U.S. patent application number 13/075611 was filed with the patent office on 2011-10-06 for reaming device with carbon fiber shaft and molded interface element.
This patent application is currently assigned to STRYKER TRAUMA GMBH. Invention is credited to Helge Giersch, Ingo Stoltenberg.
Application Number | 20110245831 13/075611 |
Document ID | / |
Family ID | 42352225 |
Filed Date | 2011-10-06 |
United States Patent
Application |
20110245831 |
Kind Code |
A1 |
Giersch; Helge ; et
al. |
October 6, 2011 |
REAMING DEVICE WITH CARBON FIBER SHAFT AND MOLDED INTERFACE
ELEMENT
Abstract
A reaming device comprising a shaft with a mounting portion, the
mounting portion having an outer surface; a carbon fiber layer
located on the mounting portion outer surface; an injection molded
interface element for mechanical coupling of an external device
molded on the carbon fiber layer, the interface element having a
mounting portion; wherein the carbon fiber layer extends over the
outer surface of the shaft mounting portion and having an outer
surface, wherein the carbon fiber layer outer surface has a
non-smooth surface structure; wherein the injection molded
interface element mounting portion is injection molded over the
carbon fiber layer surface structure The method according to claim
12, further comprising preparing of shaft mounting portion before
wrapping a carbon fiber layer for establishing a reliable
connection between the shaft and the carbon fiber layer.
Inventors: |
Giersch; Helge; (Kiel,
DE) ; Stoltenberg; Ingo; (Probsteierhagen,
DE) |
Assignee: |
STRYKER TRAUMA GMBH
Schoenkirchen
DE
|
Family ID: |
42352225 |
Appl. No.: |
13/075611 |
Filed: |
March 30, 2011 |
Current U.S.
Class: |
606/80 ;
156/191 |
Current CPC
Class: |
A61B 17/164 20130101;
A61B 2090/037 20160201; A61B 17/162 20130101; B29C 45/14786
20130101; A61B 2017/00526 20130101 |
Class at
Publication: |
606/80 ;
156/191 |
International
Class: |
A61B 17/16 20060101
A61B017/16; B29C 70/68 20060101 B29C070/68 |
Foreign Application Data
Date |
Code |
Application Number |
Mar 31, 2010 |
EP |
10 158 573.5 |
Claims
1. A reaming device comprising a shaft with a mounting portion, the
mounting portion having an outer surface; a carbon fiber layer
located on the mounting portion outer surface; an injection molded
interface element for mechanical coupling of an external device
molded on the carbon fiber layer, the interface element having a
mounting portion; wherein the carbon fiber layer extends over the
outer surface of the shaft mounting portion and having an outer
surface, wherein the carbon fiber layer outer surface has a
non-smooth surface structure; wherein the injection molded
interface element mounting portion is injection molded over the
carbon fiber layer surface structure.
2. The reaming device according to claim 1, wherein the shaft is
made of a carbon fiber reinforced material.
3. The reaming device according to claim 1, wherein the carbon
fiber layer comprises a wrapped carbon fiber with a resin
impregnation.
4. The reaming device according to claim 1, wherein the carbon
fiber layer surface structure comprises a pressed tooth
structure.
5. The reaming device according to claim 4, wherein the pressed
tooth structure comprises an elongated rippled structure.
6. The reaming device according to claim 1, wherein the interface
element comprises a coupling portion for coupling a power tool
reamer drive as an external device.
7. The reaming device according to claim 6, wherein the coupling
portion comprises an end portion being capable of transmitting a
torque.
8. The reaming device according to claim 6, wherein the injection
molded interface element comprises a rated break section between
its mounting portion and its coupling portion.
9. The reaming device according to claim 1, wherein the injection
molded interface element comprises a mold material having shape
stability at common sterilization temperatures.
10. The reaming device according to claim 1, wherein the injection
molded interface element comprises a deformation indicating pattern
indicating a pre-breaking deformation.
11. The reaming device according to claim 1, wherein both, the
shaft and the interface element each have an elongated through
bore, the both through bores aligning to each other.
12. A method for manufacturing a reaming device, comprising:
wrapping a carbon fiber layer over an outer surface of a mounting
portion of a shaft; and pressing a surface structure on an outer
surface of the carbon fiber layer; injection molding an interface
element over the surface structure.
