U.S. patent application number 11/726223 was filed with the patent office on 2007-12-13 for semi-rigid spinal fixation apparatus.
Invention is credited to Kyung-Woo Park.
Application Number | 20070288008 11/726223 |
Document ID | / |
Family ID | 36075050 |
Filed Date | 2007-12-13 |
United States Patent
Application |
20070288008 |
Kind Code |
A1 |
Park; Kyung-Woo |
December 13, 2007 |
Semi-rigid spinal fixation apparatus
Abstract
A semi-rigid spinal apparatus has a first pedicle screw array
and a second pedicle screw array substantially parallel to the
first pedicle screw array. A first rod array is associated with the
first pedicle screw array and a second rod array is associated with
the second pedicle screw array. Each of the first and second
pedicle screw arrays include a plurality of pedicle screws for
joining to vertebrae of a spine. Each pedicle screw includes a head
portion having a plurality of receptacles and a leg portion having
a male thread for implanting into a vertebra. Each of the first and
second rod arrays include a plurality of rod segments and each rod
segment includes a first end coupled to a first receptacle on a
first pedicle screw and a second end coupled to a second receptacle
on a second pedicle screw adjacent to the first pedicle screw.
Inventors: |
Park; Kyung-Woo; (Seoul,
KR) |
Correspondence
Address: |
WILLIAM COLLARD;COLLARD & ROE, P.C.
1077 NORTHERN BOULEVARD
ROSLYN
NY
11576
US
|
Family ID: |
36075050 |
Appl. No.: |
11/726223 |
Filed: |
March 21, 2007 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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11044268 |
Jan 28, 2005 |
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11726223 |
Mar 21, 2007 |
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PCT/KR04/03301 |
Dec 15, 2004 |
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11726223 |
Mar 21, 2007 |
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Current U.S.
Class: |
606/86A ;
606/278 |
Current CPC
Class: |
A61B 17/7005 20130101;
A61B 2017/00867 20130101; A61B 17/7028 20130101; A61B 17/7032
20130101; A61B 17/7004 20130101; A61B 17/7008 20130101; A61B
17/7011 20130101; A61B 2017/0645 20130101; A61B 17/7026 20130101;
A61B 17/7052 20130101; A61B 17/7007 20130101 |
Class at
Publication: |
606/061 |
International
Class: |
A61B 17/58 20060101
A61B017/58 |
Foreign Application Data
Date |
Code |
Application Number |
Sep 22, 2004 |
KR |
10-2004-0076105 |
Sep 22, 2004 |
KR |
10-2004-0076106 |
Nov 26, 2004 |
KR |
10-2004-0097833 |
Nov 26, 2004 |
KR |
10-2004-0097834 |
Claims
1. A semi-rigid spinal fixation apparatus comprising: a) a first
pedicle screw array; b) a second pedicle screw array disposed
substantially parallel to said first pedicle screw array; c) a
first rod array associated with said first pedicle screw array; and
d) a second rod array associated with said second pedicle screw
array; wherein each of said first pedicle screw array and said
second pedicle screw array comprise a plurality of pedicle screws
for joining to vertebrae of a spine, each pedicle screw of said
plurality of pedicle screws comprising a head portion having a
plurality of receptacles and a leg portion having a male thread for
implanting into a vertebra; and wherein each of said first rod
array and said second rod array comprise a plurality of rod
segments, each rod segment of said plurality of rod segments
comprising a first end coupled to a first receptacle of said
plurality of receptacles on a first pedicle screw of said plurality
of pedicle screws and a second end coupled to a second receptacle
of said plurality of receptacles on a second pedicle screw of said
plurality of pedicle screws, said first pedicle screw being
adjacent to said second pedicle screw.
2. The semi-rigid spinal fixation apparatus according to claim 1
further comprising a transverse link extending between a first rod
segment associated with said first rod array and a second rod
segment associated with said second rod array.
3. The semi-rigid spinal fixation apparatus according to claim 1,
wherein each rod segment of said plurality of rod segments
comprises an elastic section.
4. The semi-rigid spinal fixation apparatus according to claim 3,
wherein said elastic section comprises a coil spring shape.
5. The semi-rigid spinal fixation apparatus according to claim 3,
wherein said elastic section comprises a wave shape.
6. The semi-rigid spinal fixation apparatus according to claim 1,
wherein said head portion of said pedicle screw comprises a
reception cavity and wherein said plurality of receptacles
comprises a plurality of rod grooves disposed on a bottom surface
of said reception cavity.
7. The semi-rigid spinal fixation apparatus according to claim 6,
further comprising a) a head cap coupled to said head portion of
said pedicle screw, said head cap comprising a second plurality of
rod grooves; and b) a fastener for securing said head cap to said
head of said pedicle screw; wherein said rod segment is secured
between a rod groove of said plurality of rod grooves in said
reception cavity and a respective rod groove of said second
plurality of rod grooves in said head cap.
8. The semi-rigid spinal fixation apparatus according to claim 6,
wherein said rod segment further comprises a hook shaped portion at
each end and said head portion of said pedicle screw comprises a
fixing recess positioned under a rod groove of said plurality of
rod grooves, wherein said hook shaped portion is fixed in said
fixing recess.
9. The semi-rigid spinal fixation apparatus according to claim 1,
further comprising a head cap coupled to said head portion of said
pedicle screw.
10. The semi-rigid spinal fixation apparatus according to claim 1,
wherein said head portion of said pedicle screw further comprises a
reception portion having a female threaded portion on an inner
surface of said reception portion, said apparatus further
comprising a set screw having a male threaded portion for engaging
said female threaded portion, wherein said set screw secures said
rod segment to said pedicle screw.
11. The semi-rigid spinal fixation apparatus according to claim 1,
wherein said head portion of said pedicle screw comprises a
reception cavity and wherein said plurality of receptacles
comprises two parallel rod grooves disposed on a bottom surface of
said reception cavity and wherein said rod segment comprises a
straight bar placed in line with said head portions of said first
and second pedicle screws, an elastic section, a support bar having
a bending portion extending from an end of the straight bar and
bending around an outer surface of said head portion, and a line
portion extending from said bending portion, said line portion
coupled to a groove of said two parallel rod grooves.
12. The semi-rigid spinal fixation device according to claim 11,
further comprising a set screw inserted into said reception cavity
for securing said rod segment to said pedicle screw.
13. The semi-rigid spinal fixation apparatus according to claim 1,
wherein said plurality of receptacles comprise a plurality of
circular grooves disposed on an outer surface of said head portion
of said pedicle screw and wherein said rod segment comprises a
straight bar placed in line with said head portions of said first
and second pedicle screws, an elastic section and a support ring,
said support ring coupled to a circular groove of said plurality of
circular grooves.
14. The semi-rigid spinal fixation apparatus according to claim 1,
wherein said rod segment has a substantially u-shaped cross
section.
15. A semi-rigid spinal fixation apparatus comprising: a) a first
pedicle screw, a second pedicle screw and a third pedicle screw,
each comprising a head portion having a plurality of receptacles
and a leg portion having a male thread for implanting into a
vertebra; b) a first rod segment comprising a first end coupled to
a first receptacle of said plurality of receptacles associated with
said first pedicle screw and a second end coupled to a first
receptacle of said plurality of receptacles associated with said
second pedicle screw; and c) a second rod segment comprising a
first end coupled to a second receptacle of said plurality of
receptacles associated with said second pedicle screw and a second
end coupled to a first receptacle of said plurality of receptacles
associated with said third pedicle screw.
16. The semi-rigid spinal fixation apparatus according to claim 15
further comprising a transverse link for coupling said first rod
segment to a rod segment extending between two additional pedicle
screws.
17. The semi-rigid spinal fixation apparatus according to claim 15,
wherein said first rod segment and said second rod segment each
comprise a respective elastic section.
18. The semi-rigid spinal fixation apparatus according to claim 17,
wherein said elastic section comprises a coil spring shape.
19. The semi-rigid spinal fixation apparatus according to claim 17,
wherein said elastic section comprises a wave shape.
20. The semi-rigid spinal fixation apparatus according to claim 15,
wherein said head portion of each of said first, second and third
pedicle screw comprises a respective reception cavity and wherein
said plurality of receptacles comprises a plurality of rod grooves
disposed on a bottom surface of said reception cavity.
21. The semi-rigid spinal fixation apparatus according to claim 20,
further comprising a) a head cap coupled to said head portion of a
respective pedicle screw of said first, second and third pedicle
screw, said head cap comprising a second plurality of rod grooves;
and b) a fastener for securing said head cap to said head of said
pedicle screw; wherein a respective rod segment of said first and
second rod segment is secured between a rod groove of said
plurality of rod grooves in said reception cavity and a respective
rod groove of said second plurality of rod grooves in said head
cap.
