The present invention concerns a prosthetic device for temporomandibular joint and a corresponding prosthetic assembly comprising said prosthetic device and a guide device for the preparation of a suitable bone seating.
The prosthetic device as above is particularly suitable for applications in patients with non-extensive joint pathologies, for example in the case of osteoarthrosis/osteoarthritis, condylar resorption, benign neoplasms, or in the case where previous surgeries have failed.
This solution can also be adopted as a first surgery in a large number of patients, where the traditional path would involve other attempts at functional arthroplasty, normally destined to fail.
It is known that the reconstruction of the temporomandibular joint is a problem due to the complex role it plays inside the stomatognathic system.
It plays an essential role in chewing, in speech, in supporting respiratory exchanges and in swallowing, and is a secondary growth center for the jaw during pre-puberty. Furthermore, the temporomandibular joint is subjected to repeated loading/unloading cycles more than any other joint in the body.
Given the complexity of the anatomy and biomechanics of said joint, surgery to solve problems and related pathologies is complex and currently very invasive.
The temporomandibular joint articulates the mandibular bone with the temporal bone, in particular it connects the mandibular condyle with the glenoid fossa of the temporal bone.
Prosthetic devices for the temporomandibular joint therefore comprise two components: a condyle prosthesis and a glenoid fossa prosthesis respectively associated, during use, with the mandibular condyle and the glenoid fossa of the temporal bone. Both components are made according to the specific needs of the patient and his/her anatomical morphology.
Before they are applied, it is necessary to perform osteotomies to prepare the condyle and the glenoid fossa to accommodate the respective prostheses. For this purpose, guide devices can be provided able to facilitate the operation of bone resection performed by the surgeon. Furthermore, it is necessary to use traditional surgical burrs that cause damage, even very extensive, to the affected bone tissues and those surrounding them.
The prosthetic devices currently used are very bulky and require a very large installation space between the mandibular branch and the base of the skull, which is necessary to be able to insert the fossa prosthesis and the condyle prosthesis. Because of this, often the osteotomy of the condyle, and if necessary also of the glenoid fossa, must necessarily be very large and invasive.
This limits the indications for the implantation of the joint prosthesis only to very severe cases.
The sizes of current prostheses also make the surgical procedure very invasive, which provides a pre-auricular incision, for the insertion of the glenoid fossa prosthesis, and a retro-submandibular incision, for the insertion of the branch/condyle prosthesis.
The invasiveness of current prostheses and the surgical procedure for their installation lead to long hospitalization times and possible complications for the patient.
There is therefore a need to perfect a prosthetic device for application to the temporomandibular joint and corresponding prosthetic assembly that can overcome at least one of the disadvantages of the state of the art.
In particular, one purpose of the present invention is to provide a prosthetic device for temporomandibular joint the implantation of which requires a limited osteotomy of the condyle and possibly of the glenoid fossa.
Another purpose of the present invention is to provide a prosthetic device for temporomandibular joint that allows to extend the surgical indications, and therefore applicability, to a greater number of patients compared with the use of traditional prostheses.
Another purpose of the present invention is to provide a prosthetic device for temporomandibular joint that consists of a limited number of components so as to simplify and speed up its installation.
Another purpose of the present invention is to provide a prosthetic assembly for temporomandibular joint that is advantageously customized/individualized and patient-specific, and that allows to simplify and at the same time make the corresponding surgical technique less invasive.
The Applicant has devised, tested and embodied the present invention to overcome the shortcomings of the state of the art and to obtain these and other purposes and advantages.
The present invention is set forth and characterized in the independent claims. The dependent claims describe other characteristics of the present invention or variants to the main inventive idea.
In accordance with the above purposes, a prosthetic device for temporomandibular joint, which overcomes the limits of the state of the art and eliminates the defects present therein, comprises a first prosthetic component, able to be associated with a mandibular condyle of a patient, and a coordinated second prosthetic component, able to be associated with a respective glenoid fossa of the patient.
The first prosthetic component is configured to cooperate with the second prosthetic component to define the temporomandibular joint and comprises a convex portion, configured to cooperate with the second prosthetic component to define the temporomandibular j oint.
