Prosthesis

Abstract

A prosthesis (1) with a receptacle (2) for an artificial prosthetic element (3) and with a stem (4) for intramedullary anchorage in a medullary canal (5) of a human or animal bone (6), wherein the stem (4) has a proximal stem region (7) with a through-opening (8) in which the receptacle (2) can be fixed at a predetermined acute angle (α) to the central longitudinal axis (11) of the stem (4), so that the stem (4) in the implanted position within the medullary canal (5) serves as a counter-bearing for the receptacle (2), which can be attached to the dividing surface (16) of the bone (6) with a support element (15, 26, 29), characterized in that the proximal stem region (7) engages in a recess (27) of the support element (26, 29) in a form-fitting manner and / or the recess (27) penetrates.

Description

The invention relates to a prosthesis, in particular a femoral prosthesis of a hip prosthesis, having a receptacle for an artificial prosthetic element of a joint pairing with a further artificial or existing natural further prosthetic element and having a shank, having a distal shank region, and a proximal shank region for in particular cement-free intramedullary anchoring in the medullary canal of a human or animal bone, in particular of the femur.The use of joint prostheses is widely used today and serves for the complete or partial replacement of a natural joint. After the femoral head resection for the surgical removal of the femoral head, the joint prosthesis is connected to the remaining bone by inserting an elongate shank of the joint component into a cavity of the long bone and anchoring there, if appropriate, by means of bone cement. Thus, for example, during hip joint surgery, the medullary canal of the femur is opened, optionally filled with bone cement and subsequently the shaft of the endoprosthesis is inserted.A femoral component of a hip joint prosthesis consists, for example, of a forged titanium alloy, having a distal shank region and a proximal shank region and a shank to be anchored in the femur of a human or animal, which shank has a metallic surface, for example also porous, in a preferably proximal shank region.In order to achieve a permanent fixation in the femur or in the femur, a very good primary stability is important, in particular in the case of hip joint prostheses implanted without cement. In order to support bone attachment and osseointegration or to promote bone growth of the femur and of the femur engagement, surface roughnesses can be provided in particular in a proximal shank region.In addition to the classic shaft prosthesis, DE 196 01 340 C1 discloses a femoral neck endoprosthesis for an artificial hip joint, which comprises a cement-less sleeve implantable in the upper region of a femur below the trochanter major with a receptacle for an artificial joint ball. An important articulation component of the endoprosthesis is a pressure plate with a through bore for passing through a tension screw, which is passed through a bore in the corticalis of the femur.The sleeve is prestressed by the tension screw as an abutment into its implantation position by means of the tension plate.DE 20 2005 020 876 U1 already discloses an endoprosthesis for a shoulder joint with a receptacle, designed as an intermediate piece, for a ball head and with a shaft for intramedullary anchoring in the humeral bone. The shaft has a proximal shaft region with a through-opening having an internal thread, in which a connecting member of an intermediate piece can be fixed at an acute angle with respect to the shaft axis, so that the shaft in the implanted position serves as an abutment for the receptacle, which abutment can be placed with one end of the intermediate piece on the separating surface of the bone.DE 10 2004 006 065 A1 discloses an implant which can be anchored with its proximal shaft part in a femur stump and is connected at its distal end to an exoprosthetic element. For this purpose, a sleeve is placed in a bone channel, through which a receptacle intended for an artificial joint ball passes. The sleeve is fixed by a screw which engages in the receptacle and penetrates the latter.Furthermore, DE 28 54 334 B2 discloses a femoral endoprosthesis having a neck part for an articular head, which neck part has a shoulder, and having a medullary cavity shaft for anchoring in a medullary canal of the bone. The medullary cavity shaft has a head part with an internal thread, in which the receptacle can be fixed with a neck angle relative to the longitudinal axis of the shaft, which thereby serves as an abutment.DE 195 01 995 A1 discloses an endoprosthesis for cement-free anchoring with a prosthesis shaft to be anchored in a bone in the longitudinal direction for receiving a joint ball, wherein the prosthesis shaft has a plurality of plates of plate-shaped design and its cross-sectional profile forms an open contour. As a result, the end prosthesis can be positioned in the spongy region without causing an interfering, medially or laterally directed compressive force in the bone interior.DE 196 107 41 C1 relates to a stem attachment prosthesis for an artificial hip joint, which is implantable without cement in the upper region of a femur and is referred to as a locking endoprosthesis and which requires only a