22. The semi-rigid spinal fixation apparatus according to claim 20,
wherein a rod segment of said first and second rod segment further
comprises a hook shaped portion at each end and said head portion
of a respective pedicle screw of said first, second and third
pedicle screw comprises a fixing recess positioned under a rod
groove of said plurality of rod grooves, wherein said hook shaped
portion is fixed in said fixing recess.
23. The semi-rigid spinal fixation apparatus according to claim 15,
further comprising a head cap coupled to said head portion of a
respective pedicle screw of said first, second and third pedicle
screw.
24. The semi-rigid spinal fixation apparatus according to claim 15,
wherein said head portion of a respective pedicle screw of said
first, second and third pedicle screw further comprises a reception
portion having a female threaded portion on an inner surface of
said reception portion, said apparatus further comprising a set
screw having a male threaded portion for engaging said female
threaded portion, wherein said set screw secures a rod segment of
said first and second rod segment to said respective pedicle
screw.
25. The semi-rigid spinal fixation apparatus according to claim 15,
wherein said head portion of a respective pedicle screw of said
first, second and third pedicle screw comprises a reception cavity
and wherein said plurality of receptacles comprises two parallel
rod grooves disposed on a bottom surface of said reception cavity
and wherein a rod segment of said first and second rod segment
comprises a straight bar placed in line with said head portions of
said first, second and third pedicle screws, an elastic section, a
support bar having a bending portion extending from an end of the
straight bar and bending around an outer surface of said head
portion, and a line portion extending from said bending portion,
said line portion coupled to a groove of said two parallel rod
grooves.
26. The semi-rigid spinal fixation device according to claim 11,
further comprising a set screw inserted into said reception cavity
for securing said rod segment to said pedicle screw.
27. The semi-rigid spinal fixation apparatus according to claim 15,
wherein said plurality of receptacles comprise a plurality of
circular grooves disposed on an outer surface of said head portion
of a respective pedicle screw of said first, second and third
pedicle screw and wherein said a rod segment of said first and
second rod segment comprises a straight bar placed in line with
said head portions of said first, second and third pedicle screws,
an elastic section and a support ring, said support ring coupled to
a circular groove of said plurality of circular grooves.
28. The semi-rigid spinal fixation apparatus according to claim 1,
wherein said first and second rod segment have a substantially
u-shaped cross section.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application is a continuation-in part of U.S.
application Ser. No. 11/044,268 filed on Jan. 28, 2005, which
claims priority under 35 USC .sctn. 119 of Korean Application No.
10-2004-0076105 filed on Sep. 22, 2004; Korean Application No.
10-2004-0076106 filed on Sep. 22, 2004; Korean Application No.
10-2004-0097833 filed on Nov. 26, 2004 and Korean Application No.
10-2004-0097834 filed on Nov. 26, 2004.
[0002] This application is also a continuation-in part of
International Application NO. PCT/KR2004/003301 filed on Dec. 15,
2004 which claims priority from Korean Application No.
10-2004-0076105 filed on Sep. 22, 2004; Korean Application No.
10-2004-0076106 filed on Sep. 22, 2004; Korean Application No.
10-2004-0097833 filed on Nov. 26, 2004 and Korean Application No.
10-2004-0097834 filed on Nov. 26, 2004.
BACKGROUND OF THE INVENTION
[0003] 1. Field of the Invention
[0004] The invention relates to a spinal fixation apparatus which
can correct and immobilize an injured or deformed human spine. More
particularly, the invention relates to a spinal fixation apparatus
for easily carrying out an operation on the spine, by using segment
flexible rods.
[0005] 2. The Prior Art
[0006] Typically, the vertebra includes 24 bones (except for sacral
vertebra) connected to each other through joint segments. Discs are
disposed between the joint segments. This structure allows the
vertebra to maintain posture and absorb shock. The vertebra is also
essential for exercise and protects all internal organs from
external shocks. However, the vertebra of the spine can be injured
or wrenched by external environments, prolonged abnormal posture,
anaplastia and other influences, which may induce serious back pain
by pressing on the nerve system passing through the spine.
[0007] Patients sustaining injuries to the spine may be unable to
participate in many activities of daily life, because the injured
part of the spine is compressed by other adjacent parts of the
spine. This spinal disorder requires surgical intervention to treat
the pain which is induced in nerve roots by the compression and
instability of the intervertebral joints.
[0008] As shown in FIG. 1, a conventional rigid spinal fixation
apparatus includes a plurality of pedicle screws 200 which are
respectively inserted through the pedicle into the injured or
deformed vertebra. Each of the pedicle screws 200 may have a head
201 formed at a top portion thereof. The head 201 has a U-shaped
rod passage 201a and a female thread 201b is formed on an inner
surface thereof. A thread 202 is formed below the head 201 in order
that the pedicle screws 200 can be implanted into the vertebra. A
pair of longitudinal rods 250 are located in both laterals of the
spine and coupled to the pedicle screws 200 for preventing a
movement of the vertebra. A number of set screws 300, each of which
has a male thread and a wrench hole 300a on an upper surface
thereof are inserted into the rod passage 201a of the head 201 of
the pedicle screw 200 for preventing a movement of the rod. A
transverse link 400 is provided for holding the longitudinal rods
250.
[0009] In the conventional rigid spinal fixation apparatus, the
rods and the pedicle screws are described below with reference to
the accompanying drawing.
[0010] As shown in FIG. 2, the thread 202 of the pedicle screws 200
is implanted into the vertebral body 500. The rod 250 is then
inserted into the rod passage 201a. In this situation, the set
screw 300 is joined to the female thread 201b of the rod passage
201a.
[0011] The set screw 300 is also joined to the rod passage 201a by
inserting it into a groove 300a and turning it with a wrench on the
top thereof. As a result, the bottom side of the set screw 300
compresses the top of the rod 250 within the rod passage 201a of
the pedicle screws 200.
[0012] According to this assembly, the rod 250 is tightened up on
the pedicle screw 200 to correct the diseased or injured vertebral
body 500. Each end of the transverse link 400 is coupled to a
respective one of the pair of rods 250 and the transverse link 400
is laid across the rods 250 which are connected to the pedicle
screws 200. When a patient does a wrenched action toward his left
or right side, the transverse link 400 prevents rotation and
migration of the rod 250.
[0013] In the conventional rigid spinal fixation apparatus, the rod
250 functions as a basic element to correct the vertebra.
Therefore, the material and properties of the rod, such as
elasticity, have a large effect on human body, as the rod is
inseparably fused together with the vertebra. The conventional rod
250 may be made from a titanium alloy for medicine and is not
elastic. It is very difficult to keep the line of his lumber normal
since the vertebra segment is fused together with the rod to
correct the vertebra bodies.
[0014] Various post operation problems may arise when using the
conventional rigid spinal fixation apparatus. For example, after
the vertebra is integrally fused together with the rod, the weight
is concentrated upon the upper segment or the lower segment so that
it will cause another vertebra stegnotic or instability of a lumbar
vertebra within a few years after the vertebra fusion.
Additionally, the rod of the conventional rigid spinal fixation
apparatus can be broken and buried in the vertebra when a shock is
inflicted upon the lumbar vertebra. Other complications
attributable to the conventional rigid spinal fixation apparatus
include pseudo-arthrosis, adjacent segmental disease, abnormal load
transmission and abnormal sagittal balance.
[0015] In the conventional rigid spinal fixation apparatus, the rod
is made to have a normal spinal curvature shape without being
related to a specific spinal shape of individual. This causes the
difficulty of standardizing each single product and making various
shapes, thereby increasing the cost of the product. Also, the
conventional rod structure induces a series of bottlenecks in
connecting the pedicle screw to the rod because the rod has a
straight shape wherein individual spinal shapes differ from patient
to patient. Therefore, if the pedicle screws are not fixed
uniformly between the segments, it was very difficult to install
the conventional straight rod on the pedicle screws. This is caused
by the physical properties of the rod.
[0016] In the case of the conventional rigid spinal fixation
apparatus, an operator must adjust a distance and direction of the
pedicle screw based on the location of the rod by making the
pedicle screw slanted. Also, the operator has to adjust an angle of
the pedicle screw's head, using a polyaxial type screw, which can
freely rotate a head around the screw in a range of predetermined
angles and set the rod up thereon. The procedure using the
conventional rigid spinal fixation apparatus requires great
accuracy, because the operator must correctly grasp the location to
install the pedicle screw and then make a hole in vertebra, placing
a burden on the surgeon. Additionally, making the rod based on a
curved shape of patient's vertebra and setting the location of
pedicle screw require a substantial period of time.
