AU727911B2

AU727911B2 - arrangement for adjusting and fixing the relative position of two components of an active or passive hearing implant

Info

Publication number: AU727911B2
Application number: AU59433/99A
Authority: AU
Inventors: Rolf Lehner; Hans Leysieffer
Original assignee: Implex AG Hearing Technology
Current assignee: Sonova Holding AG
Priority date: 1997-09-03
Filing date: 1999-11-16
Publication date: 2001-01-04
Anticipated expiration: 2018-09-02
Also published as: AU5943399A

Description

IL

S F Ref: 425794D1

AUSTRALIA

PATENTS ACT 1990 COMPLETE SPECIFICATION FOR A STANDARD PATENT

ORIGINAL

Name and Address of Applicant: Actual Inventor(s): Address for Service: Invention Title: IMPLEX Aktiengesellschaft Hearing Technology Munchener Strasse 101 85737 Ismaning

GERMANY

Rolf Lehner and Hans Leysieffer Spruson Ferguson, Patent Attorneys Level 33 St Martins Tower, 31 Market Street Sydney, New South Wales, 2000, Australia Arrangement for Adjusting and Fixing the Relative Position of Two Components of an Active or Passive Hearing Implant The following statement is a full description of this invention, including the best method of performing it known to me/us:- 5845 -1- ARRANGEMENT FOR ADJUSTING AND FIXING THE RELATIVE POSITION OF TWO COMPONENTS OF AN ACTIVE OR PASSIVE HEARING IMPLANT Background of the Invention Field of the Invention The invention relates to an arrangement for adjusting the relative position of two components of an active or passive hearing implant and for fixing these elements in the relative position to which they have been adjusted.

Description ofRelated Art S. O Commonly owned, U.S. Patent No. 5,277,694 discloses an electromechanical transducer for implantable hearing aids for direct mechanical excitation of the middle or o inner ear, in which one wall of a hermetically sealed and biocompatible housing is made as an oscillatory membrane which, with a piezoelectric ceramic disk applied to the inside, represents an electromechanically active heteromorphic composite element, and whose o mechanical vibrations are transmitted via a mechanically stiff coupling rod fixedly secured S on the outside of the membrane and a mechanically stiff coupling element to the middle ear ossicle or directly to the inner ear.

In the known arrangement, the coupling element is made on the end to be joined to the coupling rod as a belt loop which is inserted into a bulge of the coupling rod, and which, in 2o the fixed state, loops the bulged part of the coupling rod on part of its periphery. Fixing takes place by pressing the belt loop closed or by application of a drop of adhesive. The mutual position of the coupling rod and coupling element in the axial direction of the coupling rod is strictly dictated by the bulge of the coupling rod, the bulge contributingto keeping the coupling element in the prescribed position with reference to the coupling rod. Likewise, the long term stability of the connection of the coupling rod and coupling elements may leave something to be desired.

Summary of the Invention The primary object of the present invention is to devise an arrangement which makes it possible to adjust the relative position of the two elements of an active or passive hearing 7 implant easily in-situ at the implantation site and to reliably fix the elements in the relative position to which they have been adjusted with long term stability.

-2- This object is achieved in accordance with the invention by an arrangement for adjusting the relative position of two elements of a hearing implant and for fixing the elements in an adjusted position thereof, wherein at least a part of a first one of the elements is belt loop-shaped in a fixing region thereof, wherein at least a part of a second one of the elements is straight rod-shaped in a fixing region thereof, and wherein, in a fixed state of said parts relative to each other, the loop-shaped part extends around the straight rod-shaped part of the second element over an angle of at least 3600 and is permanently attached on the rodshaped part without play by at least one of a force-fit and form-fit type connection The arrangement of the invention does not require a fixing aid according to the to coupling rod-bulge type of known approach. The rod-shaped part can rather be easily made straight, so that in the course of implantation, high flexibility for in-situ adjustment of the •relative position of the two elements is ensured, not only in the peripheral direction, but also S•in the axial direction of the rod-shaped part. The rod-shaped part is itself able to transfer forces in the axial direction which are orders of magnitude higher than the necessary I stimulation forces. The arrangement of the invention allows the loop-shaped part to be first loosely placed on the rod-shaped part during the operation, and then, the two parts to be moved into the proper relative position, followed by permanent attachment in-situ in the middle ear.

