WO2013138818A1

WO2013138818A1 - Partial or complete middle ear prosthesis

Info

Publication number: WO2013138818A1
Application number: PCT/ZA2012/000015
Authority: WO
Inventors: Mashudu TSHIFULARO
Original assignee: Tshifularo Mashudu
Priority date: 2012-03-16
Filing date: 2012-03-16
Publication date: 2013-09-19
Also published as: ZA201407457B

Abstract

The invention provides a stapes prosthetic for use in the middle ear of a person. The prosthetic includes a stapes connection means configured for connecting to the stapes or part thereof or incus; a vibration transmission means for transmitting vibrations to the oval window of the middle ear; and a connecting body which connects the stapes connection means and the vibration transmission means.

Description

Title: Partial or Complete Middle Ear Prosthesis

Technical field of the invention This invention relates to partial or complete middle ear prosthesis.

Background to the invention

The middle ear is a hollow space, the portion of the ear internal to the eardrum, and external to the oval window cf the cochlea. The middle ear, also called the tympanic cavity, or cavum tympani contains three ossicles, which amplify vibration of the eardrum into pressure waves in the fluid in the inner ear. When sound is transferred from an air medium to a liquid medium most of the sound is reflected and the middle ear allows the impedance matching to overcome the interface between air and liquid. The middle ear functions as a sound amplifier. The ossicles: malleus, incus, and stapes, are also known as the hammer, anvil, and stirrup, respectively. The ossicles directly couple sound energy from the ear drum to the oval window of the cochlea.

There are several specific ways in which the middle ear amplifies sound from air received at the tympanic membrane to the fluid in the oval window. The first of these is the "hydraulic principle". The vibratory portion of the tympanic membrane is many times the surface area of the footplate of the stapes. The collected pressure of sound vibration that strikes the tympanic membrane is concentrated down to this much smaller area of the footplate, increasing the force and thereby amplifying the sound. The second way in which the middle ear amplifies sound is by means of the "lever principle". The shape of the articulated ossicular chain is like a lever, the long arm being the malleus, and the body of the incus being the fulcrum or pivot point and the short arm being the incus.

The third way in which the middle ear amplifies sound is by "round window protection". The cochlea is a fluid filled tube, wound about on itself. One end of this tube is at the oval window, the other end is at the round window. Both of these windows, opening in the bone, lay on the deep wall of the middle ear space. Whereas the tympanic membrane and ossicular chain preferentially direct sound to the oval window, the round window is protected by middle ear structures from having sound waves impinge on its surface. The middle ear structures that protect the round window are the intact tympanic membrane and the round window niche. If there were no tympanic membrane or ossicular chain, sound waves would strike the round window and oval window at the same time which cancels the energy of the sound transmission.

Importantly, the middle-ear is able to dampen sound conduction a bit when faced with very loud sound by noise induced reflex contraction of the middle ear muscles, which inhibits the movement of the ossicles. The movement of the ossicles can be inhibited by two muscles, the stapedius and tensor tympani, which are under the control of the facial nerve and trigeminal nerve, respectively. These muscles contract in response to loud sounds, thereby reducing the transmission of sound to the inner ear. This is called the acoustic reflex. The auditory ossicles can also reduce sound pressure by uncoupling each other through particular muscles.

The ossicles mechanically convert the vibrations of the eardrum, into amplified pressure waves in the fluid of the cochlea (or inner ear) with a lever arm factor of 1.3. Since the area of the eardrum is about 17 fold larger than that of the oval window, the sound pressure is concentrated, leading to a total amplification of at least 22. The eardrum is fused to the malleus, which connects to the incus, which in turn connects to the stapes. Vibrations of the stapes footplate introduce pressure waves in the inner ear. Of surgical importance are two branches of the facial nerve which also pass through the middle ear space. These are the horizontal and chorda tympani branches of the facial nerve. Damage to the horizontal branch during surgery can lead to partial, unilateral facial paralysis. In summary, the amplification system and loud noise dampening system described above is a delicate sum of the function of all the parts of the inner ear.

The inventor is aware that normally, for persons affected by otosclerosis, the footplate of the stapes fixates at the footplate annulus ligament and not the stapes bone itself. A stapedectomy is performed to try and restore hearing to some extent. A stapedectomy includes complete removal of the stapes, its suprastructure, stapedial tendon and incostapedial joint, most of which is still functioning properly. The removal of these functioning components interferes with the delicate amplification and loud sound dampening system of the inner ear.