slight resection of natural bone material compared to the stem prostheses. The distal end of the stem attachment prosthesis reaches only approximately into the region below the trochanter major into the medullary canal. For this purpose, a fastening system is provided which consists of the extramedullary plate forming an abutment and of a locking bolt. In the assembled state of the endoprosthesis, the locking bolt engages through the plate into the stem attachment prosthesis and clamps the plate to the corticalis of the femur in the implanted state. At the front end of the locking bolt, a receptacle is provided for receiving an artificial joint ball.DE 272 42 34 A1 discloses a joint prosthesis part with a ball head which is held by means of a plate on the femur shaft directly below the trochanter major. For this purpose, a tension rod is guided through this plate and engages into the receptacle for the ball head.Furthermore, it is known, for example, from EP 1 857 062 A1 to use an intramedullary locking nail for the care of fractures of the trochanter, the femoral neck or the femoral head, which nail can be driven proximally into the femur. Locking nails of this type have one or two obliquely running apertures for mounting a neck screw for screwing into the femur head. The locking nail has a locking pin which cooperates with the neck screw in such a way that it can move axially in only one direction and cannot rotate in the oblique through bore.US 2019 / 0 254 828 A1 relates to a hip joint prosthesis having a stem and a locking member configured to extend through the femoral component to fix the stem in the femur. The locking member may protrude from a distal opening on a medial side of the shaft adjacent the corticalis and may protrude beyond the distal opening with a tip portion. The locking element serves to increase the stability of the hip joint prosthesis against counterbore and rotation during ingrowth of the stem into the bone. For this purpose, the shaft is first inserted using standard surgical technology in order to achieve a proper press fit. The insertion of the locking element takes place as the last step of the shaft fixing as soon as the final position of the shaft is reached.Due to wear of the joint prosthesis, but also, for example, in the event of loosening of the endoprosthesis occurring over time, it may be necessary to remove it and replace it with a new one. The term revision endoprosthesis refers to all required surgical interventions in an already present endoprosthesis. The cause for this can be an increasing life expectancy, but also undesired events such as dislocation, fracture, loosening, material wear or infection. Revision endoprosthesis has become increasingly important in recent years. To avoid infections, after removal of the old prosthesis, the remaining bone cement must also be removed as completely as possible.DE 10 2004 043 315 A1 proposes removing the bone cement with the aid of a milling head guided on a guide rod.EP 0 910 317 B1 describes a surgical instrument for the mechanical removal of bone cement, in which the bone cement is removed piece by piece using a pneumatically driven chisel tool under endoscopic visual control.Furthermore, EP 3 570 788 B1 discloses a medical instrument for extracting an implanted prosthetic socket of a hip joint endoprosthesis from a femur bone if, during the implantation of the hip joint endoprosthesis, an excessively large or excessively small prosthetic socket has been inserted into the prepared bone cavity and the latter therefore has to be removed again.Further extraction devices are known from DE 92 12 846 U1 and EP 1 738 723 A1.The object of the present invention is to improve the anchoring of the shaft in the femur substantially and, in addition, to enable extraction of the implant, in particular due to defects or loosening at the implant, reliably and with low bone substance loss. In this case, the removal of bone substance present is to be reduced and, at the same time, weakening of the corticalis is to be avoided.The object is achieved according to the invention with an osseointegrated transcutaneous prosthesis, for example designed as a joint prosthesis or an endo-exo prosthesis, according to the features of claim 1. The further embodiment of the invention can be taken from the dependent claims.According to the invention, these only apparently conflicting goals of the invention, a reliable fixing with low loss of substance, a possibility for setting and adapting the position and orientation during the implantation and also, moreover, a simple possibility for extraction can be agreed for the first time by the shaft having, at least in its proximal shaft region, a through opening, in particular with an internal thread, as an abutment for receiving the prosthesis element, and the proximal shaft region engaging positively in a recess of the support element or passing through the recess. In the implanted position, the shaft is not necessarily clamped or cemented in the interior of the medullary canal, but forms the abutment for the receptacle, which is supported by a support element on the separating surface of the remaining bone. The support element and / or the shaft can consist of a metal or a plastic, wherein hybrid materials can also be used. For this