[0017] To solve the problems of the conventional rigid spinal
fixation apparatus, various types of the rods has been provided
with elasticity.
[0018] An example of an elastic rod for connecting the pedicle
screws is illustrated in Korean utility model No. 0,338,006. This
rod comprises a rod body 601 and an elastic connection portion 603
formed in the middle of the rod body 601. As shown in FIG. 3, the
elastic rod may be provided in various types, such as a
semicircular ring, a coil spring, a bar type smaller then the
diameter of the rod body, and the like.
[0019] The known elastic rods shown in FIG. 3 provide an elastic
connection portion for the rod in order that the rod body can be
bent. This structure is capable of giving fluidity to the rod in a
predetermined range between the pedicle segments. However, the
known rod structure results in a loss of the basic function of the
spine correction since the elastic connection portion causes large
movement. That is, the rod has to support and connect the spinal
segments. In the above-mentioned structure, the pieces of the rod
body are detachable so that they are freely movable in a given
elastic range. Therefore, a secure connection between the spinal
segments is not achieved.
[0020] A further disadvantage of the known rod structure is that
when the pedicle screws are not aligned in a straight line, it is
difficult to connect the rod to the pedicle screw.
[0021] FIG. 4 shows a perspective view of a conventional transverse
link 400 for preventing the pedicle from a minute movement.
[0022] The conventional transverse link 400 comprises a fixed type
housing 410 and a movable type housing 420 which are respectively
hooked on both ends of the rod 250; a space bar 430 supported on
the rod 250; and a set screw 440 connected with the fixed type
housing 410 and the movable type housing 420 so that the space bar
430 is fixed to the rod 250.
[0023] The conventional fixed type housing 410 and movable type
housing 420 shown in FIG. 4 respectively include half circle hooks
410a and 420a for connection on the rod 250; support holes 410b and
420b inserted into the both ends of the rod 250; and screw holes
410c and 420c into which set screws 440 are inserted.
[0024] The hook 410a of the conventional fixed type housing 410 is
hooked on the rod 250 and then one end of the space bar 430 is
inserted into the support hole 410b. The hook 420a of the
conventional movable type housing 420 is hooked on the rod 250 and
then another end of the space bar 430 is inserted into the support
hole 420b. The set screws 440 are joined to the screw holes 410c
and 420c respectively, for securely tightening the rod 250 under
the space bar 430.
[0025] In the conventional transverse link 400 structure, the inner
diameter of the hook 410a is almost equal to that of the rod 250.
Therefore, if one of the rods 250 is tilted or adjacent rods are
not in parallel, the transverse link 400 cannot comply with such a
declination or unbalance of the rods 250. In the case of
declination or unbalance of the rods 250, the support holes 410a
and 420a of the conventional fixed type housing 410 and
conventional movable type housing 420 are also unbalanced and thus
the space bar 430 cannot be inserted into the support holes 410b
and 420b. If stress is put on the space bar 430 for fixation on the
support holes 410b and 420b, the position of the conventional
movable type housing 420 may be wrenched and distorted so that the
rod 250 may be separated from the hook 420a of the conventional
movable type housing 420. In this case, even if the set screw 440
is joined to the screw hole 430, it is impossible to securely
support the space bar 430 upon the rod 250. This problem in the
conventional transverse link 400 increases the time required for
surgery. The conventional transverse link 400 may be omitted in
cases where it is difficult to assemble, however, this omission may
cause a defect in the surgery.
[0026] The known rigid spinal fixation systems provide fixation
which allows little or no motion whatsoever. In operation of the
known rigid spinal fixation systems, a single rod is used to adjust
each section. This causes complications in that the pedicle screws
inserted into each section are not always aligned, thus leaving no
option except bending the rod.
[0027] Accordingly, a need exists for a semi-rigid spinal fixation
apparatus which can provide dynamic fixation allowing for movement
or motion. A need further exists for a semi-rigid spinal fixation
apparatus employing a segmental connection method which allows for
the connecting of individual rod segments to each section of the
apparatus, thereby eliminating the need to bend the rod in the
event that the pedicle screws are not aligned.
SUMMARY OF THE INVENTION
[0028] To solve the problems of the known spinal fixation devices,
a primary object of an embodiment of the present invention is to
provide a spinal fixation apparatus which can easily and simply
achieve a connection between pedicle screws and a rod during
surgery, even if the pedicle screws are slightly out of
alignment.
[0029] Another object of an embodiment of the present invention is
to provide a semi-rigid spinal fixation apparatus which has enough
strength to correct the spine during restoration from an elastic
force so that the spinal fixation apparatus gives flexible behavior
to correct vertebral segments.
[0030] A further object of an embodiment of the invention is to
provide a semi-rigid spinal fixation apparatus which provides for
segmented connection of pedicle screws and eliminates the need for
bending of a rod.
[0031] Further, another object of an embodiment of the present
invention is to provide a staple type rod which is made from a
shape memory alloy. The staple type rod of the present invention
can easily and simply perform a vertebra correction operation and
reduce the number of parts being implanted directly into selected
vertebra without a pedicle screw.
[0032] In one aspect, a semi-rigid spinal apparatus according to an
embodiment of the invention includes a first pedicle screw array
and a second pedicle screw array disposed substantially parallel to
the first pedicle screw array. A first rod array is associated with
the first pedicle screw array and a second rod array is associated
with the second pedicle screw array.
[0033] Each of the first pedicle screw array and the second pedicle
screw array include a plurality of pedicle screws for joining to
vertebrae of a spine. Each pedicle screw includes a head portion
having a plurality of receptacles and a leg portion having a male
thread for implanting into a vertebra.
[0034] Each of the first rod array and second rod array include a
plurality of rod segments and each rod segment includes a first end
coupled to a first receptacle on a first pedicle screw and a second
end coupled to a second receptacle on a second pedicle screw
adjacent to the first pedicle screw.
[0035] In another aspect, a semi-rigid spinal apparatus according
to an embodiment of the invention includes a first pedicle screw, a
second pedicle screw and a third pedicle screw. Each of the first,
second and third pedicle screws include a head portion having a
plurality of receptacles and a leg portion having a male thread for
implanting into a vertebra.
[0036] A first rod segment includes a first end coupled to a first
receptacle associated with the first pedicle screw and a second end
coupled to a first receptacle associated with the second pedicle
screw. A second rod segment includes a first end coupled to a
second receptacle associated with the second pedicle screw and a
second end coupled to a first receptacle associated with the third
pedicle screw.
[0037] In accordance with another aspect of an embodiment of the
present invention, a spinal fixation apparatus is provided
comprising: a plurality of pedicle screws, each of which has a head
formed at a top portion thereof and a thread formed below the head
to be implanted into a pedicle of a vertebra. The head has a
reception cavity and at least one rod groove on a bottom surface of
the reception cavity. A pair of rods is connected to the pedicle
screws for preventing a movement of the vertebra. The rods have an
elasticity section therein and are mounted on the rod groove in the
reception cavity. At least one transverse link having an elasticity
section in a straight member and hooks extending from both ends of
the straight member is provided for rigidly holding the pair of
rods. A plurality of set screws, each of which is rigidly inserted
into the reception cavity of the head, prevent movement of the
rods. The rods and/or the transverse link may be made from a shape
memory alloy which can be deformed at a predetermined
temperature.
[0038] In accordance with another aspect of an embodiment of the
present invention, a spinal fixation apparatus is provided
comprising a plurality of pedicle screws, each of which has a head
formed at a top portion thereof and a thread formed below the head
to be implanted into a pedicle of a vertebra. The head has a first
rod groove formed in a bottom surface of the head. A plurality of
head caps is provided for covering the head of the pedicle screw.
The head caps have a second rod groove formed on an inner surface
thereof. A pair of rods surrounded by the first rod groove of the
head and the second rod groove of the head cap prevent movement of
the vertebra. The rods have an elasticity section therein. At least
one transverse link which has an elasticity section in a straight
member and hooks extended from both ends of the straight member is
provided for rigidly holding the pair of rods. A plurality of
fixing means, each of which tightens the head cap to the head of
the pedicle screw, are inserted into the reception cavity of the
head of the pedicle screws for preventing movement of the rod. The
rods and/or the transverse links may be made from a shape memory
alloy which can be deformed at a predetermined temperature.
