Patent Application
20100239380
The present invention relates to a reaming device, and in particular to a reaming device having a shaft with a carbon fibre reinforced structure.
Intramedullary nailing is the method of choice for the fixation of fractures in long bones, in particular in long extremities. To have a 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 bone curvature, and has also 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 for a sterilisation process. The adequate cleaning of the instrument in hospitals demands a high effort and takes a lot of time. Further, some hospitals are not prepared to clean such critical devices because of the high effort involved.
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 akronym 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 operation process in hospitals. Further, the nitinol material is a very expensive material.
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.
CH 668690 describes 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.
It may be seen as an object of the present invention to provide a more reliable reaming device.
The object of the present invention is solved by the subject matter of the independent Claims. Advantageous embodiments thereof are incorporated in the dependent Claims.
According to an exemplary embodiment of the invention, a reaming device comprises a rod element, an interface element and a connecting agent, wherein the rod element comprises a first connecting portion having a carbon fibre reinforced structure, wherein the interface element comprises a second connecting portion, wherein the first connecting portion and the second connecting portion are concentrically arranged to each other, and wherein the connecting agent is interposed between the first connecting portion and the second connecting portion.
Thus, a reaming device is provided, which does not have the cleaning problem of the spiral reamer of the prior art, and providing at the same time a more robust material due to the carbon fibre reinforced structure of the rod element. Further, the rod element having a carbon fibre reinforced structure portion is cheaper than the nitinol material of the prior art, and further much more robust. The connecting agent provides a reliable connection between the rod element and the interface element. The interface element may be a coupling element being capable of carrying a reaming tool of a reaming device, but may also be a coupling to a reaming drive of the reaming device. In other words, the interface element may be a coupling on both sides of the reaming device, on the drive input side and the drive output side of the reaming device. The connecting portions, i.e. the first connecting portion and the second connecting portion may be particularly prepared for receiving the connecting agent in order to provide a reliable connection between the rod element and the interface element.
According to an exemplary embodiment of the invention, the first connecting portion is provided on an outer surface of the rod element, and the second connecting portion is provided on an inner surface of the interface element.
Thus, the connection portion of the rod will be at least partially surrounded by the interface element, so that the interface element covers the connecting portion of the rod element. However, the first connecting portion may also be provided on an inner surface of the rod element, and the second connecting portion may be provided on an outer surface of the interface element. In this case, the rod element should be provided with a hole, into which the interface element may be inserted, in particular into which the second connecting portion of the interface element may be inserted. In both of the previously describe cases, the transit from the rod element to the interface element or vice versa may be designed as a smooth transit in order to avoid portions bearing the risk of trapping ablated tissue, which may be problematic with respect to the cleaning process of the reaming device.
According to an exemplary embodiment of the invention, the first connecting portion comprises a first recess, wherein the connecting agent engages into the first recess.
Providing the first connecting portion of the rod element with a recess provides an improved force transmission during the operation of the reaming device, since the force transmission is not limited to the share forces affecting between the connecting agent and the surface of the rod element on the first connecting portion. Moreover, the forces may also be transmitted by the interaction between a protrusion of the connecting agent engaging into the recess and the recess itself.
According to an exemplary embodiment of the invention, the first portion comprises a second recess, wherein the first recess and the second recess are displaced to each other in an axial direction of the rod element.
The provision of a second recess being displaced with respect to the first recess in an axial direction allows to form a further protrusion of the connecting agent so that a force distribution may be improved. The provision of a displacement into an axial direction further distributes the force impact locations to different axial positions, so that the weakening of the rod element in the area of the first connecting portion may be limited in order to avoid a break of the rod element.
According to an exemplary embodiment of the invention, the first portion comprises a third recess, wherein the first recess and the third recess are displaced to each other in a circumferential direction of the rod element.
The provision of several recesses being displaced in a circumferential direction may further improve the distribution of the transmitting forces in order to form an improved contact between the rod element and the interface element.
According to an exemplary embodiment of the invention, the interface element, in particular the second connection portion, comprises a fourth recess, wherein the connecting agent engages into the fourth recess.
The provision of a recess in the interface element provides also an improved force transmission between the connecting agent and the respective interface element.
According to an exemplary embodiment of the invention, the interface element, in particular the second connecting portion comprises a fifth recess, wherein the fourth recess and the fifth recess are displaced in an axial direction of the interface element.
The displacement of the fourth and fifth recess provides an improved force distribution in order to improved the force transmission between the connecting agent and the interface element. The provision of an axial displacement of the recesses may avoid a weakened structure of the interface element and to distribute the force transmission to a plurality of axially distributed locations.
According to an exemplary embodiment of the invention, the interface element comprises a sixth recess, wherein the fourth recess and the sixth recess are displaced in a circumferential direction of the interface element.
