Skull fixation device for decompression / extended craniectomy

Abstract

The invention describes a skull fixation device for decompressive / extended craniectomy, comprising a cover plate and a plurality of brackets (3A, 3B, 3C, 3D, 3E, 3F). The device is designed to treat pathological conditions that cause brain herniation and consequent increase in intracranial pressure, of the type that form openings on the skull by milling along the edges of the craniotomy, to allow the brain to expand, and to apply the cover plate at a certain vertical distance from the edges of the craniotomy, with the function of protecting and containing the brain. The cover plate is connected to the edges of the craniotomy by means of a plurality of brackets (3A, 3B, 3C, 3D, 3E, 3F), which are simultaneously fixed to the cover plate and to the edges of the craniotomy.

Description

[0001] This invention relates to a cranioplasty device for decompression / expanded craniectomy.

[0002] The skull is a rigid and non-expandable shell. However, due to conditions such as brain tumors, infections, hemorrhages, and hydrocephalus, the increased volume of its contents can lead to elevated intracranial pressure. Intracranial pressure exceeding a certain limit is a harmful and potentially fatal condition, capable of triggering a cascade of events leading to cerebral ischemia and necrosis.

[0003] Treatment of intracranial hypertension involves the use of certain medications, sedation and ventilation techniques, and the removal of cerebrospinal fluid (CSF) or space-occupying lesions (tumors, hematomas). However, in many cases, this is insufficient to restore intracranial pressure to an acceptable level, necessitating decompressive craniectomy. This technique involves removing a large portion of the skull and opening the dura mater, allowing the swollen brain to herniate outward through the surgical defect in the skull. Decompressive craniectomy improves clinical outcomes through various mechanisms: it reduces intracranial pressure, improves cerebral perfusion, and reduces the risk of brain herniation and subsequent compression of important structures such as the brainstem. Patients who survive the acute phase of intracranial hypertension will subsequently undergo cranioplasty, which includes repositioning the previously removed bone flap or placing a skull prosthesis made of synthetic materials. The interval between decompressive craniectomy and subsequent cranioplasty can be several weeks or months, during which time the brain is at risk of traumatic injury, thus requiring patients to wear protective measures such as helmets or protective caps. Other complications associated with bone flap loss include "burr hole syndrome," caused by the direct transmission of atmospheric pressure effects to the brain tissue, and complications related to adhesions that form between the subcutaneous soft tissue, dura mater, and brain, which may lead to bleeding and increase the operation time and risk in the bone flap repositioning procedure.

[0004] To reduce the risks associated with bone flap loss and cranioplasty, alternatives to classic decompressive craniectomy have been devised. These alternative techniques share the common feature that the bone flap remains in place after being cut and separated from the remaining skull.

[0005] When the bone flap is fixed to only one side so that it can hinge and open like a door under the pressure of cerebral edema, these techniques are called "hinged craniectomy" (see, for example, Kathryn Ko's patent US8439956B2); when the bone flap floats freely on the herniated brain tissue, it is called "floating craniectomy".

[0006] These techniques require preventative measures to avoid cerebral edema and subsequent bone flap subsidence after the centrifugal thrust ceases.

[0007] There are also telescopic fixation systems that allow the bone flap to be lifted and subsequently repositioned to its original location after the outward thrust of the brain tissue has stopped (this type has several patents held by Khanna, such as US9603626B2).

[0008] In the aforementioned systems (articular, telescopic, or floating), the increase in intracranial volume resulting from the herniation of brain tissue through the craniotomy is facilitated by the brain's pushing force against the bone flap itself. Therefore, the brain must overcome the resistance of the skin and muscle flaps—a considerable resistance. In articulated craniectomy, the pushing force must overcome the resistance of the skin and muscle flaps on the bone flap, which can only be separated on one side. In all cases, the volume that could have been used for brain expansion is occupied by the volume of the bone flap itself, potentially reducing the effectiveness of the intervention.

[0009] The inventors of this application filed Italian patent application number 102022000003821 on February 3, 2022, using an innovative device to solve the above-mentioned problem.

[0010] However, the device still needs improvement because it tends to bend at the end of the surgical implantation and cannot provide an effective gap between the two parts of the skull.

[0011] The object of this invention is to overcome the aforementioned drawbacks by using a method that allows the bone flap to remain in situ, but is neither like the classic decompression craniectomy technique nor like any other known system. This concept can be defined as extended craniectomy, i.e., expanding the skull in a stable manner. The improved device of this invention provides various operating configurations that allow for more immediate and simpler use, some of which are equipped with folding inserts to facilitate the surgeon's manipulation during craniectomy.

[0012] As described below, the above and other objectives are achieved by using a cranioplasty device for decompression / expanded craniectomy according to claim 1, which allows the brain to herniate freely while providing effective protection for the brain itself.

