Implant System for Treating Bone Defects or Discontinuities

Abstract

The invention provides an implant system for treating bone defects or discontinuities and a method for producing such an implant system. The implant system (100) comprises: a first implant element (110) which is insertable or inserted into a bone defect or a discontinuity (2) of a human bone (1), a second implant element (120) which is fixable or fixed to the human bone (1), wherein the first implant element (110) is attachable or attached to the second implant element (120) by means of at least one biodegradable connection means (125) in order to fix the first implant element (110) relative to the human bone (1), wherein the first implant element (110) comprises a shell section (111) and an inner section (112) at least partially enclosed by the shell section (111), wherein the shell section (111) has a first pore-and-strut structure, PSS, and the inner section (112) has a PSS differing from the first PSS.

Claims

1. An implant system for treating bone defects or discontinuities, comprising: a first implant element configured for insertion into a bone defect or a discontinuity of a human bone, a second implant element configured to be fixed to the human bone, wherein the first implant element is attachable to the second implant element by means of at least one biodegradable connection means in order to fix the first implant element relative to the human bone, wherein the first implant element comprises a shell section and an inner section at least partially enclosed by the shell section, wherein the shell section has a first pore-and-strut structure, PSS, and the inner section has a second pore-and-strut structure, PSS, differing from the first pore-and-strut structure.

2. The implant system according to claim 1, wherein one of the first and second pore-and-strut structures has pore structures of greater than or equal to 200-700 micrometers in diameter.

3. The implant system according to claim 1, wherein one or both of the first and the second pore-and-strut structure has a gradient in the diameter of the pore structures.

4. The implant system according to claim 1, wherein the first implant element includes at least one biocomposite material.

5. The implant system according to claim 4, wherein one or both of the first and the second pore-and-strut structure has a gradient in a distribution of at least one biocomposite material.

6. The implant system according to claim 1, wherein the second implant element is nonbiodegradable.

7. The implant system according to claim 1, wherein the second implant element is in the form of a narrow reconstruction plate.

8. The implant system according to claim 1, wherein the shell section includes at least one polymer material.

9. The implant system according to claim 1, wherein the inner section includes at least one ceramic material.

10. A method for producing an implant system according to claim 1, comprising additive manufacturing of at least a portion of the first implant element.

11. The implant according to claim 2, wherein the other of the first and second pore-and-strut structures has pore structures of less than or equal to 150 micrometers in diameter.

12. The implant system according to claim 1, wherein the shell section includes at least one ceramic material.

13. The implant system according to claim 1, wherein the inner section includes at least one biocomposite material.

Description

BRIEF DESCRIPTION OF THE FIGURES

[0067] The invention will be more particularly elucidated below on the basis of exemplary embodiments in the figures of the drawings. Shown here by the partially schematized illustration are:

[0068] FIG. 1 a schematic three-dimensional view of an implant system according to one embodiment of the present invention;

[0069] FIG. 2 a schematic cross-sectional view through the implant system according to FIG. 1;

[0070] FIG. 3 a schematic three-dimensional view of an implant system according to a further embodiment of the present invention; and

[0071] FIG. 4 a schematic three-dimensional view of an implant system according to yet a further embodiment of the present invention.

[0072] In all the figures, identical or functionally identical elements and devices have been provided with the same reference signs, unless otherwise stated.

DETAILED DESCRIPTION OF THE FIGURES

[0073] FIG. 1 shows a schematic three-dimensional view of an implant system 100 according to one embodiment of the present invention. FIG. 1 depicts the situation of treating a discontinuity 2 as a result of insertion of the implant system 100 into a patient between two separate sections 1 of a long bone.

[0074] FIG. 2 shows the same situation in a schematic cross-sectional illustration.

[0075] The implant system 100 comprises a first implant element 110 which has been inserted into the discontinuity 2 after implantation. The first implant element 110 comprises a shell section 111 and an inner section 112 completely enclosed by the shell section 111. Alternatively, it is conceivable that the inner section 112 is directly adjacent to one or both of the interfaces to bone sections 1. In this case, the shell section 111 can also merely partially enclose the inner section 112, thus as a concentric cylindrical shell volume in the example depicted in FIG. 1.

