DE202006010535U1 - Implant to be used for hip replacement, comprising complementary conical twin surfaces at opening and insertion part - Google Patents

Abstract

The implant (10) is assembled of a shaft element (12) to be inserted into a cavity prepared at the femur and a neck element (14) to be joined to the shaft (12). The shaft (12) is of a slightly curved shape and wider at the top. An opening (16) at the upper end has two conical surface segments (18,20) and two straight segments (22,24) located inside. The neck element (14) is made all of a piece with an extension (32) to be inserted into the opening (16) designed in a shape complementary to the inner surface of the space (16).

Description

The The present invention relates to an implant comprising at least a first implant part and one with the first implant part connectable by a cone connection second implant part, wherein the first implant part has a conically shaped recess and the second implant part corresponding to the recess or essentially correspondingly shaped and insertable into this and clamped or press-fitted in a connecting position having a conically shaped projection.

implants The type described above are for example in the form or as parts of hip joint endoprostheses known, in which the first implant part, for example by a Prosthesis stem and the second implant part by a neck element is formed. A firm connection between the two implant parts is by convention truncated So conical projection, attached to one of the two implant parts is arranged, and a projection corresponding to the recess secured on the other implant part.

Although in known implant systems with such conical connections it would still be excellent desirable, the strength of at least two implant parts comprehensive Implant or modular implant system further increase.

It is therefore an object of the present invention, an implant of initially described type to improve so that it has an increased strength. These Task is in an implant of the type described above according to the invention thereby solved, in that the recess has at least a first and a second conical wall section and that a radius of curvature of the first wall section greater than a radius of curvature of the second wall section.

The proposed according to the invention Further development has the advantage that the cone connection in the area the first wall section has a larger contact area, which in particular reduces abrasion under high loads can be. Furthermore can so optimally utilized cross-sectional geometries of implant parts become. In particular, you can so radii of curvature be maximized by wall sections, preferably where greater loads are expected, larger radii of curvature for the wall sections the cone connection selected become. About that In addition, the choice of different radii of curvature of the wall sections the advantage that a connection of the two implant parts together is unique. On additional Elements to uniquely connect the two implant parts together ensure, for example, in the form of additional projections and Recesses, according to the well-known key-lock principle a unique Ensure connection, can be dispensed with. The cone connection thus fulfills a dual function.

Advantageous it is when the first wall section merges directly into the second wall section. Thus, the projection on the second implant part can be particularly compact be formed.

Around a stability the connection of the two implant parts of the implant further increase, it is advantageous if the first wall section of the second wall section opposite or substantially opposite. Furthermore, so is a highly symmetrical design of the projection and the corresponding recess possible.

Around with elongated cross-sections to increase the stability of the compound one possible huge Promote projection and a correspondingly large recess to can, is it cheap if at least one between the first and second wall sections is flat or substantially flat wall surface portion is formed. So can one available standing space can be optimally used to a total of the largest possible contact area between make the recess and the projection.

Especially with implant parts which become narrower in cross section, it is advantageous when two substantially opposite wall surface portions are formed and when a distance of the two wall surface sections decreases towards the second wall section. So, for example a remaining, surrounding the recess wall of the first implant part be formed with a constant thickness, whereby at the same stability a connection of the at least two implant parts a surface contact and thus a stability across from increased known implant systems is.

According to a preferred embodiment of the invention can be provided that the at least one wall surface portion at least partially parallel or substantially parallel to an outer boundary surface of the first implant part extends. In this way, a cross-sectional area of the first implant part can be optimally utilized in order to form a recess with the largest possible cross section. In particular, the thickness of the remaining wall surrounding the recess can thus be kept constant, thereby ensuring stability of the cone connection tion of the two implant parts is increased by the enlarged contact area between the recess and the projection.

Preferably takes an outer cross-sectional area of the first implant part, starting from a proximal end in the direction towards a distal end. Such an implant part is suitable for example, excellent as a stem of a hip joint endoprosthesis to serve in a corresponding recess of a femur bone can be used. Such a recess can for example form an optionally treated medullary canal of the femur, which also decreases somewhat in cross-section from the hip joint.

