TISSUE EXPANSION BOOSTER

Abstract

An implant (1) for modifying the tissue deformation during bone healing between two bone fragments (5; 6), with a first end piece (2) that can be fastened to a first bone fragment (5) with a longitudinal axis L1, and a second end piece (3) that can be fastened to a second bone fragment (6) with a longitudinal axis L2, wherein the first and second end pieces (2; 3) are loosely meshed with one another by means of n1 parallel-connected tissue activators (4a; 4b) in each case to allow relative movement and the tissue activators (4a; 4b) are arranged to be perpendicular to the longitudinal axes L1 and L2 and preferably orthogonal thereto.

Claims

1. An implant (1) for modifying the tissue deformation during bone healing between two bone fragments (5; 6) with (i) a first end piece (2) that can be fastened to a first bone fragment (5) with a longitudinal axis L1; (ii) a second end piece (3) that can be fastened to a second bone fragment (6) with a longitudinal axis L2; wherein a) the first and second end piece (2; 3) are loosely meshed with one another by means of n1 parallel-connected tissue activators (4a; 4b) in each case to allow relative movement; b) the tissue activators (4a; 4b) are arranged to be perpendicular to the longitudinal axes L1 and L2 and preferably orthogonal thereto.

2. The implant according to claim 1 wherein one or more spring elements (17) are arranged at least between two tissue activators (4a; 4b).

3. The implant (1) according to claim 1 or 2 wherein the implant (1) has a wrapping of essentially cylindrical or prismatic shape, and that a jacket that may surround the wrapping accounts for a maximum of 40%, preferably at most 20% of the total surface area of the wrapping.

4. The implant (1) according to claim 1 wherein the tissue activators (4a; 4b) are designed and arranged relative to one another in such a manner that they permit ingrowth of tissue.

5. The implant (1) according to claim 4 wherein the tissue activators (4a; 4b) may be plate-like, bar-like, mesh-like or rod-shaped.

6. The implant (1) according to claim 4 wherein the tissue activators (4a; 4b) are porous.

7. The implant (1) according to claim 1 wherein the opposing surfaces of the tissue activators (4a; 4b) are plane-parallel, curved or oblique.

8. The implant (1) according to claim 1 wherein the tissue activators (4a; 4b) consist of tissue-compatible plastics, metals, metal alloys or ceramic.

9. The implant (1) according to claim 1 wherein the tissue activators (4) consist of bioresorbable materials.

10. The implant (1) according to claim 1 wherein the surface of the tissue activators (4a; 4b) and/or the interstices between the tissue activators (4a; 4b) comprise substances that promote healing and bone building, preferably bone morphogenic protein or bone powder.

11. The implant (1) according to claim 1 wherein the surface of the tissue activators (4a; 4b) and/or the interstices between the tissue activators (4a; 4b) are provided with stem cells.

12. The implant (1) according to claim 1 wherein the interstices between the tissue activators (4a; 4b) are filled with an open-pore structure.

13. The implant (1) according to claim 1 wherein the first and second end pieces (2; 3) are designed such that they allow force-fit mechanical coupling to the two bone fragments, preferably (i) mechanically by press fitting, screwing, nailing, plating or sewing, or (ii) chemically by adhesive bonding.

14. The implant (1) according to claim 1 wherein the connection of the tissue activators (4a; 4b) with the end pieces (2; 3) is realised with individual or multi-part load-bearing elements (7a; 7b) and the load-bearing elements (7a; 7b) are firmly connected with a tissue activator (4a; 4b) or cross over these without contact.

15. The implant (1) according to claim 14, wherein the first end piece (2) is rigidly connected by one or more first load-bearing elements (7a) with the n1 first tissue activators (4a), and the second end piece (3) is connected by means of one or more second load-bearing elements (7b) with the n1 second tissue activators (4b).

16. The implant (1) according to claim 14 wherein the first end piece (2) is loosely, preferably movably, connected by means of one or more first load-bearing elements (7a) with at least one of the n1 first tissue activators (4a), and the second end piece (3) is loosely, preferably movably, connected by means of one or more second load-bearing elements (7b) with at least one of the n1 second tissue activators (4b).

17. The implant (1) according to claim 1, suitable for the treatment of bone fractures and bone defects and for growing bone tissue.

18. A method for modifying tissue deformation during bone healing between two bone fragments (5; 6) using an implant according to claim 1 wherein the tissue activators (4a; 4b) are activated outside the body of the patient.