purpose, the receptacle penetrates the shaft with its threaded section at an angle corresponding to the CCD angle (centrum-collum diaphysis), so that the threaded section enters the spongy structure on the side facing away from the prosthetic element, in particular below the trochanter major, but without penetrating the corticalis. According to the invention, an anchoring of the femoral prosthesis is thus achieved for the first time with extensive protection of bone substance present by a cylindrical shank and a threaded section without a wedge effect occurring in the medullary canal. Rather, the shaft serves as an abutment for the prosthetic element in that it lies flat against the corticalis intramedullaryly, in particular on one side, and thus transmits the required holding force over a large area. The loss of substance is extremely low, in particular the shaft can be made substantially smaller than in a commercially available intramedullary nail because, unlike in the intramedullary nail, the holding force does not arise due to the clamping effect due to the wedge effect or by means of bone cement within the intramedullary canal and the intramedullary canal accordingly does not have to be filled. In addition, a high holding force for the prosthetic element is already achieved when the shaft as such is movable within the medullary canal and is inserted into the medullary canal free of clamping forces in order to be able to reposition or orient the shaft as required. The force-locking fixing of the shaft is produced only as a result of the support element being mutually braced on the separating surface and the shaft on the inner side of the medullary canal facing the support element. By fixing the receptacle with its abutment, which is in particular designed as a threaded section, in the through-opening in the proximal shaft region, the receptacle is thus at the same time prestressed against the cut surface by a holding surface or collar-shaped contact surface of the support element, which can optionally also be exchangeable, wherein the tensile force can be generated by a rotation of the threaded section in the through-opening or, when the receptacle is fixed in a stationary manner in the abutment in a predetermined position, by means of a clamping means. The lateral protrusion of the receptacle on its end face facing away from the prosthesis element from the shaft circumference is dimensioned such that the threaded section protrudes with a length between 5 mm and 30 mm, but does not penetrate the corticalis, and accordingly an undesired loss of substance and a weakening of the bone structure are avoided. The protruding threaded section thus also serves at the same time for axially securing the shaft within the medullary canal and fixes the shaft within the medullary canal in its axial direction.By virtue of the proximal shaft region penetrating a recess of the support element or engaging in the recess in a positively locking manner, the stability of the receptacle is substantially improved by mutual penetrations of the shaft and of the support element. It can be provided that the shaft can be screwed with an external thread into an internal thread in the recess of the support element.According to the invention, a completely novel method of implantation, referred to as "3-point fixation", is provided, wherein the first fixation point is realized by the contact of the receptacle of the prosthesis element by means of the support element on the separating surface, the second fixation point by the contact of the distal shaft region within the medullary canal, and the third fixation point by the receptacle diagonally penetrating into the spongy bone structure opposite the prosthesis element. The 3-point fixation achieves a superior strength and load-bearing capacity with at the same time low implantation effort and low bone substance loss.An essential effect according to the invention is that the achievable fixing forces of the receptacle are transmitted by the shaft serving as an abutment, which for this purpose, as can be seen, does not require fixing by clamping force or bone cement. Rather, the shaft, which is introduced through a proximal opening into the medullary canal largely free of clamping forces, in a similar manner to bone nails, can be removed again without problems, so that optimal adaptation and adjustment can be carried out.The prosthesis according to the invention, which is securely anchored essentially by the shank and the receptacle with its threaded section as respectively cylindrical functional elements, opens up a possibility for revision which has hitherto been considered to be ruled out. This is because, although the cylindrical shaft grows gradually, regardless of its innovative manner of fixing in the medullary canal, it can nevertheless be removed again relatively easily. For this purpose, the receptacle is first released and removed from the through-opening of the proximal shaft region, optionally in conjunction with a rotational movement about its longitudinal axis, which is possible without problems according to experience. The remaining cylindrical shaft, in contrast, is often not releasable from the medullary canal even when a considerable tensile force is applied. In order to be able to remove the shaft nevertheless, a