second slot is arranged with respect to the first slot to
permit passage of a rod through the cannula along a direction
transverse to the longitudinal axis of the cannula..].
.[.44. The system of claim 43, wherein the distal end is insertable
into the patient proximate the spine such that each of the first
and second slots extends unbroken along the entire subcutaneous
length..].
.[.45. The system of claim 37, wherein the docking element
comprises a frangible coupling configured to fracture in response
to application of a threshold force against the frangible coupling
to permit removal of the distal end from the connecting
element..].
.[.46. The system of claim 37, wherein the cannula comprises: a
first blade; and a second blade discrete from the first blade;
wherein the first and second blades are positionable substantially
parallel to each other to provide the cannula, and wherein the
abutment member is configured to engage the first and second blades
to restrict relative motion between the first and second
blades..].
.[.47. A system for providing access to a spine of a patient, the
system comprising: a cannula adapted to receive at least a portion
of a spinal fusion rod therealong, the cannula comprising a distal
end insertable into the patient proximate the spine and securable
to a connecting element implantable in a first vertebra of the
spine, the cannula further comprising a proximal end and a first
slot extending longitudinally between the distal and proximal ends;
and an abutment member encircling at least a portion of the
cannula, the abutment member having an abutment surface extending
substantially laterally from an outer surface of the cannula, the
abutment surface adapted to abut an exterior skin surface of the
patient, wherein the abutment member is adapted to move along the
cannula from the proximal end to the distal end such that the
abutment member can be moved to a position wherein the abutment
surface abuts the exterior skin surface when the distal end of the
cannula is secured to the connecting element implanted in the first
vertebra of the spine, whereby a variable subcutaneous length of
the cannula is defined..].
.[.48. The system of claim 47, wherein the abutment member is
lockable with respect to the cannula by a locking mechanism that
restricts withdrawal of the abutment member from the
cannula..].
.[.49. The system of claim 48, wherein the locking mechanism
comprises a plurality of proximal tabs of the cannula, wherein the
proximal tabs are bendable to permit withdrawal of the abutment
member from the cannula..].
.[.50. The system of claim 47, wherein the abutment member is
shaped such that a combined length of the cannula and the abutment
member does not change in response to motion of the abutment member
along the cannula..].
.[.51. The system of claim 47, wherein the cannula further
comprises a second slot portion formed in the side wall, wherein
the second slot is arranged with respect to the first slot to
permit passage of a rod through the cannula along a direction
transverse to a longitudinal axis of the cannula..].
.[.52. The system of claim 51, wherein the distal end is insertable
into the patient proximate the spine such that each of the first
and second slots extends unbroken along the entire subcutaneous
length..].
.[.53. The system of claim 47, wherein the cannula comprises a
docking element that couples the cannula to a connecting element
implantable in a vertebra of the spine, wherein the docking element
comprises a frangible coupling configured to fracture in response
to application of a threshold force against the frangible coupling
to permit removal of the distal end from the connecting
element..].
.[.54. The system of claim 47, wherein the cannula comprises: a
first blade; and a second blade discrete from the first blade;
wherein the first and second blades are positionable substantially
parallel to each other to provide the cannula, and wherein the
abutment member is configured to engage the first and second blades
to restrict relative motion between the first and second
blades..].
.Iadd.55. A method for providing access to a spine of a patient,
the method comprising: implanting a first connecting element
through a first incision in the skin of the patient and into a
first vertebra of the spine with a first blade and a second blade
coupled to the first connecting element so that each of the first
and second blades extend proximally therefrom through the first
incision, the first and second blades being positioned adjacent to
one another to provide a first longitudinal pathway therealong
between the first and second blades; moving an implant into
engagement with the first connecting element through at least a
portion of the first longitudinal pathway; and independently
uncoupling the first and second blades from the first connecting
element and independently removing the first and second blades from
the body of the patient while the first connecting element remains
implanted in the first vertebra..Iaddend.
.Iadd.56. The method of claim 55, wherein the connecting element
comprises a pedicle screw having a cage connected thereto for
receiving the implant, the step of implanting the first connecting
element in the first vertebra comprising implanting the pedicle
screw in a pedicle of the first vertebra..Iaddend.
.Iadd.57. The method of claim 55, wherein the implant is a spinal
fusion rod..Iaddend.
.Iadd.58. The method of claim 55, wherein the first and second
blades define opposing first and second slots therebetween, and
wherein the step of moving the implant into engagement with the
first connecting element comprises subcutaneously passing the
implant through the first and second slots along a direction
transverse to the first longitudinal pathway..Iaddend.
.Iadd.59. The method of claim 55, further comprising: inserting a
cutting tool along the first longitudinal pathway; and using the
cutting tool to cut subcutaneous tissue proximate to the first
longitudinal pathway..Iaddend.
.Iadd.60. The method of claim 55, further comprising attaching the
first and second blades to the first connecting element prior to
the step of implanting the first connecting element in the first
vertebra..Iaddend.
.Iadd.61. The method of claim 60, wherein the step of attaching the
first and second blades to the first connecting element comprises
inserting a first tab at a distal end of the first blade into a
first slot of the first connecting element and inserting a second
tab at a distal end of the second blade into a second slot of the
first connecting element..Iaddend.
.Iadd.62. The method of claim 55, wherein the first and second
blades are each connected to the first connecting element by a
respective frangible portion, and wherein the step of uncoupling
the first and second blades from the first connecting element
comprises fracturing the frangible portion associated with each of
the first and second blades..Iaddend.
.Iadd.63. The method of claim 62, wherein fracturing the frangible
portion associated with each of the first and second blades
comprises tilting each of the first and second blades with respect
to the connecting element..Iaddend.
.Iadd.64. The method of claim 55, wherein each of the first and
second blades comprises a locked configuration, in which the
respective first and second blade is secured to the first
connecting element, and an unlocked configuration, in which the
respective first and second blade is received by and removable from
the first connecting element..Iaddend.
.Iadd.65. The method of claim 64, further comprising rotating the
first and second blades to move the first and second blades between
the respective locked and unlocked configurations..Iaddend.
.Iadd.66. The method of claim 65, wherein rotating the first and
second blades comprises pushing the first and second blades inward
towards a central longitudinal axis defined along the longitudinal
pathway..Iaddend.
.Iadd.67. The method of claim 55, further comprising engaging the
first and second blades with an abutment member..Iaddend.
.Iadd.68. The method of claim 67, wherein engaging the first and
second blades with an abutment member comprises maintaining the
first and second blades in a substantially parallel relationship
with the abutment member..Iaddend.
.Iadd.69. The method of claim 67, further comprising moving the
abutment member along the first and second blades..Iaddend.
.Iadd.70. The method of claim 69, further comprising moving the
abutment member to a position abutting an outward facing surface of
the skin of the patient..Iaddend.
.Iadd.71. The method of claim 67, further comprising restricting
withdrawal of the abutment member from the first and second
blades..Iaddend.
.Iadd.72. The method of claim 55, further comprising implanting a
second connecting element through a second incision in the skin of
the patient and into a second vertebra of the spine with a third
blade and a fourth blade coupled to the second connecting element
so that each of the third and fourth blades extend proximally
therefrom through the second incision, the third and fourth blades
being positioned adjacent to one another to provide a second
longitudinal pathway therealong between the third and fourth
blades..Iaddend.
