U.S. patent application number 12/148678 was filed with the patent office on 2008-10-30 for device and method for preparing a recess in a bone.
This patent application is currently assigned to Stryker Trauma GmbH. Invention is credited to Klaus Dorawa.
Application Number | 20080269649 12/148678 |
Document ID | / |
Family ID | 39684365 |
Filed Date | 2008-10-30 |
United States Patent
Application |
20080269649 |
Kind Code |
A1 |
Dorawa; Klaus |
October 30, 2008 |
Device and method for preparing a recess in a bone
Abstract
A punching device for preparing a recess in a bone has a
punching tool usable for such a punching device. An implant usable
with the punching tool is provided and a method for preparing a
recess in a bone are disclosed. The punching device comprises an
ultrasonic sonotrode and a punching tool which is fixable to the
sonotrode at its proximal extremity. At its distal extremity, the
punching tool has a thin-walled portion having a non-rotational
symmetric cross-section. By ultrasonic vibration of the punching
tool, the thin-walled portion can be forced into a bone thereby
preparing a recess of which is not rotationally symmetric.
Subsequently, an implant can be held in such recess. Due to its
lack of rotational symmetry, the implant may absorb rotational
forces around its longitudinal axis.
Inventors: |
Dorawa; Klaus;
(Schonkirchen, DE) |
Correspondence
Address: |
LERNER, DAVID, LITTENBERG,;KRUMHOLZ & MENTLIK
600 SOUTH AVENUE WEST
WESTFIELD
NJ
07090
US
|
Assignee: |
Stryker Trauma GmbH
Schonkirchen
DE
|
Family ID: |
39684365 |
Appl. No.: |
12/148678 |
Filed: |
April 21, 2008 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
60926884 |
Apr 30, 2007 |
|
|
|
Current U.S.
Class: |
601/2 ;
606/184 |
Current CPC
Class: |
A61B 17/1604 20130101;
A61B 17/864 20130101; A61B 10/025 20130101; A61B 17/32053 20130101;
A61B 2017/00371 20130101; A61B 2017/00004 20130101; A61B 17/8894
20130101 |
Class at
Publication: |
601/2 ;
606/184 |
International
Class: |
A61H 1/00 20060101
A61H001/00; A61B 17/14 20060101 A61B017/14 |
Claims
1. A punching device for preparing a recess in a bone, the punching
device comprising: an ultrasonic sonotrode, a punching tool being
fixable to the sonotrode at its proximal extremity, wherein, at its
distal extremity, the punching tool has a thin-walled portion
having a cross section not being rotationally symmetric.
2. The punching device according claim 1, wherein the thin-walled
portion has a wall thickness (t) of less than 2 mm.
3. The punching device according to claim 1, wherein the
thin-walled portion has an annular cross section.
4. The punching device according to claim 1, wherein the
thin-walled portion has a non-symmetric cross section.
5. The punching device according to claim 1, wherein the punching
tool comprises a bio-compatible material.
6. The punching device according to claim 1, wherein the punching
tool comprises a bio-resorbable material.
7. The punching device according to claim 1, wherein the
thin-walled portion has a lateral surface providing a high surface
friction.
8. The punching device according to claim 1, further comprising an
ultrasonic generator.
9. The punching device according to claim 8, wherein the ultrasonic
generator is adapted to excite the punching tool with a vibration
frequency of between 10 kHz and 100 kHz.
10. The punching device according to claim 8, wherein the
ultrasonic generator is adapted to excite the punching tool with a
vibration amplitude of between 1 .mu.m and 300 .mu.m.
11. A punching tool usable for preparing a recess in a bone,
wherein the punching tool is adapted to be used in a punching
device according to claim 1.
12. An implant to be inserted into a bone, wherein the implant is
adapted to be used as a punching tool for a punching device
according to claim 1.