[0039] In accordance with another aspect of an embodiment of the
present invention, a spinal fixation apparatus is provided
comprising a plurality of pedicle screws, each of which has a head
formed at a top portion thereof and a thread formed below the head
to be implanted into a pedicle of a vertebra. The head has a
reception cavity and two parallel rod grooves in a bottom surface
of the reception cavity. A pair of rods is connected to the pedicle
screws for preventing movement of the vertebra. The rods may be
made of shape memory alloy which can be transformed at a designated
temperature. The rods include a straight bar placed in line with a
center of the heads, an elastic section formed in the straight bar,
support bars having bending portions extending from both ends of
the straight bar and bent along an outer surface of the head, and
line portions extended from both ends of the bending portions and
put in the rod grooves. A plurality of set members, each of which
is inserted into the reception cavity of the head of the pedicle
screws, prevent movement of the rods.
[0040] In accordance with still another aspect of an embodiment of
the present invention, a spinal fixation apparatus is provided
comprising a plurality of pedicle screws, each of which has a head
formed at a top portion thereof, and a thread formed below the head
to be implanted into a pedicle of a vertebra. The head has at least
one circular groove on an outer surface thereof. A pair of rods is
connected to the pedicle screws for preventing movement of the
vertebra. Each of the rods has a straight bar placed in line with a
center line of the heads, an elastic section formed in the straight
bar, and support rings wound on the circular grooves of the heads.
The rods may be made from a shape memory alloy which can be
deformed at a predetermined temperature.
[0041] In accordance with still another aspect of an embodiment of
the present invention, a spinal fixation apparatus is provided
comprising a plurality of pedicle screws, each of which has a head
formed at a top portion thereof, and a thread formed below the head
to be implanted into a pedicle of a vertebra. The head has a
horizontal opening passing through a head body and a perpendicular
thread hole to receive a fixing means. A pair of rods is connected
to the pedicle screws for preventing movement of the vertebra. The
rods have a straight bar and hooks extending from both ends of the
straight bar which are bent to be inserted into the horizontal
openings. The rods may be made from a shape memory alloy which can
be deformed at a predetermined temperature. A plurality of fixing
means are coupled to the perpendicular thread hole of the head for
preventing movement of the rod.
[0042] In accordance with still another aspect of an embodiment of
the present invention, a spinal fixation apparatus is provided
comprising a plurality of pedicle screws, each of which has a head
formed at a top portion thereof and a thread formed below the head
to be implanted into a pedicle of a vertebra. The head has a
reception cavity and two parallel rod grooves in a bottom surface
of the reception cavity. A pair of rods is connected to the pedicle
screws for preventing movement of the vertebra. Each of the rods
has a "U" shape. The rods may be made from a shape memory alloy
which can be deformed at a predetermined temperature. A plurality
of set members, each of which is inserted into the reception cavity
of the head of the pedicle screws, prevent a movement of the
rod.
[0043] In accordance with still another aspect of an embodiment of
the present invention, a spinal fixation apparatus is provided
comprising at least one pedicle screw which has a head at a top
portion thereof and a thread formed below the head to be implanted
into a pedicle of a vertebra. The head has a reception cavity and
two parallel sockets formed in a bottom of the reception cavity. A
pair of staple rods is connected to the pedicle screws for
preventing movement of the vertebra. One side of each of the rods
is directly implanted into a pedicle of the vertebra and the other
side is inserted into one of the sockets. At least one set member
is inserted into the reception cavity of the head of the pedicle
screws for preventing movement of the rod.
[0044] In accordance with still another aspect of an embodiment of
the present invention, a spinal fixation apparatus is provided
comprising at least one staple rod having a bridge member for
providing a space between a selected vertebra and an adjacent
vertebra. An elastic section and a spike member to be implanted
into the pedicle of a vertebra are formed in the bridge member. The
spike member extends downwardly from both ends of the bridge
member. The rod may be made from a shape memory alloy which can be
deformed at a predetermined temperature.
[0045] In accordance with still another aspect of an embodiment of
the present invention, a spinal fixation apparatus is provided
comprising a plurality of pedicle screws having a head part and a
pair of rods for connecting the pedicle screws. The rods are in a
first structure at a first temperature range and are in a second
structure at a second temperature range, wherein the second
structure is a memorized shape of a shape memory alloy. The rods
provide a handling margin in the first structure so that the rods
of the memorized shape are tighter than those of the first
structure. The head part has a fixating means for securely fixing
the rod. The end parts of the rod are joined to the fixating
means.
[0046] In accordance with still another aspect of an embodiment of
the present invention, a spinal fixation apparatus is provided
comprising first and second pedicle screw arrays perpendicularly
arranged, substantially being in parallel to each other. Each of
the first and second pedicle screw arrays includes a plurality of
pedicle screws joined to vertebras of human spine. Each pedicle
screw includes a head having a plurality of reception means and a
male thread formed on a leg part to be implanted into the
vertebras. First and second rod arrays are provided, respectively
connected the first and second pedicle screw arrays. Each of the
first and second rod arrays includes a plurality of segment rods.
An end of each the segment rods is safely secured to one of the
plurality of reception means. The segment rods may be a shape
memory alloy.
[0047] An advantage of a semi-rigid spinal fixation apparatus
according to an embodiment of the invention is that a dynamic
apparatus is provided which allows motion. Such motion results from
a configuration of the rod which may include an elastic section
having a spiral or spring shape.
[0048] Another advantage of a semi-rigid spinal fixation apparatus
according to an embodiment of the invention is that the apparatus
may employ a segmental connection method wherein individual rod
segments are coupled to each pair of adjacent pedicle screws. Such
a segmental connection method eliminates the need for bending of
the rod. Additionally, an arrangement according to an embodiment of
the invention also has the advantage of simplifying a subsequent
operation on damaged adjacent spinal segments as it is unnecessary
to tamper with or disturb prior segments that have been operated on
and only the damaged adjacent segments are the subject of the
subsequent operation.
[0049] A further advantage of a semi-rigid spinal fixation
apparatus according to an embodiment of the invention is that the
apparatus is particularly advantageous for operations requiring
fusion.
[0050] A further advantage of a semi-rigid spinal fixation
apparatus according to an embodiment of the invention is that the
apparatus may be adapted in term of stiffness or flexibility to
achieve the goals of different types of spinal operations by
choosing a suitable material, rod diameter and rod elastic section
configuration.
BRIEF DESCRIPTION OF THE DRAWINGS
[0051] Other objects and benefits of the present invention will
become apparent upon consideration of the following written
description taken in conjunction with the following figures:
[0052] FIG. 1 is a perspective view illustrating a conventional
spinal fixation apparatus;
[0053] FIG. 2 is a perspective view illustrating a conventional
spinal fixation apparatus applied to the lumbar spine;
[0054] FIG. 3 is a plan view illustrating various forms of
conventional rods;
[0055] FIG. 4 is a perspective view illustrating a conventional
transverse link applied to the rods;
[0056] FIG. 5 is a perspective view illustrating a spinal fixation
apparatus according to an embodiment of the present invention;
[0057] FIG. 6 is a perspective view illustrating an assembly of the
spinal fixation apparatus shown in FIG. 5;
[0058] FIG. 7 is a cross-section view taken along A-A line shown in
FIG. 6;
[0059] FIG. 8 is a plan view illustrating another form of a rod
according to an embodiment of the present invention;
[0060] FIG. 9 is a sectional view illustrating a pedicle screw
according to an embodiment of the present invention;
[0061] FIG. 10 is a plan view illustrating a serial connection of
the rods and the pedicle screws shown in FIG. 9;
[0062] FIG. 11 is a perspective view illustrating a transverse link
applied to the rods according to an embodiment of the present
invention;
[0063] FIG. 12 is a front view illustrating a connection between
the transverse link and rods;
[0064] FIG. 13a is a perspective view illustrating another form of
a rod;
[0065] FIG. 13b is a plan view illustrating another form of a
rod;
[0066] FIG. 14 is a perspective view illustrating a connection
between the transverse links and a head of the pedicle screw;
[0067] FIG. 15 is a front view illustrating a spinal fixation
apparatus according to another embodiment of the present
invention;
[0068] FIG. 16 is a perspective view illustrating a spinal fixation
apparatus according to another embodiment of the present
invention;
[0069] FIG. 17 is a plan view illustrating a serial connection of
the rods to a head of a pedicle screw shown in FIG. 16;
[0070] FIG. 18 is a perspective view illustrating a spinal fixation
apparatus according to another embodiment of the present
invention;
[0071] FIG. 19 is a perspective view illustrating a serial
connection of the rods to a head of a pedicle screw shown in FIG.
