ES2975513T3 - Modular spacer device - Google Patents

Abstract

A modular spacer device implantable in the human body for the treatment of an infected joint seat, comprising a stem element, a head or ball element and coupling elements between the stem element and the head, wherein said coupling elements comprise a plurality of elongated teeth, placed at preset distances from each other, and a plurality of housings for the teeth themselves. (Automatic translation with Google Translate, without legal value)

Description

DESCRIPTION

Modular spacer device

TECHNICAL FIELD OF THE INVENTION

The present invention relates to a modular spacer device for the treatment of a joint seat of the human body affected by an infection, for example, the hip or shoulder seat.

The present invention also relates to a temporary and disposable type spacer device, usable for the two-stage treatment of prosthetic infections.

STATE OF THE PRIOR ART

It is known that joint prostheses can be colonized by bacteria and become infected.

In cases of infection, the infected prosthesis is removed from the site of infection and replaced by an antibiotic spacer device, in order to overcome the infection at the implant site, while maintaining substantially unchanged the shape of the bone seat or the joint seat in which the new prosthesis will subsequently be implanted.

Due to the fact that treatment of the infected socket occurs by inserting an antibiotic spacer and then reimplanting the new prosthesis, this procedure is known as "two-stage treatment".

Spacer devices are known, for example for the hip joint, which comprise a stem element, for coupling with the upper femoral end, removably associable with a ball or head element, which can be associated with the acetabular cavity.

These devices have an interchangeable and adjustable head on the stem element, so that the distance of the head from the stem itself varies.

The stem element has an end portion shaped substantially as a pin.

This pin can be housed within the head of the spacer device and the distance between the neck of the stem component and the head can be adjusted according to the patient's needs.

An example of a spacer device is described in international application WO2010/015877.

The coupling mechanism between the head and the stem element may be of the bayonet type, for example, especially in permanent prosthetic devices.

However, this type of coupling does not guarantee high durability over time. In fact, the components that determine the bayonet coupling, which are generally small in size, are subjected to concentrated pressures and forces of such size that they lead to the risk of breaking the same.

Furthermore, such a coupling mechanism is not easy to operate, it is not quick to use, and this can lead to prolonged implantation times for a device equipped with such a system.

In the case of a spacer device, since this is a temporary device, the surgeon feels the need to have a device capable of allowing a simple and rapid adjustment of the head on the stem element, while simultaneously ensuring good strength and durability over time of the device itself.

Furthermore, known spacer devices are made of porous material, so that they comprise or are impregnated with one or more medical or pharmaceutical substances to be released into the human body, in the anatomical area where their implant is provided.

However, the amount of medical or pharmaceutical substance that can be impregnated into the spacer device is limited, due in fact to the geometry and nature of the material that constitutes this type of device.

Therefore, the surgeon must provide a spacer device capable of comprising or housing one or more medical or pharmaceutical substances in specific parts thereof, possibly independent of each other.

OBJECTS OF THE INVENTION

The task of the present invention is to improve the state of the art.

Within the scope of said technical task, an object of the present invention is to provide a spacer device, for the treatment of an infected seat of the human body, which is easy and quick to use.

A further object of the present invention is to provide a spacer device that can be adjusted by the surgeon, directly in the operating room, based on the anatomical characteristics of the patient.

Another object of the present invention is to provide a spacer device having a coupling mechanism, between the head and the stem, which is strong and has a good durability over time. A further object of the present invention is to provide a spacer device for the release of a quantity of at least one medical or pharmaceutical substance in portions to ensure complete treatment of the infected site, also possibly over long periods of time.

In accordance with one aspect of the present invention, there is provided a stem element, according to claim 1.

In accordance with one aspect of the present invention, there is provided a spacer device, according to claim 3.

The dependent claims correspond to preferred and advantageous embodiments of the invention.

BRIEF DESCRIPTION OF THE DRAWINGS

Additional features and advantages of the present invention will become more apparent from the detailed description of a preferred but non-exclusive embodiment of a modular spacer device, illustrated by way of non-limiting example in the attached drawing tables, in which:

Figure 1 is a perspective view of a portion of a stem element and a partially sectioned head or ball element of a modular spacer device according to the present invention;

Figure 2 is a side view of a stem element of a modular spacer device according to the present invention;

Figure 3 is a top view along direction III of the stem element of Figure 2;

Figure 4 is a perspective view of a portion of a stem element of a modular spacer device according to the present invention;

Figure 5 is a front view of the stem element according to Figure 2 from another angle;

Figure 6 is a sectional view taken along the VIVI plane of Figure 2;

Figure 7 is a perspective view of a portion of a stem element and a portion of a head or ball element of a modular spacer device not in accordance with the present invention;

Figure 8 is a perspective view of a modular separator device according to another version of the present invention;

Figure 9 is a perspective view of a portion of a stem element and a portion of a head or ball element of a modular spacer device not in accordance with the present invention;

Figure 10 is a perspective view of a portion of a stem element and a portion of a head or ball element of a modular spacer device not in accordance with the present invention.

Figure 11 is a perspective view of a portion of a stem element and a portion of a head or ball element of a modular spacer device not in accordance with the present invention,

Figure 12 is a side view of a version of the modular spacer device according to the present invention, Figure 13 is a view of the version of Figure 12, in which the two elements constituting the spacer device are positioned mounted relative to each other at the maximum distance,

Figure 14 is a view of the version of Figure 12, in which the two elements constituting the spacer device are positioned so that they are mounted relative to each other at the minimum distance.

EMBODIMENTS OF THE INVENTION

As is known, a spacer device 1 is provided to be implanted in a bone or joint seat of the human body, replacing an infected prosthesis and for the treatment of said joint seat before reimplantation of a new prosthesis.

The spacer device 1 according to the present invention is of a temporary and disposable type.

In fact, this device carries out the treatment function, as well as the function of maintaining the shape of the bone or joint seat in which the new prosthesis is subsequently implanted.