.Iadd.73. The method of claim 72, further comprising implanting a
third connecting element through a third incision in the skin of
the patient and into a third vertebra of the spine with a fifth
blade and a sixth blade coupled to the third connecting element so
that each of the fifth and sixth blades extend proximally therefrom
through the third incision, the fifth and sixth blades being
positioned adjacent to one another to provide a third longitudinal
pathway therealong between the fifth and sixth blades..Iaddend.
.Iadd.74. A method for providing access to a spine of a patient,
the method comprising: implanting a first connecting element
through a first incision in the skin of the patient and into a
first vertebra of the spine with a first blade and a second blade
coupled to the first connecting element so that each of the first
and second blades extend proximally through the first incision when
the first connecting element is implanted in the first vertebra,
and wherein the first and second blades are positioned adjacent to
one another to provide a first longitudinal pathway therealong
between the first and second blades; implanting a second connecting
element through a second incision in the skin of the patient and
into a second vertebra of the spine with a third blade and a fourth
blade coupled to the second connecting element so that each of the
third and fourth blades extend proximally through the second
incision when the second connecting element is implanted in the
second vertebra, and wherein the third and fourth blades are
positioned adjacent to one another to provide a second longitudinal
pathway therealong between the third and fourth blades; moving an
implant into engagement with the first and second connecting
elements through at least a portion of the first longitudinal
pathway; independently uncoupling the first and second blades from
the first connecting element and removing the first and second
blades from the body of the patient while the first connecting
element remains implanted in the first vertebra; and independently
uncoupling the third and fourth blades from the second connecting
element and removing the third and fourth blades from the body of
the patient while the second connecting element remains implanted
in the second vertebra..Iaddend.
.Iadd.75. The method of claim 55, further comprising maintaining
opposing sides of the first incision apart around the first
longitudinal pathway with the first and second blades..Iaddend.
.Iadd.76. The method of claim 74, further comprising: maintaining
opposing sides of the first incision apart around the first
longitudinal pathway with the first and second blades; and
maintaining opposing sides of the second incision apart around the
second longitudinal pathway with the third and fourth
blades..Iaddend.
.Iadd.77. The method of claim 74, wherein the first, second, third,
and fourth blades are each connected to the respective connecting
elements by a respective frangible portion, wherein the step of
uncoupling the first and second blades from the first connecting
element comprises fracturing the frangible portion associated with
each of the first and second blades, and wherein the step of
uncoupling the third and fourth blades from the second connecting
element comprises fracturing the frangible portion associated with
each of the third and fourth blades..Iaddend.
Description
BACKGROUND OF THE INVENTION
1. The Field of the Invention
The present invention relates generally to implantable devices, and
more precisely, to posterior spinal fusion systems.
2. The Relevant Technology
Many people experience joint pain in one form or another. In
particular, back pain may result from the occurrence of a wide
variety of spinal pathologies. Some such pathologies are currently
treated by fusing adjacent vertebrae to prevent their relative
motion. According to one known method, pedicle screws are implanted
in the pedicles and are rigidly secured to a rod passing posterior
to the pedicles.
Unfortunately, current procedures often involve the exposure of a
relatively large area to permit implantation of the rod. Some
current procedures cannot be used to implant a rod that secures
more than two vertebrae together. Other known procedures are
somewhat complex, and therefore require many parts and surgical
steps. Accordingly, there is a need for new fusion rod implantation
systems and methods that remedy the shortcomings of the prior
art.
BRIEF DESCRIPTION OF THE DRAWINGS
Various embodiments of the present invention will now be discussed
with reference to the appended drawings. It is appreciated that
these drawings depict only typical embodiments of the invention and
are therefore not to be considered limiting of its scope.
FIG. 1 is a perspective view of two adjacent vertebrae of a spine,
with guide wires implanted in the pedicles of the right side.
FIG. 2 is a perspective view of three guide wires in isolation,
positioned as though implanted in the pedicles of the right sides
of three adjacent vertebrae.
FIG. 3 is a perspective view of the guide wires of FIG. 2, with
dilators advanced along the guide wires to dilate surrounding
tissue.
FIG. 4 is a perspective view of the guide wires and dilators of
FIG. 3, with hollow dilators placed around the solid dilators.
FIG. 5 is a perspective view of the guide wires and hollow dilators
of FIG. 4, with the solid dilators removed.
FIG. 6 is a perspective view of the guide wires and hollow
dilators, with a tapping tool placed over one of the guide wires to
tap the corresponding pedicle.
FIG. 7 is an exploded, perspective view of a cannula, abutment
member, pedicle screw, cage, set screw, and a portion of a rod
according to one embodiment of the invention.
FIG. 8 is a perspective view of the cannula, abutment member,
pedicle screw, cage, set screw, and rod portion of FIG. 7, in
assembled form.
FIG. 9 is a perspective view of a screw insertion tool according to
one embodiment of the invention.
FIG. 10 is a perspective view of the screw insertion tool of FIG.
9, in engagement with the assembly of FIG. 8, excluding the rod
portion and the set screw.
FIG. 11 is a perspective view of the screw insertion tool in use to
implant the assembly of FIG. 8, excluding rod portions and set
screws, over the first guide wire of FIG. 2.
FIG. 12 is a perspective view of a fascia clipping tool according
to one embodiment of the invention.
FIG. 13 is a perspective view of the fascia clipping tool of FIG.
12 inserted into one of the cannulas of FIG. 11 to sever the
adjoining fascia.
FIG. 14 is a perspective view of a rod insertion tool according to
one embodiment of the invention.
FIG. 15 is a perspective view of the rod insertion tool of FIG. 14
secured to a rod to facilitate manual insertion of the rod through
the cannulas of FIG. 11.
FIG. 16 is a perspective view of a rod seating tool according to
one embodiment of the invention.
FIG. 17 is a perspective view of the rod seating tool of FIG. 16
inserted into one of the cannulas of FIG. 11 to help seat the rod
in the cages.
FIG. 18 is a perspective view of a rod holding tool according to
one embodiment of the invention.
FIG. 19 is a perspective view of the rod holding tool of FIG. 18
inserted into one of the cannulas of FIG. 11 to further manipulate
the rod.
FIG. 20 is a perspective view of a set screw driver according to
one embodiment of the invention.
FIG. 21 is a perspective view of the set screw driver of FIG. 20
inserted into one of the cannulas of FIG. 11 to tighten a set screw
to retain the rod within the corresponding cage.
FIG. 22 is a perspective view of the pedicle screws, cages, set
screws, and cannulas of FIG. 11, with the abutment members removed
to permit removal of the cannulas from the cages.
FIG. 23 is a perspective view of three adjacent vertebrae of the
spine, with the rod secured to the pedicle screws to provide
posterior spinal fusion.
FIG. 24 is a perspective view of a cannula and cage according to
one alternative embodiment of the invention, in which the cannula
is secured to the cage by two frangible couplings.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
The present invention relates to systems and methods for
implantation of orthopedic devices. Although the examples provided
herein generally relate to insertion of a rod for a posterior
spinal fusion system, the present invention may be applied to any
procedure in which a device is to be implanted in the body in a
minimally invasive manner. Accordingly, the scope of the present
invention is not intended to be limited by the examples discussed
herein, but only by the appended claims.
