WO2011107859A1

WO2011107859A1 - Femoral prosthesis for the articulation of the hip

Info

Publication number: WO2011107859A1
Application number: PCT/IB2011/000439
Authority: WO
Inventors: Gian Guido Riva; Enrico Sandrini
Original assignee: Samo Spa
Priority date: 2010-03-04
Filing date: 2011-03-03
Publication date: 2011-09-09
Also published as: ITUD20100041A1

Abstract

A femoral prosthesis (25, 125) for the articulation of the hip comprising a femoral head (10) made, at least on the surface, of a ceramic-based material, and having an internal cavity (14) formed by at least a first seating (18) and a second seating (20) disposed along a longitudinal or cephalic axis (Y). The first seating (18) has a transverse width (D1) greater than the transverse width (D2) of the second seating (20). The femoral prosthesis further comprises at least a first pin (15, 215, 315, 415, 515) and a second pin (115) each having a coupling portion to the femoral head. The coupling portion of the first pin is made in a single piece with said first pin and is shaped in a mating manner with the second seating. The coupling portion of the second pin is formed by two separate parts wherein the second part is an adaptor element (28, 128) shaped in a manner mating with the first seating.

Description

"FEMORAL PROSTHESIS FOR THE ARTICULATION OF THE HIP"

FIELD OF THE INVENTION

The present invention concerns a femoral prosthesis for the articulation of the hip.

BACKGROUND OF THE INVENTION

A femoral prosthesis is known, for the articulation of a femur in a hip, which comprises a pin, straight or curved, that is inserted and attached in the femoral neck, and a femoral head which is inserted in a mating acetabular cup located in an acetabular seating.

Normally, for reasons of structural resistance, it is preferred to have the articular coupling made completely of metal material, normally a cobalt based alloy, determining a coupling through metal-metal sliding.

Usually, if the prosthesis used only replaces part of the femoral head, leaving the femoral neck intact, it is called a covering prosthesis. Generally, in order to use covering prostheses it is necessary to have a good quality of the bone tissue and a minimum alteration of the anatomy of the femoral head.

Where these conditions are not met, it is necessary to adopt the known solution of the complete prosthesis.

One disadvantage of known solutions is that, for each type of prosthesis, complete or covering, a specific set of prosthetic components must be provided, which is made available to the orthopedic surgeon who, first of all, for example based on X-rays, decides which type of intervention to carry out, for example whether to implant a conventional prosthesis with an intra-medullar shaft or a covering prosthesis. However, it may happen that, in the course of the operation, the surgeon realizes that the solution of the prosthesis first chosen is not the best one, for example because the bone tissue in fact is in better condition than expected, or vice versa. In this case, having a specific set of prosthetic elements available may be a limitation for the effectiveness of the surgeon, increasing the overall times of the intervention.

Furthermore, the known solutions are not satisfactory when there is a disproportion between the femoral neck and the acetabular seating, because the sets of prosthetic components are normally correlated with regard to size and therefore cannot contemplate cases where there are big differences in size between the parts of the hip that have to be made to articulate.

Moreover, after prosthesis interventions, it is often necessary, normally after a year, to carry out a revision. In such cases, the surgeon may find difficulty in matching the materials present in the prosthetic implant with the possible new needs of the patient. For example, in the case of an original covering prosthesis, it could be necessary to convert the implant to a complete prosthesis. This need could clash with possible difficulties regarding the compatibility of the materials present, for example for the acetabular cup or the hemi-spherical femoral head, and those of the new implant. In other cases, there could also be an obvious waste of material, since it may be necessary to completely eliminate a prosthetic implant, where only a part of it needs revision.

The European patent application EP-A-1.407.728 describes a femoral prosthesis comprising a femoral head having an internal cavity that has two seatings with different diameters, of which one seating with a larger diameter is provided for a direct coupling with the femoral bone, suitably prepared.

The US patent US-A-6, 136,036 describes a prosthesis for the hip that comprises a shaft and a femoral head coupled by an adaptor which allows the position of the femoral head to be adjusted axially.

The US patent US-A-2,682,265 describes a support for an artificial femoral head.

