Patent Application
20240197481
The present invention relates to a mold for obtaining a spacer device, or part thereof, as well as a method for using such a mold and extracting an element molded therein.
Molds have been proposed for the realisation of joint spacer devices, which are usually made of elastically deformable material, such as silicone or other suitable elastomer material, and intended to be filled with bone cement added with antibiotic or other therapeutic substance, when this is in the phase of fluid and malleable mass, in order to obtain a finished spacer device.
After being hardened in such a mold, the bone cement added with an antibiotic or other therapeutic substance is subsequently removed from it and the resulting joint spacer, once finished, is implanted in the joint space of a patient to treat an ongoing disease in the tissues surrounding that joint space.
Traditional molds have numerous drawbacks.
First, at the end of the molding process, the spacer device may remain attached to the mold material, making it difficult to extract the spacer device quickly and easily.
Moreover, although in most cases these molds are meant to be recycled/disposed of after only one use, they are sometimes reused after a suitable washing process in order to reduce the costs of obtaining spacer devices of the same shape.
It may be the case, however, that such washing does not completely remove traces of antibiotic or therapeutic substances added to the bone cement used for a previous spacer device. This may result in allergic reactions to spacer devices made with an antibiotic to which a patient is not allergic but which have been made in a mold previously used with bone cement containing an antibiotic to which the patient is allergic.
Moreover, the polymerisation of the cement used for the realisation of spacer devices involves an exothermic reaction that brings the cement and the mold material beyond 100° C., while the steam sterilisation (a typical hospital system) used in the possible reuse of the molds brings the molds themselves to about 121° ° C.
As will be understood from the ensuing disclosure, the succession of heating measures at such high temperatures deforms the live areas of the molds, preventing the repeated formation of perfect spacers or compliance with the necessary requirements.
US2019134858A1 discloses a prior art solution.
An object of the present invention is to provide a new mold for obtaining a spacer device or a part thereof.
Another object of the present invention is to provide a mold as indicated above capable of ensuring easy and fast extraction of a spacer device molded therein.
Yet another object of the present invention is to provide a mold as indicated above that contains elements such as to ensure that it is used only once.
In accordance with one aspect of the invention, a mold is provided according to claim 1.
Dependent claims refer to preferred and advantageous examples of embodiments of the invention.
Other features and advantages of the invention will become more evident from the disclosure of exemplary embodiments of a mold, illustrated by way of example in the accompanying drawings, wherein:
In the accompanying drawings, identical parts or components are identified by the same numerals.
With reference to
Naturally, a mold according to the present invention can also be used for obtaining a spacer device of a different type, such as a hip or shoulder spacer device.
As is standard practice, spacer devices are temporary, disposable apparatuses implanted in the human body, for example at a joint in the human body, to replace a permanent joint prosthesis. This is basically because the implant of the permanent joint prosthesis is infected and it therefore becomes necessary, on the one hand, to treat the infection after removing the infected prosthesis and, on the other, to protect the joint space until a new prosthesis is implanted in the point from which the infection has been removed.
These functions are performed by the spacer devices, which are made of a suitable biocompatible material, such as a bone cement based on an acrylic resin, for example polymethyl methacrylate, possibly with the addition of at least one medical substance with an antimicrobial effect (for example, at least one antibiotic to treat the infection at the implant site). The most commonly used antibiotics are one of gentamicin or vancomycin or combinations thereof. This material, in at least one version of the invention, comprises bone cement, based, for example, on polymethyl methacrylate (PMMA).
The antibiotic or blend of antibiotics is mixed with bone cement by the doctor on the basis of, for example, the indications of the pharmacologist who will have evaluated the specific bacterial or pathogenic flora of the patient. The resulting material or mass is used to form the most effective spacer device for eradicating the infection in the specific patient.
The material that constitutes the mold, although rigid, is free of additives that can be extracted and/or absorbed by the bone material or cement that will constitute the spacer device during manufacture. The extraction and/or absorption of the additives present in the mold is a very serious problem that arises, for example, in molds made of elastomers, such as silicone, and so forth. As is evident, if the material of the molded spacer device has in its mass any additives extracted and/or absorbed by the material constituting the mold, this undermines the safety of the spacers molded with such molds from a toxicological point of view. Since early 2018, many molds of this type have been withdrawn from the global market.
A mold 1 according to the present invention comprises, in detail, a first half-shell 2 including or delimiting a first forming surface 2a delimited by a first perimeter or peripheral or ring-shaped edge 2b and intended to shape at least one first portion, or rather, at least one first face, of the spacer device TS.
The mold then comprises a second half-shell 3 including or delimiting a second forming surface 3a delimited by a second perimeter or peripheral or ring-shaped edge 3b and intended to shape at least one second portion or face of the spacer device TS.
The two half-shells 2, 3 are adapted to be coupled in use in a removable way so as to define a closed configuration for the mold and to delimit between them, at the first forming surface 2a and the second forming surface 3a, a molding cavity C1, for example a main molding cavity C1, corresponding to the external configuration of the spacer device TS, or of a part thereof, to be formed.
The two half-shells 2, 3 are then movable between an open configuration, for loading the material to be molded or for removing the molded spacer device, and a closed molding configuration.
The first forming surface 2a and/or the second forming surface 3a constitutes/constitute the area of application of the material that will constitute the spacer device to be formed with the mold 1 according to the present invention and are respectively intended to shape at least one first face and at least one second face of the spacer device TS.
With particular reference to
The upper face TS2 is adapted in use to be articulated with a femoral knee spacer device or with the femoral end of a knee joint of a patient, while the lower face TS1 is adapted in use to be implanted at the end of the patient's tibial bone at the knee joint.