As used herein, a "cannula" is an elongated structure having a
hollow interior that provides communication between opposite ends
of the elongated structure. A "subcutaneous length" is the portion
of an object that lies below the surface of a patient's skin.
"Transverse" refers to an object or direction that is not parallel
with, and not nearly parallel with, another object or direction. A
"connecting element" is any man-made structure that is implantable
to remain in the body, and is connectable to an anatomic feature
and/or another implantable structure. The term "percutaneous"
refers to an action carried out at least partially underneath
unbroken skin.
The term "discrete" refers to parts that are not formed as a single
piece, but are separate pieces from each other. The term "coupled"
refers to two elements that are secured together, whether they have
been formed separately and secured together via a secondary
operation, or they have been formed as a single piece (i.e., formed
in a coupled state). The term "securable" refers to elements that
are capable of being coupled together, or are already coupled
together. A "blade" is an elongated, thin structure. "Polyaxial
motion" refers to motion along or about multiple orthogonal
axes.
Referring to FIG. 1, a perspective view illustrates a portion of a
spine 10. FIG. 1 illustrates only the bony structures; accordingly,
ligaments, cartilage, and other soft tissues are omitted for
clarity. The spine 10 has a cephalad direction 12, a caudal
direction 14, an anterior direction 16, a posterior direction 18,
and a medial/lateral axis 20, all of which are oriented as shown by
the arrows bearing the same reference numerals. In this
application, "left" and "right" are used with reference to a
posterior view, i.e., a view from behind the spine 10. "Medial"
refers to a position or orientation toward a sagittal plane (i.e.,
plane of symmetry that separates left and right sides from each
other) of the spine 10, and "lateral" refers to a position or
orientation relatively further from the sagittal plane.
As shown, the portion of the spine 10 illustrated in FIG. 1
includes a first vertebra 24, which may be the L5 (Fifth Lumbar)
vertebra of a patient, and a second vertebra 26, which may be the
L4 (Fourth Lumbar) vertebra of the patient. The systems and methods
may be applicable to any vertebra or vertebrae of the spine 10
and/or the sacrum (not shown). In this application, the term
"vertebra" may be broadly interpreted to include the sacrum.
As shown, the first vertebra 24 has a body 28 with a generally
disc-like shape and two pedicles 30 that extend posteriorly from
the body 28. A posterior arch, or lamina 32, extends between the
posterior ends of the pedicles 30 to couple the pedicles 30
together. The first vertebra 24 also has a pair of transverse
processes 34 that extend laterally from the pedicles 30 generally
along the medial/lateral axis 20, and a spinous process 36 that
extends from the lamina 32 along the posterior direction 18.
The first vertebra 24 also has a pair of superior facets 38, which
are positioned toward the top of the first vertebra 24 and face
generally medially. Additionally, the first vertebra 24 has
inferior facets 40, which are positioned toward the bottom of the
first vertebra 24 and face generally laterally. Each of the
pedicles 30 of the first vertebra 24 has a saddle point 42, which
is positioned generally at the center of the juncture of each
superior facet 38 with the adjacent transverse process 34.
Similarly, the second vertebra 26 has a body 48 from which two
pedicles 50 extend posteriorly. A posterior arch, or lamina 52,
extends between the posterior ends of the pedicles 50 to couple the
pedicles 50 together. The second vertebra 26 also has a pair of
transverse processes 54, each of which extends from the
corresponding pedicle 50 generally along the medial/lateral axis
20, and a spinous process 56 that extends from the lamina 52 along
the posterior direction 18.
The second vertebra 26 also has a pair of superior facets 58, which
are positioned toward the top of the second vertebra 26 and face
generally inward. Additionally, the second vertebra 26 has inferior
facets 60, which are positioned toward the bottom of the second
vertebra 26 and face generally outward. Each of the pedicles 60 of
the second vertebra 26 has a saddle point 62, which is positioned
generally at the center of the juncture of each superior facet 58
with the adjacent transverse process 54.
The superior facets 38 of the first vertebra 24 articulate (i.e.,
slide and/or press) with the inferior facets 60 of the second
vertebra 26 to limit relative motion between the first and second
vertebrae 24, 26. Thus, the combination of each superior facet 38
with the adjacent inferior facet 60 provides a facet joint 64. The
first and second vertebrae 24, 26 thus define two facet joints 64
that span the distance between the first and second vertebrae 24,
26. The inferior facets 40 of the first vertebra 40 and the
superior facets 58 of the second vertebra 26 are part of other
facet joints that control motion between the first and second
vertebrae 24, 26 and adjacent vertebrae (not shown) and/or the
sacrum (also not shown).
The vertebrae 24, 26 and/or the intervertebral disc (not shown)
between them, may be damaged or diseased in some manner that makes
it desirable to secure the vertebrae 24, 26 together in a manner
that prevents relative motion between them. Accordingly, posterior
spinal fusion may be employed to secure the pedicles 30, 50
together. FIGS. 1 through 23 illustrate one system and method for
installing a posterior spinal fusion system. FIG. 24 illustrates a
cannula and cage according to one alternative embodiment of the
invention.
As further illustrated in FIG. 1, a first guide wire 70 has been
inserted into the right-side pedicle 30 of the first vertebra 24,
and a second guide wire 72 has been inserted into the right-side
pedicle 50 of the second vertebra 26. The guide wires 70, 72 pass
through the saddle points 42, 62, respectively, of the pedicles 30,
50. Each of the guide wires 70, 72 has a proximal end 74 and a
distal end 76. As shown, the proximal ends 74 are exposed, and the
distal ends 76 are implanted in the pedicles 30, 50. The distal
ends 76 may be implanted by methods known in the surgical arts.
Referring to FIG. 2, a perspective view illustrates the first and
second guide wires 70, 72 of FIG. 1, with the vertebrae 24, 26
removed for clarity. A third guide wire 78 is also shown. The third
guide wire 78 is positioned adjacent to the first and second guide
wires 70, 72 as though the third guide wire 78 were implanted in
the right-hand pedicle of a vertebra (not shown) directly superior
to the second vertebra 26. Accordingly, the method of FIGS. 1
through 23 may be used to secure together vertebrae on multiple
levels, not just two adjacent vertebrae.
Referring to FIG. 3, a perspective view illustrates the guide wires
70, 72, 78, in conjunction with a first dilator 80, a second
dilator 82, and a third dilator 88. Each of the dilators 180, 82,
88 has a proximal end 92 and a distal end 94. The proximal ends 92
may be shaped for gripping by hand, or for attachment to a handle
or the like. The distal ends 94 are rounded to permit relatively
gentle spreading of tissues surrounding the guide wires 70, 72, 78
by the dilators 80, 82, 88.
Each of the dilators 80, 82, 88 has a bore sized to receive the
proximal end 74 of the corresponding guide wire 70, 72, or 78, so
that the dilators 80, 82, 88 are able to slide along the guide
wires 70, 72, 78 toward the distal ends 74, thereby spreading the
tissues away from the guide wires 70, 72, 78. Each of the dilators
80, 82, 88 may optionally include a plurality of nesting elements
that permit discretely gradual dilation. As an alternative to the
guide wires 70, 72, 78 and the dilators 80, 82, 88, a variety of
other guiding devices and/or dilation devices may be used within
the scope of the present invention.