The inventor is further aware that the malleus and/ or incus may be affected for the same reasons the stapes may be affected or due to trauma, infection or congenital reasons. Currently, if more than one ossicle is affected the patient undergoes total ossicle replacement, including unaffected ossicles, in an attempt to restore hearing to some extent. The current prosthetics also does not take the normal anatomy and function of the human ossicles into account which, the inventor believes, is part of the reason of the low or partial success of the procedure.

It is an object of this invention to provide a prosthesis which will replace only the function of the ossicle or ossicles which are not functioning properly and, in the case of a stapedectomy, not the whole stapes, its suprastructure, stapedial tendon and incostapedial joint. It is a further object of this invention to simplify the stapedectomy procedure and to increase its chances of success with minimal intrusion trauma and chance of facial paralysis.

It is a further object of the invention to provide prosthesis for any one or more of ossicles which are damaged without the need to remove healthy or healthy parts of the ossicles of a person. It is a further object of the invention simplify the surgical procedure and for the prosthesis to have similar functionality compared to the removed tissue.

General description of the invention

According to the invention there is provided a stapes prosthetic for use in the middle ear of a person, which prosthetic includes:

a stapes connection means configured for connecting to the stapes or part thereof or incus;

a vibration transmission means for transmitting vibrations to the oval window of the middle ear; and

a connecting body which connects the stapes connection means and the vibration transmission means.

It will be appreciated that connection to the incus would be for total stapes replacement. In one embodiment, the stapes connection means may be a spring- loaded tie-on for tying onto the long process of an incus.

The connecting body may be an elongate connector extending from the tie-on, which connector is configured to be length adjustable and which may include a shock absorber.

The vibration transmission means at the free end of the connecting body means may be configured to interact with the oval window or part thereof.

The tie on may be c-shaped and spring loaded and biased in the closed position. In this embodiment, the tie-on will not clamp onto the long process but rather tie on to it without cutting of blood flow yet will stay in place. Alternatively, the tie-on may be a clamp and may be c-shaped and may be biased in the closed position with a force selected that is optimal for connection to the long process without cutting of blood flow yet will stay in place. Preferably, the tie on may be a springloaded wire a-loop. The wire may be ribbon shaped. The spring force may be selected to clip onto the long process without cutting of blood flow yet stay in place.

The tie-on may include forceps engaging members configured such that a forceps can engage the clamp and allow a person to urge the tie-on into an open position to allow the tie-on to engage the long process during surgery.

The elongate connector is also known as a piston. The piston may be in the form of a rod inside a sleeve, with a spring or other biasing means housed or captured inside the sleeve.

The rod may be provided with a thread and at its tie-on side and may be threadedly received inside the spring to allow the connector to be length adjustable. Alternatively, the rod may be provided with a thread at its free end, which may be threadedly received in a threaded socket provided in the oval window engagement means.

The vibration transmission means may be an oval window engagement means, and may include a cylindrical portion at its free end followed by a skirt or pair of shoulders followed by the rod. The skirt or pair of shoulders help prevent the vibration transmission means from going to deeply in to the inner ear. (pseudo stapes footplate) The clamp may be manufactured from titanium (spring mechanism) and bone cement.

The vibration transmission means, may be in the form of a modelled prosthesis of spring, bone cement and tiranium configured to normal looking ossicles to protrude through' a hole which is surgically incised through the footplate membrane of the oval window in contact with the gel tissue of the inner ear and may then also include a shoulder around its periphery to inhibit penetration into the inner ear to a certain predetermined depth. The prosthesis may be dimensioned to fit through a hole as described above or alternatively, the prosthesis may be generally oval in cross section and dimensioned replace the footplate of the oval window, which is surgically removed, and may then include a shoulder around its periphery to inhibit penetration into the inner ear to a certain predetermined depth. The prosthesis may be of a resiliently deformable or shock absorbing material by a spring mechanism.

In the case of a total stapes prosthesis, the prosthetic posterior and anterior cms may be each be provided with braces for fitting onto and bracing against the remaining part of the footplate.

The prosthesis may be manufactured from titanium, bone or dental cement, Teflon and/ or flueroplastin. The connecting body may be manufactured from titanium and bone cement/dental.

The part of the vibration transmission means which is in contact with the oval window or inner ear may be of a shock absorbing material such as resiliently spring (titanium), deformable gel, fatty tissue or like material.

