Implant for securing skull flap in cranial opening of bone skull

Abstract

The invention relates to an implant for fixing a skull flap in a cranial opening of a bone skull, having a flexible network structure with bridges and openings formed between the bridges, the flexible network structure being made of a plastic material and being designed to be fastened to the skull flap and to the bone skull.

Description

Technical Field

[0001] The present invention relates to an implant for fixing a skull flap in a cranial opening of a bony skull. Background Art

[0002] Neurosurgery at the brain is usually performed through an opening in the bony skull. Creating such a cranial opening is also known as a craniotomy. In the case of a craniotomy, a portion of the skull is separated from the bony skull by trephination and usually with the help of a craniotomy knife. The separated portion is also known as a bone flap or bone fragment. After the operation is performed, the bone flap is repositioned and fixed in the previously created cranial opening.

[0003] Implants in the form of so-called clamp systems are known for fixing bone flaps. For example, a clamp system from Aesculap AG of Tuttlingen, Germany, called 2. The known clamp system has an upper dish element, a lower dish element and a rod element that movably connects the two dish elements to each other. In order to fix the bone flap, the lower dish element is first placed on the skull cap. The upper dish element is brought close to the lower dish element along the rod element and pressed into the final position with a defined force. In the final fixed state, the two dish elements are firmly pressed against the outer side of the bone flap and the surrounding skull bone in the axial direction of the cranial opening, and against the inner side of the bone flap and the surrounding skull bone in the axial direction of the cranial opening.

[0004] With regard to the known clamp systems, various aspects can be considered disadvantageous: the arrangement of the lower dish element in the epidural space can under certain conditions lead to irritation of the dura mater or even to epidural hematomas. Axial tensioning of the disc element carries the risk of inadvertently applying pressure to the dura. 2, a separate tool is provided for holding the rod element. The additional tool required can make the operation more difficult. In addition, the dish element remains permanently at the patient's skull after fixation has been achieved. This is particularly disadvantageous in cases where the upper dish element is located in an aesthetically critical area, such as in the case of a frontal craniotomy. Since the upper and lower dish elements must rest as flat as possible on the skull and the bone flap for satisfactory fixation, fixation is generally not possible or unsatisfactory in cases of strong curvatures or thickness gradients. In addition, strong curvatures can cause the upper dish element to protrude from the outside of the skull, which can lead to a poor cosmetic effect and / or scalp irritation. Summary of the invention

[0005] The object of the present invention is to provide an implant of the type mentioned at the outset which offers advantages over the prior art. In particular, the disadvantages associated with the prior art should be at least partially overcome or reduced.

[0006] This object is achieved by providing an implant having the features of claim 1. Advantageous embodiments are the subject matter of the dependent claims, the wording of which is incorporated into the content of the description by explicit reference.

[0007] The implant according to the present invention has a flexible network structure with a bridge and an opening formed between the bridges, wherein the flexible network structure is made of a plastic material and is set up for fastening to a bone flap and a bony skull. Improved medical and cosmetic effects can be achieved by the solution according to the present invention and particularly simple application and correction can also be achieved. The flexible network structure extends over a large area and therefore has a smaller thickness than conventional clamp systems and the like. Since the flexible network structure is not very noticeable under the patient's scalp, a relatively small thickness allows for improved cosmetic effects. Thus, the implant according to the present invention can preferably be used in the aesthetically critical area of ​​the skull, for example in frontal craniotomy. Since the network structure is flexible, its shape can be particularly easily adapted to the patient's given skull geometry. The protrusion of the implant is also avoided in the strongly curved convex or concave skull area. On the one hand, irritation of the scalp is also avoided by a thin and flexible design at the same time. This is advantageous in medical terms. The flexible and thin design combined with the production of the plastic material also allows for particularly easy application by surgeons. For example, the flexible network structure can be easily and with simple tools, such as scissors or scalpels, cut into sizes and geometries suitable for corresponding craniotomies, thereby achieving a simplified and particularly versatile application. This is different from known implants made of metal, which usually have to be provided in different sizes and / or geometries and do not allow simple size matching and / or geometry matching by the end user. The flexible network structure is set up for fastening at the bone flap and the bony skull, wherein the fastening can be carried out in a material-matched manner by means of an adhesive suitable for this or in a form-fitting and / or force-fitting manner by means of a fastening element suitable for this. For fastening, the flexible network structure is applied and fixed to the outside of the skull and / or the outside of the bone flap. Accordingly, it is easy to remove the implant for modification purposes. In particular, no special instrument is required for this. If the flexible network structure should be glued, it can be removed from the bone flap and the bony skull in order to be modified in the manner of plaster. In a design, the bridge and / or opening of the network structure are regularly arranged, in particular at regular intervals and / or in a regular pattern. In another design, the bridge and / or the opening are arranged irregularly. In one design, the opening has an opening width of 2 μm to 5 mm. In another design, the openings have an opening width in the range of 2 μm to 1 mm, respectively. In another design, the openings have an opening width in the range of 2 μm to 20 μm, respectively. In one design, the plastic material is at least partially absorbable, preferably fully absorbable. In another design, the plastic material is non-absorbable. The plastic material is biocompatible. Biocompatible plastics for medical applications are known to those skilled in the art. In one design, the implant is composed of a flexible network structure.In a further embodiment, the implant has a multi-layer structure, wherein the flexible network structure forms a layer of the multi-layer structure.