19. The method according to claim 18, wherein the activation is performed in a tissue-penetrating, non-invasive manner.

20. The method for growing soft tissue or bone for therapeutic or aesthetic applications by means of an implant according to claim 1.

Description

[0056] The following is shown in the drawings:

[0057] FIG. 1 is a longitudinal section through an embodiment of the implant according to the invention;

[0058] FIG. 2 is a section along line A-A in FIG. 1;

[0059] FIG. 3 is a perspective view of the implant according to FIG. 1;

[0060] FIG. 4 is a schematic representation of the implant inserted between two bone fragments according to FIG. 1; and

[0061] FIG. 5 is a schematic representation of a further embodiment of the implant according to the invention.

[0062] The embodiment of the implant 1 according to the invention shown in FIGS. 1-3 comprises a first end piece 2, a second end piece 3 and several tissue activators 4a; 4b, which are alternatingly connected to one each of the end pieces 2; 3, wherein a first group of tissue activators 4a is arranged in a parallel connection and with the first end piece 2 forms a first component 10, which can be fastened to a first bone fragment 5, and a second group of tissue activators 4b is likewise arranged in a parallel connection and with a second end piece 3, forming a second component 11, which can be fastened to a second bone fragment 6. By alternately connecting the tissue activators 4a; 4b with the end pieces 2; 3, a parallel connection is achieved, which reduces the active distance over which the mutual movement of the adjacent bone fragments 5; 6 takes effect so that the expansion between the tissue activators 4a; 4b is increased. In particular, the implant 1 comprises a first end piece 2 with a longitudinal axis L1, which can be fastened to a first bone fragment 5, a second end piece 3 with a longitudinal axis L2, which can be fastened to a second bone fragment 6, and two groups of, as a non-limiting example, in each case four parallel tissue activators 4a; 4b, wherein each group of tissue activators 4a; 4b is connected with one each of the first and second end pieces 2; 3. The tissue activators 4a; 4b of each of the two groups are arranged at intervals from one another and alternately mesh with one another along a central axis 8 of the implant 8, in such a manner that the first and second end piece 2; 3 loosely mesh with one another, so that a relative movement of the first and second end pieces 2; 3 is guaranteed. The tissue activators 4a; 4b are arranged perpendicularly, and especially in the embodiment shown here, as a non-limiting example, orthogonal to the longitudinal axes L1 and L2 of the first and second end pieces 2; 3. The longitudinal axis L1 of the first end piece 2 and the longitudinal axis L2 of the second end piece 3 in the embodiment of the implant 1 according to the invention shown here are coaxially arranged and define a central axis 8 of the implant 1, which is likewise arranged coaxially to the longitudinal axes L1, L2.

[0063] The tissue activators 4a; 4b transfer the motion of the end pieces 2; 3 to the spaces between the tissue activators 4a; 4b mentioned and thus increase the expansion of the deformation produced by the movement of the end pieces 2; 3, which now, instead of the total distance between the end pieces 2; 3, takes place on the smaller distance between the tissue activators 4a; 4b. In this way the expansion of the material present between the tissue activators 4a; 4b is increased; the poorly healing bone fracture or -defect serves as an example. An increase in expansion of this type is decisive for bringing about healing of the bone defect or bone fracture.

[0064] Through serial connection of a spring element 17, reduction of the expansion between the tissue activators 4a; 4b [decreased expansion] can be attained. The spring element 17, as a non-limiting example, may be implemented as a coil spring, wound or folded element, in regular or free form.

[0065] Alternatively, only the end pieces 2; 3 may be connected with the respective packet of tissue activators 4a; 4b, but not reciprocally. The movement of the end pieces 2; 3 is then not reduced.

[0066] The first and second end piece 2; 3 are essentially formed such that they enable force-fit connection to one of the two bone fragments 5; 6 in each case, wherein the following couplings or combinations thereof are particularly suitable: (i) mechanically by means of press fitting, screwing, nailing, plating or sewing, or (ii) chemically by means of adhesive bonding.

[0067] FIG. 3 shows a perspective view of this embodiment of the implant 1 according to the invention obliquely from above. The load-bearing elements 7a; 7b are alternatingly connected with the tissue activators 4a; 4b or cross over these without connection. By way of example, the connection of the tissue activators 4a; 4b with the bone fragments 5; 6 is shown as a slotted sleeve, slotted tube or marrow nail, which permits press fitting. However, the implant 1 can also be inserted without connecting elements between the bone fragments 5; 6.

