U.S. patent application number 17/137859 was filed with the patent office on 2021-08-12 for bone anchoring element.
The applicant listed for this patent is BIEDERMANN TECHNOLOGIES GMBH & CO. KG. Invention is credited to Lutz Biedermann, Wilfried Matthis, Helmar Rapp.
Application Number | 20210244456 17/137859 |
Document ID | / |
Family ID | 1000005550320 |
Filed Date | 2021-08-12 |
United States Patent
Application |
20210244456 |
Kind Code |
A1 |
Biedermann; Lutz ; et
al. |
August 12, 2021 |
BONE ANCHORING ELEMENT
Abstract
A bone anchoring element comprising a shaft (2) for anchoring in
a bone, with a plurality of barb elements (7) arranged in at least
one helical line around the shaft axis (M) is described, wherein
said barb elements are elastically movable relative to the shaft.
The bone anchoring element (1) is easy to press into a core hole
bore in a bone. The barb elements (7) act in a similar manner as do
the threads on a conventional bone screw and thus provide for depth
positioning. Moreover, the barb elements at the same time secure
the bone anchoring element and prevent it from sliding-out.
Inventors: |
Biedermann; Lutz;
(VS-Villingen, DE) ; Matthis; Wilfried; (Weisweil,
DE) ; Rapp; Helmar; (Deisslingen, DE) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
BIEDERMANN TECHNOLOGIES GMBH & CO. KG |
Donaueschingen |
|
DE |
|
|
Family ID: |
1000005550320 |
Appl. No.: |
17/137859 |
Filed: |
December 30, 2020 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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15818339 |
Nov 20, 2017 |
10905482 |
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17137859 |
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15093444 |
Apr 7, 2016 |
9861412 |
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15818339 |
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11063049 |
Feb 22, 2005 |
9326804 |
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15093444 |
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60547517 |
Feb 24, 2004 |
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Current U.S.
Class: |
1/1 |
Current CPC
Class: |
A61B 2017/8655 20130101;
A61B 17/7291 20130101; A61B 17/744 20130101; A61B 17/701 20130101;
A61B 17/7007 20130101; A61B 17/866 20130101; A61B 17/7037 20130101;
A61B 17/7266 20130101; A61B 17/864 20130101; A61B 17/7283 20130101;
A61B 17/7032 20130101; A61B 2017/00867 20130101; A61B 17/7098
20130101; A61B 17/68 20130101; A61B 17/7001 20130101; A61B 17/8625
20130101; A61B 17/8685 20130101; A61B 17/74 20130101; A61B 17/746
20130101 |
International
Class: |
A61B 17/86 20060101
A61B017/86; A61B 17/68 20060101 A61B017/68; A61B 17/70 20060101
A61B017/70; A61B 17/72 20060101 A61B017/72; A61B 17/74 20060101
A61B017/74 |
Foreign Application Data
Date |
Code |
Application Number |
Feb 24, 2004 |
DE |
10 2004 009 429.2 |
Claims
1. A bone anchoring element having a shaft for anchoring in a bone,
wherein said shaft comprises a section having a plurality of barb
elements that are arranged around a shaft axis.
2. A bone anchoring element according to claim 1, wherein the barb
elements are elastically deformable relative to a body of the
shaft.
3. A bone anchoring element according to claim 1, wherein each of
the barb elements has a free end cutting edge.
4. (canceled)
5. A bone anchoring element according to claim 1, wherein the barb
elements, viewed in the direction of the shaft axis, are arranged
in at least two axial rows.
6. A bone anchoring element according to claim 1, wherein the
distances between the barb elements in the axial direction are
varied.
7. A bone anchoring element according to claim 1, wherein at least
a part of the section containing the barb elements is made from a
shape memory alloy.
8. A bone anchoring element according to claim 7, wherein the barb
element is made from nitinol.
9. A bone anchoring element according to claim 1, wherein at least
a part of the section containing the barb elements is made from a
body-compatible plastic material.
10-13. (canceled)
14. A bone anchoring element according to claim 1, wherein the
shaft and the barb elements are made of one piece of body
compatible material.
15-17. (canceled)
18. A bone anchoring element according to claim 1, wherein the bone
anchoring element comprises a head that is rigidly connected to the
shaft and is provided to receive a rod.