With respect to the treatment function, said spacer device is adapted to treat an infection colonizing a bone or joint seat in which an infected prosthesis is housed, after the latter has been removed. Said function is carried out due to the release, by the spacer device, of one or more medical or pharmaceutical substances.

The spacer device 1 according to the present invention is of the "modular" type since it can be assembled by the surgeon directly in the operating room and can be adapted to the anatomical characteristics of the patient.

Reference will now be made to a modular spacer device 1 for the hip joint. However, the spacer device 1 according to the present invention can also be adapted to be implanted in a different bone seat, such as, for example, that relating to the shoulder joint.

The modular spacer device 1 comprises a stem element 2, adapted to engage a bone bed, and a head or ball element 4, adapted to be inserted into a joint area of the patient.

The spacer device 1 further comprises coupling means 3. The coupling means 3 are means for mutual positioning between the stem element 2 and the head 4, as will be further described below. The stem element 2 and the head 4 are removably connected to each other.

The coupling means 3 are positioned between the stem element 2 and the head 4 and are adapted to removably connect or position the stem element 2 to the head 4.

The stem element 2 comprises at least one distal end 2' and an elongated body CA.

The elongated body CA has, in one version, a shape that is substantially conical or truncated conical or with a truncated pyramid.

The elongated body CA has an external coupling surface 2", for coupling the spacer device 1 or at least a part thereof to the bone seat to be treated or to a part thereof.

The coupling surface 2" therefore has a shape substantially complementary to the bone seat in which the stem element 2 is implanted.

During use, the 2" mating surface is in contact with the patient's bone tissue.

This facilitates the correct positioning of the stem element 2 and its connection to the bone seat.

Referring to the embodiment illustrated in Figures 1-14, the engagement surface 2" is shaped so as to facilitate engagement of the stem element 2 to the femoral end of the hip joint.

In one version of the invention, the elongated body CA may comprise 4 faces, two substantially flattened faces and two substantially curved faces, one alternating with the other.

The two substantially flattened faces are placed on opposite sides with respect to a plane S of longitudinal symmetry of the elongated body CA or the stem element 2. The two substantially curved faces are substantially perpendicular with respect to the plane S.

The stem element 2 comprises at least one recess 8.

In one version of said spacer device, it comprises a plurality of recesses 8 positioned along or in the engagement surface 2". In particular, the at least one recess 8 may be positioned along or in the flattened faces of the elongated body CA of the stem element 2.

The stem element 2 may comprise recesses 8 extending more or less deeply within it and/or positioned according to an arrangement which may vary depending on the specific requirements.

In one version of the invention, the recesses 8 have a flat surface extension which is greater than the depth thereof.

Thus, due to this specific shape, it is possible to completely fill each recess 8 without running the risk of accidentally missing some parts of it from filling material. There is a risk of this happening, for example, when the recesses have a depth greater than their width or when the opening they determine on the surface of the medical device is limited. Indeed, in these cases, air bubbles could, for example, remain trapped inside the recess and this could prevent the latter from being correctly filled.

The at least one recess 8 in fact forms a seat for receiving a filling material comprising, in one version of the invention, at least one medical or pharmaceutical substance in the rod element 2 of the spacer device.

Therefore, depending on the severity of the infection present, all or only some of the voids can be filled with the filling material comprising the at least one medical or pharmaceutical substance and/or different pharmaceutical substances can be accommodated in the various voids, depending on the mode of spread of the infection in the joint site in question.

The recesses 8, in practice, act as seats for the storage of at least one medical or pharmaceutical substance to be released into the infected seat to be treated.

Said filling material, which contains at least one medical or pharmaceutical substance, may be of the hardenable or solidifiable type.

In one version of the invention, the filling material may be prepared by the surgeon during the operative procedure.

Such filler material may be free of medical or pharmaceutical substances and may be mixed with the same depending on the surgeon's selection and the patient's needs.

In a further version of the invention, the above-mentioned filling material may comprise at least one medical or pharmaceutical substance previously arranged in the material constituting the filling material itself, and possibly, during preparation, may be mixed with an additional substance.

Furthermore, due to the preparation and solidification stage to which it is subjected, the filling material may be porous.

The filling material, in one version of the invention, is a bone cement, a polymethyl methacrylate-based bone cement, or polymethyl methacrylate or a ceramic material. Therefore, the total volume of the recesses 8 or of the recess 8 is adapted for the estimated period of time to treat the ongoing infection in the seat in which the spacer device is placed.

The filling material is a biologically compatible material.

The size of the pores possibly present in the filling material or in the spacer device 1 is such that it prevents the growth of new bone during use within it and, therefore, within the spacer device, which, as indicated, is temporary.

Therefore, one of these pore configurations facilitates the subsequent removal of the spacer device itself from the treated bone or joint seat, once its treatment function is completed.

For example, the pores may, in one version, have dimensions on average less than 100 micrometers. Thus, the pores present in the filling material and/or in the spacer device perform a capillary function. The relative material, therefore, due to said capillarity, ensured by the size of the pores, can absorb at least one medical or pharmaceutical substance (present, for example, in liquid or solution form), hold it inside it and release it gradually over time.

In a further version of the invention, at least some of the voids 8, according to specific needs, can be filled or accommodate the filling material lacking medical or pharmaceutical substances.

If there are a plurality of recesses 8 along the coupling surface 2", a structure with open cells next to each other is obtained.

For example, each recess may have an external surface corresponding to 1/2 to 1/4 or even 1/6 to 1/8 of the surface of the face or of the surface on which it is present, for example, of the faces of the elongated body CA of the stem element 2.

As indicated, the recesses 8 are flat and are positioned at the interface with the bone tissue, in a particular manner, for example, for the stem element 2.

In one version of the invention, the filling material is a fluid and/or pasty mass, obtained by binding with bone cement one or more pharmaceutical or medical substances, such as one or more antibiotics, for example.

Thus, in the version where the filling material M comprises bone cement and the material from which the spacer device is made is bone cement, the fluid bone cement of the filling material fuses with the bone cement of the spacer device, making a perfect bond between them. Thus, there is no risk, for the patient, that the filling material separates from the respective spacer device, once the latter is implanted in the human body.