One purpose of the present invention is to achieve a femoral prosthesis that can perform several prosthetic functions with minimum variations, so that it can be adapted quickly and easily, even in the course of the operation, to the real needs of the intervention to fit a hip prosthesis.

Another purpose of the present invention is to reduce the complexity of the intervention in cases of revision, and to allow a reduction in costs of this type of intervention.

Another purpose is to obtain a femoral prosthesis by means of which it is possible to selectively combine various types of pin to the same prosthetic head, so as to optimize on each occasion the configuration of the prosthetic implant to the real conditions of the articulation, according to whether it is necessary to implant a covering prosthesis or a complete one. Another purpose of the present invention is to achieve a femoral prosthesis with a head that can be easily replaced without intervening on the pin attached to the end of the femur.

Another purpose is to facilitate the work of the surgeon, allowing him to have a precise reference during the installation of the head, and also to implant the prosthesis in two distinct steps.

The Applicant has devised, tested and embodied the present invention to overcome the shortcomings of the state of the art and to obtain these and other purposes and advantages.

SUMMARY OF THE INVENTION

The present invention is set forth and characterized in the independent claim, while the dependent claims describe other characteristics of the invention or variants to the main inventive idea.

One feature of the present invention concerns a femoral prosthesis for the articulation of the hip comprising a femoral head, hemi-spherical in shape, provided to cooperate with a mating artificial acetabular cup inserted in the natural acetabular seating of the hip in said femoral prosthesis.

The femoral head according to the present invention has an internal cavity which is formed by at least a first seating and by a second seating disposed along a longitudinal axis, typically the cephalic axis, along which a connecting and clamping pin is inserted into the femur.

The first seating has a transverse width greater than the transverse width of the second seating.

Thanks to the different transverse width, the first and second seating can house different types of attachment pins to the femur, according to needs.

By transverse width we mean the size substantially orthogonal to the cephalic axis of the femoral head.

In some forms of embodiment, access into the internal cavity is through a first opening that defines a relative entrance plane.

In some forms of embodiment, the first and second seating are made intercommunicating, with progressively decreasing sizes, one after the other along the longitudinal insertion axis transverse to the entrance plane of the first opening, which in normal use is the cephalic axis of the femoral prosthesis in question.

In some forms of embodiment, the first seating is in a more external position with respect to the second seating along the longitudinal or cephalic axis, and is open on one side toward the outside of the femoral head, through the first opening, and on the other side, through a second opening, toward the second seating.

In some forms of embodiment, the second seating has a closed bottom.

In some forms of embodiment, the first seating and/or the second seating of the head have a truncated cone shape, allowing an efficient conical coupling with the selected pin, particularly in the case of a ceramic-metal coupling.

In some forms of embodiment, the femoral head according to the present invention is made, at least on the surface, of ceramic material. By ceramic material we mean a substantially pure ceramic material, or a mixture or composition mainly containing ceramic material, or again a ceramic covering of a metal surface.

Using ceramic material is advantageous not only because it is an anti-wear material, but also because, within the field of making and associating the various components of the prosthesis, it allows an effective coupling with a wide range of materials, both metals such as cobalt alloys, for example CoCrMo, titanium or alloys of titanium or others, and also polymers such as polyethylene, polyether ether ketone (PEEK), polycarbonate urethane (PCU), and also ceramics: it is thus possible to choose the most suitable coupling of materials, according to the real requirements and conditions of the articulation.

The femoral prosthesis for the articulation of the hip comprises not only the femoral head of the type described above, but also at least a first and a second connecting and clamping pin in a top portion of the femur.

According to the present invention, the femoral head is a distinct component, removable from said first and second pins.

Furthermore, according to the present invention, each first and second pin has a connection portion in the part of the femur affected by the prosthetic implant, and coupling portion with the femoral head, to determine therewith, directly or indirectly, a coupling by insertion into the internal cavity of the femoral head. By providing a suitable choice of the type and size of the coupling portion, the coupling is achieved selectively with the first seating or with the second seating, according to whether it is necessary to implant a covering prosthesis or a complete prosthesis.