19. A bone anchoring element according to claim 1, wherein the bone
anchoring element comprises a head that is connected in a pivoting
fashion with a receiver member for receiving a rod.
20. (canceled)
21. A bone anchoring element according to claim 1, wherein the bone
anchoring element is a monoaxial bone screw.
22. A bone anchoring element according to claim 1, wherein the bone
anchoring element is a polyaxial bone screw.
23. A bone anchoring element according to claim 1, including a
second shaft section adjacent to a section containing the barb
elements.
24-53. (canceled)
54. A bone anchoring element according to claim 1, wherein said
shaft and barb elements are made of a body compatible material.
55. A bone anchoring element according to claim 54, wherein said
body compatible material comprises stainless steel, titanium
alloys, nickel-titanium alloys, nitinol, chrome alloy, cobalt
chrome alloys, shape memory alloys, materials with super elastic
properties, carbon reinforced composites, silicone, polyurethane,
polyester, polyether, polyalkene, polyethylene, polyamide,
poly(vinyl) fluoride, polyetheretherketone (PEEK), or
polytetrafluoroethylene (PTFE).
56. A bone anchoring element according to claim 54, wherein said
body compatible material comprises a bioabsorbable material.
57. (canceled)
58. A bone anchoring element according to claim 54 wherein said
body compatible material is coated with a bioactive material.
59. (canceled)
60. A bone anchoring element according to claim 54, wherein said
body compatible material has a microtexture.
61. A bone anchoring element according to claim 54, wherein said
shaft and barb elements are made of different body compatible
materials.
62-71. (canceled)
Description
REFERENCE TO EARLIER FILED APPLICATIONS
[0001] The present application claims the benefit of the filing
date under 35 U.S.C. .sctn. 119(e) of Provisional U.S. Patent
Application Ser. No. 60/547,517, filed Feb. 24, 2004, which is
hereby incorporated by reference. The present application also
claims foreign priority benefits pursuant to 35 U.S.C. .sctn. 119
(a)-(d) for German Patent Application 10 2004 009 429.2, filed Feb.
24, 2004 in Germany.
BACKGROUND
[0002] The present invention relates to a bone anchoring
element.
[0003] A known form of a bone anchoring element is a bone screw
comprising a shaft with a thread for screwing the screw into a
bone. The bone screw is manually inserted into the bone by means of
a screw driver, which is a time-consuming and force-requiring
process. Moreover, during the process in which the screw is
inserted into the bone, high pressure forces may be acting on the
bone itself, which is undesirable in some cases. For this reason,
manually inserted bone screws are not used for certain clinical
applications in neurosurgery, spinal surgery, pediatric surgery or
trauma surgery.
[0004] It is therefore desirable to provide a bone anchoring
element, which can be inserted into the bone more rapidly, more
easily, and with less force than conventional bone screws. It is
also desirable to provide a bone anchoring element that is
versatile and useful in many clinical requirements. Preferably the
bone anchoring element does not exert damaging forces on the bone,
provides for secure attachment, and yet still can be inserted more
deeply than conventional bone screws and/or removed in a screw-like
fashion.
[0005] EP 0 714 643 A1 discloses a bone fixation device such as a
screw, pin, staple, cable or anchor which has a micro-textured
contact surface to enhance installation or gripping characteristics
of the device. The micro-textured contact surface includes for
example, angled rasp teeth, which bite or flex to resist movement
in one direction and yet flex or slide to allow a relatively easy
contact movement in the other direction. DE 198 01 219 A1 discloses
a bone nail having rigid barb-like projections being arranged in
circumferential rows around the nail.
BRIEF SUMMARY
[0006] The present invention is directed to a hone anchoring
element that facilitates the rapid and secure anchoring to the bone
by pressing the bone anchoring element into a prepared core hole in
the bone. Barb elements are arranged on at least one helical line
around the shaft axis of the bone anchoring element. The barb
elements provide for a thread-like function, which allows the bone
anchoring element to be positioned deeper into the bone by means of
a screwing-in motion similar to that used with bone screws.
Moreover, the barb elements prevent the bone anchoring element from
being pulled out or coming loose. In addition, the bone anchoring
element of the instant invention can be removed, if required, just
like a screw, by turning it in the opposite or counterclockwise
direction from which it was inserted.