[0076] The shell section 111 has a first pore-and-strut structure, PSS, and the inner section 112 has a second pore-and-strut structure differing from the first pore-and-strut structure. Possible here is a multiplicity of differences described in detail in the foregoing and in the following. For example, the first PSS and the second PSS can differ in their pore sizes, so that for instance the first PSS has a microstructure and the second PSS has a macrostructure, or vice versa.

[0077] The implant system 100 also comprises a second implant element 120 which is fixable to the human bone, in this case to both bone sections 1, and also fixed thereto in the situated depicted. The second implant element 120 can, for example, be in the form of a planar reconstruction plate and, as has already been described in detail in the foregoing, can, for example, consist of a nonresorbable material. Suitable therefor are, for example, titanium, chromium alloys, magnesium alloys, medical-grade steel and/or the like. When treating a discontinuity 2 which is comparatively easy to immobilize, such as a discontinuity 2 of a finger long bone, it may also be appropriate for the second implant element 120 to be composed of polyetheretherketone, PEEK, for example.

[0078] Fixation of the second implant element 120 to the bone, in particular to all separate bone sections 1 of the bone at respectively at least one site, is achieved by connection means 126. Said connection means 126 can, for example, be nonbiodegradable, so that the stability of the fixation of the second implant element 120 to the bone 1 is always maintained. However, the connection means 126 can also be biodegradable.

[0079] In contrast, the first implant element 110 is attachable to the second implant element 120, and also attached thereto in the situation in FIG. 1, by means of at least one biodegradable connection means 125. The first implant element 110 can thus be fixed relative to the human bone 1 without the need to establish direct fixation between the first implant element 110 and the human bone itself via a connection means. What is made possible by this is that, when selecting, designing and producing the first implant element 110, no account has to be taken of it being possible in some way for the regions of the first implant element 110 that are adjacent to the human bone 1 to accommodate connection means and to stably anchor them for a sufficient period of time.

[0080] Quite the contrary, the pore-and-strut structure, PSS, of the shell section 111 and that of the inner section 112 can therefore be fully directed at the optimal treatment of the discontinuity 2. As can be seen in FIG. 1 and FIG. 2, it is possible that the one or more connection means 125 between first implant element 110 and second implant element 120 mechanically connect and fix merely the second implant element 120 to the shell section 111 in a direct manner, but not the second implant element 120 to the inner section 112 in a direct manner.

[0081] Therefore, when designing the first pore-and-strut structure, PSS, of the shell section 111, account can still be taken of the necessary fixation to the second implant element 120, whereas when designing the second pore-and-strut structure, PSS, of the inner section 112, only the concerns of treating the discontinuity 2 can play a role. Fixation of the inner section 112 relative to the rest of the implant system 100 and relative to the human bone can therefore be achieved especially by a form fit, for example by the shell section 111 completely or at least partially enclosing the inner section 112, it also being possible for fixation of the inner section 112 to be ensured at least in part by the human bone itself, for instance by two-sided adjacency to opposing bone sections 1.

[0082] The distances between the implant elements 110, 120 from one another and from the human bone 1 are depicted in FIG. 1 and FIG. 2 in a highly exaggerated manner in order to be able to distinguish the individual parts from one another; in reality, the gaps, if present at all, are as small as possible. Preferred values and properties for the first pore-and-strut structure, PSS, of the shell section 111 were explained in detail in the foregoing.

[0083] FIG. 3 shows an implant system 200 according to a further embodiment of the present invention, again in a schematical three-dimensional view. The human bone 1 schematically depicted in FIG. 3 is also a long bone, for example of limbs or of ribs.

[0084] In contrast to the implant system 100, the first implant element 210 of the implant system 200 comprises two inner sections 212, 213 which are separate from one another and which are both completely enclosed by the shell section 211 of the first implant element 210. In the example depicted in FIG. 3, the two inner sections 212, 213 are substantially or exactly arranged flush with one another in a longitudinal direction, in which the long bone 1 also extends with the discontinuity 2 to be treated. In this example, the two inner sections 212, 213 are of the same size, but it will be appreciated that this does not need to be the case, that more than two inner sections 212, 213 can also be provided, that they do not have to be flush with one another in the longitudinal direction and/or and so forth.