•Other preferred embodiments of the invention are also possible. In particular, one of the S• 2o two elements can be a coupling rod which is joined with an active oscillatory part of an implantable hearing aid transducer, while the other of the two elements is a coupling element which can be coupled to the ossicular chain or perilymph. The implant can also be made as a Stotal or partial replacement of the ossicular chain These and further objects, features and advantages of the present invention will become g- apparent from the following description when taken in connection with the accompanying drawings which, for purposes of illustration only, show several embodiments in accordance with the present invention.

Brief Description of the Drawings Fig. 1 is an enlarged schematic depiction of a hearing aid transducer with a coupling 2O rod; Fig. 2 shows, on an even larger scale, a perspective view of a coupling element joined to the coupling rod of the hearing aid transducer of Fig. 1 for coupling of the hearing aid transducer to the long incus process; Fig. 3 is a side view of the coupling element of Fig. 2; -3- Fig. 4 isa side view of a coupling element according to a modified embodiment; Figs. 5 is a side view of a coupling element with a bell-shaped coupling part; Fig. 6 shows a passive total prosthesis with a belt loop connection of the two prosthesis parts in schematic form; Fig. 7 shows another passive partial prosthesis with belt loop connection of the two prosthesis parts; Fig. 8 shows an embodiment of an arrangement for adjustment of the relative position of two elements of a hearing aid implant and for fixing these elements in the adjusted relative *..*position with the belt loop not yet tightened; and Figs. 9 and 10 are, respectively, a front view and a side view of the arrangement as shown in Fig. 8 after tightening of the belt loop.

Detailed Description of the Preferred Embodiments In Fig. 1, an implantable hearing aid transducer 10 is shown which can be made, for example, as a piezotransducer for vibratory stimulation of the ossicular chain. The hearing 5" aid transducer 10 has a biocompatible housing 11 which is hermetically sealed on all sides, and it can be equipped with an electromechanically active heteromorphic composite element of the type known from the initially mentioned U.S. Patent No.5,277,694.

A coupling rod 13 is mechanically securely joined to an active vibratory part 12 of the hearing aid converter 10, which is shown only schematically in Fig. 1. In the illustrated embodiment coupling rod 13 over its entire length essentially has the shape of a straight cylinder. If an electrical voltage is applied to the cable connection 14 of the hearing aid transducer 10, the coupling rod 13 is forced to execute vibratory oscillations in the axial direction of the coupling rod by means of the active vibratory part 12. Consequently, audio signals which are picked up by a microphone (not shown) are electrically converted, and after electronic amplification in an electronic module of the hearing aid, lead directly to mechanical displacements of coupling rod 13. These displacements correspond to acoustic information. Displacements of coupling rod 13 are relayed to the ossicular chain of the middle ear or to the stapes or the oval or round window, or also an artificial window, by mechanical coupling elements which can be fixedly secured on coupling rod 13. When the .ypreprocessing electronic system is designed accordingly, they cause an audiologic amplification effect.

Fig. 2 shows a coupling element 17 designed for connection of the coupling rod 13 to the long incus process 16. This coupling is suitable when the ossicular chain is intact. Here, in Fig. 2, the incudostapedial joint 18, stapes superstructure 19 and stapes footplate 20 are shown schematically. Coupling element 17 has a belt loop 69, C-shaped coupling part 23, and a middle part 24 which provides for a secure mutual connection of the belt loop 69 and coupling part 23. The belt loop 69 is shown in Figs. 2 to 7 only schematically but is 6 illustrated in further detail in Figs 8 to 10. The coupling element 17 is illustrated in Fig. 3 on a further enlarged scale. As shown there, the middle part 24 (Fig. 2) is formed of a bent wire piece, one arm 25 of which is longitudinally extended and is joined to the outside of belt loop 69, for example, soldered or welded. The free end of the other, short arm 26 of the middle part 24 fits into the eye 27 formed on the coupling part 23, where it is attached, for example, to by welding or soldering. In the mounted state, the C-shaped coupling part 23 surrounds the long incus process 16 (Fig. The C-shaped coupling part 23 can be wire-eroded especially S from pure titanium foil (purity 99.6 with a thickness on the order of 200 microns.