13. A method for preparing a recess in a bone, the method
comprising: providing a punching device according to claim 1;
abutting the punching tool on the bone; vibrating the punching tool
with ultrasonic vibrations and pushing the punching tool into the
bone.
14. The method of claim 13, further comprising: removing the
punching tool from the bone.
15. The method of claim 13, further comprising: releasing the
punching tool from the sonotrode.
Description
CROSS REFERENCE TO RELATED APPLICATION
[0001] This application claims the benefit of the filing date of
U.S. Provisional Patent Application No. 60/926,884 filed Apr. 30,
2007, the disclosure of which is hereby incorporated herein by
reference.
BACKGROUND OF THE INVENTION
[0002] The invention relates to preparing recesses or holes in
bones of humans or animals. In such recesses or holes implants e.g.
in the form of screws may be introduced. Such screws may be used
for example to treat fractures of bones.
[0003] Conventionally, the recesses were generally drilled with a
rotating tool and both the recesses and the screws or pins to be
inserted therein usually have a circular cross-section. Due to this
circular cross-section, a single recess-screw-combination is not
suitable to accommodate rotation forces applied around the axis of
the screw. In order to accommodate such rotation forces which may
occur for example when fixing two parts of bones together or when
fixing an implant to a bone, it has been necessary to provide a
plurality of screws or pins inserted into a plurality of recesses
prepared in the bone.
[0004] The necessity of preparing a plurality of recesses in a bone
for example during a surgical intervention requires additional work
for a physician. Furthermore, the preparation of a plurality of
recesses in a bone may increase the discomfort for a patient and
may delay the healing.
SUMMARY OF THE INVENTION
[0005] One aspect of the present invention is to provide a punching
device for preparing a recess in a bone, a punching tool adapted to
be used in such punching device or an implant adapted to be used as
a punching tool for such punching device. A method is also
disclosed for preparing a recess in a bone wherein the necessity of
preparing a plurality of recesses can be avoided when an
implantation device is to be inserted into a bone such that it can
accommodate rotational forces between it and the bone.
[0006] These needs may be met by a punching device, a punching
tool, an implant and a method for preparing a recess in a bone
according to punching device for preparing a recess in a bone. The
punching device comprises: an ultrasonic sonotrode, a punching tool
being fixable to the sonotrode at its proximal extremity, wherein,
at its distal extremity, the punching tool has a thin-walled
portion having a cross section not being rotationally symmetric.
The thin-walled portion preferably has a wall thickness (t) of less
than 2 mm and may have an annular cross section. The thin-walled
portion annular cross section may have a non-symmetric cross
section. The punching tool may be made of a bio-compatible or
bioabsorbable material. The punching device thin-walled portion can
have a lateral surface providing a high surface friction. An
ultrasonic generator is adapted to excite the punching tool with a
vibration frequency of between 10 kHz and 100 kHz and a vibration
amplitude of between 1 .mu.m and 300 .mu.m. A punching tool usable
for preparing a recess in a bone, wherein the punching tool is
adapted to be used in a punching device as described above. An
implant is inserted into a bone, wherein the implant is adapted to
be used as a punching tool for a punching device. A method is used
for preparing a recess in a bone, the method comprising: providing
a punching device; abutting the punching tool on the bone;
vibrating the punching tool with ultrasonic vibrations and pushing
the punching tool into the bone. The method includes the step of
removing the punching tool from the bone and releasing the punching
tool from the sonotrode.
[0007] According to an aspect of the present invention a punching
device for preparing a recess in a bone comprises an ultrasonic
sonotrode and a punching tool being fixable to the sonotrode at its
proximal extremity. Therein, the punching tool has a thin-walled
portion at its distal extremity.
[0008] In the following, further features, advantages and
embodiments of the punching device according to the first aspect
will be explained in detail.
[0009] An ultrasonic sonotrode is a mechanical component which is
adapted to transmit ultrasonic vibrations emitted by an ultrasonic
generator to a tool which may be fixed to the ultrasonic sonotrode.