The invention further provides a malleus replacement prosthetic, which is shaped and configured to resemble a natural malleus and includes an attachment means for attachment to a tympanic membrane or part or remainder of a tympanic membrane, at one side and on the other side a connection means for connecting to an incus or incus replacement prosthetic by means of a movable malleoincus joint to allow sound transmission. The tympanic membrane connection means may include a silastic sheet for attachment to a tympanic membrane or to accept a replaced tympanic membrane. The connection' means for connecting to an incus or incus replacement prosthesis may include a u-channel shaped spring-loaded clamp, which can grip anywhere along the bony annulus of the incus to compensate for different anatomies and sizes of the patient. The clamp may include jaws provided with teeth for a secure grip.

Similarly, the invention further provides an incus replacement prosthetic, which is shaped and configured to resemble a natural incus and includes a malleus attachment means for attachment to a malleus or malleus replacement, at one side and on the other side a connection means for connecting to a stapes or stapes replacement prosthetic by means of a movable incostapedial joint to allow sound transmission. The connection means for connecting to a malleus may be a ridge formation resembling a natural bony annulus to accept a clamp from a malleus prosthetic. Alternatively, the clamp may be located on the incus prosthesis and the ridge on the malleus prosthesis. The connection means for connecting to the stapes may be in the form of a springloaded clamp for clamping onto the head of the stapes. The clamp may include jaws provided with teeth for a secure grip.

The body of the incus is elongate and the length of the body of the incus prosthetic may be adjustable. The adjustability may be in the form of a piston ad sleeve configuration and optionally it may be configured to absorb shock or excessive vibration from loud noises.

The invention also extends to a use of the prosthetic described above to treat otosclerosis or any ailment which requires a stapedectomy procedure or osciculoplasty. The invention also extends to a surgical method which includes the steps of:

severing the posterior and anterior cms; either removing the footplate(stapedectomy) or incising a hole through the foot plate(stapedotomy); and either clamping a pair of clamps of the prosthesis to the posterior and anterior cms. It will be appreciated that minimal components and its associated functionality of the middle ear ossicles are removed and that the procedure carries significantly less risk than known prosthetics and its associated surgical procedure. Detailed description of the invention

The invention is now described by way of example with reference to the accompanying drawings. In the drawings:

Figure 1 shows a Total Supra-structure Prosthesis (TSP) for use in the middle ear of a person, with the a loop tie-on in the closed position, in accordance with the invention;

Figure 2 shows the interaction of the vibration transmission means of the TSP with a tympanum;

Figure 3 shows a Minimal Stapes Supra-structure Prosthesis (MSSP) in stapedectomy;

Figure 4 shows a malleus prosthetic and incus prosthetic for middle ear partial ossicular replacement prosthesis;

Figure 5 shows a Total Ossicular Replacement Prosthesis (TORP);

Figure 6 shows a Partial Ossicular Replacement Prosthesis (POP);

Figure 7 shows a stapes prosthetic for use in the middle ear of a person, with the tie-on in the open position, in accordance with the invention; and

Figure 8 shows a stapes prosthetic for use in the middle ear of a person, with the tie-on in the closed position.

In the embodiment shown in figure 1 and 2, a complete stapedectomy stapes prosthetic for use in the middle ear of a person is generally indicated by reference numeral 10. The prosthetic 10 includes a spring-loaded tie-on 12 for tying onto the long process of an incus. The prosthetic 10 further includes an elongate connector 14 extending from the tie-on 12, which connector is configured to be length adjustable and which includes a shock absorber 16. The prosthetic 10 also includes a vibration transmission means 18 at the free end of the tie-on configured to interact with a foot plate.

The tie-on 12 is spring loaded wire a-loop and biased in the closed position. The tie-on 12 includes forceps engaging members, in the form of pins 20 configured such that a forceps can engage the clamp and allow a person to urge the tie-on into an open position to allow the tie-on to engage the long process during surgery.

The elongate connector 14 is also known as a piston. The piston 14 is in the form of a rod 22 inside a sleeve 24, with a spring captured inside the sleeve.

The rod 22 is provided with a thread at its free end, which is threadedly received in a threaded socket provided in the vibration transmission means 18. (pseudostapes foorplate)

The vibration transmission means 18, in the form of a footplate engagement means includes a cylindrical portion 26 at its free end followed by a pair of shoulders 28 followed by the rod 22.

Referring now to the rest of the drawings, different embodiments of stapes prosthetics for use in the middle ear, in accordance with the invention, is shown in Figures 4 and 5. The embodiments in Figures 4 and 5 are for partial stapedectomies and that shown in Figure 5 is for a complete stapedectomy.