The provision of several recesses displaced in a circumferential direction may provide an improved geometry with respect to the force transmission between the connecting agent and the interface element.
It should be noted that a plurality of recesses may be provided which are displaced in both directions, an axial direction and a circumferential direction at the same time. Further, the number of recesses is not limited and may be provided according to the respective need of the application. Further, it should be noted that the connecting agent may engage into the several recesses, in particular also into the second, third, fifth and sixth recess, in order to improve the force transmission between the rod element and the interface element via the connecting agent. It should be further noted, that the recesses in the rod element and the recesses in the interfaces may at least partially correspond to each other with respect to the location of recesses, so that the recesses may face to each other. Thus, the respectively engaging portions of the connecting agent may form a kind of bolting connection between the rod element and the respective interface element. Further, it should be noted that, for example, the third recess may be provided even if there is no second recess, and that a fourth recess may be provided even if there is no first, second or third recess, and so forth. In other words, the recesses may be provided arbitrarily with respect to the need of the respective application.
According to an exemplary embodiment of the invention, at least one of the recesses is formed in a shape of a spherical hole.
The provision of a spherical hole provides the advantage over a cylindrical hole, in that the spherical hole does not provide any sharp chamfer or notch, which sharp chamfer or notch bears the risk of a breakage of the rod element. Thus, by means of a recess in form of a spherical hole a sharp notch or a sharp chamfer may be avoided.
According to an exemplary embodiment of the invention, at least one of the recesses is formed in a shape of a groove, which groove extends into a longitudinal direction of the rod element.
A groove extending in an axial direction has a larger cross-section than a hole, and therefore may provide an improved force transfer between the respective elements. It should be noted that the groove may have a cross-section of a half circuit in order to avoid sharp notches or sharp chamfers in order to avoid an unintended breakage of the respective elements.
According to an exemplary embodiment of the invention, at least one recess forms a through-hole in the interface element.
The provision of a through-hole is much easier to manufacture than a blind hole, in particular when providing such a hole into the inner wall portion of an axial directed bore hole.
According to an exemplary embodiment of the invention, the interface element is adapted to couple a reaming tool to the rod element.
It should be noted that the interface element may also be adapted to couple a drive to the rod element. With providing two interface elements, a first interface element for coupling a reaming tool and a second interface element as a coupling for a drive, the design, in particular the geometry of the connecting agent of both connections between the rod element and the interface element on the reaming tool side and the interface element on the drive side may be designed such that the connecting agent provides a predetermined breaking point on the drive side. Thus, if the driving forces extend over the capability of the intended limited force transmission of the connection between the rod element and the respective interface elements, the predetermined breaking point will be provided on the side of the driving interface element, so that during the operation procedure on or in a human body, the breakage takes place outside the human body, so that no residues of the reaming device remain in the human body. The predetermined breaking point may be provided by, for example, by a reduced number of recesses on the drive side with respect to the reaming tool side.
According to an exemplary embodiment of the invention, the rod element comprises a first conduit extending in a substantially longitudinal direction of the rod element.
The provision of a conduit within the rod element provides the possibility to provide a medical effective agent from the outside to the reaming tool side of the rod element and the respective coupled interface element. On the other hand, the conduit in the rod element provides the possibility to remove the ablated tissue from the reaming tool side to the outside.
According to an exemplary embodiment of the invention, the interface element comprises a second conduit, which conduit being connected to the first conduit of the rod element.
Thus, the second conduit in the interface element corresponds to the first conduit of the rod element, so that the material being transported through the conduit may be transferred from the interface element to the rod element and vice versa. A conduit may be provided for both kinds of interface elements, the interface element as a coupling for a reaming tool and the interface element as a coupling to the drive. It should be noted that the outlet of the conduit of the interface elements may also be provided on the outer wall side, i.e. on the lateral portion of the interface element, in particular when the provision of an agent is desired or the removal of tissue is desired.
According to an exemplary embodiment of the invention, the rod element is made from a carbon fibre composite (CFC).
According to an exemplary embodiment of the invention, the carbon fibres are wound in at least a first layer and a second layer, wherein the direction of the first layer and the second layer are inclined at an angle of substantially plus/minus 45°, respectively, with respect to a longitudinal axis of the rod element.
Thus, the carbon fibres are optimised to have a maximum torsional resistance together with a low bending resistance. It should be noted that also different inclination angles of the direction may be provided, if there is a need to adapt the torsional resistance and the bending resistance as well as the ratio of the torsional resistance and the bending resistance.
According to an exemplary embodiment of the invention, the connecting agent is an adhesive.