Furthermore, the flat profile of the recesses 8, as well as the presence of the ribs N, which are short continuous sections, allows easy filling of the recesses themselves with the filling material. Thus, as indicated, the latter can be easily leveled with the external surface of the spacer device or with the external surface of the ribs N, for example, due to the aid of a simple spatula. Such alignment is important to avoid possible excess thicknesses or discontinuities of fresh cement added by the physician, with the consequent impossibility of inserting the spacer device into the appropriate bone cavity or seat, such as the diaphyseal channel for the stem element 2.

A further aspect of at least one version of the present invention is that the spacer device 1 performs the mechanical function required for its use. Therefore, the material constituting it must be able to withstand the loads applied by the patient. However, said aspect does not relate to the filling material, the purpose of which is not structural or mechanical, but only that of a vehicle for the at least one medical or pharmaceutical substance.

Consequently, the filling material may comprise, in one version of the invention, more antibiotic than would be possible to insert into the material of the spacer device, in fact because, unlike the latter, it does not have to exert mechanical resistance.

In a further embodiment, a medical or pharmaceutical substance, such as at least one antibiotic, may be present in or miscible with the material constituting the spacer device. In this embodiment, this material is porous. This may possibly be bone cement or PMMA-based bone cement. If the teeth 5 and the seats 6, 6A are made of the same material, these are also porous and are provided with or miscible with at least one medical or pharmaceutical substance.

The recesses 8, as indicated, are separated from each other by ribs N interposed between the recesses 8 themselves: said ribs N are adapted to ensure a division between the recesses 8, such that the medical or pharmaceutical substances contained in the different recesses 8 do not come into contact with each other.

In one version of the invention, the ribs N are continuous and substantially rectilinear sections.

Furthermore, said ribs N can be adapted to improve the coupling of the coupling surface 2" to the bone seat to be treated, and/or to act as a reinforcing element for the stem element 2 itself.

Said ribs N, in one version of the invention, may be made of a material different from that constituting the stem element 2.

In one version of the invention, illustrated, for example, in Figure 2, each flattened face of the elongated body CA or at least a lateral portion thereof is affected by three recesses 8, separated by ribs N.

In particular, the ribs N may have an inclined, opposite progression with respect to the adjacent rib. For example, a first rib N, placed, for example, at the distal end or part 2' of the stem element 2, has substantially the same progression as a third rib N (separating a second recess 8 from a third recess 8), while a second rib N (separating a first recess 8 from a second recess 8) will have an opposite progression, and so on.

Each rib N is interposed between the recesses 8.

The thickness of the ribs N is less than the size (i.e. with respect to both length and width) of each recess 8. The thickness of the ribs N is that size which extends perpendicular to the largest size or extension thereof, the latter also called the length of the rib.

The depth of the ribs N corresponds to that of the adjacent recesses 8.

The stem element 2 may be made of biologically compatible, possibly porous material, for example made of polymethylmethacrylate (PMMA), polyvinyl chloride (PVC), polystyrene (PS), polyethylene (PE), ultra-high molecular weight polyethylene (UHMWPE), high or low density polyethylene, etc. or a bone cement or non-polymeric materials, ceramics, metals, metal alloys, metal-organic compounds and/or a combination thereof.

In one version of the present invention, the biologically compatible material is a polymethyl methacrylate (PMMA)-based bone cement.

In one version of the invention, the spacer device may have a metal core and an external coating based on bone cement. In the case of the recesses 8, these in said version are made in the bone cement layer, so that no metal portion of the spacer device 1 is exposed.

The biologically compatible material mentioned above may comprise at least one medical or pharmaceutical substance or may initially be devoid of medical or pharmaceutical substances. According to a further version of the present invention, the biologically compatible material may be a ceramic cement, such as calcium sulphate known as gypsum or CaSO4, which in addition to solidifying in limited times is capable of releasing calcium ions.

To manufacture the stem element 2, additional materials of a biocompatible type can also be used, with respect to what was described above, without departing from the protective scope of the present invention.

In one version of the invention, the biocompatible material is of a permanent type, that is, it cannot dissolve or degrade within the human body.

N-ribs can be made of biologically compatible and porous material, to be impregnated, in one version, with medical or pharmaceutical substances to be released into the infected bone site.

The distal end 2' of the stem element 2 comprises a stem 12.

Said rod 12 is adapted to engage with the head 4.

Said stem 12 is connected to the body CA of the stem element 2 at a flat base B of the latter. The stem element 2 comprises a portion P, at the distal end 2'. Said portion P is elongated and/or tapered and/or enlarged from the body CA of the stem element 2 towards the flat surface B, from which the stem 12 starts.

The portion P comprises a first end connected to the body CA and a second end constituted by the flat base B.

The flat base B, as indicated, is fixed to the stem 12.

According to the invention, the body CA, the portion P and the stem 12 are made of a single piece. In such a case, the stem element 2 is made of a single piece. In this version, also the coupling means 3, or at least a component thereof, can be made of a single piece with the stem element 2. Said aspect will be described in detail below.

According to the version illustrated in Figures 1-14, said rod 12 may appear in the form of a cylinder with height h and diameter d, which has a base area smaller than that of the flat base B on which said rod 12 is fixed or from which it departs.

According to one embodiment, the cylindrical stem may have a height h equal to 35 mm and a diameter equal to 16 mm. Furthermore, the stem 12 mentioned above comprises a lateral surface 2”' which may be smooth and/or rough. The stem 12 may have different geometric shapes, although always adapted to ensure the coupling function between the stem element 2 and the head 4.

In one version of the invention, therefore, the stem 12 may have, for example, the shape of a right prism or other geometric solid.

According to the illustrated embodiment, the head or ball element 4 may comprise at least one substantially hemispherical cap 9.

In one version of the invention, the head component 4 further comprises a projecting portion 10 which during use extends towards the distal end 2' of the stem element 2. The projecting part 10 is substantially annular.