If desired, the first forming surface 2a and/or the second forming surface 3a is also adapted to form a third portion or face, for example lateral TS3 (defining, in fact, the thickness) of a tibial knee spacer device TS.
Clearly, the first perimeter edge 2b is adapted to abut and come into contact, in use and more particularly in the closed configuration, with the second perimeter edge 3b.
Moreover, the mold 1 comprises at least one extractor component 4 intended to remove a spacer device TS, or a part thereof, formed in the mold 1 when the latter is in an open configuration, with the first half-shell 2 moved away from and not in contact (see
The extractor component 4 is, of course, a mechanical structural component and not a chemical compound applied on the forming surfaces 2a, 3a or on the delimiting walls of a molding cavity C1, C2.
Preferably, the extractor component 4 is integrated and, if desired, constrained or removably or non-removably connected to a respective semi-mold 2, 3.
Advantageously, the extractor component 4 is movable between a rest position and at least one extraction position in the direction going from within a respective half-shell 2, 3 towards the respective forming surface 2a, 3a, so as to determine the detachment of a spacer device from the latter. In essence, the spacer device 4, 104 does not act beginning from the forming surface 2a, 3a and moving towards the inside of the respective half-mold 2, 3, but rather from the inside of the latter towards the respective forming surface 2a, 3a.
Even more advantageously, the extractor component 4 is housed in a seat 5 delimited by said first half-shell 2 or by said second half-shell 3 and is mounted in a movable way in said seat 5 between a rest position, in which it does not protrude within said at least one molding cavity C1, C2 (which will be discussed in more detail later) or relative to a respective forming surface 2a, 3a, or else protrudes therein by a first magnitude and at least one extraction position in which it protrudes at least partially within a molding cavity C1 or C2 or relative to a respective molding surface 2a, 3a by a greater magnitude than the rest position.
Preferably, the extractor component 4 has first engagement means 6, while a respective half-shell 2, 3 has at the seat 5 second engagement means 7 designed to engage with the first engagement means 6 at least when the extractor component 4 is moved from the rest position to at least an extraction position. In this regard, advantageously, the engagement between the first 6 and the second 7 engagement means prevents or limits the return of the extractor component 4 to the rest position.
If desired, the first engagement means 6 can comprise first teeth or projections or recesses, while the second engagement means 7 can comprise second recesses or openings or protuberances for engagement of the first engagement means.
Clearly, more engagement means 6, 7 may be provided, so as to ensure a greater number of points or areas of non-return of the extractor component.
It is also possible to provide third engagement means 60 in or of the extractor component 4 that can be engaged with engagement means of a respective half-shell 2, 3, such that the extractor component 4 is prevented from moving away from the molding cavity C1, C2 or the respective forming surface 2a, 3a in the rest position. With regard to this possibility, mounting the extractor component 4 in the seat 5 could determine the engagement between the third engagement means 60 and second engagement means of a half-shell 2, 3, which would prevent a displacement, as now indicated.
With reference to this aspect, the third engagement means 60 can comprise third teeth or projections or recesses which can also be engaged with the second engagement means 7, including second recesses or openings or protuberances for engagement of the third engagement means.
In the rest position, the extractor component 4 is preferably unable to determine the detachment of a spacer device TS from the surfaces of the mold 1. Advantageously, the seat 5 is, on the one hand, open towards the forming surface 2a, 3a of the respective half-shell 2, 3 and, on the other, towards the outside of the mold 1, so that, from outside the mold 1, the extractor component 4 can be manually pressed or moved or controlled to take it from a rest position to an extraction position.
Optionally, the extractor component 4 has a base portion 4a and a stem portion 4b extending from the base portion and designed to engage a spacer device TS, or a part thereof, formed in the mold.
If first engagement means 6 are present, they can be formed in the stem portion 4b. The same applies to any third engagement means 60.
In this respect, one of the half-shells 2, 3 may delimit an opening or through hole 2p leading into a molding cavity C1 or C2 or into a respective forming surface 2a, 3a. In said opening or through-hole, the portion or stem 4b is also slidably inserted, with teeth 6 designed to define shoulders 6a facing away from said at least one cavity C1 or C2 and designed to abut against internal sections of the half-shell zone 2, 3 that delimit the opening or through-hole 2p. The same applies to any third engagement means 60.
Conversely, the engagement means may consist of one, two, three or more teeth, ring-shaped or otherwise, formed on the stem portion 4b. If several teeth are provided, they may be spaced along the extension of the stem portion 4b. Advantageously, the stem portion 4b has, between its free end 4b1 and a first tooth 6 or shoulder 6a, ring-shaped or otherwise, an increasing cross-section and the same applies in any sections between adjacent and subsequent shoulders 6a.
If several teeth are provided, then the tooth or teeth 60 near or closest to the free end 4b1 act(s) as third engagement means, while the next tooth or teeth act(s) as first engagement means 6.
In this case, the sections of the half-shell 2, 3 defining the opening or through hole 2p are elastically yielding, so that, by inserting the stem portion 4b, the latter enlarges the opening or through hole 2p until a shoulder 6a reaches and overcomes the latter, when the tooth 6, or rather, the respective shoulder 6a, engages by snapping onto the internal sections 7 of the zone of the half-shell 2, 3 delimiting the opening or through hole 2p.
In such circumstances, it would be difficult, if not impossible, to move the extractor component 4 backwards, since the teeth 6 would substantially prevent such movement, unless special tools were used and by means of difficult manoeuvres.
