EP4031071A1

EP4031071A1 - Modular prosthesis for at least partial replacement of a tubular bone adjoining a joint

Info

Publication number: EP4031071A1
Application number: EP20771861.0A
Authority: EP
Inventors: Helmut D. Link; Sebastian SPATH
Original assignee: Waldemar Link GmbH and Co KG
Current assignee: Waldemar Link GmbH and Co KG
Priority date: 2019-09-18
Filing date: 2020-09-16
Publication date: 2022-07-27
Also published as: WO2021053004A1; JP2022548706A; KR20220064390A; AU2020351036A1; US20220401219A1; CN114423385A

Abstract

Modular endoprosthesis for at least partial replacement of a tubular bone (9), comprising, as module components, a shaft (1) for insertion into a bone cavity of the tubular bone (9), and an end piece (3) comprising a support body (31) with a neck part (32) arranged on the medial aspect thereof, wherein the module components can be coupled to each other and released from each other along a longitudinal axis of the shaft. The end piece (3) has at least two different surface configurations on its support body, namely a closed surface (6') on a medial aspect (36), and a porous configuration (6) of the surface on the opposite, lateral aspect (38). The latter permits and positions the adhesion of muscle tissue, specifically without suturing. The muscle trauma caused by suturing, and the peak loads that occur at the respective suture points, can thus be avoided by virtue of the invention, by means of the location-specific direct adhesion of the muscle. It is thus possible to achieve quicker and reliable mobilization of the patient, and this with a reduced risk of complications.

Description

Modular prosthesis for at least partial replacement of a long bone adjacent to a joint

The invention relates to a modular endoprosthesis for at least partial replacement of a tubular bone comprising, as module components, a shaft for insertion into a bone cavity of the tubular bone, an end piece comprising a support body and a neck part arranged on the medial side with a receptacle for a joint device. Various types of endoprostheses are known for replacing diseased or defective bones and joints. In particular, these are pure joint endoprostheses or those that also partially or completely replace the adjacent tubular bones. They have a shaft extending over the length of the long bone to be replaced. The shaft replaces or strengthens the diseased or missing area of the bone. It is often connected to a joint unit that replaces an adjacent joint (e.g. knee or hip). The dimensions of the prosthesis shaft must therefore be selected in accordance with the respective anatomy and pathology of the patient.

Modular endoprosthesis systems are known for adapting to individual needs. They comprise a shaft, possibly several intermediate pieces and an end piece, which mostly forms a joint component at the same time. Such a system is known, for example, from DE 20 2004 019 264 U1. A modular system from DePuy, Inc. (USA) with the designation Orthopedic Salvage System is also known from prior use which the end piece is provided with a circumferential porous coating.

It has been shown that a satisfactory growth behavior can be achieved with this on remaining bone remnants. However, there is room for improvement with regard to the connection to soft tissues, such as muscles in particular. Tests with a coating containing tantalum have shown that only an increase in connective tissue can be stimulated, but not the actually desired muscle connection.

The invention is based on the object of creating a modular endoprosthesis of the type mentioned at the outset, which has a better behavior with regard to muscle growth.

The solution according to the invention lies in the features of the independent claim. Advantageous further developments are the subject of the dependent claims.

In the case of a modular endoprosthesis for at least partial replacement of a tubular bone, comprising as modular components a shaft for insertion into a bone cavity of the tubular bone, an end piece comprising a support body with an anterior, posterior, lateral and medial side and with a neck part arranged on the medial side with a receptacle for a joint device, and at least one intermediate piece, the module components, for example, via plug connections or other types of connection, can be coupled and detached with one another along a longitudinal axis of the shaft, it is provided according to the invention that the end piece has at least two different surface designs on its Has support body, a closed surface on a medial side facing the neck part and a porous design of the surface on the lateral side facing away from the neck part. The terms lateral, medial, anterior and posterior are technical terms used in anatomy for directions. Here "lateral" means laterally, pointing outwards, "medial" laterally, pointing towards the (body) center, pointing anteriorly forwards and posteriorly pointing backwards.

The invention is based on the idea of making a favorable porous design of the surface for the growth of muscle tissue ge aims at a certain point, specifically only there and not circumferentially. This particular location is the lateral side; H. the side facing outwards in the implanted state. On the one hand, the porous design creates a basis for the reliable growth of soft tissues, including muscle tissue, and, on the other hand, the precise positioning of the porous design and its concentration on the specific location (and only there, i.e. not all around) specifically and specifically achieves a favorable growth behavior of the muscle, which is intended to attack precisely at this particular point in the sense of a favorable power transmission to the prosthesis (and thus to the corresponding extremity). In the case of an endoprosthesis for the proximal femur, the muscle which according to the invention is specifically offered a location-specific growth point is the so-called "gluteus medus".