A optimal adaptation of an implant to a recess in which it can be used and whose width decreases in one direction, can in particular be achieved in that a width of a cross section of the first implant part at least in the region of the recess transversely to a connecting line between the first and the second wall portion decreases.

Advantageous is it when curvatures the first and / or second wall portion curvatures of an outer boundary surface of the first implant part are at least partially similar or when the first or second wall portion is parallel or substantially parallel to the outer boundary surface. So it is possible independently from a cross section of the implant part a maximum large recess form a contact surface between the recess and the projection of the second implant part to maximize. Below the outer boundary of the first Implant part is in particular the complete outer surface of the first implant part, that is, the entire outward of the Recess facing away surface of the first implant part, or even only a surface portion this entire outer surface.

Preferably For example, the first wall portion has a radius of curvature in a range from 4 mm to 10 mm.

Cheap is when the first wall portion has a radius of curvature in a range from 5 mm to 8 mm. Such a curved wall section is suitable itself as a wall section for a variety of applications, for example, for hip joint endoprostheses.

advantageously, the second wall portion has a radius of curvature in the range of 3 mm to 7 mm, which is always smaller than a radius of curvature of the first wall section.

Advantageous it is when the second wall portion has a radius of curvature in a range from 3 mm to 5 mm. This allows it, even very slim and small implants with a stable cone connection equip.

Around one possible to achieve good fit between the projection and the recess is it is advantageous if starting from an internal cross-sectional area of the recess from a proximal end of the first implant part in the direction decreases towards a distal end of the first implant part. So In particular, the desired Conical connection can be achieved easily.

According to one preferred embodiment of Invention may be provided that the projection at least one first and a second outer conical Has cone wall portion and that a radius of curvature of the first cone wall portion greater than a radius of curvature of the second cone wall section. Preferably correspond the radii of curvature the adjoining cone wall sections or wall sections of the second or first implant part.

Especially in cases, in which the first wall section merges directly into the second wall section, is it cheap when the first cone wall section merges directly into the second cone wall section. So can a contact surface between the recess and the projection are maximized.

Around to be able to form a projection with a high symmetry, is it is advantageous if the first cone wall section and the second Konuswandabschnitt away from each other or substantially from each other point away.

at Implants whose first implant part between the first and the second wall portion at least one plane or substantially ebe nen wall surface section it is convenient, if at least between the first and second cone wall sections a planar or substantially flat cone wall surface portion is formed, because so can a contact surface between the projection and the recess are maximized.

For maximizing a contact surface between the projection and the recess, in particular in the case of implants which have mutually substantially opposite wall surface sections and in which a distance of the two wall surface sections in the direction of the second Wall portion decreases, it is advantageous if two substantially facing away from each other Konuswandflächenabschnitte are formed and when a distance of the two Konuswandflächenabschnitte decreases in the direction of the second cone wall portion.

Preferably For example, the first cone wall portion has a radius of curvature in a range from 4 mm to 10 mm. Cheap it is there when the radius of curvature of the cone wall portion the radius of curvature of the wall portion corresponds to which he in the connection position is applied.

ever according to the size of the implant it can be cheap when the first cone wall portion has a radius of curvature in an area from 5 mm to 8 mm.

advantageously, the second cone wall portion has a radius of curvature in a range from 3 mm to 7 mm. Optimally, the radius of curvature corresponds the second cone wall portion the radius of curvature of the wall portion, on which the second cone wall portion in the connecting position is applied.

at especially small implants, it can also be beneficial if the second Cone wall portion a radius of curvature in a range of 3 mm to 5 mm.

Around a clamping and / or self-locking connection between the projection and to reach the recess, it is advantageous if a cross section the projection toward a distal end of the second implant part decreases.

In principle, it would be conceivable the implant in different places in a human or animal body use. According to one preferred embodiment The invention may in particular be provided that the implant a hip joint endoprosthesis is and that the first implant part in the form of a shaft and that the second implant part in the form of a modular neck the hip joint endoprosthesis are formed. This embodiment makes it possible to modular hip joint endoprostheses to equip with an improved connection between the shaft and neck part.

