U.S. patent application number 13/764048 was filed with the patent office on 2013-06-13 for three-dimensional guide for wire for forming pedicle screw insertion hole and method of producing the same.
This patent application is currently assigned to National University Corporation University of Toyama. The applicant listed for this patent is National University Corporation University of Toyama. Invention is credited to Yoshiharu KAWAGUCHI.
Application Number | 20130145812 13/764048 |
Document ID | / |
Family ID | 45567675 |
Filed Date | 2013-06-13 |
United States Patent
Application |
20130145812 |
Kind Code |
A1 |
KAWAGUCHI; Yoshiharu |
June 13, 2013 |
THREE-DIMENSIONAL GUIDE FOR WIRE FOR FORMING PEDICLE SCREW
INSERTION HOLE AND METHOD OF PRODUCING THE SAME
Abstract
A three-dimensional guide for a wire for forming a pedicle screw
insertion hole is produced based on a CT image of a spine, and
includes a contact surface section that comes in surface contact
with a morphological surface of a bone at an insertion site, and a
guide block section that is provided upright from the contact
surface section. The guide block section has a guide hole that
restricts the insertion direction of the wire. The guide hole has
an inner diameter slightly larger than the outer diameter of the
wire. The guide hole has a length of 15 to 30 mm to restrict the
insertion position and the insertion direction of the wire.
Inventors: |
KAWAGUCHI; Yoshiharu;
(Toyama, JP) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Toyama; National University Corporation University of |
Toyama-shi |
|
JP |
|
|
Assignee: |
National University Corporation
University of Toyama
Toyama-shi
JP
|
Family ID: |
45567675 |
Appl. No.: |
13/764048 |
Filed: |
February 11, 2013 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
PCT/JP2011/067955 |
Aug 5, 2011 |
|
|
|
13764048 |
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Current U.S.
Class: |
72/372 ;
140/123 |
Current CPC
Class: |
B21F 1/00 20130101; A61B
17/1703 20130101; A61B 17/1757 20130101 |
Class at
Publication: |
72/372 ;
140/123 |
International
Class: |
B21F 1/00 20060101
B21F001/00 |
Foreign Application Data
Date |
Code |
Application Number |
Aug 12, 2010 |
JP |
2010-181119 |
Claims
1. A three-dimensional guide for a wire for forming a pedicle screw
insertion hole that is produced based on a CT image of a spine, the
three-dimensional guide comprising: a contact surface section that
comes in surface contact with a morphological surface of a bone at
an insertion site; and a guide block section that is provided
upright from the contact surface section, the guide block section
having a guide hole for the wire, and the guide hole having an
inner diameter slightly larger than an outer diameter of the wire,
and having a length of 15 to 30 mm to restrict an insertion
position and an insertion direction of the wire.
2. The three-dimensional guide as defined in claim 1, the contact
surface section including a morphological surface section that is
formed by a gradual irregular curved surface that corresponds to
the morphological surface of the bone at the insertion site, and a
process contact section that is formed by a steep slope and comes
in contact with a process of a vertebral arch.
3. A method of producing a three-dimensional guide for a wire for
forming a pedicle screw insertion hole, the method comprising:
extracting a pedicle screw insertion site based on a CT image of a
spine; producing a mold based on the extracted pedicle screw
insertion site; and molding the three-dimensional guide in the
mold, the three-dimensional guide including a contact surface
section that comes in surface contact with a morphological surface
of a bone at the insertion site, and a guide block section that has
a guide hole for restricting an insertion position and an insertion
direction of the wire.
4. The method as defined in claim 3, the molding of the
three-dimensional guide including molding the contact surface
section in the mold so that the contact surface section includes a
morphological surface section that is formed by a gradual irregular
curved surface that corresponds to the morphological surface of the
bone at the insertion site, and a process contact section that is
formed by a steep slope and comes in contact with a process of a
vertebral arch.