Referring to FIG. 4, a perspective view illustrates the guide wires
70, 72, 78 and dilators 80, 82, 88 of FIG. 3, with first, second,
and third hollow dilators 100, 102, 104 placed around the dilators
80, 82, 88, respectively. Each of the hollow dilators 100, 102, 104
has a generally tubular shape with a proximal end 106, a distal end
108, and a bore 110 extending from the proximal end 106 to the
distal end 108. Each of the bores 110 is sized to receive the
outward-facing surface of the corresponding dilator 80, 82, 88.
Accordingly, the hollow dilators 100, 102, 104 may simply slide
along the anterior direction 16 between the outward-facing surfaces
of the dilators 80, 82, 88 and the adjoining tissues. The hollow
dilators 100, 102, 104 then reach the positions shown in FIG. 4,
thereby removing the dilators 80, 82, 88 from significant contact
with the tissues to be dilated.
Referring to FIG. 5, a perspective view illustrates the guide wires
70, 72, 78 and hollow dilators 100, 102, 104 of FIG. 4, with the
dilators 80, 82, 88 removed. The dilators 80, 82, 88 are simply
withdrawn along the posterior direction 18 from within the hollow
dilators 100, 102, 104 to leave the bores 110 of the hollow
dilators 100, 102, 104 unobstructed.
Referring to FIG. 6, a perspective view illustrates the guide wires
70, 72, 78 and hollow dilators 100, 102, 104, with a tapping tool
120 placed over the first guide wire 70 to tap the corresponding
pedicle (not shown in FIG. 6). As shown, the tapping tool 120 may
have a handle 122 shaped to be gripped by hand, and a shank 124
extending from the handle 122. The shank 124 has a proximal end 126
coupled to the handle 122 and a distal end 128 having a plurality
of threads 130.
The tapping tool 120 also has a bore (not shown) extending through
the shank 124 and through at least a portion of the handle 122. The
bore is sized to receive any of the guide wires 70, 72, 78 so that
the tapping tool 120 can be guided sequentially along each of the
guide wires 70, 72, 78 to tap the pedicle 30 of the first vertebra
24, the pedicle 50 of the second vertebra 26, and the pedicle of
the third vertebra (not shown in FIG. 6). Tapping is carried out by
rotating the handle 122 clockwise while exerting axial pressure on
the handle 122 to cause the distal end 128 to penetrate the bone.
After a pedicle has been tapped, the distal end 128 is withdrawn
from the tapped cavity by rotating the handle 122
counterclockwise.
Referring to FIG. 7, an exploded, perspective view illustrates a
connecting element 140, a cannula 142, an abutment member 144, and
a rod portion 146 according to one embodiment of the invention. The
rod portion 146 is a segment of a longer rod that may be used to
secure the first vertebra 24, the second vertebra 26, and the third
vertebra (not shown in FIG. 7) together. The connecting element 140
is used to secure the rod portion 146 to one pedicle of the
vertebrae to be secured together. The cannula 142 is used to
maintain access to the connecting element 140 after it has been
implanted in the pedicle in a manner that facilitates percutaneous
placement of the rod portion 146 and attachment of the rod portion
146 to the connecting element 140. The abutment member 144 helps to
hold the cannula 142 together and keep it secured to the connecting
element 140 in a manner that will be described subsequently.
As embodied in FIG. 7, the connecting element 140 has a pedicle
screw 150, a cage 152, and a set screw 154. The pedicle screw 150
is the portion of the connecting element 140 that is implanted in
the corresponding pedicle. The pedicle screw 150 is able to hold
the cage 152 against the pedicle at any of a variety of
orientations of the cage 152 with respect to the pedicle screw 150.
Thus, the cage 152 is polyaxially movable with respect to the
pedicle screw 150 until the set screw 154 is tightened into the
cage 152 to lock the orientation of the cage 152 with respect to
the pedicle screw 150.
The pedicle screw 150 has a head 160 and a shank 162. The head 160
has a convex semispherical underside that engages the cage 152 in
any of a variety of relative orientations to provide the polyaxial
coupling described previously. The head 160 also has a hexagonal
recess 164 designed to receive a hexagonal end of a pedicle screw
driver (not shown in FIG. 7), which will be shown and described
subsequently. The shank 162 has a plurality of threads 166 that
rotate into threaded engagement with the tapped pedicle. The
pedicle screw 150 also has a bore (not shown) extending through the
shank 162 and the head 160 to receive any of the guide wires 70,
72, 78 to facilitate guiding of the pedicle screw 150 into
engagement with the corresponding pedicle.
The cage 152 has a base 168 in which an aperture 170 is formed. The
aperture 170 is sized such that the shank 162 of the pedicle screw
150 may be inserted through the aperture 170. The head 160 of the
pedicle screw 150 then rests on a concave semispherical surface of
the base 168, within which the head 160 is polyaxially rotatable.
The cage 152 also has a pair of arms 172 that extend from the base
168, generally parallel to each other. Each of the arms 172 has a
slot 174 and an exterior recess 176. The slots 174 pass through the
arms 172 to communicate with the slots 174. Each of the arms 172
has an inward-facing surface on which a plurality of threads 178
are formed to receive the set screw 154. The arms 172 define
recesses therebetween, and the recesses form ends of a trough in
which the rod portion 146 is able to rest.
As shown, the set screw 154 has a hexagonal recess 180 that enables
the set screw 154 to be rotated by a driver that will be shown and
described subsequently. The set screw 154 also has an
outward-facing surface on which a plurality of threads 182 are
formed to enable the set screw 154 to rotate into threaded
engagement with the cage 152. Once the rod portion 146 is
positioned between the arms 172 of the cage 152, the set screw 154
may be tightened to press the rod portion 146 against the head 160
of the pedicle screw 150, thereby resisting further relative
rotation between the cage 152 and the pedicle screw 150.
Upon assembly, the cannula 142, which is shown in exploded form in
FIG. 7, will have a proximal end 190 and a distal end 192. The
cannula 142 may be dimensioned such that the proximal end 190
protrudes above the skin, while the distal end 192 is securable to
the cage 152 and is insertable through the skin along with the cage
152. The cannula 142 includes a first blade 194 and a second blade
196, which may be substantially identical to each other. Each of
the blades 194, 196 has a proximal end 198 corresponding to the
proximal end 190 of the cannula 142, and a distal end 200
corresponding to the distal end 192 of the cannula 142.
Each proximal end 198 has a proximal tab 202, and each distal end
200 has a distal tab 204. Each proximal tab 202 has a locking ridge
206 that protrudes generally outward, and extends generally
circumferentially. Each proximal tab 202 is also elongated, with a
thin cross section that permits bending toward and away from the
axis (not shown) of the cannula. Each distal tab 204 has bends 208
that cause the distal tab 204 to jut outward, while remaining
generally parallel with the remainder of the corresponding blade
194 or 196.