[0085] As also in FIG. 1 and FIG. 2, the second implant element 120 of the implant system 200 is connected or attached to the first implant element 210 by means of two biodegradable connection means 225. Each of the biodegradable connection means 225 is adjacent to respectively one inner section 212, 213 of the first implant element 210 of the implant system 200 and can optionally also penetrate to some extent into the respective inner section 212, 213.

[0086] As also indicated in FIG. 3 by shading, the inner sections 212, 213 can each have a gradient in their respective pore-and-strut structure, PSS. The first inner section 212 indicates that a gradient (e.g., in pore size and/or in the ratio of the composition of at least two materials, in their density, etc.) extends in the longitudinal direction from one end of the first inner section 212 to the other end of the first inner section 212. By contrast, the second inner section 213 indicates that there is a gradient (again with regard to pore size, the ratio of material composition and/or the like) from the two outermost ends, as seen in the longitudinal direction, toward the middle of the second inner section 213. In the middle—again as defined in the longitudinal direction—of the second inner section 213, there can therefore be, for example, a material composition having increased strength (compared to the end and closing sections of the second inner section 213 in the longitudinal direction). As likewise indicated in FIG. 3, a biodegradable connections means 225 can interconnect not only the second implant element 120 and the shell section 211 but also precisely the middle of the second inner section 213. Whenever a gradient in pore size or strut width is provided, whichever is the other variable can accordingly also be provided with an opposite gradient, for example in such a way that a unit cell width of a cell composed of pore+surrounding strut structures remains the same size (with changing mass density).

[0087] In the case too of the first inner section 212, the mentioned gradient can at least also be a gradient in the strength, especially breaking strength, of the second inner section 213. In FIG. 3, it is again schematically depicted that the connection means 225 touches an outer end of the first inner section 212, which outer end is seen in the longitudinal direction and has said increased strength. Therefore, even within the inner section, functionally can additionally be specifically and locally adjusted via the inhomogeneous pore-and-strut structure, PSS.

[0088] In FIG. 3, it is also depicted that the second inner section 213 is fixed to the shell section 211 via—for example—three connection means 227 in the form of biodegradable pins.

[0089] Here, the pins can, for example, be introduced by ultrasound or be introduced in the form of screws. Specifically, the pins can have a diameter of 1, 1.5, 2 or 2.5 mm with a length of 0.9, 1.2, 1.4, 1.8 or 2.1 mm. Specific utilization of screw fixing in the longer length of the pins is also used, smaller elements of a length equal to or smaller than 1.5 mm are introduced by ultrasound. Preferred values and properties for the various pore-and-strut structures, PSS, of the shell section 211 and for the two inner sections 212, 213 of the inner section were explained in detail in the foregoing.

[0090] FIG. 4 shows a schematic three-dimensional illustration of an implant system 300 according to a further embodiment of the present invention.

[0091] The implant system 300 shown in FIG. 4 was, by way of example, used for treating a discontinuity 2 in a flat bone, for example a lower jaw or a cranial bone. In contrast to the implant systems 100; 200, in which the first implant element 110; 210 was roughly cylindrical, the first implant element 310 of the implant system 300 is roughly cuboid. The first implant element 310 also comprises two inner sections 312, 313 which are separate from one another and which are each arranged on an outer border of the inner section 311.

[0092] In the case of the embodiment shown in FIG. 4, the two inner sections 312, 313 are even each arranged at a different corner edge of the cuboid first implant element 310 and are each also cuboid themselves. Therefore, each of the two interfaces of the first implant element 310 with the bone 1 is formed partly by the shell section 311 and partly by an interface of a respective inner section 312, 313. Furthermore, in the case of the embodiment according to FIG. 4, it is also possible that each of the inner sections 312, 313 is directly adjacent to the second implant element 320. Accordingly, it is possible, for example, for each of the two inner sections 312, 313 to be directly connected to the second implant element 320 via a biodegradable connection means 325, which fixes them to one another, without the shell section 311 being passed through.

[0093] A further biodegradable connection means 325 can, in turn, fix the second implant element 320 to a portion of the inner section 311 that is arranged between the two inner sections 312, 313, without the connection means 325 touching any of the inner sections 312, 313. Therefore, each connection means 325 can be specifically chosen with regard to its material properties, etc., in such a way that it is appropriate for whatever is the connection situation. In particular, biodegradability over time can be specifically set. For example, it is possible that the middle connection means 325, which directly connects the second implant element 320 to the inner section 311, has lower biodegradability, that is to say it degrades more slowly, than the other two connection means 325 between the second implant element 320 and one of the two inner sections 312, 313.

