U.S. patent application number 11/319427 was filed with the patent office on 2006-05-18 for bone screw.
This patent application is currently assigned to Biedermann Motech GmbH. Invention is credited to Lutz Biedermann, Jurgen Harms.
Application Number | 20060106383 11/319427 |
Document ID | / |
Family ID | 26007628 |
Filed Date | 2006-05-18 |
United States Patent
Application |
20060106383 |
Kind Code |
A1 |
Biedermann; Lutz ; et
al. |
May 18, 2006 |
Bone screw
Abstract
A bone screw having a screw member possessing a threaded section
and a head and a receiving part at the head end for receiving a rod
to be connected to the bone screw is provided. The receiving part
has on open first bore and a substantially U-shaped cross-section
having two free legs provided with a thread. Furthermore, the
receiving part has a second bore on the end opposite to the first
bore whose diameter is greater than that of the threaded section
and smaller than that of the head. On the bottom of the first bore
a seat for the head is provided. In order that the screw member can
be pivoted to at least one side by an enlarged angle, the edge
bounding the free end of the second bore viewed relative to the
axis of the first bore is of asymmetric construction.
Inventors: |
Biedermann; Lutz;
(VS-Villingen, DE) ; Harms; Jurgen; (Karlsruhe,
DE) |
Correspondence
Address: |
MORRISON & FOERSTER LLP
1650 TYSONS BOULEVARD
SUITE 300
MCLEAN
VA
22102
US
|
Assignee: |
Biedermann Motech GmbH
VS-Schwenningen
DE
|
Family ID: |
26007628 |
Appl. No.: |
11/319427 |
Filed: |
December 29, 2005 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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10763431 |
Jan 22, 2004 |
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11319427 |
Dec 29, 2005 |
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10037698 |
Nov 9, 2001 |
6736820 |
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10763431 |
Jan 22, 2004 |
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Current U.S.
Class: |
606/301 ;
606/266; 606/278; 606/308; 606/328 |
Current CPC
Class: |
A61B 17/7037 20130101;
A61B 17/8605 20130101; A61B 17/7038 20130101; A61B 17/7067
20130101; A61B 17/7032 20130101 |
Class at
Publication: |
606/061 |
International
Class: |
A61F 2/30 20060101
A61F002/30 |
Foreign Application Data
Date |
Code |
Application Number |
Dec 27, 2000 |
DE |
100 65 397.9 |
Nov 10, 2000 |
DE |
100 55 888.7 |
Claims
1. A bone fixation assembly comprising: a coupling element having
an inner surface defining a first bore coaxial with a first
longitudinal axis and a second bore coaxial with a second
longitudinal axis, wherein said first and second longitudinal axes
intersect and are in communication with one another; and an
anchoring element assembled with said coupling element, said
anchoring element having a first end for insertion into bone.
2. The assembly of claim 1, wherein said coupling element has an
upper end and a lower end, said first bore extending from said
upper end toward said lower end and said second bore extending from
said lower end toward said upper end.
3. The assembly of claim 2, wherein said first and second bores are
in communication with one another between said upper and lower ends
of said coupling element.
4. The assembly of claim 2, wherein said upper end of said coupling
element defines a first plane and said lower end of said coupling
element defines a second plane, and wherein said first and second
planes intersect one another.
5. The assembly of claim 2, wherein said anchoring element projects
from said lower end of said coupling element.
6. The assembly of claim 1, wherein said anchoring element is a
separate member assembled with said coupling element so that said
coupling element and said anchoring element are movable relative to
one another.
7. The assembly of claim 2, wherein said second bore includes a
seat adjacent said lower end of said coupling element, and wherein
said seat is adapted to engage said anchoring element.
8. The assembly of claim 7, wherein said anchoring element has a
head having a substantially spherical underside adapted to engage
said seat.
9. The assembly of claim 8, wherein said seat has a substantially
concave surface adapted to engage the spherical underside of said
head.
10. The assembly of claim 8, further comprising a locking element
engageable with said coupling element for locking the position of
said coupling element with respect to said anchoring element.
11. The assembly of claim 10, wherein said locking element urges a
stabilizing rod toward said lower end of said coupling element
which in turn forces said head of said anchoring element against
said seat for locking said coupling element and said anchoring
element from further movement relative to one another.