In Figure 3, 30 shows a titanium bootshaped spring coupling arm to couple with the lower end of the cms 32. This prosthetic includes a jelly-like shield 34 around a new footplate 36 to act as an annular ligament for shock absorbsion of sound and atmospheric pressure. The footplate 36 manufactured from bone cement or a coupling cement to bind to the remaining oval window to prevent the footplate from entering too deep into the middle ear. In the embodiment shown in Figure 3, the prosthesis is generally oval in cross section and dimensioned replace the footplate, which is surgically removed, and also includes a shoulder 38 around its periphery to inhibit penetration into the inner ear to a certain predetermined depth.

The stapes connection means is in the form of a moisture activated clamp (titanium spring gelform mechanism) configured to clamp onto the cruras of the stapes (Figure 3) and a pair of moisture activated pre-stressed springs clamps configured to clamp, respectively, onto the anterior cms and posterior crus (Figure 4). The clamps are further configured to connect securely to the stapes with sufficient clamping surface and deformity yet to avoid loss of blood flow in the stapes. The prosthetic further includes a vibration transmission means for transmitting vibrations to the oval window of the middle ear. In the embodiments shown in Figure 4 and Figure 6, the vibration transmission means is in the form of a prosthesis with a spring 40 loaded pin 42 configured to protrude through a hole in the footplate which is surgically incised through the footplate membrane of the oval window The prosthesis includes a shoulder 38 around its periphery to inhibit penetration into the inner ear to a certain predetermined depth. The embodiment shown in figure 6 is for use for a complete stapedectomy and includes an attachment means 44 for attachment to the long process.

The malleus replacement prosthesis 50 shown in Figure 5, is shaped and configured to resemble a natural malleus and includes an attachment means 51 for attachment to a tympanic membrane 52 or part or remainder of a tympanic membrane, at one side and on the other side a connection means 54 for connecting to an incus or incus replacement prosthetic by means of a movable malleoincus joint to allow sound transmission. The tympanic membrane connection means 51 includes a silastic sheet for attachment to a tympanic membrane or to accept a replaced tympanic membrane. The connection means 56 for connecting the incus or incus replacement prosthetic 58 includes a u-channel shaped spring-loaded clamp, which can grip anywhere along the bony annulus of the malleus to compensate for different anatomies and sizes of the patient. The clamp includes jaws provided with teeth for a secure grip.

Similarly, the incus replacement prosthesis 58 is shaped and configured to resemble a natural incus and includes a malleus attachment means for attachment to a malleus or malleus replacement, at one side and on the other side a connection means 60 for connecting to a stapes or stapes replacement prosthetic 62 by means of a movable incostapedial joint to allow sound transmission. The connection means 56 for connecting to a malleus 50 is in the form of a ridge formation resembling a natural bony annulus to accept a clamp from a malleus prosthesis. Alternatively, the clamp may be located on the incus prosthesis and the ridge on the malleus prosthesis (not shown). The connection means for connecting to the stapes is in the form of a springloaded clamp for clamping onto the head of the stapes. The clamp includes jaws provided with teeth for a secure grip.

The body of the incus is elongate and the length of the body of the incus prosthesis is adjustable. The adjustability mechanism (not shown) is in the form of a piston ad sleeve configuration and optionally it is configured to absorb shock or excessive vibration from loud noises.

A malleus prosthetic, incus prosthetic and a stapes prosthetic can be combined for middle ear total ossicular replacement prosthesis. In the embodiment shown in figures 7 and 8, a complete stapedectomy stapes prosthetic for use in the middle ear of a person is generally indicated by reference numeral 10. The prosthetic 10 includes a spring-loaded tie-on 12 for tying onto the long process of an incus. The prosthetic 10 further includes an elongate connector 14 extending from the tie-on 12, which connector is configured to be length adjustable and which includes a shock absorber 16. The prosthetic 10 also includes a vibration transmission means 18 at the free end of the tie-on configured to interact with a foot plate. The tie-on 12 is c-shaped and spring loaded and biased in the closed position. The tie-on 12 includes forceps engaging members, in the form of pins 20 configured such that a forceps can engage the clamp and allow a person to urge the tie-on into an open position to allow the tie-on to engage the long process during surgery.

The elongate connector 14 is also known as a piston. The piston 14 is in the form of a rod 22 inside a sleeve 24, with a spring captured inside the sleeve. The rod 22 is provided with a thread at its free end, which is threadedly received in a threaded socket provided in the vibration transmission means 18.

It shall be understood that the examples are provided for illustrating the invention further and to assist a person skilled in the art with understanding the invention and are not meant to be construed as unduly limiting the reasonable scope of the invention.

