PROSTHESIS FOR A TEMPOROMANDIBULAR JOINT

Abstract

Prosthesis (1) for the mandibular side of a temporomandibular joint, comprising a head part (2) to replace the condylar head, in particular at the anatomic location, and an attachment plate, wherein the attachment plate is saddle-shaped having a lateral portion (3) and a medial portion (4) that have been formed and are intended for abutting both sides of the ascending branch of the mandible, straight below the arcuate notch in the upper end of the ascending branch of the mandible.

Claims

1-21. (canceled)

22. A prosthesis for the mandibular side of the temporomandibular joint, comprising a head part to replace the condylar head, in particular at the anatomic location, and an attachment plate for attachment to the mandible, wherein the attachment plate has been formed having a lateral portion that has been formed and is intended for abutting the lateral side of the ascending branch of the mandible, straight below the arcuate notch in the upper end of the ascending branch of the mandible, wherein the lateral portion has been provided with holes for attachment to the lateral side of the ascending branch of the mandible, wherein the attachment plate comprises an upper portion forming one unity with the lateral portion and formed and intended for abutting the concave upper edge of the arcuate notch in the upper end of the ascending branch of the mandible.

23. A prosthesis according to claim 22, wherein the attachment plate comprises a medial portion that forms one unity with the lateral portion and upper portion, and that has been formed and is intended for abutting the medial side of the ascending branch of the mandible, preferably straight below the arcuate notch in the upper end of the ascending branch of the mandible.

24. A prosthesis according to claim 22, wherein only the lateral portion has been provided with holes for attachment to the lateral side of the ascending branch of the mandible.

25. A prosthesis according to claim 22, wherein, in a direction parallel to the direction of projection of the head part, the lateral portion has a length that is smaller than its length in a direction transverse thereto.

26. A prosthesis according to claim 22, wherein the lateral portion is sickle-shaped.

27. A prosthesis according to claim 22, wherein the medial portion is sickle-shaped.

28. A prosthesis according to claim 22, wherein at least one of the lateral portion and the upper portion has been configured for in the placed condition extending in the ventral direction to beyond the lowest point of the arcuate upper edge, that means up into the area situated straight below the portion of the said upper edge which is ascending in the ventral direction in the direction of the coronoid process.

29. Prosthesis according to claim 23, wherein the medial portion has been configured for in the placed condition extending in the ventral direction to beyond the lowest point of the arcuate upper edge, that means up into the area situated straight below the portion of the said upper edge which is ascending in the ventral direction in the direction of the coronoid process.

30. A prosthesis according to claim 22, wherein at least one of the lateral portion and the upper portion has been formed and is intended to extend up to the coronoid branch.

31. A prosthesis according to claim 23, wherein the medial portion has been formed and is intended to extend up to the coronoid branch.

32. A prosthesis according to claim 22, wherein the head part and the attachment plate form one unity with each other.

33. A prosthesis according to claim 23, wherein the attachment plate has the look of a saddle, in particular the look of a hyperbolic paraboloid.

34. An assembly of a prosthesis according to claim 22 and a prosthesis for the fossa glenoidalis (glenoid cavity or glenoid fossa) as bearing part for the head part.

35. A method for replacing the condylar head in a patient by a condylar head prosthesis, wherein the shape of the edge of the arcuate notch in the upper end of the ascending branch of the mandible is defined and the prosthesis according to claim 22 is also designed and made on the basis thereof, after which the prosthesis is being placed on the ascending branch of the mandible in question.

36. A prosthesis for the mandibular side of a temporomandibular joint, comprising a head part to replace the condylar head, in particular at the anatomic location, and an attachment plate, wherein the attachment plate comprises a lateral portion and a medial portion that have been formed and are intended for abutting the lateral and medial sides, respectively, of the ascending branch of the mandible, straight below the arcuate notch in the upper end of the ascending branch of the mandible, and having an upper portion forming one unity therewith, being formed concave with the cavity facing upwards, when considered in a direction transverse to the lateral portion, and being formed concave, with the cavity facing downwards, when considered in a cross-section.