According to one aspect of the present invention, the first prosthetic component comprises at least one anchoring element projecting from, and attached at least to, the concave portion as above, since the anchoring element is contained in the concave portion and has a main extension along a latero-medial axis. The anchoring element is configured to be inserted into a mating anchoring seating present, or provided, on the mandibular condyle as above. Furthermore, the coupling seating is at least partly open along the latero-medial axis.
In this way, the first prosthetic component can be easily inserted in a direction parallel to the latero-medial axis as above, allowing to limit the removal of bone material from the patient to a minimum, and at the same time allows to greatly simplify the surgical practice. In addition, the minimal invasiveness of the surgical approach and of the resection of the condyle allows to extend the surgical indications and therefore a considerably greater applicability compared with the use of traditional prostheses.
In some embodiments, the first prosthetic component comprises a concave portion, defining a coupling seating having a shape mating with the shape of the mandibular condyle. The concave portion is therefore configured to cooperate with the second prosthetic component to define the temporomandibular joint. The convex portion as above is opposite the concave portion.
In accordance with some embodiments, a guide device is provided to prepare an anchoring seating for the prosthetic device as above, in particular to position the first prosthetic component.
The guide device comprises a central body able to be positioned against at least the upper lateral part of a mandibular condylar branch, and a guide wall associated at the upper part with the central body and having the profile of the osteotomy to be performed on the condyle.
According to a characteristic aspect of the present invention, the guide device has a groove which extends vertically from the guide wall toward the central body. Furthermore, the groove is open at the upper part and is through in a direction parallel to the latero-medial axis.
Some embodiments of the present invention comprise a prosthetic assembly, advantageously customized and patient-specific, provided with the prosthetic device and the corresponding guide device as above.
These and other aspects, characteristics and advantages of the present invention will become apparent from the following description of some embodiments, given as a non-restrictive example with reference to the attached drawings wherein:
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To facilitate comprehension, the same reference numbers have been used, where possible, to identify identical common elements in the drawings. It is understood that elements and characteristics of one embodiment can conveniently be incorporated into other embodiments without further clarifications.
We will now refer in detail to the possible embodiments of the invention, of which one or more examples are shown in the attached drawings. Each example is supplied by way of illustration of the invention and shall not be understood as a limitation thereof. For example, one or more characteristics shown or described insomuch as they are part of one embodiment can be varied or adopted on, or in association with, other embodiments to produce another embodiment. It is understood that the present invention shall include all such modifications and variants.
Before describing these embodiments, we must also clarify that the present description is not limited in its application to details of the construction and disposition of the components as described in the following description using the attached drawings. The present description can provide other embodiments and can be obtained or executed in various other ways. We must also clarify that the phraseology and terminology used here is for the purposes of description only, and cannot be considered as limitative.
Some embodiments described here concern a prosthetic device 10 for temporomandibular joint (
Here and hereafter, the terms proximal, distal, anterior, posterior, medial, lateral are defined by their standard use for a person of skill in the art to indicate a particular aspect or orientation of a bone, an anatomical part, a prosthetic device and its components, or other elements according to the relative disposition of the natural anatomy of the human and/or animal body, or directional terms of reference with respect thereto.
With particular reference to
The prosthetic device 10 therefore comprises a first prosthetic component 11, able to be associated with a condyle 112 of a patient, and a coordinated second prosthetic component 12, able to be associated with a respective fossa of the patient. In particular, the condyle 112 is suitably shaped to house the first prosthetic component 11, as will be described in more detail below.
The first prosthetic component 11 comprises a concave portion 13, defining a coupling seating 14 having a shape mating with the shape of the previously shaped condyle 112.
The first component 11 comprises a convex portion 15, opposite the concave portion 13 and configured to couple with the second prosthetic component 12 to define the temporomandibular j oint.
The first prosthetic component 11 is provided with at least one anchoring element 16 projecting from, and attached at least to, the concave portion 13. The anchoring element 16 has an overall size such as to be substantially contained inside the concave portion 13.
The anchoring element 16 has a main extension along a latero-medial axis X. In particular, the term latero-medial here and hereafter is intended to indicate a direction that goes from a lateral zone toward a zone located in the proximity of the median plane of the patient’s body.