Each of the distal tabs 204 is insertable through the slot 174 of
the adjacent arm 172 of the cage 152 when the corresponding blade
194 or 196 is tilted to position the proximal end 198 inward
relative to the distal end 200. Once the distal tabs 204 have
passed through the slots 174, rotation of the blades 194 or 196
back to a position generally parallel to each other, and to the
axis of the cage 152, causes the distal tabs 204 to lie within the
exterior recesses 176 of the arms 172 such that the bends 208 are
unable to slide back through the slots 174. Thus, the blades 194,
196 are then in a locked configuration, and cannot be detached from
the cage 152 until they are again moved to the unlocked
configuration, i.e., tilted to position the proximal ends 198
inward.
As long as the blades 194, 196 remain generally parallel to each
other, the distal end 192 of the cannula 142 remains secured to the
cage 152. Thus, the distal tabs 204 form a docking element that
removably secures the cannula 142 to the connecting element 140.
The abutment member 144 serves to keep the blades 194, 196 parallel
to each other to keep the cannula 142 in assembled form and to
simultaneously keep the cannula 142 secured to the cage 152 by
keeping the blades 194, 196 from rotating into the unlocked
configuration. When the cannula 142 is secured to the cage 152, the
cannula 142 is in its "docked configuration." When the cannula 142
is removed from the cage 152, the cannula 142 is in its "undocked
configuration."
As shown, the abutment member 144 is generally disc-shaped with a
central opening 212 and an open side 214 that provides access to
the central opening 212. The abutment member 144 also has an
interior recess 216 in communication with the central opening 212.
Furthermore, the abutment member 144 has a pair of arcuate slots
218 that extend around opposing portions of the central opening 212
and are generally coaxial with the central opening 212. The arcuate
slots 218 are sized to receive the first and second blades 194, 196
and to keep the first and second blades 194, 196 generally parallel
to each other, and perpendicular to the abutment member 144. Thus,
the blades 194, 196 are unable to pivot to the unlocked
configuration and the cannula 142 maintains a generally tubular
shape.
After the distal ends 200 of the blades 194, 196 are coupled to the
cage 152, the proximal ends 198 may be inserted through the arcuate
slots 218 of the abutment member 144. Each of the locking ridges
206 has a wedge-like profile. Accordingly, as the locking ridges
206 pass through the arcuate slots 218, the proximal tabs 202 are
urged to bend inward. Once the locking ridges 206 move out of the
arcuate slots 218, the proximal tabs 202 snap back to an
undeflected orientation, and the locking ridges 206 are then
positioned outboard of the arcuate slots 218 to interfere with
withdrawal of the proximal tabs 202 from the arcuate slots 218.
Thus, the proximal tabs 202 act as a locking mechanism that
restricts withdrawal of the abutment member 144 from around the
cannula 142.
After the blades 194, 196 have been inserted into the arcuate slots
218, the abutment member 144 may be positioned at any of a range of
positions along the cannula 142. Thus, upon implantation of the
pedicle screw 150 in the corresponding pedicle, the abutment member
144 will abut the outward-facing surface of the patient's skin
through which the cannula 142 passes. The abutment member 144 helps
to stabilize the cannula 142 with respect to the tissues it passes
through.
Referring to FIG. 8, a perspective view illustrates the connecting
element 140, the cannula 142, the abutment member 144, and the rod
portion 146 of FIG. 7, in assembled form. The shank 162 of the
pedicle screw 150 has been inserted through the aperture 170 such
that the head 160 of the pedicle screw 150 rests against the base
168 of the cage 152. The rod portion 146 has been positioned
between the arms 172 and the set screw 154 has been rotated into
engagement with the threads 166 of the arms 172 to keep the rod
portion 146 in place and restrict further rotation of the cage 152
relative to the pedicle screw 150.
The distal tabs 204 have also been inserted through the slots 174
of the arms 172 of the cage 152, and the blades 194, 196 have been
rotated into the locked configuration. The proximal ends 198 of the
blades 194, 196 have been inserted through the arcuate slots 218 of
the abutment member 144 to keep the blades 194, 196 in assembled
form to define the cannula 142, and to keep the cannula 142 secured
to the cage 152. When one or both of the blades 194, 196 are
oriented in the unlocked configuration, the blades 194, 196 may
still be said to define the cannula 142, although the cannula 142
then has a tapered shape.
Once assembled, the cannula 142 has slots 220 extending along its
entire longitudinal length, along opposite sides of the cannula
142. The slots 220 extend to the cage 152, and are therefore
contiguous with the recesses defined by the arms 172 of the cage
152. Upon implantation of the pedicle screw 150, the slots 220 will
extend along the entire subcutaneous length of the cannula 142.
Therefore, the rod portion 146 may be inserted percutaneously
through the slots 220 along a direction transverse to the axis of
the cannula 146, and may then be moved through the slots 220 along
the anterior direction 16, directly into the trough of the cage
152.
Referring to FIG. 9, a perspective view illustrates a screw
insertion tool 230 according to one embodiment of the invention. In
the embodiment of FIG. 9, the screw insertion tool 230 has a driver
232 designed to rotate the pedicle screw 150 into threaded
engagement with the corresponding tapped pedicle, and a
countertorque member 234 that maintains the orientation of the cage
152 during rotation of the pedicle screw 150.
The driver 232 has a handle 236 designed to be rotated by hand, and
a shank 238 extending from the handle 236. The shank 238 has a
proximal end 240 and distal end 242 shaped to drive the pedicle
screw 150. The distal end 242 has a hexagonal projection 244 that
fits into the hexagonal recess 164 of the head 160 of the pedicle
screw 150. The driver 232 also has a bore 246 sized to receive any
of the guide wires 70, 72, 78; the bore 246 extends through at
least a portion of the shank 238 and, optionally, through all or
part of the handle 236 to permit the screw insertion tool 230 to be
easily guided along each of the guide wires 70, 72, 78.
The countertorque member 234 has a bore 248 that extends along its
entire length, through which the shank 238 of the driver 232
passes. The bore 248 is large enough to permit easy relative
rotation between the driver 232 and the countertorque member 234.
The countertorque member 234 also has a generally tubular shape
with a proximal end 250 and a distal end 252. The proximal end 250
has a plurality of longitudinal ridges 254 designed to be gripped
by a user's fingers to restrict rotation of the countertorque
member 234. The distal end 252 has a plurality of threads 256
designed to threadably engage the threads 178 of the arms 172 of
the cage 152.
Thus, the distal end 252 of the countertorque member 234 can be
rotated into engagement with the cage 152 to secure the
countertorque member 234 to the cage 152, thereby allowing a user
to hold the longitudinal ridges 254 to keep the cage 152 stationary
during rotation of the driver 232. The countertorque member 234
also has longitudinal slots 258 that provide access to the bore 248
of the countertorque member 234 for cleaning or other purposes.
Referring to FIG. 10, a perspective view illustrates the screw
insertion tool 230 of FIG. 9, in engagement with the assembly of
FIG. 8, excluding the rod portion 146 and the set screw 154. The
threads 256 of the distal end 252 have been rotated into engagement
with the threads 178 of the arms 172, and the hexagonal projection
244 has been inserted into the hexagonal recess 164 of the head 160
of the pedicle screw 150. The screw insertion tool 230 is thus
ready to implant the pedicle screw 150 into the corresponding
tapped pedicle.
In the alternative to the embodiment illustrated in FIGS. 9 and 10,
a screw insertion tool may have a countertorque member that
functions independently of threaded engagement with the cage 152.