37. Prosthesis according to claim 36, wherein, in a direction parallel to the direction of projection of the head part, the lateral portion has a length that is smaller than its length in a direction transverse thereto.

38. Prosthesis according to claim 36, wherein at least one of the lateral portion and the medial portion is sickle-shaped.

39. Prosthesis according to claim 36, wherein at least one of the lateral portion, the upper portion and the medial portion has been configured for in the placed condition extending in the ventral direction to beyond the lowest point of the arcuate upper edge, that means up into the area situated straight below the portion of the said upper edge which is ascending in the ventral direction (in the direction of the coronoid process).

40. Prosthesis according to claim 36, wherein at least one of the lateral portion, the upper portion and the medial portion has been formed and is intended to extend up to the coronoid branch.

41. Prosthesis according to claim 36, wherein the head part and the attachment plate form one unity with each other and wherein the attachment plate has the look of a saddle, in particular the look of a hyperbolic paraboloid.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0034] The invention will be elucidated on the basis of an exemplary embodiment shown in the attached drawings. The views are named in accordance with the side in question, that means that a lateral view is a view from the lateral side. In which:

[0035] FIGS. 1A-E show a medial side view, a lateral side view, a postera-lateral view, a postera-medial view and a view in cross-section according to plane IE in FIG. 1B, respectively, of the mandibular component of the jaw joint prosthesis to be placed on a mandible;

[0036] FIGS. 2A and 2B show a postera-lateral view and a postera-medial view, respectively, of a fossa component of a jaw joint prosthesis to be placed on a maxilla;

[0037] FIGS. 3A and 3B show a postera-lateral view and a postera-medial view of an assembly of the mandibular component of FIGS. 1A-E and the fossa component of FIGS. 2A, B; and

[0038] FIGS. 4A and 4B show a lateral and a medial side view, respectively, of an assembly according to the invention in the placed condition.

DETAILED DESCRIPTION OF THE DRAWINGS

[0039] FIGS. 1A-D show the mandibular component 1 of a temporomandibular joint prosthesis (TMJ prosthesis), which comprises a lateral wing 3 and a medial wing 4, that are connected to each other by an upper portion or ridge 5 forming one unity therewith. The lateral wing 3 has been provided with bone screw holes 6. It is clear to see that the component 1 is saddle-shaped, has an inverted U-shape in ventral and dorsal view, and is U-shaped in side view (when considered transverse to the lateral portion, see FIG. 1D). The attachment plate in this case has a double concave shape, both concave shapes being oriented in an opposing manner (upwards and downwards) and rotated over approximately 90 degrees relative to each other. The attachment plate may also have the look of a hyperbolic paraboloid.

[0040] At the rear end via a neck 8, an artificial condylar head 2 projects upwards, like a kind of saddle horn or pommel. The rear edges 3a and 4a of both wings have been indicated in FIG. 1C. As can be seen in FIGS. 1A and 1C a downwardly extending pin 7 has been provided within the component 1 at the rear end, which pin remains spaced apart from both wings 3 and 4. Said pin 7 is optional and may have been provided as intramedullary pin.

[0041] The mandibular component has been manufactured as one unity from titanium or tantalum, or from an alloy thereof, from PEEK or UHMWPE, or a composition of these or other materials, preferably manufactured using additional manufacturing and/or CNC robotic milling.

[0042] The mandibular component has been designed and manufactured in correspondence with the shape and condition of the ascending branch of the mandible of the patient in question, such that both wings fittingly abut the ascending branch of the maxilla, wherein the artificial condylar head 2 replaces the condylar head at the anatomic location, and the upper portion fittingly abuts the upper edge of the incisura semilunaris.

[0043] Depending on the circumstances, the medial wing may have been shaped differently, for instance be narrower, be L-shaped, or consist of several lips, for instance one lip near the condylar neck and one lip near the coronoid process.

[0044] Depending on the circumstances, the lateral wing may have been shaped differently, for instance be narrower, be L-shaped, or consist of several lips, for instance one lip near the condylar neck and one lip near the coronoid process.

