Cranial prosthesis

Abstract

The present invention concerns an improved cranial prosthesis (1). According to the invention, such an improved cranial prosthesis (1) comprising a lamina (3), made of a biocompatible material, configured to replicate the course of the outer surface of the cranial bone to be restored, where said lamina (3) comprises a portion of removable lamina (5) suitable for allowing intracranial access (7).

Description

[0001] CRANIAL PROSTHESIS

[0002] FIELD OF THE INVENTION

[0003] The present invention concerns an improved cranial prosthesis, and in particular a titanium cranial prosthesis that is implanted in the patient during cranioplasty surgeries, which allows the passage of ventricular catheters without the need to make further holes in the cranial box and / or remove the prosthesis.

[0004] BACKGROUND

[0005] As is known, the eventualities that lead to cranioplasty surgery being recommended can be diverse. The main ones are post-traumatic craniectomy, for example following bone fragmentation that prevents the reconstruction of the skull vault, demolitive craniectomy, for example for surgical treatment of tumours, and malformative syndromes that can create bone gaps.

[0006] In addition, there may be the outcomes of previous surgeries that may have led to osteitis and bone resorption around the prosthesis.

[0007] In all cases where it is necessary to restore the skull bone, use is made of a prosthesis that must reproduce the shape of the natural bone as much as possible.

[0008] Among the causes of failure of cranioplasty surgeries are those related to the formation of tissue fluid in the space between the dura mater and the cranioplasty. This accumulation of fluid has a detrimental effect on the cerebral parenchyma and increases the risk of infections. The formation of extradural fluid (which accumulates between the dura mater and the cranial prosthesis) often leads to having to remove the implant, with inevitable damage to the patient.

[0009] A further drawback that affects the prostheses of known type and that negatively impacts on the methods of intervention is linked to the need to prevent the formation of a cavity between the dura mater and the prosthesis that may cause, or at least favour, the accumulation of extradural fluid, with the consequences described above. To avoid this risk, the surgeon sutures the prosthesis to the dura mater in several places in order to obtain the greatest possible adhesion of the prosthesis to the dura mater. For this purpose, the prostheses, made of titanium or other materials, are provided with a plurality of preformed anchoring holes.

[0010] In any case, there is often a need to use ventricular catheters, which have the function of draining blood or cerebrospinal fluid, in cases of intracranial haematomas or endocranial hypertension, respectively.

[0011] Currently commercially available prostheses do not allow the positioning of ventricular catheters. This entails the need to make further intracranial holes using a craniotome, resulting in the formation of an additional cranial gap, which, subsequently, must be covered with prosthetic devices suitable for the purpose.

[0012] The alternative to creating further intracranial holes is to remove the implanted prosthetic device. However, this practice involves several drawbacks, including:

[0013] - greater risks linked to the need to make a wide incision for the removal of the entire implant;

[0014] - longer duration of surgery;

[0015] - increased risk of infection;

[0016] - higher costs due to the need to apply a new prosthesis, since the same ones, being single-use, cannot be re-implanted after being removed.

[0017] SUMMARY OF THE INVENTION

[0018] In light of the above, the task of the present invention is to make an improved cranial prosthesis that overcomes the limits of the prior art allowing to integrate an intracranial access, available directly on the prosthesis itself.

[0019] Within the scope of this task, it is an object of the present invention to make an improved cranial prosthesis that allows the surgeon to easily position a ventricular catheter.

[0020] Another object of the present invention is to make an improved cranial prosthesis that does not need to be removed, even in the case of surgeries for the reduction of intracranial haematomas or endocranial hypertension.

[0021] A further object of the invention consists in making an improved cranial prosthesis that is capable of providing the broadest guarantees of reliability and safety when used.

[0022] The task disclosed above, and also the objects mentioned and others which are more apparent below, are achieved by an improved cranial prosthesis according to claim 1.

[0023] Other features are provided in the dependent claims.