The protruding portion 10 extends from the substantially hemispherical cap 9 or from a base thereof, giving a substantially "mushroom" shape to the head element 4.

In one version of the invention, the protruding portion 10 and the substantially hemispherical cap 9 of the head or ball element 4 are made of a single piece.

In a further version of the invention, said element has a substantially spherical shape. According to a further non-illustrated version, the head component 4 may only comprise a substantially hemispherical cap 9.

The head or ball element 4 and/or the substantially hemispherical cap 9 and/or, if present, the protruding portion 10 comprise an external surface I, placed in contact with or directed during use towards the bone tissue.

Said external surface I, in a non-illustrated version of the invention, may comprise at least one recess, having characteristics analogous to those of the at least one recess 8 described above present in the coupling surface 2" of the stem element 2.

Also said at least one recess 8 may contain a filler material that contains or does not contain at least one medical or pharmaceutical substance.

It is possible to provide at least two ball or head elements 4 and/or substantially hemispherical caps 9 having different diameters, so that the surgeon can select the size of said component that best suits the anatomical characteristics of the individual patient.

Similarly, it is possible to provide at least two stem elements 2 having different sizes, so that the surgeon can select the size of said component that best suits the anatomical characteristics of the individual patient.

The present invention, therefore, also relates to a kit comprising at least a pair of components of different sizes, so that the surgeon can select the size most suited to the specific needs.

The head or ball element 4 comprises a cavity or hole 7 for receiving the stem 12 of the stem element 2.

The cavity 7 comprises a lateral surface 7'. The surface 7' is internal.

Furthermore, the cavity 7 comprises a hole for the entry of the rod 12 into the head or ball element 4.

The inlet hole is delimited by a base surface 11, which is a surface connecting the external surface I with the lateral surface 7' of the head or ball element 4.

The cavity 7 of the head 4 has a configuration substantially corresponding to that of the stem 12 of the stem element 2, such that the stem 12 can be inserted at least partially into the cavity 7, thus causing engagement and adjustment of the position of the stem element 2 and the head or ball element 4.

Thus, when the stem 12 has the shape of a cylinder, the cavity 7 has the shape of a dome with a cylindrical base, with a height and diameter slightly greater than or equal to those of the stem 12 and/or the diameter d and height h of the stem 12 itself. In fact, the dimensions of the cavity 7 must be such as to allow insertion and coupling with the stem 12.

The coupling means 3, as also indicated above, are adapted to ensure a coupling between the head or ball element 4 and the stem element 2 and, more precisely, between the cavity 7 of the head and the stem 12. In particular, the coupling means 3 make it possible to stabilise, possibly temporarily, a specific position of the stem 12 relative to the cavity 7, i.e. the distance of the stem element 2 relative to the head or ball element 4. As will be better described below, said positioning is stably and definitively fixed by means of a fixing material. In such a way, the spacer device according to the present invention, having a certain position ensured by the coupling means 3, and a certain stability and a certain fixing of its components, given by the fixing material, will be adapted to withstand the required loads.

Said coupling means 3 allow an adjustment of the size of the spacer device 1 according to the anatomy of the patient. In more detail, said adjustment consists in varying the distance D (for example, represented in figure 8) between the head or ball element 4 and the stem element 2.

Therefore, said coupling means 3 allow to vary or adjust the distance D between the flat base B of the stem element 2 and the base surface 11 of the head or ball element 4. The coupling means 3 comprise at least one tooth 5 or a plurality of teeth 5 and at least one seat 6 or a plurality of seats 6, in which said one or more teeth 5 are adapted to be housed.

By varying the housing position of the teeth 5 in the seats 6, it is possible to vary the distance D mentioned above.

In one possible configuration, the teeth are placed on the lateral surface 2"' of the stem 12 and the seats 6 are made in the cavity 7 of the head 4, on the lateral surface 7' thereof. In a further configuration, not illustrated and not forming part of the invention, the teeth 5 are placed on the lateral surface 7', and protrude with respect to it, for example, protruding towards the inside of the head 4, while the seats 6 are made in the stem 12, on its lateral surface 2"'.

The teeth 5 comprise portions, possibly elongated, and projecting with respect to the surface on which they are placed, that is, with respect to the lateral surface 2™ of the stem 12. In at least one version not forming part of the invention, the teeth 5 have an elongated extension according to a direction parallel to the longitudinal axis or to the longitudinal axis of symmetry of the stem 12 and/or of the head 4.

The teeth 5 have an elongated extension according to a direction perpendicular to the longitudinal axis or to the longitudinal axis of symmetry of the stem 12 and/or the head 4.

In one version of the invention, the teeth 5 are placed parallel and at preset distances F from each other, so that the surgeon can decide the distance D to fit the spacer device 1 in the operating room. In fact, by knowing the measurement of the preset distances F between the various teeth 5, the surgeon decides in which seats 6 to accommodate the various teeth 5, so as to define the desired distance D based on the anatomical characteristics of the individual patient.

In the version of the invention illustrated in Figures 1-5 and 8, the teeth 5 are parallel to each other and have an annular shape.

In this version, the teeth 5 are placed around the stem 12, coaxial with the latter and protruding with respect to its lateral surface 2™; the seats 6 are corresponding annular cavities or grooves, made in the lateral surface 7' of the cavity 7 of the head or ball element 4.

In an alternative version not forming part of the invention, the teeth are rings parallel to each other, placed on the lateral surface 7' of the cavity 7 and protruding with respect to it, while the seats 6 are corresponding annular cavities made in the lateral surface 2 ™ of the stem 12.

In a further version not forming part of the invention, as illustrated in Figures 7 and 9-11, the teeth 5 are protruding portions, which protrude with respect to the surface on which they rest or from which they depart, of rectangular, oval, triangular or other elongated shape, distributed in rows or columns extending along the surface itself to which they are fixed or from which they depart. In such a case, the seats 6 have a shape and position complementary to those of the teeth 5, to ensure a coupling between the head 4 and the stem element 2.

Therefore, the teeth 5 and the respective seats 6 have, in said version, a substantially geometric solid shape, such as a prism or a cylinder.