[0045] The upper portion may further be interrupted in ridge direction, instead of continuousas depicted in FIGS. 1A-D.

[0046] FIGS. 2A and 2B show a fossa component 10 for a TMJ prosthesis, which component is to be placed at the temporal side and capable of working together with the mandibular component 1. The fossa component 10 forms an elongated, downwardly opening socket 11 in which the artificial condylar head 2 is able to rotate and shift, as much in line with a natural jaw joint as possible. For attachment in the base of the patient's skull, bone screw holes 12 have been provided.

[0047] The fossa component may have been manufactured, optionally as one unity, from titanium or tantalum, or from an alloy thereof, from PEEK or UHMWPE, or a composition of these or other materials, preferably manufactured using additional manufacturing and/or CNC robotic milling. In one embodiment, the portion having the holes 12 has been made of metal, the portion of the socket 11 has been made of UHMWPE. The downwardly oriented bearing surface has a horizontal lip 14 at the front end and vertical lips 13 at the rear end and at the medial side in order to prevent luxation and reankylosis.

[0048] The fossa component has been designed and manufactured in correspondence with the shape and condition of the zygomatic arc and the glenoid cavity, including articular tubercle (tuberculum articularis), and in correspondence with the mandibular component.

[0049] FIGS. 4A and 4B show a left half 100 of the mandible, including the ascending branch 101 (ramus mandibulae), the coronoid process 102 and the condylar process 103. When considered in a direction from rear to front (dorsal-ventral), the condylar process 103 merges into the coronoid process 102, via a concave ridge or upper edge 104 limiting the incisura semilunaris 105 in downward direction. Line 107 indicates the lower edge of the fossa infratemporalis.

[0050] After preparatory actions, such as the surgical resection of the diseased condylar head (portion) and once the area has been made accessible by an incision in the area at the height of the temple (wherein the area of the jaw angle 106 is left virtually undisturbed), the mandibular component 1 is as it were placed like a saddle, the upper portion 5 resting on the concave ridge 104 and both wings 3 and 4 on either side, abutting both sides of the maxilla. As can be seen in FIG. 3A, the height h of the lateral wing 3 relative to the lowest point M of the ridge is approximately half the height or less of the ascending branch of the mandible 101, and the wing 3 remains above the buccal branch of the facial nerve. It can further be seen that in forward direction, the component 1 extends amply beyond the location M of the lowest point of the ridge 104. The saddle 1 is attached to the ascending branch 101, in its upper half, by means of bone screws in the holes 6 in the lateral wing 3.

[0051] The fossa component 10 is also placed and attached to the temporal bone 110 (os temporale) using bone screws in holes 12.

[0052] The saddle-shaped condylar head prosthesis according to the invention provides abutting contact with the bone on both sides of the ascending branch of the mandible, which enhances the stability and ingrowth of bone tissue. This considerably reduces the risk of the prosthesis getting dislodged.

[0053] The chewing forces are absorbed by the prosthesis 1 and transferred by it in a distributed manner to the mandible, namely to the condylar stump of the ascending branch, by pressure on the ridge and by transverse forces on the bone screws at the lateral side.

[0054] The relatively large surface of the lateral wing increases the freedom of choice in number and location of the holes for the bone screws.

[0055] In one embodiment, there is no medial wing in the mandibular component. The upper portion or ridge (which in that case is concave in cross-section, the cavity facing downwards) then extends onto/supports on the upper edge/ridge. The medial wing may also be short, when considered in downward direction, for instance in the form of an edge only just extending over the upper edge/ridge, so that in cross-section the look of a hook is realized.

[0056] The invention is/inventions are not at all limited to the embodiments discussed in the description and shown in the drawings. The above description has been included to illustrate the operation of preferred embodiments of the invention and not to limit the scope of the invention. Starting from the above explanation many variations that fall within the spirit and scope of the present invention will be evident to an expert. Variations of the parts described in the description and shown in the drawings are possible. They can be used individually in other embodiments of the invention(s). Parts of the various examples given can be combined together.