12. The assembly of claim 11, wherein said seat is defined by an
interior wall of said coupling element.
13. The assembly of claim 1, wherein said coupling element has an
exterior surface, an upper end and a lower end, said rod-receiving
openings extending from said upper end toward said lower end, and
wherein said coupling element comprises etes cuts between said
exterior surface and said rod-receiving openings for minimizing the
width of said coupling element.
14. The assembly of claim 1, wherein said anchoring element is a
screw fastener having screw threads extending from said first end
toward a second end thereof.
15. The assembly of claim 3, wherein said anchoring element has a
head with a substantially spherical shape and said coupling element
has a seat adjacent said lower end thereof, and wherein said
spherical head is adapted to engage said seat.
Description
REFERENCE TO RELATED APPLICATIONS
[0001] This application is a continuation of Ser. No. 10/763,431,
filed Jan. 22, 2004, which is a continuation of Ser. No.
10/037,698, filed Nov. 9, 2001, now U.S. Pat. No. 6,736,820, the
disclosures of which are incorporated herein by reference.
FIELD AND BACKGROUND OF THE INVENTION
[0002] The invention relates to a bone screw having a threaded
section and a head and a receiving part at the head end for
receiving a rod to be connected to the bone screw, the receiving
part possessing an open first bore and a substantially U-shaped
cross-section having two free legs provided with a thread and a
second bore at the end opposite to the first bore, whose diameter
is greater than that of the threaded section and smaller than that
of the head and which forms the seat for the head, and a nut or
screw working together with the thread.
[0003] Such a bone screw is disclosed, for example, in U.S. Pat.
No. 5,672,176. In the known bone screw the head is of spherical
segment-shaped construction. The bottom of the first bore adjacent
to the second bore is likewise of spherical segment-shaped
construction so that the spherical head lies on this spherical
section. The plane going through the bounding edge is oriented at
right angles to the axis of the first bore and the mid-point of the
second bore coincides with the axis of the first bore. By this
means it is achieved that the threaded section possessing the head
is pivotable in a predetermined angle of generally up to 25.degree.
about the axis of the first bore so that even after screwing the
threaded section into a vertebral segment orientation of the
receiving part receiving a rod is possible. At the same time, the
size of the pivot angle is limited to the extent that the second
bore as a function of the diameter of the head must not exceed d
certain size so that the head still has an adequate hold in the
receiving part.
[0004] The use of such bone screws is something of a problem in the
region of cervical vertebrae. In this case, due to the small
dimensions of the cervical vertebrae, it is necessary that the
screws must always be pivoted to one side and upwards, a greater
degree of pivoting being necessary than is the case in the larger
thoracic vertebrae and lumbar vertebrae.
SUMMARY OF THE INVENTION
[0005] The aim of the invention is to provide a bone screw which
permits a larger pivot angle. This task is solved by a bone screw
having a screw member that possess a threaded section, a head and a
receiving part at the head end for receiving a rod to be connected
to the bone screw. The receiving part has an open first bore and a
substantially U-shaped cross-section having two free legs provided
with threads, a second bore at the end opposite the first bore
having a diameter greater than the diameter of the threaded section
and smaller than the diameter of the head, and a seat for the head
and a nut or screw acting together with the thread. When viewed
relative to the axis of the first bore, the edge bounding the free
end of the second bore is asymmetrical.
[0006] Refinements of the invention are identified in the more
detailed embodiments described below.
BRIEF DESCRIPTION OF THE DRAWINGS
[0007] Further features and practical advantages of the invention
emerge from the description of exemplified embodiments with
reference to the figures.
[0008] FIG. 1 depicts a side elevation of a first embodiment of the
invention, partly in sectional representation.
[0009] FIG. 2 shows an enlarged detail of FIG. 1.
[0010] FIG. 3 depicts a side elevation, partly in sectional
representation, of a second embodiment of the invention.
[0011] FIG. 4 depicts a corresponding representation of a further
embodiment of the invention.
DETAILED DESCRIPTION OF THE INVENTION
[0012] The bone screw includes a screw member proper 1 having a
threaded section 2 and a head 3. The head is formed in the shape of
a segment of a sphere in the region adjoining the threaded section.
Coaxial with the thread axis and on the end opposite to the
threaded section 2 the head possesses a recess 4 for engagement
with a socket screw key.
