WO2024259475A1

WO2024259475A1 - A temporomandibular joint replacement implant

Info

Publication number: WO2024259475A1
Application number: PCT/AU2024/050631
Authority: WO
Inventors: Stefan Medio; Nathan Wang; George Dimitroulis
Original assignee: Maxoniq Ip Pty Ltd
Current assignee: Maxoniq Ip Pty Ltd
Priority date: 2023-06-19
Filing date: 2024-06-17
Publication date: 2024-12-26
Anticipated expiration: 2025-12-19

Abstract

There is proposed a temporomandibular joint replacement implant comprising, a fossa component, a jaw component, wherein the fossa component defines a metallic articular surface and the jaw component comprises a non-metallic condylar portion engaging the metallic articular surface. The fossa component may be made entirely of metal alloy such as titanium and engages a mobile condylar head covered by a thick UHMWPE liner attached to a jaw component made of metal alloy such as titanium.

Description

A TEMPOROMANDIBULAR JOINT REPLACEMENT IMPLANT

FIELD OF THE INVENTION

The present invention relates generally to an improved type of temporomandibular joint replacement implant.

BACKGROUND OF THE INVENTION

Osteoarthritis of the human temporomandibular joint can result in severe debilitating jaw pain and dysfunction. End stage joint diseases such as osteoarthritis are destructive to all parts of the temporomandibular joint which may require the complete surgical removal of the joint.

Unless the resected temporomandibular joint complex is immediately reconstructed with a prosthetic total joint replacement system, the patient is left with a significant jaw deformity.

Currently used joint replacement systems have a plastic on metal interface consisting of a fixed Ultra-high Molecular Weight Polyethylene (UHMWPE) cup that acts as a functional liner against a mobile metal head made of alloys of Vitallium (Cobalt/Chromium/Molybdenum) or in the case of a temporomandibular joint replacement implant, Titanium (Ti-6AI-4V).

The published prior art includes U.S. Patent 6,132,466 (Hoffman et al) and U.S. Patent 11 ,801 ,145 (Industrial Technology Research Institute), which both disclose various configurations of temporomandibular joint replacement implant systems.

Commonly, existing temporomandibular joint prosthetic systems have metallic condylar heads which articulate against an UHMWPE fossa lining. The fossa component may either be made wholly of UHMWPE or may be a hybrid version of titanium alloy backing fixed to the cranial base with an UHMWPE liner that is connected by various chemical or mechanical fixings.

It should be appreciated that any discussion of the prior art throughout the specification is included solely for the purpose of providing a context for the present invention and should in no way be considered as an admission that such prior art was widely known or formed part of the common general knowledge in the field as it existed before the priority date of the application.

SUMMARY OF THE INVENTION

It is an object of the present invention to provide a temporomandibular joint replacement implant, which will overcome or substantially ameliorate at least some of the deficiencies of the prior art, or at least provide the public with a useful alternative. The foregoing objects should not necessarily be considered as cumulative and various aspects of the invention may fulfil one or more of the above objects.

The invention could be broadly understood to comprise a temporomandibular joint replacement implant comprising a fixable fossa, constructed at least partly from a metallic material, which engages a non-metallic condylar head of a jaw component/ramus portion.

In one aspect of the invention, but not necessarily the broadest or only aspect, there is proposed a temporomandibular joint replacement implant, comprising: a fossa component; a jaw component, wherein: the fossa component defines a metallic articular surface; and the jaw component includes a non-metallic condylar portion engaging the metallic articular surface.

In a preferred form the condylar portion, or a part thereof, is reversibly engageable with the jaw component.

Preferably, the fossa component is constructed substantially from a metallic material, and may be selected from a group including titanium.

The non-metallic condylar portion is preferably constructed from a polymeric material and/or a ceramic material.

In one form the polymeric material comprises an Ultra-high Molecular Weight Polyethylene (UHMWPE).

The jaw component defines a ramus portion which is preferably formed from a metallic material. In one form the condylar portion defines a mediolateral elongate axis in a transverse plane. The condylar portion may be ovular in the transverse plane.