[0068] In the embodiment shown in FIG. 1-3, the first end piece 2, as a non-limiting example, comprises a longitudinal section 13 in the form of a slotted tube, which can be clamped firmly in the medullary cavity of the first bone fragment 5, and at the end of this longitudinal section 13 orthogonal to the longitudinal axis L1 is arranged an end plate 14 for attachment to the front face of the first bone fragment 5 facing the fracture gap. The tissue activators 4a of the first group and the first end piece 2 are connected together by means of first load-bearing elements 7a and form a first rigid component 10. Here, the end plate 14 of the first end piece 2 and the adjacent tissue activator 4a tissue activator and the tissue activators 4a of this first group, arranged at equal intervals to one another along the central axis 8 of the implant 1, as a non-limiting example, are connected by means of three first load-bearing elements 7a (FIG. 2).

[0069] In analogy to this, the second end piece 3 comprises a longitudinal section 15 in the form of a tube, which can be pressed over the outer surface of the second bone fragment 6, and arranged at the end of this longitudinal section 15, an end plate 16 for attachment to the front face of the second bone fragment 6 facing the fracture gap. The tissue activators 4b of the second group and the second end piece 3 are connected together by means of two load-bearing elements 7b and form a second rigid component 11. Here, the end plate 16 of the first end piece 3 and the adjacent tissue activator 4b tissue activator and the tissue activators 4b of this second group, arranged at equal intervals to one another along the central axis 8 of the implant 1, as a non-limiting example, are connected by three second load-bearing elements 7b (FIG. 2).

[0070] The first and second load-bearing elements 7a; 7b can be implemented as rods, clamps, or from other elements that rigidly connect the tissue activators 4a; 4b alternately with the first and second end pieces 2; 3. Thus, each of the first and second load-bearing elements 7a; 7b can be formed in one or more pieces. The load-bearing elements 7a; 7b extend essentially in parallel to the central axis 8 of the implant and are alternately firmly fixed on a tissue activator 4a; 4b or cross over this without contact. Alternatively, the load-bearing members 7a; 7b at the peripheries of the tissue activators 4a; 4b can be fastened to one group in each case and pass to the outside at the peripheries of the tissue activators 4a; 4b of the respective other group.

[0071] In the embodiment of the implant 1 according to the invention shown in FIG. 1-3, the end plates 14; 16 of the first and second end pieces 2; 3 and the tissue activators 4a; 4b are formed as plates with a polygonal periphery. As is apparent in FIG. 2, three load-bearing elements 7a; 7b per alternating packet of tissue activators 4a; 4b freely cross over the tissue activators 4a; 4b of the one packet and are connected firmly to the tissue activators 4a; 4b of the other packet. The load-bearing elements 7a; 7b of each component 10; 11 are, as a non-limiting example, arranged in a peripheral area of the tissue activators 4a; 4b, in each case at the angles of an equilateral triangle, wherein the first and second load-bearing elements 7a; 7b are at equal distances from one another. In this instance, the three load-bearing elements 7a of the first component 10 are firmly fixed on each tissue activator 4a of the first group, while the three load-bearing elements 7b of the second component 11 are passed through appropriately positioned holes 9 in each of the tissue activators 4a of the first group. Analogously, the three load-bearing elements 7b of the second component 10 are firmly fixed to each tissue activator 4b of the second group, while the three load-bearing elements 7a of the first component 10 are passed through appropriately positioned holes 9 in each of the tissue activators 4b of the second group. Alternatively, the tissue activators 4a; 4b may be bar-like, mesh-like or rod-shaped. The tissue activators 4a; 4b may be implemented as complete plates, but also as parts of plates, e.g., plate segments or other regular or irregular shapes, wherein the plate parts can be parts of a plate, located adjacent to one another, arranged in staggered form or networked.

[0072] Since both components 10; 11 are rigidly constructed, i.e., the tissue activators 4a; 4b of each of the two groups are firmly fixed to the corresponding end piece 2; 3, a load, for example applied to the first bone fragment 5, will be transferred over the first end piece 2 as a compressive force onto the first component 10 with the tissue activators 4a of the first group, so that the distance between the end plate 14 of the first end piece 2 and the terminal tissue activator 4b of the second component 11 is shortened, and a negative extension or compression of the bone material located between them takes place. On the other hand, the distance is increased between the terminal tissue activator 4b of the second component 11 and the first tissue activator 4a of the first component 10, i.e., the tissue activator 4a of the first group, which is adjacent to the first end piece 2, so that a positive expansion of the one elongation of the bone material located in between takes place if this is fixed on the tissue activators 4a; 4b.