18;
[0072] FIG. 20 is a plan view illustrating an assembly of spinal
fixation apparatus shown in FIG. 18;
[0073] FIG. 21 is a perspective view illustrating a spinal fixation
apparatus according to another embodiment of the present
invention;
[0074] FIGS. 22a and 22b are perspective views illustrating a
spinal fixation apparatus according to another embodiment of the
present invention;
[0075] FIG. 23 is a perspective view illustrating a spinal fixation
apparatus according to another embodiment of the present
invention;
[0076] FIG. 24 is a perspective view illustrating a staple rod
according to an embodiment of the present invention;
[0077] FIG. 25 is plan view illustrating a pedicle screw in the
seventh embodiment of the present invention;
[0078] FIG. 26 is a perspective view illustrating a serial
connection of the stapling rods to a head of the pedicle screw
shown in FIG. 23;
[0079] FIG. 27 is a perspective view illustrating a spinal fixation
apparatus according to another embodiment of the present invention;
and
[0080] FIG. 28 is a perspective view illustrating another form of
the staple rod.
DETAILED DESCRIPTION OF THE DRAWINGS
[0081] Hereinafter, the present invention will be described in
detail referring to the accompanying drawings. A spinal fixation
apparatus according to embodiments of the present invention can
easily correct injured spines by using rods and/or transverse
links. The rods may be made from a titanium alloy, a shape memory
alloy or any other suitable material. The transverse links are
preferably made from Nitinol alloy (Ni--Ti alloy) which has
superelastic characteristics.
[0082] Various embodiments of the invention will be described in
detail referring to FIGS. 5 to 14.
[0083] According to one embodiment of present invention, a spinal
fixation apparatus includes a plurality of pedicle screws 1
implanted into the patient's vertebra; a pair of rods 2 located in
both laterals of the spine and connected to the pedicle screws for
preventing a movement of the vertebra; and a number of transverse
links 3 for providing space between the rods.
[0084] Referring now to FIGS. 5 to 7, the pedicle screw 1 comprises
a head 11 formed at a top portion thereof and a thread 13 formed
below the head to be implanted into the vertebra. The head 1 has a
reception cavity 11a to receive the rod 2 and at least one rod
groove 12 at the bottom of the reception cavity 11a. A diameter of
the rod groove 12 corresponds to that of the rod 2.
[0085] The rod 2 has a rod body 15 which is bent and then has a
hook shape at both ends thereof and the rod 2 has an elasticity or
elastic section 16 formed in the middle of the rod body 15 to
generate an elastic force corresponding to a shock which is
inflicted on the patient's vertebra.
[0086] The elastic section 16 may be made of a coil spring. The
coil spring may be equal to the rod body 15 in diameter. Another
form of the elastic section 16 is shown in a wave shape as shown in
FIG. 8. The flexibility and stiffness of a rod according to an
embodiment of the invention may be adjusted by adjusting the
diameter of the rod and/or adjusting the configuration of the
elastic section 16 of a rod. For example, the distance between
coils of a coil shaped elastic section may be increase or reduced
to adjust the flexibility/stiffness of the rod 2.
[0087] The diameter of the rod is approximately in a range of 2 to
7 mm and it can be adjusted on a basis of unit diameter of 0.5 mm.
When the stiffness of a 6 mm titanium rigid straight rod is said to
be 100, a 4 mm titanium rigid straight rod would have a stiffness
of 60. At this level, the 4 mm rod would be characterized as
semi-rigid. Due to an elastic section included in rod segments
according to embodiments of the invention, rod segments according
to embodiments of the invention have even less stiffness then
straight rods and may be characterized as flexible.
[0088] There is an inverse relationship between flexibility and
stiffness, as one increase the other decreases. In the case of
known rigid spinal fixation systems having 6 mm titanium rods, the
system has only stiffness making motion of the effected spinal
segments impossible. In the case of a spinal fixation system
according to an embodiment of the invention, secured fixation,
suitable body motion and durability can be achieved by varying the
degree of flexibility. In particular, the desired characteristics
can be met by selecting the proper material, rod diameter and
elastic section configuration. For example, a study indicated that
when a rod diameter was increased by 0.25 mm, the rod stiffness
rose by 14.5-17.17% and when a direction of the rod spring or
elastic section moved from back to front, the stiffness rose
17.34%.
[0089] The elastic section 16 serves as a buffer between spinal
segments when the pedicle screw 1 is fused together with the spine.
That is, when a patient bends or wrenches his waist or a shock is
inflicted on his waist, the elasticity section 16 can alleviate
stimuli which are caused by patients' activities or the external
shock.
[0090] A set screw 17 is inserted into the reception cavity 11a of
the head 11 of the pedicle screws 1 for preventing a movement of
the rod 2. The set screw 17 has an outer thread 17a for securely
tightening the rod 2 and a recess 17b having a hexagonal
cross-section view on the upper portion thereof so that the set
screw 17 is inserted into the reception cavity 11a of the head 11.
The length of the set screw 17 should be short enough not to
protrude from the upper surface of the reception cavity 11a of the
head 11.
[0091] The reception cavity 11a of the head 11 also has an inner
thread 11b to be joined to the outer thread 17a of the set screw
17.
[0092] The head 11 of the pedicle screw 1 has a rod fixing recess
14 for tightening an end of the rod 2. The rod 2 is inserted into
the reception cavity 11a and is put into the rod groove 12 as the
end of the rod is tightly inserted into the rod fixing recess
14.
[0093] The rod fixing recess 14 and the rod 2 may have the same
diameter or the diameter of the rod fixing recess 14 may be
slightly larger than that of the rod 2.
[0094] A head cap 18 can be adopted on the upper portion of the
head 11 to eliminate the change from a misaligned fixation of the
set screw 17. Since the head cap 18 provides an additional support
to improve the rod holding power, this can be used as an additional
rod such as a fastening element. The head cap 18 is additionally
set as needed, and may not be essential.
[0095] The head 11 of the pedicle screw 1 may include two rod
grooves 12 and 12' and two rod fixing recess 14, 14', as shown in
FIG. 9. According to this structure, it is able to serially set the
rods 2 without using an additional connector by inserting the rods
2 and 2' into the rod grooves 12 and 12' alternately, as shown in
FIG. 10.
[0096] The pedicle screws 1 of a semi-rigid spinal fixation
apparatus according to an embodiment of the invention may be
arranged in a first pedicle screw array and a second pedicle screw
array disposed substantially parallel to the first pedicle screw
array. The rods may be arranged in a first rod array associated
with the first pedicle screw array and a second rod array
associated with the second pedicle screw array.
[0097] Each of the first and second pedicle screw array includes a
plurality of pedicle screws 1 for joining to vertebrae of a spine.
Each pedicle screw 1 has a head portion 11 having a plurality of
receptacles and a leg portion 13 having a male thread for
implanting into a vertebra.
[0098] As shown for example in FIGS. 10, 19 and 22b, each of the
first rod array and second rod array comprise a plurality of rod
segments, each rod segment of said plurality of rod segments
comprising a first end coupled to a first receptacle of said
plurality of receptacles on a first pedicle screw of said plurality
of pedicle screws and a second end coupled to a second receptacle
of said plurality of receptacles on a second pedicle screw of said
plurality of pedicle screws, said first pedicle screw being
adjacent to said second pedicle screw.
[0099] The plurality of receptacles in the head of a pedicle screw
according to various embodiments of the invention may be in the
form of rod grooves 12, 12' (FIG. 9), parallel rod grooves 42,
42'(FIG. 16), circular grooves 61a, 61a' (FIG. 18) or any other
structure suitable for coupling to an end of a rod segment.
[0100] The pedicle screws in a semi-rigid spinal fixation apparatus
according to an embodiment of the invention may include a first
pedicle screw, a second pedicle screw and a third pedicle screw, as
shown, for example in FIGS. 10, 17, 19 and 22b. Each pedicle screw
included a head portion having a plurality of receptacles and a leg
portion having a male thread for implanting into a vertebra.
[0101] As shown, for example in FIGS. 10, 17, 19 and 22b a first
rod segment has a first end coupled to a first receptacle of
associated with the first pedicle screw and a second end coupled to
a first receptacle associated with the second (middle) pedicle
screw. A second rod segment has a first end coupled to a second
receptacle associated with the second pedicle screw and a second
end coupled to a first receptacle associated with the third pedicle
screw.
[0102] The rod or rod segments according to various embodiment of
the invention can be formed in a straight bar shape or a right
angle bar shape which is perpendicular to both ends of the rod
body. In such a modified rod, the structure of the pedicle screw 1
may be formed with a single rod groove without a rod fixing recess
14. Additionally, it may be employed in different structures of the
pedicle screw corresponding to the modified rod. Furthermore, the
modified rod 2 is securely fixed by the set screw 17 within the
reception cavity 11a of the head 11.