[0007] In a modified version of the first embodiment of the bone
anchoring element, the barb elements of the bone anchoring element
are made of a body compatible alloy with shape memory and/or
super-elastic properties.
[0008] In a second embodiment of the invention, a bone anchoring
element with a thread is provided as well as method of forming the
thread into the actual bone anchoring element.
[0009] The foregoing paragraphs have been provided by way of
general introduction, and are not intended to limit the scope of
the following claims. The presently preferred embodiments, together
with further advantages, will be best understood by reference to
the following detailed description taken in conjunction with the
accompanying drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
[0010] FIG. 1 shows a perspective view of a bone anchoring element
according to a first embodiment;
[0011] FIG. 2 shows a perspective exploded view of the bone
anchoring element according to FIG. 1;
[0012] FIG. 3 shows a sectional view of the bone anchoring element
according to FIG. 1, along the line, III-III;
[0013] FIG. 4 shows an magnified perspective exploded view of a
detail of the bone anchoring element according to FIG. 1;
[0014] FIG. 5 shows a perspective view of an element of the bone
anchoring element having a plate with barb elements according to
FIGS. 1 to 4 in a collapsed state;
[0015] FIG. 6 shows a perspective view of the bone anchoring
element having a plate with barb elements according to FIG. 5 in an
expanded state;
[0016] FIG. 7 shows a sectional view of the bone anchoring element
according to FIG. 6, along the line, II-II, in FIG. 6;
[0017] FIG. 8a) shows a schematic view of a first step of the
insertion of the bone anchoring element according to FIGS. 1 to
7;
[0018] FIG. 8b) shows a schematic view of a bone anchoring element
according to FIGS. 1 to 7 in the inserted state;
[0019] FIG. 9a) shows a schematic view of a first step of the
insertion of a modified bone anchoring element according to FIGS. 1
to 7;
[0020] FIG. 9b) shows a schematic view of a second step of the
insertion of the modified bone anchoring element;
[0021] FIG. 10 shows a schematic view of a bone anchoring element
according to another modification of the first embodiment;
[0022] FIG. 11a) shows a sectional view of the bone anchoring
element according to FIG. 10, along the line, IV-IV;
[0023] FIG. 11b) shows another different cross-sectional view of
the bone anchoring element described in FIG. 10, along the line,
IV-IV;
[0024] FIG. 11c) shows yet another different cross-sectional view
of the bone anchoring element described in FIG. 10, along the line,
IV-IV;
[0025] FIG. 12 shows a perspective view of a bone anchoring element
according to another modification of the first embodiment.
[0026] FIGS. 13a) to 13c) shows a bone anchoring element according
to a second embodiment at different stages of the manufacture of a
bone anchoring element according to a second embodiment;
[0027] FIG. 14 shows a view of a longitudinal cross-sectional view
of the second embodiment after the final manufacturing step shown
in FIG. 13c);
[0028] FIG. 15 shows a cross-sectional view through the shaft of
the bone anchoring element according to FIG. 13c) of the second
embodiment;
[0029] FIG. 16 shows an example of the application of the bone
anchoring element in the form of a monoaxial screw;
[0030] FIG. 17 shows an example of the application of the bone
anchoring element in the form of a polyaxial screw;
[0031] FIG. 18 shows an example of the application of the bone
anchoring element in conjunction with a fusion element and a plate
anchored in the vertebrae;
[0032] FIG. 19 shows an example of the application of the bone
anchoring element in the form of a intramedullary nail;
[0033] FIGS. 20-21 show an example of the application of the bone
anchoring element in conjunction with a plate to fix a bone
fracture;
[0034] FIG. 22 shows an example of the application of the bone
anchoring element in the hip;
[0035] FIG. 23 shows an example of the application of the bone
anchoring element in the ankle.
DETAILED DESCRIPTION OF THE DRAWINGS AND PRESENTLY PREFERRED
EMBODIMENTS
[0036] The invention and various embodiments thereof are presented
in FIGS. 1 to 23 and the accompanying descriptions wherein like
numbered items are identical.