drill, in particular a crown drill or a drill bit, with an end-face cutting edge, which drill is designed at least in sections as a hollow body and encloses the shaft circumferentially, including a minimum annular gap, is used as the inspection tool, such that the shaft can be released without problems within the medullary canal by a corresponding advancing movement of the tool along the shaft. The end face of the shaft can finally be loosened from adhesions by a rotational movement of the shaft. The shaft can then be removed without any further action of force. A revision shaft with a diameter adapted to the drilling tool and enlarged compared to the shaft previously removed can subsequently be inserted and fixed without additional post-processing or treatment, wherein, if appropriate, even the previous recording can be used again. Additional operations are not required. It is easily understood that the loss of substance occurring is extremely small. Such a drilling tool cannot be used in the shaft prostheses known from the prior art not only because of the wedge shape, but above all also because of the upper shaft part which is connected integrally to the shaft and carries the head.A particular advantage of the prosthesis according to the invention is achieved in particular in that the medullary canal is only partially cleared, in particular drilled, for example to 1 / 3 of the shaft length, and the shaft is then driven in, whereby only a slight loss of substance occurs. In particular, in the further course of the medullary canal, the tissue present is merely displaced, i.e. not separated, during the introduction of the shaft and is placed against the rear side of the contact surface of the hollow-profile-shaped shaft. This results in direct contact of the tissue and the shaft, so that in particular no or no large distances have to be overcome. The hollow-profile-shaped shank therefore substantially promotes ingrowth.The shaft could have a constant or tapered shape in its proximal as well as distal shaft region, each with a circular cross-sectional shape. A particularly advantageous embodiment of the invention is achieved in that a circular cross-sectional area with a cylindrical circumferential contour as enveloping surface is determined by the proximal shaft region, and in that the distal shaft region is not laterally widened with respect to this cylindrical circumferential contour or the optionally also different cross-sectional areas of the distal shaft region lie within the cylindrical circumferential contour. The proximal shaft region thus defines the cylindrical circumferential contour, within which the distal shaft region can be designed virtually as desired or can be individually adapted. Thus, on the one hand, medical adjustments to the shaft area can be made for the first time, and on the other hand, the advantages of the possibilities for low-substance removal of the shaft can be optimally agreed within the scope of revision operations.Accordingly, a variant according to the invention has proven to be particularly advantageous in which the distal shaft region is designed at least in sections as a hollow body and / or has a concave cross-sectional shape in order to promote ingrowth of the shaft. Unlike the prior art, in which the design of the shaft often represents a compromise between the optimal fixation by ingrowth on the one hand and the releasability of the grown-in shaft from the medullary canal on the other hand, according to the invention the optimum of the geometry promoting ingrowth and the surface condition of the shaft and the mechanical stability is achieved, since the possible later removal of the shaft is possible without any problems independently of the progress of the ingrowth by means of the drilling tool.According to a particularly advantageous embodiment of the invention, such an optimized shaft design is achieved in that the distal shaft region between its distal end region and the proximal shaft region is designed at least in sections as an open hollow body or as a profile and / or has a perforated wall surface in order to ensure at the same time a high rigidity of the shaft region and to enable the accelerated ingrowth of tissue.Another configuration, which is also particularly practical, is achieved in that the distal end region has a continuously running convex shape, in particular spherical surface sections, and is rounded in order to avoid injuries to the tissue. When the shaft is introduced into the medullary canal, the substance present is thereby preferably laterally displaced and not severed. Suitable for this purpose are conical or conical end regions with a flattened end and also, for example, concave shapes rounded in spoon-like fashion.Furthermore, it has already proven particularly expedient if the receptacle has a support element for bearing on the separating surface with a contact surface which is concave in sections, in order to thus enable secure fixing which is independent of possible unevennesses of the separating surface. In addition, the orientation of the receptacle can be adapted by the concave contact surface before the support element is fixed in a force-fitting manner by increasing the prestressing force, in that the restricted rotational movability of the shaft about