The invention has recognized that with such a design a location-specific growth of the muscle can be achieved in such a way that a direct connection of the muscle results. The sewing conventionally required to connect the muscle to the end piece of the endoprosthesis is no longer necessary. The direct connection is capable of greater force transmission and is more robust, in particular to the technique of suturing the muscle that has so far been frequently used in the prior art. Because this sewing basically damages the Muscle and leads to a stress concentration in the area of the seams, which can lead to unfavorable stress peaks and thus to a negatively forecast fastening (safety). The design for direct connection avoids these disadvantages. The trauma to the muscle created by sewing and the stress peaks occurring at the respective seams can thus be avoided thanks to the invention with the location-specific direct growth of the muscle. A faster and more reliable mobilization of the patient can be achieved in this way and with a reduced risk of complications.

It is expediently provided that the porous design of the surface is designed as an open-line porous lattice structure which is formed from a plurality of typically regularly arranged unit cells; however, an irregular arrangement of the unit cells should not be excluded. Such an open-line structure promotes rapid growth of the muscle tissue into deeper lying pores, which results in a higher loading capacity of the muscle / endoprosthesis connection, thus also improving the power transmission between the muscle and the endoprosthesis. Advantageously, the ele mentary cells are designed as a built structure and each composed of an interior space and a plurality of interconnected webs surrounding the interior space. For example, such a built structure can be produced efficiently using additive processes (including 3D printing). In this way, components with complex cavity structures with undercuts can be manufactured quickly and in a controlled manner. The structure of the unit cells can be precisely defined here. This enables a defined arrangement of the cells and the elements forming them, in particular their webs. In particular, these methods are suitable for producing the implant from biocompatible material, in particular Their metallic material selected from a group comprising pure titanium, titanium alloys, cobalt chrome, tantalum, stainless steel and zirconium.

The porous lattice structure is advantageously provided with a growth-promoting coating. Such a coating accelerates the ongrowth and ingrowth of soft tissue, in particular special muscle material and their tendons. In addition to coatings made of calcium phosphate, coatings with tantalum material are particularly preferred.

The porous design expediently has pores with a width in the range between 0.4 and 2 mm, preferably 0.7 to 1.5 mm. These relatively large pores offer more favorable ingrowth behavior and, above all, anchoring potential for muscle tissue.

It is useful to design the support body and the porous design or the open-line porous lattice structure in a unitary manner.This avoids the need to assemble separate components, which results in advantages in terms of robustness, simpler and more direct manufacture and durability surrender. In particular, no failure of the joint connection or negative effects of the joint connection on the surrounding tissue are to be feared. This applies in particular with regard to the fact that, in the case of a unitary design, the entire support body including the porous design consists of completely identical material.

It is particularly preferred if the porous design extends from the lateral side like a half-shell to the frontal as well as to the posterior side. The porous design thus extends over a considerable area of the circumference of the supporting body carrying the neck piece, but without being completely circumferential. This becomes a broader one, however Precisely defined growth area for adjacent soft tissues, especially muscles, created. Here, half-shell is to be understood as qualitative; it does not necessarily have to be a circumferential angle of 180 °, in many cases it can also be less (or a little more). A range for the circumferential angle of the coating of approximately 120 ° to 210 ° is preferred. For qualification as half-shell-like, it is important that the porous design, starting from the lateral side surface, extends both to the front and to the rear (towards the posterior), but without also extending over the medial area (that would then be circumferential what should be excluded).