Said geometric solid comprises two bases, one of which is fixed or made on the lateral surface 2™ of the stem 12 or on the lateral surface 7' of the cavity 7, wherein said bases have a polygonal or circular shape.

Said teeth 5 may comprise, in at least one version of the invention, the cutout 13 (for example, illustrated in figures 2 and 4, but also applicable to the other embodiments or versions of the present invention) adapted to improve and make more stable the coupling of the teeth 5 within the seats 6.

Said cutout 13 may be made of a different material with respect to that which constitutes the teeth 5.

Furthermore, the cutout 13 may be made of a flexible and mouldable material, adapted to fix the teeth 5 within the respective seats 6 and/or to allow their entry into the seats 6 themselves.

For example, said cutout 13 may be made of a deformable material or PVC or rubber.

The teeth 5 have a width L along the direction defined by the height h or along a longitudinal direction of the shank 12.

In one version of the present invention, the teeth 5 have a width L equal to 3 mm and/or project 2 mm with respect to the surface on which they are placed.

The teeth 5 may be made of the same material as the stem element 2 and/or as the head or ball element 4 and/or may be made in one piece with the same.

The teeth 5 may be made of biocompatible material, such as polymethyl methacrylate (PMMA), polyvinyl chloride (PVC), polystyrene (PS), polyethylene (PE), ultra-high molecular weight polyethylene (UHMWPE), high or low density polyethylene, etc. or a bone cement or non-polymeric materials, ceramics, metals, metal alloys, metal-organic compounds and/or a combination thereof.

In the embodiment illustrated in the figures, the teeth 5 and the seats 6 constitute a snap-type coupling mechanism.

In one version of the invention, when the coupling occurs under pressure, a material with elastic properties may be present in the at least one tooth 5 and/or in the at least one seat 6 and/or in the stem element 2 and/or in the head or ball element 4, said elastic material adapted to deform at least slightly to allow the adjustment of the at least one tooth 5 in the at least one seat 6, without creating cracks or damaging the material constituting the stem element 2 or the head or ball element 4.

In the version of the invention illustrated, for example, in Figure 1, the teeth 5 appear in the form of open rings, having at least one opening C along each tooth 5.

The opening C is a kind of recess with respect to the outermost surface of the annular teeth 5.

According to an embodiment not forming part of the invention, also the opening C can assist in the snap-fitting between the teeth 5 and the seats 6, since it can allow an elastic deformation of the teeth 5 when they are forced to penetrate inside the seats 6.

Said openings C are placed in the teeth 5 so as to be parallel to each other, in order to create a channel free of projections on the surface on which said teeth are placed. In such a way, the openings C are placed along a same axis, parallel to the longitudinal axis of the stem 12. In a further version, the openings C can be placed in an offset manner, that is, not aligned along a same axis parallel to the longitudinal axis of the stem 12.

In this version, the seats 6 may have an annular shape which is corresponding to but lowered with respect to the lateral surface 7' of the cavity 7.

According to the invention, the teeth 5 are placed parallel to each other and the space between the teeth 5, corresponding to the preset distance F of separation between them, constitutes at least one seat 6A. In said version, the teeth 5 appear in the form of open rings, having at least one opening C along each tooth 5.

The opening C is a kind of recess with respect to the outermost surface of the annular teeth 5.

In such a case, the cavity 7 may have a diameter or surface area slightly greater than or equal to that given by the sum of the measurement of the diameter d of the stem 12 and the measurement corresponding to the projection 105 of each tooth 5.

Furthermore, the cavity 7 has a projection 5A, with dimensions corresponding, at least with respect to the width, with respect to the dimensions of the opening C of the teeth 5.

In particular, the projection 5A has a height F or slightly less than F and a width 107 corresponding to the width of the opening C or slightly less than it.

During the stage of insertion of the stem 12 into the cavity 7, therefore, the projection 5A, having a suitable size, can pass along the channel determined by the opening C of each tooth 5. When the surgeon has established the correct distance D between the stem element 2 and the head or ball element 4, it is possible to rotate the stem element 2 relative to the head or ball element 4 (or vice versa), so as to allow the sliding of the projection 5A in the seat 6A formed by the space between one tooth 5 and the next.

It is therefore necessary that the projection 5A has a height (calculated along a direction parallel to the longitudinal axis of the stem 12) equal to or less than the distance F between one tooth and the next. If the teeth 5 have such a shape, the seats 6 may have the shape of, and/or the cavity 7 may have, one or more projecting parts 5A adapted to be introduced into the spaces present between one tooth and the next, possibly through the openings C, so as to obtain a coupling between the stem element 2 and the head or ball element 4.

In a particular version of the invention, at least two projections 5A may be present. In such a case, the projections 5A are aligned along a same longitudinal axis, parallel to the longitudinal axis of the stem 12 and/or to the longitudinal axis of the cavity 7. In such a case, also the openings C are aligned along an axis parallel to the longitudinal axis of the stem 12 and/or to the longitudinal axis of the cavity 7. In said version, the projections 5A are placed, with respect to each other, separated by a distance equal to or slightly greater than the width L of the teeth 5, so that they can be inserted into two adjacent seats 6A (which are separated, along a longitudinal direction parallel to the longitudinal axis of the stem 12, by a measure equal to the width L of the teeth 5).

According to the invention, therefore, the coupling means 3 comprise bayonet coupling means. The configuration of the modular spacer device 1, according to the present invention, allows a considerable increase in the strength and durability of the coupling means between the head and the stem. In fact, said coupling means comprise teeth that can be larger in size than those of known devices, possibly prosthetic ones, and, consequently, the pressures and forces to which said teeth are subjected are divided into large areas, which guarantees a lower probability of breakage thereof over time.

As is visible, for example, in Figure 2 (and also valid for other versions of the invention), considering the teeth 5 for the extension thereof away from the lateral surface 2™ of the stem 12, the teeth 5 have a section, taken along the longitudinal plane of symmetry of the stem element 2 , having a substantially rectangular or quadrangular shape. In particular, each tooth 5 projects at a distance 105 from the lateral surface 2™ of the stem 12. Furthermore, each tooth has a height 106 (or width L), considered along the longitudinal direction of the stem 12.