Description
CROSS REFERENCE TO RELATED APPLICATION
[0001] This application is a continuation of International Patent
Application No. PCT/JP2011/067955, having an international filing
date of Aug. 5, 2011, which designated the United States, the
entirety of which is incorporated herein by reference. Japanese
Patent Application No. 2010-181119 filed on Aug. 12, 2010 is also
incorporated herein by reference in its entirety.
BACKGROUND
[0002] The present invention relates to a three-dimensional guide
for a wire for forming a pedicle screw insertion hole that may
suitably be used to insert a pedicle screw used for spinal surgery
into an anatomically appropriate site, and a method of producing
the same.
[0003] Spinal bones allow a motion or movement in an arbitrary
direction while surrounding and protecting a number of veins,
arteries, nerves, and the like.
[0004] An adult human spine is made up of more than twenty distinct
bones that are joined through a posterior intervertebral joint and
a cartilage plate (intervertebral disc) that are positioned between
adjacent vertebrae.
[0005] The spinal bones are anatomically classified into cervical
vertebrae, thoracic vertebrae, lumbar vertebrae, and sacral
vertebrae.
[0006] The cervical vertebrae, the thoracic vertebrae, the lumbar
vertebrae, and the sacral vertebrae form a specific curvature
referred to as a cervical lordosis, a thoracic kyphosis, a lumbar
flexure, and a sacral kyphosis.
[0007] A pedicle screw may be used during spinal surgery in order
to achieve a therapeutic effect by securing the spine.
[0008] However, since the configuration of the spine significantly
differs among individuals, and the spine may be deformed to a large
extent in patients who suffer from scoliosis or the like, a severe
complication may occur when inserting a pedicle screw. For example,
quadriplegia due to spinal injury and death due to vertebral artery
injury have been reported.
[0009] A CT cutout technique that develops a life-sized CT image,
draws the insertion position and the insertion angle of a pedicle
screw directly on the CT film, and cuts the CT film along the
insertion line and the posterior margin of the lamina has been
proposed in The journal of the Japan Spine Research Society 19(1),
2008, p. 31 (author: Hiroshi Miyamoto).
[0010] The CT cutout technique can accurately obtain the insertion
position, but does not reliably ensure the stability of the
insertion direction.
SUMMARY
[0011] The invention may provide to a three-dimensional guide for a
wire that is used to form an insertion hole for inserting a pedicle
screw at an anatomically appropriate position, and a method of
producing the same.
[0012] According to one aspect of the invention, there is provided
a three-dimensional guide for a wire for forming a pedicle screw
insertion hole that is produced based on a CT image of a spine, the
three-dimensional guide including a contact surface section that
comes in surface contact with a morphological surface of a bone at
an insertion site, and a guide block section that is provided
upright from the contact surface section, the guide block section
having a guide hole for restricting an insertion direction of the
wire.
[0013] It is necessary to form a pedicle screw insertion hole
having an anatomically appropriate depth in the pedicle of
vertebral arch in an anatomically appropriate direction when
inserting a pedicle screw into the pedicle of vertebral arch.
[0014] In this case, a K-wire is inserted into the pedicle of
vertebral arch, and a preliminary hole is formed in the pedicle of
vertebral arch along the K-wire inserted into the pedicle of
vertebral arch using a hollow drill.
[0015] The drill is then removed while allowing the K-wire to
remain, and a thread is formed in the inner circumference surface
of the preliminary hole along the K-wire using a hollow tap.
[0016] One aspect of the invention provides a three-dimensional
guide that contributes to stabilization of the insertion position
and the insertion direction of the K-wire.
[0017] Since the vertebral arch has processes such as a transverse
process, a spinous process, and a articular process, it is
preferable that the contact surface section include a morphological
surface section that corresponds to the morphological surface of
the bone at the insertion site, and a process contact section that
comes in contact with the process of the vertebral arch so that the
position of the three-dimensional guide is stabilized during
surgery. It is preferable that the guide hole have a length of
about 15 to about 30 mm from the viewpoint of insertion
stability.