In particular in the case of the half-shell-like extension, but also in other cases, a rounding with a lateral flattening is expediently provided at the transition between the lateral side to the frontal side and / or to the posterior side. With such a flattening on the latera len side, a wider and relatively flat contact and growth surface for the surrounding soft tissue, in particular muscles, can be created. This favors growth over a larger area, which enables better and more robust power transmission from the muscle to the prosthesis. It is particularly preferred if the lateral flattening is flat or has a minimum radius of curvature of twice the distance from the anterior to the posterior side of the support body. The subsequent rounding ensures a harmonious, stepless and edge-free transition to the anterior or posterior, which avoids the risk of the soft tissue that has grown, in particular muscle, becoming detached in this critical area. It is particularly useful if the rounding has a radius of curvature that is at most a quarter of the distance from the frontal to the posterior side of the support body. In terms of a more comprehensive integration into the surrounding soft part tissue, it is also advantageous if the porous Gestal device also extends on an upper side of the support body, but continues to be rich only in a lateral area. With the extension to the top, a physio logically and anatomically favorable growth possibility for the muscle, in particular the gluteus medius, is created. This achieves a focusing of the growth area for the surrounding soft tissue, in particular muscle, on precisely this higher area. As already mentioned, this is physiologically and anatomically favorable, and this advantage can thus be used for more efficient integration of the prosthesis according to the invention into the surrounding soft tissue, in particular muscle. Alternatively or additionally, it is also expedient if a lower region of the end piece, in particular of its support body, remains free of the porous design. A growth of soft tissue in this area can thus be prevented or reduced, which in particular inhibits the growth of undesired connective tissue.

However, it should not be ruled out that a plurality of through holes arranged parallel to one another and extending from the frontal to the posterior side of the support body are additionally provided in the lateral area. This means that traditional fastening techniques can be used to further strengthen the fastening security. It is useful here if the through holes open out in the area with the porous design, and their respective mouths are provided with a closed border, which in turn is preferably completely surrounded by the porous design. On the one hand, this results in a uniform location for the introduction of loads, namely in the area of the porous design, specifically also in relation to the through holes. So everything stays concentrated in one place with comparable power ratios. The supporting body is advantageously tapered at its lower end and the porous design extends as far as the tapered area. In other words, this means that the porous design ends in the area of the transition to the taper. The attachment site is limited to the upper area of the support body, which provides an advantage with regard to the biomechanics and their leverage.

In a particularly expedient embodiment, the endoprosthesis according to the invention is designed so that it belongs to a prosthesis system that includes modular components, in particular also special interchangeable pieces and / or end pieces. Here, the modular components can be connected by means of matching connections, in particular plug connections and anti-rotation locks. This enables the endoprosthesis according to the invention to be integrated into existing Pro thesesystems, whereby the advantages of the known prosthesis system are linked with the advantageous effects of the invention.

The invention is explained in more detail below with reference to the attached drawings using an exemplary embodiment. Show it:

1 shows a view of a modular femoral prosthesis for a femoral component of a proximal hip joint with an end piece according to an exemplary embodiment;

Fig. 2 is a view of a total femoral prosthesis;

3a, b show a frontal and a perspective view of the end piece according to the exemplary embodiment;

4 shows a schematic representation of adjacent unit cells of a porous design; and Fig. 5 is a perspective view of a replacement inter mediate piece.

A modular endoprosthesis according to the exemplary embodiment shown in the figures is designed as a modular femoral component of a hip joint endoprosthesis for implantation on a femur 9. As essential components, it comprises a shaft part 1, an intermediate piece 2 and an end piece 3. The individual components 1, 2 , 3 are connected to one another in a rotationally fixed manner, for example via plug connections 5.

The shaft part 1 comprises a tapering anchoring area 11 in the lower section with several anchoring ribs 13 running in the longitudinal direction of the shaft part 1. The anchoring area 11 is designed to be implanted in a bone cavity (intramedullary canal) 91 of the femur 9.

The upper part of the shaft part 1 also includes a coupling part 12 with a larger cross-section. This has a cylindrical jacket and is connected via a conical plug connection (not visible in FIG. 1) by means of a male part and an adjacent intermediate piece 2 ordered female part connected to the intermediate piece 2. The intermediate piece 2 in turn is correspondingly connected to the end piece 3 via a wider re cone plug connection 5.

The end piece 3 is subdivided into two areas: on the one hand, it comprises, as the main component, a support body 31 with a female cone as part of the plug connection 5 to the intermediate piece 2 and a neck part 32 which comprises a retaining pin 33 formed as a cone stump for receiving a joint ball 34 as part of a joint device of an artificial hip joint, the joint ball 34 in the implanted state in a socket of an acetabular component (not shown) represents) of the artificial hip joint is pivotably mounted. The retaining pin 33 of the neck part 32 is arranged on a medial side 36 of the end piece 3; Opposite it is the lateral side 38 of the end piece 3, which are each connected via an anterior side 35 and a rear (posterio re) side 37. The distance between the anterior side 35 and the posterior side 37 determines the thickness d of the support body 31 On the other hand, the end piece 3 has, as a further main component, a porous design 6 of its surface, which is provided in an upper region of the support body 31 on the lateral side, and only there. This will be explained in more detail later.