Clearly, there could also be an inverse structure to the one here disclosed, with one or more openings in the stem portion 4b and with teeth or projections in one of the half-shells 2, 3, for example starting from a delimiting wall of an opening or through hole defined by one of the half-shells.
As will become clear below, and as already partly indicated, the extractor component 4 has the function of extracting the spacer device once the latter has been formed and the material of which it is composed has hardened.
Preferably, as indicated above, the extractor component 4 is of a substantially unidirectional type, so that it has a non-return geometry that makes the mold 1 disposable.
This aspect is very important because, after having produced a spacer device, the mold might undergo changes or alterations caused precisely by the polymerisation and/or hardening reaction of the material that constitutes the device itself and which could compromise the correct functioning of the mold during subsequent uses. Such a mold should therefore not be re-used more than once. In addition, in the event of use, it would be necessary to sterilise the two half-shells and the other components, and the sterilisation phase might also cause modifications or alterations that could compromise correct functioning.
Moreover, only the use of a disposable mold ensures optimal sterility of the spacer device obtained with it.
In at least one version of the invention, the two half-shells, or rather, the respective forming surfaces differ from each other and do not mirror each other.
With reference to the step of obtaining or forming a spacer device, the first half-shell 2 can also be a lower body in use, while the second half-shell 3 can also be an upper body in use, considering the support plane on which the mold 1 in closing configuration can rest during the step of forming the respective spacer device TS. The second half-shell 3 can therefore act as a cover for the first half-shell 2.
During the forming phase, the mold 1 is therefore in a closed operating configuration. Conversely, during the loading phase of the material that constitutes the spacer device the mold is advantageously in an open operating configuration. In the open configuration, the first 2 and the second 3 half-shells can both rest on a support plane and/or be placed side by side.
If desired, the mold 1, if provided for making a knee spacer device with a stem TS4, can delimit a special secondary molding cavity C2 (seen, for example, in
In this case, therefore, the cavity C1 delimited between the first 2a and the second 3a forming surface substantially determines the formation of the tibial plate TS5 that has a substantially rectangular or oval or C shape in the plan view and a thickness given by the distance between the lower face TS1 and the upper face TS2 of the spacer device TS, while the secondary cavity C2 substantially determines the production of the stem TS4 of the spacer emerging from the tibial plate TS5.
However, the main cavity C1 and the secondary cavity C2 are contiguous to each other and/or in fluid connection, so that the material that goes to form the spacer device TS can flow (during the forming step) into both such cavities C1, C2 and form, in one step, both the tibial plate TS5 and the stem TS4 of the spacer device TS, which constitute one piece.
If desired, a handle 8, possibly removable, is present at one of the half-shells 2, 3 of the mold 1.
The surgeon or the personnel in charge of producing or forming the spacer device TS by means of the mold 1 may use this handle 8 to bring the first half-shell 2 into abutment against the second half-shell 3 (or vice-versa) and to apply adequate force to compress the material that will constitute the spacer device itself.
Indeed, the mold 1 is preferably not an injection mold and loading of the material into the mold 1 will be illustrated in greater detail in the continuation of the present disclosure.
The first half-shell 2 and/or the second half-shell 3 may have a substantially block-like or a solid or empty body conformation, for example substantially box-like or tub-shaped or polyhedral, possibly parallelepipedal or rectangular or cylindrical.
The walls (in the case of a box-like body) or faces (in the case of a solid block) of the half-shells 2, 3 can, for example, be substantially triangular, square or rectangular, possibly with bevelled edges. More particularly, two walls or faces are of larger dimensions and lie on two planes parallel to each other and parallel to the support plane on which the mold 1 is adapted to be placed, while the other at least three walls or faces (four in the attached Figures) constitute the lateral extension that perimetrically connects the two walls or faces of greater dimensions, for example in a substantially perpendicular manner to the latter.
Conversely, in the case of a cylindrical conformation of one or both half-shells, there are two substantially larger, circular or oval faces and a side wall or face, possibly tubular, extending from the perimeter or circumference of at least one of the larger walls or faces to the other.
With specific reference to the exemplary embodiment illustrated in the Figures, the first half-shell 2 comprises at least one first wall or main face, for example upper 2c in use, wherein the first forming surface 2a is defined or delimited and a lateral extension 2d consisting of one or more walls or side faces, preferably extending from an outer edge of the main face 2c.
In this case, the seat 5 is delimited in the area defined between the first wall or main face 2c and the lateral extension 2d.
Moreover, there may also be a second wall or main face, for example lower 2f in use. Alternatively, the first half-shell 2 may be open, for example lower in use. The second wall or main face 2f effectively closes the half-shell 2.
If provided, the second main wall 2f may be removably or non-removably constrained, for example by glue, snap-on engagement or other similar means to the other walls of the second half-shell 2, or to the walls of the lateral extension 2d, if desired. In this regard, tabs 2fl can be provided to engage respective grooves 2q in the walls of the lateral extension 2d or vice versa.
If desired, the first forming surface 2a is defined substantially centrally or in an intermediate position to the first main face 2c.
In this respect, the first forming surface 2a may comprise a first base 2e, in recess with respect to the upper wall or face 2c and/or the first peripheral edge 2b, and a first section of side wall or surface 2g. The first portion of the side wall or surface 2g extends from the perimeter of the first base 2e to the first peripheral edge 2b. The first section of the side wall or surface 2g is perpendicular or defines a tapered section approaching or receding from the first base 2e. The first perimeter edge 2b can then be raised or staggered with respect to the first base 2e and/or the first wall or upper main face 2c.