[0073] In various embodiments of the implant 1 according to the invention, the tissue activators 4a; 4b may be porous. In addition, the opposing surfaces of the tissue activators 4a; 4b may be of plane-parallel, curved or oblique design, wherein the surfaces may be arched or curved in various ways, so that the interval between pairs of tissue activators 4a; 4b changes from place to place and, for example, generates sites of optimal expansion. The tissue activators 4a; 4b are made of tissue-compatible plastics, metals, metal alloys or ceramic, or may also consist of bioresorbable materials.

[0074] The surfaces of the tissue activators 4a; 4b and/or the interstices between the tissue activators 4a; 4b comprise substances (not shown) that promote healing and bone building, preferably bone morphogenic protein or bone powder. In another embodiment, the surfaces of the tissue activators 4a; 4b and/or the interstices between the tissue activators 4a; 4b may be provided with stem cells to promote healing and bone formation. Alternatively, or additionally, the interstices between the tissue activators 4a; 4b may be filled with an open-pore structure.

[0075] The implant 1 according to the invention shown in FIG. 4 in this example serves to replace a poorly healing or non-healing segment of a long bone 18, e.g., a femur, between a first and a second bone fragment 5; 6. Other applications are not bound to this example of the cortical long bone. The implant 1 according to the invention can also be used in cancellous bone and in bone defects. The tissue differentiation created by optimising the expansion not only applies to that of the bone but also to the differentiation of the soft tissue.

[0076] The embodiment of the implant 1 according to the invention shown in FIG. 5 differs from the embodiment shown in FIG. 1-3 only in that the implant 1, as a non-limiting example, comprises only one tissue activator 4a, 4b per group, i.e., per component 10; 11, and that spring elements 17 are inserted between the tissue activators 4a; 4b. As described above, the optimal tissue expansion falls within the range between expansion that is too small, which does not induce healing, and excessive expansion, which does not enable bridging of the fracture by callus formation. Solid healing is prevented by the latter. The implant 1 according to the invention enables an increase in the case of expansion that is too small, and as a result of the spring element 17 of the embodiment shown in FIG. 4, also enables reduction of an excessive expansion. As a non-limiting example, two spring elements 17 are inserted between the tissue activators 4a; 4b. Alternatively, other elastically deformable elements may also be used.

[0077] Through the spring elements 17, a load acting on the bone fragments is opposed by an additional but very small resistance. The spring elements 17 serve for distributing the expansion and have no supporting function. To create areas that are subjected to different expansions, it is provided that the surfaces of the activators 4a; 4b may be made curved and not plane-parallel. The tissue activators 4a; 4b can be connected to the load-bearing elements 7a; 7b rigidly or non-rigidly, i.e., movably. For example, terminal stops may be arranged on the load-bearing elements 7a; 7b, so that the tissue activators 4a; 4b remain connected to the load-bearing elements 7a; 7b.

[0078] As mentioned above, the optimal tissue deformation (expansion) falls within a range between expansion that is too small, at which healing is not induced, and excessive expansion, which does not enable bridging of the fracture by callus formation. The latter does not provide for solid healing. The implant according to the invention makes it possible to increase an expansion that is too small, but is also suitable for reducing excessive expansion based on the following modification:

[0079] Spring-like elements or spring elements 17 are introduced between the tissue activators 4a; 4b. Along these spring elements 17, which considerably increase the distance between the tissue activators 4a; 4b, the tissue is subjected to reduced deformation, since for this movement the distance over which the tissue is deformed is increased several-fold. In this way the size of the tissue deformation is reduced. The effect of this increase in the distance because of the use of spring elements 17 is several-fold larger than the effect of a shorter distance between the tissue activators 4a; 4b, which would increase the expansion. Thus, in an implant 1, areas of larger expansion (directly connected between the tissue activators 4a; 4b) and areas of lesser expansion are established along the spring elements 17.

[0080] The tissue, which undergoes optimal expansion, either between the tissue activators 4a; 4b or along the spring elements 17, enables healing, wherein it is not necessary for correct functioning that the same expansion conditions be present overall. Healing begins in the areas with optimal expansion, and the subsequent solid bridging reduces the displacement between the ends of the fragments or between the ends of the implant 1, so that healing over the entire cross-section becomes possible.

[0081] Although various embodiments of the present invention exist, as described above, these are to be understood as meaning that the various features can be used individually and also in any arbitrary combination.

[0082] Therefore, this invention is not simply limited to the particularly preferred embodiments mentioned above.