In some forms of embodiment, where there is a direct coupling of the first pin and the femoral head, the coupling portion is made in a single piece with the first pin and is shaped, advantageously with a truncated cone shape, in a mating manner with the second seating so as to determine a stable constraint directly with the inside of the femoral head.

In this case, the prosthesis according to the present invention is advantageously used as a covering prosthesis. In fact, due to the coupling with the second seating, located more in depth, the part of the head, in particular a collar portion that develops around the more external first seating, covers the residual bone of the femoral head.

In other forms of embodiment, where there is an indirect coupling of the pin and femoral head, the coupling portion is formed by two separate parts.

In particular, a first part is a coupling end that extends from the connection portion of the second pin and a second part is an adaptor element suitable to be selectively coupled with the coupling end and shaped mating with the first seating so as to adapt the second pin to the sizes of the first seating and allow connection to the femoral head. Consequently, thanks to the adaptor element, the prosthesis according to the present invention can be easily configured also as a complete prosthesis, since coupling with the first, more external seating allows to configure the prosthetic implant dimensionally according to the part of the femur that is resected.

In some forms of embodiment, the adaptor element is advantageously shaped like a truncated cone, to ensure a secure and reliable constraint with the first seating of the femoral head.

In other forms of embodiment, the adaptor element has a coupling hole, advantageously truncated cone shaped, mating with the coupling end of the second pin, to achieve therewith a stable connection.

Thanks to the two seatings having different sizes and conformation, the femoral head and the relative prosthesis associated with it, are easily and quickly adaptable, even in the course of the operation, to the real needs of an intervention to fit a hip prosthesis.

Furthermore, thanks to the conformation described above, and the ceramic material chosen, the femoral head according to the present invention reduces the complexity of the intervention in the case of revisions and the costs of such types of intervention.

With the present invention it is possible to selectively combine various types of pin with the same femoral head so as to optimize, on each occasion, the configuration of the prosthetic implant according to the real conditions of the articulation.

Advantageously, the femoral prosthesis according to the present invention is of the at least partly interchangeable type, due to the fact that each first and second pin is a distinct element and does not form a single body with the femoral head.

Moreover, the prosthesis according to the present invention allows to perform the implant in two separate steps, inserting the first or the second pin in the femur at a first moment and, after making a relative seating on the natural femoral head, applying the head at a second moment.

Another advantage of the invention is that the first or the second pin can be made of a material, for example titanium or titanium alloy or cobalt alloy, particularly suitable for integration in a bone tissue, while the femoral head is made of ceramic material with the appropriate and high resistance to wear.

BRIEF DESCRIPTION OF THE DRAWINGS

These and other characteristics of the present invention will become apparent from the following description of a preferential form of embodiment, given as a non-restrictive example with reference to the attached drawings wherein:

- fig. 1 is a section of a femoral head according to the present invention;

- fig. 2 is a section of a covering femoral prosthesis implanted on the femoral neck, which uses the femoral head according to the present invention;

- fig. 3 is a section of a complete femoral prosthesis implanted on the femoral neck, which uses the femoral head according to the present invention;

- fig. 4 is a section of a part of the prosthesis in fig. 3;

- fig. 5 is a section of a variant embodiment of the part in fig. 4;

- fig. 6 is a section of the femoral head in fig. 1 associated with the part in fig. 4; - fig. 7 is a section of the femoral head in fig. 1 associated with the part in fig. 5;

- fig. 8 is a section of the femoral head in fig. 1 associated with a first form of embodiment of the first pin in a femoral prosthesis according to the present invention;

- fig. 9 is a section of the femoral head in fig. 1 associated with a second form of embodiment of the first pin in a femoral prosthesis according to the present invention;

- fig. 10 is a section of the femoral head in fig. 1 associated with a third form of embodiment of the first pin in a femoral prosthesis according to the present invention;

- fig. 1 1 is a section of the femoral head in fig. 1 associated with a fourth form of embodiment of the first pin in a femoral prosthesis according to the present invention;

- fig. 12 is a section of the femoral head in fig. 1 associated with a fifth form of embodiment of the first pin in a femoral prosthesis according to the present invention;

- fig. 13 is a view of the first form of embodiment of the first pin in fig. 8;

- fig. 14is a view of the second form of embodiment of the first pin in fig. 9;

- fig. 15 is a view of the third form of embodiment of the first pin in fig. 10;

- fig. 16is a view of the fourth form of embodiment of the first pin in fig. 1 1 ;

- fig. 17 is a view of the fifth form of embodiment of the first pin in fig. 12.