[0037] A bone anchoring element according to a first embodiment of
the invention is described with reference to FIGS. 1 to 7. The bone
anchoring element, 1, comprises a shaft, 2, with a tip, 3, at one
end, and a head, 4, at the other end. The shaft, 2, is cylindrical
in shape and comprises a plurality of grooves, 5, 5' which extend
parallel to a shaft axis M. The plurality of grooves, 5, 5', are
open at their end facing the tip 3, and are closed, preferably in a
rounded fashion, at their end facing head 4. Although the grooves,
5, 5', shown in FIG. 3 have a dovetail-shaped profile, the profile
can also be of any other shape, such as for example a T shape. In
addition, the closed end of the groove can be any other shape
desired. In the example shown in FIG. 3, three grooves 5 are
provided at equal distances along the direction of the
circumference of shaft 2. However, any number of grooves desired
can be used provided that the grooves fit around the circumference
of the shaft. Therefore, at least two, three or more than three
grooves can be provided along the circumference of the shaft 2.
[0038] Plates 6, 6'with a cross-section matching that of grooves 5
are inserted into grooves 5 in a sliding fashion and are held
therein in a fitting or mating fashion. Preferably the plates are
oblong in shape and made of a body-compatible metal. However, the
plates can be made of other types of body-compatible materials in
other shapes provided that the plates abut the shaft and rest in
the grooves 5 in a fitting or mating fashion.
[0039] The plates, 6, each include a plurality of barb elements 7.
As is best seen in FIGS. 5 to 7, barb elements 7 are formed by
essentially trapezoidal shaped cuts 8 being made in the plates 6.
The end base 9 of the trapezoidal shaped cuts 8 is not cut-out from
the plate and acts as the attachment and the bending site for barb
elements 7 in the plate 6, 6'. Barb elements 7 are preferably
arranged such that when the plates are inserted into grooves 5, the
wider end base, 9, of the barb element faces the tip 3 while the
narrower free ends, or the cutting edges, 10, of barb elements 7
face the head 4.
[0040] As can be seen from FIGS. 5 to 7, barb elements 7 project
from the surface by a predetermined angle .gamma. which is selected
during the manufacturing process based upon the material used and
the actual dimensions of barb elements 7 so that a desired
stiffness of the barb element is obtained. Due to their
configuration and attachment, onto the plate, barb elements 7 are
elastically deformable relative to the body of the shaft. When the
barb elements 7 are collapsed or pressed into cuts 8, they are
pre-tensioned.
[0041] As is evident from FIG. 1, barb elements 7 of one plate 6
are arranged relative to barb elements 7 of a neighboring plate 6'
in axial direction on at least one helical line S around shaft axis
M. While a single continuous helical line S is illustrated, plural
parallel helical lines can also be used. Furthermore, the distances
between the barb elements can be varied along the length of the
shaft of the bone anchoring element as desired.
[0042] Moreover, as is further seen in the magnified representation
according to FIG. 4, the essentially trapezoidal-shaped cuts, 8,
are inclined with regard to the circular circumference line, U, by
an angle, .alpha., which corresponds to the helical angle of
helical line S. The free ends, 10, of the barb elements are thus
positioned on helical line S such that they form cutting edges
similar to the crest of a screw thread.
[0043] As is further evident from FIGS. 1 and 2, the embodiment
shown is provided with an area close to the head in each turn of
imaginary helical line S with a barb element, 7, and with an area
adjacent to tip 3 in every other turn with a barb element.
[0044] Furthermore, as seen in FIG. 2, tip 3 also has a smaller
diameter than shaft 2 in a section that is adjacent to the end of
the shaft 2 in order to facilitate the insertion of plates 6 into
the grooves 5. In the assembled state, wherein the plates 6, have
been inserted into grooves 5 by sliding the plates into the
grooves, a ring-shaped securing element 12 is also provided to
prevent the plates from sliding out of the groove. The ring-shaped
securing element 12 has a first end and a second end which tapers
in a cone-shaped section in the direction of tip 3 and connects
flush to the tip. The first end of the ring shaped securing element
abuts with the shaft 2 as well as plates to prevent the plates 6
from sliding out of the grooves. Securing element 12 is firmly
attached to the tip. Preferably the securing element is welded onto
the shaft. Other means of attachment are possible.
[0045] In the first embodiment, the head 4 of the bone anchoring
element is a spherically shaped segment. The head 4 has a recess
13, on its side facing away from the tip of the shaft. The recess
13 can be used during insertion of the bone anchoring element for
engagement of a screwing-in tool, such as a screw driver.