For example, an alternative countertorque member (not shown) may
have et projections that slide into the recesses between the arms
172, or engage other features of the cage 152, to prevent relative
rotation between the cage 152 and the countertorque member.
Referring to FIG. 11, a perspective view illustrates the screw
insertion tool 230 in use to implant the assembly of FIG. 8,
excluding rod portions 146 and set screws 154, over the first guide
wire 70 of FIG. 2. The handle 236 may be used to actuate the
connecting element 140, the cannula 142, and the abutment member
144 along the first guide wire 70. Upon contact of the pedicle
screw 150 with the tapped pedicle 30 (not shown in FIG. 11), the
handle 236 is rotated while the countertorque member 234 is
restrained from rotation via application of pressure on the
longitudinal ridges 254. Thus, the pedicle screw 150 is rotated
into engagement with the pedicle while keeping the cage 152, the
cannula 142, and the abutment member 144 at a relatively constant
orientation. As shown, the cannula 142 is oriented such that the
slots 220 generally face in the cephalad direction 12 and the
caudal direction 14.
As also shown, a second connecting element 260 has been implanted
in the pedicle 50 of the second vertebra 26 (not shown in FIG. 11).
A second cannula 262 and a second abutment member 264 have been
secured to the second connecting element 260 in a manner similar to
that of the cannula 142 and the abutment member 144. A third
connecting element 270 has been implanted in the pedicle of the
third vertebra (not shown in FIG. 11). A third cannula 272 and a
third abutment member 274 have been secured to the third connecting
element 270 in a manner similar to that of the cannula 142 and the
abutment member 144. The second connecting element 260, cannula
262, and abutment member 264 and the third connecting element 270,
cannula 272, and abutment member 274 may be substantially identical
to the connecting element 140, the cannula 142, and the abutment
member 144, as shown in FIGS. 7 and 8.
Referring to FIG. 12, a perspective view illustrates a fascia
clipping tool 280 according to one embodiment of the invention. As
shown, the fascia clipping tool 280 has a first member 282 and a
second member 284 pivotably secured to the first member 284 through
the use of a pin 286. The first member 282 has a finger loop 288
designed to receive a user's finger, and a blade 290 extending at a
predefined angle from the remainder of the first member 282.
Similarly, the second member 284 has a finger loop 292 and a blade
294. The blades 290, 294 have inwardly-oriented sharp edges that
provide a scissoring effect when the blades 290, 294 are brought
into a parallel configuration.
Referring to FIG. 13, a perspective view illustrates the fascia
clipping tool 280 of FIG. 12 inserted into the cannula 142 of FIG.
11 to sever the adjoining fascia (not shown). The skin between the
cannulas 142, 262, 272 need not be severed; rather, only the
subcutaneous fascia is cut to provide unimpeded percutaneous access
to the cages 152 of the connecting elements 150, 260, 270. The open
side 214 and the interior recess 216 of each of the abutment
members 144, 264, 274 provides the appropriate range of relative
motion in the cephalad and caudal directions 12, 14 for the first
and second members 282, 284 to permit relatively easy cutting of
the fascia with little or no damage to the surrounding tissue (not
shown).
Referring to FIG. 14, a perspective view illustrates a rod
insertion tool 300 according to one embodiment of the invention. As
shown, the rod insertion tool 300 has a handle 302 shaped to be
grasped by hand, and a shank 304 extending from the handle 302. The
handle 302 has a knob 306 that can be rotated by hand to control
retention of a rod (not shown in FIG. 14) by the rod insertion tool
300. The shank 304 has a proximal end 308 secured to the handle 302
and a distal end 310 that receives and is securable to the end of
the rod.
More precisely, the distal end 310 may have a rod coupling 312
securable to the rod through the use of a mechanism such as a
collet or gripper. Such a mechanism may be actuated by rotating the
knob 306. According to alternative embodiments of the invention, an
interference fit or another similar mechanism may be used to retain
the rod in such a manner that the rod can be removed when a
threshold removal force is applied. The shank 304 has a plurality
of slots 314 distributed along the length of the shank 304 to
provide access to a bore (not shown) of the shank 304 for cleaning
or other purposes.
Referring to FIG. 15, a perspective view illustrates the rod
insertion tool 300 of FIG. 14 secured to a rod 316 to facilitate
manual insertion of the rod 316 through the cannulas 142, 262, 272
of FIG. 11. As shown, the rod 316 has a leading end 317 and a
trailing end 318 secured to the rod coupling 312 of the rod
insertion tool 300. Prior to insertion underneath the skin, the rod
316 may be contoured based on the morphology of the patient's spine
so that the rod 316 will maintain the proper lordotic angle between
the first vertebra 24, the second vertebra 26, and the third
vertebra. Alternatively, the rod 316 may be pre-lordosed to provide
a lordotic angle suitable for most patients. The rod 316 may
optionally be selected from a kit (not shown) containing multiple,
differently angled rods.
The leading end 317 is first inserted through the skin (not shown)
of the patient by inserting the leading end 317 through the
proximal end 190 of the cannula 142, and through the central
opening 212 of the abutment member 144. Once underneath the skin,
the handle 302 is manipulated to insert the leading end 317 through
the opening formed in the fascia, through the slots 220 of the
second cannula 262, and through at least one slot 220 of the third
cannula 272 and/or through at least one recess of the cage 152 of
the third connecting element 270. Then, the rod 316 may be detached
from the rod insertion tool 300.
Referring to FIG. 16, a perspective view illustrates a rod seating
tool 320 according to one embodiment of the invention. As shown,
the rod seating tool 320 has a handle 322 shaped to be gripped by
hand, and a shank 324 extending from the handle 322. The shank 324
has a proximal end 326 adjacent to the handle 322 and a distal end
328 shaped to push the rod 316 into place. More precisely, the
distal end 328 may have a blade 330 with a generally thin cross
section. The blade 330 may terminate in an arcuate recess 332 with
a radius matching that of the rod 316.
Referring to FIG. 17, a perspective view illustrates the rod
seating tool 320 of FIG. 16 inserted into the second cannula 262 of
FIG. 11 to help seat the rod 316 in the cages 152 of the connecting
elements 140, 260, 270. As shown, the distal end 328 of the rod
seating tool 320 may simply be inserted through the second cannula
262 until the arcuate recess 332 of the blade 330 abuts the rod
316. Then, pressure is applied via the handle 322 to urge the rod
316 to slide along the slots 220, in the anterior direction 16
until the rod 316 is seated generally within the troughs of the
cages 152 of the connecting elements 140, 260, 270. The distal end
328 may similarly be inserted into the cannula 142, the third
cannula 272, or any combination of the cannulas 142, 262, 272 until
the rod 316 has been positioned to pass through all of the cages
152.
Referring to FIG. 18, a perspective view illustrates a rod holding
tool 18 according to one embodiment of the invention. The rod
holding tool 18 is designed to grip the rod 316 to permit
translation of the rod 316 along its axis or rotation of the rod
316 about its axis. As embodied in FIG. 18, the rod holding tool 18
has first handle 342, a second handle 344, a central body 346, a
shank 348, a pin 350, a first leaf spring 352, a second leaf spring
354, and a pair of screws 356.
The first handle 342 has a proximal end 360 and a distal end 362.