To facilitate comprehension, the same reference numbers have been used, where possible, to identify common elements in the drawings that are substantially identical. It is understood that elements and characteristics of one form of embodiment can conveniently be incorporated into other forms of embodiment without further clarifications.

DETAILED DESCRIPTION OF A PREFERENTIAL FORM OF

EMBODIMENT

With reference to the attached drawings, a femoral head 10 for a covering femoral prosthesis 25 (fig. 2) or a complete femoral prosthesis 125 (fig. 3), according to the present invention, is hemi-spherical in shape and has an external surface 12 with a curved shape mating with that of a relative acetabular cup previously inserted in a natural acetabular seating, not shown in the drawings. In some forms of embodiment of the present invention, the femoral head 10 is made, at least on the surface, of a ceramic material. This not only represents an anti-wear property of the femoral head 10, but also has the advantage of allowing coupling with a wide range of materials, both metal and polymer.

The femoral head 10 has an internal cavity 14, accessed through a first insertion opening 16 which defines a relative entrance plane P.

Inside the cavity 14, a first pin 15, 215, 315, 415, 515 or a second pin 1 15 for attachment to the femur is coupled, along a determinate longitudinal insertion axis, normally the cervical-cephalic axis Y of the head 10.

The cervical-cephalic axis Y is typically transverse to the entrance plane P. In some advantageous forms of embodiment, the cephalic axis Y is orthogonal to the entrance plane P of the femoral head 10.

The femoral head 10 is geometrically axial-symmetrical with reference to the cephalic axis Y along which the attachment pin is inserted and coupled in the top portion of the femur 1 1.

In particular, the first pin 15, 215, 315, 415, 515 or the second pin 1 15 on one side is connected and attached, in a known manner, to the diaphysiary part 1 1 of the femur and, on the other side, is inserted through the first opening 16 and constrained to the femoral head 10.

Consequently, all in all the femoral head 10 on the one side is coupled and articulates in the acetabular cup, and on the other side is constrained to the diaphysiary part 1 1 of the femur by means of the first pin 15, 215, 315, 415, 515 or the second pin 1 15.

The internal cavity 14 of the femoral head 10 is formed by a first seating 18 and a second seating 20, made in succession one with respect to the other along the cephalic axis Y.

The first seating 18 and the second seating 20 have an axial-symmetrical geometry with respect to the cephalic axis Y.

The first seating 18 is in an external position along the cephalic axis Y with respect to the second seating 20, and is open toward the outside of the femoral head 10, through the first opening 16. A second seating 20 is in a more internal position, or in depth, along the cephalic axis Y.

The first seating 18 is of the through type, having the first opening 16 toward the outside and a second opening 22 communicating with the second seating 20 aligned along the cephalic axis Y.

Consequently, on one side the first seating 18 faces the outside of the head 10 through the first entrance opening 16, whereas on the other side it opens into the second seating 20 through the second opening 22.

In some forms of embodiment, the second seating 20 is of the blind type, sharing the second opening 22 with the first seating 18 and having an internal bottom 24, which advantageously reproduces the same curve as the external surface 12.

The first seating 18 has a transverse width Dl greater than the transverse width D2 of the second seating 20 (fig. 1), so as to be able to house different types of pin, as described hereafter. This also causes the formation of a step 23 in correspondence with the second opening 22.

In some forms of embodiment, both the first seating 18 and the second seating 20 have a circular cross section, either constant or progressively decreasing, like a truncated cone, along the cephalic axis Y.

In such forms of embodiment with a substantially circular transverse geometry, in which the transverse width corresponds to the diameter, the main diameter Dl of the first seating 18 is greater than the main diameter D2 of the second seating 20, as is seen in fig. 1.