eeoo Fig. 4 shows a coupling element 29 according to a modified embodiment that is, likewise, especially suitable for coupling to the long incus process 16 (Fig. Here, the belt i( loop 69 is securely joined (for example, by a weld or solder connection) to a first cylindrical section 30 of the middle part 31. The cylindrical section 30 is adjoined by a conically tapering section 32 which passes into a second cylindrical section 33 that has a diameter which is less than that of section 30. Cylindrical section 33 is integrally joined to a belt loop 34 which can, for example, be placed around the long incus process 16.

ao Fig. 5 shows a further modified coupling element 36 which is suited primarily for coupling to the stapes head when the incus is missing. Coupling element 36 differs from the coupling element 17 of Figs. 2 and 3 essentially in that, in place of C-shaped coupling part o 23, a roughly bell-shaped coupling part 37 is attached to middle part 24. Coupling part 37 can correspond to the gold bell of conventional gold wire BELL prostheses (see Steinbach, E.; ,1 Pusalkar, Plester, D. (1990): Auditory ossicular replacement by gold prostheses.

Zentralblatt HNO-Heilkunde 139:133). Coupling part 37 can be placed on the stapes head and fixed there by pressing bell parts 38 together.

When the stapes superstructure is missing, the coupling of the hearing aid transducer to the perilymph can be produced by means of a coupling element 40 of the type illustrated in Figs. 8 through 10. Here, a rod-shaped coupling part 41 is provided in the manner of a stapespiston prosthesis which is securely joined via an intermediate member 67 to belt loop 69. For purposes of coupling to the perilymph, coupling rod 13 can be guided into the middle ear as an "artificial incus" through an opening of the facial recess (posterior tympanotom) and its distal end can be positioned over the oval niche. After perforation of footplate 20, for 3' example, by means of an erbium-YAG-laser, coupling part 41 is adjusted as in a stapedotomy and attached to coupling rod 13. The coupling part 41 is then inserted into the vestibulum via the footplate perforation.

The aforementioned coupling parts are similar to those of proven standard elements of middle ear prostheses and they offer the advantage that they can be mechanically closed with conventional standard OP instruments, for example, McGee instrument, otosurgical pincers, angulated hook, but, if necessary, can also be opened again.

It is common to the above described embodiments that the belt loop 69 can be loosely placed intraoperatively on the distal end of coupling rod 13, the coupling element pushed or turned axially and radially into the suitable position and the belt loop then attached securely in-situ onto the coupling rod 13.

Basically, external attaching on the operating table is also considered. Generally, Showever, this is prohibited because the coupling element, of course, can be attached only towards the end of implantation of the hearing aid on the ossicle since, otherwise, an increased risk of inner ear damage would have to be tolerated. Moreover, in external attaching, there is a danger of damaging the coupling element when the coupling rod is inserted. The coupling element could be detached again from the coupling rod then only with considerable cost.

For permanent and play-free attachment of the belt loop 69 on the coupling rod 13, it is important that the coupling rod 13 has a rough surface, at least in the fixing region. It is especially effective if the averaged peak-to-valley height of the surface roughness of coupling 2D rod 13 in the area of the connection to belt loop 69 is at least 10 microns.