The proximal end 360 has a transverse extension 364 that
facilitates gripping of the first handle 342, for example, with the
fingers of one hand. The proximal end 360 also has a hole 366 with
threads designed to receive threads (not shown) of the
corresponding screw 356. The distal end 362 has a blade 368 that is
pivotably coupled to the central body 346 by the pin 350.
The second handle 344 has a proximal end 370 and a distal end 372.
The proximal end 370 has a hole (not shown) similar to the hole 366
of the proximal end 360 of the first handle 342. The distal end 372
may be formed as a single piece with the central body 346. The
central body 346 has a slot 374 that receives the blade 368 of the
distal end 362 of the first handle 342. The pin 350 passes through
the slot 374 to extend through the blade 368, thereby providing the
pivotable coupling between the central body 346 and the first
handle 342. The central body 346 also has a projection 376 that
extends generally distally.
The shank 348 has a proximal end 380 at which the shank 348 is
secured to the projection 376 of the central body 346, and a distal
end 382 designed to grip the rod 316 in response to pressure
applied to squeeze the first and second handles 342, 344 together.
More precisely, the distal end 382 has an arcuate recess 384 with a
radius matched to that of the rod 316, and an arcuate extension 386
with a radius equal or similar to that of the arcuate recess
384.
The shank 348 also has a stationary arm 387 and a sliding arm 388,
each of which has a generally half-circular cross sectional shape.
The stationary arm 387 is rigidly attached to the projection 376,
and the sliding arm 388 is slidably coupled to the stationary arm
387. The arcuate extension 386 is on the stationary arm 387, and
the arcuate recess 384 is on the sliding arm 388. The sliding arm
388 is coupled to the blade 368 of the first handle 342 within the
central body 346 such that pivotal motion of the first handle 342
urges the sliding arm 388 to slide distally along the stationary
arm 387.
The first leaf spring 352 has a fixed end 390 secured to the first
handle 342 by the corresponding screw 356, and a coupled end 392
coupled to the second leaf spring 354. Similarly, the second leaf
spring 354 has a fixed end 394 secured to the second handle 344 by
the other screw 356, and a coupled end 396 coupled to the coupled
end 392 of the first leaf spring 352. The coupled ends 392, 396 may
be interlocked in an interdigitated manner that permits relative
rotation of the coupled ends 392, 396. Thus, the leaf springs 352,
354 cooperate to provide resilient force urging the first and
second handles 342, 344 to move apart, thereby urging the distal
end 382 of the shank 348 to release the rod 316 in the absence of
force urging the handles 342, 344 together.
In order to use the rod holding tool 340, a portion of the rod 316
may first be positioned to abut the arcuate surface of the arcuate
extension 386. When the first and second handles 342, 344 are
squeezed together, for example, by hand, the sliding arm 388 slides
distally along the stationary arm 387. As the sliding arm 388
slides along the stationary arm 387, the arcuate recess 384 moves
toward the arcuate extension 386 until the arcuate surface of the
arcuate recess 384 is contiguous with the arcuate surface of the
arcuate extension 386. The arcuate recess 384 then cooperates with
the arcuate extension 386 to capture the rod 316 so that the rod
holding tool 340 can be used to axially rotate or translate the rod
316, as desired.
Referring to FIG. 19, a perspective view illustrates the rod
holding tool 340 of FIG. 18 inserted into the second cannula 262 of
FIG. 11 to further manipulate the rod 316. As shown, the distal end
382 of the shank 348 has been inserted through the second cannula
262 to position the arcuate extension 386 adjacent to the rod 316.
The first and second handles 342, 344 have also been squeezed
together to slide the arcuate recess 384 against the rod 316 to
capture the rod 316. Thus, the rod 316 can be translated or rotated
in any direction. More particularly, if the rod 316 is not yet
rotated to the proper orientation to pass properly through the
cages 152, the rod 316 may be rotated axially through the use of
the rod holding tool 340. The rod 316 may also be translated
axially if needed. Fluoroscopy or other known methods may be used
to check the position and orientation of the rod 316 with respect
to the cages 152.
Referring to FIG. 20, a perspective view illustrates a set screw
driver 400 according to one embodiment of the invention. As shown
in FIG. 20, the set screw driver 400 has a handle 402 and a shank
404 extending from the handle 402. The handle 402 has a pair of
oppositely disposed transverse extensions 406 that protrude to
facilitate manual gripping and rotation of the handle 402. The
shank 404 has a proximal end 408 adjacent to the handle 402 and a
distal end 410 designed to transmit torque to the set screw 154.
The distal end 410 may have a hexagonal projection 412 insertable
into the hexagonal recess 180 of the set screw 154.
Referring to FIG. 21, a perspective view illustrates the set screw
driver 400 of FIG. 20 inserted into the cannula 142 of FIG. 11 to
tighten the corresponding set screw 154 to retain the rod 316
within the corresponding cage 152. The set screws 154 may be
applied after the rod 316 has been properly positioned with respect
to the cages 152.
The hexagonal projection 412 may first be inserted into the
hexagonal recess 180 of the set screw 154. Then, the handle 402 may
be gripped and used to insert the set screw 154 into position
adjacent to the threads 178 of the arms 172 of the cage 152 of the
connecting element 140. The handle 402 may then be rotated
clockwise to cause the threads 182 of the set screw 154 to rotate
into engagement with the threads 178. The handle 402 may be rotated
clockwise until the set screw 154 presses firmly against the rod
316 to keep the rod 316 in place within the corresponding cage 152,
and to restrict further rotation of the cage 152 with respect to
the corresponding pedicle screw 150. All three of the set screws
154 may be positioned and tightened in this manner to complete
assembly of the posterior spinal fusion system.
In addition to the set screw driver 400 of FIGS. 20 and 21, a
countertorque member (not shown) may be provided. Such a
countertorque member may engage the cage 152 to keep the cage 152
from rotating while the set screw 154 is tightened.
Referring to FIG. 22, a perspective view illustrates the fully
assembled posterior spinal fusion system including the connecting
elements 140, 260, 270 and the rod 316, with the cannulas 142, 262,
272 still secured to the cages 152 of the connecting elements 140,
260, 270, but with the abutment members 144, 264, 274 removed from
the cannulas 142, 262, 272. The abutment members 144, 264, 274 may
be removed from the cannulas 142, 262, 272 by squeezing the
proximal tabs 202 of each cannula 142, 262, 272 together, for
example, with the thumb and forefinger of a hand. The locking
ridges 206 are thereby moved into alignment with the arcuate slots
218 of the abutment members 144, 264, 274 so that the abutment
members 144, 264, 274 can be withdrawn along the posterior
direction 18 from the corresponding cannulas 142, 262, 272,
respectively.
As mentioned previously, once the abutment members 144, 264, 274
have been removed, the blades 194, 196 of each cannula 142, 262,
272 may be pivoted into the unlocked configuration. The distal tabs
204 may then be withdrawn from the slots 174 of the arms 172 of the
cages 152, and out of the patient's body. Then, the incisions made
to accommodate the cannulas 142, 262, 272 may be closed and treated
through the use of methods known in the art.