For this purpose, the sonotrode can comprise a mechanism for
fixedly coupling the sonotrode to an ultrasonic generator and a
mechanism for coupling a tool to be vibrated to the sonotrode. In
another embodiment, the punching tool may be axially slidable in
relation to the ultrasonic sonotrode and the vibrating sonotrode
may "hammer" onto the tool.
[0010] The punching tool is adapted to be fixed to the sonotrode at
its proximal extremity. For example, the punching tool can be an
elongated member. It may have a sufficient rigidity to transmit
ultrasonic vibrations from its proximal extremity to its distal
extremity.
[0011] At its distal extremity, the punching tool has a thin-walled
portion. The thin-walled portion may be for example, a portion,
where, in the cross-section of the thin-walled portion, a dimension
in one direction of the thin-walled portion is substantially
larger, for example three times larger, preferably ten times
larger, than a dimension in a direction perpendicular thereto. The
thin-walled portion of the punching tool can have a linear or a
curved cross-section.
[0012] The thin-walled portion may have a non-rotational symmetric
cross-section, i.e. a cross-section having no rotational symmetry.
In other words, the two-dimensional geometry of the cross-section
of the thin-walled portion can not be described by rotation of any
one-dimensional pattern. Preferably, the cross-section is
non-round. Therein, the cross-section is taken in a plane normal to
the longitudinal axis of the punching tool.
[0013] The present invention is based on the idea that by using the
punching tool which is fixedly coupled to an ultrasonic sonotrode
which itself is coupled to an ultrasonic generator such that
ultrasonic vibrations can be transmitted to the distal extremity of
the punching tool, a recess of arbitrary circumferential geometry
can be created within a bone. For this purpose, as will be
described further below, the punching tool may be abutted against
the bone and the vibrating punching tool may be pushed into the
bone. Therein, the ultrasonic vibrations on the punching tool may
act as little hammer blows whereby the punching tool may be forced
into the bone. In order to generate a high pressure between the
punching tool and the bone, the punching tool has a thin-walled
portion such that the contact area between the punching tool and
the bone is kept small.
[0014] As the thin-walled portion of the punching tool has a
non-rotationally symmetric cross-section, the recess in the bone
prepared thereby will have a non-rotationally symmetric
cross-section. In such non-rotationally symmetric recess a
corresponding non-rotationally symmetric implant may be
press-fitted for positive fitting within the recess. As the implant
and the recess have non-rotationally symmetric cross-sections
rotational forces acting around the longitudinal axis of the
implant may be absorbed by the implant and it may not be necessary
to prepare a plurality of recesses in the bone in order to absorb
such rotational forces.
[0015] According to an embodiment of the invention the thin-walled
portion has a wall thickness of less than 2 mm, preferably less
than 1 mm and more preferred between 0.2 and 0.5 mm. The smaller
the thickness of the thin-walled portion the higher the pressure
which can be applied by the punching tool onto the bone. However,
the thickness of the thin-walled portion should be sufficient in
order to provide sufficient stability for the thin-walled portion
during preparing the recess in the bone such that the thin-walled
portion does not deform or deflect during the process of preparing
the recess and the vibration from the sonotrode is reliably
transmitted to the contact area between punching tool and bone.
[0016] According to a further embodiment of the present invention
the thin-walled portion has an annular cross-section. In other
words, the thin-walled portion may have a self-contained, ring-like
closed structure which, however, preferably should not have a
circular cross-section. For example, the thin-walled portion may
have the form of a hollow triangle, a hollow rectangle or any other
hollow polygon.
[0017] According to a further embodiment of the present invention
the thin-walled portion has a non-symmetric cross-section. This
lack of symmetry, i.e. lack of mirror symmetry or lack of point
symmetry or both, can be used to align an implant to be inserted
into the recess in a predetermined way. Accordingly, already when
preparing the recess in the bone an orientation of the implant to
be fitted therein may be predetermined.
