U.S. patent number RE42,867 [Application Number 11/799,469] was granted by the patent office on 2011-10-25 for bone fixation system with low profile fastener.
This patent grant is currently assigned to Spinal, LLC. Invention is credited to Robert Doubler, John E. Hammill, Sr..
United States Patent |
RE42,867 |
Hammill, Sr. , et
al. |
October 25, 2011 |
Bone fixation system with low profile fastener
Abstract
A low profile orthopedic device is used to fix and stabilize
bones to correct anomalies in skeletal structure occurring
naturally or by trauma. Bone screws are screwed into bones by
application of torque. Clamps are movably attached to the screws.
Each clamp includes a compression ring. A connecting rod connects
several screws through slots in the clamps. The clamps are
tightened to hold the rod and the heads in a pre-selected position
by linear movement of the compression rings.
Inventors: |
Hammill, Sr.; John E.
(Rossford, OH), Doubler; Robert (Monroe, MI) |
Assignee: |
Spinal, LLC (Toledo,
OH)
|
Family
ID: |
34551408 |
Appl.
No.: |
11/799,469 |
Filed: |
May 9, 2008 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
Issue Date |
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Reissue of: |
10701349 |
Nov 3, 2003 |
7090674 |
Aug 15, 2006 |
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Current U.S.
Class: |
606/277; 606/60;
606/309 |
Current CPC
Class: |
A61B
17/7041 (20130101); A61B 17/7032 (20130101); A61B
17/7037 (20130101); A61B 17/7011 (20130101) |
Current International
Class: |
A61B
17/70 (20060101) |
Field of
Search: |
;606/264,265,266,267,269,270,271,272,277,306,309,60,246 |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
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0 836 835 |
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Jul 1998 |
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EP |
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0836835 |
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Jul 1998 |
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EP |
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0 947 174 |
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May 2001 |
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EP |
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0947174 |
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May 2001 |
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EP |
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Other References
Wright Medical Technology, Inc, Versalok Low Back Fixation
System--Instrumentation Manual, 1997, 1-10, Wright-Medical
Technology, Inc.--Arlington, Tenn. cited by other .
Osteotech Inc. Spinal Systems, Versalok Low Back Fixation
System--Instrumentation Manual, 1999, 1-11, Osteotech, Inc. Spinal
Systems.--Eatontown, New Jersey. cited by other.
|
Primary Examiner: Philogene; Pedro
Attorney, Agent or Firm: Carter, DeLuca, Farrell &
Schmidt, LLP
Claims
We claim:
1. An orthopedic device for stabilizing bones including at least
one bone pin, at least one elongated connector rod and at least one
link interconnecting the elongated connector rod and bone pin, each
bone pin comprising a shank for penetrating a bone with a head on
one end, a clamp universally connected to said head for locking
said pin to a link, said clamp having a body including exterior
walls forming an inner receptacle enclosing said head, a first
compression ring surrounding the outside of said exterior walls in
one position, a slot through said exterior walls of said body
opposite said receptacle, said slot slidably contacting said link,
said first compression ring linearly movable along said outside of
said exterior walls to a second position by application of a force
consisting of a linear force along a longitudinal axis of said body
whereby said exterior walls of said receptacle and said slot exert
compressive force securely locking said clamp about said head and
said link, said link having an arm with one end and a journal at
the other end, said journal has a split sleeve and a second
compression ring surrounding the outside of said split sleeve, said
second compression ring being movable linearly along said split
sleeve by application of a force consisting of a linear force along
an axis of said link to move said sleeve from an open position to a
closed position, said open position permitting adjustment of said
connector rod in said journal and said closed position securing
said connector rod and journal together.
2. An orthopedic device of claim 1 wherein said head of said bone
pin is approximately spherical and said receptacle has a
complementary shape whereby said bone pin and said clamp may be
universally oriented.
3. An orthopedic device of claim 1 wherein said shank is formed
with an exterior helical thread.
4. An orthopedic device of claim 1 wherein said slot is adjacent
said receptacle whereby said head and said link are in close
proximity producing a low profile.
5. In an orthopedic system for stabilizing and fixing bones across
a discontinuity, at least two bone screws, an elongated connector
rod of a length to span the discontinuity, and at least one link,
each said bone screw comprising a threaded shank with a head, said
head including a means for applying torque to said shank and a
means for attaching one end of said link, the other end of said
link formed as a clamp, said clamp having an elongated body with
exterior walls, a slot extending across said exterior walls of said
clamp, said connector rod movably disposed in said slot, a
compression ring surrounding said exterior walls in one position
linearly along said exterior walls to a second position by
application of a force consisting of a linear force along a
longitudinal axis of said link whereby said exterior walls exert a
compressive force in said slot when said compression ring is moved
by said linear force to said second position.
6. In an orthopedic system of claim 5 wherein said connector rod is
slidably engaged in said slot when said compression ring is in said
one position, said connector rod is held in said slot when said
compression ring is in said second position.
