FR2691354A1 - Mechanical prosthesis for middle ear bones - comprises metal wire bent to define part-rigid, part-flexible shaft linking drum component to bearing surface of stirrup bone - Google Patents

Abstract

The prosthesis for middle ear bones consists of a drum-type assembly, with a mechanical connecting shaft bearing against the plate surface of the stirrup bone. The connecting shaft is formed from elastic material. The connecting shaft may be of composite construction, consisting of a rigid portion (3) and a flexible portion (2), both formed of metal wire bent into the required shape. ADVANTAGE - Simplified mechanical construction, with reduced risk of rejection of implant.

Description

OSSICULAR PROSTHESIS FOR THE EAR
The present invention relates to an ossicular prosthesis intended to be implanted in the middle ear after destruction of certain ossicles.

The tympano-ossicular system is part of the middle ear and is made up of the eardrum, which is a resonant membrane on which the hammer handle, the first element of the ossicular chain, is inserted.

The ossicular chain includes three elements: the hammer, the anvil and the stirrup, it connects the eardrum to the cochlea which is the very organ of sensory perception, transforming vibratory information into nerve impulses.

The ossicular chain transmits the vibrations of the eardrum to the cochlea, while reducing their amplitude by a double lever effect. This purely mechanical phenomenon, associated with the difference in surface area between the eardrum and the stirrup plate, generates an amplification of the sound with a gain of around 30 dB. There are pathologies, and in particular chronic otitis, which destroy the eardrum and fiou the ossicles, thus causing a deafness of transmission.

 It is known to remedy hearing loss, either by electro-acoustic devices, or by replacing the destroyed organs. A second solution uses tympanoplasty, ossicular prostheses and possibly grafts.

 There are already ossicular prostheses which are limited to re-establishing contact between the eardrum (possibly reconstructed) and the stirrup or its plate when the latter is partially destroyed. The stirrup plate is indeed very often preserved, both in its anatomical integrity and in its mobility, as well as in its connections with the cochlea.

The known prostheses are in the form of rigid rods made of hydroxyapatite, stainless steel or composite materials and we have been able to observe rejection or extrusion phenomena through the eardrum due to the mechanical forces exerted on this membrane, or more rarely, of insertion of the platinum in the palatine, with opening of the inner ear which leads to definitive deafness.

The object of the present invention is to overcome this drawback.

According to the present invention, the ossicular prosthesis comprising a tympanic support, a platinum support and a mechanical connecting rod is characterized in that the connecting rod is elastic.

Thus, the rejection phenomena mentioned above no longer occur and there is a characteristic of the natural ossicular chain which is elastic by the articulation of the ossicles one on the other.

This elasticity also provides temporary support during installation. In addition, this prosthesis has good adaptability to anatomical variations, the tympanic-platinum distance, of the order of 7 to 10 mm, varying from one ear to the other. Of course, this elasticity can be produced by different means and in particular, according to another characteristic of the invention, by the fact that the transmission rod is connected to the tympanic support by a bent metal wire.

Other characteristics and advantages of the invention will appear during the following description of a particular embodiment given by way of nonlimiting example with reference to the figures which represent: - Figure 1, a schematic front section natural ear; - Figure 2, a view of the prosthesis according to the invention; - Figure 3, a view of the prosthesis in position in the middle ear.

Figure I schematically represents the section of an ear on which we distinguish the external auditory canal (CAE) which is open on the outside and which ends in the eardrum (T) which separates it from the middle ear (OM) . The middle ear is an air cavity that communicates with the nose via the Eustachian tube.

Inside the middle ear are three ossicles, respectively the hammer (M), the anvil (EC) and the stirrup (ET) which is very small. In the event of destruction of the ossicles, the stirrup plate generally remains intact.

FIG. 2 represents a prosthesis according to the invention. In the embodiment shown, the prosthesis generally designated by the reference 10 comprises a tympanic support 1 which may for example be elliptical on which is fixed an elastic branch 2 bent, itself connected to a connecting rod 3 The lower part of the rod 3 comes into contact with the caliper plate.

The elastic branch can be, for example made of stainless steel wire and the other components of Teflon, hydroxyapatite, PMMA or the like.

FIG. 3 schematically represents a prosthesis 10 implanted in the chamber of the middle ear, after sub-total destruction of the ossicular chain. The tympanic support 1 is disposed at a point on the internal face of the eardrum and the rod 3 bears on the plate of the stirrup.

 It goes without saying that many variants can be introduced, in particular by substitution of technically equivalent means, as well as in the preparation of partial prostheses when the stirrup is intact, without thereby departing from the scope of the invention.

Claims (2)

I. Ossicular prosthesis comprising a tympanic support, and a mechanical connecting rod bearing on the plate of the stirrup, characterized in that the connecting rod (2, 3,) is elastic. 2. Prosthesis according to claim I, characterized in that the transmission rod is constituted by a rigid part (3) and a flexible part (2}, formed by a bent metal wire.