[0046] The bone anchoring element can be made of any
body-compatible material. Preferably a body-compatible metal, such
as for instance titanium, or a body-compatible plastic material can
be used. Examples of other body-compatible materials include
stainless steel, titanium alloys, nickel-titanium alloys, nitinol,
chrome alloy, cobalt chrome alloys, shape memory alloys, materials
with super elastic properties, carbon reinforced composites,
silicone, polyurethane, polyester, polyether, polyalkene,
polyethylene, polyamide, poly(vinyl) fluoride, polyetheretherketone
(PEEK), polytetrafluoroethylene (PTFE). In addition, the bone
anchoring element can be made of shape memory materials or alloys,
such as nickel titanium or nitinol. Furthermore, the bone anchoring
element can possibly be made from a bioabsorbable material.
Examples of bioabsorbable materials include polylactides, and
polyanhydrides. Plates 6 are made of the same material as the shaft
or of a different material if a different material is desired to
ensure that the barb elements 7 an the plates have the necessary
elastic properties. The securing element can be of any
biocompatible material.
[0047] The entire bone anchoring element or only the shaft and/or
the plates can be coated with a bioactive material such as for
example growth factors for bone ingrowth and bony attachment, or
for soft tissue ingrowth. Non-limiting examples of growth factors
include insulin-like growth factor 1, basic fibroblast growth
factor, transforming growth factor, platelet-derived growth factor,
bone-derived growth factors, arginine, bone morphogenetic protein,
LIM mineralization protein, and combinations thereof. The bioactive
material can facilitates in healing.
[0048] Furthermore, the entire bone anchoring element or only the
shaft and/or plates can be roughened to provide a texture on their
surfaces. The texture can be a microtexture in the form of bumps,
pyramids, rods, and so forth. The texture can be applied by
processes known in art. The roughened texture provides improved
anchoring of the screw to the bone.
[0049] In operation, the anchoring element, 1, is initially
preassembled by inserting the pre-made plates 6, 6', which are
already provided with barb elements 7, into grooves 5, 5' followed
by firmly connecting the securing element, 12, to the tip of the
shaft. In use, as is shown schematically in FIGS. 8a) and 8b), a
core hole, 14, is prepared first in the bone, 15. The diameter of
the core hole corresponds essentially to the diameter of shaft 2 or
it can be slightly larger or smaller, depending upon the desired
result or circumstances. The diameter of the core hole 14 is
selected depending on the diameter of the shaft 2 and the
flexibility of the barb elements so that the desired resistance is
provided by the barb elements. The selected diameter depends also
upon the bone quality, for example it can be selected larger for
healthy hard bone and smaller for osteoporotic weak bone
Subsequently, as shown in FIG. 8a), the bone anchoring element, 1,
is inserted into core hole 14. As the bone anchoring element is
being inserted into the core hole 14 of bone 15, the barb elements
7 are in a collapsed state and are pressed against or into the
cuts, 8, due to their elasticity, The sliding motion enables the
bone anchoring element to be inserted very rapidly, in contrast to
the conventional bone screws using the screwing-in process. When
inserted, the pre-tensioned barb elements, 7, expand and rise up
and press with their cutting edge, 10, outwardly against the wall
of core hole 14, as is evident from FIG. 8b). The barb elements
prevent the bone anchoring element from being pulled out or from
falling out of the core hole 14.
[0050] For further and/or final positioning of the bone anchoring
element in the core hole 14, or for positioning of the head, 4, the
bone anchoring element is screwed further into core hole 14 or
screwed out there from, like a screw, by means of a turning motion
with a screwing-in tool engaging the recess 13 in the head 4.
During the process, the cutting edges, 10, of the barb elements,
being positioned on helical line S, act like the crest of a thread.
The bone anchoring element can be removed just like a bone screw by
turning it in a counterclockwise direction.
[0051] In most cases, a conventional bone screw requires not only
that the core hole is drilled into the bone, but in also that the
bone threads are cut into the bone. In all cases with the insertion
of a conventional bone screw, a repeated turning motion is
required. Compared to the time required to anchor a conventional
bone screw, the time required to insert the bone anchoring element
according to the instant invention is substantially shorter due to
the fact that the bone anchoring element slides or glides into the
core hole 14 without having to encounter the forces of the screw
thread on the core hole 14 and bone 15. Nonetheless, because of its
design and configuration, the bane anchoring element does not fall
out of the core hole 14.
