Prosthesis (i.e. – artificial body members) – parts thereof – or ai – Ear or nose prosthesis
Reexamination Certificate
1998-10-07
2001-03-20
Isabella, David J. (Department: 3738)
Prosthesis (i.e., artificial body members), parts thereof, or ai
Ear or nose prosthesis
Reexamination Certificate
active
06203571
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to an ossicular prosthesis of the middle ear, of such a type as to replace at least partly the ossicular chain and to link a first organ or element, particularly the foot plate or the stirrup or stapes, with a second organ or element, particularly the hammer or malleus or the eardrum, which prosthesis can self-adjust by elasticity.
2. Brief Discussion of the Related Art
The middle ear has the task to convey the sound vibrations reaching the eardrum from an aerial environment to a watery environment, namely the inner ear, which constitutes a receiver element of perception of a sound wave.
The conduction of the latter is effected by an anatomic element, called the middle ear conductive system, constituted by a tympanic membrane adjoining an ossicular chain formed, from the outside to the inside, by the malleus, the anvil or incus and the stapes. The tympanic membrane adjoins this chain by the handle of the malleus. The stapes rests on a plate which on its internal base enters into contact with the watery environment, also called labyrinthine environment, of the inner ear.
The function of the ossicles of ossicular chain is to establish the contact between the eardrum and this labyrinthine environment, which constitutes the columellar effect. The ossicular eardrum system is suspended in the aerial cavity of the middle ear. Thus, there is no direct contact of this system with the osseous walls in order to convey acoustic energy originating from the tympanic membrane, namely the external ear, towards the inner ear.
The fixation point of the ossicular eardrum system are two annular ligaments situated at its extremities, namely that of the tympanic membrane and that of the foot plate.
The object of the present invention is to correct the conductive hearing loss, namely resulting from disorders on the ossicular chain after different pathologies.
The ossicular prosthesis for the middle ear have the purpose of replacing, at least partially, this ossicular chain, be it only the incus, the stapes and the incus, or also the stapes, the incus and the malleus.
Until now the available prosthesis are made out of various materials, such as a ceramic material, and consisting of a rod or shaft resting on the head of the stapes or on the foot plate, topped by a platform that makes contact with the handle of the malleus or on the eardrum. Because of the nature of the constructive material, these prostheses present an essentially rigid construction.
This solution presents a number of disadvantages. Thus, first of all, it is necessary that the surgeon has at his disposition a large number of prosthesis of different sizes and shapes, in order to be able to choose among them the most appropriate one for the implantation to be effected.
Furthermore, it is necessary to modify the size of these types of prosthesis, either by cutting them or by milling them so as to adapt their sizes to those of the “defects,” namely of the elements missing from the ossicular chain. This brings about a modification of the condition of the surface of the prosthesis, which contributes to weaken it, to locally modify its interface, and constituting an attraction for an inflammatory reaction.
Lastly, in view of the fact that these prostheses are rigid and have dimensions that cannot be modified, their anchoring point on the elements which they are supposed to link consists of a simple contact, so that the prosthesis is placed only under a passive tension between these elements. This does not allow the reconstitution of a perfectly stable unit, even after an accurate placing of the prosthesis, which explains the many displacements that were observed after an operation. Thus, only about 75% of the partial prostheses, and 50% of the total ones, have shown to have a sufficient mechanical resistance.
In order to remedy these problems of stability, other middle ear prosthesis were suggested, in particular in WO-A-92/18066. This document describes a prosthesis constituted by two independent elements maintained in contact, of which one moves with respect to the other by means of a mechanical spring-system. Such adaptation provides a possibility of deformation of the prosthesis while being its installed. However, the mechanical stresses exercised by these prosthesis on the elements they link are not constant due to the fact of the frictional forces taking place between the two constituent elements of the prosthesis. This leads to a great risk of traumatism at the surfaces of the elements in contact with this prosthesis. Moreover, the latter presents a relatively complex mechanical structure which leads to a high cost, and wherein the functioning can be altered by the presence of tissues at the spring.
SUMMARY OF THE INVENTION
The present invention has the purpose of overcoming the disadvantages of the above described type of prosthesis.
For this purpose, it has as object a middle-ear prosthesis of above-mentioned type, characterized by the fact that it is constituted by an elongated element that comprises an essentially C-shaped or arched section, intended to enter into contact with at least one of the elements with an external surface of at least one of its branches, which branches are suitable to come closer to each other or to move apart by elasticity.
The end of the elongated element designates an element formed, at least partly, by a thin strip.
The prosthesis in accordance with the invention allows to achieve the above-mentioned objectives. Thus, it presents an extremely simple mechanical structure, since it is formed by one only element which, while being installed, does not have to be cut nor milled, which allows the reduction of the risks of an inflammatory reaction and consequently the phenomena of ossicular lysis.
Furthermore, in view of the fact that the branches of the arched section are such that they can come closer to each other or move apart by elasticity, the dimensions of the prosthesis and those that separate the elements it must link are perfectly adapted to each other. The elastic nature of this arched section allows it to self-adjust, not only with respect to the various sizes according to the patients, but also according to the vibrations exercised by the postoperative fibrosis at the eardrum surface. Thus, this ensures a very satisfactory stability of the prosthesis in accordance with the invention.
Furthermore, this arched section presents sufficient flexibility, so that it can be installed without an excessive tension at the time when it is placed and that, after its installation, it can exert an almost constant, permanent tension at its respective anchoring points.
According to a first embodiment of the invention, the arched section is intended to enter into contact with the handle of the malleus and the eardrum by the external surface of its two branches. In this embodiment, the prosthesis in accordance with the invention, constitutes an incus prosthesis allowing to link the malleus and the stapes.
According to an additional characteristic of the invention, a notch intended to house the end-foot of the stapes is provided in the second branch of the arched section. This guarantees a satisfactory, long-term anchoring of the entire prosthesis with the stapes.
According to a second embodiment of the present invention, the arched section is intended to enter into contact with one of the elements by the external surface of a first branch and, at the second branch, it is extended by an essentially rectilinear section. This essentially rectilinear section makes it possible that the prosthesis in accordance with the invention rests against the footplate of the stapes, so that it can constitute either a total incus and stapes prosthesis or also a malleus, incus and stapes prosthesis. This rectilinear section assumes further the function of conveying the sound vibrations to the foot plate of the stapes. In the case of a partial prosthesis, the rectilinear section is essentially arranged in the extension of the second branch, while in t
Giquel Loic
Magnan Jacques
Prandi Bernard
Dowell & Dowell , P.C.
Isabella David J.
Nogitek
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