In general, at least one of the first perimeter edge 2b and the second perimeter edge 3b is raised respectively with respect to the wall or face of the first half-shell or lower body 2 or second half-shell 3.
Naturally, together with the first base 2e, the side section 2g also contributes to the shape of the spacer device TS resulting from forming in the mold 1. Thus, the first base 2e and the side section 2g will be conformed correspondingly, albeit negatively, to at least the lower face TS1 and to at least part of the thickness TS3 of the tibial plate TS5.
Furthermore, at the first base 2e, positioned substantially centrally, a fluid communication opening CO may be provided between the zone defined by the first forming surface 2a and the possible secondary cavity C2 for the stem TS4 of the spacer device TS in question.
The first base 2e may have a series of (first) ribs 2n adapted to determine the formation of respective (first) longitudinal grooves TS6 of the lower face TS1 of the tibial plate TS5.
A first raised or projecting wall portion 2h, for example annular, may then be provided between a first intermediate portion of the wall or upper face 2c and the first peripheral edge 2b. The section of raised wall 2h can be substantially inclined or perpendicular with respect to the peripheral area of the upper face 2c and, in at least one version of the invention, is tapered when approaching the first peripheral edge 2b.
Preferably, in at least one version of the invention, the remaining part 2m of the first wall or main face 2c surrounding the first forming surface 2a, as well as, if present, the first peripheral edge 2b, the first base 2e and the raised wall section 2h, is flat and substantially coplanar.
In substantially the same manner, the second half-shell, if desired in use, an upper body 3, comprises at least one respective first wall or main face, for example lower 3c in use, wherein the second forming surface 3a and a lateral extension 3d comprising one or more side walls or faces, preferably extending from an outer edge of the main face 3c, are defined or delimited, for example in a substantially central position. There can also be a second wall or main face, for example upper in use. Alternatively, the second half-shell 3 may be open at the top and thus be tub-shaped.
If desired, the second half-shell 3 is therefore an empty body with internal stiffening walls 3s.
The second forming surface 3a may comprise a second base 3e. In one version of the invention and/or in at least some areas thereof, the second base 3e is staggered relative to a lateral portion of the lower face or wall 3c.
The second half-shell 3 also comprises a second section of wall or side surface 3g. The second section of wall or lateral surface 3g extends along the perimeter of the second base 3e, from the latter to the second peripheral edge 3b. The second section of wall or side surface 3g is perpendicular or defines a tapered section approaching or receding from the second base 3e. The second perimeter edge 3b may then be raised or staggered relative to the second base 3e and/or generally to the first top wall or main face 3c.
Naturally, together with the second base 3e, the side surface 3g also contributes to the shape of the spacer device TS resulting from its forming in the mold 1. Therefore, the second base 3e and the side section 3g will be shaped correspondingly, albeit negatively, to at least the upper face TS2 and part of the thickness or part of the third portion or side face TS3 of the tibial plate TS.
In particular, the second base 3e can have a substantially smooth surface, although, in at least one version of the invention, comprising a central longitudinal recess 3n to obtain a rectangular base protrusion TS7 present at the upper face TS2 of the tibial plate TS4.
A second raised or projecting wall section 3h may then be provided between a first intermediate portion of the wall or upper face 3c and the second peripheral edge 3b. The section of raised wall 3h can be substantially inclined or perpendicular with respect to the peripheral area of the wall or lower face 3c and, in at least one version of the invention, it is tapered on approaching the second peripheral edge 3b.
Preferably, in at least one version of the invention, the remaining part 3m of the first wall or main face 3a surrounding the second forming surface 3a, as well as, if present, the second peripheral edge 3b, the second base 3e and the raised wall section 3h, is flat and substantially coplanar.
The handle 8, if present, can be removably or non-removably constrained at the front or rear area in use of one of the half-shells, for example of the second half-shell 3.
Furthermore, at the lateral extension 2d or 3d of at least one of the two half-shells, removable constraining means 10 may be provided for the removable constraint of the two half-shells 2, 3.
With reference to the non-limiting exemplary embodiment illustrated in the Figures, the removable constraining means 10 comprise coupling means, for example snap-on, and possibly a trigger element 11.
More particularly, the removable coupling means 10 may comprise, for example, a tooth or protrusion element 12, integral or in one piece with one of the half-shells 2, 3, or rather, with a trigger element 11, itself integral or in one piece with one of the half-shells 2, 3, capable of engaging in a removable way in a suitable engagement seat 13 delimited in the other half-shell 3, 2 when the mold is in the closed position.
Naturally, it is also possible for the coupling means, if provided, to be placed in a different position than that indicated above or to be of a different structure.
In this regard, when the operator in charge of forming the spacer device closes the mold 1, bringing the first half-shell 2 and the second half-shell 3 into abutment against each other so as to form the cavity C1 between the first forming surface 2a and the first perimeter edge 2b and the second forming surface 3a and the second perimeter edge 3a, he/she can do so using the handle 8. By applying a force, for example a manual force, on the handle 8, he/she can couple the tooth or protrusion element 12, for example inside the engagement seat 13.
Once the forming phase has been completed, and therefore after having waited a predetermined time for the hardening of the material that constitutes the spacer device, the operator acts on the trigger element 11 to determine the release and/or uncoupling of the tooth or protrusion element 12 from the engagement seat 13. If the trigger element 11 is in the vicinity of the handle 8, the operator can, in substantially one-step, grip the handle 8, release the coupling means 10 using the trigger 11 and move the second half-shell 3 away from the first half-shell 2 and, by angularly moving or roto-translating one half-shell 2 in relation to the other 3, if desired by means of the handle 8, cause the mold 1 to open.