Belt loop 69 is preferably made of gold, especially fine gold with a gold content of 99,99 which is preferably soft annealed. The soft annealing can be done, preferably, over roughly 10 minutes at a temperature on the order of 500 This soft annealed fine gold can have a Vickers hardness HV of, for example, For the hearing implant, as small a number as possible of different biometals should be used to preclude or minimize undesirable potential formation according to the electrochemical series. Therefore, preferably, not only belt loop 69, but the entire coupling element 17, 29 or 36 (with the exception of C-shaped coupling part 23) desirably should be made of fine gold. For this material, the biocompatibility and long-term stability have been 3 sufficiently verified, especially for the middle ear cavity. In addition., there is post-operative detachability of the ossicle coupling even after years in the body. This detachment of the connection is possible with moderate application of force using standard otosurgical instruments. Connection of coupling element 17, 19, 36 to the respective target ossicle or perilymph can thus take place based on proven standard elements of ordinary passive middle ear prosthesis.

-6- However, it goes without saying that, for the coupling element and especially also belt loop 69, other materials are likewise possible. For example, platinum, especially pure platinum, or silver, or alloys of gold, platinum or silver can be used.

Also, implantable titanium, especially pure titanium with a purity of>99.6 is suitable for coupling rod 13. In addition, platinum, niobium, or tantalum or alloys of titanium, platinum, niobium or tantalum are usable. Optionally, the coupling rod 13 can also be made of an implantable ceramic material, especially aluminum oxide.

In the material selection or construction, it should be noted that it is critical to apply the vibratory stimulus (action) of transducer 10 with as little loss as possible to the target ossicle to or the perilymph. In doing so, the total mass of the coupling element should preferably be less than the mass of the incus, which is, on average, 25 mg. Minimization of the weight of the coupling elements, at the same time, leads to reduction of the forces of inertia during acceleration by external effects such as impact, vibration, etc.

The connection explained in particular above, can also be provided for elements of a I6 passive hearing implant which is made as a total or partial replacement for the ossicular •chain. One embodiment for a total prosthesis is shown schematically in Fig. 6 at 58, while Fig. 7 shows an example of a partial prosthesis 59 via a similar schematic representation.

Total prosthesis 58 has a connection element 61 with an eardrum-side coupling part 62 for coupling of the prosthesis to the eardrum and a hollow cylinder part 63 attached securely S• ;o thereto. On its end away from coupling part 62, the cylinder part 63 passes into the belt loop 69. Furthermore, implant 58 includes a coupling rod 64 which plugs into the belt loop 69 and oooo optionally cylinder part 63. Coupling rod 64, at least in the fixing region, is provided with a rough surface in the manner explained above for coupling rod 13, and in the embodiment shown, it passes in one piece into the rod-shaped coupling part 41 which inserts, via an opening of stapes footplate 20, into the perilymph.

Coupling part 41 bears, on its end away from belt loop 69, a stop 65 which is, for example, ring-shaped for limiting the insertion depth of coupling part 41 The partial prosthesis as shown in Fig. 7 differs from the total prosthesis of Fig. 6 essentially only in that the end of coupling rod 64 away from coupling part 62 is joined to a bell-shaped coupling part 37 which can be placed on the stapes head, as described above.

In the implantation of prostheses 58 and 59, connection element 61 and coupling rod 64, analogously to the manner explained above, can be turned to opposite sides and can move in the axial direction, and they can be joined to one another permanently without play. In this way, the length of the total or partial prosthesis, and if necessary the mutual angular 36 alignment of coupling parts 62 and 41 or 37, can be easily and quickly adjusted -7intraoperatively according to the individual patient.