Preferably, the jaw component defines a ramus portion wherein the condylar portion predominantly extends medially with respect to the ramus portion.

The metallic articular surface defines a mediolateral elongate axis in the transverse plane, wherein the fossa component defines a lateral flange in a sagittal plane and wherein the metallic articular surface predominantly extends medially with respect to the lateral flange.

When in the sagittal plane, the metallic articular surface defines a posterior backstop, which may be defined by a posterior wall of substantially uniform thickness.

When in the sagittal plane, the metallic articular surface defines a posterior region and an anterior region and wherein the posterior portion tends to a greater angle with respect to a transverse plane as compared to the anterior portion.

When in the sagittal plane, the articular surface defines a posteriorly located apex.

In one form the jaw component defines a ramus portion, wherein the condylar portion is removeable from the ramus portion.

The ramus portion preferably defines a superior key that fits an inferior socket of the polymeric condylar portion. The key and the socket may be non-rotationally keyed together.

The condylar portion may define an ovular section capped by a domed section.

In one form the key defines longitudinal indentations and wherein the socket defines longitudinal protrusions which key into the longitudinal indentations. The cross-section of the key and socket may therefore be nonsymmetric along a longitudinal axis thereof. The reader should however appreciate that in another form the key and socket may be symmetrical along the longitudinal axis.

The key generally defines a first side screw hole, which may be blind. The condylar portion defines a second side screw hole, which is preferably a through hole.

The condylar portion, in one form, defines an annular interface for the second side screw hole.

The annular interface defines an annular portion such that a head of a screw, being configured to engage the first screw hole and second screw hole, can be countersunk.

In one form, the annular interface comprises a cap which closes over a head of the screw.

The skilled addressee will appreciate that the present temporomandibular joint replacement implant has the articulating bearing components of the prior art essentially reversed, wherein metal forms the fixed articulating surface covering the base of skull (i.e. the fossa component) and the mobile condylar head being composed of polymer bearing material such as UHMWPE, or a ceramic bearing material. As such, the fixed fossa component may be made entirely of metal alloy such as titanium (Ti-6AI-4V) and opposing a mobile condylar head covered by a thick UHMWPE liner attached to a ramus portion unit. The ramus portion being constructed from a metal alloy such as titanium.

The prosthetic fossa component protects the bony skull base of the patient from wear and perforation into the cranial cavity resulting from the constant frictional motion of the prosthetic condylar head. While previous temporomandibular joint prosthetic systems have incorporated UHMWPE into their fossa design, the present temporomandibular joint replacement implant has a fossa of metal alloy.

This new combination of a fixed metal fossa articulating against a mobile plastic condylar head offers several advantages.

First, the thin metal fossa lining the skull base allows for a more natural positioning of the condyle's head, improving the axis of rotation and avoiding jaw deviation during mandible movement. Second, the fossa may have a posterior backing which provides protection to the tympanic plate and middle ear from the functional pressures exerted by the condylar head.

Third, the metal fossa's posterior backing enables the condylar head to be seated in a fixed position, ensuring a stable occlusion and facilitating orthognathic surgical procedures if necessary.

Finally, the UHMWPE cap covering the condylar head can either be permanently fixed or designed as a removable component. The latter option allows for the replacement of the UHMWPE cap, preserving the metallic components of the joint implant during revision surgeries rather than requiring removed each time.

In another aspect of the invention there is proposed a method of temporomandibular joint replacement, including the steps of: providing a temporomandibular joint replacement implant in accordance with any one of the above aspects; preparing the implant site for implantation of the fossa component; attaching the fossa component at the implant site; and engaging the jaw component to the fossa component wherein the non-metallic condylar portion engages the metallic articular surface of the fossa component.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate an implementation of the invention and, together with the description and claims, serve to explain the advantages and principles of the invention.