[0103] A transverse link 3 will be described in detail referring to
FIGS. 11 and 12. The transverse link may extend between a first rod
segment associated with the first rod array and a second rod
segment associated with the second rod array.
[0104] The transverse link 3 may include one straight member 31 and
two hooks 32 which are respectively extended and bent from both
ends of the straight member 31. The transverse link 3 may be formed
as a rectangular plate. The length of the transverse link 3 is
approximately in a range of 20 to 80 mm and it can be adjusted on a
basis of unit length of 2 mm. As shown in FIG. 12, the transverse
link 3 keeps a space between the rods 2 and 2' by grasping the rods
2 and 2' through the hooks 32. Here, the transverse link 3 of a
plate shape has strength to maintain the space between the rods 2
and 2' even if an external force is applied to the rods 2 and 2'
and the rods 2 and 2' are then wrenched.
[0105] FIG. 13a and FIG. 13b are views illustrating transverse
links which are different from that of FIG. 11. That is, an elastic
or elasticity section 33 is formed in the middle of a straight
member 31. The elasticity section 33 has a coil spring as shown in
FIG. 13a or a wave shape as shown in FIG. 13b. The elasticity
section 33 of the transverse link 3 absorbs a load which is applied
to the rod 2.
[0106] FIG. 14 illustrates an S-shaped transverse link 3 which is
different from that of FIG. 11. The S-shaped transverse link 3
includes one bending member 36 and two hooks 32 which are
horizontally extended and bent from both ends of the bending member
36 for holding the head 11 of the pedicle screw 1. A slit 25 is
provided on the circumference of the head 11 of the pedicle screw 1
in order to insert the hooks 32 of the S-shaped transverse link 3
into the head 11.
[0107] The rods 2 and 2' may be made from a titanium material, from
a shape memory alloy causing deformation at a specific temperature,
or from any suitable material. The transverse links are preferably,
but not necessarily, made from a shape memory alloy. For example
the rods 2 and 2' and/or the transverse links 3 may have a
temperature characteristic that they are in a martensite phase at a
temperature of +10 degree C. and below and in an austenite phase at
a temperature of more than +35 degree C. to return back to a
memorized original shape. In particular, the deformed shape is kept
unchanged up to +26 degree C. and the memorized shape is gradually
restored by a heat treatment up to +35 degree C.
[0108] In an embodiment of the invention, the rods 2 and 2' and/or
the transverse link 3 are obtained by performing a heat treatment
at a temperature of 650 degree C. to 750 degree C. for one hour or
so, after forming the hooks and elastic section at both ends and
the middle section of the shape memory material, respectively.
Thus, the rods 2 and 2' and the transverse link 3 can have a
deforming characteristic at a specific temperature.
[0109] An installation procedures for an embodiment of the present
invention is described in detail as follows:
[0110] The pedicle screws 1 are implanted into a selected pedicle
of the vertebras in a predetermined angle and depth. At this time,
that is not considered configuration of screws that are not well
aligned in general. The elastic section 16 of the rod 2 is
lengthened by deforming the rod 2 at a temperature of +10 degree C.
and below so that the rod 2 is easily set into the reception cavity
11a of the head 11 of the pedicle screw 1, before the rod 2 is
inserted into the reception cavity 11a of head 11 for coupling the
rod 2 to the plurality of the screws 1. Then, the end of the rod 2
having a hook shape is inserted into the rod fixing recess 14,
while a deformed straight member (the rod body 15) of the rod 2 is
inserted to the rod groove 12 which is formed in the bottom of the
reception cavity 11a of head 11. The outer thread 17a of the set
screw 17 is downwardly joined to the reception cavity 11a of the
head 11 so that the set screw 17 is tightly fixed to the inner
thread 11b of the reception cavity 11a using a wrench tool. The rod
2 is pressed by the set screw 17 and the rod 2 is securely and
rigidly fixed to the pedicle screw 1.
[0111] After the installation of the rods 2, a heat treatment is
applied to the rod 2 at a temperature of more than +35 degree C.
using a surgical heating source. Thus, the lengthened elastic
section 16 of the rod 2 is shrunk and returns back to the memorized
original shape in the transforming austenite phase. At this time,
the end of the hook-shaped rod is rigidly fixed to the rod fixing
recess 14 of the head 11 while the rode 2 is returning back to the
memorized original shape. Thus, both ends of the rod 2 are fixed to
the rod fixing recess 14 of the head 11 without any separation.
[0112] According to the embodiment described above, although the
pedicle screws are not well aligned with others, the rods can be
easily and simply connected to the pedicle screw 1 because the rod
2 can be freely bent toward the pedicle screw 1. In addition, the
rod 2 provides for movement of the spinal segments through the
superelastic action of the elastic section 16 when the patients
bends or wrenches his back, after the spinal fusion.
[0113] In the installation procedure for the rods 2, when the rods
2 and 2' are respectively coupled to the rod grooves 12, the
pedicle screw 1 having two rod grooves 12 and 12 may be used. That
is, the rods 2 and 2' are respectively and alternately set to the
rod grooves 12 and 12' positioned in the reception cavity 11a, as
shown in FIG. 10. When a pedicle screw 1 having two rod grooves 12
and 12' is used, it is not necessary to use an additional connector
for a serial connection.
[0114] Next, an installation procedure of the transverse link 3
according to an embodiment of the invention will be described in
detail.
[0115] After coupling the rods 2 and 2' to the pedicle screws 1,
the transverse link 3 is hung on a pair of the rods 2 to provide a
space between the two rods 2. The installing work of the transverse
link 3 is taken in the same manner as it done in the
above-mentioned rod installation procedure. That is, it lengthens a
body 31 or widens a space of the hooks 32 thereof, by deforming the
transverse link 3 at a temperature of +10 degree C. and below. The
deformed hook 32 of the transverse link 3 is inserted into the
outer surface of the rod 2. In the case of an S-shaped transverse
link, it is inserted into a slit 25 of the head 11. After the
installation of the transverse link 3, it returns back to the
memorized original shape, being transformed to the austenite phase
through the heat treatment at a temperature of more than +35 degree
C. so that the transverse link 3 is rigidly fixed on the rod and,
in the case of an S-shaped transverse link 3, it is fixed on the
slit 25 of the pedicle screw 1.
[0116] Thus, in the case of the above-mentioned structure of the
transverse link 3, it easily holds the rod 2 even if a space
between the rods 2 and 2' is not in parallel.
[0117] Another embodiment of the present invention will be
described in detail referring to FIG. 15, wherein the same
reference numerals denote the same elements as illustrated in the
previously described embodiments of the present invention.
[0118] In this embodiment, the head 11 of the pedicle screw 1 is
formed with receptacles comprising a pair of first rod grooves 21
and 21' to locate the rod 2 on an upper portion thereof. Also, a
pair of rod inserting recesses 22 and 22' are respectively formed
below the rod grooves 21 and 21' and the rod inserting recesses 22
and 22' are positioned in the same axis of the rod grooves 21 and
21', respectively. A female thread 23 is formed on an inner surface
of the head 11 at a predetermined depth.
[0119] A head cap 20 is provided on the upper portion of the head
11 and the head cap 20 has a pair of second rod grooves 24 and 24'
corresponding the first rod grooves 21 and 21'. A fixing screw 25
is joined to the female thread 23 passing through the head cap 20
so that the head 11 is strongly fixed to the head cap 20.
[0120] A diameter of the first rod grooves 21 and 21' and the
second rod grooves 24 and 24' may correspond to that of the rods 2
and 2'. The rod inserting grooves 22, 22' may have the same or
slightly large diameter than that of the rod 2.
[0121] If only one of the first rod grooves 21 and 21' is provided,
two female threads may be positioned at both sides of the first rod
groove. If two rod grooves are provided, one female thread may be
positioned in the middle of the first rod grooves 21 and 21'. In
this drawing, a pair of the first rod grooves 21 and 21' is shown.
These two grooves are required to serially and alternately set the
two rods 2 and 2' on the first rod grooves 21 and 21'.
[0122] Additional embodiments of the present invention will be
described in detail referring to FIGS. 16 to 28.
[0123] The rod segments shown in these embodiments may be formed
from a titanium material or any suitable material. Alternatively, a
rod, a staple rod and a middle connection rod in these embodiments
may comprise a shape memory alloy which is in a martensite phase at
a temperature of +10 degree C. and below and in an austenite phase
at a temperature of more than +35 degree C. to return back to the
memorized original shape. The shape memory alloy undergoes a
preliminary deformation at a temperature of +10 degree C. and
below. A deformed shape is kept unchanged up to temperature +26
degree C. A shape restoration is occurs under the heating up to +35
degree C.