[0052] A modification of the first embodiment and its operation are
shown in FIGS. 9a) and 9b). This embodiment differs from the first
embodiment in that at least plates 60 with barbs 70 consist of a
body-compatible alloy with shape memory and/or super-elastic
properties. An example of such an alloy is a titanium-nickel alloy,
preferably nitinol. For this embodiment, the plates 60 are
fabricated so that at a predetermined higher temperature, the barb
elements 70 expand and project outwards from the shaft, whereas at
a temperature that is lower relative to this predetermined higher
temperature, the barb elements 70 are collapsed and reside within
cuts 80. As seen in FIG. 9a), the bone anchoring element slides
into core hole 14, with the barb elements 70 collapsed and residing
within the cuts 80. Once the bone anchoring element slides in the
core hole, as is shown in FIG. 9b), a heating device such as a
heating cartridge P can be inserted into a coaxial bore hole, 16,
inside the bone anchoring element. The heating cartridge P can heat
the bone anchoring element to the predetermined temperature,
whereby the ensuing phase transition of the crystal structure of
the metal plates causes barb elements 70 to deploy and rise up and
press against the wall of core hole 14. The heating cartridge can
then be removed from the coaxial bore hole 16.
[0053] This modified embodiment provides the advantage that it
reduces the amount of force that is required to press the bone
anchoring element into core hole 14 and enables the adjustment of
the bone anchoring element to a desired depth by the sliding motion
during its insertion as long as barb elements 70 are in a collapsed
state and do not press against the wall of core hole 14. Due to the
presence of super-elastic alloy, barb elements 70 can show
approximately 8 percent to 10 percent of stretching compared to
approximately one percent stretching with conventional metals. The
higher elasticity of the barb elements in this embodiment
simplifies the handling and provides additional security in
anchoring the bone anchoring element in the bone.
[0054] Yet another modification of the first embodiment is shown in
FIGS. 10 and 11. In this embodiment, the anchoring bone element
comprises a coaxial bore hole, 16, as described with respect to the
previous embodiments, which extends from the free end of head 4 to
the end of shaft 2 in the center of the shaft. Coaxial bore hole 16
is connected to cuts 8 in the plates 6 by means of radial bore
holes 17 which extend in a radial direction from the coaxial bore
hole 16 to the outer circumference of the shaft.
[0055] FIG. 11 a) shows a cross-sectional view of the bone
anchoring element 1 of FIG. 10 along the line IV-IV having a first
shaft configuration. The shaft 2, as seen in FIGS. 11 b) and 11 c)
can also be made of different configurations. For example, the
shaft 2 can be made in a shape so as to provide the slat-like cross
section as seen in FIG. 11 b) or concave cross-section as seen in
FIG. 11 c).
[0056] In operation, following the insertion and positioning of the
bone anchoring element at its desired insertion depth, coaxial bore
hole 16 and radial bore holes 17, can be used to deliver to the
surrounding bone area either bone cement or any active ingredient,
such as a drug or growth-promoting substance. The bone cement can
be used for additional anchoring, with the cement exiting through
cuts 8 and hardening thereafter. The number of the radial bore
holes, 17, need not correspond to the number of cuts 8, and
therefore, there may be less radial bore holes 17 than cuts 8. In
addition, the central bore hole, 16, may extend through the tip 3
so that the cement or active ingredient in the central bore hole 16
can also exit from tip 3.
[0057] In yet another modification shown in FIG. 12, the radial
bore holes, 17, extending from the coaxial bore hole 16, do not
face trapezoidal shaped cuts 8 of plates 6 in the direction of the
circumference, but end in the wall sections, 18, of the coaxial
bore hole 16, in which no plates 6 are provided.
[0058] FIGS. 13a) to 13c) show a second embodiment of the instant
invention at various stages of its manufacture and the steps of the
manufacturing process. FIG. 14 shows a cross-section in the
longitudinal direction of the bone anchoring element shown in FIG.
13c) after the final manufacturing step. FIG. 15 shows a
cross-sectional view of the shaft of the bone anchoring element
along line I-I according to the second embodiment shown in FIG.
13c.