[0018] If the length of the guide hole is less than 15 mm, the
insertion direction may become unstable. If the length of the guide
hole exceeds 30 mm, the height of the guide block increases
although the insertion direction becomes stable.
[0019] The three-dimensional guide may be produced by a method that
includes capturing a CT image of a spine, extracting a pedicle
screw insertion site based on the CT image, designing the shape of
a block that has a contact surface section that corresponds to the
morphological surface of the bone at the extracted insertion site,
producing a mold based on the designed shape, and molding the
three-dimensional guide in the mold.
[0020] Since the three-dimensional guide according to one aspect of
the invention includes the contact surface section that comes in
surface contact with the morphological surface of a bone, and the
guide hole that three-dimensionally guides the insertion direction
of the wire, a pedicle screw can be safely inserted into an
appropriate site (part) of a spine in a stable manner.
BRIEF DESCRIPTION OF THE DRAWINGS
[0021] FIG. 1 illustrates an example of a bone model of cervical
vertebrae, and an example of a three-dimensional guide that is
produced to come in surface contact with the morphological surface
of the bone.
[0022] FIGS. 2A and 2B illustrate an example in which a
three-dimensional guide according to one embodiment of the
invention is brought into contact with cervical vertebrae to
position a guide hole, wherein FIG. 2A illustrates a state before
the three-dimensional guide is brought into contact with cervical
vertebrae, and FIG. 2B illustrates an example in which a guide hole
13 is positioned by fitting a process contact section 14 to a
process 2 of the bone.
[0023] FIGS. 3A and 3B are side views illustrating cervical
vertebrae, and illustrate an example in which the insertion
direction of a K-wire is determined using a guide hole 13 so that a
vertebral artery 3 is not damaged, wherein FIG. 3A illustrates a
state before the three-dimensional guide is brought into contact
with cervical vertebrae, and FIG. 3B illustrates a state after the
three-dimensional guide has been brought into contact with cervical
vertebrae.
[0024] FIGS. 4A to 4C are cross-sectional views illustrating the
positional relationship between a pedicle of vertebral arch and a
three-dimensional guide, wherein FIG. 4A illustrates a state before
the three-dimensional guide is brought into contact with the
pedicle of vertebral arch, FIG. 4B illustrates a state in which a
process contact surface 14a of the three-dimensional guide that is
in the shape of a recess is brought into contact with a process 2
of the bone, and FIG. 4C is a bottom view illustrating the
three-dimensional guide.
[0025] FIGS. 5A and 5B are front views illustrating a state in
which a three-dimensional guide is brought into contact with a
pedicle of vertebral arch, wherein FIG. 5A is a partial
cross-sectional view illustrating a state before the
three-dimensional guide is brought into contact with a pedicle of
vertebral arch, and FIG. 5B is a partial cross-sectional view
illustrating a state after the three-dimensional guide has been
brought into contact with the pedicle of vertebral arch.
[0026] FIGS. 6A to 6C illustrate a state in which a K-wire is
inserted along a guide hole formed in a three-dimensional guide,
wherein FIG. 6A illustrates a state before the K-wire is inserted,
FIG. 6B illustrates a state after the K-wire has been inserted, and
FIG. 6C illustrates a state in which the three-dimensional guide is
removed from the K-wire.
[0027] FIGS. 7A to 7C illustrate an example in which a pedicle is
drilled into a pedicle of vertebral arch along a K-wire using a
hollow drill, wherein FIG. 7A illustrates a state in which the
K-wire is inserted into a hollow section of a drill, FIG. 7B
illustrates a state during drilling, and FIG. 7C illustrates a
state after a preliminary hole P.sub.1 has been formed.
[0028] FIGS. 8A to 8C illustrate an example in which the inner
circumference surface of a preliminary hole is tapped along a
K-wire using a hollow tap, wherein FIG. 8A illustrates a state in
which the K-wire is inserted into the tap, FIG. 8B illustrates a
state during tapping, and FIG. 8C illustrates a state after a
pedicle screw insertion threaded hole has been formed.