Advantageously, the two half-shells 2, 3 are hinged or can be hinged to each other. In this regard, there are hinged or reciprocal displacement means with constraint 14, for example at the rear area in use of the first half-shell 2 and/or the second half-shell 3. These hinged or reciprocal displacement means with constraint 14 allow the rotation or angular displacement (around a special fulcrum or centre of rotation, if desired) or reciprocal roto-translation of the second half-shell 3 with respect to the first half-shell 2, bringing them into abutment with each other and thus causing the mold 1 to close.
Conversely, such hinged or reciprocal displacement means with constraint 14 also make possible the rotation or roto-translation of the release between the first 2 and second 3 half-shells, resulting in the opening of the mold 1. In this phase, the first forming surface 2a and the second forming surface 3a obviously move away from each other while in the mold closing phase they approach each other, until the cavity C1 and, possibly, the secondary cavity C2 are determined.
As a result of the presence of the hinged or reciprocal displacement means with constraint 14, it is possible to ensure perfect coupling between the first peripheral or perimeter edge 2b of the first half-shell 2 and the second peripheral edge 3b of the second half-shell 3.
In this respect, the first perimeter edge 2b and the second perimeter edge 3b abut against each other when the mold is closed, guaranteeing a substantially sealed closure and maintaining a complete contact and/or a complete adherence with each other along their entire extension. Thus, the first perimeter edge 2b is in abutment against and/or matches and/or corresponds to the second perimeter edge 3b. In this way, the spacer device resulting from the forming phase does not require further finishing or cutting phases of the molding burr. The peripheral edges 2b and/or 3b can also act like a knife that cuts the molding burr directly during the forming phase.
In one version of the invention, the two edges have flat abutment surfaces that come into direct contact with each other. These abutment surfaces may be substantially parallel to the support plane of the mold 1 or both have the same inclination, outward or inward, with respect to the cavity C1.
In an alternative version, there are no hinged or reciprocal displacement means with constraint 14, and first half-shell 2 and second half-shell 3 are moved away from and/or brought closer to each other according to other methods known in the field.
Regarding the detail of the extractor component 4 referred to in the exemplary embodiment in the Figures, it can include a base portion 4a, discoidal or of another shape, if desired, and a stem portion 4b, of lower section to the base portion 4a and emerging from the latter, said stem portion 4b having a free tip or end 4c. The base portion 4a is opposite the free tip or end 4c.
If desired, in the resting position the free tip or end 4c protrudes in use in the main cavity C1 or, if provided, secondary cavity C2, and therefore occupies a small part of the space intended for forming the stem TS4. Accordingly, and if desired, a small cavity or recess, created precisely by such tip or end 4c protruding into the cavity C1 or C2 in the rest position, may be provided in the distal end of the stem TS4 of the spacer device TS at the end of the molding method.
Clearly, the tip or end 4c may not protrude into the secondary cavity C2 in the rest condition of the extractor component 4, so that there would be no cavities or recesses in the spacer device TS determined by the tip 4c of the extractor component 4.
The stem 4b may then have a substantially rod or pin-like conformation extending from the base portion 4a and ending with the free tip or end 4c.
Advantageously, the half-shell 2, 3 in which the extractor component 4 is at least partially housed has, at the respective first 2a or second 3a forming surface, a through hole 2p provided at the bottom of the secondary cavity C2 or the cavity C1 and intended to allow the extractor component 4, or rather the respective tip 4c, to pass or to advance towards the respective surface 2a, 3a when the base portion 4a is pressed to extract the spacer device 4.
Preferably, the extractor component 4 is in one piece.
If desired, the base portion 4b is mounted at an opening or housing area 5a (which constitutes a part of the seat 5) in the second main face or wall, for example lower 2f in use of the first half-shell 2, possibly flush with the latter, at least in the rest position of the extractor component 4. In this respect, a sleeve section 2s emerging from the second face or main wall 2f may be provided, which sleeve 2s may delimit a through channel for insertion and housing of the base portion 4a of the extractor component 4.
Conversely, the free tip or end 4c is positioned at the main cavity C1 or secondary cavity C2, in particular at the area of said secondary cavity C2 distal from the respective forming surface 2a. In a version in which the secondary cavity C2 is not present, the tip or end 4c may or may not protrude into the cavity C1 at least in the extraction position, but, if desired, can protrude slightly when the extractor component 4 is in the rest position.
As already partly indicated, the first half-shell 2 can delimit a housing area 5a for the base portion 4a, at an intermediate or central ring-shaped section 2s of the second main wall 2f, if desired, the cross-section of which corresponds to the cross-sectional conformation (e.g., circular) of the base portion 4a and the height of which preferably corresponds at least to the stroke of the extractor component 4 in the transition from the rest position to an extracting position.
In use, according to the non-limiting exemplary embodiment illustrated in the Figures, the operator in charge of forming the spacer device, once the latter is formed, after the mold 1 is opened, will press or act, for example manually, on the base portion 4a, so that the tip or end 4c presses against the stem TS4 or against the lower face TS1 of the tibial plate TS and determines the exit of the formed spacer device TS from the mold 1 and/or its movement away from the forming surface 2a of the first half-shell 2.
Clearly, in the transition from the rest position to the extraction position the extractor component 4 and, more particularly, the respective free tip or end 4c, is inserted completely into the main cavity C1 or, if present, secondary cavity C2, so as to push the spacer device TS out of said cavity or cavities C1, C2 or through the forming surface 2a, 3a and then extract or detach the spacer device TS from the mold 1 in which it has been formed or from a respective half-shell 2, 3.