Further components of the modular endoprosthesis are shown in FIG. One recognizes the end piece 3 *, which corresponds to the end piece 3, but in contrast to this does not have a laterally-sided porous design 6, but has a differently designed, namely closed and smooth upper surface 6 'all around. In this end piece 3 *, the intermediate piece 2 is again inserted. In contrast to the embodiment shown in Figure 1, however, the shaft part 1 * is not intended for anchoring in the intramedullary canal 91 of the femur 9, but instead completely replaces the natural femur 9 namely by a long shaft part, which is composed of several intermediate pieces 2 'and 2 "of different lengths. At the opposite lower end of the shaft part 1 *, a condyle piece 10 is arranged as a lower end piece. This forms the shape and function of the condyles of the natural It goes without saying that the modular components, as shown in both FIGS. 1 and 2, can be combined with one another or exchanged as desired it enables the modular endoprosthesis to be adapted to the respective anatomical conditions and bone or joint de to adapt the patient's effects. For a more detailed explanation of the end piece 3 and its porous surface design 6, reference is now made in particular to FIGS. 3a and b. It can be seen on the lateral side 38 in the upper area that the surface of the support body 31 is provided there with the porous surface design 6. Here, the porous surface design 6 extends from the La teralseite 38 also to the anterior and posterior. Thus, he extends the porous surface design 6 half-shell type also over the transition to the anterior side 35 and the posterior side 37. With respect to a central axis 30 of the end piece 3, the porous design 6 extends over a circumferential angle of about 160 °; The exact value is not so important as the fact that the porous design 6 does not run all around, that is to say that the angle is significantly smaller than 360 °, preferably at most 200 ° or even at most 180 °. In the remaining angular range, the surface 6 'is designed differently, namely closed and smooth in the illustrated embodiment.

The porous design 6 is located approximately in the upper Hälf te of the support body 31 of the end piece 3. The porous design 6 forms a defined starting point for soft tissue, specifically for the growth of the gluteus medius (not shown). Thanks to the porous design 6, the muscle can grow precisely on the area marked by the porous design 6 and not in other areas. In this way, a precisely defined connection of the muscle to the modular endoprosthesis is achieved. This effectively prevents growth in an undesired location.

An exemplary structure of the porous design 6 is shown schematically in Fi gur 4. In this exemplary embodiment, the porous design 6 is designed as an open-line porous lattice structure. This is formed by an additive process (3D printing), e.g. EBM Structure comprising a plurality of regularly arranged unit cells 4. In the exemplary embodiment shown, these are formed in that the unit cells 4 each have an interior space 40 and a plurality of interconnected webs 41, 42, 43, 44. This creates an open-line structure which, on the one hand, ensures good penetration thanks to numerous interconnected cavities 40 and, on the other hand, ensures a solid and robust attachment thanks to many existing undercuts, which is of considerable advantage, especially when connecting force-transmitting muscle tissue is. Furthermore, the porous lattice structure 6 can be provided with a growth-promoting coating 45. Expediently, this is also arranged in the individual unit cells 4, namely on the various webs 41, 42, 43, 44, and indeed also in the depth of the open-line porous design 6. This further promotes the ingrowth behavior and thus enables rapid and reliable Remobilization of the patient.

As can also be seen in FIGS. 3a) and b), the porous design 6 also preferably extends partially in addition to the upper side of the support body 31, but still exclusively in the lateral area of the upper side. A lower region of the support body 31, preferably the lower third, in which the support body 31 tapers in terms of its width, on the other hand, preferably remains completely free of the porous design 6 all around.

To further improve the ingrowth behavior, a flattening 39 is preferably provided on the lateral side 38 (see the area highlighted by the bold dashed lines in FIG. 3b)). This creates a more even structure there, which offers particularly favorable conditions for the muscle tissue to grow over a broad area. Here, "flat" is understood to mean no or only a slight curvature, whose radius of curvature R is at least the, preferably double, distance d from the anterior to the posterior side of the support body 31. In contrast to this, in the area of the transition from the lateral flattening 39 to the frontal or to the posterior side is made more rounded, and has a radius of curvature r that is at most half the distance d or less, in particular less than a quarter of the distance d.

