WO2014190953A2

WO2014190953A2 - Prosthetic system for replacing the ossicles of the middle ear

Info

Publication number: WO2014190953A2
Application number: PCT/CU2014/000002
Authority: WO
Inventors: Ramòn GONZALEZ SANTOS
Original assignee: Centro De Neurociencias De Cuba (Neuronic)
Priority date: 2013-05-28
Filing date: 2014-05-27
Publication date: 2014-12-04
Also published as: CU20130074A7

Abstract

The invention concerns a prosthetic system for replacing the ossicles of the middle ear, designed both for partial (anvil or stirrup) and total (both components) replacement of the chain of ossicles of the middle ear, in order to restore hearing in patients suffering from a loss of hearing for this reason. The system is produced preferably from biocompatible photopolymers of which the bioactivity is increased by the addition of micro- and nanoparticles of calcium carbonates, phosphates, hydroxide, titanium oxide, hydroxyapatite and carbonate apatite, or a mixture thereof. It is thus possible to monitor the patients post-operatively, using any of the imaging technologies since the density of the material from which the prosthetic system is produced is very similar to that of bone. In all cases, complete stability of the implant can be attained by securing it by way of a fastener system, complemented if necessary with a cementing substance which is biocompatible with the bone.

Description

DESCRIPTION

PROTESIS SYSTEM FOR THE REPLACEMENT OF MID-EAR BONES

The present invention is directed to the manufacture of a simple and functional system of implantable prostheses that allows partial or total replacement of the ossicles chain of the middle ear when they are lost or damaged. With this system, the objective is to recover the hearing loss lost in patients suffering from this disability due to this cause.

It is also the objective of the present invention to manufacture said prosthetic system in biocompatible acrylic photopolymers loaded with calcium hydroxycarbonates-phosphates to increase its bioactivity.

The middle ear contains a chain of three bones that are attached to each other and extend from the tympanic membrane to the ova window! of the inner ear These bones are commonly known as the hammer, anvil and stirrup. They are also called ossicles chain! middle ear or auditory ossicles (Meakins, J. L. Innovation ¡n surgery: The rules of evidence. The American Journal of Surgery, 2002; 183: 399-405. Frost, CEB Physicians and medical innovation. Social Science & Medicine, 1985; 21: 1 193-1 198. Hyvárinen, L et.al. Disorders of the eye, ear, nose and throat.In: Rosenstock, L. Ed. Textbook of Clinicai Occupational and Environmental Medicine, 2nd Edition, Elsevier Saunders, Philadelphia, 2005; 419-452. Chen, H., Okumura, T., Emura, S. and Shoumura, S. Scanning electron microscopic study of the human auditory ossicles. Annals of Anatomy, 2008; 190: 53-58). This ossicular chain begins with the hammer, which is coupled with the eardrum and transfers or transmits the vibrations of the tympanic membrane through the anvil and the stirrup. These bones are connected to each other through joints that allow you to transfer the vibratory movement from one bone to the other. The stirrup is the last of this chain and transfers the vibrations to the cochlea of the inner ear that is located in the vestibule. When the movement of these bones is impeded for some pathological or traumatic reason due to the deterioration of one of the bones or their joints, hearing loss occurs. This chain can be reconstructed and the hearing restored using artificial elements that are known as replacement prostheses for the middle ear ossicles (ORP) (Nakajima, HH, et. al .. Experimental ossicular fixations and the middle ear's response to sound: Evidence for a flexible ossicular chain. Hearing Research, 2005; 204: 60-77.). Reconstruction surgery involves the reconstitution of the sound conduction bridge by removing the dysfunctional elements of the chain and replacing them with ossicle prostheses (ORP) (Emmett, JR Ossicular chain reconstruction. Operative Techniques in Otolaryngology-Head and Neck Surgery , 1995; 6: 22-26.). Thus, "Ossiculoplasty" is the surgical intervention that is performed to implant the prostheses in the middle ear cavity through a surgical procedure where an incision is made through the external auditory canal to place the prosthesis. The replacement of the anvil and the stirrup of the chain is called total prosthesis (TORP), and when only the anvil or stirrup is replaced then it is called partial (PORP) (Berenholz, L. and Lippy, WH Total ossiculoplasty with footplate removal. Otolaryngology-Head and Neck Surgery, 2004; 130: 120-124. Wiet, RJ, Wiet, RM Experience-driven ossiculoplasty. Operative Techniques in Otolaryngology- Head and Neck Surgery, 2010; 21: 21 1-2168,). Both types of prostheses should be in contact with the remnant of the tympanic membrane or the reconstructed tympanic membrane if necessary. Materials for ossicle replacement prostheses must have low mechanical inertia, low mechanical damping, as well as be durable and biocompatible (Hales, NW, Shakir, FA, and Saunders, JE Titanium middle ear prostheses in staged ossiculoplasty: does mass really matter? American Journal of Otolaryngology, 2007; 28: 164-167.). In current surgical practice, the prostheses are attached to the ossicular chain using wires, springs and surgical cements. Since the size of the components of the ossicular chain may be different for different individuals, manufacturers generally manufacture prostheses of various sizes so that they can accommodate a wide range of patients. Some manufacturers also make the components in such a way that the dimensions can be varied and thus can be adjusted to each patient.