In the drawings,

Figure 1 is a perspective view of a jaw component of a first embodiment of a temporomandibular joint replacement implant of the present invention;

Figure 2 is a lateral side view of a fossa component of the implant of the present invention;

Figure 3 is a medial side view of the fossa component of Figure 2;

Figure 4 is a posterior view of the fossa component of Figure 2; Figure 5 is a schematic perspective view of a condylar portion of the jaw component of Figure 1 ;

Figure 6 is a perspective view of a key, in accordance with one embodiment, of jaw component of Figure 1 configured for engaging the condylar portion of Figure 5;

Figure 7 is a perspective view of the condylar portion of Figure 5;

Figure 8 is a perspective view of the condylar portion of Figure 7 aligned with the key of Figure 6, for engagement therewith;

Figure 9 is a cross-sectional view of the condylar portion of Figure 1 ;

Figure 10 is an underside view of a second embodiment of the condylar portion;

Figure 11 is a perspective view of the condylar portion of Figure 10;

Figure 12 is a side view of the condylar portion of Figure 10;

Figure 13 is a perspective view of the jaw component of a second embodiment of the temporomandibular joint replacement implant;

Figure 14 is a partial view of the ramus portion of the jaw component of Figure 13, illustrating the key, in accordance with a second embodiment configured for engaging the condylar portion of Figure 10;

Figure 15 is a side view of the ramus portion of the jaw component of a third embodiment; and

Figure 16 is a perspective view of the ramus portion of Figure 15.

DETAILED DESCRIPTION OF THE ILLUSTRATED AND EXEMPLIFIED EMBODIMENTS

Similar reference characters indicate corresponding parts throughout the drawings. Dimensions of certain parts shown in the drawings may have been modified and/or exaggerated for the purposes of clarity or illustration.

Referring to the drawings for a more detailed description, there is illustrated a temporomandibular joint replacement implant, demonstrating by way of examples, arrangements in which the principles of the present invention may be employed.

As illustrated in the figures, the temporomandibular joint replacement implant comprises a fossa component 101 and a jaw component 102. The fossa component 101 is configured to be fixed to the base of the cranium of a patient, and the jaw component 102 attaches to the resected jaw of the patient.

With reference to Figures 1 to 3, the fossa component 101 defines a metallic articular surface 103 and the jaw component 102 comprises a non-metallic condylar portion 104, which articulates against the articular surface 103 of the fossa component 101.

It is envisaged that the fossa component 101 will be constructed entirely from a metallic material, and in one embodiment may be made of a titanium alloy.

The polymeric condylar portion 104 comprises a polymeric material, and in one embodiment comprises Ultra-high Molecular Weight Polyethylene (UHMWPE). Alternatively, the condylar portion 102 may be constructed from a ceramic material.

The jaw component 102 may define a ramus portion 105. The ramus portion 105 may be metallic, and in one embodiment is entirely metallic. As shown in Figure 1 , the ramus portion 105 may be split into an anterior portion 106 and a posterior portion 107 defining a substantially inverted teardrop shaped aperture therebetween. The posterior portion 107 may include a plurality of screw holes 108 for bone screws to engage the ascending ramus of the patient’s jaw.

The condylar portion 104 may define a mediolateral elongate axis 109 in the transverse plane. Figure 9 illustrates one embodiment the condylar portion 104 which is substantially ovular in the transverse plane. Shown in Figure 9 is a lateral end 110 and a medial end 111 of the condylar portion 104. As shown in Figure 1 , the condylar portion 104 may extend predominantly medially with respect to the ramus portion 105.

With reference to Figure 4, the articular surface 103 may similarly define a mediolateral elongate axis 112 in the transverse plane.

The fossa component 101 may define a lateral flange 103 having screw holes 114 therethrough for use in the attachment to the side of the base of the skull. The articular surface 103 may predominantly extend medially with respect to the lateral flange 113. With reference to Figure 2, in the sagittal plane, the articular surface 103 may define a posterior backstop 115. The posterior backstop 115 may be defined by a posterior wall 116. The posterior wall 116 may be of substantial uniform thickness. With reference to Figure 4, the posterior wall 116 may taper inferiorly.

In the sagittal plane, the articular surface 113 may define an anterior region 117 and a posterior region 118 and wherein the posterior region 118 tends to a greater angle with respect to the transverse plane as compared to the anterior region 117.