[0029] FIGS. 9A to 9C illustrate an example in which a pedicle
screw is inserted into an insertion threaded hole formed in a
pedicle of vertebral arch using a dedicated driver, wherein FIG. 9A
illustrates a state before the pedicle screw is inserted, FIG. 9B
illustrates a state after the pedicle screw has been inserted, and
FIG. 9C illustrates a state after the driver has been removed.
[0030] FIG. 10 illustrates an example in which a plurality of
pedicle screws are connected using a rod.
DESCRIPTION OF EXEMPLARY EMBODIMENTS
[0031] A three-dimensional guide according to one embodiment of the
invention may be applied to an arbitrary part of a spine. An
example in which the three-dimensional guide is applied to cervical
vertebrae is described below.
[0032] The configuration (morphology) of the bones in the operative
site is captured as a CT image, and a bone model A (see FIG. 1) is
formed using plaster or the like.
[0033] Since a spine has a complex configuration in which vertebral
arches are joined through an intervertebral disc, an anatomically
appropriate insertion direction and insertion depth of a pedicle
screw are determined using the bone model A and the CT image.
[0034] A spinal bone (vertebral arch) 1 has processes 2 (e.g.,
transverse process, spinous process, and articular process), and
the surface of each bone has a complex and irregular
configuration.
[0035] As illustrated in FIGS. 3A to 4B, a vertebral artery 3
passes through the spinal bone 1.
[0036] When the insertion site and the insertion direction have
been anatomically determined taking account of the above situation,
the shape of a plurality of (three in FIG. 1) three-dimensional
guides 10, 10A, and 10B is determined based on the CT image.
[0037] When determining the shape of the three-dimensional guides
10, 10A, and 10B, it is necessary to set the size of contact
surface sections 11, 11A, and 11B that come in surface contact with
the bone along the irregular configuration of the bone at the
insertion site, and the shape and the size of guide block sections
12, 12A, and 12B.
[0038] The following description focuses on the three-dimensional
guide 10, and description of the three-dimensional guides 10A and
10B is omitted (corresponding reference signs are used for the
three-dimensional guides 10A and 10B in the drawings).
[0039] The contact surface section 11 may have a process contact
section 14 that comes in contact with the process (spinous process)
2 of the vertebral arch so that the three-dimensional guide 10 can
be positioned by merely bringing the three-dimensional guide 10
into contact with the vertebral arch.
[0040] According to this configuration, the three-dimensional guide
10 is necessarily accurately positioned, and is not shifted due to
the shape of the contact surface section (may be referred to as
"morphological surface section") 11 that is formed by a gradual
irregular curved surface that corresponds to the morphological
surface (morphology) of the bone at the insertion site, and the
shape of the process contact section 14 that is formed by a steep
slope, by merely placing the three-dimensional guide 10 in the
vicinity of the insertion site.
[0041] Since it is necessary to pull out the three-dimensional
guide 10 after inserting a K-wire in order to form an insertion
hole for inserting the pedicle screw, the contact surface section
11 and the process contact section 14 are designed so that an
undercut section is not formed.
[0042] In one embodiment of the invention, the process contact
section 14 has a process contact surface 14a that is in the shape
of a recess that corresponds to the shape of the spinous process 2
(see FIGS. 4A to 4C, 5A, 5B, and 6A). Note that the configuration
is not limited thereto as long as the three-dimensional guide 10
can be effectively positioned.
[0043] A guide hole 13 is formed in the guide block section 12 to
restrict the insertion direction of a K-wire 20 while guiding the
K-wire 20.
[0044] After the shape of the three-dimensional guide 10 has been
determined, a mold that has the determined shape is produced.
[0045] A resin or the like is injected into the mold to produce a
three-dimensional guide having a given shape.
[0046] The insertion position and the insertion direction of the
K-wire can be accurately determined by placing the
three-dimensional guide 10 thus produced at the insertion site of
the spine.