[0094] In the case too of the embodiment of the implant system 300 shown in FIG. 4, it is schematically depicted that the inner sections 312, 313 each have a gradient, for example with regard to diameter of the pore structures, with regard to ratios of material compositions, with regard to density and/or with regard to further properties of the particular pore-and-strut structure, PSS. As indicated in FIG. 4, a gradient can, for example, extend from a side near the second implant element 320 toward a side of the respective inner section 312, 313 that is facing away from the second implant element 320. Alternatively or additionally, gradients along an extent of a longitudinal direction of the second implant element 320 are also conceivable, however. FIG. 4 also depicts, by way of example, further connection means 327, for example in the form of biodegradable pins, which can bring about fixation of each of the inner sections 312, 313 to the shell section 311. Therefore, the inner sections 312, 313 are not only mechanically fixed by means of the second implant element 320 or by means of the form fit of bone 1, shell section 311 and second implant element 320, but also additionally force-fittingly fixed to the shell section 311 in a direct manner.

[0095] The variants depicted in FIG. 1 to FIG. 3 for the respective second implant element 120 can, for example, be in the form of a 2-hole reconstruction plate. FIG. 4 shows an example in which the second implant element 320 is in the form of a 4-hole reconstruction plate. The second implant element 320 can also be biodegradable or nonbiodegradable, suitable materials in the latter case being especially titanium, medical-grade steel, magnesium alloys and/or chromium alloys and/or the like, though polyetheretherketone, PEEK, can also be used.

[0096] In the case of the implant system 300, what is inserted through each hole of the 4-hole reconstruction plate of the second implant element 320 is, by way of example, a cuboid connection means 326, for example a nondegradable one, in order to fixedly connect the second implant element 320 to the two sections of the human bone 1. This ensures a particularly good support of the entire implant system 300 on the bone 1, and the second implant element 320 can then, for example, be taken out again from the bone 1 when the connection means 325 have fully biodegraded and the support by the second implant element 320 for the first implant element 310 is no longer needed. Alternatively, the connection means 326 between the human bone 1 and the second implant element 320 can likewise be biodegradable. In this case, it is advantageous when the biodegradability of the connection means 325 between the second implant element 320 and the first implant element 310 is higher, that is to say that biodegradation occurs more rapidly, than biodegradability of the connection means 326 between the second implant element 320 and the human bone 1. This can ensure that the second implant element 320 does not detach from the bone 1 before it has detached from the first implant element 310, and so there is no need to fear that movement of the second implant element 320 will endanger the treatment of the discontinuity by the first implant element 310.

[0097] The first pore-and-strut structure, PSS, of the shell section 311 can, for example, have the following properties: pore size (e.g., pore diameter, pore side length) of 500 μm, strut structure diameter of 200 μm or greater, PDLLA-Ca—Mg biocomposite material composed of a mixture of calcium phosphate and magnesium phosphate having a mixture of A:B:C percent by mass, having a calcium phosphate gradient in percentage by mass, for example A=80, B=10, C=10 on the outer face (adjacent to the second implant element 320) of the shell section 311 and A=80, B=5, C=15 on the inner face (side facing away from the second implant element 320) of the shell section 311. Magnesium sulfate can preferably be applied as a coating to the inner face of the shell section 311, for example in order to achieve anitbacterial effects.

[0098] The second pore-and-strut structure of the first inner section 312 can, for example, have the following properties: pore size of 400 μm, strut structure diameter of 150 μm, and PCL material. The second pore-and-strut structure of the second inner section 313 (also referable to as third pore-and-strut structure) can, for example, have the following properties: maximum pore size of 300 μm, minimum strut structure diameter of 100 μm, PDLLA-CaCO.sub.3 biocomposite materials having a mixture of 72:18 percent by mass, gradient in the sense of a gradually (or stepwise) increasing strut structure diameter from 100 μm up to 300 μm from the outside (adjacent to the second implant element 320) to the inside with pore size concurrently becoming smaller in a converse manner.

[0099] The respective first implant element 110; 210; 310 containing the inner section 111; 211; 311 and the inner section(s) 112; 212; 213; 312; 313 can be produced by means of various additive manufacturing techniques.