Figs. 8, 9, and 10 show an embodiment of an arrangement for adjusting the relative position of two elements of a hearing implant and for fixing these elements in the adjusted relative position. Coupling element 67 has rod-shaped coupling part 41 and a belt loop 69 C which is joined thereto via intermediate member 68 and which can be tightened around coupling rod 13. In the fixed state illustrated in Figs. 9 and 10, belt loop 69 loops fully around coupling rod 13, over an angle of at least 3600, to provide a force-fit and/or formfit fixing of the belt loop 69 relative to coupling rod 13 in the adjusted position. A form-fit can be provided especially by the fact that not only coupling rod 13, but also belt loop 69, is .o roughened on its side facing the coupling rod, so that when belt loop 69 is tightened, mutual S• microdenticulation occurs between the belt loop and coupling rod. Optionally, additional security by material-fit can be provided, for example, by applying a small amount of surgical bone cement 70 in the manner shown schematically in Fig. It goes without saying that, in the embodiments shown in Figs. 8 to 10, in place of a "rod-shaped coupling part 41, also a C-shaped coupling part 23 or belt loop 34 or bell-shaped coupling part 37 can be provided. Correspondingly, in the partial prosthesis as shown in Fig.

7; a bell-shaped coupling part 37 can be replaced by a C-shaped coupling part 23 or belt loop 34. Also, with respect to other features, the described arrangements can be easily varied.

o:ooo While various embodiments in accordance with the present invention have been shown oooeo X and described, it is understood that the invention is not limited thereto, and is susceptible to numerous changes and modifications as known to those skilled in the art. Therefore, this o •o invention is not limited to the details shown and described herein, and includes all such Schanges and modifications as are encompassed by the scope of the appended claims.

Claims

2. Arrangement as claimed in claim 1, wherein in the fixed state of the loop-shaped part, additional securement of the loop-shaped part on the rod-shaped part is provided with a surgical bone cement or glue. gong
3. Arrangement as claimed in claim 1, wherein the loop-shaped part and the rod-shaped part are roughened on facing surfaces thereof, at least in the fixing region. S 4. Arrangement as claimed in claim 1, wherein the loop-shaped part is axially movable along the rod-shaped part prior to fixing thereof.
5. Arrangement as claimed in claim 4, wherein the loop-shaped part is rotatable relative to the rod-shaped part prior to fixing thereof S 6. Arrangement as claimed in claim 1, wherein the rod-shaped part of the other element is straight, at least in the fixing region.
7. Arrangement as claimed in claim 1, wherein the first one of the two elements is a coupling rod which is joined with an active oscillatory part of an implantable hearing aid transducer and the second of the two elements is a coupling element which is connectable to one ossicle of the ossicular chain and perilymph.
8. Arrangement as claimed in claim 7, wherein the coupling element has a crimp sleeve, a coupling part for a respective coupling site in the middle ear and a middle part which connects the crimp sleeve and the coupling part together.
9. Arrangement as claimed in claim 8, wherein the middle part is deformable. Arrangement as claimed in claim 7, wherein the coupling element has a C-shaped coupling part which is positionable around a part of the ossicular chain. -9- S1. Arrangement as claimed in claim 7, wherein the coupling element has a belt loop which is positionable around a part of the ossicular chain.
12. Arrangement as claimed in claim 7, wherein the coupling element has a roughly bell- shaped coupling part which is positionable around a part of the ossicular chain.
13. Arrangement as claimed in claim 7, wherein the coupling element has a rod-shaped coupling part which is insertable into the vestibulum via a footplate perforation.
14. Arrangement as claimed in claim 1, wherein the implant is at least a partial replacement for the ossicular chain.
15. Arrangement as claimed in claim 1, wherein the first one of the elements, at least in the fixing region, is made of a material selected from the group consisting of gold, platinum, silver, or alloys thereof.
16. Arrangement as claimed in claim 15, wherein the second one of the elements, at least in the fixing region, is made of a material selected from the group consisting of titanium, platinum, niobium, or tantalum or alloys thereof, implantable high quality steel, or a ceramic material. S17. An arrangement for adjusting the relative position of two elements of a hearing implant and for fixing the elements in an adjusted position thereof, the arrangement substantially as hereinbefore described with reference to Fig. 1 to 3, Fig. 4 or Fig 5 of the accompanying drawings. S Dated 16 November, 1999 IMPLEX Aktiengesellschaft Hearing Technology Patent Attorneys for the Applicant/Nominated Person SPRUSON FERGUSON