If desired, the engagement means 6 of the extractor component 4 comprise a series of protrusions or lateral teeth shaped, for example, like a dovetail and extending externally with respect to the stem 4b.
The extractor component 4 can be made, in whole or in part, of a deformable material, which allows the passage of the tip or end 4c through the special hole 2p present at the bottom of the secondary cavity C2 or of the main cavity C1 when the base portion 4a is pressed to extract the spacer device 4, but do not allow it to escape or return to its backward resting position.
In this way, part of the stem 4b remains within the secondary cavity C2 or main cavity C1, effectively preventing a second or subsequent use of the mold 1.
If desired, the second forming surface 3a of the second half-shell 3 has no undercuts. Thus, once molded, the spacer device will remain constrained (albeit temporarily) only to the first forming surface 2a of the first half-shell 2 and to the cavity C1. In this way, it is easier to remove the spacer device formed by the first half-shell 2, for example using the extractor component 4.
Alternatively, if the second forming surface 3a also has undercuts and/or cavities, special extraction means (not illustrated) could also be provided from the second undercut, or application of detaching means could be contemplated, at least on the second forming surface 3a (or possibly also on the first forming surface 2a), such as to facilitate the detachment of the spacer device after its formation.
Of course, the extractor component 4 could be provided also or only in the second half-shell 3.
Abutment blocks 18 may be present at the sides of the mold 1 and at the first wall or main face 2c, the first half-shell 2 and/or the second half-shell 3. Such blocks 18 are placed, for example, at the corners of the walls and/or faces of the half-shells 2, 3, for example at the top, bottom or sides thereof.
These blocks 18 may have complementary shapes or surfaces between blocks present at the first half-shell 2 and blocks present in the second half-shell 3 or between blocks present at the first half-shell 2 or relative housings present at the second half-shell 3 or vice-versa, so as to facilitate closure of the mold 1 and maintenance of the correct forming space when the second half-shell 3 is closed onto the first half-shell 2, or vice-versa.
Such blocks 18 may protrude or be recessed in a wall or face of the half-shells.
If desired, when the mold is closed the blocks 18 can determine the realisation of a space between the first face or wall 2c of the first half-shell 2 and the face or wall, possibly the upper face or wall 3c of the second half-shell 3, or better, between the respective parts 2m and 3m, in which the material that will constitute the spacer device can possibly flow if present in excess with respect to the quantity necessary to obtain the device itself. As a result of the presence of the first peripheral edge 2b and the second peripheral edge 3b, any excess and leaking material will be eliminated (cut) when the same edges are brought into contact with each other and the two half-shells 2, 3 are brought into abutment and tightened together, for example by means of the removable constraining structure 10.
The height of the blocks 18 facilitates perfect contact between the first peripheral edge 2b and the second perimeter edge 3b when the mold 1 is in the closed configuration.
In the mold 1, the first perimeter edge 2b and the second perimeter edge 3b constitute, respectively, the access openings for the first half-shell 2 and the second half-shell 3. The material making up the spacer device TS can be introduced through such access openings, or at least through the access opening determined by the first perimeter edge 2b of the first half-shell 2.
As a result of the mold according to the present invention, the material making up the spacer device TS can have a very high viscosity. In fact, the forces involved in the mold 1 closing step, as well as the specific conformation thereof, also facilitate compression of a very dense and/or viscous material, ensuring that the same flows over the entire area consisting of the cavity C1 and the secondary cavity C2, without leaving empty spaces, and obtaining a fully formed spacer device TS.
Moreover, as a result of the conformation of the mold 1, active pressure is created which compresses and deforms the material constituting the spacer device, causing it to flow into all the areas of the cavity C1 and/or the secondary cavity C2, so as to obtain a perfect filling of the latter by the material in question, with consequent optimal forming of the spacer device in all its parts.
The material constituting the spacer device is supplied to the mold by casting and/or placement on the first forming surface 2a and/or the second forming surface 3a, but, as mentioned, not by injection into the mold 1.
In particular, in at least one version of the invention, the above material is positioned at the first forming surface 2a. In an alternative version, the material may be positioned at the second forming surface 3a or on both the first forming surface 2a and the second forming surface 3a.
With regard to
Elements identical to the previous embodiment will be indicated with the same reference number increased by one hundred units.
Unless otherwise expressly indicated, the features and elements described for the previous exemplary embodiment may be present and provide the same results also for the mold 100, to which reference will now be made.
The mold 100 is very similar to the mold 1 for obtaining the tibial knee spacer device. What changes most are the forming surfaces, which in the mold 100 are dedicated to obtaining the femoral knee spacer device FS.
The mold 100 thus comprises a first half-shell, lower 102 in use, if desired, comprising a first forming surface 102a, and a second half-shell, upper 103 in use, if desired, comprising a second forming surface 103a, and a cavity C1 defined between the first half-shell 102 and a second half-shell 103 (or rather, by their forming surfaces 102a and 103a), when the latter are coupled together and in the closed position.
The first forming surface 102a is delimited by a first perimeter edge 102b, while the second forming surface 103a is delimited by a second perimeter edge 103b. The first peripheral edge 102a is adapted to be brought into abutment against the second peripheral edge 103b, as disclosed for the first embodiment.
With particular reference to the Figures indicated, the first forming surface 102a is adapted to form the upper face FS2 of the femoral knee spacer device FS, while the second forming surface 103a is adapted to form the lower face FS1 of the spacer device FS.
The lower face FS1 is adapted to be articulated with the tibial knee spacer device (for example, the one illustrated in
Advantageously, both the first forming surface 102a and the second forming surface 103a have a curved profile. In particular, the first forming surface 102a has a convex pattern, while the second 103a has a concave pattern.