Ear bone reconstruction surgery was introduced in 1956 by Shea, when he used stirrup replacement as a treatment for otosclerosis (Shea JJ Jr. A personal history of stapedectomy. Am J Otol 1998; 19: S2-12. ). Since then, many improvements have been made, including the small incision stapedoctomy technique in the 1970s (House HP. The evolution of otosclerosis surgery. Otolaryngol Clin North Am 1993; 26: 323-33). Currently, there are a large number of prosthetic models of all types (Fritsch MH, Naumann IC. Phylogeny of the stapes prosthesis. Otol Neurotol 2008; 29: 407-15) where the most obvious differences are related to the fixation mechanisms , the materials used and the diameter of the piston. The most commonly used piston diameters are 0.4 and 0.6 mm, with 0.3, 0.5 and 0.8 mm long, the latter being used less frequently. Under physiological conditions, the area for sound transmission (stirrup base) is approximately 3.2 mm ² (Huttenbrink KB. Biomechanics of stapesplasty: a review. Otol Neurotol 2003; 24: 548-57; discussion 57-9) . The choice of the diameter of the prosthesis may be limited by the individual anatomy of each patient, such as an outstanding facial nerve or obliteration of the oval window, which requires smaller diameters of the prosthesis for implantation to be possible. In addition, a larger prosthesis requires greater opening of the inner ear and may increase the risk of trauma or fracture of the base of the stirrup. The mass of the prosthesis can also cause a slight shift in the resonance frequency. Thus, for example, a smaller mass of the prosthesis translates into better transmission of higher frequencies while heavier prostheses produce better results at lower frequencies (Huttenbrink KB. Biomechanics of stapesplasty: a review. Otol Neurotol 2003; 24: 548-57; discussion 57-9). The function of the diameter of the prosthesis is also a controversial aspect, since it is suggested that any variation in the diameter is compensated by the fact that the volume of the perilymphatic fluid in the cochlea remains the same. Both clinically and experimentally (Fucci MJ, Lippy WH, Schuring AG, et al. Prosthesis size in stapedectomy. Otolaryngol Head Neck Surg 1998; 1 18: 1-5. Grolman W, Tange RA, from Bruijn AJ, et al. A retrospective study of the hearing results obtained after stapedotomy by the implantation of two Teflon pistons with a different diameter. Eur Arch Otorhinolaryngol 1997; 254: 422Y4. Ha ^' usler R. Fortschritte in der Stapeschirurgie. Laryngo-Rhino-Otol 2000; 79: 95-139 Mangham CA Jr. Titanium CliP piston versus platinum-ribbon Teflon piston: piston and fenestra size affect air-bone gap Otol Neurotol 2008; 29: 8-12 Marche MR, Cianfrone F, Passali GC, et al. Hearing results after stapedotomy: role of the prosthesis diameter Audiol Neurootol 2007; 12: 221-5 Sennaroglu L, Unal OF, Sennaroglu G, et al. Effect of Teflon piston diameter on hearing result after stapedotomy Otolaryngol Head Neck Surg 2001; 124: 279-81 Shabana YK, Ghonim MR, Pedersen CB Stapedotomy: does prosthesis diameter affect outcome? Clin Otolaryngol Allied Sci 1999; 24: 91-4. Teig E, Lindeman HH. Stapedotomy piston diameterVis bigger better? Otorhinolaryngol Nova 1999; 9: 253-7.) (Huttenbrink KB. Biomechanics of stapesplasty: a review. Otol Neurotol 2003; 24: 548-57; discussion 57-9., Rosowski JJ, Merchant SN. Mechanical and acoustic analysis of middle ear reconstruction, Am J Otol 1995; 16: 486-97., Bohnke F, Arnold W. Finite element model of the stapes-inner ear ¡nterface. Adv Otorhinolaryngol 2007; 65: 150-4) studies have tried to respond to the question about the optimal diameter for a prosthesis, but the results have not been definitive. Some conclusions are contradictory, and the materials, surgical techniques and analyzes used have been heterogeneous. An important issue is the difficulty of having large population groups to deal with, enough to achieve the necessary significance or weight of the results.