[0024] LIST OF FIGURES

[0025] Further characteristics and advantages will become more apparent from the exemplary but non-limiting description of a preferred embodiment of the present invention, illustrated with the aid of the accompanying drawings in which: figure 1 is a perspective view of the exocranial surface of an improved cranial prosthesis, according to the invention, with a relative magnification; figure 2 is a perspective view of the endocranial surface of the cranial prosthesis of figure 1, according to the invention, with a relative magnification; figures 3 and 4 illustrate in sectional perspective views, a detail of the improved cranial prosthesis, according to the invention; figure 5 illustrates, in a perspective view, a further detail of the improved cranial prosthesis, according to the invention, associated with an intraventricular catheter; figure 5a shows a magnification of a portion of figure 5; figures 6, 7 and 8 show a sequence of steps relating to the use of the improved cranial prosthesis according to the invention.

[0026] DETAILED DESCRIPTION OF THE INVENTION

[0027] With particular reference to the figures, the improved cranial prosthesis, globally indicated with reference numeral 1, comprises a lamina 3 made of a biocompatible material, configured to replicate the course of the outer surface of the cranial bone to be restored.

[0028] According to the invention, the lamina 3 comprises a portion of removable lamina 5 suitable for allowing intracranial access 7.

[0029] Preferably, the lamina 3 comprises a through-hole 70 at least partially closed by the portion of removable lamina 5. The intracranial access 7 is thus defined by said through-hole 70, once the aforesaid portion of removable lamina 5 has been removed from the remaining part of the lamina 3.

[0030] The access for the shunt can be positioned at any point of the prosthesis, although the classic positioning provided by the standard surgical technique for ventricular catheters is preferred.

[0031] In essence, therefore, the lamina 3 presents a first use configuration in which it presents a substantially continuous and complete covering surface, and a second use configuration, once the portion of removable lamina 5 has been removed, in which it has an interrupted covering surface at the intracranial access 7.

[0032] The portion of removable lamina 5 is preferably just a portion of the lamina 3 itself, and in fact it preferably has the same transverse thickness.

[0033] Preferably the portion of removable lamina 5 is connected to the remaining part of the lamina 3 by means of a frangible bridge 9.

[0034] In this way the removal of the portion of removable lamina 5 can take place simply by breaking the frangible bridge 9 and removing the portion 5 itself.

[0035] As illustrated in the attached figures, in particular figures 3 and 4, the frangible bridge 9 consists of a thin connecting portion of lamina 90 connecting the portion of removable lamina 5 to the remaining part of the lamina 3.

[0036] This thin portion of connecting lamina 90 may present a transverse thickness substantially equal to that of the lamina 3 itself and a width preferably of less than 2.1 mm, more preferably less than 1.7 mm and even more preferably less than 1.3 mm.

[0037] Preferably, the through-hole 70, which once the portion of removable lamina 5 has been removed constitutes the intracranial access 7, comprises at least a first zone 71 presenting a substantially circular-shaped contour interrupted exclusively at the point 72 wherein the portion of removable lamina 5 is connected to the remaining part of the lamina 3.

[0038] Advantageously, as illustrated in particular in figures 5 and 5a, the intracranial access 7 is configured to allow the insertion of a ventricular catheter VC. Such a ventricular catheter VC may in particular be inserted through the first zone 71 of the through-hole 70. Note that ventricular catheters VC generally have a diameter greater than 2.5 mm and, in any case, always have a diameter greater than 1.8 mm.

[0039] Preferably, as illustrated in figure 5a, the interruption of the substantially circularshaped contour of the first zone 71 of the through-hole 70 presents a maximum width L of less than 2.5 mm, preferably less than 2.1 mm, and more preferably less than or equal to 1.8 mm.