In one version of the invention, the height 106 may vary from tooth to tooth.

In a further version, the teeth 5 may have a semicircular or triangular section and/or a section with rounded edges.

However, in one version of the invention, the rectangular or quadrangular section confers greater stability of connection or union with the head or ball element 4. Naturally, the possible housing seats 6 for the teeth 5 have a shape corresponding to that of the teeth 5 themselves.

Furthermore, in at least one version of the invention, approximately 3 to 7 teeth 5, preferably 5, are present, positioned starting from the top of the stem 21 to the area thereof closest to the base B of the stem element 2.

Furthermore, the teeth may be present in a number of rows varying from 3 to 7, preferably 5 rows.

There may be the same number of seats 6 and teeth 5 possible, or the same number of rows of teeth 5.

The projection 5A, in the version illustrated in Figures 12 to 14, is placed at a distance 108 from the surface 11 of the head or ball element 4. In particular, the lower surface of the projection 5A is located at the distance 108 from the surface 11.

The projection 5A is therefore positioned in the area of the head or ball element 4 closest to the opening delimited by the surface 11.

In the version not forming part of the invention in which the projection 5A is placed on the lateral surface 2™ of the stem 12 and the teeth 5 and the seats 6A are placed on the internal surface of the cavity 7, the projection 5A will be located at a distance 108 from the apical portion of the stem 12, or at least in the area closest to the apical portion of the stem 12 itself. In such a way, the openings C themselves would be positioned in the teeth 5 of the head 4. In such a way, it is possible to couple the stem element 2 and the head or ball element 4 at a maximum distance D, so as to allow in any case a stable coupling, in which the projection 5A is housed in the seat 6A closest to the apical part of the stem 12, as visible in figure 13.

Furthermore, it is possible to couple the stem element 2 and the head or ball element 4 at a minimum distance D, in which the projection 5A is housed in the seat 6A closest to the base B of the stem element 2, as seen in figure 14. In such a position, the distance D may be zero and the base B may be in contact with the surface 11 of the head or ball element 4.

Naturally, all intermediate positions are possible between the maximum distance D and the minimum distance, discretely according to the number of seats 6A or seats 6 present, so as to meet the anatomical needs of the patient.

In yet a further version of the present invention, not illustrated in the figures, in addition to the teeth 5, the seats 6A and the projection 5A, additional seats 6 could be present, to accommodate the teeth 5. In such a way, the coupling means 3 could be both a snap-in coupling and a bayonet coupling.

The projection 5A has a section corresponding to that of the seats 6A in which it is inserted, for example, in the version in which the teeth 5 have a rectangular or quadrangular section, the seats 6A have a rectangular or quadrangular section and similarly the projection 5A also has said rectangular or quadrangular shape or section.

Therefore, the coupling means 3 include at least one tooth 5, at least one projection 5A and/or at least one seat 6, 6A.

The teeth 5, in any case, determine the relative position between the neck and the head of the spacer device 1 according to the present invention. However, the teeth 5 do not determine the final fixing between the parts, a fixing which is determined by the presence of a fixing material or glue means or final fixing means, which is able to make the position defined by means of the teeth 5, or generally the coupling means 3, permanent.

In fact, once the components constituting the spacer device 1 are assembled, said assembly is definitively fixed through a fixing material, such as bone cement, glue material, monomers or others, possibly allowing at least a superficial fusion of the material constituting said components and obtaining a sort of single body.

Therefore, the fixation material can be of a different nature. For example, acrylic bone cement, or a cyan-acrylic glue, or an organic solvent, or a multi-component mixture such as chloroform, methyl methacrylate, ethyl acetate, dichloromethane and not only or at least one of them can be used. Of course, whatever glue medium is used, it must be stable and biocompatible.

The fixing material, once inserted, penetrates between the seats or channels of the coupling means 3 and locks the stem element 2 with the head or ball element 4 in position, such that it is no longer possible to rotate one with respect to the other, or to modify the distance between them. In this way, a stable fixation or coupling is created, to make the spacer device suitable for implantation.

In such a way, a stable and secure coupling between the two elements of the spacer device 1 is ensured. According to one version, the fixing material is inserted or poured into the cavity or hole 7 of the head or ball element 4. Subsequently, the stem 12 of the stem element 2 is inserted into the cavity or hole 7. In such a way, the fixing material will completely cover the surfaces of the stem 12 and/or the cavity 7, and/or fill possible empty spaces thereof, as well as possibly the 6, 6A.

In this way, a mechanically solid and consolidated fixation is obtained between the two components of the device 1.

The subject of the present invention is also a method for assembling the device 1 according to the present invention. Said method provides for the supply of a spacer device 1 comprising a head or ball element 4 and a stem element 2 equipped with a stem 12. The head or ball element 4 comprises a cavity or hole 7 for receiving the stem 12 of the stem element 2.

The method therefore enables the stem 12 to be at least partially inserted into the cavity 7.

In this way, the coupling and adjustment of the position of the rod element 2 and the head or ball element 4 is determined.

In particular, the method also provides a step of supplying coupling means 3, adapted to ensure a coupling between the head or ball element 4 and the stem element 2 and, more precisely, between the cavity 7 of the head and the stem 12.

In one version of the invention, the coupling means 3 are made in one piece, respectively, with the stem component 2 or with the head or ball element 4.

As can be inferred from the above description, in order to establish such an adjustable connection between the stem element 2 and the head or ball element 4, it would be possible to have only one tooth 5 and a plurality of seats 6 or a projection 5A and a plurality of seats 6A between the teeth 5 having an open annular shape.

However, in at least one version of the invention, when multiple teeth 5 are inserted and/or connected into multiple seats 6, greater coupling stability is achieved and there is a lower risk of having an accidental disconnection between the two components.

