Abstract
An implant (X) for replacing or filling a defect of a flat bone has a flat shape with a first side (X1) and an opposite second side (X2). The implant (X) includes a first layer (S1) formed of non-porous polyetheretherketone or polyethylene, which has such a layer thickness that the shape of the implant (X) is established by the shape of the first layer (S1). The implant (X) includes, in at least some portions on the first side (X1), a second layer (S2) formed of a porous polymer which is not polyaryletherketone or polyetheretherketone. A method for producing such an implant (X) is also provided.
Claims
1-16. (canceled)
17. An implant (X) for replacing or filling a defect of a flat bone, the implant (X) having a flat shape with a first side (X1) and an opposite second side (X2), the implant (X) comprising: a first layer (S1) formed of non-porous polyetheretherketone or polyethylene, the first layer (S1) having a layer thickness such that a shape of the implant (X) is established by a shape of the first layer (S1); and in at least some portions on the first side (X1), a second layer (S2) formed of a porous polymer that is not polyaryletherketone or polyetheretherketon.
18. The implant (X) of claim 17, wherein the implant (X) does not comprise a metal support structure.
19. The implant (X) of claim 17, wherein the second layer (S2) is formed entirely or predominantly of polyethylene, polyphenylene sulfone, or polypropylene.
20. The implant (X) of claim 19, wherein one or both of the first layer (S1) and the second layer (S2) is formed of ultra-high molecular weight polyethylene.
21. The implant (X) of claim 17, wherein the second layer (S2) is a pressed and fused granular layer.
22. The implant (X) of claim 17, wherein a further layer is not arranged on the second side (X2) of the implant (X) such that the first layer (S1) is exposed.
23. The implant (X) of claim 17, further comprising a third layer (S3) on the second side (X2) of the implant (X), the third layer (S3) formed of the same material as the second layer (S2).
24. The implant (X) of claim 23, wherein a porosity and/or a surface roughness of the third layer (S3) differs from a porosity and/or a surface roughness of the second layer (S2).
25. The implant (X) of claim 17, wherein at least a portion of the first layer (S1) is not covered by a further layer (S2, S3).
26. The implant (X) of claim 17, wherein the first layer (S1) is disposed over an entire surface of the second side (X2) or is formed by interconnected strips (S1B).
27. The implant (X) of claim 17, wherein the first layer (S1) defines at least one through-opening (A).
28. The implant (X) of claim 17, wherein at least one recess (Z) for accommodating a fixing element (MP) is formed in the first layer (S1) and/or in the second layer (S2).
29. The implant (X) of claim 17, wherein at least one of the layers (S1, S2, S3) of the implant (X) is enriched with: silver; strontium; magnesium; tricalcium phosphate; hydroxyapatite; molybdenum; calcium carbonate; or combinations thereof.
30. The implant (X) of claim 17, wherein the implant (X) is a cranial implant (CX).
31. The implant (X) of claim 17, wherein the implant (X) is an eye socket implant (OX).
32. A method for producing the implant (X, CX, OX) of claim 17, comprising: providing a fully formed first layer (S1); activating at least a portion of a surface of the first layer (S1) with low pressure plasma; and applying the second layer S2 onto the activated surface of the first layer (S1) by pressing on and fusing a granular material.
Description
BRIEF DESCRIPTION OF THE DRAWINGS
[0025] Exemplary embodiments of the invention are described in detail on the basis of the figures. Wherein:
[0026] FIG. 1 and FIG. 2 each show a view of an implant according to a first exemplary embodiment;
[0027] FIG. 3 and FIG. 4 each show a detailed view of the implant according to the first exemplary embodiment;
[0028] FIG. 5 shows a schematic side view of an implant according to a second exemplary embodiment;
[0029] FIG. 6 shows a schematic isometric view of an implant according to a third exemplary embodiment;
[0030] FIG. 7 shows a schematic top view of an implant according to a fourth exemplary embodiment;
[0031] FIG. 8 shows a schematic top view of an implant according to a fifth exemplary embodiment; and
[0032] FIG. 9 shows a schematic top view of an implant according to a sixth exemplary embodiment.