[0040] In this way, as illustrated in figure 5a, it is possible to ensure that a ventricular catheter VC inserted inside the intracranial access 7 remains confined inside the first zone 71 of the through-hole 70 and does not for example come into contact with the residual part 91 of the frangible bridge 9 which, as explained below, remains attached to the lamina 3 even after the portion of removable lamina 5 has been removed. This residual part 91 of the frangible bridge 9 may in fact have sharp edges that might damage the ventricular catheter VC.

[0041] As illustrated in the attached figures, the through-hole 70 also comprises at least a second zone 73 crossed by the frangible bridge 9, i.e. crossed by the thin connecting portion of lamina 90 connecting the portion of removable lamina 5 to the remaining part of the lamina 3.

[0042] Advantageously, the frangible bridge 9 is configured to break upon pulling the portion of removable lamina 5 in a direction away from the remaining part of the lamina 3.

[0043] As illustrated in the sequence of figures from 6 to 8, in fact, the portion of removable lamina 5 can be grasped and lifted upwards, by the surgeon, with an appropriate instrument, until the frangible bridge 9 breaks.

[0044] Preferably, the second zone 73 of the through-hole 70 extends from either sides of the frangible bridge 9 forming a pair of apertures 74, 75 suitable for allowing the insertion of the tips of an instrument suitable for cutting said connecting bridge 9. Indeed, as an alternative to removing the portion of removable lamina 5 upon pulling, for example with a forceps or other similar instrument, the surgeon may decide to cut the frangible bridge 9, for example with a pliers or other similar instrument.

[0045] The apertures 74, 75 of the second zone 73 of the through-hole 70 are respectively separated from the first zone 71 of the through-hole 70 by two projections 31, 32 of the lamina 3, which face each other, so as to define, at point 72, the interruption of width L of the contour of the edge of the first zone 71 of the through-hole 70 described above.

[0046] Preferably, the improved cranial prosthesis 1 comprises, at the inner surface of the lamina 3, i.e. the surface facing the patient's meninges (endocranial surface), a abutment element 11 for the portion of removable lamina 5. Said abutment element 11 for the portion of removable lamina 5 is suitable for preventing the portion of removable lamina 5 from moving towards the patient's brain. In fact, the presence of this abutment element 11 makes it possible to avoid that, after implanting the prosthesis 1, the portion of removable lamina 5 may inadvertently penetrate inwards, in the direction of the patient's meninges, in particular when it is separated and removed from the remaining part of lamina 3.

[0047] The improved cranial prosthesis 1 is preferably made of titanium or a titanium alloy, and, even more preferably, it is made by means of additive manufacturing techniques by powder sintering, in particular with EBM (electron beam melting) techniques. Thanks to this particular production technology, it is in fact possible to model the prosthesis with extreme precision on the patient's anatomy, detected by CT (computerised axial tomography).

[0048] Advantageously, the lamina 3 is made based on the image acquired by CT or similar methodology of the patient's bone to be restored, suitably provided with the portion of removable lamina 5. Thanks to additive manufacturing techniques, it is in fact possible to exactly replicate the course of the surface of the bone to be restored by means of the prosthesis, obtaining very complex geometries, generally not obtainable by moulding, also including the portion of removable lamina 5 according to the invention.

[0049] Advantageously, the lamina 3 comprises a plurality of fixing holes 33 placed, for example, on sections 34 of the lamina 3 that project outwards.

[0050] Advantageously, as illustrated in the appended figures, the lamina 3 comprises a plurality of small through-holes 35 distributed on the surface of the lamina 3 itself, which contribute to the lightening of the prosthesis 1 and its radiolucency. These small through-holes 35 also allow to facilitate suturing operations in the event that the surgeon decides to perform such an intervention. The functioning of the improved cranial prosthesis is clear and evident from what has been described.

[0051] In particular, if following the implantation of the prosthesis 1 there should be a need for surgical intervention to reduce any intracranial hematomas or any endocranial hypertension, it will be sufficient to tear, as if it were a tab, the portion of removable lamina 5 from the remaining part of the lamina 3 so as to expose the through-hole 70 previously obtained in the lamina 3 itself and thus create an intracranial access 7 through which it will be possible to insert a ventricular catheter VC.