.Iadd.7. In an orthopedic device for stabilizing bones comprising
in combination a bone pin having a first end and a second end, said
first end constructed and arranged as a shank portion for
securement to a bone, said second end constructed and arranged as a
head portion, a clamp universally connected to said head portion of
said bone pin, said clamp having an elongated body with exterior
walls, a slot extending across said exterior walls, said slot
constructed and arranged to accept a rod member, a compression ring
surrounding said exterior walls, said compression ring linearly
traversable along said exterior walls between a first position and
a second position by a force consisting of a linear force, whereby
traversal of said compression ring from said first position to said
second position compresses said clamp to substantially fix said
clamp and said rod to said bone pin in a predetermined orientation,
the improvement comprising: at least one annular bulge positioned
along the length of said exterior walls of said clamp to provide a
change in the external diameter along the length thereof, said at
least one annular bulge constructed and arranged to cooperate with
said compression ring to apply compressive forces to said clamp for
immobilizing at least one of the connections between said clamp and
said rod or said clamp and said bone pin..Iaddend.
.Iadd.8. The orthopedic device for stabilizing bones of claim 7
wherein said compression ring includes at least one inner annular
ridge constructed and arranged to engage said at least one annular
bulge in an overlapping manner while said compression ring is in
said second position, whereby engagement of said bulge and said
ridge applies compressive forces to said clamp for immobilizing the
connections between said clamp and said rod with respect to said
bone pin..Iaddend.
.Iadd.9. The orthopedic device for stabilizing bones of claim 7
wherein the at least one annular bulge is constructed and arranged
to cooperate with said compression ring to apply compressive forces
to said clamp for immobilizing the connections between said clamp
and said rod, the at least one annular bulge constructed and
arranged to cooperate with said compression ring to apply
compressive forces to said clamp for immobilizing the connections
between said clamp and said bone pin, said compression ring
constructed and arranged to progressively engage said annular
bulge, whereby said connections may be immobilized one at a
time..Iaddend.
.Iadd.10. The orthopedic device for stabilizing bones of claim 9
wherein said compression ring includes at least one inner annular
ridge constructed and arranged to engage the at least one annular
bulge in an overlapping manner while said compression ring is in
said second position..Iaddend.
.Iadd.11. The orthopedic device for stabilizing bones of claim 7,
wherein the first position is defined when the compression ring is
adjacent the head portion of the bone pin..Iaddend.
.Iadd.12. The orthopedic device for stabilizing bones of claim 7
wherein said bone pin is a bone screw wherein said first end
includes at least one helical thread for penetrating and engaging a
bone and wherein said head portion is substantially spherical in
shape..Iaddend.
.Iadd.13. An orthopedic device for stabilizing bones comprising: a
bone pin having a first end and a second end, said first end
constructed and arranged as a shank portion for penetrating
securement to a bone, said second end constructed and arranged as a
head portion; a clamp universally connected to said head portion of
said bone pin for securing said bone pin to a rod or link member,
said clamp having an elongated body with exterior walls, said
exterior walls including at least one annular bulge to provide a
change in the external diameter of said exterior walls, a slot
extending across said exterior walls, said slot constructed and
arranged to accept said rod or said link member; a compression ring
surrounding said exterior walls, said compression ring linearly
traversable along said exterior walls between a first position and
a second position by application of a force consisting of a linear
force along a longitudinal axis of said clamp, whereby traversal of
said compression ring from said first position to said second
position causes said compression ring to cooperate with said at
least one annular bulge to apply compressive forces to said clamp
to immobilize at least one of the connections between said clamp
and said rod or link member or said clamp and said bone
pin..Iaddend.
.Iadd.14. The orthopedic device for stabilizing bones of claim 13
wherein said compression ring includes at least one inner annular
ridge constructed and arranged to engage said at least one annular
bulge in an overlapping manner while said compression ring is in
said second position, whereby engagement of said at least one bulge
and said at least one ridge applies compressive forces to said
clamp for immobilizing at least one of said
connections..Iaddend.
.Iadd.15. The orthopedic device for stabilizing bones of claim 13
wherein said at least one annular bulge is constructed and arranged
to cooperate with said compression ring to apply compressive forces
to said clamp for immobilizing at least one of said
connections..Iaddend.
.Iadd.16. The orthopedic device for stabilizing bones of claim 15
wherein the at least one annular bulge is constructed and arranged
to cooperate with said compression ring while said compression ring
is in said second position to immobilize the connection between
said clamp and said bone pin said second bulge constructed and
arranged to cooperate with said compression ring to immobilize the
connection between said clamp and said rod or link member while
said compression ring is in said second position, whereby said
compression ring may independently engage said first or said second
bulges during translation thereof..Iaddend.