13. The method according to claim 12, wherein wrapping comprises
impregnating the carbon fiber layer with an impregnation agent
being compatible with a material of the shaft.
14. The method according to claim 12, further comprising preparing
of shaft mounting portion before wrapping a carbon fiber layer for
establishing a reliable connection between the shaft and the carbon
fiber layer.
15. The method according to claim 12, wherein pressing includes
heat setting of the carbon fiber layer in a closed mold.
Description
CROSS REFERENCE TO RELATED APPLICATION
[0001] The present application claims priority from European Patent
Application No. 10158573.5 filed Mar. 31, 2010, which is
incorporated herein by reference
BACKGROUND OF THE INVENTION
[0002] The present invention relates to a reaming device, and in
particular to a reaming device providing a reliable connection
between a carbon fiber composite shaft and an interface element
molded thereon.
[0003] Intramedullary nailing is the method of choice for the
fixation of fractures in long bones, in particular bones in long
extremities. To have full access to the intramedullary channel, a
shaft of a reamer has to be flexible enough in a bending direction
to bypass soft tissue and conform to bone curvature. The shaft also
has to be rigid enough to convey torsion to the reamer head. Prior
art reaming devices have a shaft design consisting of a helix in
which residues can be trapped during the reaming procedure, so that
the cleaning of the reaming device in hospitals prior to the next
usage is complicated, in particular in a sterilization process. The
adequate cleaning of the instrument in hospitals demands a great
effort and takes a lot of time. Further, some hospitals are not
prepared to clean such critical devices because of the great effort
involved.
[0004] In some prior art reaming devices, a helix shaft is replaced
by a shaft made of so called nitinol, which is a material having a
high degree of elasticity (super elasticity) to provide enough
flexibility. Nitinol is an acronym for NIckel TItanium Naval
Ordnance Laboratory. Nitinol is the inter-metallic phase NiTi
having a regular cubic crystal structure being different of the
structure of titanium or nickel. Nitinol comprises about 55% nickel
and about 45% titanium. Owing to the fact that the nitinol shaft is
made of a single tube, the cleaning effort in the hospital is less
exhausting. However, recent investigations have shown that the
nitinol material has a catastrophic failure mode. In particular,
some reports have pointed out that some breakages in multiple
fragments of the nitinol shaft occurred during the reaming process
during the intervention process in hospitals. Further, the nitinol
material is a very expensive material.
[0005] EP 253526 and U.S. Pat. No. 4,751,922 relates to a shaft
made of a composite material of filamentous fibers and an
appropriate resin.
[0006] From US 2007/0015107, a root canal instrument having an
abrasive coating and method for the production thereof is known,
wherein the described root canal instrument has a core of a
flexible elastic material having a shape memory, wherein the core
furthermore has a coating with abrasive particles, wherein the core
is made from a nickel-titanium alloy or from a plastic material,
e.g. carbon fibre reinforced plastics material.
[0007] CH 668690 relates to a probe electrode cable for medical
purposes, e.g. electro cardiogram test, using carbon fibre
impregnated plastic insulating coating as a cover with a lead
coupled to the test equipment.
[0008] US Patent Publication No. 2010/0239380 relates to a reaming
device with a carbon fiber shaft, an interface element and a
connecting agent. The disclosure of 2010/0239380 is incorporated
herein by reference.
BRIEF SUMMARY OF THE INVENTION
[0009] It is one aspect of the present invention to provide a more
reliable reaming device.
[0010] One aspect of the present invention is solved by a reaming
device comprising a shaft with a mounting portion, the mounting
portion having an outer surface. A carbon fiber layer located on
the mounting portion outer surface. An injection molded interface
element for mechanical coupling of an external device molded on the
carbon fiber layer, the interface element having a mounting
portion. The carbon fiber layer extends over the outer surface of
the shaft mounting portion and has an outer surface. The carbon
fiber layer outer surface has a non-smooth surface structure. The
injection molded interface element mounting portion is injection
molded over the carbon fiber layer surface structure. The shaft of
the reaming device is made of a carbon fiber reinforced material.