[0008] In the design of the invention, the flexible surface structure is translucent. In other words, the flexible network structure is transparent. This avoids artifacts when using imaging methods. If the flexible network structure is designed to be bonded to the bone flap and the bony skull surrounding the cranial opening in a material-fitting manner, the translucent property allows the use of radiation-induced hardening adhesives.

[0009] In a further embodiment of the invention, the flexible network structure has a thickness of 0.2 mm to 0.5 mm. On the one hand, this allows a particularly good cosmetic effect to be achieved, since the flexible network structure does not appear under the patient's scalp or appears practically unrecognizable under the patient's scalp due to its low thickness. On the other hand, a thickness within the stated value range ensures adequate mechanical properties.

[0010] In another embodiment of the present invention, the flexible network structure is isotropically elastic. Isotropic elasticity means that the flexible network structure has elastic properties that are independent of direction in the extended plane of its face shape. Thus, the flexible network structure can be adapted to the given skull geometry of the patient in an improved manner during application.

[0011] In another embodiment of the present invention, the bridges are arranged crosswise without knots, and the flexible network structure is constructed in the form of a knitted fabric or a fabric. Knotless means that the bridges of the flexible network structure do not have intersections that are firmly connected to each other. As a result, the flexible network structure can be particularly easily matched to the given shape of the bone flap and the surrounding bony skull. This simplifies the application of the implant again. In this embodiment, the flexible network structure is a knitted fabric or a fabric. Alternatively, it is conceivable to manufacture it with the help of electrospinning or additive manufacturing processes. In an alternative design, the bridges are firmly connected to each other at their corresponding intersections. As a result, simplified cutting can be achieved in particular. The collapse of the flexible network structure is avoided.

[0012] In another embodiment of the present invention, the plastic material comprises polypropylene and / or polyglycolic acid. The inventors have recognized that this can be accompanied by specific advantages. Due to their good biocompatibility, polypropylene and polyglycolic acid have been used in the manufacture of medical suture materials. This shows its good applicability from a mechanical point of view. Although polypropylene is not absorbable, polyglycolic acid can be hydrolyzed and absorbed by the human body within approximately 60 to 90 days. In addition, polypropylene has transparent properties, which can simplify implantation. Polylactic acid groups, especially polylactic acid groups with transparent properties, can be alternatively or additionally a component of the plastic material. In other designs, it is conceivable that plastics of natural origin, such as cellulose, silk, fibroin, gelatin or collagen, mixed with polypropylene and / or polyglycolic acid, are particularly used to promote biocompatibility.

[0013] In a further embodiment of the invention, the plastic material contains non-metallic additives, preferably glass fibers and / or ceramic particles. The additives can increase the mechanical strength and / or the bone integration.