DETAILED DESCRIPTION
[0033] Reference will now be made to embodiments of the invention, one or more examples of which are shown in the drawings. Each embodiment is provided by way of explanation of the invention, and not as a limitation of the invention. For example, features illustrated or described as part of one embodiment can be combined with another embodiment to yield still another embodiment. It is intended that the present invention include these and other modifications and variations to the embodiments described herein.
[0034] FIG. 1 and FIG. 2 each show a view of an implant X according to a first exemplary embodiment. The implant X is suitable for replacing or filling a defect of a flat bone. The first exemplary embodiment of the implant X shown in FIG. 1 and FIG. 2 is intended for use in the cranium, for example, as a cranial implant CX. The implant X has a flat curved shape with a first side X1 and an opposite second side X2. The implant X has a first layer S1 formed of a non-porous polyetheretherketone or non-porous polyethylene, preferably formed of ultra high molecular weight polyethylene. On the first side X1, the implant X has a second layer S2 formed of a porous polymer, which is attached on the first layer S1. The second layer S2 is formed entirely or predominantly of polyethylene, polyphenylene sulfone or polypropylene, particularly preferably of ultra-high molecular weight polyethylene (UHMWPE). The first layer S1 is so thick that it is not possible to shape the implant X during surgery. In other words, the first non-porous layer S1 is so thick that the first layer S1 is dimensionally stable, such that the first layer S1 cannot be plastically deformed to adapt the implant geometry without damaging the second porous layer S2. The minimum wall thickness of the first layer S1 necessary for this mechanical behavior depends on the size and shape of the implant X. In the example shown in FIG. 1, the implant X is approximately ten centimeters (10 cm) long and ten centimeters (10 cm) wide, and has a curved surface shape. If the first layer S1 is produced from polyetheretherketone or ultra-high molecular weight polyethylene, the wall thickness of the first layer S1 is two millimeters (2 mm) to four millimeters (4 mm) on average given this geometry. Depending on the mechanical load on the implant X, the first layer S1 can also have a greater mean wall thickness, for example, six millimeters (6 mm).
[0035] The second layer S2 is present in a pressed and fused granular form. As a result, a homogeneous porosity of the second layer S2 combined with high resistance to superficial damage is obtained. Due to the homogeneous porosity, an ingrowth of tissue into the second layer S2 is made possible, whereas, due to the non-porous design of the first layer S1, an ingrowth of tissue into the first layer S1 is prevented.
[0036] FIG. 3 and FIG. 4 each show a detailed view of the implant X according to the first exemplary embodiment. In order to produce such an implant X, initially the first layer S1 is produced, for example, by a forming press or by a generative/additive manufacturing process, also known as 3D printing. In particular by using a generative manufacturing process, the first layer S1 can be produced precisely according to the individual needs of a patient. Then the first layer S1 is reworked if necessary, in order to remove burrs or supporting structures from the preceding production step. At least a portion of the first layer S1 is subsequently activated by using a low pressure plasma to generate a particularly adhesive surface. Immediately thereafter, the second layer S2 is applied onto the previously activated surface of the first layer S1, specifically by pressing on and fusing a granular material. In this way, the second layer S2 can be securely applied onto the first layer S1 without the need for an additional adhesive or the like.
[0037] It becomes clear from the illustration according to FIG. 3 that the second layer S2 can be considerably thinner than the first layer S1. FIG. 4 shows an example embodiment in which the second layer S2 is as thick as the first layer S1.The specific thickness of the porous second layer S2 can be selected according to the intended use and the specific needs of the patient. The second layer S2 can have an inhomogeneous layer thickness, such that a thicker second layer S2 is present at one point of the implant X than at another point. A thickness of the second layer S2 between one millimeter (1 mm) and six millimeters (6 mm) has proven advantageous in tests. A typical overall thickness of the implant X having a two-layer structure with a first layer S1 and a second layer S2 is four millimeters (4 mm) to eight millimeters (8 mm).