[0018] According to another embodiment, the punching tool comprise
a metallic material. E.g. any kind of stainless steel, titanium
alloys, aluminium alloys such as Ti6Al4v, APX, 1.4057, 1.4442, etc
can be used. Bio-compatible metals are preferably used. Such
bio-compatible material can be used for the punching tool in order
to avoid interferences from occurring when punching a recess into a
bone.
[0019] According to a further embodiment, the punching tool
comprises a polymeric material. E.g. any kind of thermoplastic
material such as e.g. PEEK (Polyetheretherketone), UHMWPE (Ultra
high molecular weight polyethylene), and bioabsorbable materials
such as PLA (Polylactic acid), PLLA (Poly-L-lactide), PLDLA
(Poly(D,L-Lactid)), PDLLA (Poly-DL-lactide), PVDF (Polyvinylidene
Difluoride), PPSU or ABS may be used. Such punching tools made with
a bio-resorbable material can be used both for punching the recess
into the bone and later on as an implant to remain in the prepared
recess. Therein, after preparing the recess, the punching tool can
be released from the ultrasonic sonotrode. It can remain in the
prepared recess and after a predetermined period for healing, be
resorbed in the bone.
[0020] According to another embodiment, the thin-walled portion of
the punching tool has a lateral surface providing a high surface
friction. For example, in a thin-walled portion having an annular
cross-section it may be advantageous to provide the inner surface
of the thin-walled portion such that high surface friction is
obtained e.g. by providing this surface with a suitable surface
geometry such as for example an increased roughness or by providing
this surface with a material having a high coefficient of friction.
Using such punching tool the punching tool may be first forced into
the bone thereby preparing a recess in the form of the annular
cross-section. Subsequently, when withdrawing the punching tool
from the bone, the thin-walled portion having such high surface
friction on its inner surface may entrain the bone portion located
within the annular thin-walled portion, thereby preparing a
complete hole comprising both the annular cross-section and the
area therein. Accordingly, with such punching device a recess can
be prepared in a bone the cross-section of which is substantially
larger than the cross-section of the thin-walled portion of the
punching tool.
[0021] According to a further embodiment of the present invention,
the punching device further comprises an ultrasonic generator. This
ultrasonic generator may be suitably adapted to be coupled with the
ultrasonic sonotrode such that ultrasonic vibrations may be
transmitted from the generator to the sonotrode.
[0022] In a further embodiment the ultrasonic generator is adapted
to excite the punching tool with a vibration frequency of between
10 kHz and 100 kHz, preferably between 20 kHz and 40 kHz.
[0023] According to a further embodiment the ultrasonic generator
is adapted to excite the punching tool with a vibration amplitude
of between 1 .mu.m and 300 .mu.m, preferably between 5 .mu.m and
100 .mu.m. The vibration amplitude is defined in a direction
perpendicular to the initial contact surface between the
thin-walled portion of the punching tool and the bone, this being
usually a longitudinal direction of the punching tool. The
vibration amplitude might be selected taking into account the kind
of bone into which a recess is to be introduced. For example, in
weak bones a small vibration amplitude of e.g. 5 .mu.m might be
advantageous in order not to excessively stress such bones whereas
in strong bones a higher vibration amplitude of e.g. 100 .mu.m
might be advantageous as the recess can be prepared faster.
[0024] A further aspect of the present invention is directed to a
punching tool being usable for preparing a recess in a bone wherein
the punching tool is adapted to be used in a punching device
according to the first aspect described above.
[0025] Such a punching tool may be provided independently from the
ultrasonic sonotrode. However, the sonotrode and the punching tool
should be adapted such that they can be coupled together such that
ultrasonic vibrations can be transmitted from the sonotrode to the
punching tool. A plurality of punching tools having different
geometry in their thin-walled portions may be provided such that a
physician can choose a suitable punching tool during an operation
and also may release and replace a punching tool during an
operation.