.Iadd.17. The orthopedic device for stabilizing bones of claim 15
wherein said compression ring includes at least one inner annular
ridge constructed and arranged to engage the at least one annular
bulge in an overlapping manner while said compression ring is in
said second position, whereby engagement of said annular bulge and
said annular ridge applies compressive forces to said clamp for
immobilizing said connections..Iaddend.
.Iadd.18. The orthopedic device for stabilizing bones of claim 17
wherein the first position is defined when the compression ring is
adjacent the head portion of the bone pin..Iaddend.
.Iadd.19. The orthopedic device for stabilizing bones of claim 13
wherein said bone pin is a bone screw wherein said first end
includes at least one helical thread for penetrating and engaging a
bone and wherein said head portion is at least partially spherical
in shape..Iaddend.
.Iadd.20. An orthopedic kit for stabilizing bones comprising: at
least one bone pin having a first end and a second end, said first
end constructed and arranged as a shank portion for penetrating
securement to a bone, said second end constructed and arranged as a
head portion; a clamp universally connected to said head portion of
each said bone pin for securing said bone pin to a rod or a link,
said clamp having an elongated body with exterior walls, a slot
extending across said exterior walls, said slot constructed and
arranged to slidably accept said rod or said link; a first
compression ring surrounding said exterior walls of said clamp,
said first compression ring linearly traversable along said
exterior walls between a first position and a second position by a
force consisting of a linear force along a longitudinal axis of
said clamp, said first position permitting adjustment of said rod
or link, said second position compressing said clamp to immobilize
said rod or link with respect to said bone pin; at least one link
having an arm on one end and a journal at the other end, said
journal having a split sleeve and a second compression ring
surrounding an outer surface of said split sleeve, said second
compression ring being movable linearly along said split sleeve by
application of a force consisting of a linear force along a
longitudinal axis of said link to move said sleeve from an open
position to a closed position, said open position permitting
adjustment of said connector rod in said journal and said closed
position securing said connector rod and said journal together; at
least one elongated connector rod constructed and arranged to
cooperate with said slot or said journal..Iaddend.
.Iadd.21. The orthopedic kit for stabilizing bones of claim 20
wherein said clamp includes at least one annular bulge positioned
along the length of said exterior walls thereof to provide a change
in the external diameter of said clamp, said at least one annular
bulge constructed and arranged to cooperate with said first
compression ring to apply compressive forces to said clamp for
immobilizing the connections between said clamp and said rod or
said link with respect to said bone pin..Iaddend.
.Iadd.22. The orthopedic kit for stabilizing bones of claim 21
wherein said exterior walls of said clamp include two or more
annular bulges to provide a change in the external diameter along
the length of said exterior walls, said two or more annular bulges
constructed and arranged to cooperate with said first compression
ring to apply compressive forces to said clamp for immobilizing the
connections between said clamp and said rod or said link with
respect to said bone pin..Iaddend.
.Iadd.23. The orthopedic kit for stabilizing bones of claim 22
wherein a first of said two or more annular bulges is positioned at
a first end of said clamp and second of said two or more annular
bulges is positioned at second end of said clamp, said first bulge
constructed and arranged to cooperate with said first compression
ring while said first compression ring is in said second position
to immobilize the connection between said clamp and said bone pin
said second ring constructed and arranged to immobilize the
connection between said clamp and said rod or said link while said
compression ring is in said second position..Iaddend.
.Iadd.24. The orthopedic kit for stabilizing bones of claim 22
wherein said first compression ring includes at least one inner
annular ridge constructed and arranged to engage at least one of
said two or more annular bulges in an overlapping manner while said
first compression ring is in said second position, whereby
engagement of said bulge and said ridge applies compressive forces
to said clamp for immobilizing the connections between said clamp
and said rod or said link with respect to said bone
pin..Iaddend.
.Iadd.25. The orthopedic kit for stabilizing bones of claim 24
wherein said first compression ring includes two or more inner
annular ridges, at least one of said ridges constructed and
arranged to fit between said two or more annular bulges of said
clamp while said compression ring is in said first position and at
least one of said ridges constructed and arranged to engage at
least one of said two or more annular bulges in an overlapping
manner while said compression ring is in said second position to
provide compressive forces to said clamp..Iaddend.
.Iadd.26. The orthopedic kit for stabilizing bones of claim 20
wherein said bone pin is a bone screw wherein said first end
includes at least one helical thread for penetrating and engaging a
bone and wherein said head portion is substantially spherical in
shape..Iaddend.