It can be said that until today there is no prosthetic system that can meet the demands and requirements of different uses (partial and total). From the accumulated experience it is known that the main elements to be taken into account to obtain optimal results in the development of these devices are: the type of material and the shape and dimensions of the prosthesis (Román D. Laske, Christof Ro ^"' or ^" sli , et. al .. The Influence of Prosthesis Diameter in Stapes Surgery: A Meta-Analysis and Systematic Review of the Literature, Otology & Neurotology 2011; 32: 520-528. Yuri M. Gelfand, and CY Joseph Chang, Ossicular Chain Reconstruction Using Titanium versus Hydroxyapatite Implants Otolaryngology - Head and Neck Surgery published online 18 February 201 1. DOI: 10 _, .1 177/019459981 1399738. http://oto.sagepub.com/content/early/201 / 02/14 / 019459981 1399738).

There are several types of prostheses of the middle ear, with different models or designs and made of diverse materials such as hydroxyapatite ceramics, metals such as titanium and others that have a series of disadvantages or defects, such as:

In US 5,061,280 of October 29, 1991, a complicated device composed of several parts made of different materials is described, which rests on the tympanic membrane on one side and the other side is directed to the base of the stirrup or to the entrance of the inner ear. This type of prosthesis has the disadvantage that besides being able to be used only in the In case of complete replacement of the ossicle chain (total prosthesis), its fixation is difficult and it tends to migrate from the implantation site.

Another type of total prosthesis made of gold and titanium (US 5,514, 177 of May 7, 1996) has the disadvantage that the metals are not bioactive so that the natural fixation of the implant to the tissue environment does not occur with the risk of its possible migration and with the consequent difficulties for the transmission of sound and can even lead to implant failure, in addition to its high cost due to the type of material used.

Another implant made of a superelastic metal alloy (US 6,203,571 B1 of May 20, 2001) has the same disadvantages mentioned above.

A series of implants whose designs are intended to solve the problem of fixation are reported in the documents, EP 1498088 A2 of January 19, 2005, US 7,204,850 B2 of April 17, 2007, US 2007/0021833 A1 of June 25, 2007 , US 2008/0208337 A1 of August 28, 2008 and EP 2072026 of June 24, 2009. In all cases the designs contemplate systems of clips at anchor points, which improves stability, however, also in all The cases are manufactured with metallic materials such as titanium, titanium and ninitol alloys, which brings a series of disadvantages associated with the material such as lack of bioactivity, high density, high thermal and electrical conductivity, complexity and high manufacturing costs among other.

An improved version of this type of device is described in WO 2011/080363 A1 of July 7, 2011 as it takes into account the anatomical and physiological characteristics of the middle ear and the disadvantages of its predecessors in terms of material deficiencies construction, design deficiencies and others. However, this prosthesis still has some limitations, such as:

- applies only in the case of a total replacement of the ossicles chain, - It is stated that although the prosthesis can be constructed of plastic material such as Teflon, it will preferably be made of titanium, which preserves the limitations or disadvantages indicated above when metals are used to construct this type. of device.

The prosthesis system developed in the present invention has the following advantages:

1- It is designed for both partial replacement (anvil or stirrup) and total (both components) of the ossicles chain of the middle ear.

2- It incorporates the favorable elements in terms of adaptability to the anatomical and physiological structure of the middle ear and resolves the deficiencies, defects or disadvantages of its predecessors.

3- It is preferably manufactured in biocompatible photopolymers whose bioactivity is considerably increased by the addition of micro and nanoparticles of phosphates, hydroxide, calcium carbonates, hydroxyapatite and carbonate-apatite, titanium oxide or mixture thereof, whereby the Postoperative follow-up of patients using any of the imaging techniques, since the density of the manufacturing material is very similar to that of bone.