[0013] This device is suitable for treating pathological conditions that lead to brain herniation and consequently increased intracranial pressure, and belongs to the type that provides the following functions: - An opening is created by milling along the cut edge of the skull to allow the brain to expand; and - Apply a covering that protects and accommodates the brain's functions; The cover plate is connected to the cranial incision edge via multiple brackets, which are simultaneously fixed to the cover plate and the cranial incision edge, and constitute the device of the present invention.

[0014] The length of these braces determines the amount of increased volume available for the herniated brain.

[0015] According to a preferred embodiment, the cover plate may be made from a biocompatible synthetic material or the same bone flap removed during craniectomy. In this case, the bone must be milled according to the cutting guide to ensure alignment between the opening and the synthetic cover plate.

[0016] Therefore, the cover plate is held elevated by brackets to overcome the resistance of the muscle-skin flap. These brackets are strong enough to ensure a seal even in the event of head trauma, and flexible enough to be bent with special forceps to accommodate the synthetic cover plate or the bone flap to be lifted during implantation.

[0017] This system is based on observations of a large number of patients who underwent classic decompression craniectomy. Analysis of imaging data made it possible to quantify the degree of herniation, which provided a basis for determining the volume of brain space that the device of this invention must leave to allow for free herniation.

[0018] Since cerebral edema and intracranial hypertension are dynamic processes, the maximum degree of expansion can be assessed and quantified, thereby allowing for the design of the bracket height accordingly.

[0019] The device according to the invention comprises the aforementioned bracket, providing the brain with the space required for its herniation, thus allowing the brain to expand freely within this space.

[0020] According to a preferred embodiment, the bracket is made of titanium and has a central body (which functions as a spacer) and two flanges that stabilize it at anchor points on the skull and prevent bone flaps from sinking.

[0021] Preferred embodiments and non-obvious variations of the invention constitute the subject matter of the dependent claims.

[0022] It should be understood that all appended claims form an integral part of this specification.

[0023] The present invention overcomes the aforementioned disadvantages because the brain herniates completely freely without having to overcome any resistance to the movement of the bone flap, since the bone flap has been positioned in a way that provides the brain with all the space it needs.

[0024] It is obvious that numerous variations and modifications can be made to the content (e.g., involving shape, size, arrangement, and parts with equivalent functions) without departing from the scope of the invention, as shown in the appended claims.

[0025] The present invention will be better described by way of some preferred embodiments, which are provided by way of example rather than limitation, and with reference to the accompanying drawings, wherein: - Figures 1 to 4 A first embodiment of the device of the present invention is shown; - Figures 5 to 8 A first embodiment of the device of the present invention equipped with a curved lug is shown; - Figures 9 to 12 A second embodiment of the device of the present invention is shown; - Figures 13 to 16 A second embodiment of the device of the present invention equipped with a curved lug is shown; - Figures 17 to 20 A third embodiment of the device of the present invention is shown; and - Figures 21 to 24 A third embodiment of the device of the present invention equipped with a curved lug is shown.

[0026] Therefore, the present invention relates to a cranioplasty fixation device for decompression / expanded craniectomy, comprising a cover plate (4) and a plurality of brackets (3A, 3B, 3C, 3D, 3E, 3F), the device being designed to treat pathological conditions leading to brain herniation and consequently increased intracranial pressure, belonging to the type of milling an opening along the cranioplasty incision edge on the skull to allow brain expansion, and the cover plate being applied at a certain vertical distance to the cranioplasty incision edge, having the function of protecting and accommodating the brain, the cover plate being connected to the cranioplasty incision edge by the plurality of brackets (3A, 3B, 3C, 3D, 3E, 3F), these brackets being simultaneously fixed to the cover plate (4) and the cranioplasty incision edge.

[0027] Referring to the accompanying drawings, three different embodiments of the innovative brackets (3A, 3B, 3C, 3D, 3E, 3F) of the present invention are shown (each may or may not be equipped with curved lugs). These brackets (3A, 3B, 3C, 3D, 3E, 3F) are secured to this edge by screws (not shown), and cover plates (not shown) are secured to these brackets (3A, 3B, 3C, 3D, 3E, 3F).

[0028] According to a preferred embodiment, these brackets (3A, 3B, 3C, 3D, 3E, 3F) are made of titanium and include: - A central planar body (10); - The first flange (31) and the second flange (32) are planar and located on mutually perpendicular planes, and function as a spacer between the cranial incision edge and the cover plate. The first flange (31) is connected to the central body (10) and is coplanar, and the second flange (32) is connected to the central body (10) and is perpendicular. - The third flange (33) and the fourth flange (35) are respectively equipped with a first opening (34) and a second opening (36) for passing through the connecting screw. The third flange (33) is connected to the central body (10) and is perpendicular to it. The fourth flange (35) is connected to the central body (10) and is coplanar. The third flange (33) is arranged on the opposite side of the central body (10) relative to the first flange (32). The third and fourth flanges (33, 35) fix the bracket (3A, 3B, 3C, 3D, 3E, 3F) to the anchor point on the skull and prevent the cover plate from sinking.