[0047] A method of forming a pedicle screw insertion hole using the
three-dimensional guide 10 is described below.
[0048] FIGS. 2A and 2B are rear views illustrating cervical
vertebrae, and FIGS. 3A and 3B are side views illustrating cervical
vertebrae.
[0049] FIGS. 4A to 4C are cross-sectional views illustrating a
pedicle of vertebral arch, and FIGS. 5A and 5B are enlarged views
illustrating the spinous process 2.
[0050] As illustrated in FIGS. 2A, 3A, 4A, and 5A, the
three-dimensional guide 10 that is produced based on the CT image
includes the process contact section 14 in which the process
contact surface 14a that is in the shape of a recess that
corresponds to the shape of the spinous process 2 is formed, the
contact surface section 11 that comes in contact with the
morphological surface of the bone in an area from the spinous
process 2 to the insertion site of a pedicle screw 50, and the
guide block section 12 in which the guide hole 13 is formed.
[0051] Note that the contact surface section 11 comes in
approximately surface contact with the morphological surface of the
bone. The entire contact surface section 11 need not necessarily
come in contact with the bone.
[0052] When the three-dimensional guide 10 is placed on the
morphological surface of the bone that corresponds to the operative
site, the process contact surface 14a that is in the shape of a
recess is fitted to the spinous process 2 of the bone, and the
contact surface section 11 is fitted to the irregular morphological
surface of the bone in an area from the spinous process 2 to the
guide hole 13, so that the three-dimensional guide 10 is
positioned. Therefore, the insertion direction of the K-wire 20 is
accurately determined by the direction of the guide hole 13 (see
FIG. 6A).
[0053] The K-wire has a diameter of 1 to 2 mm, and the guide hole
13 has an inner diameter slightly larger than the outer diameter of
the K-wire. It is desirable that the guide hole 13 have a length of
15 mm or more.
[0054] The stability of the insertion direction is improved as the
length of the guide hole 13 increases. The length of the guide hole
13 is preferably 30 mm or less from the viewpoint of insertion
operability and producibility of the guide block section 12.
[0055] Since the K-wire 20 is inserted along the guide hole 13 of
the three-dimensional guide 10, the artery 3 and the like are not
damaged.
[0056] When the K-wire 20 has been inserted into the pedicle of
vertebral arch (see FIG. 6B), the three-dimensional guide 10 is
removed from the K-wire 20 (see FIG. 6C).
[0057] A hollow drill 30 is inserted into the pedicle of vertebral
arch along the K-wire 20 while rotating the drill 30 (see FIGS. 7A
and 7B) to form a preliminary hole P.sub.1 (see FIG. 7C).
[0058] A tap 40 (tapping drill) is inserted into the pedicle along
the K-wire 20 and the preliminary hole P.sub.1 while rotating the
tap 40 (see FIGS. 8A and 8B) to form a pedicle screw insertion hole
P.sub.2 having a thread groove (see FIG. 8C).
[0059] An external thread section 50a of the pedicle screw 50 is
screwed into the insertion hole P.sub.2 using a dedicated driver 60
(see FIGS. 9A and 9B), and the driver 60 is removed after the
external thread section 50a has been screwed into the insertion
hole P.sub.2.
[0060] The angle of a head 50b of the pedicle screw 50 thus
inserted is adjusted, and a plurality of pedicle screws 50 are
connected using a rod 70 (see FIG. 10) to secure the bone 1.
[0061] The outer diameter of the external thread section 50a of the
pedicle screw 50 is normally 3.5 to 4 mm.
[0062] The three-dimensional guide 10 may be used in many
institutions in which spinal surgery is performed.
[0063] Although only some embodiments of the present invention have
been described in detail above, those skilled in the art will
readily appreciate that many modifications are possible in the
embodiments without materially departing from the novel teachings
and advantages of this invention. Accordingly, all such
modifications are intended to be included within scope of this
invention.
* * * * *