[0014] In another embodiment of the present invention, the implant has at least one medical active ingredient, which is applied to the flexible network structure in the form of an active ingredient coating and / or introduced into the opening in the form of an active ingredient filler. Alternatively or additionally, it can be mentioned that the medical active ingredient is applied to the network structure and / or introduced into the network structure. Medical active ingredients are, for example, antibiotics, analgesics, growth factors, etc. The surface extension of the flexible network structure avoids local excessive active ingredient concentrations and enables particularly advantageous release of active ingredients. In particular, improved regeneration of the periosteum can be achieved. In one embodiment, the medical active ingredient is applied to the flexible surface structure in the form of the active ingredient coating, in particular to its underside and / or upper side. In another embodiment, the medical active ingredient is alternatively or additionally introduced into the opening of the flexible network structure in the form of an active ingredient filler.

[0015] In another design of the present invention, the implant has an adhesive, which is applied to the flexible network structure in the form of an adhesive layer and / or is brought into the opening in the form of an adhesive filler. In this design of the present invention, the use of a separate adhesive product and / or a separate fastening element can be omitted. The adhesive is a component of the implant in the form of an adhesive layer and / or an adhesive filler. In one design, the adhesive is at least partially absorbable, preferably fully absorbable. In another design, the adhesive is non-absorbable. All biocompatible and suitable adhesives for medical applications can be used. Such adhesives are known to those skilled in the art. If the implant should have a medical active ingredient according to the aforementioned design, it can be integrated into the adhesive layer and / or the adhesive filler. On the one hand, the adhesive is used to fasten the flexible network structure to the bone flap and the surrounding bone skull. On the other hand, the adhesive is used to mechanically stabilize the flexible network structure. Preferably, the adhesive is set up to harden by means of UV radiation. Alternatively or additionally, other hardening mechanisms can be envisioned, for example, by moisture, heat or other physical and / or chemical mechanisms of action.

[0016] In a further embodiment of the invention, the adhesive is a medical textile adhesive which hardens under the influence of UV radiation. The inventors have recognized that such an adhesive offers particular advantages in conjunction with the present application.

[0017] In another embodiment of the present invention, the implant has at least one removable first protective layer, which is at least indirectly applied to the lower side of the flexible network structure, and / or a removable second protective layer, which is at least indirectly applied to the upper side of the flexible network structure. The first protective layer and / or the second protective layer are removed and thus removed before the implant is implanted. The first protective layer is used to protect the lower side of the flexible network structure. The second protective layer is used to protect the upper side of the flexible network structure. If the flexible network structure does not have an active ingredient layer, an adhesive layer and / or other layers at its lower side and / or upper side, the first protective layer and / or the second protective layer are directly applied to the flexible network structure. Otherwise, the corresponding protective layer only indirectly covers the flexible network structure and is directly applied to one of the layers. The first protective layer and / or the second protective layer are preferably particularly smooth protective films. The protective film is preferably made of a plastic material suitable for this, for example, made of PTFE.

[0018] The invention also relates to a kit having an implant according to any one of claims 1 to 8 and having an adhesive which is configured to bond a flexible network structure to a bone flap and a bony skull. In this design of the invention, the adhesive is provided as a separate product and, together with the implant, forms a kit for fixing a skull flap. For the purpose of fastening the flexible network structure, the adhesive is applied to its underside and / or upper side prior to actual application. Adhesives suitable for this are known to those skilled in the art. In one design, the adhesive is a spray adhesive which can be sprayed onto the flexible network structure.

[0019] The present invention also relates to a kit having an implant according to any one of claims 1 to 8 and having a plurality of fastening elements, which are configured to fasten a flexible network structure to a bone flap and a bony skull in a force-fitting and / or form-fitting manner. In one design, the plurality of fastening elements are pins. Alternatively, the fastening elements can be screws, hooks, etc. In one design, the pins can be degraded using pre-drilled holes. In another design, the pins are non-degradable and self-tapping. Prior to the actual application of the implant, the fastening elements are inserted into the outer side of the bone flap and into the bony skull surrounding the cranial opening. The inserted fastening elements form an anchoring point for the flexible network structure, which can be hooked and tensioned to the fastening element by means of its opening. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Further advantages and features of the invention emerge from the claims and from the following description of preferred embodiments of the invention presented with the aid of the drawings.