.Iadd.27. A method of using an orthopedic device to stabilize bones
across a discontinuity comprising the steps of: providing a first
bone pin having a first end and a second end, said first end
constructed and arranged as a shank portion for penetrating
securement to a bone, said second end constructed and arranged as a
head portion; connecting a first clamp member to said head portion
of said first bone pin for universal movement therebetween, said
first clamp member having an elongated body with exterior walls, a
first compression ring surrounding said exterior walls, said first
compression ring located in a first position, a first slot
extending across said exterior walls, said first slot constructed
and arranged to accept a rod member; securing said shank portion of
said first bone pin to a first bone portion on a first side of said
discontinuity; providing a second bone pin having a first end and a
second end, said first end constructed and arranged as a shank
portion for penetrating securement to a bone, said second end
constructed and arranged as a head portion; connecting a second
clamp member to said head portion of said second bone pin for
universal movement therebetween, said second clamp member having an
elongated body with exterior walls, a second compression ring
surrounding said exterior walls, said second compression ring
located in a first position, a second slot extending across said
exterior walls, said second slot constructed and arranged to accept
a rod member; securing said shank portion of said second bone pin
to a second bone portion on a second side of said discontinuity;
placing a rod member in said first and said second slots, whereby
said rod member extends across said discontinuity; applying a force
consisting of a linear force along the longitudinal centerline of
said first clamp member for traversing said first compression ring
to a second position along said exterior walls of said first clamp
member to compress said first clamp member to substantially fix
said first clamp and said rod member in a predetermined orientation
with respect to said first bone pin; applying a force consisting of
a linear force along the longitudinal centerline of said second
clamp member for traversing said second compression ring to a
second position along said exterior walls of said second clamp
member to compress said second clamp member to substantially fix
said second clamp member and said rod member in a predetermined
orientation with respect to said first bone pin; whereby said bones
are stabilized across said discontinuity..Iaddend.
.Iadd.28. The method of using an orthopedic device to stabilize
bones across a discontinuity of claim 27 wherein said first and
said second bone pins are bone screws wherein said first end of
each includes at least one helical thread for penetrating and
engaging a bone and wherein said head portion of each is
substantially spherical in shape..Iaddend.
.Iadd.29. The method of using an orthopedic device to stabilize
bones across a discontinuity of claim 27 wherein said exterior
walls of said first and said second clamp each include at least one
annular bulge to provide a change in the external diameter along
the length of said exterior walls, said at least one annular bulge
constructed and arranged to cooperate with each said respective
compression ring to apply compressive forces to said respective
clamp for immobilizing the connections between each said respective
clamp and said rod with respect to each said respective bone
pin..Iaddend.
.Iadd.30. The method of using an orthopedic device to stabilize
bones across a discontinuity of claim 29 wherein said first and
said second compression ring each include at least one inner
annular ridge constructed and arranged to engage said at least one
annular bulge of a respective clamp in an overlapping manner while
each said respective compression ring is located in said second
position, whereby engagement between said respective bulges and
said ridges apply compressive forces to said respective clamp for
immobilizing the connections between said respective clamp and said
rod with respect to said respective bone pin..Iaddend.
.Iadd.31. An apparatus comprising: a bone screw having a threaded
shaft and a screw head; a clamp body having a receptacle sized to
accommodate the head of the bone screw with the threaded shaft
extending downwardly out of the receptacle; and a compression ring
around exterior walls of the clamp body and movable along the
exterior walls from an open position to a closed position, the
compression ring including an annular flange at the upper edge
thereof, the open position defined when the compression ring is
moved towards the receptacle..Iaddend.
.Iadd.32. The apparatus of claim 31 wherein the screw head is
spherical..Iaddend.
.Iadd.33. The apparatus of claim 32 wherein the receptacle is
configured to receive the spherical screw head..Iaddend.
.Iadd.34. The apparatus of claim 31 wherein the receptacle is
slotted..Iaddend.
.Iadd.35. The apparatus of claim 31 wherein the clamp body has
annular bulges which engage annular ridges on the inside of the
compression ring with the compression ring in the closed
position..Iaddend.
.Iadd.36. The apparatus of claim 31 wherein the connection between
the screw and the clamp body is a universal connection and the
orientation of the screw relative to the clamp body is adjustable
with the compression ring in the open position and the orientation
between the screw and the clamp body is fixed with the compression
ring in the closed position..Iaddend.
.Iadd.37. The apparatus of claim 31 wherein the clamp body further
comprises a slot to receive a connector rod..Iaddend.
.Iadd.38. The apparatus of claim 37 wherein the slot has upper and
lower longitudinal ridges to grip the connector rod..Iaddend.
.Iadd.39. The apparatus of claim 37 wherein the position of the rod
in the slot is adjustable with the compression ring in the open
position and is fixed with compression ring in the closed
position..Iaddend.
.Iadd.40. An apparatus comprising: a bone screw having a threaded
shaft and a screw head; a clamp body having a receptacle sized to
accommodate the head of the bone screw with the threaded shaft
extending out the bottom of the clamp body, the clamp body having a
slot to receive a rod; a compression ring around exterior walls of
the clamp body and movable along the exterior walls from an open
position in which the position of the screw relative to the clamp
body is adjustable to a closed position in which the position of
the screw relative to the clamp body is fixed; and a retainer which
extends across and covers the slot, the retainer remaining
rotationally stationary with respect to the clamp body during
relative movement of the clamp body and the compression
ring..Iaddend.