The carbon fiber layer comprises a wrapped carbon fiber with a
resin impregnation. The carbon fiber layer surface structure
comprises a pressed tooth structure. The pressed tooth structure
comprises an elongated rippled structure. The interface element
comprises a coupling portion for coupling a power tool reamer drive
as an external device. The coupling portion comprises an end
portion being capable of transmitting a torque. The injection
molded interface element comprises a rated break section between
its mounting portion and its coupling portion. The injection molded
interface element comprises a mold material having shape stability
at common sterilization temperatures, wherein the injection molded
interface element comprises a deformation indicating pattern
indicating a pre-breaking deformation. Both, the shaft and the
interface element each have an elongated through bore, the both
through bores aligning to each other.
[0011] A method for manufacturing a reaming device, comprises
wrapping a carbon fiber layer over an outer surface of a mounting
portion of a shaft. A surface structure is pressed on an outer
surface of the carbon fiber layer. An interface element is
injection molded over the surface structure. The wrapping comprises
impregnating the carbon fiber layer with an impregnation agent
being compatible with a material of the shaft. The shaft mounting
portion is prepared before wrapping a carbon fiber layer for
establishing a reliable connection between the shaft and the carbon
fiber layer. The pressing includes heat setting of the carbon fiber
layer in a closed mold. According to an exemplary embodiment of the
invention, a reaming device has a shaft with a mounting portion.
The mounting portion has an outer surface, a carbon fiber layer and
an injected-molded interface element for mechanically coupling an
external device. The injected-molded interface element has a
mounting portion. The carbon fiber layer extends over the outer
surface of the shaft mounting portion and has its own surface. The
carbon fiber layer outer surface has a surface structure. The
injection-molded interface element mounting portion is
injection-molded over the carbon fiber layer outer surface
structure. Thus, the shaft can be provided with an outer surface
structure, so that an injection-molded interface element can be
easily integrally formed on the shaft, i.e. the carbon fiber layer
extending over the shaft. Thus, the shaft can be designed to
fulfill the particular requirements for a shaft, for example
flexibility and a particular strength against breakage and wherein
the integrally formed injection-molded interface element may be
designed to fulfill the particular requirements for coupling an
external device. Such requirements may include for example a
particular geometry and particular material properties which may be
met by the injection-molded interface element.
[0012] According to an exemplary embodiment of the invention, the
shaft is made of a carbon fiber reinforced material. Thus, a
particular strength for preventing a breakage of a shaft can be
provided, in particular as a carbon fiber reinforced material has a
particular flexibility and elasticity while maintaining the
capability of transmitting torque forces, and at the same time
owing to the carbon fiber reinforced structure does not tend to
break into multiple fragments.
[0013] According to an exemplary embodiment of the invention, the
carbon fiber layer comprises a wrapped carbon fiber with a resin
impregnation. Thus, it is possible to bring the carbon fiber layer
into a particular shape which is required for molding over the
interface element. In particular, the resin impregnation may be a
thermosetting resin, so that a particular cast can be heated to set
the resin impregnation of the carbon fiber layer.
[0014] According to an exemplary embodiment of the invention, the
carbon fiber layer surface structure comprises a pressed tooth
structure. Thus, a reliable connection between the shaft and the
carbon fiber layer, respectively, on the one hand and the molded
interface element on the other hand may be established. In
particular, a tooth structure allows for a mechanically reliable
force transmission between the shaft and the interface element.
[0015] According to an exemplary embodiment of the invention, the
interface element comprises a coupling portion for coupling a power
tool reamer drive as an external device. Thus, a drive or any other
power tool may be coupled to the coupling portion of the interface
element in order to drive the shaft.
[0016] According to an exemplary embodiment of the invention, the
coupling portion comprises an end portion being capable of
transmitting a torque. Thus, a torque of a power tool can be
transmitted to the shaft via the interface element. In particular,
the end portion may be designed as a hexagonal cross-section.
However, it should be noted that also any other angular geometry
may be used. It should be noted that also a free-shape
cross-section may be used, e.g. having a waved outer contour. In
particular, a unique cross-sectional shape may be used in order to
guarantee the correct use of a particular tool together with the
corresponding reaming device. In other words, the coupling of an
intended combination of a reaming device and a corresponding power
tool may be established by a unique corresponding coupling geometry
between the power tool and the respective coupling portion or end
portion of the interface element.