[0013] The bone screw further comprises a cylindrically constructed
receiving part 5. At one end this has a first bore 6 of axially
symmetrical construction. On the opposite end a second bore 7 is
provided whose diameter is greater than that of the threaded
section 2 and smaller than that of the head 3. On the end opposite
to the second bore the first bore is open and its diameter is of
such a size that that the screw member 1 can be guided through the
open end by its threaded section 2 going through this bore and by
the head going as far as the bottom of the first bore. The bottom
of the first bore is constructed as a spherically shaped region
towards the open end, the radius being substantially equal to the
radius of the spherical segment-shaped section of the head 3.
Furthermore, the receiving part 5 has a U-shaped recess 8 arranged
symmetrically relative to the center of the part whose bottom is
directed towards the second bore 7 and whose two side legs 13, 14
extend to the open end directed towards the first bore 6. At the
free end of the legs 13, 14 a thread for engagement with a screw
member constructed as a nut or screw is provided. The nut or screw
serves to fix a rod to be inserted into the U-shaped recess 8, it
being possible for the nut or screw to act on the rod directly or
via a pressure member.
[0014] In the embodiment shown in FIGS. 1 and 2, in the direction
of the arrow 9, whose direction lies in a plane going through the
axis of symmetry of the first bore and which is inclined to the
axis of symmetry by a predetermined angle, a circular countersink
10 is made in the edge between the opening plane 11 of the second
bore and the edge 12--of the first bore.
[0015] In this manner, as can be seen in the figures, it is
achieved that the angle between the axis of the screw member 1 and
the axis of symmetry of the first bore is substantially enlarged by
comparison with the angle otherwise attainable. At the same time
the seat of the screw member 1 in the receiving part is
retained.
[0016] In the second embodiment shown in FIG. 3 the interior of the
receiving part 5 is constructed as in the first embodiment. The
opening plane 11, which bounds the second bore 7, in this
embodiment is inclined at a predetermined angle .alpha. to the
plane bounded by the second bore 7 so that the normal to this plane
11 and the axis of symmetry of the first bore 15 enclose the angle
of inclination. In the case shown this angle .alpha. is 15.degree.
as an exemplified embodiment. In this version it is also achieved
that the screw member 1 is pivotable in the direction shown by an
angle to the axis of symmetry of the-first-bore which is
substantially greater than the angle which is achievable in the
usual mode of construction.
[0017] Both in the embodiment shown in FIG. 1 and the embodiment
shown in FIG. 3 the countersink or chamfer is selected in such a
way that in each case a small peripheral section still remains
which still belongs to the spherical seat.
[0018] In a fourth embodiment which is not shown the mid-point of
the second bore is constructed offset to the side to a small
extent, for example by 0.5 mm, relative to the axis of symmetry of
the first bore. This lateral offsetting in turn produces the result
that the head is held in the mounting formed by the spherically
constructed bottom but a greater pivot width is achieved in a side
direction.
[0019] In the exemplified embodiments described above four
different approaches to a solution are presented. It is also
possible to combine the individual approaches with one another;
that is, for example, to combine the solution according to the
first and second exemplified embodiments or one of the two with the
third and/or fourth exemplified embodiment, or even all four
exemplified embodiments in order to achieve, in this way, a still
greater possibility for pivoting in at least one direction.
[0020] In the exemplified embodiments described above the spherical
bottom of the first bore 6 is constructed in each case as an
integral component of the receiving part 5. In a modified
embodiment, however, the spherical bottom can also be provided
either in a mounting part introduced through the first bore 6 or in
a mounting part introduced through the second bore 7. The invention
is then used in a corresponding manner to the end that the
receiving part together with the insert piece is regarded as one
member and the measures described above are taken on this piece
assembled in this way.
[0021] The members forming the bone screw are preferably made of
titanium.
[0022] In the embodiment shown in FIG. 4 the edge bounding the free
end of the second bore viewed relative to the axis of the first
bore is of symmetrical construction. The asymmetry is achieved in
that the screw 1 has a recess or countersink 16 on its neck
engaging on the sphere or the spherical segment so that in the
manner shown in FIG. 4 as in the exemplified embodiments previously
described the enlarged pivot angle can be achieved.
* * * * *