its longitudinal axis in the medullary canal is used for setting the desired position.It is also particularly advantageous if the surface condition promotes the ingrowth of the bone substance, in particular thus has a roughness or structuring.A further embodiment of the invention, which is also promising particular success, is achieved in that the distal shaft region extends as far as below the trochanter major, so that the shaft is optimally suitable for fixing the receptacle by means of its abutment through the massive distal shaft region, which consists of a solid material.The shaft is preferably shaped so that the bone substance present is damaged or impaired as little as possible by merely displacing it and not separating it. For this purpose, besides rounded end surfaces and circumferential surfaces, threaded or spiral-shaped basic shapes of the shank have also proven particularly expedient.In a particularly advantageous manner, the prosthesis according to the invention can also be used in osseointegrated prosthesis systems which are derived transcutaneously and in which a joint element is not provided. The prosthesis forms a so-called endomodule.A drilling tool for extracting the shank of the prosthesis is designed in the manner of a crown drill with a front-side cutting edge along an annular contour which encloses a cavity of the drilling tool at least in sections, wherein the inside width of the cavity is dimensioned slightly between 0.1 mm and 4 mm larger than the cylindrical circumferential contour of the enveloping surface of the shank. This makes it possible for the first time to remove the shaft from the medullary canal without a substantial loss of substance, in that the drilling tool is placed with its cylindrical cavity on the shaft, which is free of the receptacle, in the proximal shaft region and is moved translationally along the latter in the direction of the distal shaft region. The shaft serves as a guide, so that deviations from the central longitudinal axis of the shaft are fundamentally excluded. By means of a preferably adjustable depth stop of the drilling tool, the reaching of the end face of the distal shaft region is detected and the advancement of the drilling tool is ended. The end face which is unachieved by the drilling tool then only has a low adhesion, so that the shaft can be released from the grown tissue in the end region by introducing a torque. Of course, the drilling tool can be equipped with a suction and / or a coolant supply. Furthermore, sensors can also be arranged in the drilling tool for detecting essential parameters, for example the temperature.The invention allows various embodiments. To further clarify its basic principle, one of these is illustrated in the drawing and is described below. This shows in FIG. 1 is a front view of the prosthesis according to the invention, designed as a joint prosthesis, in a position fixed in the femur; FIG. 2 is a sectional view along line I-I of the prosthesis shown in FIG. 1, with a shaft integrated in the femur; FIG. 3 is an enlarged side view of the shaft; FIG. 4 is a perspective view of the shaft FIG. 5 shows a further perspective view of the shank; FIG. 6 shows a further sectional representation of the prosthesis with the shaft integrated in the femur; FIG. 7 shows a variant of the prosthesis shown in FIG. 3 in a sectional side view; FIG. 8 shows a further variant of the prosthesis according to the invention in a sectioned side view; FIG. 9 shows a further variant of the prosthesis according to the invention in a sectional side view.A femoral prosthesis 1 according to the invention of a hip joint prosthesis having a receptacle 2 for a spherical artificial prosthesis element 3, which is illustrated merely by way of illustration, is explained in more detail below with reference to the figures. The prosthesis 1 has a shaft 4 for cement-free intramedullary anchoring in the medullary canal 5 of a human or animal bone 6, which has a cylindrical cross-sectional shape in its proximal shaft region 7 and is made of a solid material of a suitable metal. In this proximal shaft region 7, a through opening 8 with an internal thread 9 is provided as an abutment for the receptacle 2. The longitudinal axis 10 of the through-opening 8, which is designed as a bore, is inclined with respect to the cross-sectional surface of the shaft 4 and encloses an acute angle α determined by the CCD angle with the central longitudinal axis 11 of the shaft 4. When performing the operation, the shaft 4 is first inserted into the medullary canal 5 opened as a result of resection with little force by a translatory movement. A pretreatment of the medullary canal 5, in particular the removal of tissue, is largely avoided in this case. To achieve this, different shaft lengths and / or shaft diameters can be used on a trial basis and the suitable shaft 4 selected. After the matching shaft 4 has been positioned in the medullary canal 5, the receptacle 2, which is cylindrical in its basic shape, is screwed into the internal thread 9 of the through-opening 8 with its threaded section 12 corresponding to the internal thread 9. In this case, the threaded section 12 penetrates the shank 4 as far as into the spongy bone structure 13 of the femur opposite the prosthetic element 3, without, on the