[0026] In a further aspect of the invention an implant to be
inserted into a bone is provided wherein the implant is adapted to
be used as a punching tool for the inventive punching device as
described above. Such implant should satisfy two requirements: (a)
On the one hand it should be sufficiently rigid to be used as a
punching tool for preparing a recess in a bone; (b) on the other
hand it should have a suitable material and/or geometry in order to
be able to remain in the recess previously prepared therewith.
[0027] In a further aspect of the invention a method for preparing
a recess in a bone is provided, the method comprising: providing a
punching device according to the above first aspect; abutting the
punching tool of the punching device on the bone; vibrating the
punching tool with ultrasonic vibrations and pushing the punching
tool into the bone.
[0028] According to an embodiment, the punching tool can be removed
from the bone after preparing the recess. Thereby, a recess may be
prepared in the bone into which an implant can subsequently be
inserted.
[0029] According to another embodiment the punching tool may be
released from the sonotrode after pushing it into the bone and the
punching tool may remain in the prepared recess as an implant.
[0030] It has to be noted that embodiments of the invention are
described with reference to different subject-matters. In
particular, some embodiments are described with reference to
apparatus type claims whereas other embodiments are described with
reference to method type claims. However, a person skilled in the
art will gather from the above and the following description that,
unless other notified, in addition to any combination of features
belonging to one type of subject-matter also any combination
between features relating to the different subject-matters, in
particular between features of the apparatus type claims and
features of the method type claims, is considered to be disclosed
with this application.
[0031] The aspects defined above and further aspects, features and
advantages of the present invention can be derived from the
examples of embodiments described hereinafter.
[0032] The invention will be described in more detail hereinafter
with reference to examples of embodiments but to which the
invention is not limited.
BRIEF DESCRIPTION OF THE DRAWINGS
[0033] FIG. 1 schematically shows a punching device according to an
embodiment of the invention;
[0034] FIGS. 2a and 2b show embodiments of the punching device and
different uses thereof according to the invention; and
[0035] FIGS. 3a to 3e show different cross-sectional geometries of
the thin-walled portion of the punching tool according to
embodiments of the invention.
[0036] In the figures like reference signs designate like elements.
Furthermore, it is to be noted that the figures are not to
scale.
DETAILED DESCRIPTION
[0037] As schematically shown in FIG. 1, a punching device 1
according to an embodiment of the invention comprises an ultrasonic
generator 3 controlled via a control 5, an ultrasonic sonotrode 7
and a punching tool 9.
[0038] The ultrasonic sonotrode 7 is coupled to the ultrasonic
generator 3 via a fixation mechanism 11 which can comprise for
example a frame 13 and a clamping screw 15. The ultrasonic
generator 3 is adapted to emit ultrasonic vibrations with an
adaptable frequency of e.g. 20 to 50 kHz which are transmitted to
the sonotrode 7. The arrow A in FIG. 1 indicates a direction of
these ultrasonic vibrations. Furthermore, the ultrasonic generator
3 may be adapted to produce ultrasonic vibrations with a selectable
amplitude of between 5 and 100 .mu.m along the direction A.
[0039] The punching tool 9 is coupled to the ultrasonic sonotrode 7
via a further fixation mechanism 17 which can comprise a clamping
screw 19. Thereby, the ultrasonic vibrations can be transmitted
from the sonotrode to the punching tool. The punching tool 9
comprises at its proximal extremity a solid portion 21 and at its
distal extremity a thin-walled portion 23. The thin-walled portion
23 can have a non-round cross-section as will be described further
below with reference to FIGS. 3a to 3e.