The cavity C1 substantially determines the formation of the femoral component of the knee spacer device that has a substantially rectangular or oval or C-shaped conformation in the plan view, and a thickness given by the distance between the upper face FS2 and the lower face FS1 of the spacer device FS.
A handle 108, possibly removable, is present at the second half-shell 103, completely similar to the handle 8 disclosed for the first embodiment.
The first half-shell 102 and the second half-shell 103 substantially have a solid or empty block conformation or a box-like or tub-shaped conformation.
The first half-shell 102 therefore comprises at least one wall or main face, for example upper 102c in use, in which the first forming surface 102a and a lateral extension 102d consisting of one or more wall or side faces are defined or delimited, while a second wall or face, for example lower 102f, may or may not be present.
The first forming surface 102a consists of a first base 102e that is convex with respect to the upper face 102c, and a first section of wall or side surface 102g. The first side wall or surface portion 102g extends from the perimeter of the first base 102e to the first perimeter edge 102b. The first perimeter edge 102b is therefore raised with respect to the base 102e and/or the upper face 102c. The first perimeter edge 102b can then be raised or staggered with respect to the first base 102e and/or the first wall or upper main face 102c.
In particular, the base 102e may have a series of ribs 102n adapted to determine the formation of respective longitudinal grooves FS5 of the upper face FS2 of the body of the femoral spacer FS.
A first raised or projecting wall portion 102h may then be provided between a first intermediate portion of the wall or top face 102c and the first peripheral edge 102b. The raised wall section 102h can be substantially inclined or perpendicular to the peripheral area of the upper face 102c and, in at least one version of the invention, is tapered in proximity to the first peripheral edge 102b.
In a substantially similar manner, the second half-shell or upper body 103 can comprise at least one first wall or main face, for example lower 103c in use, in which the second forming surface 103a and a lateral extension 103d consisting of one or more walls or side faces is defined or delimited, for example in a substantially central position.
The second forming surface 103a consists of a base 103e which is concave with respect to the upper wall or face 103c. In one version, the second base 103e rises from the lower wall 103c and the second perimeter edge 103b is therefore raised with respect to the lower face 103c.
In particular, the second base 103e may have a substantially smooth surface, although, in at least one version of the invention, it comprises a longitudinal central rib 103p corresponding to a rectangular base recess FS6 present at the lower face FS1 of the femoral spacer device FS.
The first main face 103c is connected to the second peripheral edge 103b by a raised surface 103h, substantially inclined or inclined or perpendicular to the peripheral area of the upper face 103c and, in at least one version of the invention, is tapered on approaching the first peripheral edge 103b.
With regard to the handle 108, if present it can be provided and constrained at the front or rear area in use of one of the half-shells, for example the second half-shell 3.
Furthermore, at the lateral extension 102d or 103d of at least one of the two half-shells, removable constraining means 111 may be provided for the removable constraint of the two half-shells 102, 103, for example as disclosed with reference to the embodiment of
Advantageously, the two half-shells 102, 103 are hinged or can be hinged to each other. In this regard, hinged or displacement means with constraint 114, for example, are present at the rear area in use of the first half-shell 102 and/or the second half-shell 103.
In addition, in at least one version of the invention the mold 100 can also comprise an extractor component 104.
The extractor component 104 may include a base portion 104a and a stem portion 104b with a free end or tip 104c. The base portion 104a is opposite the free tip or end 104c.
The base portion 104a is mounted at an opening in the second main face or wall, for example lower in use of the second main face 102c of the first half-shell 102, possibly flush with the latter. Conversely, the free tip or end 104c is positioned at the cavity C1, in particular at a central area thereof, for example. The tip or end 104c presses against the upper surface FS2 of the femoral spacer device FS through a special hole 102p present at the cavity C1 and/or at the first forming surface 102a, and causes the ejection of the spacer device formed by the mold 100 and/or the cavity C1 of the first half-shell 102.
In this case, the base portion 104b is mounted at an opening or housing area 105a in the second face or main wall, for example lower 102f in use of the first half-shell 102, possibly flush with the latter, at least in the rest position of the extractor component 104. In this respect, a sleeve section 102s emerging from the second face or main wall 102f may be provided, which sleeve 102s may delimit a through channel for insertion and housing of the base portion 104a of the extractor component 104.
A tubular guide portion 102t that extends from the first wall or main face 102c in the direction of the second wall or face 102f can also be provided to guide the stem portion 104b, the tubular guide section 102t of which flows into the hole 102p.
If desired, the engagement means 106 of the extractor component 104 comprise a series of lateral protrusions extending externally with respect to the stem 104b, shaped, for example, like a dovetail, the disclosure of which has been made for the exemplary embodiment of
Again, the mold 100 may comprise abutment blocks 118 similar to those of the example of
Referring now to
If desired, the extractor component 204 has a base portion 204a and a stem portion 204b, which is, if desired, tubular, with a section that is, for example, polygonal (regular or not) or circular, emerging from the base portion 204 and prepared, directly or not, to engage a spacer device TS, or a part thereof, formed in the mold.
In such cases, the thread or thread portions 206 are formed on, or extend externally from, the stem portion 204b.
According to this variant, the extractor component 204 can also be provided with means adapted to prevent, or in any event signal, the possible unscrewing or uncoupling from the respective half-shell 202, 203.
More particularly, if desired the extractor component 204 can have a support portion 215, e.g., a plate or disc portion from which the stem portion 204b extends and is interposed between the base portion 204a and the latter.