[0029] In some configurations, the central body (10) may also be equipped with an opening (11) to reduce weight.

[0030] The illustrated embodiment includes brackets (3A, 3B, 3C, 3D, 3E, 3F), each equipped with two third flanges (33) and two fourth flanges (35), but it is obviously also possible to configure them with only one third flange (33) and only one fourth flange (35), which can be achieved by extending along the centerline. Figures 1 to 24 The bracket shown is clearly obtained by dividing it in half.

[0031] In the embodiments of the brackets (3B, 3D, 3F) (respectively in...) Figures 5 to 8 , Figures 13 to 16 and Figures 21 to 24 As shown in the figure, the brackets (3B, 3D, 3F) are equipped with a first curved guide line (20) located at the connection between the central body (10) and the second flange (32), and a second curved guide line (21) located at the connection between the central body (10) and the first flange (31). These first and second curved guide lines (20, 21) facilitate slight bending of the surface (10) of the central body during the insertion step of the brackets (3B, 3D, 3F) and its operation, simplifying installation and improving the operation of the device of the present invention.

[0032] Generally, the first flange (31) of the central body (10) rests on the cranial incision edge, while the second flange (32) is designed to accommodate the cover plate. The opening distance between the cranial incision edge and the cover plate is defined by the length (L) of the central body (10).

[0033] The brackets (3A, 3B, 3C, 3D, 3E, 3F) are strong enough to ensure a seal even in the event of head trauma, and are flexible enough to be held and bent with special pliers (not shown) to accommodate the implantation of the cover plate.

[0034] According to another preferred embodiment, the brackets (3A, 3B, 3C, 3D, 3E, 3F) are made of a thermoplastic material (e.g., polyetheretherketone, PEEK) or a composite material with a thermoplastic matrix (e.g., carbon fiber impregnated with PEEK or other thermoplastic polymers). In this case, it may be necessary to heat the brackets (3A, 3B, 3C, 3D, 3E, 3F) sufficiently to form them.

[0035] It is clear from the above description that the fundamental technical problem has been completely solved, because the device according to the invention defines a space for the free herniation of the brain.

Claims

1. A craniostomy fixation device for decompression / expanded craniectomy, comprising a cover plate (4) and a plurality of brackets (3A, 3B, 3C, 3D, 3E, 3F), said device being designed to treat a pathological condition leading to brain herniation and consequently increased intracranial pressure, belonging to the type involving milling an opening along the craniostomy incision edge on the skull to allow brain expansion, and the cover plate being applied at a certain vertical distance to the craniostomy incision edge, having the function of protecting and accommodating the brain, said cover plate being connected to the craniostomy incision edge by said plurality of brackets (3A, 3B, 3C, 3D, 3E, 3F), these brackets being fixed to both the cover plate and the craniostomy incision edge, said brackets (3A, 3B, 3C, 3D, 3E, 3F) comprising: - A flat central body (10), wherein the opening distance between the cranial incision edge and the cover plate is defined by the length (L) of the central body (10); - The first flange (31) and the second flange (32) are planar and located on mutually perpendicular planes, and function as a spacer between the cranial incision edge and the cover plate. The first flange (31) is connected to the central body (10) and is coplanar, and the second flange (32) is connected to the central body (10) and is perpendicular to it. - At least one third flange (33) and at least one fourth flange (35), each equipped with a first opening (34) and a second opening (36) for passing a connecting screw, the third flange (33) being connected to and perpendicular to the central body (10), and the fourth flange (35) being connected to and coplanar with the central body (10), the third flange (33) being arranged on the central body (10) on the opposite side of the first flange (32), the third flange (33) and the fourth flange (35) securing the brackets (3A, 3B, 3C, 3D, 3E, 3F) to anchor points on the skull and preventing the cover plate from sinking. The feature is that each of the brackets (3A, 3B, 3C, 3D, 3E, 3F) is equipped with two of the third flanges (33) and two of the fourth flanges (35).

2. The apparatus according to claim 1, characterized in that, The central body (10) is equipped with an opening (11) to reduce weight.

3. The apparatus according to any one of the preceding claims, characterized in that, The brackets (3B, 3D, 3F) are equipped with a first curved guide line (20) located at the connection between the central body (10) and the second flange (32), and a second curved guide line (21) located at the connection between the central body (10) and the first flange (31). The first curved guide line (20) and the second curved guide line (21) facilitate slight bending of the plane of the central body (10) during the insertion phase of the brackets (3B, 3D, 3F) and during its operation.

4. The apparatus according to any one of the preceding claims, characterized in that, The brackets (3A, 3B, 3C, 3D, 3E, 3F) are made of titanium.

5. The apparatus according to any one of claims 1 to 3, characterized in that, The brackets (3A, 3B, 3C, 3D, 3E, 3F) are made of thermoplastic material.

6. The apparatus according to claim 5, characterized in that, The thermoplastic material is polyetheretherketone (PEEK), or a composite material containing carbon fibers impregnated with PEEK.

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