[0017] According to an exemplary embodiment of the invention, the
injection-molded interface element comprises a rated break
arrangement or geometry (having a predetermined sheer strength)
between its mounting portion and its coupling portion. Thus, a
predetermined breaking point or a weak section can be established
so that the reaming device will break at this particular section
when exceeding a predetermined torque. In particular, this may
avoid an unintended break at a location which is not accessible,
for example close to the reaming head. In other words, the
predetermined breaking point or rated break point will be
established in a safe and accessible region of the reaming device
so that no broken parts of the reaming device remain in the
patient's body.
[0018] According to an exemplary embodiment of the invention, the
injection-molded interface element comprises a mold material having
shape stability at common sterilization temperatures. Thus, it can
be guaranteed that the reaming device cannot be sterilized without
losing its particular geometry properties. This is of relevance if
providing the reaming device as a single use device. In case, if
the surgeon tries to use the reaming device again, he has to
sterilize the reaming device, but during this sterilization, the
reaming device will be predeterminently destroyed to avoid any
reuse of the reaming device. It should be noted that either the
entire interface element may be made of the non-heat resistant
material, or only particular sections thereof may be made of the
non-heat resistant material, if using for example a two stepped
molding process using two different molding materials. It should
also be noted that a heat resistant portion may be provided to
maintain an "emergency" geometry, which however is not comfortable
geometry for surgery. In particular one component of a multiple
step mold may be heat resistant and the other component of a
multiple step mold may be not heat resistant. The lost form
stability may also be established by the impact of another
parameter of sterilization, e.g. steam or the like. Thus, the
interface element may be designed to lose its form stability when
being treated by steam.
[0019] According to an exemplary embodiment of the invention, the
injection-molded interface element comprises a deformation
indicating pattern indicating a pre-breaking deformation. Thus, the
surgeon can directly recognize a critical deformation of the
interface element when recognizing the indicating pattern. This
indicating pattern may be for example a longitudinal line or a
longitudinal groove extending into the longitudinal direction of
the interface element. In case the longitudinal groove or line
deforms for example like a helix, the surgeon knows that a torque
is applied, or that a particular threshold may be extended. It
should be noted, that also an interfering grid may be used as a
deformation indicating pattern, so that for example a particular
Newton pattern may occur at particular stages of deformation, so
that a particular Newton pattern may be used as an indicative for
the grade of deformation.
[0020] According to an exemplary embodiment of the invention, both,
the shaft and the interface element each have an elongated through
bore, wherein the both through bores align to each other. Thus, a
guide wire or a securing wire can be inserted into the aligning
through bores. A guide wire may be used for an improved targeting
of the reaming device, wherein a securing wire may be used for a
reaming head being provided at the reaming device.
[0021] According to an exemplary embodiment of the invention, a
method is provided for manufacturing a reaming device, comprising:
wrapping a carbon fiber layer over an outer surface of a mounting
portion of a shaft. A surface structure is pressed onto an outer
surface of the carbon fiber layer. An interface layer is
injection-molded over the surface structure. Thus, in particular
when using a shaft made of a carbon fiber reinforced material, a
carbon fiber layer may provide a reliable and compatible connection
between the carbon fiber layer and the shaft. The outer surface
structure of the carbon fiber layer establishes a reliable
mechanical connection between the carbon fiber layer and the
injection-molded interface element. In particular, such a method
allows manufacturing a reaming device without having undue material
tensions during a manufacturing process, as an injection-molding
more or less provides a material morphology having a low or no
material tensions.
[0022] According to an exemplary embodiment of the invention,
wrapping comprises impregnating the carbon fiber layer with an
impregnation agent being compatible with a material of the shaft.
Thus, a reliable connection between the shaft and the carbon fiber
layer may be established.
[0023] According to an exemplary embodiment of the invention, the
method further comprises preparing a shaft mounting portion before
wrapping a carbon fiber layer for establishing a reliable
connection between the shaft and the carbon fiber layer. Thus, a
kind of priming can be carried out before mounting the wrapped
carbon fiber layer onto the shaft in order to establish a reliable
connection being capable of transmitting torque.