.Iadd.41. The apparatus of claim 40 wherein the retainer is a
ring..Iaddend.
.Iadd.42. The apparatus of claim 41 wherein the retainer snaps into
a groove on the clamp body..Iaddend.
.Iadd.43. The apparatus of claim 41 wherein the retainer is a
clip..Iaddend.
.Iadd.44. The apparatus of claim 43 wherein the ends of the clip
seat into a groove of the clamp body..Iaddend.
.Iadd.45. An apparatus comprising: a bone screw having a threaded
shaft and a screw body; a clamp body having a lower portion
defining a receptacle sized to accommodate the head of the bone
screw and an upper portion sized to accommodate a rod, the clamp
body defining a first diameter near the receptacle and a second
diameter near the upper portion, the first diameter being less than
the second diameter; a compression ring around exterior walls of
the clamp body and movable along the exterior walls from an open
position in which the orientation of the screw is adjustable
relative to the clamp body and a closed position in which the
orientation of the screw is fixed relative to the clamp body, the
open position defined when the compression ring is moved towards
the receptacle; and a retainer for holding a connector rod and the
clamp body together..Iaddend.
.Iadd.46. The apparatus of claim 45 wherein the retainer is a set
screw retainer..Iaddend.
.Iadd.47. The apparatus of claim 45 wherein the clamp body includes
a bore for receiving a rod..Iaddend.
.Iadd.48. The apparatus of claim 47 wherein the clamp body includes
a threaded passage which intersects the bore..Iaddend.
.Iadd.49. The apparatus of claim 48 wherein the threaded passage is
configured to receive a set screw retainer..Iaddend.
.Iadd.50. The apparatus of claim 48 further including a set screw
retainer receivable in the threaded passage for holding a rod
disposed in the bore and the clamp together..Iaddend.
.Iadd.51. An apparatus comprising: a bone screw having a head at
one end thereof; a clamp body having a receptacle for receiving the
head of the bone screw, the receptacle being transitionable between
a first state and a second state; a retainer engageable with the
clamp body to hold a connector rod in a relative position with
respect to the clamp body; and a ring member operably associated
with the clamp body and repositionable from a first position to a
second position, the first position defined when the ring member is
adjacent the receptacle wherein: when the ring member is in the
first position, the receptacle is in the first state and the bone
screw is axially adjustable relative to the receptacle, and when
the ring member is in the second position, the receptacle is in the
second state and the bone screw is fixed relative to the
receptacle..Iaddend.
.Iadd.52. The apparatus of claim 51 wherein the clamp body includes
a saddle for retaining a connector rod..Iaddend.
.Iadd.53. The apparatus of claim 51 wherein the ring member is
slidably disposed on an outer surface of the clamp
body..Iaddend.
.Iadd.54. The apparatus of claim 51 wherein the clamp body includes
a slot such that opposing walls of the clamp body are
repositionable towards and away from each other..Iaddend.
.Iadd.55. The apparatus of claim 54 wherein when the ring member is
in the second position, the opposing walls of the clamp body are
urged towards each other and frictionally engage the head of the
bone screw..Iaddend.
.Iadd.56. The apparatus of claim 51 wherein the retainer is a
clip..Iaddend.
.Iadd.57. The apparatus of claim 51 wherein the retainer is a set
screw..Iaddend.
.Iadd.58. An apparatus comprising: a bone screw having a head at
one end thereof; a clamp body having a receptacle for receiving the
head of the bone screw, the receptacle transitionable between a
first state and a second state; a retainer engageable with the
clamp body; a slot defined between the receptacle and the retainer
for receiving a connector rod, the retainer holding the connector
rod in the slot; and a ring member operably associated with the
clamp body such that when the ring member is in a first position
the bone screw is axially adjustable relative to the receptacle,
and when the ring member is in a second position the bone screw is
fixed relative to the receptacle, the first position defined when
the ring member is adjacent the receptacle of the clamp
body..Iaddend.
.Iadd.59. The apparatus of claim 58, wherein the clamp body
includes a saddle, the saddle and the retainer defining the
slot..Iaddend.
.Iadd.60. The apparatus of claim 58, wherein when the ring member
is in the second position, the receptacle frictionally engages the
head of the bone screw..Iaddend.
.Iadd.61. The apparatus of claim 58, wherein the receptacle
includes opposing walls that are repositionable towards and away
from each other..Iaddend.
.Iadd.62. The apparatus of claim 51, wherein the opposing walls
frictionally engage the head of the bone screw when the ring member
is in the second position..Iaddend.
.Iadd.63. The apparatus of claim 58, wherein the retainer is a
clip..Iaddend.
.Iadd.64. The apparatus of claim 58, wherein the retainer is a set
screw..Iaddend.
.Iadd.65. The apparatus of claim 58, wherein the ring member is
disposed on an outer surface of the clamp body..Iaddend.