The method then provides for the supply of coupling means 3 comprising at least one tooth 5 or a plurality of teeth 5 and/or at least one projection 5A and at least one seat 6, 6A or a plurality of seats 6, 6 in which said one or more teeth 5 and/or said at least one projection 5A are adapted to be received.

The method then provides for inserting one or more teeth 5 into one or more seats 6 in such a manner as to removably connect the stem element 2 or the stem 12 with the head or ball element 4, or with its cavity 7. The insertion of one or more teeth 5 into one or more seats 6 may determine a snap-in coupling.

This snap-in coupling is removable.

The surgeon, with the spacer device 1 according to the present invention, can select which tooth 5 to insert into which seat 6, or into which seat 6A to insert the projection 5A, to adjust the distance D between the stem element 2 and the head or ball element 4 or between the flat base B of the stem element 2 and the base surface 11 of the head or ball element 4.

For example, with respect to one version of the invention, the method provides for the supply of a plurality of open ring-shaped teeth 5, having at least one opening C along each tooth 5 and at least one seat 6 possibly with a projection shape adapted to be inserted into the opening C of the teeth 5. Said openings C are positioned in the teeth 5 to be parallel to each other, to create a projection-free channel on the surface on which said teeth are placed.

In one version, the method provides for inserting at least one projection 5A into at least one opening C and then into at least one seat 6A and rotating the two components relative to each other, to connect the stem element 2 or the stem 12 to the head or ball element 4, or to its cavity 7.

The insertion of at least one projection 5A into at least one seat 6A may determine a bayonet coupling.

This type of coupling is also removable.

In particular, the projection is inserted into the opening C present in the teeth 5 and is made to slide to the desired distance from the flat base B of the stem element 2. Once said distance is reached, the head or ball element 4 is rotated to make the projection penetrate and slide into the space between a tooth 5 and the subsequent tooth.

In this way, the connection and coupling of the rod element 2 and the head or ball element 4 of the spacer device 1 is determined, simultaneously adjusting the distance D between said two elements.

In this way, it is also possible for the relative teeth 5 to be inserted into suitable seats 6 which are sunken with respect to the surface on which they are made.

Furthermore, once the stem element 2 and the head or ball element 4 are assembled, the method provides for supplying a fixing material into the stem 12 and/or into the cavity 7, in such a manner as to fix the selected position. Said fixing comprises a gluing step, for example by means of a fixing material, such as cement, glue material, monomers or others.

In addition, in one version of the invention, the method provides for the application of the filling material into the at least one recess 8. The surgeon can select which medical or pharmaceutical substance to insert into the filling material and into which of the recesses 8 to apply said substances. In this way, the one or more recesses 8 are filled with filling material, obtaining a smooth and continuous external surface with respect to the coupling surface 2" of the stem element 2 and/or to the surface I of the head or ball element 4.

In a further version of the present invention, the filling material, and possibly the one or more medical or pharmaceutical substances contained therein, may already be arranged in the at least one recess 8 of the spacer device 1 by the producer of said device.

Furthermore, if necessary, a step for dipping or impregnating or mixing a medical or pharmaceutical substance into the material from which the spacer device 1 is manufactured may also be provided.

Therefore, the spacer device may contain or be adapted to contain a medical or pharmaceutical substance, which may be equivalent to or different from that contained in the filling material accommodable in the at least one recess 8.

As described above, it follows that the spacer device according to the present invention can be customized by the surgeon according to the patient's needs. For example, the surgeon can, if necessary, apply to the spacer device all the medical or pharmaceutical substances necessary to overcome the ongoing infection in the bone seat of the implant, housing each one in one or more recesses, so that they are kept separate from each other but present in the same device, to transmit each substance to the affected area or to transmit the various substances to the bone or joint seat, without having to mix them or apply them together.

Furthermore, since the opening of the at least one recess is flush with the surface of the spacer device or is flush with the outer edge of the ribs N, the filling material is in turn placed flush with said surfaces, so as not to alter the desired shape of the spacer device, that is, that shape that allows its implantation.

The invention thus conceived is susceptible to numerous modifications and variations, all of which are within the scope of the inventive concept.

The features presented for one version or embodiment may be combined with the features of another version or embodiment, without departing from the protective scope of the present invention.

Claims (19)