[0040] When the punching tool being vibrated via the sonotrode is
pushed onto a bone 25, the thin-walled portion 23 exerts a
significant pressure onto the bone while being vibrated up and down
in a hammer-like manner. Due to this ultrasonic "hammering" the
thin-walled portion 23 of the punching tool 9 can be introduced
into the bone. In contrast to conventional drilling methods, there
is no rotating of the punching tool such that the recess which is
prepared by the punching device does not need to have a rotational
geometry.
[0041] FIGS. 2a and 2b show different embodiments of punching tools
usable for preparing recesses of different cross-sectional areas in
a bone. In FIG. 2a, the lateral surfaces 27, 29 of the thin-walled
portion of the punching tool 9 both have a low surface friction.
Accordingly, the punching tool 9 can be easily withdrawn from the
bone after preparing the recess in the bone. The recess itself then
has a cross-section which essentially corresponds to the
cross-section of the thin-walled portion. Accordingly, the portion
of an implant to be inserted into the recess should approximately
have the geometry as the thin-walled portion of the punching tool.
Alternatively, the punching tool itself can act as such implant and
can remain in the recess after preparing the recess.
[0042] Alternatively, as shown in FIG. 2b, the thin-walled portion
of the punching tool 9 can have a low surface friction on its outer
lateral surface 29 whereas it can have a high surface friction at
its inner lateral surface 27. Accordingly, after preparing the
recess in the bone by ultrasonic "hammering" the thin-walled
portion into the bone, when removing the punching tool from the
bone, a part of the bone lying between the inner lateral surfaces
27 of the thin-walled portion can be removed therewith due to the
high surface friction. Subsequently, a massive implant can be
press-fitted into the large-area recess.
[0043] In FIGS. 3a to 3e several possibilities for the
cross-section of the thin-walled portion of the punching tool are
schematically shown. FIG. 3a shows a triangular cross-section. FIG.
3b shows a rectangular cross-section. FIG. 3c shows a star-like
cross-section. FIG. 3d shows an arbitrary non-symmetric
cross-section. All of the cross-sections for the thin-walled
portion shown in FIGS. 3a to 3d include a closed annular
cross-section having an inner lateral surface 29 and an outer
lateral surface 27.
[0044] The cross-section shown in FIG. 3e is serpent-like and has
no annular cross-section. Furthermore, a wall thickness (t) of the
thin-walled portion is shown.
[0045] All of the cross-sections for the thin-walled portion of the
punching tools shown in FIGS. 3a to 3e have no rotational symmetry
and are therefore suitable to prepare a corresponding
non-rotationally symmetric recess in a bone in which an implant can
be inserted which then is able to absorb a rotational force around
the longitudinal axis of the punching device.
[0046] Summarizing, a punching device for preparing a recess in a
bone, a punching tool usable for such punching device 1, an implant
usable with such punching tool and a method for preparing a recess
in a bone are proposed. The punching device comprises an ultrasonic
sonotrode 7 and a punching tool 9 which is fixable to the sonotrode
at its proximal extremity. At its distal extremity, the punching
tool 9 has a thin-walled portion 23 having a rotationally
non-symmetric cross-section. By ultrasonic vibration of the
punching tool, the thin-walled portion can be forced into a bone
thereby preparing a recess which is not rotationally symmetric.
Subsequently, an implant can be held in such recess. Due to its
lack of rotational symmetry, the implant may absorb rotational
forces around its longitudinal axis.
[0047] It should be noted that the term "comprising" does not
exclude other elements or steps and the "a" or "one" does not
exclude a plurality. Also elements described in association with
different embodiments and aspects may be combined. It should also
be noted that reference signs in the claims shall not be construed
as limiting the scope of the claims.
[0048] Although the invention herein has been described with
reference to particular embodiments, it is to be understood that
these embodiments are merely illustrative of the principles and
applications of the present invention. It is therefore to be
understood that numerous modifications may be made to the
illustrative embodiments and that other arrangements may be devised
without departing from the spirit and scope of the present
invention as defined by the appended claims.
* * * * *