.Iadd.66. The apparatus of claim 58, wherein the clamp body
includes a slot such that opposing walls of the clamp body are
repositionable..Iaddend.
.Iadd.67. The apparatus of claim 31, wherein the bone screw is
pivotable relative to the clamp body when the compression ring is
in the open position..Iaddend.
.Iadd.68. The apparatus of claim 31, wherein said compression ring
includes at least one annular ridge and the clamp body includes at
least annular bulge, the annular ridge and the annular bulge engage
in an overlapping manner while said compression ring is in said
second position, whereby engagement of the annular bulge and the
annular ridge applies compressive forces to said clamp for
immobilizing said connections..Iaddend.
.Iadd.69. The apparatus of claim 31, wherein the annular flange
extends radially outward..Iaddend.
.Iadd.70. A method of using an orthopedic device to stabilize bones
across a discontinuity, comprising: providing a first bone pin
assembly, the first bone pin assembly including a first bone screw
having a threaded shaft and a screw head, a first clamp body having
a receptacle at one end and a first slot at an opposing end, the
receptacle sized to accommodate the head of the first bone screw
with the threaded shaft extending downwardly out of the receptacle,
and a first compression ring around exterior walls of the first
clamp body and movable along the exterior walls between an open
position and a closed position, the first compression ring
including an annular flange at the upper edge thereof, the open
position defined when the first compression ring is adjacent the
receptacle such that the first bone screw is pivotable relative to
the first clamp body; securing the threaded shaft of the first bone
pin assembly to a first bone portion on a first side of the
discontinuity; placing a rod member in the first slot, whereby the
rod member extends across the discontinuity; and repositioning the
first compression ring from its open position to its closed
position..Iaddend.
.Iadd.71. The method of using an orthopedic device to stabilize
bones across a discontinuity of claim 70 wherein the exterior wall
of the first clamp body includes at least one annular bulge
cooperative with the first compression ring to apply compressive
forces to the first clamp body for immobilizing the connection
between the first clamp body and the rod with respect to the first
bone screw..Iaddend.
.Iadd.72. The method of using an orthopedic device to stabilize
bones across a discontinuity of claim 70, further comprising a
second bone pin assembly, the second bone pin assembly including a
second bone screw having a threaded shaft and a screw head, a
second clamp body having a receptacle at one end and a second slot
at an opposing end, the receptacle sized to accommodate the head of
the second bone screw with the threaded shaft extending downwardly
out of the receptacle, and a second compression ring around
exterior walls of the second clamp body and movable along the
exterior walls between an open position and a closed position, the
second compression ring including an annular flange at the upper
edge thereof, the open position defined when the second compression
ring is adjacent the receptacle such that the second bone screw is
pivotable relative to the second clamp body..Iaddend.
.Iadd.73. The method of using an orthopedic device to stabilize
bones across a discontinuity of claim 72, further including:
securing the threaded shaft of the second bone pin assembly to a
second bone portion on a second side of the discontinuity; and
repositioning the second compression ring from its open position to
its closed position..Iaddend.
Description
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to orthopedic surgery and, in particular, to
devices and prosthesis for stabilizing and fixing bones and joints
of the body.
2. Description of the Prior Art
Published U.S. Application, US 2003/0149487 A1, published Aug. 7,
2003, teaches the use of a linear movement to apply compressive
forces to connect components of an artificial hip joint.
U.S. Pat. No. 6,626,906 issued Sep. 30, 2003 to Young teaches a
spinal rod attached to a spinal anchor by a clamp. The clamp is
tightened about the anchor by a collet screwed into the clamp. The
rod is held in the clamp by a split ring that is reduced in size by
the collet. The anchor is placed in the bone by torque and the
collet is tightened by additional torque.
U.S. Pat. No. 6,610,063 issued Aug. 26, 2003 to Kumar et al, U.S.
Pat. No. 6,610,062 issued Aug. 26, 2003 to Bailey et al, U.S. Pat.
No. 6,565,565 issued May 20, 2003 to Yuan et al, U.S. Pat. No. RE
37,665 issued Apr. 16, 2002 to Ralph et al, U.S. Pat. No. 6,478,798
issued Nov. 12, 2002 to Howland and U.S. Pat. No. 5,584,834 issued
Dec. 17, 1996 to Errico et al teach a spinal rod coupled to several
bone anchors by clamps that require additional torque to be applied
to the assembly after the bone screw has been seated in the
bone.
In normal practice, the bone screws are each anchored in the bone
with a specific amount of torque that approaches the ultimate
sustainable force between the screw threads and the bone. The bone
screws are then connected together by a rod having sufficient
stiffness to maintain the desired skeletal orientation. The
connection between the rod and the bone screws must be strong
enough to be immobile.