[0021] Figure 1 The head of a patient is shown in a schematic, greatly simplified perspective view, wherein the bony skull has a cranial opening closed with a bone flap,

[0022] Figure 2 The region of the cranial opening in which the bone flap is fixed by means of an embodiment of the implant according to the invention is shown in a schematic top view.

[0023] Figure 3 The area of ​​the cranial opening is shown in a schematic simplified cross-sectional view,

[0024] Figure 4 The perspective exploded view shows the state in which two protective films are provided according to Figure 2 and Figure 3 implants,

[0025] Figure 5 The schematic diagram, which is greatly simplified, shows the Figure 4 A cross section of the layer structure of the implant,

[0026] Figure 6 A schematic diagram shows an embodiment of the kit according to the invention,

[0027] Figure 7 A further embodiment of the kit according to the invention is shown schematically, and

[0028] Figure 8 Corresponding to Figure 3 The diagram shows the use of Figure 7 Example application scenarios of the kit. DETAILED DESCRIPTION

[0029] according to Figure 1 The patient's head has a cranial opening B. The cranial opening B extends from the outer side of the skull CA through the patient's bony skull C to the inner side of the skull CI (see Figure 3 ). The cranial opening B extends axially through the bony skull C and is bounded radially by the bony skull.

[0030] The cranial opening B may be substantially caused by an accident or other trauma. In the present case, the cranial opening B is the result of a craniotomy and serves as a surgically created channel for performing neurosurgery at the patient's brain.

[0031] In such a craniotomy, the bony skull C is opened by mechanically separating the bone flap D. This can be done, for example, with the aid of a trephine and a craniotome. Here, the bone flap D is separated from the bony skull C while forming an annular gap S. The annular gap S is also referred to as a craniotomy gap. The bone flap D can also be referred to as a bone part, a bone fragment or a bone segment.

[0032] After the bone flap D has been separated, it can be temporarily removed from the remaining bony skull C while the actual cranial opening B is constructed. After the operation at the brain, the bone flap D is repositioned and fixed in the opening B.

[0033] according to Figure 2 , an implant 1 for fixing a skull flap D in a skull opening B is provided. The implant 1 has a flexible surface structure 2, which has bridges 3 and an opening 4 formed between the bridges. In addition, the flexible surface structure 2 is made of a plastic material K and is set up to be fastened at the skull flap D and at the bony skull C bordering the opening B in a manner that will be described in more detail.

[0034] In accordance with Figure 2 and Figure 3In the case shown, the flexible network structure 2 spans the bone flap D, the annular gap S and the area around the opening B of the bony skull C. Here, the flexible network structure 2 is located on the outer side DA of the bone flap D and on the outer side CA of the bony skull C. The fastening of the flexible network structure 2 on the one hand to the bone flap D and on the other hand to the bony skull C is different in different designs and can be achieved, for example, by means of an adhesive suitable for this and / or by material bonding using suitable fastening elements.

[0035] Especially in Figure 2 The arrangement of the bridges 3 and / or openings 4 shown in the figure is exemplary. In embodiments not shown in the figures, the bridges and / or openings are arranged differently, wherein in particular an irregular arrangement can be provided. The same applies to the opening widths shown for the openings 4. These are also purely exemplary.

[0036] At present, the flexible network structure 2 has a rectangular, in particular square shape, with outer edges 5, 6, 7, 8 arranged opposite each other in pairs. The shape shown is exemplary. In embodiments not shown in the figures, the flexible network structure is circular, oval or otherwise adapted to the geometry of the bone flap to be fixed.

[0037] As especially in Figure 3 As shown in the figure, the flexible network structure 2 is thinner than the bone structure C, D involved. Currently, the flexible network structure 2 has a thickness t of 0.4 mm. In an embodiment not shown in the figure, the thickness of the flexible network structure varies between 0.2 mm and 0.5 mm. Due to the small thickness and the fact that it is made of plastic material K, the flexible network structure 2 can be easily cut and its dimensions can be matched to the bone flap D to be fixed. In addition, due to its properties, the network structure 2 can easily be matched in its shape to the protuberances or other geometries of the bone structure C, D involved.