[0124] An embodiment of the present invention will be described in
detail referring to FIGS. 16 and 17.
[0125] A plurality of pedicle screws 40 according to this
embodiment may include a head formed at a top portion thereof,
wherein the head has a reception cavity 41a and two parallel rod
grooves 42 and 42' in bottom surface of the reception cavity 41a;
and a thread 43 formed below the head to be implanted into a
pedicle of the vertebra.
[0126] Two parallel rod grooves 42 and 42' in the reception cavity
41a contribute to a connection of the rod segments 50 and the
pedicle screws 40 without an additional connector. Here, the rod
grooves 42, 42' may have a diameter equivalent to the rod segment
50.
[0127] A set screw 44 is inserted into the reception cavity 41a of
the head 41 of the pedicle screws 40 for preventing a movement of
the rod segment 50. In order to securely tighten the rod segment
50, the set screw 44 has an outer thread 44a and a recess 44b which
has a hexagonal cross-section view in the reception cavity 41a of
the head 41. The length of the set screw 44 should be short enough
not to protrude from the upper surface of the reception cavity 41a
of the head 41. The reception cavity 41a of the head 41 has an
inner thread 41b to be joined to the outer thread 44a of the set
screw 44.
[0128] A head cap 45 can be coupled to the upper portion of the
head 41 to eliminate the change from a misaligned fixation of the
set screw 44. The head cap 45 may serve as an additional supporter
to improve the rod holding power using an additional rod-fastening
element.
[0129] A pair of rods or rod segments 50 according to this
embodiment may comprise a straight bar 51 placed at the center line
of the heads; an elastic section 52 formed in the middle of the
straight bar 51 to generate an elastic force for absorbing a shock
which is inflicted on the patient's vertebra; and a support bar 53
extended from both ends of the straight bar 51 to be put in one of
the rod grooves 42 and 42'.
[0130] The diameter of the rod may be approximately in a range of 2
to 7 mm and can be adjusted on a basis of unit diameter of 0.5
mm.
[0131] The elastic section 52 is similar to a coil spring. The coil
spring may be equal to the straight bar 51 in diameter. The elastic
section 52 can also have a wave shape as another form.
[0132] The support bar 53 may have a line portion 53a, which can be
coupled to one of the rod grooves 42a and 42', and a bending
portion 53b which extends from both ends of the straight bar 51 and
curves along the outer surface of the head 41.
[0133] The straight bar 51 of the rod segment 50 is positioned on
the central axis of the head 41 by the shape of the support bar
53.
[0134] One of the two support bars 53 is opposite to the other in
the same head 41; however, the two support bars 53 can also be in a
reverse phase to each other (not shown). That is, rod segment 50
can be serially and alternately connected to the pedicle screw 40
with the support bar 53 of which the bending portions 53b are
reversibly positioned and are curved along the outer surface of the
heads 41.
[0135] Referring to FIG. 17, the support bars 53 at both sides of
the rod segment 50 are respectively put into the rod grooves 42 and
42'. Also, the set screws 44 are coupled to the inner threaded 41b
of the reception cavity 41a of the head 41, being rigidly fixed to
the rod 50 segment.
[0136] Another embodiment of the present invention will be
described in detail referring to FIGS. 18 to 20. Referring now to
FIG. 18, a plurality of pedicle screws 60 and a rod 70 are
shown.
[0137] The pedicle screws 60 include a head 61 formed at the top
portion thereof and a thread 62 formed below the head 61. The head
61a plurality of receptacle in the form of first and second
circular grooves 61a and 61a' formed in an outer surface
thereof.
[0138] Rod segment 70 includes two straight bars 71 and 71' placed
at the center line of the head 61 of the pedicle screw 60, an
elastic section 72 formed in a type of wave between the two
straight bars 71 and 71', and support rings 73 and 73' respectively
extended from both ends of the straight bars 71 and 71' to be
inserted into one of the first and second circular grooves 61a,
61a'.
[0139] The support rings 73 and 73' of the rod segment 70 are may
be in reverse phase to each other; however, they may be opposite to
each other in the same head 61, even if it is not shown in the
drawings.
[0140] Referring now to FIGS. 19 and 20, the rod segments 70 are
serially and alternately connected to the plurality of circular
grooves 61a and 61a' of the heads 61 of the pedicle screws 60,
using the above support rings 73 and 73'.
[0141] A further embodiment of the present invention will be
described in detail referring to FIG. 21.
[0142] Referring now to FIG. 21, this embodiment comprises a
plurality of pedicle screws 80 having a head 81, which is formed at
the top portion thereof and has a cylindrical type block, and a
thread 82 formed below the head 81. The head 81 has an opening 81a
horizontally passing through the cylindrical type block to receive
both ends of a rod 90 and a thread hole 81b which is upwardly
formed and is perpendicular to the opening 81a. The thread hole 81b
of the head 81 is joined to a bolt 83 in order to tighten the rod
90.
[0143] The rod 90 has a straight bar 91 and hooks 92 and 92' which
are roundly extended from both ends of the straight bar 91 to be
inserted to the opening 81a. The straight bar 91 can be provided
with an elastic section in the middle of the rod 90.
[0144] Hereinafter, the installation procedure of the rod 90 will
be described in detail.
[0145] In this embodiment, when the rod 90 is coupled to the
pedicle screw 80, the roundly curved hooks 92 of the rod 90 are
deformed to a straight bar shape at a temperature +10 degree C. and
below. On the other hand, the straight bar shaped hooks 92 of the
rod 90 are inserted to the opening 81a. Thereafter, a heat
treatment is applied to the rod 90 at a temperature of more than
+35 degree C. and the deformed hooks 92 of the rod 90 are returned
back to the memorized original shape and are rigidly fixed to the
head 81. After the rod 90 is inserted into the pedicle screw 80,
the bolt 83 is joined to the thread hole 81b of the head 81 for
tightening the rod 90 to the pedicle screw 80.
[0146] A further embodiment of the present invention will be
described in detail referring to FIG. 22.
[0147] This embodiment makes the connecting work simple, by simply
coupling the rod to the pedicle screw after a plurality of the
pedicle screws are installed in the pedicles of the vertebras.
[0148] Referring now to FIG. 22a, the detailed description of the
pedicle screw will be omitted because the structure of the pedicle
screw 40 is the same as that in an above-mentioned embodiment. The
same reference numerals denote the same elements as illustrated in
the prior embodiment.
[0149] A rod segment 100 of this embodiment is formed in a "U"
shape. The U-shaped rod segment 100 is put into the rod grooves 42
and 42' of the head 41, after the pedicle screws 40 is inserted
into a pedicle of the vertebras. The connection of the rod segment
100 is achieved by tightening the set screw 44 to the reception
cavity 41a of the head 41 in order to fix the rod segment 100 to
the pedicle screw 40. If the pedicle screws 40 are not well
aligned, the U-shaped rod segment 100 may be deformed to comply
with the misaligned pedicle screw 40. Accordingly, the deformed rod
segment 100 is easily positioned in the rod grooves 42 and 42' of
the reception cavity 41a of the head 41. The deformed rod segment
100 may be returned back to the original shape according to a
memorized shape of the rod segment 100, thereby correcting a
position of the misaligned pedicle screw 40.
[0150] The U-shaped rod segment 100 can be replaced with straight
bar type rod segments 101 and 101' as shown in FIG. 22b. An elastic
section 102 may be provided in the middle of the straight rods
segment 101 and 101'. The straight rod segments 101 and 101' are
respectively and alternately set to the rod grooves 42 and 42'
which are positioned in the reception cavity 41a. Therefore, in the
case wherein the straight rod segments 101 and 101' having elastic
section 102 are used, it is not necessary to have an additional
connector for such a serial connection.
[0151] Another embodiment of the present invention will be
described in detail referring to FIGS. 23 to 26.
[0152] Referring now to FIGS. 23 to 25, this embodiment comprises
at least one pedicle screw 110, a pair of stapling rods 120, and a
middle connecting rod 140.
[0153] Referring now to FIG. 25, the pedicle screw 110 has a head
111 at the top portion thereof and a thread 113 formed below the
head 111 to be implanted into the pedicle of the vertebra, wherein
the head 111 has a reception cavity 111a and first and second
sockets 112 and 112' formed in the bottom surface of a reception
cavity 111a.
[0154] The rod 120 is formed in a staple structure for preventing a
movement of the vertebra.