[0024] According to an exemplary embodiment of the invention,
pressing includes heat-setting of the carbon fiber layer in a
closed mold. Thus, a fast and reliable manufacturing process can be
established. In particular, when using a mold of a thermoplastic
material and a thermosetting impregnation for the carbon fiber
layer, a defined weak section can be established allowing a
reliable transmission of forces and at the same time a predefined
weak section as described above.
[0025] It should be noted that the above features may also be
combined. The combination of the above features may also lead to a
synergetic effect, even if not explicitly described herein in
detail.
[0026] These and other aspects of the present invention will become
apparent from and elucidated with reference to the embodiments
described hereinafter.
BRIEF DESCRIPTION OF THE DRAWINGS
[0027] FIG. 1 illustrates a shaft for a reamer with a carbon fiber
layer before wrapping;
[0028] FIG. 2 illustrates a shaft with a wrapped carbon fiber
wrapping having a surface structure;
[0029] FIG. 3 illustrates a cross-sectional view of a shaft with an
overmolded interface element;
[0030] FIG. 4 illustrates an outer view of a shaft with an
overmolded interface element; and
[0031] FIG. 5 illustrates a schematic flow chart of a method for
manufacturing a reaming device.
DETAILED DESCRIPTION
[0032] FIG. 1 illustrates a shaft 10, in particular a reamer shaft
having a mounting portion 11. The shaft 10 has an outer surface,
onto which a carbon fiber layer 30 is wrapped. FIG. 1 illustrates
the carbon fiber layer 30 in an unwrapped condition.
[0033] FIG. 2 illustrates the end portion of a shaft 10, wherein
the carbon fiber layer 30 is wrapped around the outer surface of
the mounting portion 11. As can be seen from FIG. 2, the carbon
fiber layer comprises a surface structure 34 on the outer surface
33 of the carbon fiber layer. This outer structure may be formed
for example as a tooth structure or a rippled or ripped structure,
wherein ripples or rips run along a longitudinal direction of the
shaft 10. It should be noted that the rips of the surface structure
34 may also run in a helical way in order to carry not only
circumferential forces, e.g. torque forces, but also forces in a
longitudinal direction of the shaft, like pushing or pulling
forces. It should be noted that the surface structure 34 may also
have any other structure being capable of transmitting forces from
the shaft 10 to an interface element 20 or vice versa such as for
example splines.
[0034] FIG. 3 illustrates a cross-sectional view of the end section
of a shaft 10 provided with an overmolded interface element 20. The
interface element 20 has a mounting portion 21, which engages with
the surface structure of the carbon fiber layer outer surface 33,
34. Thus, forces can be transmitted from the shaft 10 to the
interface element 20. The interface element and the shaft 10 both
may comprise a through bore 19, 29, respectively, which through
bores may align. Thus, a guide wire or a securing wire can be
inserted through the aligned through bores 19, 29 so as to serve as
a guide for the reaming tool and the reaming process, as well as
securing for example a reaming head to be mounted on the other end
section of the shaft (not shown). The injection-molded interface
element 20 may comprise a rated break section 26, which may be for
example a groove or a notch. As the interface element 20 also
comprises a coupling portion 25, the rated break point section 26
can be provided between the mounting portion 21 on the one hand and
the coupling portion 25 on the other hand. The coupling portion 25
may serve for coupling a power tool or a drive tool for driving the
reaming device. By providing the rated weak section 26 between the
coupling portion 25 and the mounting portion 21, an overburden of
torque may lead to a predefined breakdown of the rated break
section 26. As this section 26 may be designed as the weakest
section with respect to a torque of the entire reaming device, a
predefined breakdown or fracture of the rated section 26 avoids a
breakdown or fracture on a more critical section, like for example
close to the reamer head or the shaft being inserted into the
patient's body. Thus, in case the reamer breaks, the rated break
section provides a break location being outside of the body of the
patient. The coupling portion 25 may further comprise a particular
geometry for transmitting torque forces, for example the outer
shape of a hexagonal cross-section in order to transmit torque
forces. However, also a particular cross-sectional shape can be
selected, which may be a unique cross-sectional shape which only
fits to the corresponding power tool. Thus, it can be avoided that
a not-matching combination of a reaming device and a power tool
will be used.