[0038] The representation of the porous second layer S2 in the figures is abstracted, since a representation of the actual porosity in patent drawings is not reliably recognizable and reproducible.
[0039] FIG. 5 shows a schematic side view of an implant X according to a second exemplary embodiment. In this example embodiment, the implant X has a porous layer both on the first side X1 and on the opposite second side X2. To this end, the second layer S2 is arranged on the first side X1, whereas a third layer S3 is arranged on the second side X2. The third layer S3 is made of the same material as the second layer S2. However, the third layer S3 has a different porosity than the second layer S2, as is indicated in the illustration according to FIG. 5. The different porosity is achieved by using a different granule size. The first layer S1 lies between the second layer S2 and the third layer S3, so that the implant X has a three-layer sandwich structure.
[0040] FIG. 6 shows a schematic isometric view of an implant X according to a third exemplary embodiment. In this example embodiment, multiple portions of the first layer S1 are not covered by a further layer, such that portions of the first layer S1 are exposed on both sides X1, X2 of the implant X. On the first side X1, only two strips of the second layer S2 are applied on the first layer S1. The second layer S2, which is arranged in a strip-shaped manner, has a thin wall, for example, with a layer thickness of only one millimeter (1 mm). A through-opening A is provided in a portion of the first layer S1 that is not covered on either side. Due to the through-opening, an exchange of fluid and pressure compensation between the first side X1 and the second side X2 are made possible in the implanted state. The implant X can have multiple such through-openings A.
[0041] FIG. 7 shows a schematic top view of the second side X2 of an implant X according to a fourth exemplary embodiment. In this example embodiment, the first layer S1 has a peripheral edge S1R and multiple interconnected strips S1B. The first layer S1 has multiple voids between the strips S1B. In contrast to the exemplary embodiments shown in FIG. 1 through FIG. 6, the first layer S1 is therefore not formed over the entire surface. The second layer S2 is arranged on the first side X1 (not visible in FIG. 7) of the implant X and is also visible from the second side X2 through the voids in the first layer S1. In this example embodiment, the second layer S2 is therefore accessible from both sides in some portions. In such an example embodiment, a third layer S3 formed of a porous polymer can be arranged on at least some portions of the second side X2, as is schematically shown in FIG. 5. For the sake of clarity, such an example variant is not explicitly shown in the figures.
[0042] FIG. 8 shows a schematic top view of an implant X according to a fifth exemplary embodiment. A recess Z, which is designed to accommodate a fixing element MP, is provided on the edge of the implant X. The fixing element MP can be, for example, a metal plate that has a hole for accommodating a fastening screw or a strand of suture. The implant X can have multiple such fixing element MP, which are arranged in multiple recesses Z distributed on the edge of the implant X.
[0043] FIG. 9 shows a schematic top view of the second side X2 of an implant X according to a sixth exemplary embodiment. The implant X is in the form of an eye socket implant OX. A third layer S3 formed of a porous polymer is arranged on a portion of the second side X2. The non-porous first layer S1 is exposed on the edge region of the implant X, i.e., is not covered by a porous layer. The second layer S2 is formed on at least some portions of the first side X1 (not visible in FIG. 9).
[0044] Modifications and variations can be made to the embodiments illustrated or described herein without departing from the scope and spirit of the invention as set forth in the appended claims. In the claims, reference characters corresponding to elements recited in the detailed description and the drawings may be recited. Such reference characters are enclosed within parentheses and are provided as an aid for reference to example embodiments described in the detailed description and the drawings. Such reference characters are provided for convenience only and have no effect on the scope of the claims. In particular, such reference characters are not intended to limit the claims to the particular example embodiments described in the detailed description and the drawings.
LIST OF REFERENCE SIGNS
[0045] X implant [0046] CX cranial implant [0047] OX eye socket implant [0048] X1 first side [0049] X2 second side [0050] S1 first layer [0051] S1B strip [0052] S1R edge [0053] S2 second layer [0054] S3 third layer [0055] A through-opening [0056] Z recess [0057] MP fixing element