[0155] One side of the staple rod 120 is directly implanted into
the pedicle of the vertebra and other side thereof is inserted into
one of the sockets 112 and 112'.
[0156] The middle connecting rod 140 is employed for serially
connecting the staple rod 120 to the pedicle screw 110 by inserting
both ends thereof to the sockets 112 and 112' of the head 111,
respectively.
[0157] Referring to FIG. 24, the staple rod 120 has a first bridge
121 for providing a space between selected vertebra and adjacent
vertebra, an elastic section 126 formed in the middle of the first
bridge 121, a spike 122 downwardly extended from one end of the
first bridge 121 to be implanted directly into the pedicle of the
vertebra, and a first connecting pole 123 downwardly extended from
the other end of the first bridge 121 to be fixed to the pedicle
screws 110. The length of the first connecting pole 123 is shorter
than the depth of the reception cavity 111a of the head 111 so that
the first connecting pole 123 is inserted into the socket 112 of
the pedicle screw 110. The spike 122 has a plurality of scarred
regions 125 for preventing the spike 122 from being detached from
the pedicle of the vertebra. The scarred regions 125 may be formed
by an electro discharge machine. The diameter of the staple rod 120
is approximately in a range of 2 to 7 mm and it can be adjusted on
a basis of unit diameter of 0.5 mm.
[0158] Once a spinal fusion has been finished, the staple rod 120
is not separated from the vertebra because the scarred regions 125
are buried in the vertebra.
[0159] According to an embodiment of the present invention, it is
possible to make a connection among three adjacent vertebras, using
two staple rods 120 and one pedicle screw 110.
[0160] The middle connecting rod 140 has a second bridge 141 for
providing a space between the pedicle screws 110, an elastic
section 146 formed in the middle of the second bridge 141, and
second connecting poles 142 downwardly extended from both ends of
the second bridge 141, wherein the length of the second connecting
poles 142 is shorter than the depth of the reception cavity 111a of
the head 111. The reason for this is that a volume should be
prepared for the insertion of a fixing member such as a set
screw.
[0161] The first connecting pole 123 of the staple rod 120 and the
second connecting poles 142 are substantially equal to each other.
In the serial connection, one of the second connecting poles 142
extended at both ends of the middle connecting rod 140 is inserted
into the socket 112 of head 111 of the pedicle screw 110 and the
other is inserted into the socket 112' of head 111' of the adjacent
pedicle screw 110'.
[0162] The elastic sections 126 and 146 can be made up of a coil
spring or a wave shape element. The diameter of each elastic
section 126 and 146 is substantially the same as that of first and
second bridge 121 and 141.
[0163] In this embodiment, at least one set screw 130 is joined to
the reception cavity 111a of the head 111 of the pedicle screws 110
for preventing a movement of the staple rod 120.
[0164] Likewise, in this embodiment, at least one head cap 131 is
adopted to the upper surface of the head 111. The head cap 131 is
provided to improve holding power of the staple rod 120 without an
additional rod such as a fastening element.
[0165] Hereinafter, an installation procedure of the staple rod 120
among the first to fourth vertebras will described in detail.
[0166] Referring to FIGS. 23 and 26, the first and second pedicle
screws 110 and 110' are implanted into second and third middle
vertebras, respectively. The first connecting pole 123 of the first
staple rod 120 is inserted into one of the sockets 112 and 112' of
the first pedicle screw 110 and another connecting bar (123') of
the second staple rod 120' is inserted into the socket 112'' of the
second pedicle screw 110'.
[0167] The spikes 122 and 122' of the first and second staple rods
120 and 120' are implanted into the first vertebra and forth
vertebra, respectively. The two second connecting poles 142 at both
sides of the middle connecting rod 140 are inserted into the
sockets 112' an 122'' of the first and second pedicle screws 110
and 110, respectively.
[0168] After the installation of the staple rods 120 and 120' and
the middle connecting rod 140, the outer thread 130a of the set
screw 130 is joined to the reception cavity 110a of the head 110
and the set screw 130 is then joined to the inner thread 10b of the
reception cavity 110a by a wrench tool. Accordingly, the staple rod
120 and the middle connecting rod 140 are simultaneously pressed by
the set screw 130 so that the staple rod 120 and the middle
connecting rod 140 are securely and rigidly fixed in the pedicle
screw 110. Although the pedicle screws 110 and 110' are not well
aligned, the staple rods 120 are easily and simply connected to the
pedicle screw 110. This can be further achieved by the deformation
of the staple rods 120 and the middle connecting rod 140.
[0169] Before the first connecting poles 123 and 123' of the first
and second staple rods 120, 120' are inserted into the sockets 112,
112' of the head 111, the staple rod 120 can be deformed at a phase
transformation point (+10 degree C. and below) on condition that
one end of the first staple rod 120 is optimally connected to the
socket 112 of the head 111. Further, the spikes 122 and 122' of the
deformed first and second staple rods 120 and 120' are implanted
into bores of the vertebras. Also, the first connecting poles 123
and 123' of the first and second deformed staple rods 120 and 120'
are joined to the sockets 112 and 112' of the head 111. Finally,
the rod connection is completed among the pedicle screws 110 and
110', the staple rods 120 and 120' and the middle connecting rod
140.
[0170] Next, a heat treatment may be applied to the staple rods 120
and the middle connecting rod 140 at a restoration point (+35
degrees C. and over), using a surgical tool having a heating
source. The lengthened elastic sections 126 and 146 are returned
back to the memorized original shape and are transformed to an
austenite phase.
[0171] At this time, the first and second connecting poles 123 and
142, the staple rod 120 and the middle connecting rod 140 are
rigidly fixed to the sockets 112 and 112' of the head 110, during
the restoration to the memorized original shape.
[0172] According to this embodiment, a movement between spinal
segments is given by the superelastic action of the elastic section
126 and 146, which are respectively formed in the staple rod 120
and the middle connecting rod 140, when the patient bends or
wrenches his back after the spinal fusion.
[0173] According to the structure of the above-mentioned
embodiment, the first and second staple rods 120 and 120' are
formed in a symmetric structure. Thus, it is necessary to have four
pedicle screws even though all of them are needed in the
conventional spinal fixation system; however, it is necessary to
have only two pedicle screws in this embodiment. Therefore,
according to this embodiment, the number of pedicle screw is
reduced. In particular, in case of the correction of two vertebras,
it may be possible to perform the correcting work of the vertebras
by using only one single staple rod 120 without an additional
pedicle screw. In case of correction of three vertebras, it is
necessary to have only one pedicle screw.
[0174] Another embodiment of the present invention will be
described in detail referring to FIGS. 27 and 28.
[0175] In this embodiment, the staple rod 150 is directly implanted
into the pedicle of the vertebra without any pedicle screw.
[0176] Referring now to FIGS. 27 and 28, at least one staple rod
150 is located at both laterals of the spine.
[0177] The staple rod 150 has a bridge 152 for providing a space
between a selected vertebra and an adjacent vertebra, a spike 153
extending downwardly from both ends of the bridge 152 for
implantation into the pedicle of the vertebra, and an elastic
section 154 formed in the bridge 152.
[0178] The elastic section 154 can be made of a coil spring (see
FIG. 27) or a wave shape element or a S-shaped element (see FIG.
28). Also, The spike 153 has a plurality of scarred regions 155
which prevents the spike 153 from being detached from the pedicle
of the vertebra.
[0179] The scarred regions 125 may be formed by an electro
discharge machine.
[0180] Although the preferred embodiments of the invention have
been disclosed for illustrative purposes, those skilled in the art
will appreciate that various modifications, additions and
substitutions are possible, without departing from the scope and
spirit of the invention as disclosed in the accompanying
claims.
[0181] According to the various embodiments of the present
invention, the rod segments may be made from any suitable material,
including surgical grade titanium alloys. The transverse links may
made of a shape memory alloy, such as for example Nitinol alloy
(Ni--Ti alloy) which has superelastic characteristics. Although the
pedicle screws are out of alignment during the surgery, embodiment
of the present invention can easily and simply make a structural
connection between the rods and the pedicle screws without
excessive force on the spine and/or implants.
[0182] In addition, in the present invention, the rod sections
and/or transverse links may have an elastic section in an optional
range thereof. The elastic portion of the rod allows a delicate
movement after the spinal segments fuse. Thus, it disperses a load,
which is put on the spinal segments which have been fused, through
the rods and the transverse links having flexibility. As a result,
a burden on lumbar vertebra may be reduced. Also, the use of a
spinal fixation apparatus according to an embodiment of the present
invention may have the effect of decreasing complications that can
arise between an upper segment and a lower segment.
* * * * *