Furthermore, one or more extending through holes 8 can be arranged transversely to the central axis 30 in the lateral region of the support body 31, which open device 6 in the region of the porous Gestal. Here, their respective mouths 80 are surrounded by a border 81 which surrounds the respective mouth 80 like a hofar. In this area, the surface is designed to be closed, so it is not porous.

Another useful supplement for the modular endoprosthesis is shown in FIG. It shows an interchangeable adapter 2 *. It is essentially designed like the intermediate piece 2 shown in FIGS. 1 and 2 and, like this, has a conical plug connection 5. In contrast to the intermediate piece 2, however, the interchangeable intermediate piece 2 * is also provided with a porous design 6 on its surface. This is constructed in accordance with the porous design 6, but covers the outer surface of the interchangeable piece 2 * completely circumferentially. This provides an exchange piece for the modular endoprosthesis that can be used wherever the medical indication calls for favorable conditions for the growth of soft tissue. The area of application of the modular endoprosthesis expands as a result.

Claims

1. Modular endoprosthesis for at least partial replacement of a long bone (9) comprising as modular components a shaft (1) for insertion into a bone cavity of the long bone (9), an end piece (3) comprising a support body (31) with an anterior, posterior, me dial and lateral side (35, 37, 36, 38) and with a neck part (32) arranged on the medial side with a receptacle for a joint device (34), and preferably at least one intermediate piece (2), the module components being coupled to one another. and are detachable along a longitudinal axis of the shaft, characterized in that the end piece (3) has at least two differently designed surface designs on its support body, a closed surface (6 ') on a medial side (36) facing the neck part and a porous one Design (6) of the surface on the lateral side (38) facing away from the neck part.

2. Modular endoprosthesis according to claim 1, characterized in that the porous design (6) of the surface is designed as an open-line porous grid structure which is formed from a plurality of preferably regularly arranged unit cells (4).

3. Modular endoprosthesis according to claim 2, characterized in that the unit cells (4) are designed as a built structure and each of an interior (40) and a plurality of the interior (40) surround the interconnected webs (41, 42 , 43, 44).

4. Modular endoprosthesis according to one of the preceding claims, characterized in that the porous Gestal device (6) of the surface, in particular the open-line porous lattice structure, leads out unitary with the support body.

5. Modular endoprosthesis according to one of the preceding claims, characterized in that the porous Gestal device (6) is provided with a growth-promoting coating (45), in particular a coating with Tan talmaterial.

6. Modular endoprosthesis according to one of the preceding claims, characterized in that the porous Gestal device (6) extends from the lateral side (38) half-shell-like to the anterior and to the posterior side (35, 37).

7. Modular endoprosthesis according to one of the preceding claims, characterized in that a rounding with a lateral flattening (39) is provided at the transition between the lateral side (38) to the anterior side (35) and / or to the posterior side (37) is.

8. Modular endoprosthesis according to claim 7, characterized in that the rounding has a radius of curvature (r) which is at most a quarter of the distance (d) from the anterior to the posterior side of the support body (31).

9. Modular endoprosthesis according to claim 7 or 8, characterized in that the lateral flattening (39) is flat or has a minimum radius of curvature (R) of twice the distance (d) from the anterior to the posterior side of the support body (31) .

10. Modular endoprosthesis according to one of the preceding claims, characterized in that the support body has the porous design (6) of the surface exclusively on its lateral side (38).

11. Modular endoprosthesis according to claim 10, characterized in that the porous design (6) additionally extends to an upper side of the support body (31), but exclusively in a lateral area.

12. Modular endoprosthesis according to one of the preceding claims, characterized in that a lower loading area of the end piece (3) is free of the porous design (6).

13. Modular endoprosthesis according to one of the preceding claims, characterized in that a plurality of parallel through holes (8) are additionally provided in the lateral area, which extend from the anterior to the posterior side of the support body (31).

14. Modular endoprosthesis according to claim 13, characterized in that one or more through holes (8) open in the area with the porous design (6), and their respective mouths (80) are provided with a non-porous border (81) , which in turn are preferably completely surrounded by the porous design (6).

15. Modular endoprosthesis according to one of the preceding claims, characterized in that the porous Gestal device pores with a width in the range between 0.4 and

2 mm, preferably 0.7 to 1.5 mm.

16. Modular endoprosthesis according to one of the preceding claims, characterized in that it is a prosthesis sens system whose modular components (1, 2, 3) can be connected by means of matching connections (5), e.g. plug connections and rotation locks, and that there is also an exchange end piece (3 *) without a porous design and / or an exchange intermediate piece with a porous design (6 *) includes.