[0035] The material of the injection-molded interface element may
be a material which loses its outer shape when being exposed to a
common sterilization or autoclave temperature (greater than about
120.degree. C.). This may be of relevance when providing a reaming
device for single use only. Thus, if trying to sterilize the
reaming device, the outer shape of the interface element loses its
predetermined shape, so that a further use of the reaming device is
not possible. Thus, a re-use of a reaming device being intended for
single use only can be avoided.
[0036] FIG. 4 illustrates the end portion of a reaming device
having a shaft 10 and an injection-molded interface element 20. The
injection-molded interface element 20 may be provided with a
deformation indicating pattern 28. This deformation indicating
pattern 28 may be for example a line extending into the
longitudinal direction of the reaming device. In case, the
interface element of the reaming device will deform, also the
deformation indicating pattern will significantly deform, so that a
surgeon will recognize the deformation. In particular, when
stopping to apply a torque on the interface element, the shape of
the deformation indicating pattern may be used as an indicative of
a deformation of the interface element, even if no torque force is
applied. If the interface element is deformed, it may be for
example not used any longer. Such a deformation indicating pattern
may be for example also an interference mesh or interference grid,
so that depending on the deformation, several particular
interference patterns may occur, which interference pattern may be
used as an indicative for the strength of the deformation. This is
illustrated as 28a and 28b. The pattern 28a is for example slightly
inclined with respect to the longitudinal axis of the reaming
device or the interface element 20, wherein the second pattern 28b
has a counter inclination. When, for example, providing these both
patterns 28a and 28b with an intermediate layer, so that the
deformation for example will increase the inclination of the first
pattern 28a, and decrease the inclination of the pattern 28b, an
occurring interference pattern may be used as a unique indication
for the extent of the deformation.
[0037] FIG. 5 illustrates a schematic flow of a method for
manufacturing a reaming device. In step S10, the surface of the
shaft may be prepared to provide an improved adhesion of the carbon
fiber layer 30. This process may be considered as a kind of priming
process. In step S20, the carbon fiber layer is wrapped over an
outer surface of a mounting portion of a shaft. This wrapping
optionally may comprise an impregnating process of the carbon fiber
layer with an impregnation agent such as for example PEEK so as to
increase the adhesion between the shaft 10 and the carbon fiber
wrapping 30. In a subsequent step S30, a surface structure will be
pressed on the outer surface of the carbon fiber layer. This can be
carried out for example by a heated cast and the use of a
thermosetting resin, so that step S30 may optionally include a heat
setting process in step S35. Finally, an interface element 20 is
injection-molded over the surface structure of the carbon fiber
layer.
EXAMPLE
[0038] The process for making a carbon fiber composite (CFC) reamer
shaft will now be described:
[0039] A prepreg fabric (Sigratex CE 8011-200-42-SGL Group) is cut
into specific pieces for the shaft and the connection area by using
a cutter; for example an Aristomat TL 1617. The pieces are then
wound on a metal core by using an automatic rolling table.
Cellophane tape is then wound over the CFC shaft to fit it and to
withstand the expansion during heating. This is done by using a
shrink film wrapper. The CFC shaft is then hardened in an oven and
the cellophane tape is removed. The CFC shaft is then ground to a
tolerance of .+-.0.05 mm and the core is removed. A small piece of
CFC prepreg is wound on the machine connection side to later get a
form fit for the injection molding part. A metal dovetail and the
drill side of the CFC shaft is threaded over a second core and a
CFC prepreg fabric is wound over both ends to fix the dovetail and
CFC shaft together. Any cavities present are filled with epoxy. The
CFC shaft with dovetail and machine side is then fixed in a mold
made of two semicircular parts. By closing the mold the form fit
for the later injection moulding of the machine connection and a
homogenous smooth transition between dovetail and CFC shaft will be
pressed on the shaft. The mold is heated in an oven again to harden
the epoxy. Then the machine connection is insert molded with a
torque limiter made of SAN on the CFC shaft.
[0040] It should be noted that the term "comprising" does not
exclude other elements and that the term "a" or "an" does not
exclude a plurality. Also elements described in association with
the different embodiments may be combined.
[0041] 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.
* * * * *