The adhesive provides a reliable connection between the rod element and the interface element. It should be noted that for a reaming device an adhesive should be used which is compatible with respect to the human body. An appropriate adhesive should be an adhesive which provides a reliable connection and a bio-compatibility at the same.
According to an exemplary embodiment of the invention, the connecting agent is a thermal hardening adhesive.
A thermal hardening adhesive provides the possibility of a longer manufacturing period, so that when obtaining the correct positioning of the rod element and the interface element to each other, the hardening process may be started, initiated by a heat impact.
According to an exemplary embodiment of the invention, the connecting agent is a multiple component epoxy resin.
Multiple component epoxy resins provide a reliable and strong connection due to the chemical process starting when mixing the multiple components of the epoxy resin or when impacting a heat. Thus, an ageing process or an early binding of the adhesive may be avoided.
According to an exemplary embodiment of the invention, the connecting agent is a third layer of carbon fibre, which third layer is wound around the first layer and the second layer, wherein the third layer is wound into a circumferential direction of the rod element. It should be noted that the first layer and the second layer of the carbon fibre do not have to be separated, and may also constitute an interwoven structure. However, if the carbon fibres are inclined with respect to a solely circumferential direction, the stability of the structure may be weakened, so that the winding of a third carbon fibre layer in a circumferential direction provides a sufficient stable structure, in particular when the third carbon layer serves as a connecting agent. The third carbon layer may serve as a connecting agent in cases, the rod element and the interface element are connected by a press fitting, which does not need an adhesive for a reliable connection between the rod element and the interface element.
It should be noted that the above features may also be combined. The combination of the above features may also lead to synergetic effects, even if not explicitly described in detail.
These and other aspects of the present invention will become apparent from and elucidated with reference to the embodiments described hereinafter.
Exemplary embodiments of the present invention will be described in the following with reference to the following drawings.
a and 3b illustrate the separated components of a reaming device according to an exemplary embodiment.
a and 4b illustrate the mounted components of
a, 5b, 5c and 5d illustrate a rod element having a connecting portion according to an exemplary embodiment.
a, 6b, 6c and 6d illustrate a rod element having a connection portion according to an exemplary embodiment.
a, 7b, 7c, 7d, 7e and 7f illustrate an interface element serving as a coupling for a reaming tool according to an exemplary embodiment.
a, 8b, 8c and 8d illustrate an interface element serving as a coupling to a drive according to an exemplary embodiment.
a, 9b, 9c and 9d illustrate an interface element serving as a coupling to a drive according to an exemplary embodiment.
As can be seen, recess 23 is displaced in the longitudinal direction 28 to the recess 25. The same is valid for the recesses 13 and 15, which are displaced to each other with respect to the longitudinal axis 18 of the rod element 10. The recesses of the interface element 20 are provided as bore holes. It should be noted that the recesses may also be displaced with respect to a circumferential direction of the interface element 39, as can be seen from the recesses 23 and 24, which are displaced by about 180°, however any other degree of displacement may be applied according to need. Although
If, for example, leaving out the fourth, fifth and sixth recess on the driving side interface element 30 of
a and
a and
a, 5b, 5c and 5d illustrate the rod element 10, and in particular the connecting portion 11 of the rod element 10. In the connecting portion 11 of the rod element 10, there may be provided recesses 13, 14 and 15, wherein the recesses may be displaced with respect to the longitudinal direction, as can be seen in
Further,
a, 6b, 6c and 6d illustrate a further exemplary embodiment, illustrating recesses 13, 14, 15 on the surface side of the rod element 10, which recesses are formed as grooves into a longitudinal direction of the rod element 10. The grooves may be displaced with respect to the longitudinal axis of the rod element 10, as can be seen from
a illustrates further a first layer 17a and a second layer 17b of the carbon fibres, wherein the carbon fibres in the embodiment of
a, 7b, 7c, 7d, 7e and 7f illustrate an interface element 20, which is adapted to couple a reaming tool. The coupling of the reaming tool takes place at the head of the interface element 20, a detail of which is illustrated in
c illustrates a top view of the illustration of
a, 8b, 8c and 8d illustrate a further exemplary embodiment of an interface element, however this interface element is adapted to couple a drive for driving the reaming device.
a, 9b, 9c and 9d illustrate a further exemplary embodiment of an interface element 30, which is adapted to be coupled to a drive.
The interface elements of
It should be noted that the term ‘comprising’ does not exclude other elements and the ‘a’ or ‘an’ does not exclude a plurality. Also elements described in association with the different embodiments may be combined.
It should be noted that the reference signs in the Claims shall not be construed as limiting the scope of the Claims.
| Filing Document | Filing Date | Country | Kind | 371c Date |
|---|---|---|---|---|
| PCT/EP2007/006771 | 7/31/2007 | WO | 00 | 6/3/2010 |