The anchoring element 16 is configured to be inserted in a mating anchoring seating 113 (
The coupling seating 14 is at least partly open along the latero-medial axis X so as to allow, in one possible application, the coupling of the first prosthetic component 11 with the condyle 112 in a direction parallel to the latero-medial axis, which runs from the outside to the inside (
The particular geometry of the prosthetic device 10 and in particular of the first prosthetic component 11 provided with the anchoring element 16 with latero-medial insertion allows to limit the removal of bone material from the patient to a minimum, and at the same time allows to greatly simplify the surgical practice which becomes less invasive thanks to the need to only create one access route, with a pre-aural incision.
According to some embodiments described here, with particular reference to
The first prosthetic component 11 can be configured as a condyle prosthesis configured to at least partly cover the condyle 112 of the patient. This first prosthetic component 11 is conceived as a covering prosthesis with the purpose of preserving the original bone portion of the condyle 112 as much as possible. Favorably, this condylar prosthesis can be used in the case of non-extensive pathologies, which in fact are those with the greatest incidence.
In particular, the first prosthetic component 11 is configured to cover the lateral surface of the condyle 112, the upper surface - the one that normally articulates with the fossa - and possibly also the posterior and anterior surfaces. Obviously, given the mode of insertion of the first prosthetic component 11, that is, in a direction parallel to the latero-medial axis X, it is not provided to cover the medial portion of the condyle 112 (
With particular reference to
The upper wall 19 has a shape such as to define, at the bottom, the concave portion 13 and, at the upper part, the convex portion 15 (
The upper wall 19 is configured to at least partly cover the condyle leaving an internal medial part thereof substantially free. For this purpose, the shell 18 is open, as well as at the bottom, also along the latero-medial axis X in a zone opposite the external lateral wall 20 and terminal of the upper wall 19 (
The external lateral wall 20 has a main development along the mandibular branch 114 and is substantially parallel or subparallel to the median plane of the body.
Optionally, the external lateral wall 20 can be provided with at least one through hole 21 for the insertion of an attachment element, for example a screw 22 (see for example
In the embodiment described here, with particular reference to
Although the upper wall 19, the external lateral wall 20 and the anterior 23 and posterior walls 24 have been described as distinct and separate elements, it goes without saying that they can be made in a single body so that one can be an extension of the other, according to the geometry and the reciprocal disposition just described.
According to some embodiments described here, the anchoring element 16 is configured as a lamella 25 attached at the upper part to the upper wall 19, on the side of the concave portion 13, and laterally to the external lateral wall 20. However, it is not excluded that the lamella 25 can be attached only to the upper part 19. The lamella 25 can be conformed as a wall, a septum, a suitably shaped ridge projecting from the upper wall 19.
In particular, the lamella 25 projects in a direction substantially orthogonal to the upper wall 19 (
The lamella 25 has a longitudinal extension, or length, L (
However, it is not excluded that the lamella 25 may also have a shorter length L. Evidently, the greater the length L, the greater the useful surface in contact with the bone of the condyle for a better integration and stabilization.
The lamella 25 has a height H (
The lamella 25 has a thickness W1 (
Advantageously, the lamella 25 is configured to promote the primary stabilization of the prosthesis, the neoformation of cancellous bone and the osseointegration with the cortical bone of the condyle 112.
In particular, the lamella 25 can have a substantially rectangular shape and be provided with macro grooves and micro grooves to promote the neoformation of cancellous bone and the osseointegration with the cortical bone of the condyle 112.
In one embodiment,
The lamella 25 can also be provided with a chamfer 29 able to facilitate the latero-medial insertion of the first prosthetic component 11 in the anchoring seating 113 on the condyle 112. In this case,
According to some embodiments, the first prosthetic component 11 is made with a biocompatible material, for example titanium or an alloy thereof, or other possible known or unknown biocompatible materials. Advantageously, the articulating surface of this first prosthetic component 11 can be treated so that it is as smooth as possible, for example mirror-like, in order to reduce frictions during joint movement to a minimum.
In particular, the lamella 25 can be made of titanium, and its surface can be favorably treated to increase the contact surface with the bone and promote osseointegration with the latter. For example, the surface of the lamella 25 can be treated with a sandblasting process with hydroxyapatite and acid passivation (RBM). In possible embodiments, the lamella 25 can, alternatively and for the purposes of osseointegration, have an at least partly porous or lattice-shaped structure, which for example reproduces the trabecular structure of the bone, possibly associated with a portion of compact material.