In some forms of embodiment, both the first seating 18 and the second seating 20 have a truncated cone geometry, and therefore each has a progressive reduction in diameter from the outside to the inside of the femoral head 10, although this reduction in diameter is limited with respect to the coupling requirements with the attachment pin in the femur. This is advantageous to determine a conical coupling with the attachment pin to the femur.

Fig. 2 shows how the femoral head 10 is used to achieve a covering prosthesis 25. In this application, the femoral neck 13 is left substantially intact.

A first pin 15 is connected and attached to the femoral neck 13, making a suitable hole to create a femoral connection seating 27.

The femoral head 10, coupled with the first pin 15, covers the top of the femoral neck 13.

In particular, the first pin 15 is a single body comprising a connection portion 19 of the oblong type, to be attached in the femur, and in a position at the top, a coupling portion 17 which has a shape mating with that of the second seating 20.

In this way, the coupling portion 17 can be stably coupled with the second seating 20, determining the overall constraint of the femoral head 10 and the femoral neck 13.

Advantageously, in some forms of embodiment, the coupling portion 17 is shaped like a truncated cone, to be efficiently constrained to the second seating

20 in the embodiment where it too is shaped like a truncated cone.

Consequently, in this application, the second seating 20 is engaged by the coupling portion 17 while the first seating 18 is engaged by the top portion of the femoral neck 13. Preferably, as can be seen in fig. 2, the femoral head 10 not only covers the top of the femoral neck 13 but also surrounds a lateral surface portion thereof, in particular the part that is housed in the first seating 18, with an end collar portion 26 of the external surface 12, allowing to achieve covering prostheses.

In some solutions, the coupling portion 17 is disc-shaped, with progressively inclined lateral walls, to define a desired truncated cone conformation or shaping.

The connection portion 19 of the first pin 15, in some advantageous solutions, is also shaped like a truncated cone, for a stable constraint in the connection seating 27.

In some forms of embodiment, the coupling portion 17 has a bigger transverse side than the transverse size of the connection portion 19.

Generally, both the coupling portion 17 and the connection portion 19 of the pin 15 are axial-symmetrical, with respect to a common axis or with respect to distinct axes.

In a first form of embodiment of the first pin, shown in figs. 8 and 13 and indicated by the reference number 15, the coupling portion 17 has an axis of symmetry which, in normal use, coincides with the cephalic axis Y, and which in turn coincides with the axis of symmetry of the connection portion 19. Consequently, the base 19a of the connection portion 19 is concentric or aligned with the coupling portion 17.

In a second form of embodiment of the first pin, shown in figs. 9 and 14 and indicated by the reference number 215, the coupling portion, indicated for convenience by the reference number 217, has an axis of symmetry which, in normal use, coincides with the cephalic axis Y, and which is different, but in any case parallel, with respect to the axis of symmetry Y¹¹ of the connection portion indicated by the reference number 219. Consequently, the base 219a of the connection portion 219 is eccentric, that is, offset, with respect to the coupling portion 217.

In a third form of embodiment of the first pin, shown in figs. 10 and 15 and indicated by the reference number 315, the coupling portion, indicated for convenience by the reference number 317, has an axis of symmetry which, in normal use, coincides with the cephalic axis Y, and which is different and inclined with respect to the axis of symmetry Yⁿⁱ of the connection portion indicated by the reference number 319. In this third form of embodiment, however, the base 319a of the connection portion 319 is concentric with respect to the coupling portion 17, whereas the remaining part of the coupling portion extends in an inclined direction with respect to the coupling portion 317 along the axis Y¹¹¹.

In a fourth form of embodiment of the first pin, shown in figs. 1 1 and 16 and indicated by the reference number 415, the coupling portion, indicated for convenience by the reference number 417, has an axis of symmetry which, in normal use, coincides with the cephalic axis Y, and which is different and inclined with respect to the axis of symmetry Y^1V of the connection portion indicated by the reference number 419. In this fourth form of embodiment, moreover, the base 419a of the connection portion 419 is eccentric with respect to the coupling portion 417. In this fourth form of embodiment, moreover, the axis Y^IV of the connection portion 419 is inclined toward the outside of the pin 415, that is, it is inclined as it is distanced from the cephalic axis Y.