Furthermore, in the sagittal plane, the articular surface 103 may define a posterior located apex 119.

In one embodiment, the condylar portion 104 is removable from the ramus portion 105. The ramus portion 105 may define a superior key 120 that is configured to engage an inferior socket 121 of the polymeric condylar portion 104. Illustrated in Figure 6, the key 120 may have a smaller cross-section as compared to a crosssection of an adjacent portion 122.

The key 120 and the socket 121 may be non-rotationally keyed. In embodiments, the key 120 defines longitudinal indentations 123 and wherein the socket 121 defines longitudinal protrusions 124 which non-rotatably key into the longitudinal indentations 123.

As is shown in Figure 9, the cross-section of the key 120 and socket 121 may be nonsymmetric along a longitudinal axis so that the condylar portion 104 cannot be accidentally attached in the incorrect orientation.

The condylar portion 104 may comprise an ovular section 128 capped by a domed portion 129. In the sagittal plane, the domed portion may define a radius less than that defined by the articular surface 103.

With reference to Figure 6, the key 120 may define a side screw hole 125. The side screw hole 125 is preferably accessibly located on the lateral side of the key 120. Furthermore, the screw hole 125 in the present embodiment is a blind hole.

The condylar portion 104 may define a side screw hole 126 which may be a through hole so that a fixation screw (not shown) can be inserted through the screw hole 126 of the condylar portion 104 into the screw hole 125 of the key 120 to thereby attach the condylar portion 104 to the key 120.

The condylar portion 104 may define an interface 127 surrounding the side screw hole 126. The interface 127 may define an annular portion so that a head of the screw can be countersunk. The interface 127 may be a cap which closes over the head of the screw.

Figures 10 to 12, illustrate another embodiment of the removable condylar portion 104, which includes an elongate socket 121. The elongate socket 121 is dimensioned to engage the correspondingly shaped key 120 which is formed on the ramus portion 105, as illustrated in Figure 14.

When in position, as illustrated in Figure 13, the screw hole 126 of the removable condylar portion 104 coaxially aligns the screw hole 125 of the key 120, as previously discussed.

As shown in Figures 15 and 16, the ramus portion 105 is generally elongate and includes the anterior portion 106 and the posterior portion 107. In the present embodiment, the ramus portion 105 includes two rows of screw holes 108 for bone screws to engage the ascending ramus of the patient’s jaw.

The skilled addressee will now appreciate the advantages of the illustrated invention over the prior art. In one form, the invention provides a temporomandibular joint replacement implant which allows for a more natural positioning of the condyle's head, improving the axis of rotation and inhibiting jaw deviation during mandible movement. Furthermore, the fossa may have a posterior backing which provides protection to the tympanic plate and middle ear from the functional pressures exerted by the condylar head. The metal fossa's posterior backing also enables the condylar head to be seated in a fixed position, ensuring a stable occlusion and facilitating orthognathic surgical procedures if necessary. Finally, the UHMWPE cap covering the condylar head can either be permanently fixed or designed as a removable component.

Various features of the invention have been particularly shown and described in connection with the exemplified embodiments of the invention, however it must be understood that these particular arrangements merely illustrate the invention and it is not limited thereto. Accordingly, the invention can include various modifications, which fall within the scope of the invention.

In the claims which follow and in the preceding description of the invention, except where the context requires otherwise due to express language or necessary implication, the word "comprise" or variations such as "comprises" or "comprising" is used in an inclusive sense, i.e. to specify the presence of the stated features but not to preclude the presence or addition of further features in various embodiments of the invention.

Claims

1. A temporomandibular joint replacement implant comprising: a fossa component; a jaw component, wherein: the fossa component defines a metallic articular surface; and the jaw component includes a non-metallic condylar portion engaging the metallic articular surface.

2. The temporomandibular joint replacement implant in accordance with claim 1 , wherein the fossa component is constructed substantially from a metallic material, selected from a group including titanium.

