The subject matter of invention is an auditory ossicles prosthesis, which is attached to the remains of the incus in human's middle ear and to stapes head.

Hearing impairments and related communication disorders constitute a significant health and social problem. Necessary treatment and rehabilitation of patients with hearing impairment is associated with a high economic burden. Therefore, it is of key importance to develop treatment solutions which will be both successful and cost-effective. Patients are provided with various treatment methods depending on the type of disorder and their individual conditions. People with hearing impairment are supplied with numerous electronic devices which support or substitute sensory receptors for hearing. Usually, use of such devices constitutes an indispensable element of treatment part of which relates to intensive rehabilitation. Diagnosis and treatment is provided by the interdisciplinary team of specialists. Auditory system is divided into two subsystems: the central auditory system and peripheral auditory system. The peripheral auditory system consists of the outer ear, middle ear and inner ear. Most structures constituting peripheral auditory system are located in temporal bone. The outer ear has two basic functions. First, it protects underlying structures. Second, pinna collects sound waves and - as a result of resonance - it amplifies the amplitude of the incoming sound wave of frequency around 3000 Hz. Then sound is transmitted via auditory canal to the eardrum, where sound waves turn into mechanical vibrations. In the middle ear the ossicles, i.e. malleus, incus and stapes, transfer further the modified and amplified signal. The last of the ossicles is attached to the membrane of the oval window and transmits sound vibration into the inner ear. The oval window is usually treated as a one of the elements of the inner ear. Sound transmission in the middle ear enable for 22 - fold increase of the input sound pressure level (dB SPL) by: a) reducing the surface to which the energy is applied from about 55 mm ² on the eardrum to about 3,2 mm ² on the oval window and b) use of leverage effect between malleus and incus (ratio 1 :3). Young, healthy adult hear sounds of frequency about 20-20.000 Hz and intensity between 0 dB and 125 dB SPL (pain threshold). However, about 50% of people above 65 years of age suffer from a variety of hearing impairments. In most cases hearing impairment is sensorineural (WHO, 2000). This means that the dysfunction of the auditory system is connected to malfunction of the cochlea or the vestibulocochlear nerve. Such a hearing impairment may be gradable - from mild to profound. One of the most common problems connected with the sensorineural hearing impairment is the decrease of the frequency discrimination, which impedes the ability to understand speaking language while in noise and (Kutkami et al., 2008). The second type of hearing impairment, which is distinguished because of the place where the dysfunction occurs, is the conductive hearing impairment. This type of hearing impairment results from the dysfunctionality of the structures located within the outer ear or middle ear. In case of the conductive hearing impairment the sound transmission to the inner ear is limited or blocked due to pathologies of the auditory ossicles, inherent atresia (underdevelopment of the outer ear - known as microtia), tumor, chronic inflammation of the outer ear or eardrum as well as by skin problems within ear. The third type is the mixed hearing loss, which combines components of both abovementioned types of hearing impairment. The structures of the hearing organ may be artificially stimulated using various mechanisms where a) the eardrum is put into vibrations by acoustic signal in case of correct hearing or by hearing aid in case of hearing impairment, b) the structures of the middle ear - i.e. the chain of auditory ossicles, oval and round window as well as the temporal bone are mechanically stimulated (conventional hearing aids, bone anchored hearing aids, middle ear implants), c) the sensory nerve endings are electrically stimulated (cochlear implants, brainstem and midbrain implants), d) cochlear and stem implants, which would provide stimulation by optical impulses but are still in the research phase. Apart of experimental research, the medial geniculate nucleus, olivary bodies or hearing cortex are not directly stimulated, as the mechanisms of signal coding and maps of tonotopy stimulations are not well-known in this areas as well it is difficult to predict the scope of the neuroplasticity in this area (Zeng and co., 2011).

One of the alternative method of treatment of the conductive hearing impairment instead of implanting active systems is the use of devices which simulate the activity of auditory ossicles. Such prosthesis replaces all the structures or fragments of the ear structures which are missing, damaged, deformed or stiffened because of various diseases of the middle ear, such as e.g. ostoclerosis. Standard material used to produce such passive devices (which do not require external power supply, also known as body-powered prosthesis) is titan due to its high biocompatibility rate as well as due to its relative stiffness and flexibility. Recently, the body powered prosthesis is produced also from nickel, as it is a highly flexible and corrosion resistant material. In case of the newest models of body powered prosthesis, it is possible do choose shape and size of each element of the prosthesis as well as to adjust it to the anatomical conditions of the patient during the surgery (Martin and co., 2011). Some of the devices are used in ossiculoplasty operations, i.e. filling or replacing elements of chain of auditory ossicles. Typically, the body powered prosthesis combines a round head with an open form on one hand, which is implemented in a way which allows it to almost completely adhere to the eardrum and limits the risk of damaging it and at the same time immobilizes the prosthesis (typical measure of the head is 2-4 mm). The length of handle of the prosthesis, which comes from the other side to the plate (base) of the stapes in the niche of the oval window, can be, depending on the model used, adjusted to anatomical conditions of patients within the scope of 2-7 mm. There exists also body powered prosthesis, which are attached with one side to the eardrum and with the other side to stapes head with a clip-on. There are also available devices which replace only single elements of the chain of auditory ossicles, i.e. manubrium of the malleus, fragments of the incus or the incudomalleolar joint. Another type of treatments, where the prosthesis to the middle ear are used are the stapes surgeries, which are required due to otimmobility caused by ostoclerosis. Usually, such prosthesis is placed between the long process of the incus and the oval window niche (or the base of stapes) (Martin and co., 2011). Another type of prosthesis is composed of two basic elements: a) loop, which is stably attached to incus and consequently allows to reduce the pressure and optimize sound transmission and b) handle (3-7 mm long). unitary body of deformable material capable of retaining different shapes. The body comprises a slotted wall defining a cavity for receiving a bone of the middle ear.