other hand, penetrating the corticalis 14.The receptacle 2 already assumes at least approximately the desired position, whereby the axial position of the shaft 4 is already secured, but no resilient fixing of the shaft 4 is yet produced. This is created in the next step in that a support element 15 having a conical basic shape is aligned on the receiving element 2 on the separating surface 16 of the resection with a concave contact surface 17, which is simultaneously simulated to the original shape of the collum femoris. By means of a clamping means 18 embodied as a threaded clamping axis, the support element 15 on the receptacle 2 is subsequently prestressed against the separating surface 16, wherein the receptacle 2 is in turn supported on the shaft 4, on which the receptacle 2 is axially fixed by its threaded section 12, so that the shaft 4 serves as an abutment for the introduced fixing force. The shaft 4 in turn is supported along its main extension inside the medullary canal 5 on the medial side, as illustrated by directional arrows F.Unlike in the prior art, a high form-fitting holding force of the shaft 4 in the medullary canal 5 is therefore of no significance according to the invention for the fixation of the prosthesis 1. Rather, the shaft 4 merely serves as an abutment, so that the shaft 4 reaches its end position, if appropriate, also only after the introduction of the prestressing force by means of the clamping means 18 of the receptacle 2. The prosthesis element 3 can be attached to the receptacle 2 fixed in this way in a manner known per se, wherein a variant of the prosthesis element 3 which is integral with the receptacle 2 can also be realized. It is easily understood that the manipulations required on the remaining bone substance due to the fixation of the prosthesis 1 are much less than in the prior art. On the one hand, an outer abutment plate known from the prior art, which is to be mounted below the trochanter major 19, requires an additional opening of the corticalis 14 and moreover changes the outer contour of the femur according to the outer dimensions of the abutment plate, which has proven problematic in many cases. On the other hand, prostheses 1 known from the prior art with a wedge-shaped shank 4 lead to an undesired wedge effect and thus to spreading forces in the medullary canal 5 and, in addition, do not permit repositioning of the prosthesis 1 after driving into the medullary canal 5, so that positioning errors that occur cannot be corrected. The prosthesis 1 according to the invention thus already combines several essential advantages during the introduction of the prosthesis.However, there is also a further advantage in the case that the prosthesis 1 has to be removed from the bone 6, for example after prolonged use, which, as is known, leads to considerable problems on account of the wedge shape of the shaft prostheses known from the prior art and the additional tissue adhesions. At least in many cases, removal counter to the original joining direction is no longer possible, which consequently leads to a substantial engagement in the bone substance.The invention makes use of the fact that the shank 4 does not require a wedge shape and can therefore be cylindrical. The shaft consists of the solid proximal shaft region 7 with the through-opening 8, which has a circular cross-sectional area and thereby determines a cylindrical circumferential contour 20 as the enveloping surface. The adjoining distal shaft region 21 is preferably not solid, but-as can be seen in particular in FIGS. 3 to 5-is designed as a hollow profile with a closed contact surface 22 and a concave opening 23 facing away, in order to promote tissue ingrowth. A distal end face 24 of the distal shaft region 21 is provided with a rounded portion 25, as can be seen in particular in FIG. 5, in order to be able to displace the tissue present in the medullary canal 5 largely without damage. It is essential here that the contour of the distal shaft region 21 is not widened radially beyond the cylindrical circumferential contour 20, so that each cross-sectional area of the distal shaft region 21 lies within this circumferential contour 20.For the removal of the shank 4, a drilling tool, not shown, with a front-end cutting edge, which is designed in the manner of a crown drill and encloses a cylindrical cavity, is used. This cavity corresponds to the cylindrical circumferential contour 20 of the shank 4, i.e. is only slightly larger than the maximum shank diameter, and can therefore be placed on the shank 4 and moved along the latter as a guide during the drilling machining. The handling of the drilling tool is thus conceivable simple, because the shank 4 determines the orientation of the drilling tool as a guide. When a sufficient drilling depth is reached, the drilling tool is removed and the shank 4 is separated from its front-side adhesions by a slight rotation. The loss of substance occurring during the removal of the shank 4 is extremely low. In addition, the intervention can be carried out quickly. A shank 4 can be inserted directly into the resulting channel again, which shank only has to have an oversize corresponding to the drilling tool.FIG. 6 illustrates the fixing of the support element 15 on the separating surface 16 of the bone 