Claims

1. A stapes prosthetic for use in the middle ear of a person, which prosthetic includes:

2. A stapes prosthetic as claimed in Claim 1 , wherein the stapes connection means is a spring-loaded tie-on for tying onto the long process of an incus.

3. A stapes prosthetic as claimed in Claim 1 , wherein the stapes connection means is a clamp.

4. A stapes prosthetic as claimed in Claim 3, which clamp is moist actuated.

5. A stapes prosthetic as claimed in Claim 3 or Claim 4, wherein a contact surface of the clamp is configured to spread a clamping force over a sufficiently large area of the stapes to allow blood flow in the stapes.

6. A stapes prosthetic as claimed in any one of claims 3 to 5, wherein the clamp is configured to clamp, respectively, onto the anterior crus and posterior crus.

7. A stapes prosthetic as claimed in Claim 3, wherein a single clamp is configured to be clamped to the incus and the distance between a prosthetic posterior and anterior crus of the stapes prosthetic is adjustable.

8. A stapes prosthetic as claimed in any one of the preceding claims 3 to 7, wherein the clamp is manufactured from a combination of titanium and bone cement.

9. A stapes prosthetic as claimed in any one of the previous claims, wherein the connecting body is configured to be length adjustable and includes a shock absorber.

10. A stapes prosthetic as claimed in any one of the previous claims, wherein the vibration transmission means at the free end of the connecting body is configured to interact with the oval window or part thereof.

11. A stapes prosthetic as claimed in any one of the preceding claims, wherein the vibration transmission means is in the form of a modeled prosthesis from a combination of spring, bone cement and titanium representing normal looking ossicles to protrude through a hole which is surgically incised through a footplate membrane of the oval window in contact with the gel tissue of the inner ear.

12. A stapes prosthetic as claimed in claim 11 , wherein vibration transmission means includes a shoulder around its periphery to inhibit penetration into the inner ear to a certain predetermined depth.

13. A stapes prosthetic as claimed in any one of the preceding claims, which includes a prosthetic posterior and anterior cms, each provided with braces for fitting onto anil btacing against the remaining part of the footplate, in use.

14. A malleus replacement prosthetic, which is shaped and configured to resemble a natural malleus, which prosthetic includes: an attachment means for attachment to a tympanic membrane or part or remainder of a tympanic membrane, at one side and on the other side a connection means of a movable malleoincus joint to allow sound transmission.

15. A malleus replacement prosthetic as claimed in claim 14, wherein the tympanic membrane connection means includes a silastic sheet for attachment to a tympanic membrane or to accept a replaced tympanic membrane.

16. A malleus replacement prosthetic as claimed in claims 14 or 15, wherein the connection means for connecting to an incus or incus replacement prosthesis includes a U-channel-shaped spring-loaded clamp, which can grip anywhere along the bony annulus of the incus to compensate for different anatomies and sizes of the patent.

17. A malleus replacement prosthetic as claimed in Claim 16, wherein the clamp includes jaws provided with teeth for a secure grip.

18. An incus replacement prosthetic, which is shaped and configured to resemble a natural incus, which prosthetic includes a malleus attachment means for attachment to a malleus or malleus replacement prosthetic, at one side and on the other side a connection means for connecting to a stapes or stapes replacement prosthetic by means ot a movable incostapedial joint to allow sound transmission.

19. An incus replacement prosthetic as claimed in claim 20, wherein a connection means for connecting to a malleus may be a ridge formation resembling a natural bony annulus to accept a clamp from a malleus prosthetic.

20. An incus replacement prosthesis as claimed in claims 18 or 19, wherein a clamp is located on the incus prosthesis and the ridge on the malleus prosthesis.

21. An incus replacement prosthesis as claimed in claim 20, wherein the clamp includes jaws provided with teeth for a secure grip.

22. An incus replacement prosthesis as claimed in claims 18 to 21 , wherein the connection means for connecting to the stapes is in the form of a spring- loaded clamp for clamping onto the head of the stapes.

23. An incus replacement prosthesis as claimed in claims 18 to 22, wherein a body of the incus is elongate and the length of the body of the incus prosthetic is adjustable.

24. An incus replacement prosthesis as claimed in claim 23, wherein the adjustability may be in the form of a piston and sleeve configuration and optionally it may be configured to absorb shock or excessive vibration from loud noises.

25. Use of the prosthetic in any one of the preceding claims to treat otosclerosis or any ailment which requires a stapedectomy procedure or osciculoplasty.