[0038] In the embodiment shown, the flexible network structure 2 is a fabric G, in which the bridges 3 are arranged crosswise without knots. In this respect, a nodeless network can also be referred to. In an embodiment not shown in the figure, the bridges are firmly connected to each other at their respective intersections, which can also be referred to as a knotted network.

[0039] In an embodiment not shown in the figures, the flexible network structure 2 is not designed in the form of a woven fabric, but instead is designed as a knitted fabric, a knitted fabric, a nonwoven fabric or the like.

[0040] As especially Figure 2As shown in FIG, the flexible network structure 2 has a translucent property. Therefore, the bone flap D, the annular gap S and the region of the bony skull C arranged below the flexible surface structure 2 can be seen through the flexible surface structure 2. This allows, in particular, precise positioning and is accompanied by other advantages that are also described in more detail.

[0041] exist Figures 2 to 5 In the embodiment shown in , a material-fitting fastening of the flexible network structure 2 to the bone structures C, D is provided. For this purpose, the implant 1 has an adhesive A. The adhesive A is applied to the flexible surface structure 2 in the form of an adhesive layer 9 and is additionally introduced into the opening 4 in the form of an adhesive filler 10 (see Figure 5 ). In an embodiment not shown in the figure, the adhesive A is provided in the form of an adhesive layer or an adhesive filler. In the present case, the adhesive A is a medical textile adhesive H that hardens under the influence of UV radiation. Due to the translucent properties of the flexible network structure 2, the textile adhesive H can be hardened particularly easily, since the UV radiation required for this purpose can be radiated through the flexible network structure 2.

[0042] In the embodiment shown, the implant 1 also has a medical active ingredient W. In the present case, the medical active ingredient W is applied to the flexible network structure 2 in the form of an active ingredient layer 13 and is additionally introduced into the opening 4 in the form of an active ingredient filling 14. The shown equipment of the implant 1 with the medical active ingredient W is optional and therefore not present in all embodiments. It is also possible that the active ingredient layer 13 and the adhesive layer 9 are combined into one layer, so to speak. In other words, the active ingredient W can be a component of the adhesive layer 9 or vice versa. In this context, Figure 5 The arrangement of the layers 13 , 9 shown in FIG. 1 can also be regarded as schematically highly simplified.

[0043] Furthermore, the implant 1 currently has a first protective layer 11 and a second protective layer 12. The first protective layer 11 is applied at least indirectly to the lower side 21 of the flexible network structure 2. The second protective layer 12 is applied at least indirectly to the upper side 22 of the flexible network structure 2. Indirectly means that the respective protective layer 11, 12 can be applied to other layers depending on the layer structure and thus indirectly to the respective side of the flexible network structure 2. Currently, the second protective layer 12 is applied directly to the upper side 22. Currently, the first protective layer 11 is applied directly to the adhesive layer 9 and is therefore applied indirectly to the lower side 21.

[0044] Both protective layers 11, 12 are removable and are removed before applying the implant 1. In the present case, the protective layers 11, 12 are films made of a plastic material suitable for this purpose. In the embodiment shown, the plastic material is PTFE.

[0045] Figure 5It is schematically shown that the plastic material K is currently provided with non-metallic additives Z1, Z2. The additives Z1, Z2 are currently a mixture of glass fibers Z1 and ceramic particles Z2. Providing the plastic material K with the additives is optional and serves to improve the mechanical properties and / or osteointegration of the flexible network structure 2.

[0046] Currently, the plastic material K is a composite material consisting of polypropylene P1 and polyglycolic acid P2.

[0047] In order to fix the bone flap D with the aid of the implant 1, the first protective layer 11 is first removed. The flexible network structure 2 is then pressed with the adhesive layer 9 at the front onto the outer side DA of the bone flap D. Alternatively, the implant 1 is placed on a flat base with the second protective layer at the front. The bone flap D is then pressed with the outer side DA onto the underside 21 of the flexible network structure 2, more precisely onto the adhesive layer 9 arranged there. The assembly of the implant 1 and the bone flap D (without the first protective layer 11) is then repositioned in the area of ​​the cranial opening B. After the repositioning, the area of ​​the flexible network structure 2 that protrudes laterally beyond the bone flap D and the annular gap S is pressed onto the outer side CA of the surrounding bony skull C.