Around to minimize a number of connections of parts of the implant, it is advantageous if the modular neck part a neck portion has, integrally formed on the conically shaped projection on the distal side is.

Around the shaft of the hip joint endoprosthesis with To connect a joint socket, it is advantageous if the modular neck portion further carries a head portion or with a head portion the hip joint endoprosthesis is connectable. The head part can in particular be spherical be a ball joint with a corresponding hollow sphere be able to train molded socket.

advantageously, is the hip joint endoprosthesis a short stem prosthesis. This makes it possible in particular, the Shank of the hip joint endoprosthesis Anchor without using bone cement in a femur bone.

Around preferably To remove little bone substance of the femur, it is advantageous if a shaft length of the shaft is maximum 15 cm.

The The following description of a preferred embodiment of the invention serves in conjunction with the drawings for further explanation. It shows the

Figure: a perspective view of a portion of a modular hip joint endoprosthesis.

Implants according to the invention can For example, in spine surgery be used. It would be possible Here a cone connection in particular between a voltage applied to a vertebral body Part of an intervertebral disc implant and one on this by means of Cone connection fixable joint part. It would also be conceivable modular knee prostheses consisting of two or more parts, weitergebil Deten by means of an invention Connecting cone connection. However, implants according to the invention can also in the form of hip joint endoprostheses or parts thereof, which will be described in more detail below embodiment explained in detail shall be.

The figure shows a total with the reference numeral 10 provided implant according to the invention, which forms one or a part of a hip joint endoprosthesis. The implant 10 is modular and comprises at least two implant parts, namely a first implant part in the form of a usable in a prepared medullary cavity of a femur shaft 12 and a second implant part forming, with the shaft 12 connectible neck piece 14 , In the implant 10 it is preferably a modular implant, that is, it can be connected differently shaped neck parts with different shaped shanks. If several neck parts and / or shanks are provided, then those elements which are provided for forming a conical connection between the two implant parts are preferably provided are each formed the same, that is, there is preferably only one form of a recess or only one form of a recess corresponding to the projection.

For connection with the neck part 14 the shaft has at its proximal end a conical, open in the proximal direction recess 16 on, which has a first conical wall section 18 and a second, the first wall section 18 essentially opposite conical wall section 20 having. It would be conceivable that the two wall sections 18 and 20 directly merge into each other, but are in the embodiment shown in the figure between the first wall portion 18 and the second wall portion 20 two mutually substantially opposite planar or substantially planar wall surface portions 22 and 24 formed substantially parallel to an outer boundary surface 26 of the shaft 12 run.

The shaft 12 is shaped so that an outer cross-sectional area thereof starting from its proximal end, in which the recess 16 is formed, toward a distal end 28 decreases. Further, a width of a cross section of the shaft increases 12 in the region of the recess 16 across a connecting line 30 between the first wall section 18 and the second wall portion 20 towards the latter. Consequently, a distance of the two wall surface sections is reduced 22 and 24 towards the second wall section 20 out.

Curvature radii of the two wall sections 18 and 20 are not identical. Curvature radii of the first wall section 18 may in particular be in a range of 4 mm to 10 mm. In the embodiment shown in the figure, the radius of curvature of the first wall portion is 5.5 mm. The radius of curvature of the second wall section 22 is less than the radius of curvature of the first wall portion 18 and may be in a range of 3 mm to 7 mm. In the embodiment shown in the figure, the radius of curvature of the second wall portion is 5 mm.