All these prior art spinal fixation devices result in additional
torque applied to the assembly, and thereby to the bone screw, to
tighten and lock the rod to each of the bone screws. The additional
load may strip the purchase between the bone and the threads of the
bone screw. To prevent such a result, some tool must be used to
counter the torque of locking the rod and the screws. The use of an
anti-torqueing tool requires additional coordination by the surgeon
or surgeons to prevent slippage.
What is needed in the art is a system for connecting a rod and an
embedded bone screw using compressive forces rather than
torque.
SUMMARY OF THE PRESENT INVENTION
There are many instances in which it is necessary to stabilize and
fix bones and bone fragments in a particular spatial relationship
to correct the location of skeletal components due to injury or
disease. One group of devices employ a number of bone pins,
anchors, or screws placed in bones across a discontinuity in the
bone or bone fragments, such as a fracture, or adjacent vertebrae,
or a joint, connected by a rod to maintain a predetermined spatial
location of the bones. In some cases these devices may be
temporary, with subsequent removal, or permanent, in the form of a
prosthesis. The devices may be internal or external of the body.
The instant device may be used in these applications. However, the
preferred embodiment is related to spinal fixation and the
description is directed thereto by way of example and not
limitation.
SHORT DESCRIPTION OF THE DRAWINGS
FIG. 1 is a perspective of a portion of the spine with the
orthopedic device of this invention in place;
FIG. 2 is a perspective of one embodiment of the orthopedic device
of this invention;
FIG. 3 is an end view, partially in section, of the orthopedic
device of this invention with the compression ring in the open
position;
FIG. 4 is an end view, partially in section, of the orthopedic
device of this invention with the compression ring in the closed
position;
FIG. 5 is a cross section of FIG. 3;
FIG. 6 is a cross section of FIG. 4;
FIG. 7 is a top plan view of the clamp body of this invention;
FIG. 8 is a side view, partially in section, of the clamp body of
this invention;
FIG. 9 is a perspective of the clamp body of this invention;
FIG. 10 is a perspective of the compression ring of this
.[.invnetion.]. .Iadd.invention.Iaddend.;
FIG. 11 is a top view of the compression ring of this
invention;
FIG. 12 is a cross section of the compression ring of this
invention;
FIG. 13 is a perspective of another embodiment of this
invention;
FIG. 14 is a perspective of another embodiment of this
invention;
FIG. 15 is a perspective of another embodiment of this
invention;
FIG. 16 is a cross section of FIG. 15 showing the compression ring
in the open position;
FIG. 17 is a cross section of FIG. 15 showing the compression ring
in the closed position;
FIG. 18 is a perspective of another embodiment of this invention
with the compression ring in the open position;
FIG. 19 is a side view of FIG. 18 with the compression ring in the
closed position;
FIG. 20 is a perspective of another embodiment of this invention
with the compression ring in the open position;
FIG. 21 is a side view of FIG. 20 with the compression ring in the
closed position;
FIG. 22 is a perspective of another embodiment of this invention;
and
FIG. 23 is a cross section of FIG. 22.
DETAILED DESCRIPTION OF THE INVENTION
FIG. 1 illustrates a portion of the lumbar spine S with a
unilateral orthopedic fixation device 10 in place to stabilize and
fix the vertebra in relation to each other and the sacrum in order
to maintain a more natural curvature. A bilateral installation can
be used, if deemed necessary. As shown in more detail in FIG. 2, an
elongated connector bar 11 spans the discontinuity between the
vertebra and bone screws 13. As shown, the bar has a circular cross
section however, other shapes may be used, such as shown for the
link 29 in FIG. 13. The bone anchors have an exterior helical
thread 60, shown in FIGS. 5-6, by which the bone screws 13 gain
purchase in the cancellous bone through application of torque.
The torque is applied to the screws by the surgeon using a tool
(not shown) that engages the recess 61 in the head 15 of the screw
and rotates the screw about its longitudinal axis. The amount of
torque is critical to installation and the long life of the
prosthesis in that too little does not secure the screw from
loosening or backing out and too much causes the stripping of the
thread path in the bone and loss of purchase. The surgeon attempts
to apply the optimum torque when placing the screws in the bone and
additional torque on the bone screw is to be avoided. As shown in
FIGS. 5 and 6, the recess 61 is accessible through the clamp body
12 which permits pre-assembly of the screw and clamp, if desired,
before placement in the bone.
During the spinal fixation, the several bone screws are threaded
into the different vertebrae according to the anatomy of each
vertebrae. This results in a series of screws without uniformity in
angle or alignment. To compensate for these anomalies, the
connection between the head of the screws and the clamp bodies
pivots or swivels to capture the connector rod. In some instances,
the rod must be bent because the screws are so far out of line or
the intended correction is so severe. In other cases, a link may be
used to secure the rod relative to the bone screw. To avoid
application of any more torque to the bone screw, the connector rod
11 is secured to the bone screw by a linear motion which applies
compressive force through clamp 12 to the rod 11 and the head 15 of
the screw.