6 by means of the clamping means 18 in that the receptacle 2 is in turn supported on the shaft 4. As can be seen, sufficient relative movability of the support element 15 relative to the shaft region 7 of the shaft 4 is required for a reliable and loadable fixing. Otherwise, it cannot be reliably ruled out that the support element 15 is prestressed only with respect to the shank 4, but not or not sufficiently with respect to the separating surface 16. For this purpose, a gap s is provided in the axial direction and a gap S is provided in the radial direction, which can be realized in practice, for example, by an elongated hole in the support element 15.FIG. 7 shows a variant of the prosthesis 1 with a modified support element 26 with a recess 27 which is penetrated by the proximal shaft region 7. In this variant, since the shaft 4 in its proximal shaft region 7 with the through-opening 8 serves as an abutment for the receptacle 2 and at the same time penetrates the recess 27 in the support element 26 and preferably closes off with it in a contour-flush manner, a further improved stability and load-bearing capacity of the prosthesis 1 is achieved. At the same time, the two crossing points serve for centering the receptacle 2, as a result of which the positioning and orientation in the bone 6 is optimized.FIG. 8 shows a variant of the prosthesis 1 shown in FIGS. 6 and 7, wherein the support element 15 is fixed to the separating surface 16 of the bone 6 in addition to the clamping means 18 by an axially parallel fixing means 28.FIG. 9 shows a variant of the prosthesis 1 with a modified support element 29, in which the fixing means 28 is arranged below the prosthesis element 3 shown in FIG. 2 and inclined with respect to the axis thereof. As a result, the positioning of the support element 29 on the separating surface 16 can be carried out independently of the fixing of the prosthesis element 3 on the support element 29 and the clamping means 18 can be replaced. For example, the support element 29 can be used in the case of a non-detachable connection of the prosthesis element 3 to the receptacle 2.LIST OF REFERENCE CHARACTERS1 Prosthesis 2 Receptacle 3 Prosthesis element 4 Stem 5 Medullary canal 6 Bone 7 Stem region 8 Through-opening 9 Internal thread 10 Longitudinal axis 11 Central longitudinal axis 12 Threaded section 13 Bone structure 14 Corticalis 15 Support element 16 Separating surface 17 Contact surface 18 Clamping means 19 Trochanter major 20 Circumferential contour 21 Stem region 22 Contact surface 23 Opening 24 End surface 25 Rounded portion 26 Support element 27 Recess 28 Fixing means 29 Support element α Angle F Directional arrow s Gap S Gap

Claims

A prosthesis (1) having a receptacle (2) for an artificial prosthesis element (3) and having a shank (4) for intramedullary anchoring in a medullary canal (5) of a human or animal bone (6), wherein the shank (4) has a proximal shank region (7) having a through-opening (8), in which the receptacle (2) can be fixed at a predetermined acute angle (α) with respect to the central longitudinal axis (11) of the shank (4), such that the shank (4) in the implanted position within the medullary canal (5) serves as an abutment for the receptacle (2), which abutment can be placed by a support element (15, 26, 29) on the separating surface (16) of the bone (6), characterized in that the proximal shank region (7) engages in a positive-locking manner in a recess (27) of the support element (26, 29) and / or penetrates the recess (27).Prosthesis (1) according to claim 1, characterised in that a cylindrical circumferential contour (20) is defined as an enveloping surface by the proximal shaft region (7) with its circular cross-sectional surface, and in that the cross-sectional surface of the distal shaft region (21) lies within the cylindrical circumferential contour (20) of the proximal shaft region (7).Prosthesis (1) according to claim 1 or 2, characterised in that the distal shaft region (21) is designed at least in sections as a hollow body and / or has a concave cross-sectional shape and / or concave opening (23).Prosthesis (1) according to one of the preceding claims, characterized in that the distal shank region (21) is designed at least in sections in the region of its end face (24) as an open hollow body and / or has a perforated wall surface.Prosthesis (1) according to any one of the preceding claims, characterized in that the distal end face (24) has a continuously running convex shape.Prosthesis (1) according to one of the preceding claims, characterized in that the support element (15, 26, 29) of the receptacle (2) has an at least sectionally concave contact surface (17) for support on the separating surface (16).Prosthesis (1) according to one of the preceding claims, characterized in that the proximal shaft region (7) and / or the distal shaft region (21) is equipped at least in sections with a surface finish promoting tissue ingrowth or growth.Prosthesis (1) according to one of the preceding claims, characterized in that the support element (15, 26, 29) can be prestressed with respect to the shaft (4) by means of a clamping means (18) and / or a fixing means (28).Endo-exo prosthesis comprising a prosthesis (1) according to claim 1.

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