[0048] The textile adhesive G is then cured, wherein the second protective layer 12 can be removed before or after curing.

[0049] exist Figures 2 to 5 In the embodiment shown in , the adhesive A is a component of the implant 1. Alternatively, the adhesive A can be provided as a separate product.

[0050] Figure 6 A kit 100 is shown with a flexible network structure 2 and an adhesive A, wherein the adhesive is provided as a separate product 40. The separate product 40 may be, for example, a container in the form of a tube or the like filled with the adhesive A. The adhesive A is applied to the flexible network structure 2 before the flexible network structure 2 is applied.

[0051] Figure 7 Another kit 200 is shown having a flexible network structure 2 and a plurality of fastening elements 50. The fastening elements 50 are configured to fasten the flexible surface structure 2 to the bone structures C, D (see Figure 8 ). At present, the fastening element 50 is a pin, which is respectively inserted into the outer side DA of the bone flap D or into the outer side CA of the surrounding bony skull C. In the inserted state, the fastening element 50 forms, so to speak, an anchoring point at which the flexible network structure 2 can be anchored.

[0052] With regard to further features of the flexible network structure 2 comprised in the kit 100 , 200 , reference is made and explicit reference is made to what has been said previously.

Claims

1. An implant (1) for fixing a skull flap (D) in a cranial opening (B) of a bony skull (C), comprising a flexible network structure (2) with bridge portions (3) and openings (4) constructed between the bridge portions, wherein the flexible network structure (2) is made of a plastic material (K) and is configured to be fastened at the skull flap (D) and the bony skull (C).

2. The implant (1) according to claim 1, It is characterized in that The flexible network structure (2) is translucent.

3. Implant (1) according to claim 1 or 2, It is characterized in that The flexible network structure (2) has a thickness (t) of 0.2 mm to 0.5 mm.

4. Implant (1) according to any one of the preceding claims, It is characterized in that The flexible network structure (2) is isotropically elastic.

5. Implant (1) according to any one of the preceding claims, It is characterized in that The bridges (3) are arranged crosswise without knots, and the flexible network structure (2) is constructed in the form of a knitted fabric or a woven fabric (G).

6. Implant (1) according to any one of the preceding claims, It is characterized in that The plastic material (K) comprises polypropylene (P1) and / or polyglycolic acid (P2).

7. Implant (1) according to any one of the preceding claims, It is characterized in that The plastic material (K) contains non-metallic additives (Z1, Z2), preferably glass fibers (Z1) and / or ceramic particles (Z2).

8. Implant (1) according to any one of the preceding claims, Features At least one medically active ingredient (W), which is applied to the flexible network structure (2) in the form of an active ingredient coating (13) and / or introduced into the opening (4) in the form of an active ingredient filling (14).

9. Implant (1) according to any one of the preceding claims, Features Adhesive (A), which is applied to the flexible network structure (2) in the form of an adhesive layer (9) and / or introduced into the opening (4) in the form of an adhesive filling (10).

10. Implant (1) according to claim 9, It is characterized in that The adhesive (A) is a medical textile adhesive (H) which hardens under the influence of UV radiation.

11. Implant (1) according to any one of the preceding claims, Features At least one removable first protective layer (11), which is at least indirectly applied to the lower side (21) of the flexible network structure (2), and / or is characterized by a removable second protective layer (12), which is at least indirectly applied to the upper side (22) of the flexible network structure (2).

12. A kit (100) having an implant (1) according to any one of claims 1 to 8 and having an adhesive (A) configured to bond the flexible network structure (2) to the bone flap (D) and the bony skull (C).

13. A kit (200) comprising an implant (1) according to any one of claims 1 to 8 and a plurality of fastening elements (50), which are configured to fasten the flexible network structure (2) to the bone flap (D) and the bony skull (C) in a force-fitting and / or form-fitting manner.

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