Referring to FIG. 23, a perspective view illustrates the completed
posterior spinal fusion system. In addition to the first and second
vertebrae 24, 26, FIG. 23 illustrates a third vertebra 428 superior
to the second vertebra 26. The third vertebra 428 has features
similar to those set forth in the description of the first and
second vertebrae 24, 26. Most pertinently, the third vertebra 428
has pedicles 430 with saddle points 432.
As shown, the pedicle screw 150 of the first connecting element 140
is implanted in the pedicle 30 of the right side of the first
vertebra 24, the pedicle screw 150 of the second connecting element
260 is implanted in the pedicle 50 of the right side of the second
vertebra 26, and the pedicle screw 150 of the third connecting
element 270 is implanted in the pedicle 430 of the right side of
the third vertebra 428. The rod 316 passes through the troughs of
the cages 152 in a manner that preserves the proper lordosis of the
spine 10. The set screws 154 have been rotated into engagement with
the cages 152 and tightened to keep the rod 316 in place within the
troughs of the cages 152 and to substantially eliminate rotation of
the cages 152 relative to their respective vertebrae 24, 26,
428.
The connecting elements 140, 260, 270 thus cooperate with the rod
316 to restrict relative motion of the vertebrae 24, 26, 428 to
form a posterior vertebral fusion system. If desired, a similar
system may be implanted in the left-side pedicles 30, 50, 430 of
the vertebrae 24, 26, 428 through the method set forth previously
to provide a bilateral system. Additionally, the present invention
is not limited to a three-level fusion system, but may be used to
fuse any number of vertebrae together. To fuse more than three
vertebrae together, the steps set forth above may simply be
repeated for each additional vertebra, and the rod may be inserted
through the skin via a first cannula, and then percutaneously
inserted through three or more additional cannulas.
A variety of alternative embodiments of the invention may be used
in place of the method and components illustrated in FIGS. 1-23.
For example, a variety of different connecting elements known in
the art may be used in place of the connecting elements 140, 260,
270 shown and described previously. Polyaxially rotatable cages are
an optional feature of such connecting elements. Cannulas different
from the cannulas 142, 262, 272 set forth above may be used, and
need not be formed of multiple separate pieces, but may instead be
single piece structures. Such cannulas may have slots that
terminate toward their proximal ends.
A variety of different docking elements may be used in place of the
distal tabs 204 and the slots 174. Such docking elements may
include threaded engagement, collets, pin-and-locking-groove
systems, interference fit couplings, snap-fit couplings, and the
like. Additionally, a variety of locking mechanisms may be used in
place of the proximal tabs 202. Such locking mechanisms may include
locking members securable to the proximal ends 190 of the cannulas
142, 262, 272 to interfere with withdrawal of the abutment members
144, 264, 274 therefrom, or locking members movably coupled to the
proximal ends 190. Additionally, a wide variety of interfaces may
be provided between each cannula 142, 262, 272 and the
corresponding abutment member 144, 164, 274 to restrict withdrawal
of the abutment members 144, 264, 274 from the cannulas 142, 262,
272.
Furthermore, each of the instruments set forth previously,
including the screw insertion tool 230, the fascia clipping tool
280, the rod insertion tool 300, the rod seating tool 320, the rod
holding tool 340, and the set screw driver 400, may be replaced
with an alternatively configured tool that performs a similar
function. The steps recited above need not necessarily be performed
in the order provided, but may instead be rearranged, and some
steps may be omitted and/or other steps may be added, to provide
alternative methods within the scope of the invention.
According to one alternative embodiment of the invention, a
connecting element may have a cage pre-attached to a cannula that
provides access to the cage. Such an alternative embodiment will be
shown and described in greater detail in connection with FIG.
24.
Referring to FIG. 24, a perspective view illustrates a cannula 442
and a cage 452 according to one alternative embodiment of the
invention in which the cannula 442 and the cage 452 are initially
secured together. The cage 452 may be part of a connecting element
like the connecting elements 140, 260, 270 set forth previously.
Accordingly, the cage 452 may be polyaxially coupled to a pedicle
screw like the pedicle screw 150 of FIG. 7, and may be designed to
receive a rod portion 146 like that of FIG. 7. The cage 452 may
also receive a set screw 154 like that of FIG. 7 to keep the rod
portion 146 in place and restrain pivotal relative motion between
the cage 452 and the pedicle screw 150.
As shown in FIG. 24, the cage 452 has a base 168 with an aperture
170 designed to receive the pedicle screw 150. The cage 452 has a
pair of arms 472 extending from the base 168. The arms 472 need not
have slots 174 or exterior recesses 176 like the arms 172 of the
cage 152 of FIG. 7. However, each of the arms 472 does have threads
478 that face inward to receive the set screw 154.
The cannula 442 has a generally tubular shape with a proximal end
490 and a distal end 492. The cannula 442 includes a first blade
494 and a second blade 496 positioned opposite the first blade 494.
Each of the blades 494, 496 has a proximal end 498 that is
substantially free, and a distal end 500 pre-attached to the
corresponding arm 472 of the cage 452. In the embodiment of FIG.
24, the distal ends 500 are formed as a single piece with the arms
472, and are separated from the arms 472 by frangible portions 504
of the distal ends 500. The cannula 442 has a pair of slots 520
positioned opposite to each other to permit percutaneous insertion
of the rod 316 therein, as described in connection with the
previous embodiment.
Each frangible portion 504 may take the form of a necked-down
region designed to fracture in response to application of a certain
pre-established threshold linear force or angular moment. More
precisely, each frangible portion 504 may fracture in response to
force tending to tilt the blades 494, 496 to push the proximal ends
498 inward, toward the axis of the cannula 442. Thus, the frangible
portions 504 define a frangible coupling between the cannula 442
and the cage 452.
In use, the cannula 442 and the cage 452 may be used in a manner
similar to that set forth in FIGS. 1-23. However, the cannula 442
and the cage 452 need not be secured together, since they are
formed as a single piece. Additionally, no abutment member may be
necessary, although an abutment member (not shown) somewhat similar
to the abutment member 144 may optionally be used to maintain the
proper relative displacement of the blades 494, 496 during use.
After implantation of the rod 316, removal of the blades 494, 496
from the cage 452 may be accomplished by tilting the blades 494,
496 inward as described previously to fracture the frangible
portions 504, thereby permitting separation of the blades 494, 496
from the cage 452.
According to other alternative embodiments (not shown), blades may
be pre-attached to a cage in a manner that does not require the
blades to be formed as a single piece with the cage. For example,
the blades may be welded, mechanically fastened, or otherwise
pre-attached to the cage. Such embodiments may optionally have
frangible portions. Alternatively, the blades may be removable in
other ways, such as via removal of a mechanical fastener.
The foregoing description discloses a number of different elements
that may be combined in various ways to provide a number of
alternative implantable systems. Although the foregoing examples
relate to implantation of a posterior spinal fusion system, the
present invention may be applied to a wide variety of implants,
within and outside the orthopedic area.
The present invention may be embodied in other specific forms
without departing from its spirit or essential characteristics. It
is appreciated that various features of the systems and methods
described above can be mixed and matched to form a variety of other
alternatives. As such the described embodiments are to be
considered in all respects only as illustrative and not
restrictive. The scope of the invention is, therefore, indicated by
the appended claims rather than by the foregoing description. All
changes which come within the meaning and range of equivalency of
the claims are to be embraced within their scope.
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