In a fifth form of embodiment of the first pin, shown in figs. 12 and 17 and indicated by the reference number 515, the coupling portion, indicated for convenience by the reference number 517, has an axis of symmetry which, in normal use, coincides with the cephalic axis Y, and which is different and inclined with respect to the axis of symmetry Y^v of the connection portion, indicated by the reference number 519. In this fifth form of embodiment, moreover, the base 519a of the connection portion 519 is eccentric with respect to the coupling portion 517. Moreover, in the fifth form of embodiment, the axis Y^v of the connection portion 519 is inclined toward the inside of the pin 515, that is, it is inclined toward the cephalic axis Y.

It is clear that, similarly to the coupling portion 17 in figs. 2, 8 and 13, the coupling portions 217, 317, 417 and 517 shown in the figs. 9-1 1 and 14-16 also have a shape mating with that of the second seating 20, to achieve a stable constraint therewith, advantageously a conical coupling.

Fig. 3 shows how the femoral head 10 is used to make a complete prosthesis 125. In this application, the femoral neck 13 is completely resected.

A second pin 1 15 is connected and attached in the femoral diaphy siary part 1 1 , making a suitable hole to create a connection seating 127, substantially along the diaphy siary axis Y¹ (fig. 3).

The second pin 1 15, in particular, comprises a coupling portion 1 17, associable to the femoral head 10, and a curved connection portion 1 19 for attachment to the femur, which develops, when connected, along the diaphysiary axis Y¹.

Advantageously, the coupling portion 1 17 has a truncated cone shape, which progressively tapers upward.

The coupling portion 1 17 has a transverse size substantially comparable to the transverse size of the connection portion 19.

Moreover, the transverse size of the coupling portion 1 17 is less than the transverse size of the first seating 18 of the femoral head 10.

According to the present invention, the coupling portion 1 17 is formed by two separate parts able to be selectively coupled to each other, of which a first part is a coupling end 1 17a of the second pin 1 15, which extends from the connection portion 1 19, and a second part is an adaptor element 28 (figs. 3, 4 and 6) or 128 (figs. 5 and 7) able to be selectively coupled to the coupling end 1 17a.

By means of the adaptor element 28, 128 it is possible to conform the coupling end 1 17 dimensionally to the geometry of the first seating 18 and therefore to couple the same pin 1 15 to the femoral head 10.

To this purpose, the adaptor element 28, 128 has a shape and size mating with that of the first seating 18. In this way it is possible to configure the complete prosthesis 125 dimensionally according to the sizes of the part of the femoral neck 13 which is resected.

In some advantageous forms of embodiment, the adaptor element 28, 128 is shaped like a truncated cone mating with the first seating 18.

The adaptor element 28, 128 has a hole 30, 130 into which the coupling end 1 17a of the second pin 115 is inserted and attached.

In some forms of embodiment, the hole 30, 130 has a truncated cone shape, for an advantageous conical coupling with the adaptor element 28, 128 of the coupling portion 1 17.

In the solution shown in figs. 3-7, the hole 30, 130 is made through. According to a variant, not shown in the drawings, the hole 30, 130 can be blind.

Consequently, in the embodiment of the prosthesis 125, the first seating 18 of the femoral head 10 is engaged by the adaptor element 28, 128 in turn constrained to the coupling end 1 17a of the pin 1 15, while the second seating 20 is not used. In particular, the collar portion 26 of the femoral head 10 also surrounds the external lateral surface of the adaptor element 28, 128.

In the form of embodiment shown in figs. 3, 4 and 6, the hole 30 of the adaptor element 28, 128 is coaxial with respect to the axis, indicated in fig. 3 by the letter Y, along which the coupling end 1 17a develops. Therefore, the axis of the hole 30, indicated by the letter Z in figs. 4 and 6, coincides with the axis Y of the coupling end 1 17a. Consequently, the adaptor element 28 and the coupling end 1 17a are aligned and, in the use of the prosthesis 125, are also coaxial with the femoral head 10, as can be seen from figs. 3 and 6.

In the form of embodiment shown in figs. 5 and 7, the hole 130 of the adaptor element 28, 128 is eccentric with respect to the axis Y around which the coupling end 1 17a develops.