The exterior walls 24 of the clamp body 12 are illustrated as
generally tubular with a receptacle 25, shown in FIG. 8, at one end
and a slot 23 at the other end. The receptacle is of a size to
accommodate the head 15 of the bone screw. The slot 23 has upper
and lower longitudinal ridges 17 and 18, respectively, to grip the
connector rod 11. As shown in FIGS. 5 and 6, the head 15 is
spherical and the inside surface 16 of the receptacle is
complementary to permit a universal or swivel connection. The
orthopedic device has a low profile because the connector rod is
recessed in the slot 23 of clamp 12.
The exterior walls 24 of clamp 12 may be tapered or otherwise
shaped to provide a change in external diameter along the length.
The walls 24 also are relieved with circumferential slots 27 and
28, shown in FIGS. 8-9, to increase the radial flexibility of the
clamp. A compression ring 14 is force fit on the exterior walls 24
of the clamp 12 by flexing the tubular walls. The compression ring
14 is moveable along the exterior walls from an open position to a
closed position. The open position, as shown in FIGS. 5, 18, and
20, allows swiveling movement of the screw head and sliding
movement of the connector rod within the clamp 12. In the closed
position, shown in FIGS. 6, 19 and 21, the compression ring 14
applies compressive forces between the clamp 12 and the rod 11 and
screw 13 that immobilizes the connections. The compression ring
.[.12.]. .Iadd.14 .Iaddend.has a skirt 26 with spaced inner annular
ridges 19 and 22 which engage annular bulges .[.19.]. .Iadd.20
.Iaddend.and 21, respectively, on the exterior walls 24 of clamp 12
in the closed position.
The application of the compressive force that immobilizes the
components of the orthopedic device is generated by a linear
movement of the compression ring relative to the exterior walls of
the clamp. This movement to the closed position is accomplished
using a simple telescoping instrument (not shown) engaging the
clamp and the compression ring so that equal and opposite forces
moves the ring without imparting stress to the screw. In the event
of remedial surgery, the clamp may be moved to the open position in
the same manner.
The link 29, shown in FIG. 13, extends the range of the orthopedic
device in situations where the connector rod cannot directly
contact the slot 23 in the clamp 12. The link may come in different
lengths or be customized to the size necessary for a particular
patient. The link 29 has an arm similar to the dimensions of a
connector rod but of a trapezoidal shape though other shapes may be
used. The arm has a journal 30 on one end. The journal 30 is shown
as a closed ring however, it may be discontinuous. The journal has
a threaded bore with a set screw 31 to secure the link to the
connector rod. The other end of the link is secured to the bone
screw by the clamp 12 and compression ring 14. In FIG. 14, the link
29' arm is the same or similar in shape to a connector rod. The
link has a journal 30' with a set screw 31' to fix the connection
with the connector rod 11.
In FIGS. 15, 16, and 17 another link 29'' is illustrated with a
journal 30'' at one end. The link is similar to a connector rod.
The journal 30'' is a split sleeve with a compression ring 14'
encircling the split sleeve. The compression ring 14' has an open
position, shown in FIG. 17, and a closed position, shown in FIG.
16. After adjusting the connection between the link and the
connector rod 11, the compression ring is moved to the closed
position to secure the link to the connector rod. The other end of
the link 29'' is secured in the slot of the clamp 12 to complete
the tightening of the orthopedic device.
FIGS. 18-23 illustrate embodiments of the orthopedic device 10 in
which the clamp 12 includes a retainer preventing the inadvertent
separation of the connector rod 11 from the clamp. The use of these
clamps and retainers is discretionary with the surgeon. In FIGS. 18
and 19, the exterior walls of the clamp 12 extend above the slot 23
as opposing semi-circular projections. An exterior groove 41 is
formed in the semi-circular projections resulting in a terminal lip
42. A retainer ring 40 is snapped into and held in place by the
groove 41.
FIGS. 20 and 21 illustrate another retainer in the form of a clip
50 which extends across and covers the open slot 23. The ends 53 of
the clip are reverse folded to snap over the lip 52 and seat into
the groove 51.
FIGS. 22 and 23 illustrate a clamp 12' with a bore 23' for passage
of the connector rod 11. The bore 23' is intersected by a threaded
passage 60 with a set screw retainer 61 for holding the connector
rod 11 and the clamp 12' together. After the rod 11 is passed
through the clamps of an orthopedic device, the compression rings
would be moved to the closed position locking the orientation of
the rods and screws. The set screws would then be tightened to fix
the rod to the clamp. In this way, the torque of tightening the set
screw would be absorbed by the rod. The clamp 12' is locked to the
screw 13 by compression ring 14, shown in the closed position.
A number of embodiments of the present invention have been
described. Nevertheless, it will be understood that various
modifications may be made without departing from the spirit and
scope of the invention. Accordingly, it is to be understood that
the invention is not to be limited by the specific illustrated
embodiment but only by the scope of the appended claims.
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