European patent application No. BP 17S9662 discloses endoprosthesis of the middle ear which comprises a member adapted to supplement an ossicular bone when implanted in an ear. An anatomically conforming structure is secured to the member comprising an upper arcuate portion and a lower arcuate portion, each having near and distal ends respectively. A crimp assist portion is connected to the near ends of the upper and lower arcuate portions so that the upper and lower arcuate portions generally define portions of a circle for partially surrounding a bone. The crimp assist portion extends outside of the circle.

European Patent No. EP2798311 discloses an ossicular prosthesis intended to replace at least one piece of the chain of ossicular bones. The prosthesis elongated body has a first coupling element designed as an eardrum top plate or a clip connecting with piece of ossicular bone or a connecting piece to an actuator end piece of an active hearing implant. The other side of the elongated body of the prosthesis has an element coupling with stapes. It is designed as a bell or a clip with a hole enabling for an access to the head of the stapes and to the receiving space to constant location of stapes head. The element coupling the prosthesis with the stapes has a backing section on an inner surface of the receiving space of the location of the stapes head as an axial extension of the elongated prosthesis body in relation to stapes head after the implementation of the prosthesis.

European Patent No. EP1181907 discloses a prosthesis of a chain of middle ear ossicles which comprises a self-supported clip mounted at a stapes. The clip comprises spring tongues which are put axial over the stirrup, whereby the clip encloses the stirrup at four sides. The prosthesis can act as a passive implant as well as an element coupling with active hearing aid. Industrial design application No. DE20201410151 describes passive ossicular prosthesis used to substitute or to bridge at least one of the ossicular bones. The prosthesis is ended with a loop for a mechanical connection of the prosthesis with one of the ossicular bones. The loop is made of perforated metal strip.

European Patent No. EP149S737 discloses an auditory ossicles prosthesis consisting of two elements: a first rod with a clip at one end to clip to the malleus mounting of the inner ear and a second rod with a plunger shaped end insertable directly into cochlea via oval window. The two rods are linked by at least one joint.

The invention relates to an auditory ossicles prosthesis consisting of main beam (1) provided with three hooks (23.4). The hooks are fastened with one side to the stapes head and with the other side to the remains of incus. Stapes head hook (2) constitutes three identical or different, bended arms (S) going out of the main beam (1) with additional side arms (6) in arcuate shape, situated in the plane parallel to the main beam (1) and perpendicularly to the arms (5). In principle, there is right angle between the neighboring arms (5) and distant arms (5) and the main beam (1). The arms (S) constitute a type of a basket with clamps made of the arms (6) and are in the shape of fragments of circles. The hook (3) to the long process of the incus is made of two symmetrical, bended arms (7) on both sides of the main beam (1), situated approximately within half of the length of the implant and perpendicularly to the main beam (1). The third hook (4) is situated on the extension of the main beam (1). The hook (4) has a changeable cross-section which decreases proportionally to the increase of the distance to the main beam (1) and is wrapped around the remains of the incus and is used as an additional stabilizer. In case of a particularly preferable realization the prosthesis is wholly made of titan. It is preferable when the main beam (1) has a cross-section in the shape of a rectangle. It is preferable as well, when the arms (5) have the same cross-section as the main beam (1). In another preferable realization of the prosthesis all the beams (6) have the same cross-sections. It is also favorable when the hook (4) has the shape of an extended pyramid with a rectangular base and its measures are equal with the measures of the cross-section of the main beam (1).

The structure of the invention allows for adjusting the position of the implant to the anatomical structure of patient's middle ear as well as adjusting it to the form of the defected auditory ossicles of the middle ear. The construction of the hooks gives a stable connection with the auditory ossicles and the structure of the prosthesis enables the surgeon to tighten the implant during the implementation.

The subject of the invention has been described on the illustration, where fig. 1. displays the view of the prosthesis, figure 2. displays view from the front of the prosthesis, fig. 3. displays perspective of the prosthesis.

EXAMPLE

The auditory ossicles prosthesis composes of main beam 1 provided with three hooks 2,3.4. The hooks are attached to the stapes' head and with the other side are mounted to the remains of incus. Stapes head hook 2 constitutes three bended arms S with identical cross-section going out of the main beam 1 with additional side arms 6 in arcuate shape, which constitute fragments of circles that are situated in one plane parallel to the main beam 1. The side arms 6 are situated perpendicularly to the arms S. All side arms 6 have identical rectangular shape of the cross-section. There is right angle between the neighboring arms S and distant arms 5 and the main beam 1. The arms S constitute a type of a basket with clamps made of the arms 6, which are in the shape of circles. The hook 3 to the long limb of the incus is made of two symmetrical, bended arms 7 of rectangular cross-section, situated on the sides of the main beam 2 approximately within half of the length of the implant. The third hook 4 is not symmetrical and is situated on the extension of the main beam 2. The hook 4 has the shape of an extended pyramid with a rectangular base and its measures are equal with the measures of the cross-section of the main beam 1 and is wrapped around the remains of the incus and is used as an additional stabilizer. The prosthesis is made of titan.