In particular, the axis of the hole 130, indicated in figs. 5 and 7 by the letter Z¹, and the axis Y of the coupling end 1 17a, are parallel and offset by a desired value of eccentricity.

Consequently, the adaptor element 128 and the coupling end 1 17a are misaligned and, in the use of the prosthesis 125, the coupling end 1 17a is also eccentric with respect to the femoral head 10, as can be seen in figs. 3 and 6.

Another variant, not shown in the drawings, can provide that the axis of the hole of the second pin 1 15 is inclined with respect to the cephalic axis Y of the coupling end 1 17a.

Another variant, not shown in the drawings, can provide that the axis of the hole of the second pin 1 15 is inclined, toward the inside or toward the outside, and also misaligned or eccentric, with respect to the cephalic axis Y of the coupling end 1 17a.

Claims

1. Femoral prosthesis for the articulation of the hip, comprising a femoral head (10) made, at least on the surface, of a ceramic-based material, and having an internal cavity (14), which is formed by at least a first seating (18) and a second seating (20) disposed along a longitudinal or cephalic axis (Y), said first seating (18) having a transverse width (Dl) greater than the transverse width (D2) of the second seating (20), characterized in that it also comprises at least a first pin (15, 215, 315, 415, 515) and a second pin (1 15), each having a corresponding connection portion (19, 1 19) to connect and clamp in a top portion of the femur (1 1 ) and a corresponding coupling portion (17, 1 17, 217, 317, 417, 517) to the femoral head (10), to allow the selective coupling of the second pin (1 15) or the first pin (15, 215, 315, 415, 515) respectively with the first seating (18) or with the second seating (20) of the femoral head (10), according to whether it is necessary to implant a covering prosthesis (25), or a complete prosthesis (125), wherein the coupling portion (17, 217, 317, 417, 517) of the first pin (15, 215, 315, 415, 515) is made in a single piece with said first pin (15, 215, 315, 415, 515) and is shaped in a mating manner with the second seating (20) so as to determine a stable constraint directly with said femoral head (10), and the coupling portion (1 17) of the second pin (1 15) is formed by two separate parts (1 17a; 28, 128) of which a first part is a coupling end (1 17a) which extends from the connection portion (1 19) of the second pin (1 15) and a second part is an adaptor element (28, 128) suitable to be coupled to the coupling end (1 17a) and shaped in a manner mating with the first seating (18) so as to allow connection to said femoral head (10).

2. Femoral prosthesis as in claim 1, characterized in that said coupling portion (17, 217, 317, 417, 517) is a truncated cone shape.

3. Femoral prosthesis as in claim 1 or 2, characterized in that said adaptor element (28, 128) is a truncated cone shape.

4. Femoral prosthesis as in claim 1, 2 or 3, characterized in that said femoral head (10) has a first opening (16) for access to the internal cavity (14), which defines an entrance plane (P), said internal cavity (14) being configured for the insertion, along said longitudinal or cephalic axis (Y), of a pin (15, 1 15, 215, 315, 415, 515) to connect and clamp said femoral prosthesis (25, 125) in a part of the femur (1 1), said entrance plane (P) being transverse to the longitudinal or cephalic axis (Y) along which said pin (15, 1 15, 215, 315, 415, 515) is inserted.

5. Femoral prosthesis as in any claim hereinbefore, characterized in that the first seating (18) and the second seating (20) of said femoral head (10) are made intercommunicating in succession one following the other along said longitudinal or cephalic axis (Y), said first seating (18) being in a more external position with respect to said second seating (20) along said longitudinal or cephalic axis (Y) and being open on one side toward the outside, through said first opening (16), and on the other side, through a second opening (22), toward the second seating (20).

6. Femoral prosthesis as in any claim hereinbefore, characterized in that it has a step (23) at the interface between the first seating (18) and the second seating (20) of said femoral head (10).

7. Femoral prosthesis as in any claim hereinbefore, characterized in that the first seating (18) and/or the second seating (20) of said femoral head (10) are a truncated cone shape.

8. Femoral prosthesis as in any claim hereinbefore, characterized in that the first seating (18) of said femoral head (10) is delimited laterally by a collar portion (26).