4 - It allows in all cases to achieve the complete stability of the implant by means of its fixation through a mechanism of a supplementary clip if necessary with a cementing substance biocompatible with the bone.

5 - The system can be manufactured in 3D printers from a solid three-dimensional image of the design made by CAD (Computer Aided Design), which allows great accuracy and precision in the reproduction of the characteristics of the system in addition to high productivity and Low implant costs.

The characteristics of the prosthesis system proposed in the present invention are set forth below.

The system consists of 3 components or variants, one for the replacement of the stirrup, another for the replacement of the anvil and another for the replacement of both, the anvil and the stirrup. The system component intended for the case in which only the stirrup replacement is necessary (Fig. 1), is formed by a kind of truncated cone (1) that is extended by the part of smaller diameter in the form of "U" ( 2) that it has the most closed entrance so that it can be anchored to! free end of the anvil after removing the stirrup (Fig. 1A). The "U" has the side part (3) wider than the front part (4) and on the inside it has a rough or wavy surface (5) that facilitates the strong grip on the free end of the anvil (6). The other distal end and of greater diameter rests on the remaining base of the stirrup or directly on the oval window (7) (Fig. 1 B). Anchoring at both ends can be strengthened if necessary by supplementing with calcium phosphate-based cements. In this way the chain of ossicles is reconnected.

In the case that only the anvil replacement is necessary, the hammer can be connected to the stirrup through the device shown in Fig. 2. It is formed by a rod of variable and curved diameter (1) in such a way that can save the known eccentricity of the oval window with respect to the hammer handle (Fig. 2A). In the same way, the end of smaller diameter extends in the form of "U" (2) that has the most closed entrance so that a "clip" effect can be achieved to anchor to the hammer handle (7) (Fig. 2B). Said "U" has the side part (3) wider than the front part (4) and on the inside it has a rough or wavy surface transversely (5) that facilitates the strong grip. The distal or larger diameter part ends with a cavity in its base (6) in which the stirrup head (8) enters and connects. If the replacement of both bones (stirrup and anvil) is necessary, the distal or larger diameter end ends with a flat base (9) that extends to the oval window and rests on the remaining base or plate of the stirrup or directly above the lobby (1 Q).

Claims

1- A prosthetic system for the replacement of the ossicles of the middle ear, characterized in that it is formed by three parts intended to replace the stirrup, or the anvil or both ossicles. 2- A prosthetic system for the replacement of the ossicles of the middle ear, according to claim No. 1, characterized in that it contemplates a device intended for the replacement of the stirrup consisting of a truncated cone that extends by way of the smaller diameter of "U" with rough inner surface that provides the adjustment or grip necessary to be fixed to the free end of the anvil. At the other end of greater diameter it ends on a flat surface that sits on the base of the stirrup or directly in the vestibule of the inner ear.

3- A prosthetic system for the replacement of the ossicles of the middle ear, according to claim No. 1 characterized in that it contemplates a device intended for the replacement of the anvil consisting of an arcuate rod that has a termination at the end of smaller diameter "U" with a rough inner surface by which it is fixed to the hammer handle and the other end of greater diameter ends in a longitudinal hole to the axis of said rod where the stirrup head is inserted and fixed. 4- A prosthetic system for the replacement of the ossicles of the middle ear, according to claims 1 and 3 characterized in that the device itself for the replacement of the anvil can end at the end of greater diameter on a flat surface and extend to the vestibule of the oval window to replace the complete chain of ossicles of the middle ear.

5- A prosthetic system for the replacement of the ossicles of the middle ear, according to claim No. 1 characterized in that without discarding other biocompatible solid materials such as titanium and its alloys, ceramic biomaterials and others, they will preferably be manufactured with acid-derived photopolymers acrylic, mixtures of acrylates or mixtures of photopolymerizable biocompatible polymers loaded with phosphates, hydroxide, calcium carbonates, hydroxyapatite and carbonate-apatite, titanium oxide or mixture thereof.

6- A prosthetic system for the replacement of the ossicles of the middle ear, according to claims 1 and 5, characterized in that without excluding other manufacturing methods, 3D printing from computer-designed images (CAD) will preferably be used.

7- A prosthetic system for the replacement of the ossicles of the middle ear, according to claims 1 and 5, characterized in that the fixation at each end of the prostheses can be ensured by the additional use of cementing bioactive substances at the contact border between living tissue and the implant.