3. The temporomandibular joint replacement implant in accordance with claim 1 , wherein the non-metallic condylar portion is constructed from a polymeric material and/or a ceramic material.

4. The temporomandibular joint replacement implant in accordance with claim 3, wherein the polymeric material comprises Ultra-high Molecular Weight Polyethylene (UHMWPE).

5. The temporomandibular joint replacement implant in accordance with claim 1 , wherein the jaw component defines a ramus portion and wherein the ramus portion is metallic.

6. The temporomandibular joint replacement implant in accordance with claim 1 , wherein the condylar portion defines a mediolateral elongate axis in a transverse plane.

7. The temporomandibular joint replacement implant in accordance with claim 6, wherein the condylar portion is ovular in the transverse plane.

8. The temporomandibular joint replacement implant in accordance with claim 6, wherein the jaw component defines a ramus portion wherein the condylar portion predominantly extends medially with respect to the ramus portion.

9. The temporomandibular joint replacement implant in accordance with claim 1 , wherein the articular surface defines a mediolateral elongate axis in the transverse plane.

10. The temporomandibular joint replacement implant in accordance with claim 9, wherein the fossa component defines a lateral flange in a sagittal plane and wherein the articular surface predominantly extends medially with respect to the lateral flange.

11 . The temporomandibular joint replacement implant in accordance with claim

10, wherein in the sagittal plane, the articular surface defines a posterior backstop.

12. The temporomandibular joint replacement implant in accordance with claim

11 , wherein the posterior backstop is defined by a posterior wall of substantially uniform thickness.

13. The temporomandibular joint replacement implant in accordance with claim 11 , wherein in the sagittal plane, the articular surface defines a posterior region and an anterior region and wherein the posterior portion tends to a greater angle with respect to a transverse plane as compared to the anterior portion.

14. The temporomandibular joint replacement implant in accordance with claim 13, wherein in the sagittal plane, the articular surface defines a posteriorly located apex.

15. The temporomandibular joint replacement implant in accordance with claim 2, wherein the jaw component defines a ramus portion and wherein a polymeric condylar portion is removeable from the ramus portion.

16. The temporomandibular joint replacement implant in accordance with claim

15, wherein the ramus portion defines a superior key that fits an inferior socket of the polymeric condylar portion.

17. The temporomandibular joint replacement implant in accordance with claim 1 , wherein the condylar portion defines an ovular section capped by a domed section.

18. The temporomandibular joint replacement implant in accordance with claim

16, wherein the key and the socket are non-rotationally keyed.

19. The temporomandibular joint replacement implant in accordance with claim

18, wherein the key defines longitudinal indentations and wherein the socket defines longitudinal protrusions which key into the longitudinal indentations.

20. The temporomandibular joint replacement implant in accordance with claim 19, wherein the cross-section of the key and socket is nonsymmetric along a longitudinal axis thereof.

21 . The temporomandibular joint replacement implant in accordance with claim 16, wherein the key defines a first side screw hole.

22. The temporomandibular joint replacement implant in accordance with claim 21 , wherein the first screw hole is a blind hole.

23. The temporomandibular joint replacement implant in accordance with claim 16, wherein the condylar portion defines a second side screw hole.

24. The temporomandibular joint replacement implant in accordance with claim

24, wherein the second screw hole is a through hole.

25. The temporomandibular joint replacement implant in accordance with claim 23, wherein the condylar portion defines an annular interface for the second side screw hole.

26. The temporomandibular joint replacement implant in accordance with claim

25, wherein the annular interface defines an annular portion so that a head of a screw configured to engage the first screw hole and second screw hole, can be countersunk.

27. The temporomandibular joint replacement implant in accordance with claim

26, wherein the annular interface comprises a cap which closes over a head of the screw.

28. A method of temporomandibular joint replacement, including the steps of: providing a temporomandibular joint replacement implant in accordance with any one of Claims 1 to 27; preparing the implant site for implantation of the fossa component; attaching the fossa component at the implant site; and engaging the jaw component to the fossa component wherein the non- metallic condylar portion engages the metallic articular surface of the fossa component.