[0059] As is seen from FIG. 13a), the first step of the
manufacturing process of the second embodiment of the bone
anchoring element 100 provides an bone anchoring element with a
shaft, 20, a tip, 30, on one end of the shaft, and a head, 40, at
the opposite end. In the second step of the manufacturing process
shown in FIG. 13b), a thread. 50, is cut into shaft 20. In the next
step, an undercut is generated in the thread 50 so that a partial
flank, 51, facing head 40 and the partial flank, 52, facing tip 30
include an angle of only several degrees, as is seen in FIG. 13c).
Preferably, the angle is between approximately 30.degree. to
60.degree.. The threads of this embodiment generate a certain
degree of elasticity and act as barb elements. FIG. 13c), shows
that sections 53 in the longitudinal direction of the shaft 20 are
subsequently milled. Preferably the sections 53 are concave in
shape towards the middle axis of the shaft and extend along the
entire length of the shaft. At least two, but preferably more,
sections 53 with equal mutual distances in the direction of the
circumference are thus provided. In conjunction with the remaining
thread parts with undercuts, this configuration generates barb
elements 57 that are similar to barb elements 7 of the first
embodiment.
[0060] The bone anchoring element according to this second
embodiment is preferably made from a body-compatible plastic
material, such as for example but not limited to a high-molecular
polyethylene. Using a body-compatible plastic material for this
embodiment is the easiest way to impart the necessary elasticity
required of barb elements 57.
[0061] Additional modifications of the described embodiments are
possible and elements of the individual embodiments and
modifications thereof may be combined with each other.
[0062] For example, in another modification, the anchoring element,
100, according to the second embodiment can also have a coaxial
bore hole and bore holes extending radially there from in the wall
for the insertion of an active substances.
[0063] Furthermore, with any of these various embodiments or
modifications, the barb elements need not be trapezoidal in shape.
Rather the barb elements can be of any shape which imparts the
desired characteristics to the barb element, including its
elasticity, such as for example but not limited a square, or
rectangular.
[0064] Unlike in the embodiment shown in FIG. 1, the barb elements
of an axial row may be provided at equal distances in axial
direction such that a barb element is present at that site of each
helix. Alternatively, the distances between the barb elements of a
row may vary in axial direction, whereby the distance in each case
corresponds to a an integral multiple of a smallest distance
between two barb elements of an axial row. Varying distances can be
used to account for differences in bone density and to reduce the
load on certain bone structures.
[0065] In yet another modification of the invention, the barb
elements are made from a shape memory alloy such that they project
at body temperature and are in a collapsed position at a lower
temperature, e.g. at room temperature. In operation of the bone
anchoring element made from a shape memory alloy, the bone
anchoring element with collapsed barb elements is pressed into the
core bore hole. After the bone anchoring element warms up and
equilibrates to body temperature, the barb elements expand to their
final position.
[0066] It is also possible to use a metal with correspondingly high
elasticity as the material for the bone anchoring element according
to the first embodiment or the plates with the barb elements or
even the single-piece screw according to the second embodiment.
[0067] Moreover, an absorbable material can be used for the bone
anchoring element. Plastic materials that are absorbable in the
body like polylactide (PLLA).
[0068] In another modification, the tip, 3, may be provided as a
separate piece which is connected to the shaft. For example, the
tip 3 can be screwed to shaft 2. In this embodiment, the end of the
shaft 2 facing the tip has a bore hole with internal thread whereas
the tip has a section with external thread that can be screwed into
the internal thread of the bore hole of the shaft. The tip can be
connected to the shaft with other known connectors.
[0069] FIG. 16 shows a first application example, in which two
vertebrae 90, 91 are made more stiff and rigid, through the use of
a fusion element, 92. Monoaxial bone anchoring elements 93, 94 are
provided by means of which a rod, 95, is anchored in the vertebra.
The monoaxial bone anchoring elements, 93, 94 each comprise a
shaft, 96, with a tip, 97, with the shaft being provided according
to one of the embodiments of the bone anchoring element described
above. At the end of shaft 96 that is opposite to tip 97, a
receiver member, 98, is provided which is rigidly connected to the
shaft and in which rod 95 is inserted in known fashion and secured
by means of a fixation element, 99, for instance by means of a nut
screwed onto the receiver member. In the case of the monoaxial bone
anchoring element, it is advantageous to provide shaft 96 with the
plates having barb elements made from the shape memory alloy, since
the bone anchoring element, after it is pressed into the core hole
bore and before it is heated, is capable of pivoting inside the
core hole bore allowing the alignment of receiver member 98
relative to the rod.