1. A stem element (2), suitable for constituting at least a part of a modular spacer device (1 ), implantable in the human body for the treatment of an infected joint seat, wherein said stem element (2) comprises coupling means (3), wherein said stem element (2) comprises a distal end (2'), an elongated body (CA) and a portion (P) at the distal end (2'), and at least one external coupling surface (2"), wherein said distal end (2') is suitable for being faced, during use, towards an additional component of a spacer device and said coupling surface (2") is suitable for coupling, during use, to a bone bed, wherein said distal end (2') comprises a stem (12 ) connected to said stem element (2) at a flat base (B) of said stem element (2), wherein said portion (P) is elongated and/or tapered and/or enlarged proceeding from the body (CA) of the stem element (2) towards the base (B) of the stem element (2). flat (B), from which the stem (12) starts, characterized in that said coupling means (3) comprise at least one tooth (5) placed on a lateral surface (2” ') of said stem (12) and having an open annular shape with an opening (C) coaxial with said stem (12), where said at least one opening (C) determines a channel for the insertion of at least one projection (5A) of the additional component of a spacer device suitable for making a bayonet coupling, and because said body (CA), said portion (P) and said stem (12) are made of a single piece and said stem element (2) is made of a single piece. 2. Stem element according to the preceding claim, comprising at least one recess (8) for receiving a filling material comprising at least one pharmaceutical or medical substance, wherein said at least one recess (8) is positioned on said external coupling surface (2") and wherein each recess (8) is separated from an adjacent recess (8) by means of continuous and rectilinear sections or ribs (N). 3. Modular spacer device (1), implantable in the human body for the treatment of an infected joint seat, comprising a stem element (2) according to claim 1 or 2 and a head or ball element (4), wherein said stem element (2) can be coupled to a bone bed and said head or ball element (4) can be inserted into an area of the joint seat of the patient, wherein said stem element (2) can be removably connected by means of said coupling means (3) to said head or ball element (4), wherein said coupling means (3) are positioned between said stem element (2) and said head or ball element (4), wherein said coupling means (3) further comprise at least one seat (6, 6A), wherein said at least one tooth (5) and/or said at least one protrusion (5A) is adapted to be received within said at least one seat (6, 6A), such that the distance (D) between said head or ball element (4) and said joint seat (6, 6A) varies. stem (2) depending on the anatomical characteristics of the patient. 4. Modular spacer device according to claim 3, wherein said modular spacer device (1) comprises a fixing material, suitable for stably and definitively fixing said distance (D) of said stem element (2) with respect to said head or ball element (4). 5. Modular spacer device (1) according to claim 3 or 4, wherein said distal end (2') is adapted to engage with said head or ball element (4). 6. Modular spacer device (1) according to any of the preceding claims when they depend on claim 3, wherein said head or ball element (4) comprises a cavity (7) for housing said rod (12), wherein said cavity (7) comprises a lateral surface (7') and/or wherein said rod (12) comprising said lateral surface (2” ') has a configuration corresponding to that of said cavity (7). 7. Modular spacer device (1) according to any of the preceding claims, wherein said flat base (B) of the stem element (2) and a base surface (11) of the head or ball element (4) are positioned at a distance (D), wherein said coupling means (3) are adapted to vary or adjust said distance (D). 8. Modular spacer device (1) according to any of the preceding claims, comprising a plurality of teeth (5) and/or projections (5A) and/or a plurality of seats (6, 6A) such that by varying the connection or coupling position of said teeth (5) and/or projections (5A) in said seats (6, 6A) it is possible to adjust the distance (D) between said head or ball element (4) and said stem element (2). 9. Modular spacer device (1) according to the preceding claim, wherein said plurality of teeth (5) comprises teeth (5) placed parallel and at preset distances (F) from each other. 10. Modular spacer device (1) according to any of the preceding claims, wherein said at least one seat (6) is obtained on said lateral surface (2''') of said rod (12) and said at least one projection (5A) is obtained on said lateral surface (7') of said cavity (7). 11. Modular spacer device (1) according to any of the preceding claims, wherein said rod (12) has a cylindrical shape with height (h) and diameter (d) and wherein said cavity (7) has a dome shape with a cylindrical base with height and diameter slightly greater than or equal to said diameter (d) and height (h) of said rod (12). 12. Modular spacer device (1) according to any of the preceding claims, wherein said at least one tooth (5) has said annular shape and said at least one seat (6, 6A) comprises an annular cavity and/or wherein said at least one tooth (5) comprises a cutout (13) adapted to improve and make more stable and/or easier the coupling of said at least one tooth (5) in said at least one seat (6). 13. Modular spacer device (1) according to any of the preceding claims, wherein said at least one tooth (5) has a rectangular, oval, triangular or other shape and/or wherein said plurality of teeth (5) are arranged in rows or columns. 14. Modular spacer device (1) according to any of the preceding claims, wherein said head or ball element (4) comprises at least one recess (8) for housing a filling material comprising at least one pharmaceutical or medical substance. 15. Method for assembling the modular spacer device (1) implantable in the human body for the treatment of an infected joint seat according to any of the preceding claims when dependent on claim 3, comprising the steps of providing a head or ball element (4), a stem element (2) provided with a stem (12) at a distal end (2 ') of said stem element (2), and coupling means (3), wherein said head or ball element (4) comprises a cavity or hole (7) for receiving said stem (12) of said stem element (2), wherein said coupling means (3) are positioned between said stem element (2) and said head or ball element (4), wherein said stem element (2) comprises at least one distal end (2'), an elongated body (CA) and a portion (P) at the distal end (2'), wherein said portion (P) is elongated and/or tapered and/or enlarged from the body (CA) of the stem element (2) towards a flat surface (B), from which the stem (12) departs, wherein said body (CA), said portion (P) and said stem (12) are made of a single piece, and said stem element (2) is made of a single piece, removably connecting said stem element (2) by means of said coupling means (3) to said head or ball element (4), said coupling means (3) comprising at least one tooth (5) and/or at least one projection (5A) and at least one seat (6, 6A), by at least partially inserting said stem (12) into said cavity (7), housing said at least one tooth (5) and/or said at least one projection (5A) within said at least one seat (6, 6A), such as to vary and/or select the distance (D) between said head or ball element (4) and said stem element (2) according to the anatomical characteristics of the patient, providing a fixing material on said stem (12) and/or in said cavity (7), such as to stably and definitively fix said selected distance (D) of said stem element (2) with respect to said head or ball element (4). 16. Method according to claim 15, comprising a step of selecting at least one tooth (5) and inserting said at least one tooth (5) into at least one predetermined seat (6), or comprising a step of selecting at least one seat (6A) and inserting said at least one projection (5A) into said seat (6A), so as to adjust and/or select the distance (D) between said stem element (2) and said head or ball element (4) or between a flat base (B) of said stem element (2) and a base surface (11) of said head or ball element (4). 17. Method according to any of claims 15 or 16, comprising the steps of providing a plurality of open ring-shaped teeth (5), having at least one opening (C) along each tooth (5), wherein said teeth (5) are separated by at least one seat (6A) and at least one projection (5A) adapted to be inserted into the opening (C) of said teeth (5), inserting said projection into said opening (C) and causing it to slide to the desired distance from said flat base (B) of said stem element (2), once said distance is reached, rotating said head or ball element (4) so as to cause said projection to penetrate and slide into said seat (6A), i.e. into the space between said tooth (5) and the rear tooth (5), so as to adjust the distance (D). 18. Method according to any of claims 15 to 17, comprising a step of applying a filling material in at least one recess (8) positioned in said stem element (2) and/or in said head or ball element (4)), filling said at least one recess (8) with said filling material, hardening or solidifying said filling material. 19. Kit comprising a spacer device according to any one of claims 3 to 14, comprising a plurality of stem elements (2), each having a specific size and/or a plurality of head or ball elements (4), each having a specific diameter or size.