The recess 16 uses a cross-section of a shaft 12 optimal, because in the area of the widening cross-section of the shaft 12 can the first wall section 18 have a maximum large radius of curvature which is greater than the radius of curvature of the second wall portion 20 ,

The neck part 14 has a substantially to the recess 16 corresponding projection 32 in the form of a conical pin, which is also referred to as oval cone. The projection comprises a first cone wall section 34 and a second cone wall portion facing away therefrom 36 , The first and second cone wall sections 34 and 36 Although they can pass directly into each other, in the embodiment shown in the figure, however, are between the two cone wall sections 34 and 36 two flat or substantially flat cone wall surface sections 38 and 40 formed in a connecting position in which the projection 32 into the recess 16 is introduced at the wall surface portions 22 respectively 24 issue. Curvature radii of the cone wall sections 34 and 36 essentially correspond to those of the wall sections 18 and 20 the recess 16 , The radius of curvature of the first cone wall section 34 is greater than the radius of curvature of the second cone wall section 36 , which has the immediate result that the two substantially facing away Konuswandflächenabschnitte 38 and 40 towards the second cone wall section 36 converging, that is, a distance of the two cone wall surface sections 38 and 40 takes in the direction of the second cone wall section 36 down.

Preferably, the angles of inclination of the wall sections 18 and 20 slightly flatter with respect to one through the recess 16 defined longitudinal axis as the inclination angle of the cone wall sections 34 and 36 based on a through the projection 32 defined longitudinal axis. So can an optimal attachment of the projection 32 on inner surfaces of the recess 16 in the region of an upper edge of the recess 16 be achieved. Alternatively, it would also be conceivable angle of inclination of the wall sections 18 and 20 identical to angles of inclination of the cone wall sections 34 and 36 form, whereby a large-area contact between the on the wall section 18 adjacent cone wall section 34 and at the wall section 20 adjacent cone wall section 36 is reachable.

The neck part 14 is a total of one piece, that is the projection 32 is integral to a neck section 42 formed, which in turn has a frustoconical, rotationally symmetric cone 44 carries for connection to a condyle, not shown. If a whole set of neck parts is provided, then these differ essentially in their neck sections, that is, their position and / or angle relative to the projection 32 as well as their length, ie their extension between the cone 44 and the lead 32 ,

To connect the neck part 14 with a condyle, not shown, of the implant 10 is a conical, conical to the condyle 44 provided corresponding recess.

The particular embodiment of the cone connection with the recess 16 and the lead 32 allows due to the larger radius of curvature in the region of the first wall section 18 and the first cone wall section 34 In the highly loaded lateral area of the cone connection a larger contact area and thus less abrasion. A load on the conical connection of the implant 10 is usually in the form of a spatial alternating load, that is, the direction of the force action line is time-dependent. Consequently, the contact area within the cone connection is not consistent. Therefore, a round contact surface formed by wall sections 18 respectively 20 and to these corresponding cone wall sections 34 respectively 36 with the greatest possible curvature an optimal connection geometry with the highest possible congruence under changing load.

Claims (29)