[0070] FIG. 17 shows yet another application example of this
invention. This example, differs from the application example
according to FIG. 16 in that polyaxial bone anchoring elements are
provided in place of the monoaxial bone anchoring elements. The
polyaxial bone anchoring elements, 93', 94', comprise a shaft, 96,
with a tip, 97, whereby shaft 96 is provided according to one of
the embodiments of the anchoring element with barb elements
according to the instant invention. At the end of shaft 96 that is
opposite from tip 97, a head, 101, is provided which, in the
non-fixed state, is held in a pivoting fashion in receiver member
98'. A rod, 95, can be placed in the receiver member in known
fashion, with rod 95 pressing either directly (not shown) or by
means of pressure member 102 (shown) onto head 101 thus effectively
fixing the pivoting position of the head relative to the receiver
member.
[0071] FIG. 18 shows as another application example, in which two
vertebral bones 90, 91 are stabilized and made more rigid after
removal of a portion between the vertebrae through the use of a
fusion element, 92', and a plate, 103, which is anchored in the
vertebrae by means of bone anchoring elements, 104, 105. The bone
anchoring elements 104, 105 comprise a shaft with barb elements
according to the invention and a head which is used to press plate
103 against the vertebral bone. The bone anchoring element can also
be used in conjunction with plates that are in use in trauma
surgery as shown by this example.
[0072] FIG. 19 shows as another application example of the instant
invention. In this example, an intramedullary nail, 106, comprises
a shaft and a tip, 107. Adjacent to the tip, the shaft of the nail
comprises a section, 108, which has barb elements like the bone
anchoring element according to the invention. The intramedullary
nail is inserted into a tubular bone and secured by means of a
screw, 109.
[0073] FIG. 20 shows another application example, in which the bone
anchoring element is used in conjunction with a plate, 110, to fix
a bone fracture. Adjacent to tip 3, the bone anchoring element
comprises a first shaft section, 111, which contains the barb
elements, and adjacent to this first shaft section a second shaft
section, 112, with a pocket hole bore, 113, with an internal
thread, said pocket hole bore 113 extending from the end opposite
to tip 3 towards the inside. A screw 114 is used to connect the
bone anchoring element with plate 110. Screw, 114, can be screwed
into the section of the bone anchoring element with an internal
thread. In operation, the core hole bore is generated first in bone
fragments 115, 116 to be fixed, followed by the insertion of the
bone anchoring element. Here, the length of the core hole bore is
such that section 111 with the barb elements and tip 3 of the
anchoring element can be positioned in the one bone fragment, 116,
and shaft section 112 with the internal thread can be positioned in
the other bone fragment, 115. When screw 114 is screwed into bore
hole 113 with the internal thread, the barb function of section
111, which is positioned in the one bone fragment, 116, causes the
two bone fragments, 115, 116, to be pulled towards each other.
Other screws, 117, may be provided for fixation of the plate.
[0074] Another application example of the instant can be found in
FIG. 21. The example shown in FIG. 21 differs from the application
example of the bone anchoring element shown in FIG. 20 in that, in
place of shaft section 112 with bore hole 113 having an internal
thread, a shaft section, 118, with an external thread is provided
adjacent to section 111 with the barb elements, onto which a
external thread a nut, 119, can be screwed. The operation is
identical to the application example shown in FIG. 20 with the
exception that nut 119 is screwed on screw 114 instead of being
screwed in.
[0075] FIG. 22 shows another application example of the bone
anchoring element of FIG. 21 as used in a hip joint to fix a hip
fracture in conjunction with a supporting plate. One side of the
plate is attached to the bone by a screw described in the second
embodiment of this invention or with a conventional bone screw. The
other side of the plate is attached by a screw described in FIG.
21. Similarly, FIG. 23 shows the bone anchoring element of FIG. 21
being used in an ankle to fix an ankle injury.
[0076] The embodiments described above and shown herein are
illustrative and not restrictive. The scope of the invention is
indicated by the claims, including all equivalents, rather than by
the foregoing description and attached drawings. The invention may
be embodied in other specific forms without departing from the
spirit and scope of the invention. Accordingly, these and any other
changes which come within the scope of the claims are intended to
he embraced therein.
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