[0052] Furthermore, the improved cranial prosthesis is configured in such a way as to ensure that the possible ventricular catheter VC inserted inside the intracranial access 7 does not risk being damaged, for example, by sharp elements or edges that the removal of the portion of removable lamina 5 could leave in place.

[0053] As mentioned, the portion of removable lamina 5 is easily removable by the surgeon, either by traction, by pulling it outwards until the frangible bridge 9 breaks, or by directly cutting said bridge 9 with a cutting instrument.

[0054] In practice, it has been found that the improved cranial prosthesis, according to the present invention, fulfils the task as well as the intended purposes as it allows to make, directly on the prosthesis itself, an intracranial access through which the surgeon can easily position a ventricular catheter.

[0055] Another advantage of the improved cranial prosthesis, according to the invention, consists in the fact that surgeries for the reduction of intracranial hematomas or endocranial hypertension do not require the complete removal of the prosthesis, and the consequent reimplantation again of a new cranial prosthesis.

[0056] The improved cranial prosthesis thus conceived is susceptible to several modifications and variations, all falling within the scope of the inventive concept.

[0057] Furthermore, all the details can be replaced by other technically equivalent elements. In practice, any materials can be used according to requirements, as long as they are compatible with the specific use, the dimensions and the contingent shapes.

Claims

CLAIMS1. Improved cranial prosthesis (1) comprising a lamina (3), made of a biocompatible material, configured to replicate the course of the outer surface of the cranial bone to be restored, characterized by the fact that said lamina (3) comprises a portion of removable lamina (5) suitable for allowing intracranial access (7).

2. An improved cranial prosthesis (1) according to the preceding claim, wherein said lamina (3) comprises a through-hole (70) at least partially closed by said portion of removable lamina (5), said intracranial access (7) being defined by said through-hole (70) following removal of said portion of removable lamina (5) from said lamina (3).

3. An improved cranial prosthesis (1) according to one or more of the preceding claims, wherein said portion of removable lamina (5) is connected to said lamina (3) by means of a frangible bridge (9).

4. An improved cranial prosthesis (1), according to the preceding claim, wherein said frangible bridge (9) consists of a thin connecting portion of lamina (90) connecting said portion of removable lamina (5) to said lamina (3).

5. An improved cranial prosthesis (1) according to one or more of the preceding claims, wherein said lamina (3) comprises a through-hole (70) at least partially closed by said portion of removable lamina (5), said through-hole (70) comprising at least a first zone (71) presenting a contour of substantially circular shape interrupted exclusively at the point (72) wherein said portion of removable lamina (5) is connected to said lamina (3).

6. An improved cranial prosthesis (1), according to the preceding claim, wherein the interruption of said substantially circular-shaped contour presents a maximum width (L) of less than 2.5 mm, preferably less than 2. 1 mm and more preferably less than or equal to 1.8 mm.

7. An improved cranial prosthesis (1) according to one or more of the preceding claims, wherein said lamina (3) comprises a through-hole (70) at least partially closed by said removable portion of said lamina (5), said through-hole (70) comprising at least a second zone (73) crossed by said frangible bridge (9).

8. An improved cranial prosthesis (1) according to one or more of the preceding claims, comprising, at the inner surface of said lamina (3), a abutment element (11) for said portion of removable lamina (5).

9. An improved cranial prosthesis (1) according to one or more of the preceding claims, wherein said frangible bridge (9) is configured to break upon pulling said portion ofremovable lamina (5) in a direction away from said lamina (3).

10. An improved cranial prosthesis (1), according to the preceding claim, wherein said second zone (73) of said through-hole (70) extends from either side of the frangible bridge (9), forming a pair of apertures (74, 75) suitable for allowing the insertion of the tips of an instrument suitable for cutting said frangible bridge (9).