Implant ( 10 ) comprising at least one first implant part ( 12 ) and one with the first implant part ( 12 ) by means of a cone connection ( 16 . 32 ) connectable second implant part ( 14 ), wherein the first implant part ( 12 ) a conically shaped recess ( 16 ) and the second implant part ( 14 ) one to the recess ( 16 ) corresponding or substantially correspondingly shaped and insertable in this and in a connecting position by clamping or held in a press fit conical shaped projection ( 32 ), characterized in that the recess ( 16 ) at least a first and a second conical wall section ( 18 . 20 ) and that a radius of curvature of the first wall portion ( 18 ) greater than a radius of curvature of the second wall portion ( 20 ). Implant according to claim 1, characterized in that the first wall section ( 18 ) directly into the second wall section ( 20 ) passes over. Implant according to one of the preceding claims, characterized in that the first wall section ( 18 ) the second wall section ( 20 ) is opposite or substantially opposite. Implant according to one of the preceding claims, characterized in that between the first and the second wall portion ( 18 . 20 ) at least one planar or substantially planar wall surface section ( 22 . 24 ) is trained. Implant according to claim 4, characterized in that two substantially mutually opposite wall surface portions ( 22 . 24 ) are formed and that a distance of the two wall surface sections ( 22 . 24 ) in the direction of the second wall section ( 20 ) decreases. Implant according to one of claims 4 or 5, characterized in that the at least one wall surface portion ( 22 . 24 ) at least in sections parallel or substantially parallel to an outer boundary surface ( 26 ) of the first implant part ( 12 ) runs. Implant according to one of the preceding claims, characterized in that an outer cross-sectional area of the first implant part ( 12 ) starting from a proximal end towards a distal end ( 28 ) decreases. Implant according to one of the preceding claims, characterized in that a width of a cross section of the first implant part ( 12 ) at least in the region of the recess ( 16 ) across a connecting line ( 30 ) between the first and second wall sections ( 18 . 20 ) decreases. Implant according to one of the preceding claims, characterized in that curvatures of the first and / or second wall portion ( 18 . 20 ) Curves of an outer boundary surface ( 26 ) of the first implant part ( 12 ) are at least partially similar or that the first or second wall section ( 18 . 20 ) parallel or substantially parallel to the outer boundary surface ( 26 ). Implant according to one of the preceding claims, characterized in that the first wall section ( 18 ) has a radius of curvature in a range of 4 mm to 10 mm. Implant according to claim 10, characterized in that the first wall section ( 18 ) has a radius of curvature in a range of 5 mm to 8 mm. Implant according to one of the preceding claims, characterized in that the second wall section ( 20 ) has a radius of curvature in a range of 3 mm to 7 mm. Implant according to claim 12, characterized in that the second wall section (FIG. 20 ) has a radius of curvature in a range of 3 mm to 5 mm. Implant according to one of the preceding claims, characterized in that an inner cross-sectional area of the recess ( 16 ) starting from a proximal end of the first implant part ( 12 ) towards a distal end ( 28 ) of the first implant part ( 12 ) decreases. Device according to one of the preceding claims, characterized in that the projection ( 32 ) at least a first and a second outer conical cone wall portion ( 34 . 36 ) and that a radius of curvature of the first cone wall portion ( 34 ) greater than a radius of curvature of the second cone wall portion ( 36 ). Implant according to claim 15, characterized in that the first cone wall section (FIG. 34 ) directly into the second cone wall section ( 36 ) passes over. Implant according to one of claims 15 or 16, characterized in that the first cone wall section ( 34 ) and the second cone wall section ( 36 ) away from each other or substantially away from one another. Implant according to one of claims 15 to 17, characterized in that between the first and the second cone wall portion ( 34 . 36 ) at least one flat or substantially flat cone wall surface portion ( 38 . 40 ) is trained. Implant according to claim 18, characterized in that two conical wall surface sections ( 38 . 40 ) are formed and that a distance of the two cone wall surface sections ( 38 . 40 ) in the direction of the second cone wall section (FIG. 40 ) decreases. Implant according to one of claims 15 to 19, characterized in that the first cone wall portion ( 34 ) has a radius of curvature in a range of 4 mm to 10 mm. Implant according to claim 20, characterized in that the first cone wall section ( 34 ) has a radius of curvature in a range of 5 mm to 8 mm. Implant according to one of claims 15 to 21, characterized in that the second cone wall portion ( 36 ) has a radius of curvature in a range of 3 mm to 7 mm. Implant according to claim 22, characterized in that the second cone wall portion ( 36 ) has a radius of curvature in a range of 3 mm to 5 mm. Implant according to one of the preceding claims, characterized in that a cross-section of the projection ( 32 ) in the direction of a distal end of the second implant part ( 14 ) decreases. Implant according to one of the preceding claims, characterized in that the implant ( 10 ) is a hip joint endoprosthesis and that the first implant part ( 12 ) in the form of a shaft ( 12 ) and that the second implant part ( 14 ) in the form of a modular neck ( 14 ) of the hip joint endoprosthesis are formed. Implant according to claim 25, characterized in that the modular neck part ( 14 ) a neck portion ( 42 ), to which the conically shaped projection ( 32 ) is integrally formed on the distal side. Implant according to one of claims 25 or 26, characterized in that the modular neck part ( 14 ) further carries a head portion or is connectable to a head portion of the Hüftgelenkendoprothese. Implant according to one of Claims 25 to 27, characterized that the hip joint endoprosthesis is a short stem prosthesis. Implant according to one of claims 25 to 28, characterized in that a shaft length of the shaft ( 14 ) is maximum 15 cm.