The best osseointegration is also promoted by the piezo surgical preparation of the surgical site, which provides a preservation of the bone tissues and much less damage than a traditional cutter for the preparation of an osteotomy site.
In some embodiments, the first prosthetic component 11 can be made with a Selective Laser Melting (SLM) process, or with a Direct Metal Laser Sintering (DMSL) process, or again by means of Electron Beam Melting (EBM) technique, or in general by means of a suitable “additive manufacturing” or 3D printing technique, based on the specific anatomical needs of the patient. Such techniques, for example, are advantageous in the event the first prosthetic component 11, and in particular the lamella 25, at least partly have an at least partly porous or lattice-shaped structure, for example trabecular, possibly associated with a portion of compact material.
According to the embodiment shown in
The second prosthetic component 12 comprises an articulating portion 30 able to cooperate, during use, with the convex portion 15 of the first prosthetic component 11, and a zygomatic portion 31 which, during use, is able to cover the zygomatic arch of the patient.
The articulating portion 30 has a convex articulating surface 32 having a shape mating with the convex portion 15.
The upper part of the articulating portion 30, the one which, during use, is positioned in contact with the glenoid fossa of the patient, has a shape that traces the pre-existing, or surgically shaped, bone surface of the fossa.
The second prosthetic component 12 can be stabilized to the temporal bone by means of screws 34. For this purpose, both the articulating portion, in an outermost part thereof, and also the zygomatic portion 31 can provide through holes 33 for the screws 34. In the example described here, the zygomatic portion 31 is stabilized with three screws 34.
According to some embodiments, the second prosthetic component 12 is made with a biocompatible material, for example ultra-high molecular weight polyethylene (UHMWPE), or other possible known and unknown biocompatible materials.
In accordance with the embodiment described in
The surgical template 35 has a central vertical groove 38 open at the upper part which divides the guide wall 37 into a first guide branch 37a and a second guide branch 37b.
In the example described here, the guide wall 37 has a substantially curved profile, however, it is not excluded that the guide wall 37 may have a squared profile, or other profile suitable to make the least invasive osteotomy possible.
The vertical groove 38 is through in a direction parallel to the latero-medial axis X in order to allow the surgeon to perform a vertical osteotomy in order to prepare the anchoring seating 113 in the condyle 112 of the patient.
The guide groove 38 can also extend, in part, in the central body 36.
The groove 38 is open at the upper part and has a terminal part, or bottom, 39 able to act as an abutment for the surgical blade during the preparation of the anchoring seating 113 (
The groove 38 has a depth D substantially equal to the height H of the lamella 25 of the first prosthetic component 11, and a width W2 smaller than or equal to the thickness W1 of the lamella 25 (
The surgical template 35 is provided with at least one calibrated hole 40 prepared through the central body 36. The calibrated hole 40 allows to prepare a corresponding hole in the condyle 112 of the patient to position a screw which serves to stabilize the surgical template 35 and subsequently to attach the first prosthetic component 11. In possible implementations, the condylar prosthetic component, that is, the condyle 112, can be modeled and shaped in its external lateral part in order to house more attachment screws and, for this purpose, this can also provide the use of a dedicated template.
Operatively, after the identification of the part of the condyle 112 to be removed, the surgical template 35, having profiles suitably shaped according to the anatomical needs of the patient, is positioned on the condylar branch 114 and attached to it with a screw (not shown) (
It is clear that modifications and/or additions of parts may be made to the prosthetic device for temporomandibular joint and corresponding prosthetic assembly as described heretofore, without departing from the field and scope of the present invention as defined by the claims.
It is also clear that, although the present invention has been described with reference to some specific examples, a person of skill in the art shall certainly be able to achieve many other equivalent forms of prosthetic device for temporomandibular joint and corresponding prosthetic assembly, having the characteristics as set forth in the claims and hence all coming within the field of protection defined thereby.
In the following claims, the sole purpose of the references in brackets is to facilitate reading: they must not be considered as restrictive factors with regard to the field of protection claimed in the specific claims.
Number | Date | Country | Kind |
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102020000007201 | Apr 2020 | IT | national |
Filing Document | Filing Date | Country | Kind |
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PCT/IT2021/050089 | 3/30/2021 | WO |