One, two or more teeth or wings 216 can extend from the plate or discoidal portion 215, if desired with a base end or constraint to the support portion 215, as well as a free end, which teeth or wings are substantially bent or curved so as not to extend parallel to the axis of the stem portion 204b, and so as to bring the respective free end close to, or cause it to be bent closer to, a section of the support portion 215 angularly staggered with respect to the constraint or connection of the respective base end.
If multiple wings 216 are provided, for example two, three or more, they may be equally angularly staggered (or not) and are preferably all bent in the same direction, e.g., all with the free end staggered angularly in a clockwise direction (considering the rotation about the axis of the stem portion 204b) in relation to the respective base end or vice versa.
Clearly, the teeth or wings 216 extend from the face of the base portion 215 facing the tip of the stem portion 204b.
On the other hand, the half-shell 202, 203 has at, or rather, on, the defining edge of the mouth or the end for the insertion of the extractor component 203 into the respective seat 205, one or more projections 217, for example two or more, angularly staggered between each other, if desired.
As a result of this precaution, once the extractor component 204 is engaged or inserted into the seat 205, the wing or wings 216 will, during screwing or rotation (counter-clockwise according to the non-limiting exemplary embodiment in the Figures), repeatedly engage with the projection or projections 217 and, as the wings 216 are bent, the rotation necessary for screwing the first 206 and second 207 engagement means for the advancement of the extractor component 204 into the seat 205 will not cause the wings 216 to break, since the projections 217 will engage the wing or wings on the side of their “convexity”, hence on their side facing the tip of the stem portion 204b.
In the event that, at the end of the molding and after extraction of the molded piece, a rotation is commanded in the opposite direction (clockwise according to the non-limiting exemplary embodiment in the Figures) of the extractor component 204, so as to unscrew the first 206 and second 207 engagement means, this would result in the breaking of the wing(s) 216 by the one or more projections 217 which would engage the wing(s) on the side of their “concavity” and then on the side facing away from the tip of the stem portion 204b.
Such measures would in fact ensure that the mold is used only once and that it is therefore disposable, thus meeting the above-mentioned requirements in this respect, since on attempting to remove the extractor component 204 for subsequent use, the broken fin(s) 216 would show that the mold has already been used and cannot (or rather must not) be reused.
Clearly, other arrangements may also be put in place to reveal a possible extraction of the extractor component 204 for an attempt at reuse.
According to the non-limiting exemplary embodiment illustrated in the Figures, the extractor component 204 also comprises a plug component 218 mounted onto the tip of the stem portion 204b. This can, be achieved, for example, by making the stem portion 204b hollow, at least at the respective tip, and by inserting into the latter a shank, or the like, of the plug component 218, then obtaining an engagement between these elements 204b, 218 which can, if desired, be removable, in any suitable manner, for example a snap-on, bayonet, interlocking or similar engagement.
In this respect, the plug component 218 would be the one that would actually grasp the molding cavity C1 and engage the TS spacer, or a part thereof, to determine its removal once molded.
In such cases, the plug component 218 could be made of the same material as the respective half-shell 202, 203, while the other elements of the extractor component 204, such as the base portion 204a and the stem portion 204b, could be made (in one piece with each other) of a different, for example more resistant, material.
Thus, for example, if the mold is made of polypropylene or other primary material, the base portion 204a and the stem portion 204b could be made of glass fibre-filled nylon or another suitable secondary material which is more rigid than polypropylene or the primary material and which, however, cannot or should not be brought into contact with the spacer TS material.
As will be appreciated, with a mold according to the present invention it is possible to implement a method for extracting a spacer device, or a part thereof, from a mold 1, 100.
According to this method, after a spacer device TS or FS, or a part thereof, has been molded, the mold is opened by moving away the first half-shell 2, 102, 202 and the second half-shell 3, 103, 203, so that the spacer device TS or FS, or a part thereof, remains in contact with one of the half-shells 2, 3, 102, 103, 202, 203, or better, with a single forming surface 2a, 3a, 102a, 103a.
At this point, the extractor component 4, 104, 204 is activated so as to move the spacer device TS or FS away from the half-mold 2, 3, 102, 103, 202, 203 with which it is in contact, or better, from a respective forming surface 2a, 3a, 102a, 103a.
Advantageously, when the extractor component 4, 104, 204 is activated it is moved between a rest position and an extraction position, in which the extractor component 4, 104, 204 protrudes within a molding cavity C1, C2 or through a forming surface 2a, 3a, 102a, 103a to a greater extent than the rest position. Preferably, the extractor component 4, 104, 204 is operated manually by pressing against or acting on a base portion 4a, 104a, 204a thereof, starting from a wall or zone of the respective half-shell 2, 3, 102, 103, 202, 203 which is opposite that of delimitation of the forming surface 2a, 3a, 102a, 103a, if desired. Moreover, if engagement means 6, 7, 106, 107 are provided, then, once the extractor component 4, 104, 204 is actuated, the first engagement means 6, 106, 206 engage the second engagement means 7, 107, 207. In such cases, the engagement between the first 6, 106 and second 7, 107 engagement means may prevent or limit the return to the rest position of the extractor component 4, 104.
As will be appreciated, a mold according to the present invention allows easy and quick extraction of a spacer device formed therein.
Moreover, if engagement means are provided they ensure that the mold is used only once and that it is therefore disposable, thus meeting the needs indicated above in relation to this feature.
Modifications and variants of the invention are possible within the scope of protection defined by the claims.
| Number | Date | Country | Kind |
|---|---|---|---|
| 102021000009905 | Apr 2021 | IT | national |
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/IB2022/053585 | 4/16/2022 | WO |
